COSTILLA ENERGY INC
S-1/A, 1996-08-30
CRUDE PETROLEUM & NATURAL GAS
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<PAGE>
   
    AS FILED WITH THE SECURITIES AND EXCHANGE COMMISSION ON AUGUST 30, 1996
    
 
   
                                                      REGISTRATION NO. 333-08909
    
- --------------------------------------------------------------------------------
- --------------------------------------------------------------------------------
 
                       SECURITIES AND EXCHANGE COMMISSION
                             WASHINGTON, D.C. 20549
 
                            ------------------------
 
   
                                AMENDMENT NO. 1
                                       TO
    
                                    FORM S-1
 
                             REGISTRATION STATEMENT
                                     UNDER
                           THE SECURITIES ACT OF 1933
                            ------------------------
 
                             COSTILLA ENERGY, INC.
             (Exact name of Registrant as specified in its charter)
 
<TABLE>
<S>                              <C>                             <C>
            DELAWARE                           1311                     75-2658940
 (State or other jurisdiction of   (Primary Standard Industrial      (I.R.S. Employer
 incorporation or organization)    Classification Code Number)     Identification No.)
</TABLE>
 
                            ------------------------
 
                         400 WEST ILLINOIS, SUITE 1000
                              MIDLAND, TEXAS 79701
                                 (915) 683-3092
              (Address, including zip code, and telephone number,
       including area code, of Registrant's principal executive offices)
 
                          MICHAEL J. GRELLA, PRESIDENT
                             COSTILLA ENERGY, INC.
                         400 WEST ILLINOIS, SUITE 1000
                              MIDLAND, TEXAS 79701
                                 (915) 683-3092
           (Name, address, including zip code, and telephone number,
                   including area code, of agent for service)
 
                            ------------------------
 
                                   COPIES TO:
 
<TABLE>
<S>                                            <C>
             Richard T. McMillan                              R. Joel Swanson
      Cotton, Bledsoe, Tighe & Dawson,                     Baker & Botts, L.L.P.
         a Professional Corporation                            910 Louisiana
              500 West Illinois                            Houston, Texas 77002
                  Suite 300
            Midland, Texas 79701
</TABLE>
 
                            ------------------------
 
    APPROXIMATE  DATE OF COMMENCEMENT OF PROPOSED SALE TO THE PUBLIC: As soon as
practicable after this Registration Statement becomes effective.
 
    If any of the securities being registered on this Form are to be offered  on
a  delayed or continuous basis pursuant to  Rule 415 under the Securities Act of
1933, check the following box: / /
 
    If this Form  is filed  to register  additional securities  for an  offering
pursuant to Rule 462(b) under the Securities Act, please check the following box
and  list  the  Securities  Act registration  statement  number  of  the earlier
effective registration statement for the same offering.  / /
 
    If this Form  is a post-effective  amendment filed pursuant  to Rule  462(c)
under  the Securities Act, check  the following box and  list the Securities Act
registration statement number  of the earlier  effective registration  statement
for the same offering.  / /
 
    If  delivery of the Prospectus is expected  to be made pursuant to Rule 434,
please check the following box.  / /
 
                            ------------------------
 
    THE REGISTRANT HEREBY  AMENDS THIS  REGISTRATION STATEMENT ON  SUCH DATE  OR
DATES AS MAY BE NECESSARY TO DELAY ITS EFFECTIVE DATE UNTIL THE REGISTRANT SHALL
FILE  A  FURTHER  AMENDMENT  WHICH SPECIFICALLY  STATES  THAT  THIS REGISTRATION
STATEMENT SHALL THEREAFTER BECOME EFFECTIVE  IN ACCORDANCE WITH SECTION 8(A)  OF
THE  SECURITIES ACT  OF 1933  OR UNTIL  THE REGISTRATION  STATEMENT SHALL BECOME
EFFECTIVE ON SUCH DATE AS THE COMMISSION, ACTING PURSUANT TO SAID SECTION  8(A),
MAY DETERMINE.
 
- --------------------------------------------------------------------------------
- --------------------------------------------------------------------------------
<PAGE>
INFORMATION   CONTAINED  HEREIN  IS  SUBJECT   TO  COMPLETION  OR  AMENDMENT.  A
REGISTRATION STATEMENT  RELATING TO  THESE SECURITIES  HAS BEEN  FILED WITH  THE
SECURITIES  AND EXCHANGE  COMMISSION. THESE SECURITIES  MAY NOT BE  SOLD NOR MAY
OFFERS TO BUY BE ACCEPTED PRIOR  TO THE TIME THE REGISTRATION STATEMENT  BECOMES
EFFECTIVE.  THIS  PROSPECTUS  SHALL  NOT  CONSTITUTE AN  OFFER  TO  SELL  OR THE
SOLICITATION OF AN OFFER TO BUY NOR SHALL THERE BE ANY SALE OF THESE  SECURITIES
IN  ANY STATE IN WHICH SUCH OFFER,  SOLICITATION OR SALE WOULD BE UNLAWFUL PRIOR
TO REGISTRATION OR QUALIFICATION UNDER THE SECURITIES LAWS OF ANY SUCH STATE.
<PAGE>
   
                  SUBJECT TO COMPLETION, DATED AUGUST 30, 1996
    
 
PRELIMINARY PROSPECTUS
                                  $100,000,000
 
   
                             COSTILLA ENERGY, INC.
    
 
                       % SENIOR SUBORDINATED NOTES DUE 2006
                               -----------------
 
    The   % Senior Subordinated Notes  due 2006 (the "Notes") are being  offered
(the  "Notes  Offering")  by  Costilla  Energy,  Inc.,  a  Delaware  corporation
("Costilla" or the "Company"). The net proceeds of the Notes Offering,  together
with  the net proceeds of the other  financing described herein, will be used by
the Company  to  refinance  existing  indebtedness,  to  pay  certain  costs  in
connection with the Corporate Reorganization (as defined herein) and for general
corporate purposes.
 
   
    The Notes mature on          , 2006, unless previously redeemed. Interest on
the  Notes is  payable semiannually on              and             , commencing
         , 1997. The Notes will be redeemable  at the option of the Company,  in
whole  or in part, on  or after            , 2001,  at the redemption prices set
forth herein, plus accrued and unpaid interest, if any, to the redemption  date.
Notwithstanding  the foregoing,  at any  time on or  before              , 1999,
Costilla may redeem up to 30% of the original aggregate principal amount of  the
Notes  with the  net proceeds  of an  Equity Offering  (as defined  herein) at a
redemption price equal to   % of the principal amount thereof, plus accrued  and
unpaid  interest  thereon, if  any, to  the  redemption date.  Upon a  Change of
Control (as defined herein), the  Company will be required  to make an offer  to
repurchase  all  outstanding Notes  at 101%  of  the aggregate  principal amount
thereof plus accrued and unpaid interest, if any, to the date of repurchase. See
"Description of Notes."
    
 
   
    Concurrently with  the Notes  Offering, the  Company is  offering  4,000,000
shares (4,600,000 shares if the underwriters' over-allotment option is exercised
in  full) of its Common Stock (the "Common Stock Offering" and together with the
Notes Offering, the  "Offerings") pursuant to  an underwritten public  offering.
The  Notes Offering and  the Common Stock  Offering are each  conditioned on the
consummation of the other.
    
 
   
    The Notes will be general unsecured obligations of the Company, subordinated
in right of payment to all  existing and future Senior Indebtedness (as  defined
herein)  of the Company, which will include borrowings under the Credit Facility
(as defined herein).  As of June  30, 1996, on  a pro forma  basis after  giving
effect to the Corporate Reorganization, the Offerings and the application of the
proceeds therefrom, as described under "Use of Proceeds", the Company would have
had  $0.4  million of  Senior Indebtedness.  No indebtedness  of the  Company is
expressly subordinated to the  Notes. Initially, both the  Notes and the  Credit
Facility  will  be  effectively  subordinated to  liabilities  of  the Company's
subsidiaries. On  a pro  forma basis,  the total  liabilities of  the  Company's
subsidiaries  were $6.5 million  at June 30,  1996, all of  which were operating
liabilities. See "Risk Factors," "Capitalization" and "Description of Notes."
    
 
   
    The Notes will be represented by a Global Certificate registered in the name
of the nominee of The Depository Trust Company, which will act as the Depositary
(the "Depositary"). Beneficial interests in the Global Certificate will be shown
on, and transfers thereof will be  effected only through, records maintained  by
the  Depositary  and  its participants.  Except  as described  herein,  Notes in
definitive form  will  not be  issued.  See "Description  of  Notes--Book-Entry,
Delivery and Form."
    
 
   
    The  Company does not  intend to list  the Notes on  any national securities
exchange. See "Risk Factors--  Absence of Public  Market." Application has  been
made  to list  the Common  Stock on  The Nasdaq  Stock Market's  National Market
("Nasdaq National Market") under the symbol "COSE".
    
 
   
    SEE "RISK FACTORS"  BEGINNING ON PAGE  10 FOR A  DISCUSSION OF FACTORS  THAT
SHOULD BE CONSIDERED IN EVALUATING AN INVESTMENT IN THE NOTES.
    
                            ------------------------
THESE SECURITIES HAVE NOT BEEN APPROVED OR DISAPPROVED BY THE SECURITIES AND
    EXCHANGE  COMMISSION OR ANY  STATE SECURITIES COMMISSION  NOR HAS THE
       SECURITIES  AND  EXCHANGE  COMMISSION  OR  ANY  STATE   SECURITIES
       COMMISSION   PASSED  UPON  THE  ACCURACY  OR  ADEQUACY  OF  THE
          PROSPECTUS. ANY    REPRESENTATION  TO THE  CONTRARY IS  A
                               CRIMINAL OFFENSE.
<TABLE>
<S>                                                  <C>               <C>               <C>
- ---------------------------------------------------------------------------------------------------------
 
<CAPTION>
                                                         Price to        Underwriting      Proceeds to
                                                        Public (1)      Discounts (2)     Company (1)(3)
<S>                                                  <C>               <C>               <C>
- ---------------------------------------------------------------------------------------------------------
Per Note...........................................         %                 %                 %
Total..............................................    $100,000,000           $                 $
- ---------------------------------------------------------------------------------------------------------
</TABLE>
 
(1) Plus accrued interest, if any, from         , 1996.
   
(2)  The Company  has agreed to  indemnify the Underwriters  (as defined herein)
    against certain liabilities, including liabilities under the Securities  Act
    of 1933, as amended. See "Underwriting."
    
   
(3) Before deducting expenses payable by the Company, estimated at $600,000.
    
 
    The  Notes are  being offered,  subject to  prior sale,  by the Underwriters
when, as and  if issued  to and  accepted by  the Underwriters,  and subject  to
various prior conditions. The Underwriters reserve the right to withdraw, cancel
or  modify such offer and to  reject orders in whole or  in part. It is expected
that delivery of the Global Certificate will be made on or about               ,
1996  in  book-entry  form through  the  facilities of  the  Depositary, against
payment therefor.
 
NATIONSBANC CAPITAL MARKETS, INC.  PRUDENTIAL SECURITIES INCORPORATED
 
   
                The date of this Prospectus is          , 1996.
    
<PAGE>
   
                            PRIMARY OPERATING AREAS
    
 
   
              [A GEOGRAPHICAL MAP INDICATING WHERE THE COMPANY HAS
                      OIL AND GAS PROPERTIES AND OFFICES]
    
 
   
    IN CONNECTION WITH THIS NOTES  OFFERING, THE UNDERWRITERS MAY OVER-ALLOT  OR
EFFECT TRANSACTIONS WHICH STABILIZE OR MAINTAIN THE MARKET PRICE OF THE NOTES AT
A  LEVEL  ABOVE THAT  WHICH MIGHT  OTHERWISE  PREVAIL IN  THE OPEN  MARKET. SUCH
TRANSACTIONS  MAY  BE   EFFECTED  IN   THE  OPEN  MARKET   OR  OTHERWISE.   SUCH
STABILIZATION, IF COMMENCED, MAY BE DISCONTINUED AT ANY TIME.
    
<PAGE>
                               PROSPECTUS SUMMARY
 
   
    THE  FOLLOWING  SUMMARY  IS  QUALIFIED  IN  ITS  ENTIRETY  BY  THE  DETAILED
INFORMATION, FINANCIAL STATEMENTS  AND OTHER  DATA APPEARING  ELSEWHERE IN  THIS
PROSPECTUS. THE PRO FORMA INFORMATION GIVES EFFECT TO THE CONVERSION OF COSTILLA
FROM A LIMITED LIABILITY COMPANY TO A CORPORATION, CERTAIN MATERIAL ACQUISITIONS
AND  THE OFFERINGS AND THE APPLICATION  OF THE ESTIMATED NET PROCEEDS THEREFROM.
SEE "-- SIGNIFICANT  ACQUISITIONS," "THE COMPANY  -- CORPORATE  REORGANIZATION,"
AND  "USE OF PROCEEDS." AS USED HEREIN, REFERENCES TO THE COMPANY OR TO COSTILLA
ARE TO COSTILLA ENERGY, INC.  AND ITS SUBSIDIARIES. UNLESS OTHERWISE  INDICATED,
THE  INFORMATION  IN THIS  PROSPECTUS  ASSUMES THE  UNDERWRITERS' OVER-ALLOTMENT
OPTION WITH RESPECT TO THE COMMON STOCK OFFERING WILL NOT BE EXERCISED.  CERTAIN
OIL AND GAS TERMS USED IN THIS PROSPECTUS ARE DEFINED IN THE "GLOSSARY" INCLUDED
HEREIN.  CERTAIN  TERMS USED  IN  CONNECTION WITH  THE  NOTES ARE  DEFINED UNDER
"DESCRIPTION OF  NOTES  --  CERTAIN DEFINITIONS."  "ADJUSTED  EBITDA,"  AS  USED
HEREIN,  MEANS  NET INCOME  (LOSS), PLUS  INTEREST, INCOME  TAXES, DEPRECIATION,
DEPLETION AND AMORTIZATION, EXPLORATION AND ABANDONMENT COSTS AND  EXTRAORDINARY
LOSS FROM EXTINGUISHMENT OF DEBT.
    
 
                                  THE COMPANY
 
   
    Costilla  is  an  independent  energy company  engaged  in  the exploration,
acquisition and development  of oil  and gas properties.  The Company's  primary
operations are in the Permian Basin area of Texas and New Mexico, the Gulf Coast
and  the Rocky  Mountain regions. The  Company's strategy  focuses on increasing
reserves through  a  targeted  exploration  program,  the  exploitation  of  its
existing  properties  and  selective  property  acquisitions.  In  addition, the
Company recently acquired an  interest in an entity  which has a concession  for
the  development of  mineral interests  in the  Republic of  Moldova, in Eastern
Europe. The Company also has minor  interests in the domestic gas gathering  and
transmission business.
    
 
   
    The  Company's  predecessor began  operating in  1988  with the  strategy of
acquiring and exploiting undervalued oil and gas properties, and at December 31,
1992 had net proved reserves  of 4.7 MMBOE. Since  January 1, 1993, the  Company
has  successfully closed seven  transactions for an  aggregate purchase price of
approximately $101 million. As of April 1, 1996, the Company had total estimated
net proved reserves of 16.5 Mmbbls of oil and 112.9 Bcf of gas, aggregating 35.3
MMBOE, with a  PV-10 Value of  approximately $179.5 million,  assuming the  1996
Acquisition  (as defined below) had occurred at  April 1, 1996. The Company also
has a  substantial  undeveloped acreage  position  consisting of  180,704  gross
(165,166  net) acres at June  30, 1996. The Company  has identified in excess of
200 drilling locations of which 78 are included in its proved reserves.
    
 
   
    Costilla  has  in-house  exploration   expertise  which  uses  3-D   seismic
technology  as  a  primary  tool  to  identify  drilling  opportunities  and has
experienced high rates of  success in each  of its first  two major 3-D  seismic
drilling  programs. Since 1994, the Company has  drilled 26 wells based on these
3-D surveys,  23  of  which  have been  productive.  The  Company  has  recently
completed  two additional 3-D surveys and intends to commence drilling on one of
these acreage blocks in the second half of 1996. The Company currently plans  to
drill 81 wells through 1997 based on its 3-D surveys.
    
 
   
    Since   1993,  Costilla  has  generated   significant  growth  in  reserves,
production and  Adjusted  EBITDA. The  Company  increased its  estimated  proved
reserves from 6.0 MMBOE at December 31, 1993 to 35.3 MMBOE at April 1, 1996 (pro
forma  for the 1996 Acquisition), representing  a compound annual growth rate of
114%. This reserve growth has been achieved at an average all-in finding cost of
$3.60 per BOE over such period, a level which the Company believes is lower than
industry averages. Concurrently,  the Company  increased its  average net  daily
production  from 827 BOE for the year ended  December 31, 1993 to 10,703 BOE for
the three months  ended March  31, 1996 (pro  forma for  the 1996  Acquisition),
representing a compound annual growth rate of 195%. Adjusted EBITDA increased at
a  240% compound annual growth rate from  $1.8 million for 1993 to $20.8 million
for 1995 (pro forma for the 1995 Acquisition and the 1996 Acquisition).
    
 
                                       3
<PAGE>
                               BUSINESS STRATEGY
 
   
    The Company's strategy is to increase  its oil and gas reserves,  production
and  cash flow from operations through  a two-pronged approach which combines an
active exploration program  using 3-D seismic  and other technological  advances
with the acquisition and exploitation of producing properties. The Company seeks
to  reduce its operating and commodity risks by holding a geographically diverse
portfolio of properties,  the reserves attributable  to which are  approximately
balanced  between oil and gas. The Company  also seeks to manage the elements of
its business strategy  through the  operation of  a significant  portion of  its
properties,  the use of a  rate of return analysis  and the direct marketing and
hedging of its oil  and gas production. The  elements of the Company's  strategy
may be further described as follows:
    
 
   
- -   EXPLORATION   EFFORTS.     The  Company  uses   extensive  geological  and
    geophysical analysis  to carefully  focus its  3-D seismic  surveys.  This
    focus  allows the Company to successfully direct the size and scope of its
    exploration program in order  to improve the  likelihood of success  while
    managing  overall exploration costs. The Company's exploration efforts are
    concentrated currently on  known producing regions.  The Company plans  to
    drill 24 exploratory wells during the last half of 1996 and 36 exploratory
    wells in 1997. Capital budgeted for exploration activities is $8.1 million
    for the last six months of 1996 and $10.8 million for 1997.
    
 
   
- -   EXPLOITATION  ACTIVITIES.    The  Company  is  actively  pursuing numerous
    exploitation opportunities within its existing properties, including areas
    where no proved reserves  are currently assigned. Exploitation  activities
    currently  in  progress  include a  carbon  dioxide  flood, recompletions,
    workovers,  infill  and  horizontal  drilling  and  a  secondary  recovery
    project.  The Company's capital budget for such activities is $8.5 million
    for the last six months of 1996 and $9.2 million for 1997, which  includes
    the  drilling of 12 development wells in  1996 and 13 development wells in
    1997.
    
 
- -   PROPERTY ACQUISITIONS.  The Company seeks to acquire producing  properties
    where  it has identified opportunities to increase production and reserves
    through both  exploitation and  exploration  activities. The  Company  has
    increased  the  value of  its  acquisitions by  aggressively  managing the
    operations of existing proved  properties and by successfully  identifying
    and  developing  previously  unproved reserves  on  acquired  acreage. The
    Company seeks to acquire reserves  which will fit its existing  portfolio,
    are  generally not  being actively  marketed and  where a  negotiated sale
    would be the method of  purchase. The Company does  not rely on major  oil
    company divestitures or property auctions.
 
- -   PROPERTY  DIVERSIFICATION.  The  Company holds a portfolio  of oil and gas
    properties located in  the Permian  Basin, the  Gulf Coast  and the  Rocky
    Mountain  regions. The Company believes  that by conducting its activities
    in distinct  regions  it is  able  to  reduce commodity  price  and  other
    operational risks. The Company's Moldovan interest is an extension of this
    strategy  and  can  be  characterized by  low  initial  costs, significant
    reserve potential  and the  availability  of technical  data that  may  be
    further developed by the Company.
 
   
- -   CONTROL  OF  OPERATIONS.   The  Company  prefers  to operate  and  own the
    majority working  interest  in its  properties.  This allows  the  Company
    greater  control over future development, drilling, completing and lifting
    costs and marketing of production. At April 1, 1996, the Company  operated
    wells  constituting approximately 65% of its  total PV-10 Value (pro forma
    for the 1996 Acquisition).
    
 
                                       4
<PAGE>
                            SIGNIFICANT ACQUISITIONS
 
   
    1995 ACQUISITION.  In  a $46.6 million acquisition  completed in June  1995,
the  Company acquired a group  of oil and gas  properties located in the Permian
Basin, Gulf Coast and  Rocky Mountain regions. At  the date of acquisition,  the
net  proved reserves included 7.1 Mmbbls of oil and 44.1 Bcf of gas, aggregating
14.4 MMBOE.  From the  date of  acquisition until  March 31,  1996, the  Company
produced  1.1  MMBOE from  the acquired  properties  and sold  a portion  of the
acquired properties for approximately  $3.6 million. At April  1, 1996, the  net
proved  reserves  of  the remaining  properties  were 13.4  MMBOE.  The acquired
properties also included 103,010 gross (93,786 net) undeveloped acres.
    
 
   
    1996 ACQUISITION.  In June 1996, the Company acquired a group of oil and gas
properties located primarily  in the Permian  Basin and Gulf  Coast regions  for
approximately  $42.5  million.  This acquisition  included  properties  with net
proved reserves at  April 1,  1996 of 5.0  Mmbbls of  oil and 33.5  Bcf of  gas,
aggregating  10.6  MMBOE. The  acquired  properties also  included  40,092 gross
(14,512 net) undeveloped acres and a pipeline located in Pennsylvania which  had
an allocated purchase price of $3.5 million.
    
 
                              DRILLING ACTIVITIES
 
   
    Exploration  efforts since  January 1,  1996 include  the drilling  of eight
wells located on  the Company's  Edwards/McElroy Ranch Prospect  in the  Permian
Basin.  While two of such wells are in various stages of drilling or completion,
the remaining  six  wells  have  been  completed  as  producers.  Three  of  the
productive  wells  have  resulted  in  separate  field  discoveries  which  have
confirmed the Company's  seismic interpretation  of a  significant trend.  Since
beginning  operations on  this prospect, the  Company has  drilled ten producing
wells and  one dry  hole. As  a  result, the  Company has  identified up  to  75
additional  drilling locations,  three of  which are  included in  the Company's
proved reserves.
    
 
   
    The Company  has also  continued  drilling in  the McGyver-Green  Acres  3-D
Prospect.  Since commencing activity  in this prospect in  July 1994 the Company
has drilled 15 wells, of  which 12 have been  successful. During June 1996,  the
average  daily  production  from  the  producing  wells  in  this  prospect  was
approximately 83 BOE per well. The Company has identified 41 additional drilling
locations in the McGyver-Green Acres Prospect,  14 of which are included in  the
Company's proved reserves.
    
 
   
    The  Company has  also drilled and  completed nine development  wells in the
Permian Basin and Gulf Coast regions since the beginning of 1996. Currently, the
Company's principal exploitation  activities include a  carbon dioxide flood  in
the  East Goldsmith  Unit, infill  drilling primarily  in the  Permian Basin and
horizontal drilling in the Susan Peak Field.
    
 
                                       5
<PAGE>
                                  THE OFFERING
 
   
<TABLE>
<S>                                           <C>
Securities Offered..........................  $100,000,000  aggregate  principal  amount  of
                                                      %  Senior Subordinated  Notes due 2006
                                              of the Company (the "Notes").
Maturity Date...............................  , 2006.
Interest Payment Dates......................  and         , commencing         , 1997.
Optional Redemption.........................  On or after           , 2001, the Company  may
                                              redeem  the Notes, in whole or in part, at the
                                              redemption  prices  set  forth  herein,   plus
                                              accrued  and unpaid  interest, if  any, to the
                                              date  of   redemption.   Notwithstanding   the
                                              foregoing,  at any time on or before         ,
                                              1999, the Company may redeem up to 30% of  the
                                              original  aggregate  principal  amount  of the
                                              Notes with  the  net  proceeds  of  an  Equity
                                              Offering  (as defined herein)  at a redemption
                                              price equal to     % of  the principal  amount
                                              thereof,  plus accrued and unpaid interest, if
                                              any, to the date of redemption, provided  that
                                              at   least  70%  of   the  original  aggregate
                                              principal   amount   of   the   Notes   remain
                                              outstanding immediately after such redemption.
                                              See   "Description   of   Notes   --  Optional
                                              Redemption."
Mandatory Redemption........................  None, except at maturity on         , 2006.
Ranking.....................................  The   Notes   will   be   general    unsecured
                                              obligations  of  the Company,  subordinated in
                                              right of payment  to all  existing and  future
                                              Senior Indebtedness of the Company, which will
                                              include  borrowings under the Credit Facility.
                                              At June 30, 1996, on  a pro forma basis  after
                                              giving effect to the Corporate Reorganization,
                                              the  Offerings and the  application of the net
                                              proceeds therefrom, the Company would have had
                                              $0.4 million of Senior Indebtedness. The Notes
                                              also will be  effectively subordinated to  all
                                              indebtedness  and  other  liabilities  of  the
                                              Company's subsidiaries until such subsidiaries
                                              (the   'Subsidiaries   Guarantors")    deliver
                                              Subsidiary Guarantees to fully and
                                              unconditionally   guarantee  the  Notes  on  a
                                              senior  subordinated  basis  (the  "Subsidiary
                                              Guarantees").    At   June   30,   1996,   the
                                              subsidiaries'  total  liabilities  were   $6.5
                                              million,   all   of   which   were   operating
                                              liabilities.  The   indenture  requires   each
                                              Subsidiary  to deliver  a Subsidiary Guarantee
                                              as  a   condition   to   its   incurrence   of
                                              Indebtedness (other than intercompany
                                              Indebtedness).  At the date  of the Indenture,
                                              there will  be no  Subsidiary Guarantees.  See
                                              "Description  of  Notes --  Subordination" and
                                              "-- Subsidiary Guarantees."
</TABLE>
    
 
                                       6
<PAGE>
 
   
<TABLE>
<S>                                           <C>
Change of Control...........................  Upon a Change of Control (as defined  herein),
                                              the  Company will be required to make an offer
                                              to repurchase all outstanding Notes at 101% of
                                              the principal amount thereof plus accrued  and
                                              unpaid  interest thereon, if  any, to the date
                                              of repurchase.  See "Description  of Notes  --
                                              Repurchase  at the Option of Holders -- Change
                                              of Control."
Covenants...................................  The Indenture pursuant to which the Notes will
                                              be issued  (the  "Indenture")  will  restrict,
                                              among  other things, the  Company's ability to
                                              incur additional  indebtedness, pay  dividends
                                              or  make  certain  other  restricted payments,
                                              incur  liens   to   secure   PARI   PASSU   or
                                              subordinated  indebtedness, engage in any sale
                                              and  leaseback  transaction,  sell  stock   of
                                              subsidiaries,  apply net proceeds from certain
                                              asset sales,  merge  or consolidate  with  any
                                              other  person, sell,  assign, transfer, lease,
                                              convey or otherwise  dispose of  substantially
                                              all  of the assets of  the Company, enter into
                                              certain transactions with affiliates, or incur
                                              indebtedness that is  subordinate in right  of
                                              payment  to any Senior Indebtedness and senior
                                              in right of payment to the Notes.
Common Stock Offering.......................  Concurrently  with  the  Notes  Offering,  the
                                              Company is offering 4,000,000 shares of Common
                                              Stock   to  the  public.   See  "Common  Stock
                                              Offering." The closings of the Notes  Offering
                                              and   the  Common  Stock   Offering  are  each
                                              conditioned  upon  the  consummation  of   the
                                              other.
Use of Proceeds.............................  The Company intends to use the net proceeds of
                                              the  Notes  Offering,  together  with  the net
                                              proceeds of the Common  Stock Offering (i)  to
                                              repay   existing  indebtedness,  (ii)  to  pay
                                              certain costs incurred in connection with  the
                                              Corporate  Reorganization (as defined herein),
                                              including   redeeming    certain    membership
                                              interests  of  the  Company's  predecessor and
                                              (iii) for general corporate purposes. See "Use
                                              of Proceeds."
</TABLE>
    
 
                                  RISK FACTORS
 
    See "Risk  Factors" for  a  discussion of  certain  factors that  should  be
considered in evaluating an investment in the Notes.
 
                                       7
<PAGE>
                         SUMMARY FINANCIAL INFORMATION
 
   
    The  following table  sets forth  certain summary  historical and  pro forma
financial data of  the Company.  The historical  information should  be read  in
conjunction  with the  Consolidated Financial  Statements and  the notes thereto
included  elsewhere  in  this  Prospectus.  The  Company  acquired   significant
producing  oil  and gas  properties in  certain of  the periods  presented which
affect the comparability of the historical financial and operating data for  the
periods  presented. The pro forma information should be read in conjunction with
the  Pro  Forma  Condensed  Financial  Statements  and  notes  thereto  included
elsewhere  in this Prospectus. Neither the  historical results nor the pro forma
results are  necessarily  indicative  of  the  Company's  future  operations  or
financial results.
    
 
   
<TABLE>
<CAPTION>
                                                                 YEAR ENDED DECEMBER 31,               SIX MONTHS ENDED JUNE 30,
                                                        ------------------------------------------  -------------------------------
                                                                  HISTORICAL             PRO FORMA       HISTORICAL       PRO FORMA
                                                        -------------------------------  ---------  --------------------  ---------
                                                          1993       1994       1995      1995(1)     1995       1996      1996(1)
                                                        ---------  ---------  ---------  ---------  ---------  ---------  ---------
                                                                     (IN THOUSANDS, EXCEPT RATIOS AND PER SHARE DATA)
<S>                                                     <C>        <C>        <C>        <C>        <C>        <C>        <C>
STATEMENT OF OPERATIONS DATA:
  Revenues............................................  $   4,397  $   7,836  $  21,816  $  52,637  $   5,573  $  19,525  $  28,748
  Expenses:
    Oil and gas production............................      1,688      2,351     10,355     26,937      2,413      8,278     13,295
    General and administrative........................        952      1,184      3,571      4,850      1,008      2,809      3,010
    Exploration and abandonments......................        218        793      1,650      2,761      1,007        308        555
    Depreciation, depletion and amortization..........        884      1,847      5,958     14,176      1,367      4,620      6,981
    Interest..........................................        605      1,458      4,591     11,635      1,046      4,156      5,817
    Other.............................................         --         --          2          2         --         --         --
  Net income (loss) before income taxes and
   extraordinary item.................................         50        203     (4,311)    (7,724)    (1,268)      (646)      (910)
  Pro forma earnings (loss) per common share..........         --         --         --      (0.78)        --         --      (0.09)
  Pro forma weighted average common shares
   outstanding........................................         --         --         --      9,861         --         --     10,000
STATEMENT OF CASH FLOWS DATA:
  Net cash provided by (used in):
    Operating activities..............................  $     322  $   1,527  $   6,366         --  $  (3,040) $    (122)        --
    Investing activities..............................     (6,731)   (12,146)   (62,467)        --    (57,773)   (49,723)        --
    Financing activities..............................      6,315     10,618     58,830         --     62,094     48,143         --
OTHER FINANCIAL DATA:
  Capital expenditures................................  $   6,862  $  11,868  $  62,220         --  $  57,773  $  49,723         --
  Adjusted EBITDA (2).................................      1,757      4,301      7,888  $  20,848      2,152      8,438  $  12,443
  Adjusted EBITDA/interest expense (2)................        2.9x       2.9x       1.7x       1.8x       2.1x       2.0x       2.1x
  Ratio of earnings to fixed charges (3)..............        1.0        1.1         --         --         --         --         --
BALANCE SHEET DATA (AS OF PERIOD END):
  Working capital.....................................  $   1,612  $   1,081  $   2,496         --         --  $   4,266  $  13,757
  Total assets........................................     13,365     24,904     87,367         --         --    135,047    146,434
  Total debt..........................................     12,006     23,613     71,494         --         --    122,365    100,365
  Redeemable members' capital.........................         --         --     12,278         --         --     13,557         --
  Members' capital....................................         51       (747)    (8,147)        --         --    (11,712)        --
  Pro forma stockholders' equity......................         --         --         --         --         --         --     35,232
  ACNTA (4)...........................................                                                                      200,923
  Ratio of ACNTA to total debt........................         --         --         --         --         --         --        2.0x
</TABLE>
    
 
- ------------------------------
   
(1)  Assumes  that  the 1995  Acquisition, the  1996 Acquisition,  the Corporate
     Reorganization (as defined in "The Company-- Corporate Reorganization") and
     the Offerings and the application of proceeds therefrom had taken place  on
     June  30, 1996 for  purposes of the  Balance Sheet Data  (to the extent not
     already reflected) and as of January  1, 1995 for purposes of Statement  of
     Operations Data and Other Financial Data.
    
   
(2)  Adjusted  EBITDA and the  ratio of Adjusted EBITDA  to interest expense are
     presented because of  their wide  acceptance as financial  indicators of  a
     company's  ability  to  service or  incur  debt. Adjusted  EBITDA  (as used
     herein) is  calculated  by  adding interest,  income  taxes,  depreciation,
     depletion   and  amortization,   exploration  and   abandonment  costs  and
     extraordinary loss  resulting from  extinguishment of  debt to  net  income
     (loss).  The ratio of Adjusted EBITDA  to interest expense is calculated by
     dividing Adjusted EBITDA  by interest. Interest  includes interest  expense
     accrued  and amortization of deferred  financing costs. Adjusted EBITDA and
     the ratio of Adjusted EBITDA to  interest expense should not be  considered
     as  alternatives  to  earnings  (loss), or  operating  earnings  (loss), as
     defined by generally accepted accounting  principles, as indicators of  the
     Company's financial performance or to cash flow as a measure of liquidity.
    
   
(3)  For  purposes  of  calculating  the ratio  of  earnings  to  fixed charges,
     "earnings" are net income (loss)  before extraordinary loss resulting  from
     extinguishment  of debt, plus income taxes and fixed charges. Fixed charges
     are  comprised  of  interest  on  indebtedness,  amortization  of  deferred
     financing  costs,  and that  portion of  operating  lease expense  which is
     deemed  to  be  representative  of   an  interest  factor.  Earnings   were
     insufficient  to cover fixed charges by $4,311,000, $1,268,000 and $646,000
     for the historical periods ended December 31, 1995, June 30, 1995 and  June
     30,  1996,  respectively, and  $7,724,000 and  $910,000  for the  pro forma
     periods ended December 31, 1995 and June 30, 1996, respectively.
    
   
(4)  ACNTA means Adjusted  Consolidated Net  Tangible Assets as  defined in  the
     Indenture. See "Description of Notes-- Certain Definitions."
    
 
                                       8
<PAGE>
                              SUMMARY RESERVE DATA
 
   
<TABLE>
<CAPTION>
                                                                 AS OF DECEMBER 31,           AS OF APRIL 1, 1996
                                                           -------------------------------  ------------------------
                                                             1993       1994       1995      ACTUAL    PRO FORMA(1)
                                                           ---------  ---------  ---------  ---------  -------------
<S>                                                        <C>        <C>        <C>        <C>        <C>
ESTIMATED PROVED RESERVES (2):
  Oil (MBbls)............................................      2,365      4,009     10,788     11,479        16,476
  Gas (Mmcf).............................................     21,619     27,512     78,152     79,420       112,920
  MBOE...................................................      5,968      8,594     23,813     24,716        35,296
  Percent of proved developed reserves...................       67.0%      62.3%      76.1%      73.9%         78.2%
  Present value of estimated future net cash flow, before
   income taxes, discounted at 10% (in thousands)........  $  26,377  $  36,779  $ 113,296  $ 129,091   $   179,527
  Reserve life index (in years) (3)......................       19.7       14.4       13.6         --            --
RESERVE REPLACEMENT DATA:
  Production replacement ratio (4).......................        513%       549%       969%        --            --
  All-in finding costs per BOE (5).......................  $    4.31  $    3.67  $    3.43  $    2.84   $      3.72
</TABLE>
    
 
- ------------------------------
 
   
(1)  Gives effect to the 1996 Acquisition as if such transaction had occurred as
    of April 1, 1996.
    
 
   
(2) Estimates of net proved oil and gas  reserves at April 1, 1996 are based  on
    reports  prepared by Williamson  Petroleum Consultants, Inc. ("Williamson"),
    independent petroleum engineers. The 1995 reserve estimates were prepared by
    the Company and such estimates of gross reserves with respect to certain  of
    the  Company's  producing properties  were subject  to  a limited  review by
    Williamson. Prior reserve estimates are based on information compiled by the
    Company. See "Risk Factors  -- Uncertainty of  Estimates of Proved  Reserves
    and  Future  Net  Revenues" and  "Business  and  Properties --  Oil  and Gas
    Reserves."
    
 
(3) Calculated by dividing year-end proved reserves by annual production for the
    most recent year.
 
(4) Calculated by dividing reserve  additions through acquisitions of  reserves,
    extensions  and discoveries and revisions during  the year by production for
    such year.
 
   
(5) The average  all-in finding costs  over the period  January 1, 1993  through
    March 31, 1996 (pro forma for the 1996 Acquisition) was $3.60 per BOE.
    
 
                             SUMMARY OPERATING DATA
 
   
<TABLE>
<CAPTION>
                                                             YEAR ENDED DECEMBER 31,
                                                  ----------------------------------------------
                                                                                                  SIX MONTHS ENDED JUNE 30,
                                                            HISTORICAL             PRO FORMA(1)              1996
                                                  -------------------------------  -------------  --------------------------
                                                    1993       1994       1995         1995        ACTUAL     PRO FORMA(1)
                                                  ---------  ---------  ---------  -------------  ---------  ---------------
<S>                                               <C>        <C>        <C>        <C>            <C>        <C>
PRODUCTION DATA:
  Oil (MBbls)...................................        158        330        950        2,085          709           990
  Gas (Mmcf)....................................        865      1,600      4,806       11,985        3,504         5,345
  MBOE..........................................        302        597      1,751        4,083        1,293         1,881
AVERAGE SALES PRICE PER UNIT:
  Oil (per Bbl).................................  $   16.93  $   15.25  $   15.53    $   15.75    $   18.99     $   18.26
  Gas (per Mcf).................................       1.82       1.63       1.45         1.59         1.91          1.87
COSTS PER BOE:
  Production costs, including severance taxes
   (2)..........................................  $    5.59  $    3.94  $    5.91    $    6.60    $    6.40     $    7.07
  Depreciation, depletion and amortization......       2.93       3.09       3.40         3.51         3.57          3.71
</TABLE>
    
 
- ------------------------------
 
(1)  Gives effect to  the 1995 Acquisition  and the 1996  Acquisition as if such
    transactions had occurred as of January 1, 1995.
 
   
(2) Production costs per BOE in 1995 and for the six months ended June 30,  1996
    were  unusually high as  a result of relatively  high workover expenses with
    respect to properties acquired in the 1995 Acquisition which did not produce
    related production improvements until subsequent periods. Additionally,  the
    Company's 1995 production costs were adversely affected by expenses incurred
    in  connection  with plugging  wells  to comply  with  applicable regulatory
    requirements.
    
 
                                       9
<PAGE>
                                  RISK FACTORS
 
    PRIOR  TO  MAKING  AN  INVESTMENT  DECISION,  PROSPECTIVE  INVESTORS  SHOULD
CONSIDER  FULLY,  TOGETHER  WITH  THE   OTHER  INFORMATION  CONTAINED  IN   THIS
PROSPECTUS, THE FOLLOWING FACTORS.
 
SIGNIFICANT LEVERAGE AND DEBT SERVICE
 
   
    As  of  June 30,  1996, as  adjusted for  the Corporate  Reorganization, the
Offerings and the application of the net proceeds therefrom, the Company's total
debt and stockholders' equity would have been $100.4 million and $35.2  million,
respectively. See "Capitalization." In addition, the Company may currently incur
additional indebtedness under its Credit Facility (as defined under "Description
of   Other  Indebtedness").  Immediately  following   the  consummation  of  the
Offerings, the  Credit  Facility  will  afford  the  Company  $50.0  million  of
available  borrowing  capacity, none  of which  is expected  to be  necessary to
finance the Company's existing business  plan. See "Management's Discussion  and
Analysis  of  Financial Condition  and Results  of  Operations --  Liquidity and
Capital Resources" and "Description of Other Indebtedness."
    
 
   
    The Company's level of indebtedness  will have several important effects  on
its future operations, including (i) a substantial portion of the Company's cash
flow  from  operations must  be  dedicated to  the  payment of  interest  on its
indebtedness and  will  not be  available  for other  purposes,  (ii)  covenants
contained  in the  Credit Facility  and the  Indenture governing  the Notes will
require the Company to meet certain financial tests, and other restrictions  may
limit  its ability to  borrow additional funds  or to dispose  of assets and may
affect the Company's flexibility  in planning for, and  reacting to, changes  in
its  business, including possible acquisition activities and (iii) the Company's
ability to  obtain  additional financing  in  the future  for  working  capital,
capital expenditures, acquisitions, general corporate purposes or other purposes
may  be  impaired.  See  "Management's  Discussion  and  Analysis  of  Financial
Condition and Results of Operations -- Liquidity and Capital Resources."
    
 
   
    The Company's ability to meet its debt service obligations and to reduce its
total indebtedness  will be  dependent upon  the Company's  future  performance,
which  will be subject to general economic conditions and to financial, business
and other factors  affecting the operations  of the Company,  many of which  are
beyond  its control. Earnings  were insufficient to cover  fixed charges by $4.3
million and $0.6 million  for the year  ended December 31,  1995 and six  months
ended June 30, 1996, respectively, and $7.7 million and $0.9 million for the pro
forma  year  ended  December  31,  1995 and  six  months  ended  June  30, 1996,
respectively. Based upon the  current and anticipated  level of operations,  the
Company  believes, however,  that its cash  flow from  operations, together with
amounts available under its Credit Facility and its other sources of  liquidity,
will  be adequate to meet its anticipated requirements in the foreseeable future
for working  capital,  capital  expenditures, interest  payments  and  scheduled
principal  payments.  There can  be no  assurance,  however, that  the Company's
business will continue to generate cash flow at or above current levels. If  the
Company is unable to generate sufficient cash flow from operations in the future
to  service its debt,  it may be required  to refinance all or  a portion of its
existing debt, including the Notes, or to obtain additional financing. There can
be no  assurance  that  any such  refinancing  would  be possible  or  that  any
additional  financing  could be  obtained.  The inability  to  obtain additional
financing could have a  material adverse effect on  the Company. For example,  a
default  by  the Company  under the  terms of  the Indenture  could result  in a
default under the terms of the Credit Facility.
    
 
SUBORDINATION OF NOTES AND SUBSIDIARY GUARANTEES
 
   
    The Notes  will be  subordinated in  right of  payment to  all existing  and
future  Senior Indebtedness of the Company, including all indebtedness under the
Credit Facility. As  of June  30, 1996,  after giving  pro forma  effect to  the
Corporate  Reoganization, the Offerings and the  application of the net proceeds
therefrom,  the  Company  would  have  had  $0.4  million  Senior   Indebtedness
outstanding  and will  have $50.0 million  available under  the Credit Facility,
which, if borrowed, would  be included as Senior  Indebtedness. In the event  of
bankruptcy,  liquidation  or  reorganization  of  the  Company,  the  assets  of
    
 
                                       10
<PAGE>
the Company will be  available to pay  obligations on the  Notes only after  all
Senior  Indebtedness of the Company has been paid  in full, and there may not be
sufficient funds  remaining to  pay  amounts due  on any  or  all of  the  Notes
outstanding. See "Description of Notes -- Subordination."
 
   
    The  Indenture does not require the Subsidiaries to guarantee the payment of
the Notes unless  the Subsidiaries incur  Indebtedness (other than  intercompany
Indebtedness).  The  Indenture prohibits  Subsidiaries  that are  not Subsidiary
Guarantors  from  incurring   Indebtedness.  The  Notes   will  be   effectively
subordinated to claims of creditors (other than the Company) of the Subsidiaries
that   are  not   Subsidiary  Guarantors,  including   trade  creditors,  taxing
authorities and tort claimants. Such  creditors generally will have priority  as
to  the assets of such Subsidiaries over  the claims and equity interests of the
Company and, thereby  indirectly, the  holders of indebtedness  of the  Company,
including  the Notes.  At June  30, 1996,  on a  pro forma  basis, the Company's
Subsidiaries had  $6.5  million of  liabilities,  all of  which  were  operating
liabilities.  Any Subsidiary Guarantees will be subordinated in right of payment
to all existing and future Guarantor Senior Indebtedness (as herein defined)  of
the  Subsidiary  Guarantors. On  the  date of  the  Indenture there  will  be no
Subsidiary  Guarantees.  See  "Description   of  Notes  --  Subordination"   and
"Description of Notes -- Incurrence of Indebtedness and Preferred Stock."
    
 
SUBSIDIARY GUARANTEES MAY TERMINATE; FRAUDULENT CONVEYANCE CONSIDERATIONS
RELATING TO SUBSIDIARY GUARANTEES
 
   
    The  Indenture does not require any Subsidiary to guarantee the Notes unless
such Subsidiary incurs Indebtedness  (other than intercompany Indebtedness).  On
the  date  of the  Indenture  there will  be  no Subsidiary  Guarantees. Various
fraudulent conveyance laws have been enacted for the protection of creditors and
may be used by  a court of  competent jurisdiction to  subordinate or avoid  any
Subsidiary  Guarantee that may be delivered. To  the extent that a court were to
find that (x)  a Subsidiary Guarantee  was incurred with  the intent to  hinder,
delay  or  defraud  any  present  or future  creditor  or  that  such Subsidiary
Guarantor contemplated insolvency with a design  to favor one or more  creditors
to the exclusion in whole or in part of others or (y) a Subsidiary Guarantor did
not  receive fair consideration  or reasonably equivalent  value for issuing its
Subsidiary Guarantee and, at the time  it issued the Subsidiary Guarantee,  such
Subsidiary  Guarantor (i) was  insolvent or rendered insolvent  by reason of the
issuance of the Subsidiary Guarantee, (ii) was  engaged or about to engage in  a
business  or  transaction  for which  the  remaining assets  of  such Subsidiary
Guarantor constituted unreasonably small capital or (iii) intended to incur,  or
believed that it would incur, debts beyond its ability to pay such debts as they
matured, a court could avoid or subordinate the Subsidiary Guarantee in favor of
such  Subsidiary  Guarantor's  other  creditors.  Among  other  things,  a legal
challenge of the  Subsidiary Guarantee  issued by such  Subsidiary Guarantor  on
fraudulent  conveyance grounds  may focus on  the benefits, if  any, realized by
such Subsidiary Guarantor  as a result  of the  issuance by the  Company of  the
Notes.  To  the extent  the  Subsidiary Guarantee  was  avoided as  a fraudulent
conveyance or held unenforceable for any other reason, the holders of the  Notes
would  cease to have  any claim against  such Subsidiary Guarantor  and would be
creditors solely of the Company  and any Subsidiary Guarantors whose  Subsidiary
Guarantees  were not avoided or held unenforceable. In such event, the claims of
the holders of the Notes against  the issuer of an invalid Subsidiary  Guarantee
would  be subject  to the  prior payment of  all liabilities  of such Subsidiary
Guarantor. There can be no assurance that, after providing for all prior claims,
there would be sufficient  assets to satisfy  the claims of  the holders of  the
Notes relating to any avoided portions of any of the Subsidiary Guarantees.
    
 
   
    The  measure of insolvency for purposes of the foregoing considerations will
vary depending upon the law applied in any such proceeding. Generally,  however,
a  Subsidiary Guarantor  may be  considered insolvent if  the sum  of its debts,
including contingent liabilities, was greater than the fair market value of  all
of  its assets  at a  fair valuation, if  the present  fair market  value of its
assets was less  than the  amount that  would be  required to  pay its  probable
liability  on  its existing  debts,  including contingent  liabilities,  as they
become absolute and mature, or  if it had insufficient  capital to carry on  its
business.
    
 
                                       11
<PAGE>
POTENTIAL INABILITY TO FUND A CHANGE OF CONTROL OFFER
 
   
    The  Indenture provides that upon the occurrence of a Change of Control, the
Company is required to offer to repurchase  any or all of the outstanding  Notes
at  a price equal  to 101% of  the aggregate principal  amount thereof, together
with accrued and unpaid interest, if any, to the date of purchase. Generally,  a
"Change  of Control" includes any person or  group other than Cadell S. Liedtke,
Michael J. Grella and Henry G.  Musselman, the Chairman of the Board,  President
and Executive Vice President of the Company, respectively, acquiring 50% or more
of  the voting securities of the Company,  and certain other events. If a Change
of Control occurs, there  is no assurance that  the Company will have  available
funds  sufficient to pay for the Notes tendered for repurchase. See "Description
of Notes -- Repurchase at the Option of Holders -- Change of Control."
    
 
   
    If an offer to repurchase  is required to be made  and the Company does  not
have  available funds  sufficient to pay  for Notes tendered  for repurchase, an
event of default would occur under the Indenture. The occurrence of an event  of
default  could result in  the acceleration of  maturity of the  Notes and of all
amounts due  under the  Credit  Facility. In  addition,  the Change  of  Control
covenant  in the Indenture could  have the effect of  discouraging a takeover of
the Company by making such an attempt potentially more expensive.
    
 
UNCERTAINTY OF ESTIMATES OF PROVED RESERVES AND FUTURE NET CASH FLOWS
 
   
    There are numerous uncertainties in estimating quantities of proved reserves
and in  projecting future  rates of  production and  the timing  of  development
expenditures,  including many  factors beyond  the control  of the  Company. The
reserve data  set forth  in this  Prospectus are  estimates only.  Although  the
Company  believes  such  estimates  to  be  reasonable,  reserve  estimates  are
imprecise and should  be expected  to change as  additional information  becomes
available.  Furthermore, estimates  of oil and  gas reserves,  of necessity, are
projections based on engineering data,  and there are uncertainties inherent  in
the  interpretation of such  data as well  as the projection  of future rates of
production and the timing of development expenditures. Reserve engineering is  a
subjective  process of estimating underground accumulations  of oil and gas that
cannot be  exactly measured,  and the  accuracy  of any  reserve estimate  is  a
function  of the  quality of  available data  and of  engineering and geological
interpretation  and  judgment.  Accordingly,   estimates  of  the   economically
recoverable  quantities of oil  and gas attributable to  any particular group of
properties, classifications  of such  reserves based  on risk  of recovery,  and
estimates  of the future net cash flows expected therefrom prepared by different
engineers or by the  same engineers at different  times may vary  substantially.
Moreover,  there can  be no  assurance that the  reserves set  forth herein will
ultimately be produced or that the proved undeveloped reserves will be developed
within the periods  anticipated. Variances from  the estimates contained  herein
could be material. In addition, the estimates of future net revenues from proved
reserves  of the Company  and the present  value thereof are  based upon certain
assumptions about production levels, prices and costs, which may not be correct.
The Company emphasizes with respect to such estimates that the discounted future
net cash flows  should not  be construed as  representative of  the fair  market
value  of the proved  oil and gas  properties belonging to  the Company, because
discounted future net cash flows are based upon projected cash flows that do not
provide for changes  in oil and  gas prices  or for escalation  of expenses  and
capital costs. The meaningfulness of such estimates is highly dependent upon the
accuracy  of  the assumptions  upon which  they were  based. Actual  results may
differ materially from  the results estimated.  Prospective purchasers of  Notes
are  cautioned not to place undue reliance  on the reserve data included in this
Prospectus.
    
 
ACQUISITION RISKS
 
    The Company's rapid growth  in recent years has  been largely the result  of
acquisitions  of  producing  properties.  The  Company  expects  to  continue to
evaluate and  pursue acquisition  opportunities  available on  terms  management
considers  favorable  to the  Company. The  successful acquisition  of producing
properties requires an assessment  of recoverable reserves,  future oil and  gas
prices, operating costs, potential environmental and other liabilities and other
factors  beyond the Company's control. Such an assessment is necessarily inexact
and its accuracy is inherently uncertain. In connection with such an assessment,
the Company  performs  a  review  of  the  subject  properties  it  believes  to
 
                                       12
<PAGE>
be  generally consistent with  industry practices. Such  a review, however, will
not reveal all existing  or potential problems,  nor will it  permit a buyer  to
become   sufficiently  familiar  with  the  properties  fully  to  assess  their
deficiencies and capabilities. Inspections may  not be performed on every  well,
and  structural and environmental  problems are not  necessarily observable even
when an  inspection is  undertaken. The  Company is  generally not  entitled  to
contractual  indemnification for preclosing liabilities, including environmental
liabilities, and generally acquires  interests in the properties  on an "as  is"
basis.
 
VOLATILITY OF OIL AND GAS PRICES
 
    The  Company's financial results and, therefore,  its ability to service its
debt, including the Notes, are significantly affected by the price received  for
the  Company's oil and gas production. Historically, the markets for oil and gas
have been volatile and may continue to be volatile in the future. Prices of  oil
and  gas are  subject to  wide fluctuations  in response  to market uncertainty,
changes in supply and demand and a  variety of additional factors, all of  which
are  beyond  the control  of  the Company.  These  factors include  domestic and
foreign political conditions, the overall level of supply of and demand for  oil
and  gas, the price of  imported oil and gas,  weather conditions, the price and
availability of alternative fuels and overall economic conditions. The Company's
future financial condition and results of operations will be dependent, in part,
upon the prices received for  the Company's oil and  gas production, as well  as
the  costs of acquiring,  finding, developing and  producing reserves. To reduce
its exposure to price risks in the sale  of its oil and gas, the Company  enters
into  hedging  arrangements from  time to  time. Although  the Company  hedges a
significant portion of its  production, any substantial  or extended decline  in
the  price of oil and gas would have  a material adverse effect on the Company's
financial condition and results of operations,  as well as reduce the amount  of
the  Company's oil and gas that could be produced economically. Moreover, if oil
and gas prices fall materially below  their current levels, the availability  of
funds  and the Company's  ability to repay outstanding  amounts under its Credit
Facility and the Notes could be materially adversely affected. See "Management's
Discussion and Analysis of Financial Condition and Results of Operations."
 
CONFLICTS OF INTEREST
 
   
    The Company has a continuing relationship with A&P Meter Sales and Services,
Inc. ("A&P"), a corporation in which  Messrs. Liedtke, Grella and Musselman  own
60.0%  of the outstanding common stock. A&P owes the Company $437,000 (including
accrued interest through December 31, 1995) pursuant to a promissory note  under
which  the Company is not  entitled to any principal  or interest payments until
December 31, 2004. A&P also owes the Company $247,000, which is represented by a
promissory note payable upon demand. See "Certain Transactions."
    
 
    Under the Company's current credit arrangements, Messrs. Liedtke, Grella and
Musselman are each  liable for  a portion of  the Company's  existing debt  (see
"Description  of Other  Indebtedness") pursuant to  limited guaranties. However,
these individuals will not  be liable for, or  guarantee amounts due under,  the
Credit Facility or the indebtedness represented by the Notes.
 
DEPENDENCE ON KEY PERSONNEL
 
   
    The  Company depends to a  large extent on the  services of Messrs. Liedtke,
Grella and Musselman. The loss of the services of any of Messrs. Liedtke, Grella
or Musselman could have a material  adverse effect on the Company's  operations.
Pursuant   to  employment  agreements  which  are   to  be  effective  upon  the
consummation of the Offerings, Messrs. Liedtke, Grella and Musselman have agreed
not to compete with  the Company for a  one-year period should they  voluntarily
leave  the Company's  employment or  should their  employment be  terminated for
cause within  the initial  three-year  term of  each employment  agreement.  The
Company believes that its success is also dependent upon its ability to continue
to employ and retain skilled technical personnel. See "Management."
    
 
CONTROL OF THE COMPANY
 
    If  the Offerings are completed, Messrs.  Liedtke, Grella and Musselman will
own directly and indirectly, in the  aggregate, 49.2% of the outstanding  Common
Stock (or 46.4% if the underwriters'
 
                                       13
<PAGE>
over-allotment  option  in  the Common  Stock  Offering is  exercised  in full).
Accordingly, Messrs.  Liedtke, Grella  and  Musselman may  be able  to  exercise
significant  influence over  the election  of directors  of the  Company and the
control of  the  Company's management,  operations  and affairs.  See  "Security
Ownership of Certain Beneficial Owners and Management."
 
FOREIGN INVESTMENT
 
    The Company's investment in Moldova involves risks typically associated with
investments  in  emerging  markets  such as  foreign  exchange  restrictions and
currency fluctuations, foreign taxation, changing political conditions,  foreign
and   domestic  monetary  and   tax  policies,  expropriation,  nationalization,
nullification,  modification  or  renegotiation  of  contracts,  war  and  civil
disturbances  and other risks that may limit or disrupt markets. In addition, if
a dispute arises in its Moldovan operations,  the Company may be subject to  the
exclusive  jurisdiction of foreign courts or may not be successful in subjecting
foreign persons to the jurisdiction of  the United States. The Company  attempts
to conduct its business and financial affairs so as to protect against political
and  economic risks  applicable to  operations in Moldova,  but there  can be no
assurance the Company will be successful in so protecting itself.
 
DRILLING RISKS
 
    Drilling involves numerous  risks, including the  risk that no  commercially
productive  oil or gas will be encountered. The cost of drilling, completing and
operating wells is often  uncertain, and drilling  operations may be  curtailed,
delayed  or cancelled as a result of  a variety of factors, including unexpected
drilling  conditions,  pressure  or  irregularities  in  formations,   equipment
failures or accidents, adverse weather conditions and shortages or delays in the
delivery  of  equipment. The  Company's future  drilling  activities may  not be
successful and, if unsuccessful, such failure may have a material adverse effect
on the Company's future results of operations and financial condition.
 
OPERATING HAZARD AND UNINSURED RISKS
 
    The Company's operations are  subject to hazards and  risks inherent in  the
drilling  for and production and transportation of oil and gas, including fires,
natural disasters, explosions, encountering formations with abnormal  pressures,
blowouts,  cratering, pipeline ruptures, and spills,  any of which can result in
loss of hydrocarbons, environmental pollution, personal injury or loss of  life,
severe  damage to and destruction  of properties of the  Company and others, and
suspension of operations. Although the Company maintains insurance coverage that
it considers to  be adequate  and customary  in the  industry, it  is not  fully
insured  against certain  of these risks,  either because such  insurance is not
available or because  of high  premium costs.  The occurrence  of a  significant
event not fully covered by insurance could have a material adverse effect on the
Company's financial condition and results of operations.
 
COMPETITION
 
    The  Company  encounters  substantial competition  in  acquiring properties,
marketing oil  and gas  and securing  trained personnel.  Many competitors  have
substantially  larger financial resources, staffs  and facilities. See "Business
and Properties -- Competition and Markets."
 
GOVERNMENT LAWS AND REGULATIONS
 
    The Company's operations are affected from  time to time in varying  degrees
by  political developments and federal, state and local laws and regulations. In
particular, oil and gas  production, operations and economics  are or have  been
significantly  affected by price controls, taxes  and other laws relating to the
oil and gas industry, by changes in  such laws and by changes in  administrative
regulations. The Company cannot predict how existing laws and regulations may be
interpreted  by enforcement agencies  or court rulings,  whether additional laws
and regulations will  be adopted, or  the effect  such changes may  have on  its
business,  financial  condition  or  results of  operations.  See  "Business and
Properties -- Regulation."
 
                                       14
<PAGE>
ENVIRONMENTAL REGULATIONS
 
    The Company's  operations are  subject to  complex and  constantly  changing
environmental   laws  and  regulations  adopted  by  federal,  state  and  local
governmental authorities. The  Company believes that  compliance with such  laws
has  had no material  adverse effect upon  the Company's operations  to date and
that the  cost of  such  compliance has  not  been material.  Nevertheless,  the
discharge  of oil, gas or other pollutants into  the air, soil or water may give
rise to significant liabilities on the part of the Company to the government and
third parties  and  may  require  the Company  to  incur  substantial  costs  of
remediation.  Moreover, the Company has agreed to indemnify sellers of producing
properties  from  whom  the  Company  has  acquired  reserves  against   certain
liabilities  for  environmental  claims  associated  with  the  properties being
purchased by the Company, including, without limitation, in connection with both
the 1995 Acquisition and  the 1996 Acquisition. No  assurance can be given  that
existing   environmental  laws  or  regulations,  as  currently  interpreted  or
reinterpreted in the future, or future laws or regulations, will not  materially
adversely  affect the Company's results of operations and financial condition or
that material indemnity claims will not  arise against the Company with  respect
to  properties  acquired  by  the  Company.  See  "Business  and  Properties  --
Environmental Matters."
 
ABSENCE OF PUBLIC MARKET
 
    There is no existing public  market for the Notes  and the Company does  not
intend  to  list the  Notes on  any national  securities exchange.  Although the
Underwriters have  advised the  Company that  they currently  intend to  make  a
market  in  the Notes,  the  Underwriters are  not obligated  to  do so  and may
discontinue such  market-making  at  any  time. Accordingly,  there  can  be  no
assurance  that  an active  market will  develop upon  completion of  this Notes
Offering or,  if developed,  that such  market will  be sustained.  The  initial
offering  price of the Notes will be determined through negotiations between the
Company and the Underwriters, and may  bear no relationship to the market  price
of  the Notes after  the Notes Offering.  Factors such as  quarterly or cyclical
variations in  the  Company's financial  condition  and results  of  operations,
variations in interest rates, future announcements concerning the Company or its
competitors,  government regulation,  general economic and  other conditions and
developments affecting the oil and gas industry could cause the market price  of
the Notes to fluctuate substantially.
 
FORWARD-LOOKING STATEMENTS
 
   
    Certain   statements  contained   in  this   Prospectus,  including  without
limitation,  statements   containing   the  words   "believes,"   "anticipates,"
"intends,"  "expects," and words of  similar import, constitute "forward-looking
statements". Such forward-looking  statements involve known  and unknown  risks,
uncertainties  and other factors that may  cause the actual results, performance
or achievements of the Company or  industry to be materially different from  any
future  results,  performance  or  achievements  expressed  or  implied  by such
forward-looking statements.  Certain  of these  factors  are discussed  in  more
detail   elsewhere  in  this  Prospectus,  including  without  limitation  under
"Prospectus Summary," "Risk Factors,"  "Management's Discussion and Analysis  of
Financial  Condition and Results of  Operations," and "Business and Properties".
Given these  uncertainties, prospective  investors are  cautioned not  to  place
undue  reliance on  such forward-looking  statements. The  Company disclaims any
obligation to update any such factors or to publicly announce the result of  any
revisions  to any of the forward-looking  statements contained herein to reflect
future events or developments.
    
 
                                       15
<PAGE>
                                  THE COMPANY
 
GENERAL
 
   
    The Company  is  an  independent  energy company  that  is  engaged  in  the
acquisition,   exploration,  exploitation   and  development  of   oil  and  gas
properties. The Company's primary operations are in the Permian Basin, the  Gulf
Coast  and the Rocky Mountain regions. The Company recently acquired an interest
in an entity which has a concession for the development of mineral interests  in
the Republic of Moldova, in Eastern Europe. The Company also has minor interests
in the domestic gas gathering and transmission business.
    
 
CORPORATE REORGANIZATION
 
   
    Costilla  was  incorporated  in Delaware  in  June 1996  to  consolidate and
continue the activities previously conducted by Costilla Energy, L.L.C., a Texas
limited liability company  (the "LLC"),  and its wholly  owned subsidiaries,  to
acquire  the assets  of CSL Management  Corporation ("CSL")  (which owns certain
office equipment  used by  the Company),  and  to acquire  the stock  of  Valley
Gathering Company ("Valley"). Costilla has been formed solely for the purpose of
conducting  the Offerings, and has not commenced operations. Both CSL and Valley
are owned by Messrs. Liedtke, Grella and Musselman. See "Certain Transactions."
    
 
   
    Contemporaneously with the  closings of  the Offerings:  (1) the  redeemable
membership  interests of NationsBanc  Capital Corp. ("NBCC") in  the LLC will be
redeemed for  $15.5 million;  (2) the  LLC  will be  merged into  Costilla  (the
"Merger") and an aggregate of 6,000,000 shares of Common Stock will be issued to
the  four members of  the LLC; (3) Costilla  will acquire all  of the issued and
outstanding stock of Valley and the assets of CSL for $0.7 million; and (4) $4.3
million in distributions will be made to the members of the LLC, $3.5 million of
which, in the case of Messrs. Liedtke, Grella and Musselman, will be provided to
such persons  for certain  estimated income  tax effects  of the  Merger.  These
transactions  are  referred  to  throughout this  Prospectus  as  the "Corporate
Reorganization." As a result of the Corporate Reorganization, Costilla will have
four wholly  owned subsidiaries:  (i) Costilla  Petroleum Corporation,  a  Texas
corporation  ("CPC"), which operates properties owned by Costilla and owns minor
interests in  the  same  properties;  (ii) Statewide  Minerals,  Inc.,  a  Texas
corporation ("Statewide"), which is engaged in the purchase of small royalty and
mineral interests; (iii) Valley, which owns several small gas gathering systems,
a  small  gas processing  plant,  certain salt  water  disposal systems  and gas
compressors;  and  (iv)  Costilla  Pipeline  Corporation,  a  Texas  corporation
("Pipeline") which owns a gas pipeline in Pennsylvania held for resale. CSL will
be  dissolved.  Costilla and  CPC  are the  sole  members of  two  Texas limited
liability  companies  through  which  the  Company's  Moldovan  operations   are
conducted.  Costilla also  owns a  45.0% interest  in a  Texas limited liability
company which owns  and operates  a gas  pipeline and  associated facilities  in
Louisiana.
    
 
    The  Company's executive  offices are  located at  400 West  Illinois, Suite
1000, Midland, Texas, 79701 and its telephone number is (915) 683-3092.
 
                             COMMON STOCK OFFERING
 
   
    Concurrent with the Notes Offering, the Company is offering 4,000,000 shares
of its Common Stock. The Notes Offering  and the Common Stock Offering are  each
conditioned upon the consummation of the other.
    
 
                                       16
<PAGE>
                                USE OF PROCEEDS
 
   
    The  net  proceeds of  the  Offerings are  estimated  to be  $151.5 million,
assuming an initial public offering price of  $15 per share in the Common  Stock
Offering ($159.8 million if the underwriters' over-allotment option with respect
to the Common Stock Offering is exercised). Approximately $125.8 million of such
proceeds,  including all the net proceeds of the Notes Offering, will be used to
repay all of  the existing  senior indebtedness  of the  Company (the  "Existing
Debt")  incurred in connection  with the 1996 Acquisition,  and to refinance its
previous credit facility. The Existing Debt matures in June 1999.  Approximately
$30.0  million of the Existing Debt currently  bears interest at 14.0% per annum
(increasing to 14.5%  on September  13, 1996)  and the  balance currently  bears
interest  at a rate selected by the Company  equal to a base rate (generally the
prime rate established by NationsBank, N.A.) plus 0.75% or LIBOR plus 3.0%.  See
"Description  of  Other Indebtedness."  In addition,  $20.5  million of  the net
proceeds will be  used to pay  certain amounts incurred  in connection with  the
Corporate  Reorganization, including $15.5 million  to redeem certain membership
interests of NBCC in the  LLC prior to the Merger,  $0.7 million to acquire  the
stock  of Valley and the assets of CSL  and $4.3 million in distributions to the
members of the  LLC, $3.5  million of  which, in  the case  of Messrs.  Liedtke,
Grella  and Musselman,  will be provided  to such persons  for certain estimated
federal income  tax  effects of  the  Merger. See  "Certain  Transactions."  The
remaining estimated net proceeds of $5.1 million will be used by the Company for
general  corporate purposes. Pending such uses,  the remaining net proceeds will
be invested in short-term, investment grade, interest-bearing securities.
    
 
    The following is  a description  of sources and  uses of  proceeds from  the
Offerings,  assuming the underwriters' over-allotment  option in connection with
the Common Stock Offering is not exercised (in millions):
 
   
<TABLE>
<S>                                                                  <C>
Sources:
  Notes Offering...................................................  $   100.0
  Common Stock Offering............................................       60.0
                                                                     ---------
                                                                     $   160.0
                                                                     ---------
                                                                     ---------
Uses:
  Refinance Existing Debt..........................................  $   125.8
  Redeem membership interests......................................       15.5
  Distributions to individual members to pay estimated income tax
   liability of such members.......................................        3.5
  Pro rata distribution to remaining member........................        0.8
  Purchase of stock of Valley and assets of CSL....................        0.7
  Working capital..................................................        5.1
  Estimated fees, commissions, underwriting discounts and expenses
   related to the Offerings........................................        8.6
                                                                     ---------
                                                                     $   160.0
                                                                     ---------
                                                                     ---------
</TABLE>
    
 
                                       17
<PAGE>
                                 CAPITALIZATION
 
   
    The following table sets forth  the unaudited capitalization of the  Company
as  of June 30,  1996, on an  historical basis and  on a pro  forma basis giving
effect to the Corporate Reorganization and the Offerings and the application  of
the  net proceeds therefrom, as if such  transactions had been consummated as of
June 30, 1996, assuming an  initial offering price for  the Common Stock in  the
Common  Stock Offering of $15  per share. The following  table should be read in
conjunction with the Consolidated Financial Statements of the LLC, the unaudited
Pro Forma  Condensed Financial  Statements,  the related  notes, and  the  other
information  contained elsewhere  in this Prospectus,  including the information
set forth in "Management's  Discussion and Analysis  of Financial Condition  and
Results  of  Operations." For  further information  regarding  the terms  of the
long-term debt  reflected in  the  following table,  see "Description  of  Other
Indebtedness"  and Note  7 and  Note 12 of  the Notes  to Consolidated Financial
Statements.
    
 
   
<TABLE>
<CAPTION>
                                                                                               JUNE 30, 1996
                                                                                          ------------------------
                                                                                          HISTORICAL    PRO FORMA
                                                                                          -----------  -----------
                                                                                               (IN THOUSANDS)
<S>                                                                                       <C>          <C>
Long-term debt:
  Existing debt.........................................................................  $   122,365  $       365
  Credit Facility.......................................................................           --           --
     % Senior Subordinated Notes due 2006...............................................           --      100,000
                                                                                          -----------  -----------
Total long-term debt....................................................................      122,365      100,365
                                                                                          -----------  -----------
Redeemable members' capital.............................................................       13,557           --
                                                                                          -----------  -----------
Members' capital and stockholders' equity:
  Members' capital......................................................................      (11,712)          --
  Preferred stock, $.10 par value (3,000,000 shares authorized; no shares issued or
   outstanding).........................................................................           --           --
  Common Stock, $.10 par value (20,000,000 shares authorized; no shares outstanding
   actual, 10,000,000 shares outstanding pro forma).....................................           --        1,000
  Paid-in capital.......................................................................           --       34,232
                                                                                          -----------  -----------
Total members' capital and stockholders' equity.........................................      (11,712)      35,232
                                                                                          -----------  -----------
Total capitalization....................................................................  $   124,210  $   135,597
                                                                                          -----------  -----------
                                                                                          -----------  -----------
</TABLE>
    
 
                                       18
<PAGE>
                    PRO FORMA CONDENSED FINANCIAL STATEMENTS
 
   
    The  unaudited Pro Forma Condensed Financial  Statements of the Company have
been prepared to give effect to  the 1995 Acquisition and the 1996  Acquisition,
the  Corporate  Reorganization, and  the Offerings  and  the application  of the
estimated net proceeds  therefrom as  if such  transactions (to  the extent  not
already  reflected) had  taken place on  June 30,  1996 for purposes  of the Pro
Forma Condensed Balance  Sheet and  as if the  transactions had  taken place  on
January  1,  1995  for  purposes  of  the  Pro  Forma  Condensed  Statements  of
Operations. The Pro Forma Condensed Financial Statements of the Company are  not
necessarily  indicative of  the results for  the periods presented  had the 1995
Acquisition and  the 1996  Acquisition, the  Corporate Reorganization,  and  the
Offerings  and the  application of  the estimated  net proceeds  therefrom taken
place on January  1, 1995. In  addition, future results  may vary  significantly
from  the results  reflected in the  accompanying Pro  Forma Condensed Financial
Statements because of normal production declines, changes in product prices, and
the success  of  future  exploration and  development  activities,  among  other
factors.  This information should  be read in  conjunction with the Consolidated
Financial Statements  of  Costilla  Energy, L.L.C.  and  subsidiaries,  and  the
Statements  of  Revenues  and  Direct Operating  Expenses  with  respect  to the
properties acquired  in  the 1995  Acquisition  and the  1996  Acquisition,  all
included elsewhere herein.
    
 
                                       19
<PAGE>
                             COSTILLA ENERGY, INC.
 
                 PRO FORMA CONDENSED BALANCE SHEET -- UNAUDITED
 
   
                                 JUNE 30, 1996
    
 
                                 (IN THOUSANDS)
   
<TABLE>
<CAPTION>
                                                                                                       PRO FORMA
                                                                                         PRO FORMA     COSTILLA
                                                                           COSTILLA       OFFERING      ENERGY,
                                ASSETS                                      L.L.C.      ADJUSTMENTS      INC.
- -----------------------------------------------------------------------  -------------  ------------  -----------
<S>                                                                      <C>            <C>           <C>
Current assets:
  Cash and cash equivalents............................................    $   1,164    $     (700)(1)  $  10,655
                                                                                           151,450(3)
                                                                                          (141,259)(4)
  Accounts receivable..................................................        8,785                       8,785
  Prepaid and other current assets.....................................        2,629                       2,629
                                                                         -------------                -----------
      Total current assets.............................................       12,578                      22,069
Oil and gas properties, using the successful efforts method of
 accounting:
  Proved properties....................................................      126,809                     125,809
  Unproved properties..................................................        4,615                       4,615
  Accumulated depreciation, depletion and amortization.................      (13,933)                    (13,933)
                                                                         -------------                -----------
Other property and equipment, net......................................        1,640           700(1)      2,340
Deferred charges (Note 2)..............................................        2,654         3,850(3)      3,850
                                                                                            (2,654)(4)
Note receivable -- affiliate...........................................          684                         684
                                                                         -------------                -----------
                                                                           $ 135,047                   $ 146,434
                                                                         -------------                -----------
                                                                         -------------                -----------
 
<CAPTION>
          LIABILITIES, REDEEMABLE MEMBERS' CAPITAL AND EQUITY
- -----------------------------------------------------------------------
<S>                                                                      <C>            <C>           <C>
Current liabilities:
  Current maturities of long-term debt.................................    $      98                   $      98
  Trade accounts payable...............................................        4,587                       4,587
  Undistributed revenue................................................        1,524                       1,524
  Other current liabilities............................................        2,103                       2,103
                                                                         -------------                -----------
      Total current liabilities........................................        8,312                       8,312
Long-term debt, less current maturities................................      122,267       100,000(3)    100,267
                                                                                          (122,000)(4)
Deferred income........................................................        2,623                       2,623
                                                                         -------------                -----------
      Total liabilities................................................      133,202                     111,202
Redeemable members' capital............................................       13,557       (13,557)(4)         --
Members' capital and stockholders' equity:
  Members' capital.....................................................      (11,712)       11,712(2)         --
  Preferred stock, $.10 par value (3,000,000 shares authorized; no
   shares outstanding).................................................           --                          --
  Common Stock, $.10 par value (20,000,000 shares authorized; no shares
   outstanding historical, 10,000,000 shares outstanding pro forma)....           --         1,000(3)      1,000
  Paid-in capital......................................................           --        (2,654)(4)     34,232
                                                                                            (1,443)(4)
                                                                                            (4,259)(4)
                                                                                            54,300(3)
                                                                                           (11,712)(2)
                                                                         -------------                -----------
  Total members' capital and stockholders' equity......................      (11,712)                     35,232
                                                                         -------------                -----------
                                                                           $ 135,047                   $ 146,434
                                                                         -------------                -----------
                                                                         -------------                -----------
</TABLE>
    
 
 See accompanying notes to unaudited pro forma condensed financial statements.
 
                                       20
<PAGE>
                             COSTILLA ENERGY, INC.
 
            PRO FORMA CONDENSED STATEMENT OF OPERATIONS -- UNAUDITED
 
                          YEAR ENDED DECEMBER 31, 1995
 
                     (IN THOUSANDS, EXCEPT PER SHARE DATA)
   
<TABLE>
<CAPTION>
                                                                                                  PRE OFFERING    PRO FORMA
                                            COSTILLA        1995         1996        PRO FORMA      COSTILLA       OFFERING
                                             L.L.C.      ACQUISITION  ACQUISITION   ADJUSTMENTS      L.L.C.      ADJUSTMENTS
                                          -------------  -----------  -----------  -------------  -------------  ------------
<S>                                       <C>            <C>          <C>          <C>            <C>            <C>
Revenues................................    $  21,816     $  10,930    $  19,891                    $  52,637
                                          -------------  -----------  -----------                 -------------
Expenses:
  Oil and gas production................       10,355         5,473       11,409    $    (300)(1)      26,937
  General and administrative............        3,571            --           --         (172)(1)       4,850
                                                                                        1,451(5)
  Exploration and abandonments..........        1,650           109        1,002                        2,761
  Depreciation, depletion and
   amortization.........................        5,958            --           --          100(1)       14,176
                                                                                        8,118(6)
  Interest..............................        4,591            --           --       10,046(7)       14,637    $   3,002(8)
  Other.................................            2            --           --                            2
                                          -------------  -----------  -----------                 -------------
                                               26,127         5,582       12,411                       63,363
                                          -------------  -----------  -----------                 -------------
Net income (loss) before federal income
 taxes..................................       (4,311)        5,348        7,480                      (10,726)
Provision for federal income taxes......            3            --           --                            3
                                          -------------  -----------  -----------                 -------------
Net income (loss).......................    $  (4,314)    $   5,348    $   7,480                    $ (10,729)
                                          -------------  -----------  -----------                 -------------
                                          -------------  -----------  -----------                 -------------
Net loss per share......................
 
<CAPTION>
                                           PRO FORMA
                                           COSTILLA
                                            ENERGY,
                                             INC.
                                          -----------
<S>                                       <C>
Revenues................................   $  52,637
                                          -----------
Expenses:
  Oil and gas production................      26,937
  General and administrative............       4,850
 
  Exploration and abandonments..........       2,761
  Depreciation, depletion and
   amortization.........................      14,176
 
  Interest..............................      11,635
  Other.................................           2
                                          -----------
                                              60,361
                                          -----------
Net income (loss) before federal income
 taxes..................................      (7,724)
Provision for federal income taxes......           3
                                          -----------
Net income (loss).......................   $  (7,727)
                                          -----------
                                          -----------
Net loss per share......................   $   (0.78)
                                          -----------
                                          -----------
</TABLE>
    
 
 See accompanying notes to unaudited pro forma condensed financial statements.
 
                                       21
<PAGE>
                             COSTILLA ENERGY, INC.
 
            PRO FORMA CONDENSED STATEMENT OF OPERATIONS -- UNAUDITED
 
   
                         SIX MONTHS ENDED JUNE 30, 1996
    
 
                     (IN THOUSANDS, EXCEPT PER SHARE DATA)
 
   
<TABLE>
<CAPTION>
                                                                                                                     PRO FORMA
                                                                                       PRE OFFERING    PRO FORMA     COSTILLA
                                             COSTILLA        1996        PRO FORMA       COSTILLA       OFFERING      ENERGY,
                                              L.L.C.      ACQUISITION   ADJUSTMENTS       L.L.C.      ADJUSTMENTS      INC.
                                           -------------  -----------  --------------  -------------  ------------  -----------
<S>                                        <C>            <C>          <C>             <C>            <C>           <C>
Revenues.................................    $  19,525     $   9,223                     $  28,748                   $  28,748
Expenses:
  Oil and gas production.................        8,278         5,167    $    (150)(1)       13,295                      13,295
  General and administrative.............        2,809                        (86)(1)        3,010                       3,010
                                                                              287(5)
  Exploration and abandonments...........          308           247                           555                         555
  Depreciation, depletion and
   amortization..........................        4,620                         50(1)         6,981                       6,981
                                                                            2,311(6)
  Interest...............................        4,156                      2,832(7)         6,988     $  (1,171)(8)     5,817
                                           -------------  -----------                  -------------                -----------
                                                20,171         5,414                        30,829                      29,658
                                           -------------  -----------                  -------------                -----------
Net income (loss) before federal income
 taxes...................................         (646)        3,809                        (2,081)                       (910)
                                           -------------  -----------                  -------------                -----------
Net income (loss)........................    $    (646)    $   3,809                     $  (2,081)                  $    (910)
                                           -------------  -----------                  -------------                -----------
                                           -------------  -----------                  -------------                -----------
Net income (loss) per share..............                                                                            $   (0.09)
                                                                                                                    -----------
                                                                                                                    -----------
</TABLE>
    
 
 See accompanying notes to unaudited pro forma condensed financial statements.
 
                                       22
<PAGE>
                             COSTILLA ENERGY, INC.
          NOTES TO UNAUDITED PRO FORMA CONDENSED FINANCIAL STATEMENTS
 
NOTE 1. -- BASIS OF PRESENTATION
   
    The  Pro  Forma  Condensed Financial  Statements  of the  Company  have been
prepared to give effect  to the 1995 Acquisition  and the 1996 Acquisition,  the
Corporate  Reorganization and the Offerings and the application of estimated net
proceeds therefrom, as if such transactions had taken place on June 30, 1996 for
purposes of the  Pro Forma Condensed  Balance Sheet (with  the exception of  the
1995 Acquisition which was previously reflected in the balance sheet of Costilla
Energy,  L.L.C.), and as if each of  the transactions had taken place on January
1, 1995 for purposes  of the Pro Forma  Condensed Statements of Operations.  The
1995 Acquisition and 1996 Acquisition are accounted for by the purchase method.
    
 
   
        Costilla  L.L.C.  -- Represents  the  consolidated balance  sheet of
    Costilla Energy, L.L.C.  and subsidiaries as  of June 30,  1996 and  the
    related  consolidated  statements  of  operations  for  the  year  ended
    December 31, 1995 and the six months ended June 30, 1996.
    
 
        1995 Acquisition  -- Represents  the revenues  and direct  operating
    expenses  of the  properties acquired  in the  1995 Acquisition  for the
    period from  January  1,  1995  to  June 12,  1995  (date  of  the  1995
    Acquisition).
 
   
        1996  Acquisition --  Represents the  revenues and  direct operating
    expenses of  the properties  acquired in  the 1996  Acquisition for  the
    period  from  January  1,  1995  to June  14,  1996  (date  of  the 1996
    Acquisition).
    
 
NOTE 2. -- PRO FORMA ENTRIES
 
   
    (1) To record the acquisition of Valley Gathering Company and CSL Management
Corporation from certain members  of Costilla Energy, L.L.C.  and to record  the
related  additional depreciation and amortization, and  reduction in oil and gas
production and general and administrative expenses.
    
 
   
    (2) To  reflect  the  Corporate Reorganization  including  the  transfer  of
members' capital to stockholders' equity.
    
 
   
    (3)  To  reflect the  issuance of  4,000,000  shares of  Common Stock  at an
estimated price of $15.00 per share  for estimated proceeds of $55,300,000,  net
of estimated expenses of the Common Stock Offering, and issuance of the Notes at
$100,000,000;  and  to  reflect payment  of  related debt  issuance  expenses of
$3,850,000.
    
 
   
    (4) To  record the  repayment of  the  Existing Debt  and the  write-off  of
related  debt issuance costs,  the distribution of cash  to certain members, and
the repurchase of redeemable members capital for approximately $15,000,000  from
proceeds of the Offerings.
    
 
   
    The redemption amount is composed of the following:
    
 
   
<TABLE>
<S>                                                             <C>
Redeemable members' interest subject to preferred return......  $11,000,000
Redeemable members' interest not subject to preferred
 return.......................................................    1,500,000
Accrued 15% preferred return including associated 10%
 redemption premium...........................................    2,500,000
                                                                -----------
                                                                $15,000,000
                                                                -----------
                                                                -----------
</TABLE>
    
 
   
    (5)  Estimated incremental general and  administrative expenses necessary to
administer the  properties  acquired  in  the 1995  and  1996  acquisitions  and
increased  public reporting and administration costs include salary and benefits
for one executive level employee  and revised compensation arrangements for  the
remaining  executives, approximately 29 additional administrative personnel (the
majority of  which were  added prior  to December  31, 1995),  directors'  fees,
insurance coverage and estimated costs to administer shareholder communications.
    
 
                                       23
<PAGE>
                             COSTILLA ENERGY, INC.
    NOTES TO UNAUDITED PRO FORMA CONDENSED FINANCIAL STATEMENTS (CONTINUED)
 
   
NOTE 2. -- PRO FORMA ENTRIES (CONTINUED)
    
   
    (6)  To record  estimated incremental  depletion expense  for the properties
acquired in the  1995 Acquisition  from January 1,  1995 through  June 12,  1995
(date  of the  1995 Acquisition)  and for  the properties  acquired in  the 1996
Acquisition from  January  1, 1995  through  June 14,  1996  (date of  the  1996
Acquisition).
    
 
   
    (7)  To adjust  interest expense  to reflect  additional borrowings  for the
properties acquired in  the 1995 Acquisition  from January 1,  1995 to June  12,
1995  (date of the 1995 Acquisition) and for the properties acquired in the 1996
Acquisition  from  January  1,  1995  to  June  14,  1996  (date  of  the   1996
Acquisition).  The adjustment also reflects adjusted interest expense due to the
Existing Debt.  Also included  is the  amortization of  estimated debt  issuance
costs of $2,728,000 over a three-year period.
    
 
   
    Incremental interest expense includes the following components:
    
 
   
<TABLE>
<CAPTION>
                                                             YEAR ENDED      SIX MONTHS ENDED
                                                          DECEMBER 31, 1995    JUNE 30, 1996
                                                          -----------------  -----------------
<S>                                                       <C>                <C>
Additional interest on borrowings associated with the
 1995 Acquisition for the period of January 1 to June
 12, 1995 (Average rate 10.0%)..........................     $     2,350         $      --
Additional interest on borrowings for the 1996
 Acquisition through June 14, 1996 (including Tranche B
 interest ranging from 14% to 16.5%)....................           6,750             2,300
Adjustment of average interest rate on previously
 existing debt and amortization of loan fees............             946               532
                                                                --------           -------
                                                             $    10,046         $   2,832
                                                                --------           -------
                                                                --------           -------
</TABLE>
    
 
   
    (8)  To adjust interest expense  to reflect issuance of  the Notes at 11.25%
plus the amortization of estimated debt  issuance costs over 10 years  ($385,000
annually).
    
 
NOTE 3. -- INCOME TAXES
   
    Upon  consummation of the  Corporate Reorganization, the  Company intends to
account for income taxes  pursuant to the  provisions of SFAS  109. At June  30,
1996,  the pro forma tax basis of  the Company's assets and liabilities exceeded
the pro forma book  basis by approximately $5,000,000.  The pro forma  temporary
differences  are primarily related to  the differences in book  and tax basis of
oil and gas properties due to the expensing of intangible development costs  for
tax  purposes and other income tax differences arising from the tax treatment of
oil and gas producing activities.
    
 
   
NOTE 4. -- NET LOSS PER SHARE
    
   
    Net loss per  share is calculated  based on the  pro forma weighted  average
shares  outstanding  during  the  respective  periods.  Weighted  average shares
reflect the pro forma issuance  of 1,080,008 shares of  Common Stock to NBCC  on
February 17, 1995 and the pro forma issuance of 4,919,992 shares of Common Stock
to  the remaining holders prior to January 1, 1995. In addition, the issuance of
4,000,000 shares in the Common Stock Offering is assumed to have taken place  on
January  1, 1995 and assumes that the Underwriters' over-allotment option is not
exercised.
    
 
NOTE 5. -- SUPPLEMENTAL OIL AND GAS RESERVE INFORMATION
   
    The estimates  of proved  oil and  gas reserves,  which are  located in  the
United  States, were prepared by  the Company as of  December 31, 1993, 1994 and
1995, and Williamson as of April 1, 1996.
    
 
                                       24
<PAGE>
                             COSTILLA ENERGY, INC.
    NOTES TO UNAUDITED PRO FORMA CONDENSED FINANCIAL STATEMENTS (CONTINUED)
 
NOTE 5. -- SUPPLEMENTAL OIL AND GAS RESERVE INFORMATION (CONTINUED)
   
Reserves were  estimated  in  accordance  with  guidelines  established  by  the
Securities and Exchange Commission and FASB which require that reserve estimates
be  prepared under existing economic and  operating conditions with no provision
for price and cost escalations, except by contractual arrangements. The  Company
has  presented the pro forma reserve estimates  utilizing an oil price of $17.79
per Bbl and a gas  price of $2.03 per  Mcf as of December  31, 1995, and an  oil
price  of $20.91 per Bbl and  a gas price of $2.02 per  Mcf as of April 1, 1996.
The pro forma information  assumes that both the  1995 Acquisition and the  1996
Acquisition took place on January 1, 1995.
    
 
OIL AND GAS PRODUCING ACTIVITIES
 
    Oil and gas reserve quantity estimates are subject to numerous uncertainties
inherent  in  the  estimation  of  quantities  of  proved  reserves  and  in the
projection  of  future  rates  of  production  and  the  timing  of  development
expenditures.  The accuracy of  such estimates is  a function of  the quality of
available data and  of engineering and  geological interpretation and  judgment.
Results  of subsequent drilling, testing and  production may cause either upward
or downward revision of previous  estimates. Further, the volumes considered  to
be  commercially  recoverable fluctuate  with  changes in  prices  and operating
costs. The Company  emphasizes that reserve  estimates are inherently  imprecise
and that estimates of new discoveries are more imprecise that those of currently
producing  oil and gas properties. Accordingly,  these estimates are expected to
change as additional information becomes available in the future.
 
   
<TABLE>
<CAPTION>
                                                                              OIL AND            GAS
                                                                        CONDENSATE (MBBLS)     (MMCF)
                                                                        -------------------  -----------
<S>                                                                     <C>                  <C>
Balance, January 1, 1995..............................................           17,990         115,281
  Revisions of previous estimates.....................................             (570)            425
  Extensions and discoveries..........................................              605           8,922
  Production..........................................................           (2,085)        (11,984)
                                                                                -------      -----------
Balance, December 31, 1995............................................           15,940         112,644
  Revisions of previous estimates.....................................              436           2,614
  Extensions and discoveries..........................................              592             296
  Production..........................................................             (492)         (2,634)
                                                                                -------      -----------
Balance, April 1, 1996................................................           16,476         112,920
                                                                                -------      -----------
                                                                                -------      -----------
Proved Developed Reserves:
  December 31, 1995...................................................           13,235          87,345
  April 1, 1996.......................................................           13,552          84,369
</TABLE>
    
 
STANDARDIZED MEASURE OF DISCOUNTED FUTURE NET CASH FLOWS RELATING TO PROVED OIL
AND GAS RESERVES
 
    The standardized measure of discounted future net cash flows is computed  by
applying  period-end prices of oil and  gas (with consideration of price changes
only to the extent provided by contractual arrangements) to the estimated future
production of proved oil  and gas reserves less  estimated future production  of
proved oil and gas reserves less estimated future expenditures (based on period-
end  costs) to be incurred in developing and producing the proved reserves, less
estimated future income tax expenses  (based on period-end statutory tax  rates,
with  consideration of  future tax rates  already legislated) to  be incurred on
pretax net cash flows  less tax basis of  properties and available credits,  and
assuming  continuation of existing economic conditions. The estimated future net
cash flows are  then discounted  using a  rate of 10%  per year  to reflect  the
estimated timing of the future cash flows.
 
    Discounted  future  cash  flow  estimates like  those  shown  below  are not
intended to represent  estimates of the  fair value of  oil and gas  properties.
Estimates of fair value should also consider
 
                                       25
<PAGE>
                             COSTILLA ENERGY, INC.
    NOTES TO UNAUDITED PRO FORMA CONDENSED FINANCIAL STATEMENTS (CONTINUED)
 
NOTE 5. -- SUPPLEMENTAL OIL AND GAS RESERVE INFORMATION (CONTINUED)
probable  reserves,  anticipated  future  oil and  gas  prices,  interest rates,
changes in development  and production  costs and risks  associated with  future
production.  Because of  these and  other considerations,  any estimate  of fair
value is necessarily subjective and imprecise.
 
   
<TABLE>
<CAPTION>
                                                                           DECEMBER 31,    MARCH 31,
                                                                               1995           1996
                                                                           ------------  --------------
                                                                                  (IN THOUSANDS)
<S>                                                                        <C>           <C>
Future cash flows........................................................   $  512,363    $    572,425
Future costs:
  Production.............................................................     (239,388)       (253,347)
  Development............................................................      (20,907)        (22,076)
                                                                           ------------  --------------
Future net cash flows before income taxes (a)............................      252,068         297,002
Future income taxes......................................................      (47,282)        (63,418)
                                                                           ------------  --------------
Future net cash flows....................................................      204,786         233,584
10% annual discount for estimated timing of cash flows...................      (64,152)        (76,359)
                                                                           ------------  --------------
Standardized measure of discounted net cash flows........................   $  140,634    $    157,225
                                                                           ------------  --------------
                                                                           ------------  --------------
</TABLE>
    
 
- ------------------------
   
(a) Present value of estimated future net cash flows, before income taxes  would
    be  $153,373  and $179,527  as  of December  31,  1995 and  March  31, 1996,
    respectively.
    
 
Changes in Standardized Measure of Discounted Future Net Cash Flows From Proved
Reserves:
 
<TABLE>
<CAPTION>
                                                                           YEAR ENDED    THREE MONTHS
                                                                          DECEMBER 31,  ENDED MARCH 31,
                                                                              1995           1996
                                                                          ------------  ---------------
                                                                                 (IN THOUSANDS)
<S>                                                                       <C>           <C>
Increase (decrease):
  Extensions and discoveries and improved recovery, net of future
   production and development costs.....................................   $    9,598     $     6,002
  Accretion of discount.................................................       14,147           3,516
  Net change in sales prices, net of production costs...................        2,992          20,807
  Changes in estimated future development costs.........................       (1,651)           (238)
  Revisions of quantity estimates.......................................       (2,392)          4,694
  Net change in income taxes............................................        1,633          (9,563)
  Sales, net of production costs........................................      (27,055)         (7,264)
  Changes of production rates (timing) and other........................        1,893          (1,363)
                                                                          ------------  ---------------
    Net increase (decrease).............................................         (835)         16,591
Standardized measure of discounted future net cash flows:
  Beginning of period...................................................      141,469         140,634
                                                                          ------------  ---------------
  End of period.........................................................   $  140,634     $   157,225
                                                                          ------------  ---------------
                                                                          ------------  ---------------
</TABLE>
 
                                       26
<PAGE>
                         SELECTED FINANCIAL INFORMATION
 
    The  following table sets forth selected  financial data of Costilla Energy,
L.L.C. See  "Management's Discussion  and Analysis  of Financial  Condition  and
Results of Operations." The historical information should be read in conjunction
with  the  Consolidated  Financial  Statements and  the  notes  thereto included
elsewhere in  this  Prospectus.  Costilla Energy,  L.L.C.  acquired  significant
producing  oil  and gas  properties in  certain of  the periods  presented which
affect the comparability of the historical financial and operating  information.
The  historical results are  not necessarily indicative  of the Company's future
operations or financial results.
 
   
<TABLE>
<CAPTION>
                                                                                                     SIX MONTHS ENDED
                                                           YEAR ENDED DECEMBER 31,                       JUNE 30,
                                            -----------------------------------------------------  --------------------
                                              1991       1992       1993       1994       1995       1995       1996
                                            ---------  ---------  ---------  ---------  ---------  ---------  ---------
                                                                   (IN THOUSANDS, EXCEPT RATIOS)
<S>                                         <C>        <C>        <C>        <C>        <C>        <C>        <C>
STATEMENT OF OPERATIONS DATA:
  Operating revenues......................  $   1,623  $   2,364  $   4,231  $   7,637  $  21,693  $   5,568  $  19,445
  Total revenues..........................      2,134      2,887      4,397      7,836     21,816      5,573     19,525
  Expenses:
    Oil and gas production................        769      1,340      1,688      2,351     10,355      2,413      8,278
    General and administrative............        354        388        952      1,184      3,571      1,008      2,809
    Exploration and abandonments..........        106          4        218        793      1,650      1,007        308
    Depreciation, depletion and
     amortization.........................        494        404        884      1,847      5,958      1,367      4,620
    Interest..............................        179        365        605      1,458      4,591      1,046      4,156
    Other.................................         --         --         --         --          2         --         --
                                            ---------  ---------  ---------  ---------  ---------  ---------  ---------
  Income (loss) before income taxes and
   extraordinary item.....................        232        386         50        203     (4,311)    (1,268)      (646)
  Net income (loss).......................        234        368         73        163     (4,314)    (1,268)    (2,286)
STATEMENT OF CASH FLOWS DATA:
  Net cash provided by (used in):
    Operating activities..................  $     276  $     140  $     322  $   1,527  $   6,366  $  (3,040) $    (122)
    Investing activities..................     (2,659)    (1,432)    (6,731)   (12,146)   (62,467)   (57,773)   (49,723)
    Financing activities..................      2,440      1,450      6,315     10,618     58,830     62,094     48,143
OTHER FINANCIAL DATA:
  Capital expenditures....................  $   3,092  $   3,720  $   6,862  $  11,868  $  62,220  $  57,773  $  49,723
  Distributions to members................         --         --        456        961         55         55         --
  Adjusted EBITDA (1).....................      1,011      1,159      1,757      4,301      7,888      2,152      8,438
  Adjusted EBITDA/interest expense (1)....        5.6x       3.2x       2.9x       2.9x       1.7x       2.1x       2.0x
  Ratio of earnings to fixed charges
   (2)....................................        1.3        1.5        1.0        1.1         --         --         --
BALANCE SHEET DATA (AS OF PERIOD END):
  Working capital.........................  $    (580) $     185  $   1,612  $   1,081  $   2,496         --  $   4,266
  Total assets............................      4,602      6,675     13,365     24,904     87,367         --    135,047
  Total debt..............................      2,870      5,304     12,006     23,613     71,494         --    122,365
  Redeemable members' capital.............         --         --         --         --     12,278         --     13,557
  Members' capital........................        504        434         51       (747)    (8,147)        --    (11,712)
</TABLE>
    
 
- ------------------------------
   
(1) Adjusted EBITDA  and the ratio  of Adjusted EBITDA  to interest expense  are
    presented  because of  their wide  acceptance as  financial indicators  of a
    company's ability to service or incur debt. Adjusted EBITDA (as used herein)
    is calculated by adding interest, income taxes, depreciation, depletion  and
    amortization,  exploration  and  abandonment  costs  and  extraordinary loss
    resulting from extinguishment  of debt to  net income (loss).  The ratio  of
    Adjusted  EBITDA  to interest  expense  is calculated  by  dividing Adjusted
    EBITDA  by  interest.  Interest   includes  interest  expense  accrual   and
    amortization  of deferred financing costs. Adjusted  EBITDA and the ratio of
    Adjusted EBITDA to interest expense should not be considered as alternatives
    to earnings (loss), or  operating earnings (loss),  as defined by  generally
    accepted  accounting principles,  as indicators  of the  Company's financial
    performance or to cash flow as a measure of liquidity.
    
 
   
(2) For  purposes  of  calculating  the ratio  of  earnings  to  fixed  charges,
    "earnings"  are net income  (loss) before extraordinary  loss resulting from
    extinguishment of debt, plus income  taxes and fixed charges. Fixed  charges
    are   comprised  of  interest  on  indebtedness,  amortization  of  deferred
    financing costs, and that portion of operating lease expense which is deemed
    to be representative of  an interest factor.  Earnings were insufficient  to
    cover   fixed  charges  by  $4,311,000,  $1,268,000  and  $646,000  for  the
    historical periods ended December 31, 1995, June 30, 1995 and June 30, 1996,
    respectively.
    
 
                                       27
<PAGE>
          MANAGEMENT'S DISCUSSION AND ANALYSIS OF FINANCIAL CONDITION
                           AND RESULTS OF OPERATIONS
 
GENERAL
 
    Costilla  is  an  independent  energy company  engaged  in  the exploration,
acquisition and development of oil and gas properties. The Company's predecessor
began operating  in 1988  and through  mid-1995 had  grown primarily  through  a
series  of small acquisitions of oil and  gas properties and the exploitation of
those properties. In June 1995, Costilla consummated the 1995 Acquisition for  a
purchase  price  of approximately  $46.6  million, and  in  June 1996,  the 1996
Acquisition was consummated for a purchase price of approximately $42.5 million.
 
    To date, the Company has achieved its high rate of growth primarily  through
acquisitions.  This has impacted  its reported financial results  in a number of
ways. Properties sold by others  frequently have not received focused  attention
prior  to sale. After  acquisition, certain of  these properties are  in need of
maintenance,  workovers,   recompletions  and   other  remedial   activity   not
constituting  capital expenditures, which substantially increase lease operating
expenses. The increased production and revenue resulting from these expenditures
is predominately realized  in periods subsequent  to the period  of expense.  In
addition,  the rapid growth of the Company has required it to develop operating,
accounting and administrative personnel compatible with its increased size.  The
Company  believes it has  now achieved a  sufficient size to  expand its reserve
base without a corresponding increase in its general and administrative expense.
The Company also believes it now has a sufficient inventory of prospects and the
professional staff necessary to  follow a more  balanced program of  exploration
and exploitation activities to complement its acquisition efforts.
 
    Costilla's  strategy is to increase its oil and gas reserves, production and
cash flow  from operations  through  a two-pronged  approach which  combines  an
active  exploration  program with  the  acquisition and  exploitation  of proved
reserves. In  addition,  Costilla  continues  to  evaluate  the  acquisition  of
undeveloped   acreage  for  its  exploration   efforts.  Costilla  has  in-house
exploration expertise  using 3-D  seismic technology  to identify  new  drilling
opportunities as well as for the exploitation of acquired properties.
 
   
    Costilla  has  shown a  significant increase  in its  oil and  gas reserves,
production and Adjusted EBITDA, especially due  to the 1995 Acquisition and  the
1996  Acquisition.  The following  table sets  forth  certain operating  data of
Costilla for the periods presented:
    
 
   
<TABLE>
<CAPTION>
                                                                                         SIX MONTHS ENDED
                                                          YEAR ENDED DECEMBER 31,            JUNE 30,
                                                      -------------------------------  --------------------
                                                        1993       1994       1995       1995       1996
                                                      ---------  ---------  ---------  ---------  ---------
<S>                                                   <C>        <C>        <C>        <C>        <C>
OIL AND GAS PRODUCTION:
  Oil (MBbls).......................................        158        330        950        233        709
  Gas (Mmcf)........................................        865      1,600      4,806      1,233      3,504
  MBOE..............................................        302        597      1,751        438      1,293
AVERAGE SALES PRICES (1):
  Oil (per Bbl).....................................  $   16.93  $   15.25  $   15.53  $   16.12  $   18.99
  Gas (per Mcf).....................................       1.82       1.63       1.45       1.47       1.91
PRODUCTION COST (2):
  Per BOE (3).......................................  $    5.59  $    3.94  $    5.91  $    5.51  $    6.40
  Per dollar of sales...............................       0.40       0.31       0.48       0.43       0.43
DEPRECIATION, DEPLETION AND AMORTIZATION:
  Per BOE...........................................  $    2.93  $    3.09  $    3.40  $    3.12  $    3.57
  Per dollar of sales...............................       0.21       0.24       0.27       0.25       0.25
</TABLE>
    
 
- ------------------------------
(1)  Before deduction of production taxes and net of hedging results.
 
(2)  Excludes depreciation, depletion and amortization. Production cost includes
     lease  operating  expenses  and  production   and  ad  valorem  taxes,   if
     applicable.
 
   
(3)  Production costs per BOE in 1995 and for the six months ended June 30, 1996
     were  unusually high as a result  of relatively high workover expenses with
     respect to  properties  acquired in  the  1995 Acquisition  which  did  not
     produce   related   production   improvement   until   subsequent  periods.
     Additionally, the Company's 1995  production costs were adversely  affected
     by  expenses  incurred in  connection with  plugging  wells to  comply with
     applicable regulatory requirements.
    
 
                                       28
<PAGE>
    Costilla uses the successful  efforts method of accounting  for its oil  and
gas activities. Costs to acquire mineral interests in oil and gas properties, to
drill  and equip exploratory wells that result  in proved reserves, and to drill
and equip development wells  are capitalized. Costs  to drill exploratory  wells
that  do  not result  in proved  reserves,  geological, geophysical  and seismic
costs, and costs  of carrying  and retaining unproved  properties are  expensed.
Capitalized  costs  of  producing  oil  and  gas  properties,  after considering
estimated dismantlement and abandonment costs and estimated salvage values,  are
depreciated  and depleted using the  unit-of-production method. Unproved oil and
gas properties that are individually  significant are periodically reviewed  for
impairment  of value,  and a  loss is  recognized at  the time  of impairment by
providing an impairment allowance. Other unproved properties are amortized based
on the Company's experience of successful drilling and average holding period.
 
   
    The Company utilizes option contracts to  hedge the effect of price  changes
on  a portion of  its future oil  and gas production.  Premiums paid and amounts
receivable under the option contracts are  amortized and accrued to oil and  gas
sales,  respectively. If market prices of oil and gas exceed the strike price of
put options,  the  options  will expire  unexercised,  therefore,  reducing  the
effective  price  received for  oil and  gas sales  by the  cost of  the related
option. Conversely, if  market prices of  oil and gas  decline below the  strike
price  of put options, the options  will be exercised, therefore, increasing the
effective price received for oil and gas sale by the proceeds received from  the
related  option. The  net effect of  the Company's  commodity hedging activities
reduced  oil  and  gas  revenues  by  $9,000,  $80,000,  $80,000  and  $854,000,
respectively, for the years ended December 31, 1994 and 1995, and the six months
ended  June 30, 1995 and 1996 and increased  oil and gas revenues by $71,000 for
the year  ended  December  31,  1993.  See  "Business  and  Properties  --  Risk
Management."
    
 
   
    The  Company utilizes interest rate swap  agreements to reduce the potential
impact of  increases in  interest rates  on floating-rate,  long term  debt.  If
market  rates of interest experienced during  the applicable swap term are below
the rate  of interest  effectively fixed  by  the swap  agreement, the  rate  of
interest  incurred by  the Company  will exceed  the rate  that would  have been
experienced under the Credit Agreement. The net effect of the Company's interest
rate hedging activities increased interest expense by $8,000 for the year  ended
December 31, 1995 and $359,000 for the six months ended June 30, 1996.
    
 
    The  Company's  predecessors  were classified  as  partnerships  for federal
income tax purposes. Therefore, no income taxes were paid or provided for by the
Company prior to the  Offerings. Future tax amounts,  if any, will be  dependent
upon  several factors,  including but  not limited  to the  Company's results of
operations.
 
RESULTS OF OPERATIONS
 
   
  SIX MONTHS ENDED JUNE 30, 1996 COMPARED TO SIX MONTHS ENDED JUNE 30, 1995
    
 
   
    The Company's total oil and gas revenues  for the six months ended June  30,
1996  were  $19,445,000, representing  an  increase of  $13,877,000  (249%) over
revenues of $5,568,000  for the  comparable period  in 1995.  This increase  was
primarily  due  to  the  1995  Acquisition  which  accounted  for  approximately
$12,300,000 of the revenue increase. Prior  to accounting for the impact of  the
1995  Acquisition  and the  1996 Acquisition,  the Company's  total oil  and gas
revenues for the six months ended June 30, 1996 increased by $658,000 (12%) over
the same period in 1995.
    
 
   
    Oil and gas production  was 1,293 MBOE  in the 1996  period compared to  438
MBOE  in the 1995 period.  Of the 855 MBOE  increase, approximately 800 MBOE was
due to the  properties acquired in  the 1995 Acquisition.  The remainder of  the
increase  was due  to a  combination of  successful drilling  activities and the
enhancement of existing production.
    
 
   
    Interest and other revenues were $40,000  for the six months ended June  30,
1996  compared  to $5,000  for the  comparable period  in 1995,  representing an
increase of $35,000, which was primarily
    
 
                                       29
<PAGE>
   
comprised of an increase in interest income of $33,000 in 1996 due to  increased
funds  earning interest. Also in the 1996  period, the Company realized gains of
$40,000 on various transactions for which there were no comparable  transactions
for the six months ended June 30, 1995.
    
 
   
    Oil  and gas production costs in the  1996 period were $8,278,000 ($6.40 per
BOE), compared to $2,413,000 in 1995  ($5.51 per BOE), representing an  increase
of  $5,865,000 (243%),  due principally  to the 1995  Acquisition. On  a per BOE
basis, production  costs increased  $0.89  due primarily  to costs  incurred  to
exploit  the properties acquired  in the 1995 Acquisition  which did not produce
related production improvement for the full period.
    
 
   
    General and administrative expense  for the six months  ended June 30,  1996
was   $2,809,000,  representing  an  increase  of  $1,801,000  (179%)  from  the
comparable period in  1995 of $1,008,000.  The increase is  primarily due to  an
increase  in personnel and related costs  necessary to accommodate the increased
activities of the Company due to the 1995 Acquisition and in anticipation of the
1996 Acquisition.
    
 
   
    Exploration and abandonment expense decreased to $308,000 in the 1996 period
compared to $1,007,000 in  1995. The Company incurred  $80,000 of seismic  costs
for the six months ended June 30, 1996, compared to $467,000 which were incurred
for  the comparable period  in 1995. Dry  hole costs decreased  from $540,000 to
$228,000 for the comparable periods in 1995 and 1996, respectively.
    
 
   
    Depreciation, depletion and  amortization expense  for the  1996 period  was
$4,620,000  compared to $1,367,000 for the 1995 period, representing an increase
of $3,253,000 (238%). During 1996,  depreciation, depletion and amortization  on
oil and gas production was provided at an average rate of $3.57 per BOE compared
to  $3.12  per  BOE  for  1995.  The increase  was  due  primarily  to  the 1995
Acquisition.
    
 
   
    Interest expense was $4,156,000 in  the 1996 period, compared to  $1,046,000
for   the  comparable  period  in  1995.  The  $3,110,000  (297%)  increase  was
attributable primarily to  increased levels of  debt which the  Company used  to
finance the 1995 Acquisition. The average amounts of applicable interest-bearing
debt  for  the  comparable  periods  in  1996  and  1995  were  $77,646,000  and
$25,145,000, respectively.
    
 
  YEAR ENDED DECEMBER 31, 1995 COMPARED TO YEAR ENDED DECEMBER 31, 1994
 
    The Company's  total  oil  and  gas  revenues  for  1995  were  $21,693,000,
representing  an increase of  $14,056,000 (184%) over  revenues of $7,637,000 in
1994. This increase was  primarily due to the  1995 Acquisition which  accounted
for approximately $12,032,000 of the revenue increase.
 
    Oil  and gas production was 1,751 MBOE in  1995 and 597 MBOE in 1994. Of the
1,154 MBOE increase, 1,099 MBOE was due  to the properties acquired in the  1995
Acquisition.
 
    Interest  and other  revenues were $123,000  in 1995 compared  to $87,000 in
1994, representing  an increase  of $36,000  (41%), which  was comprised  of  an
increase  in interest income  of $59,000 in  1995 due to  an increased amount of
funds earning  interest, partially  offset  by a  decrease  of other  income  of
$23,000. In 1994, the Company realized a gain of $112,000 on the sale of various
properties for which there were no comparable gains in 1995.
 
   
    Oil  and  gas production  costs in  1995 were  $10,355,000 ($5.91  per BOE),
compared to $2,351,000  in 1994  ($3.94 per  BOE), representing  an increase  of
$8,004,000  (340%).  The major  portion  of the  increase  was due  to increased
production associated with the 1995  Acquisition. In addition, certain  acquired
properties  required remedial workovers and other activity immediately following
acquisition resulting  in  unusual  operating costs  of  approximately  $600,000
during  1995.  In  addition,  $1,605,000 of  operating  costs  were  incurred in
connection with properties acquired in late 1994.
    
 
                                       30
<PAGE>
    General and administrative expense for 1995 was $3,571,000, representing  an
increase  of $2,387,000 (202%) from 1994  expense of $1,184,000. The increase is
primarily due  to  an increase  in  personnel  and related  costs  necessary  to
accommodate the increased activities of the Company due to the 1995 Acquisition.
 
    Exploration and abandonment expense increased to $1,650,000 in 1995 compared
to  $793,000 in 1994. The increase  of $857,000 (108%) was comprised principally
of $790,000 of seismic costs.
 
   
    Depreciation, depletion  and amortization  expense for  1995 was  $5,958,000
compared  to $1,847,000 for 1994, representing an increase of $4,111,000 (233%).
During 1995, depreciation, depletion and amortization on oil and gas  production
was  provided at an average rate of $3.40  per BOE compared to $3.09 per BOE for
1994. The increase was due primarily to the 1995 Acquisition.
    
 
   
    Interest expense was $4,591,000 in 1995 compared to $1,458,000 in 1994.  The
$3,133,000  (215%) increase was  attributable to increased  levels of debt which
the Company  used  to finance  the  1995  Acquisition. The  average  amounts  of
applicable   interest-bearing  debt  in  1995  and  1994  were  $49,972,000  and
$17,632,000, respectively.
    
 
  YEAR ENDED DECEMBER 31, 1994 COMPARED TO YEAR ENDED DECEMBER 31, 1993
 
    The  Company's  total  oil  and  gas  revenues  for  1994  were  $7,637,000,
representing  an increase  of $3,406,000  (81%) over  revenues of  $4,231,000 in
1993.  The  primary  reason  for  the  increase  in  revenues  was  due  to  two
acquisitions  of properties in 1994,  one of which occurred  in January 1994 and
the other in October 1994.
 
    Oil and  gas production  was 597  MBOE in  1994 and  302 MBOE  in 1993.  The
increase  in production of  295 MBOE was principally  due to properties acquired
during 1994.
 
    Interest and other  revenues were  $87,000 in  1994 compared  to $56,000  in
1993. The increase of $31,000 was comprised of an increase in interest income of
$26,000  in 1994,  due to  increased funds  earning interest,  and an additional
$5,000 in other income.
 
    Oil and  gas production  costs  in 1994  were  $2,351,000 ($3.94  per  BOE),
compared  to $1,688,000  in 1993  ($5.59 per  BOE), representing  an increase of
$663,000. The  increase in  production costs  is primarily  attributable to  two
acquisitions in 1994.
 
    In  1994, general and administrative expense was $1,184,000, representing an
increase of $232,000 (24%) from 1993 expense of $952,000. The increase is due to
an increase in  personnel and costs  related primarily to  acquisitions made  in
1994.
 
    Exploration  and abandonment expense increased  to $793,000 in 1994 compared
to $218,000 in 1993. The increase of  $575,000 (264%) was due to an increase  in
non-productive wells drilled in 1994 compared to 1993.
 
    Depreciation,  depletion and  amortization expense  for 1994  was $1,847,000
compared to  $884,000 for  1993, representing  an increase  of $963,000  (109%),
primarily  due to increased production. During 1994, depreciation, depletion and
amortization expense on oil and gas  production was provided at an average  rate
of  $3.09 per BOE  compared to $2.93 per  BOE for 1993. The  increase was due to
increased  drilling  and   development,  and  the   acquisition  of   additional
properties.
 
    Interest  expense was $1,458,000  in 1994 compared to  $605,000 in 1993. The
$853,000 increase was attributable to increased debt levels related primarily to
the Company's acquisition  of additional  oil and  gas properties  in 1994.  The
average  amount  of  applicable  interest-bearing  debt  in  1994  and  1993 was
$17,632,000 and $8,258,000, respectively.
 
LIQUIDITY AND CAPITAL RESOURCES
 
   
  NET CASH USED IN OPERATING ACTIVITIES
    
 
   
    For the  six  months  ended  June  30, 1996,  net  cash  used  in  operating
activities decreased to $0.1 million from $3.0 million for the comparable period
in 1995. Cash provided by operations, before
    
 
                                       31
<PAGE>
   
changes in operating assets and liabilities, increased to $4.2 million from $0.1
million  for the comparable period in 1995 due primarily to the 1995 Acquisition
and the increase in results of operations therefrom.
    
 
   
  NET CASH USED IN INVESTING ACTIVITIES
    
 
   
    Net cash used in investing activities for the six months ended June 30, 1996
was  $49.7  million.  Approximately  $42.5   million  was  used  for  the   1996
Acquisition,  $5.2 million was used for other  oil and gas expenditures and $2.0
million was used for other property  and equipment. For the year ended  December
31, 1995, net cash used in investing activities was $62.5 million. Approximately
$46.6  million was used for the  1995 Acquisition, $10.6 million for exploration
and development  activities, $4.3  million for  two additional  acquisitions  of
producing  oil and gas properties and  $1.0 million primarily for other property
and equipment.
    
 
   
NET CASH PROVIDED BY FINANCING ACTIVITIES
    
 
   
    The Company entered into  a $125.0 million senior  credit agreement in  June
1996,  against which  $122.0 million  was initially  funded. Approximately $74.5
million was for the extension and  refinancing of prior debt, $42.5 million  was
used  for  the 1996  Acquisition  and approximately  $5.0  million was  used for
general corporate purposes.
    
 
  CAPITAL SOURCES
 
    Funding for the Company's business activities has historically been provided
by bank financings, cash  flow from operations,  private equity sales,  property
divestitures   and  joint  ventures  with  industry  participants.  The  Company
completed a $10 million private equity placement in February 1995. Subsequently,
the 1995 Acquisition and the 1996 Acquisition were substantially funded by  bank
financings.  The Company plans to finance  its continuing operations and execute
its business strategy  with cash  flow from  operations, net  proceeds from  the
Offerings and borrowings under the Credit Facility.
 
   
    While  the Company  regularly engages  in discussions  relating to potential
acquisitions, the Company has no present agreement, commitment or  understanding
with  respect to any such acquisition, other than the acquisition of undeveloped
acreage and royalty  and overriding royalty  interests in its  normal course  of
business.  Any future acquisition  may require additional  financing and will be
dependent upon financing arrangements available at the time.
    
 
   
    The Company believes that cash flow  from operations will be sufficient  for
anticipated  operating  and capital  expenditure requirements.  However, because
future cash flows and the availability of  financing are subject to a number  of
variables  beyond  the Company's  control, there  can be  no assurance  that the
Company's capital resources  will be  sufficient to  maintain currently  planned
levels  of capital expenditures. The Company's historical and pro forma earnings
for the year ended December 31, 1995 and the six months ended June 30, 1996 were
insufficient to  cover  fixed  charges. Although  the  Company's  earnings  were
insufficient to cover fixed charges for these periods, the Company does not have
covenants  in  the Indenture  or the  Credit Facility  requiring the  Company to
maintain a specific ratio of earnings to fixed charges. However, if the  Company
is  unable to generate sufficient cash flow from operations to service its debt,
it may be  required to refinance  all or a  portion of its  debt, including  the
Notes,  or to obtain  additional financing. There  can be no  assurance that any
such refinancing would  be possible or  that any additional  financing could  be
obtained. See "Risk Factors -- Significant Leverage and Debt Service."
    
 
   
    The  Company has received a commitment  from NationsBank of Texas, N.A. (the
"Bank") to provide the Credit Facility  to the Company following the  Offerings.
The  Credit  Facility will  provide  for a  revolving  line of  credit  with the
availability of funds and  letters of credit being  subject to a borrowing  base
determination  at least semi-annually. The borrowing base will initially provide
for availability  of up  to  $50.0 million,  none of  which  is expected  to  be
outstanding  immediately following  the Offerings.  Borrowings under  the Credit
Facility will  bear  interest  at  the  Company's  option  at  a  floating  rate
    
 
                                       32
<PAGE>
   
which  is  at or  above  the NationsBank,  N.A. prime  rate  or the  LIBOR rate,
depending on  the  percentage  of  committed funds  which  have  been  borrowed.
Interest  will be  payable quarterly and  principal will be  amortized in twelve
equal installments commencing  two years following  the execution of  definitive
loan  documents. Under the Credit Facility, the Company will be obligated to pay
certain fees to the Bank, including a commitment fee based on the unused portion
of the  commitment.  The  Credit Facility  will  contain  customary  restrictive
covenants (including restrictions on the payment of dividends and the incurrence
of  additional indebtedness) and will require  the Company to maintain a current
ratio of  not less  than 1.0  to 1.0,  a ratio  of Adjusted  EBITDA to  interest
expense  of not less than 2.0  to 1.0 and a minimum  tangible net worth. At June
30, 1996, on a pro forma basis, the Company's current ratio would have been  2.7
to  1.0, the ratio of Adjusted EBITDA to interest expense would have been 2.1 to
1.0 and the  Company would have  exceeded the  tangible net worth  test by  $1.4
million.  The Company believes it  will be in compliance  with such covenants on
the date of closing of the Offerings. Borrowings under the Credit Facility  will
be  secured by not less than 70%  of the Company's assets. The Bank's commitment
is subject to certain conditions, including completion of the Offerings and  the
Corporate  Reorganization and application of the net proceeds therefrom to repay
the Company's prior secured indebtedness. See "Use of Proceeds."
    
 
    Although certain of  the Company's  costs and  expenses may  be affected  by
inflation, inflationary costs have not had a significant effect on the Company's
results of operations.
 
  CAPITAL EXPENDITURES
 
    The  Company requires capital primarily for the exploration, development and
acquisition of oil and gas properties, the repayment of indebtedness and general
working capital needs.
 
   
    The following  table  sets  forth  costs incurred  by  the  Company  in  its
development,   exploration  and   acquisition  activities   during  the  periods
indicated.
    
 
   
<TABLE>
<CAPTION>
                                                                                           SIX MONTHS
                                                            YEARS ENDED DECEMBER 31,          ENDED
                                                         -------------------------------    JUNE 30,
                                                           1993       1994       1995         1996
                                                         ---------  ---------  ---------  -------------
                                                                       (IN THOUSANDS)
<S>                                                      <C>        <C>        <C>        <C>
Development costs......................................  $      --  $      --  $     158   $       607
Exploration costs......................................      2,017      2,167      5,627         3,881
Acquisition costs:
  Unproved properties..................................        829      1,232      1,742         1,712
  Proved properties....................................      4,665      9,649     52,470        41,791
                                                         ---------  ---------  ---------  -------------
Total..................................................  $   7,511  $  13,048  $  59,997   $    47,991
                                                         ---------  ---------  ---------  -------------
                                                         ---------  ---------  ---------  -------------
</TABLE>
    
 
   
    The Company anticipates that costs  incurred for 1996 will be  approximately
$64.8  million, of which  approximately $42.5 million was  expended for the 1996
Acquisition, and approximately  $5.2 million  was expended  for exploration  and
development activities during the six months ended June 30, 1996.
    
 
   
  DELIVERY COMMITMENT
    
 
   
    In  November 1995, the Company entered  into gas sales agreements whereby it
committed to  delivery of  a total  of 2,379,000  Mmbtu, from  December 1,  1995
through December 1, 1996, for a total fixed price of $3,429,610. Income from the
agreements is recognized in the period of delivery.
    
 
                                       33
<PAGE>
                            BUSINESS AND PROPERTIES
 
GENERAL
 
   
    Costilla  is  an  independent  energy company  engaged  in  the exploration,
acquisition and development  of oil  and gas properties.  The Company's  primary
operations are in the Permian Basin area of Texas and New Mexico, the Gulf Coast
and  the Rocky  Mountain regions. The  Company's strategy  focuses on increasing
reserves through targeted exploration programs, the exploitation of its existing
properties  and  selective  property  acquisitions.  In  addition,  the  Company
recently  acquired  an interest  in an  entity  which has  a concession  for the
development of mineral interests in the Republic of Moldova, in Eastern  Europe.
The  Company  also  has  minor  interests  in  the  domestic  gas  gathering and
transmission business.
    
 
   
    The Company's  predecessor began  operating  in 1988  with the  strategy  of
acquiring and exploiting undervalued oil and gas properties, and at December 31,
1992  had net proved reserves  of 4.7 MMBOE. Since  January 1, 1993, the Company
has successfully closed seven  transactions for an  aggregate purchase price  of
approximately $101 million. As of April 1, 1996, the Company had total estimated
net  proved reserves (as defined  below) of 16.5 Mmbbls of  oil and 112.9 Bcf of
gas, aggregating 35.3 MMBOE, with a PV-10 Value of approximately $179.5 million,
assuming the 1996 Acquisition (as defined below) had occurred at April 1,  1996.
The  Company also has  a substantial undeveloped  acreage position consisting of
180,704 gross (165,166 net) acres at  June 30, 1996. The Company has  identified
in  excess of  200 drilling  locations of  which 78  are included  in its proved
reserves.
    
 
   
    Costilla  has  in-house  exploration   expertise  which  uses  3-D   seismic
technology  as  a  primary  tool  to  identify  drilling  opportunities  and has
experienced high rates of  success in each  of its first  two major 3-D  seismic
drilling  programs. Since 1994, the Company has  drilled 26 wells based on these
3-D surveys,  23  of  which  have been  productive.  The  Company  has  recently
completed  two additional 3-D surveys and intends to commence drilling on one of
these acreage blocks in the second half of 1996. The Company currently plans  to
drill 81 wells through 1997 based on its 3-D surveys.
    
 
   
    Since   1993,  Costilla  has  generated   significant  growth  in  reserves,
production and  Adjusted  EBITDA. The  Company  increased its  estimated  proved
reserves from 6.0 MMBOE at December 31, 1993 to 35.3 MMBOE at April 1, 1996 (pro
forma  for the 1996 Acquisition), representing  a compound annual growth rate of
114%. This reserve growth has been achieved at an average all-in finding cost of
$3.60 per BOE over such period, a level which the Company believes is lower than
industry averages. Concurrently,  the Company  increased its  average net  daily
production  from 827 BOE for the year ended  December 31, 1993 to 10,703 BOE for
the three months  ended March  31, 1996 (pro  forma for  the 1996  Acquisition),
representing a compound annual growth rate of 195%. Adjusted EBITDA increased at
a  240% compound annual growth rate from  $1.8 million for 1993 to $20.8 million
for 1995 (pro forma for the 1995 Acquisition and the 1996 Acquisition).
    
 
BUSINESS STRATEGY
 
   
    The Company's strategy is to increase  its oil and gas reserves,  production
and  cash flow from operations through  a two-pronged approach which combines an
active exploration program  using 3-D seismic  and other technological  advances
with the acquisition and exploitation of producing properties. The Company seeks
to  reduce its operating and commodity risks by holding a geographically diverse
portfolio of properties,  the reserves attributable  to which are  approximately
balanced  between oil and gas. The Company  also seeks to manage the elements of
its business strategy  through the  operation of  a significant  portion of  its
properties,  the use of a  rate of return analysis  and the direct marketing and
hedging of its oil  and gas production. The  elements of the Company's  strategy
may be further described as follows:
    
 
- - EXPLORATION  EFFORTS.  The Company uses extensive geological and geophysical
  analysis to carefully focus its 3-D  seismic surveys. This focus allows  the
  Company to successfully direct the size and scope of its exploration program
  in  order  to  improve  the likelihood  of  success  while  managing overall
  exploration  costs.  The  Company's  exploration  efforts  are  concentrated
  currently on
 
                                       34
<PAGE>
   
  known  producing regions.  The Company plans  to drill  24 exploratory wells
  during the  last half  of 1996  and 36  exploratory wells  in 1997.  Capital
  budgeted  for exploration activities is $8.1 million for the last six months
  of 1996 and $10.8 million for 1997.
    
 
   
- - EXPLOITATION  ACTIVITIES.    The  Company  is  actively  pursuing   numerous
  exploitation  opportunities within its  existing properties, including areas
  where no  proved reserves  are currently  assigned. Exploitation  activities
  currently  in  progress  include  a  carbon  dioxide  flood,  recompletions,
  workovers and  infill  and  horizontal drilling  and  a  secondary  recovery
  project.  The Company's capital  budget for such  activities is $8.5 million
  for the last six months  of 1996 and $9.2  million for 1997, which  includes
  the  drilling of 12  development wells in  1996 and 13  development wells in
  1997.
    
 
- - PROPERTY ACQUISITIONS.   The Company seeks  to acquire producing  properties
  where  it has identified  opportunities to increase  production and reserves
  through both  exploitation  and  exploration  activities.  The  Company  has
  increased  the  value  of  its  acquisitions  by  aggressively  managing the
  operations of existing proved properties and by successfully identifying and
  developing previously  unproved reserves  on acquired  acreage. The  Company
  seeks  to  acquire  reserves  which will  fit  its  existing  portfolio, are
  generally not being actively marketed and  where a negotiated sale would  be
  the  method of  purchase. The  Company does  not rely  on major  oil company
  divestitures or property auctions.
 
- - PROPERTY DIVERSIFICATION.   The Company  holds a  portfolio of  oil and  gas
  properties  located  in the  Permian  Basin, the  Gulf  Coast and  the Rocky
  Mountain regions. The Company believes that by conducting its activities  in
  distinct  regions it is able to reduce commodity price and other operational
  risks. The Company's Moldovan interest is an extension of this strategy  and
  can be characterized by low initial costs, significant reserve potential and
  the  availability of  technical data  that may  be further  developed by the
  Company.
 
   
- - CONTROL OF OPERATIONS.  The Company prefers to operate and own the  majority
  working  interest in its properties. This allows the Company greater control
  over  future  development,  drilling,  completing  and  lifting  costs   and
  marketing  of  production.  At April  1,  1996, the  Company  operated wells
  constituting approximately 65% of its total  PV-10 Value (pro forma for  the
  1996 Acquisition).
    
 
SIGNIFICANT ACQUISITIONS
 
   
    1995  ACQUISITION.  In  a $46.6 million acquisition  completed in June 1995,
the Company acquired a group  of oil and gas  properties located in the  Permian
Basin,  Gulf Coast and Rocky  Mountain regions. At the  date of acquisition, the
net proved reserves included 7.1 Mmbbls of oil and 44.1 Bcf of gas,  aggregating
14.4  MMBOE. From  the date  of acquisition  until March  31, 1996,  the Company
produced 1.1  MMBOE from  the acquired  properties  and sold  a portion  of  the
acquired  properties for approximately  $3.6 million. At April  1, 1996, the net
proved reserves  of  the remaining  properties  were 13.4  MMBOE.  The  acquired
properties also included 103,010 gross (93,786 net) undeveloped acres.
    
 
   
    1996 ACQUISITION.  In June 1996, the Company acquired a group of oil and gas
properties  located primarily  in the Permian  Basin and Gulf  Coast regions for
approximately $42.5  million.  This  acquisition included  properties  with  net
proved  reserves at  April 1, 1996  of 5.0  Mmbbls of oil  and 33.5  Bcf of gas,
aggregating 10.6  MMBOE.  The acquired  properties  also included  40,092  gross
(14,512  net) undeveloped acres and a pipeline located in Pennsylvania which had
an allocated purchase price of $3.5 million.
    
 
                                       35
<PAGE>
PRINCIPAL PROPERTIES
 
   
    The following table sets forth certain information, as of April 1, 1996 (pro
forma for the  1996 Acquisition),  which relates to  the principal  oil and  gas
properties owned by the Company.
    
 
   
<TABLE>
<CAPTION>
                                                                                 PROVED RESERVES
                                                            ----------------------------------------------------------
                                                                                              TOTAL OIL    PERCENT OF
                                                              GROSS       OIL        GAS     EQUIVALENT    TOTAL OIL
REGION                                                        WELLS     (MBBLS)    (MMCF)      (MBOE)      EQUIVALENT
- ----------------------------------------------------------  ---------  ---------  ---------  -----------  ------------
<S>                                                         <C>        <C>        <C>        <C>          <C>
Permian Basin.............................................      1,890      9,200     55,200      18,400         52.1%
Gulf Coast................................................        968      2,054     38,440       8,461         24.0
Rocky Mountain............................................        236      4,526     12,886       6,674         18.9
Other.....................................................        428        696      6,394       1,762          5.0
                                                            ---------  ---------  ---------  -----------       -----
Total.....................................................      3,522     16,476    112,920      35,297        100.0%
                                                            ---------  ---------  ---------  -----------       -----
                                                            ---------  ---------  ---------  -----------       -----
</TABLE>
    
 
   
    PERMIAN  BASIN.  At  April 1, 1996,  52.1% of the  Company's proved reserves
were concentrated in  the Permian  Basin, an approximately  70-county region  in
West  Texas and Southeast  New Mexico. The Company's  production comes from well
known fields such  as the  Spraberry Trend,  Sawyer Canyon,  Goldsmith Unit  and
Susan  Peak. The  majority of the  Company's producing intervals  in the Permian
Basin range from 4,500 feet to 9,500 feet in depth.
    
 
    The Company  has several  exploratory projects  in the  Permian Basin  based
primarily on 3-D seismic surveys. The most significant include:
 
   
    EDWARDS/MCELROY  RANCH PROSPECT, ECTOR AND  CRANE COUNTIES, TEXAS.  Costilla
has identified 75 drilling  locations on the Company's  9,849 gross (4,334  net)
acres  in this prospect  based on 3-D  seismic data. Since  January 1, 1996, the
Company has drilled four successful wells  on this prospect which have  resulted
in three separate field discoveries. In addition, these wells have confirmed the
Strawn  and  Wolfcamp  trends  defined by  the  Company's  extensive approximate
50-square mile 3-D  seismic project undertaken  jointly with Texaco  Exploration
and  Production  Inc.  ("Texaco"). Two  additional  wells are  being  drilled or
completed on seismic delineated features. The Company plans to drill 25 wells in
this trend through  1997. The  Company's working  interest in  this prospect  is
approximately 44%.
    
 
   
    Costilla  and Texaco are also developing  a Queen Sand field identified from
the Edwards/McElroy  Ranch seismic  program. The  four producing  wells  drilled
through June 30, 1996 are producing an aggregate of approximately 80 Bbls of oil
per  day and  the Company  has participated  in the  drilling of  two additional
productive wells subsequent to June 30,  1996. Drilling of six additional  Queen
Sand  wells  is  anticipated  through  1997,  with  the  field  ultimately being
developed on a planned waterflood pattern  in order to maximize recovery of  the
oil in place.
    
 
   
    MCGYVER-GREEN  ACRES  PROSPECT,  HOWARD  COUNTY,  TEXAS.    The  Company has
identified 41 drilling locations in  this prospect based on information  derived
from approximately 30 square miles of 3-D seismic data that the Company acquired
on  the area in 1994. The  Talbot Fuller well was the  first well drilled by the
Company on this prospect and was completed in the Canyon Lime formation at 8,200
feet in August 1994. Since completion, the well has produced 62,000 Bbls of  oil
and  207 Mmcf of gas, and averaged 77 Bbls of oil per day and 320 Mcf of gas per
day during June  1996. Subsequent to  the first well,  14 additional wells  have
been drilled on this prospect of which 11 are productive. The Company intends to
drill  six additional wells during the balance of 1996 on its 9,148 gross (6,587
net)  acres.  The   Company's  working  interest   in  this  prospect   averages
approximately 72%.
    
 
    The  following two 3-D programs currently being undertaken by the Company in
the Permian Basin are expected to provide additional drilling locations:
 
    WILSON RANCH 3-D PROJECT, PECOS COUNTY, TEXAS.  The Wilson Ranch is  located
in  northeastern Pecos County,  approximately 10 miles west  of the Yates field.
The Company recently completed an  approximate 17-square mile seismic survey  on
the    project.   A   second   phase   will    be   initiated   in   the   first
 
                                       36
<PAGE>
   
quarter of 1997.  The project  presents several  potential exploration  targets,
including  the Queen, San Andres, Wolfcamp, Devonian and Ellenberger formations,
found at depths  ranging from 1,600  to 8,000  feet. The Company  has agreed  to
lease 3,750 gross acres on this 50,000 acre ranch. Upon acquiring the lease, the
Company  intends to sell up to one-half of its approximate 75% working interest.
The Company  believes that  there is  significant additional  potential in  this
area.
    
 
   
    DAVAN  UNIT 3-D PROJECT, STONEWALL COUNTY, TEXAS.  The Company has completed
another 3-D seismic project with Texaco to further develop the  Company-operated
Davan Unit. The project involves a 3-D seismic evaluation of approximately 3,200
gross  acres adjacent  to a  Company-operated waterflood  which has  produced in
excess of three Mmbbls of oil. An exploratory well is scheduled on this prospect
for the first quarter of 1997.
    
 
    Two examples of the  Company's current exploitation  efforts in the  Permian
Basin include:
 
   
    EAST  GOLDSMITH FIELD  C02 PROJECT, ECTOR  COUNTY, TEXAS.   The Company owns
3,053 gross  (2,073 net)  acres in  this  field located  20 miles  northwest  of
Midland,  Texas. Since  its discovery,  the field has  produced in  excess of 17
Mmbbls of  oil from  seven formations.  The most  productive zones  in the  East
Goldsmith Field have been the San Andres and Holt formations, both of which have
been  subject  to  secondary recovery  by  waterflooding. The  Company  has been
analyzing a tertiary recovery project in those formations using CO2, and intends
to initiate the  project in the  fourth quarter of  1996. The Company's  working
interest in this project averages approximately 87%.
    
 
   
    SUSAN PEAK FIELD WORKOVER AND HORIZONTAL DRILLING PROGRAM, TOM GREEN COUNTY,
TEXAS.   The Company recently completed the  first horizontal well in this field
located south of San  Angelo, Texas, in  which it owns  a 100% working  interest
until  payout. Production from this well drilled in the Strawn formation was 110
Bbls of oil per day and 240 Mcf of gas per day on June 30, 1996. Since  February
1996,  with only  two workovers  and the  new horizontal  well, the  Company has
increased Susan Peak production  from approximately 30 Bbls  of oil per day  and
700  Mcf of gas per day  to a current rate of  approximately 130 Bbls of oil per
day and 1,400 Mcf of gas per day. Two possible horizontal drilling locations and
additional workover  candidates remain  on  this 7,461  gross (3,730  net)  acre
lease. The Company's working interest in this project ranges from 50% to 100%.
    
 
   
    GULF  COAST.  At April 1, 1996,  24.0% of the Company's proved reserves were
concentrated in the Gulf Coast region.  The Company's production in this  region
primarily  comes from  known formations  such as  Frio, Yegua,  Austin Chalk and
Wilcox.
    
 
    The Company  plans  to use  its  expertise in  aggressively  developing  3-D
opportunities on the extensive acreage position it holds in the region. Examples
of such exploration projects in progress include:
 
   
    SEALY  PROSPECT, AUSTIN COUNTY, TEXAS.  The Sealy Field, consisting of 3,534
gross (1,767  net) acres,  was  acquired in  the  1995 Acquisition.  The  Wilcox
formation in this field has produced over 66 Bcf of gas and there are subsurface
indications  of  the presence  of several  fault blocks  that lie  untested. The
Company's working interest in  this prospect is 100%.  The Company is  currently
attempting  to acquire additional acreage in this prospect prior to initiating a
3-D survey in late 1996 or 1997.
    
 
   
    SOUTHWEST SPEAKS, LAVACA COUNTY, TEXAS.   This project, consisting of  5,078
gross  (2,539 net) acres, was also acquired  in the 1995 Acquisition and is held
by several  shallow Company-operated  wells.  Multiple producing  horizons  from
shallow  depths to below 14,000 feet have produced over 199 Bcf of gas from this
highly faulted field. A recent well was completed in the Rainbow Wilcox sand  on
acreage  adjoining  Costilla's  lease. A  well,  in  which Costilla  holds  a 5%
interest as a result of a farmout, has also been completed on Costilla's  lease.
The  Company's plans are to conduct a 3-D survey in the Speaks area in late 1996
or 1997. The Company's working interest in this prospect is approximately 50%.
    
 
    BORCHERS FIELD,  LAVACA COUNTY,  TEXAS.   This  field  was acquired  by  the
Company  in  the 1996  Acquisition. The  property  is on  trend with  the Speaks
project and is also a highly faulted field
 
                                       37
<PAGE>
   
providing opportunity for further development. The Borchers Field has produced a
total of 17.5  Bcf of gas  from two Wilcox  sands. Costilla has  a 100%  working
interest  in this  field consisting  of 1,321 gross  and net  acres. The Company
plans to conduct a 3-D survey in the Borchers Field in 1997.
    
 
    Examples of exploitation activities in this region include:
 
   
    JOSEY RANCH LEASE,  HARRIS COUNTY,  TEXAS.   Two examples  of the  Company's
production  enhancement  of  Gulf  Coast  properties  were  undertaken  on  this
prospect. When the lease  was acquired in the  1995 Acquisition, production  had
nearly  ceased. Through  a series of  workovers, the Company  has improved daily
production, as of June 30, 1996, to 63 Bbls of oil per day and 73 Mcf of gas per
day. In addition, Costilla has  participated in a 13,000  foot test well on  the
Josey  Ranch lease to test the Wilcox formation. The well was completed in April
1996 and has consistently produced approximately  1,000 Mcf of gas per day.  The
Josey  Ranch lease covers 1,661 gross (649 net) acres, and the Company's working
interest in this prospect is approximately 39%.
    
 
   
    PERSONVILLE, LIMESTONE COUNTY, TEXAS.  The Company has recently completed an
11,200 foot Cotton Valley well, which is currently producing 0.7 Mmcf of gas per
day. The Company is  preparing to stimulate  the well in  order to increase  its
production.  The  Company  is preparing  to  drill  an additional  well  on this
prospect. Costilla leases 412  gross (111 net) acres  in this prospect, and  has
identified  two additional  drilling locations. The  Company is  the operator of
this prospect and its working interest is approximately 30%.
    
 
    AUSTIN CHALK, BRAZOS, BURLESON, FAYETTE  AND LEE COUNTIES, TEXAS.   Costilla
acquired  the majority of the working interest  in nine gross Austin Chalk wells
in the  1995 Acquisition  and an  additional 80  gross Austin  Chalk wells  were
included  in the 1996 Acquisition. The  Company intends to enhance production on
certain of these wells through stimulation and workover activities, and  analyze
further  development potential. Costilla has 30,414  gross (20,985 net) acres in
the  Austin  Chalk  area,  and  its  working  interest  in  this  area  averages
approximately 69%.
 
   
    ROCKY  MOUNTAIN.  At April  1, 1996, 18.9% of  the Company's proved reserves
were concentrated in the  Rocky Mountain region,  which includes Montana,  North
Dakota, Wyoming, Colorado and Utah.
    
 
   
    The  Company  has a  number of  opportunities in  the Rocky  Mountain region
involving 3-D seismic surveys, exploratory drilling and exploitation activities.
Examples of each of these opportunities are:
    
 
    RAYMOND FIELD, SHERIDAN COUNTY, MONTANA.   Since its discovery in 1972,  the
Raymond  Field  has  produced  over  five  Mmbbls  of  oil  from  five different
formations. Daily production from the field  has increased from 180 Bbls of  oil
per  day since its acquisition in  June 1995 to 369 Bbls  of oil per day at June
30, 1996 primarily as a result of the Company's improved operations. The Company
plans a 3-D program on  its 960 gross and net  acres in this field. The  Company
owns a 100% working interest in this prospect.
 
    OUTLOOK  FIELD, SHERIDAN COUNTY,  MONTANA.  The  Company undertook its first
Rocky Mountain 3-D  seismic survey in  the Outlook area  to further develop  the
field.  Three  drilling locations  were identified  from  the data.  The Company
anticipates commencing  an Outlook  test well  in September  1996 that  will  be
drilled to 10,500 feet, a depth sufficient to test several different formations.
Costilla  leases 5,168 gross (1,292 net) acres in the Outlook prospect, and owns
an approximate 25% working interest in this prospect.
 
   
    NATURAL BUTTES FIELD, UINTAH COUNTY, UTAH.  The Company owns a 100%  working
interest  in 1,280 gross  and net acres  in this prospect.  Development by prior
owners was  on 640-acre  spacing  while offset  acreage  has been  developed  on
80-acre  spacing. Low gas  prices in the  area have precluded  the assignment of
proved reserves to  any undeveloped acres.  As gas prices  improve, the  Company
plans to drill additional wells on the prospect.
    
 
                                       38
<PAGE>
    The  Company owns an interest in  significant acreage positions in the Rocky
Mountain region  which are  operated by  third parties  and are  the subject  of
active exploitation efforts. The most significant property is:
 
   
    CIRCLE  RIDGE FIELD,  FREMONT COUNTY, WYOMING.   The Circle  Ridge Field, in
which the  Company has  an  approximate 18%  working  interest, is  operated  by
Marathon Oil Company. This field is an approximate 1,100 acre waterflood located
in  the Wind River Basin  of Wyoming, approximately 30  miles north of Riverton,
Wyoming. There are 97  active producing wells and  10 active injection wells  in
the  field.  Production  originates  from the  Phosphoria,  Tensleep  and Amsden
formations that are  present at  depths ranging from  500 to  2,000 feet.  Since
January  1995,  45 projects  have been  completed in  the field.  These projects
include recompletions,  stimulation  treatments and  reactivations,  which  have
increased production from 1,469 Bbls of oil per day in January 1995 to a rate of
1,778 Bbls of oil per day for June 1996. The operator has several other projects
scheduled  for the remainder of 1996 and is evaluating various different methods
of enhanced oil recovery for the field.
    
 
MARKETING ARRANGEMENTS
 
   
    The Company utilizes an active marketing program for a portion of its  crude
oil  production in order to enhance the net price it receives. The Company sells
its crude oil production from operated  properties in North Dakota, Montana  and
Wyoming,  at the  lease level  to an oil  transportation company  for the posted
price, plus an agreed upon bonus,  with a corresponding agreement to  repurchase
this production at its delivery point (typically, Cushing, Oklahoma) for a price
equal  to the then  posted price for  West Texas Intermediate  crude oil less an
agreed upon  deduction for  transportation and  quality differentials,  if  any,
between  the repurchased  crude oil and  West Texas Intermediate  crude oil. The
Company then employs  a broker to  resell its crude  oil to end  users (such  as
refineries)  on a  month-to-month basis.  The lease  level sales  and repurchase
contracts are  typically of  six  months duration.  With  respect to  its  other
operated  oil production  (primarily located  in Texas),  the Company  employs a
similar price enhancement strategy, although  the repurchase feature is  absent.
Instead,  the lease level  purchaser resells the  crude oil to  end users at the
delivery point for the account of the Company. While these arrangements have the
effect of increasing the net price the Company receives for its crude oil,  such
arrangements  do  not have  the  effect of  limiting  the Company's  exposure to
movements in crude  oil prices. The  Company markets its  gas production at  the
lease  level pursuant to month-to-month contracts. No single purchaser of oil or
gas accounted for in  excess of 10% of  the Company's consolidated revenues  for
the year ended December 31, 1995.
    
 
RISK MANAGEMENT
 
   
    The  Company typically  employs a  strategy of  purchasing put  options on a
portion of its anticipated oil and gas production. This strategy is designed  to
protect  the  Company from  significant downward  movements in  commodity prices
while preserving the benefit  of rising prices. The  Company does not  establish
hedges  in  excess  of  its anticipated  production.  Upon  consummation  of the
Offerings, substantially  all of  the Company's  debt will  be fixed  rate.  The
Company's  current  position with  regard  to its  1996  commodity hedges  is as
follows:
    
 
   
    OIL SALES.  The Company has purchased  put options to provide a floor  price
for  3,000 Bbls  of oil per  day of its  oil production for  August 1996 through
December 1996. These put options currently in place represent approximately  52%
of the Company's estimated oil production for August 1996 through December 1996.
The  floor price  the Company  has an  agreement to  receive is  $18.00 per Bbl,
irrespective of the prices actually paid by  purchasers of the oil at the  lease
level.
    
 
   
    GAS  SALES.   The Company  has purchased put  options which  provide a floor
price for 900,000 Mmbtu's per month of its gas production through October  1996.
The  put options currently in place represent approximately 84% of the Company's
estimated gas production for  July 1996 through October  1996. The floor  prices
with  respect to such put options varies from $1.65 to $1.75 per Mmbtu depending
on the area in which the gas is produced.
    
 
                                       39
<PAGE>
OIL AND GAS RESERVES
 
   
    The Company's estimated total  proved and proved  developed reserves of  oil
and  gas as of December 31, 1993, 1994 and 1995, and as of April 1, 1996 were as
follows:
    
 
   
<TABLE>
<CAPTION>
                                                       AS OF DECEMBER 31,
                               ------------------------------------------------------------------       PRO FORMA
                                                                                                         APRIL 1,
                                        1993                   1994                  1995                1996 (1)
                               ----------------------  --------------------  --------------------  --------------------
                                   OIL         GAS        OIL        GAS        OIL        GAS        OIL        GAS
                                 (MBBLS)     (MMCF)     (MBBLS)    (MMCF)     (MBBLS)    (MMCF)     (MBBLS)    (MMCF)
                               -----------  ---------  ---------  ---------  ---------  ---------  ---------  ---------
<S>                            <C>          <C>        <C>        <C>        <C>        <C>        <C>        <C>
Proved developed producing...       1,785      13,268      2,632     15,757      8,338     50,542     13,122     76,439
Proved developed non-
 producing...................           0           0          0        583        228      6,851        429      7,930
Proved undeveloped...........         580       8,351      1,377     11,172      2,222     20,759      2,925     28,551
                                    -----   ---------  ---------  ---------  ---------  ---------  ---------  ---------
  Total proved...............       2,365      21,619      4,009     27,512     10,788     78,152     16,476    112,920
                                    -----   ---------  ---------  ---------  ---------  ---------  ---------  ---------
                                    -----   ---------  ---------  ---------  ---------  ---------  ---------  ---------
</TABLE>
    
 
- ------------------------------
   
(1)  Assumes that the 1996 Acquisition had been consummated at April 1, 1996.
    
 
    The following table sets forth the future net cash flows from the  Company's
estimated proved reserves:
 
   
<TABLE>
<CAPTION>
                                                                            DECEMBER 31,              PRO FORMA
                                                                  ---------------------------------   APRIL 1,
                                                                    1993       1994        1995        1996(1)
                                                                  ---------  ---------  -----------  -----------
                                                                                  (IN THOUSANDS)
<S>                                                               <C>        <C>        <C>          <C>
Future net cash flows before income taxes.......................  $  47,213  $  68,596  $   188,337  $   297,002
Future net cash flows before income taxes, discounted at 10%....  $  26,377  $  36,779  $   113,296  $   179,527
</TABLE>
    
 
- ------------------------------
   
(1)  Assumes that the 1996 Acquisition had been consummated at April 1, 1996.
    
 
   
    The  reserve estimates reflected above for 1993, 1994 and 1995 were prepared
by the Company. The Company's 1995  estimates of gross reserves with respect  to
certain  of the Company's producing properties  were subject to a limited review
by Williamson of the Company's engineering analysis covering approximately 54.0%
of the Company's proved reserves at such date. The pro forma estimates for April
1, 1996,  including  the  properties  acquired in  the  1996  Acquisition,  were
prepared  by Williamson  and are part  of reports  on the Company's  oil and gas
properties prepared by  Williamson, a summary  of which is  set forth herein  as
Appendix A.
    
 
    The  reserve  data  set forth  herein  present estimates  only.  In general,
estimates of economically recoverable oil and gas reserves and of the future net
revenues therefrom are based upon an number of variable factors and assumptions,
such as historical production from  the subject properties, the assumed  effects
of regulation by governmental agencies and assumptions concerning future oil and
gas  prices and future operating costs, all  of which may vary considerably from
actual  results.  All  such  estimates  are  to  some  degree  speculative,  and
classifications   of  reserves  are  only  attempts  to  define  the  degree  of
speculation  involved.  For  these   reasons,  estimates  of  the   economically
recoverable  oil  and  gas  reserves attributable  to  any  particular  group of
properties, classifications  of such  reserves  based on  risk of  recovery  and
estimates  of the future net revenues  expected therefrom, prepared by different
engineers or by the same engineers  at different times, may vary  substantially.
The Company therefore emphasizes that the actual production, revenues, severance
and  excise taxes,  development and operating  expenditures with  respect to its
reserves will  likely vary  from such  estimates, and  such variances  could  be
material.
 
    Estimates with respect to proved reserves that may be developed and produced
in  the future are often based upon  volumetric calculations and upon analogy to
similar types of reserves rather than
 
                                       40
<PAGE>
actual production history. Estimates based  on these methods are generally  less
reliable than those based on actual production history. Subsequent evaluation of
the same reserves based upon production history will result in variations, which
may be substantial, in the estimated reserves.
 
    In  accordance with applicable  requirements of the  Securities and Exchange
Commission, the estimated discounted future  net revenues from estimated  proved
reserves  are based on  prices and costs as  of the date  of the estimate unless
such prices or costs  are contractually determined at  such date. Actual  future
prices  and costs may be materially higher  or lower. Actual future net revenues
also will be affected  by factors such as  actual production, supply and  demand
for oil and natural gas, curtailments or increases in consumption by natural gas
purchasers,  changes in governmental  regulations or taxation  and the impact of
inflation on costs.
 
EXPLORATION AND DEVELOPMENT ACTIVITIES
 
   
    The Company  drilled, or  participated  in the  drilling of,  the  following
number  of wells during the periods indicated. At June 30, 1996, the Company was
in the process of drilling two gross (0.49 net) wells and was in the process  of
completing  three gross (1.16 net) wells as producers which are not reflected in
the following table.
    
   
<TABLE>
<CAPTION>
                                                              1993                    1994                    1995
                                                     ----------------------  ----------------------  ----------------------
                                                        GROSS        NET        GROSS        NET        GROSS        NET
                                                     -----------  ---------  -----------  ---------  -----------  ---------
<S>                                                  <C>          <C>        <C>          <C>        <C>          <C>
Exploratory:
  Productive.......................................           3        0.83           9        2.27          10        4.58
  Dry..............................................           2        1.06          10        3.73           6        2.57
                                                            ---         ---         ---         ---         ---         ---
    Total..........................................           5        1.89          19        6.00          16        7.15
                                                            ---         ---         ---         ---         ---         ---
                                                            ---         ---         ---         ---         ---         ---
Development:
  Productive.......................................          --          --          --          --           1        0.44
  Dry..............................................          --          --          --          --          --          --
                                                            ---         ---         ---         ---         ---         ---
    Total..........................................          --          --          --          --           1        0.44
                                                            ---         ---         ---         ---         ---         ---
                                                            ---         ---         ---         ---         ---         ---
Total:
  Productive.......................................           3        0.83           9        2.27          11        5.02
  Dry..............................................           2        1.06          10        3.73           6        2.57
                                                            ---         ---         ---         ---         ---         ---
    Total..........................................           5        1.89          19        6.00          17        7.59
                                                            ---         ---         ---         ---         ---         ---
                                                            ---         ---         ---         ---         ---         ---
 
<CAPTION>
 
                                                     SIX MONTHS ENDED JUNE
                                                            30, 1996
                                                     ----------------------
                                                        GROSS        NET
                                                     -----------  ---------
<S>                                                  <C>          <C>
Exploratory:
  Productive.......................................           3        1.74
  Dry..............................................           1        0.72
                                                            ---         ---
    Total..........................................           4        2.46
                                                            ---         ---
                                                            ---         ---
Development:
  Productive.......................................           4        1.98
  Dry..............................................          --          --
                                                            ---         ---
    Total..........................................           4        1.98
                                                            ---         ---
                                                            ---         ---
Total:
  Productive.......................................           7        3.72
  Dry..............................................           1        0.72
                                                            ---         ---
    Total..........................................           8        4.44
                                                            ---         ---
                                                            ---         ---
</TABLE>
    
 
    The Company  does  not  own  any  drilling rigs  and  all  of  its  drilling
activities  are  conducted by  independent  contractors under  standard drilling
contracts.
 
PRODUCTIVE WELL SUMMARY
 
    The following table  sets forth  the Company's  gross and  net interests  in
productive oil and gas wells as of June 30, 1996. Productive wells are producing
wells and wells capable of production.
 
   
<TABLE>
<CAPTION>
                                                                                                      ACTUAL (1)
                                                                                                 --------------------
                                                                                                   GROSS       NET
                                                                                                 ---------  ---------
<S>                                                                                              <C>        <C>
Oil wells......................................................................................      2,248     678.54
Gas wells......................................................................................      1,278     231.11
                                                                                                 ---------  ---------
    Total......................................................................................      3,526     909.65
                                                                                                 ---------  ---------
                                                                                                 ---------  ---------
</TABLE>
    
 
- ------------------------------
(1)  Does  not  include  royalty  and  overriding  royalty  interests  owned  by
     Statewide or the Company. See "-- Other Activities -- Minerals  Acquisition
     Program."  In addition, one well with  multiple completions is counted as a
     single well.
 
                                       41
<PAGE>
ACREAGE
 
   
    The following table sets forth  certain information regarding the  Company's
developed  and undeveloped  leasehold acreage  as of  June 30,  1996. Acreage in
which the Company's interest is limited to royalty, overriding royalty,  mineral
and similar interests (such as all acreage owned by Statewide) is excluded.
    
 
   
<TABLE>
<CAPTION>
                                                  DEVELOPED            UNDEVELOPED              TOTAL
                                             --------------------  --------------------  --------------------
REGION                                         GROSS       NET       GROSS       NET       GROSS       NET
- -------------------------------------------  ---------  ---------  ---------  ---------  ---------  ---------
<S>                                          <C>        <C>        <C>        <C>        <C>        <C>
Permian Basin..............................    126,091     50,151     65,741     55,669    191,832    109,819
Gulf Coast.................................    197,650     65,547     46,040     39,713    243,689    105,261
Rocky Mountain.............................      8,534      6,126     24,757     24,650     33,291     30,776
Other......................................     43,651     26,108     44,166     41,134     87,817     67,241
                                             ---------  ---------  ---------  ---------  ---------  ---------
    Total..................................    375,926    147,932    180,704    165,166    556,629    313,097
                                             ---------  ---------  ---------  ---------  ---------  ---------
                                             ---------  ---------  ---------  ---------  ---------  ---------
</TABLE>
    
 
OTHER ACTIVITIES
 
   
    MOLDOVA  CONCESSION  AGREEMENT.    In July  1995,  the  Republic  of Moldova
(located in Eastern Europe between Romania and the Ukraine) granted a Concession
Agreement to Resource Development Company Limited, L.L.C. ("Redeco"), an  entity
not  affiliated with the Company. The Company has paid Redeco $90,000 and agreed
to bear the first $2.0 million of Concession expenses ($1.2 million of which had
been expended through June 30, 1996) in  return for a 50.0% interest in  Redeco.
After the initial $2.0 million expenditure, the Company and the other members of
Redeco are each responsible for bearing 50.0% of future expenses. The Concession
Agreement  covers  the entire  country with  respect  to oil  and gas  and other
minerals and continues for various time  periods depending on the nature of  the
activity  conducted.  In  connection  with  two  previously  producing  but  now
abandoned fields,  Redeco's exclusive  rights continue  for 20  years.  Redeco's
exclusive period to explore throughout the remainder of Moldova expires in 2005,
but  Redeco will  maintain exclusive development  rights with  respect to fields
discovered for a period of 20 years from the date of first production from  such
field.  The Company has no material  fixed financial commitments with respect to
the Concession.
    
 
   
    MINERALS  ACQUISITION  PROGRAM.    Statewide,  a  Company  subsidiary,   was
organized  for the purpose  of acquiring overriding  royalty interests and other
types of non  cost-bearing mineral  interests underlying producing  oil and  gas
fields  primarily in Texas. The strategy of such acquisitions is to make blanket
offers to holders  of small  interests. From  inception through  June 30,  1996,
Statewide   expended  approximately  $3.3  million  in  acquiring  interests  in
approximately 1,400 properties.  Through June 30,  1996, Statewide had  received
revenues  from such interests aggregating approximately $1.5 million, as well as
proceeds from sales of such interests of approximately $150,000.
    
 
    GAS GATHERING AND  TRANSMISSION.   In 1996,  the Company  purchased a  45.0%
membership  interest (which reduces to 32.4%  when the Company and certain other
members recoup their original  investment) in Republic  Gas Partners, L.L.C.,  a
Texas  limited  liability  company  ("Republic"),  for  approximately  $800,000.
Republic owns  all of  the stock  of Mid  Louisiana Gas  Company, Mid  Louisiana
Marketing  Company and Mid Louisiana Gas Transmission Company (collectively, the
"Midla Companies").  The assets  of the  Midla Companies  include 409  miles  of
mainly  22-inch pipeline extending from the Monroe  field area south of the city
of  Baton  Rouge,  serving  various  Louisiana  and  Mississippi  municipal  and
industrial  customers along its  route. Mid Louisiana  Gas Company's pipeline is
subject  to  the  jurisdiction  of  the  Federal  Energy  Regulatory  Commission
("FERC").
 
    Valley,  a Company  subsidiary, owns a  small gas  gathering system, several
small gas plants,  11 salt water  disposal wells  located in each  of its  three
principal  regions and compressors used in the compression of gas located in the
Gulf Coast region. For the year ended December 31, 1995, Valley had revenues  of
$553,000  and net income of $264,000, substantially all of which were related to
transactions with Costilla.
 
                                       42
<PAGE>
    In the 1996 Acquisition, Pipeline, a Company subsidiary, acquired a 120-mile
gas transportation pipeline in southwestern Pennsylvania for an allocated  value
of $3.5 million. The Company regards this asset as non-strategic to its business
activities and is presently marketing the pipeline for sale.
 
COMPETITION AND MARKETS
 
    Competition  in all areas of the  Company's operations is intense. Major and
independent oil and gas  companies and oil and  gas syndicates actively bid  for
desirable  oil  and gas  properties,  as well  as  for the  equipment  and labor
required to  operate and  develop such  properties. A  number of  the  Company's
competitors   have   financial  resources   and  acquisition,   exploration  and
development budgets that are  substantially greater than  those of the  Company,
which  may  adversely  affect  the  Company's  ability  to  compete  with  these
companies. Many of  the Company's competitors  have been engaged  in the  energy
business  for a much longer time than the Company. Such companies may be able to
pay more for productive oil and gas properties and exploratory prospects and  to
define,  evaluate,  bid for  and  purchase a  greater  number of  properties and
prospects than the Company's financial or human resources permit. The  Company's
ability  to acquire additional properties and to discover reserves in the future
will be dependent on its ability to evaluate and select suitable properties  and
to consummate transactions in a highly competitive environment.
 
    The  market for  oil, gas  and natural gas  liquids produced  by the Company
depends on factors beyond its control, including domestic and foreign  political
conditions,  the overall level of supply of  and demand for oil, gas and natural
gas liquids, the price of imports of oil and gas, weather conditions, the  price
and  availability  of  alternative  fuels, the  proximity  and  capacity  of gas
pipelines and other transportation  facilities and overall economic  conditions.
The  oil and  gas industry  as a  whole also  competes with  other industries in
supplying the  energy  and  fuel  requirements  of  industrial,  commercial  and
individual consumers.
 
REGULATION
 
    The Company's oil and gas exploration, production and related operations are
subject  to extensive  rules and regulations  promulgated by  federal, state and
local agencies. Failure to comply with such rules and regulations can result  in
substantial  penalties.  The  regulatory  burden on  the  oil  and  gas industry
increases the Company's cost  of doing business  and affects its  profitability.
Because  such rules and regulations are frequently amended or reinterpreted, the
Company is unable to predict  the future cost or  impact of complying with  such
laws.
 
    The  State  of Texas  and  many other  states  require permits  for drilling
operations, drilling bonds  and reports concerning  operations and impose  other
requirements  relating to  the exploration and  production of oil  and gas. Such
states also  have  statutes  or  regulations  addressing  conservation  matters,
including  provisions for the unitization or  pooling of oil and gas properties,
the establishment of maximum rates of production from oil and gas wells and  the
regulation  of spacing, plugging and abandonment of such wells. The statutes and
regulations of  certain states  limit  the rate  at which  oil  and gas  can  be
produced from the Company's properties.
 
    FERC  regulates  interstate  natural gas  transportation  rates  and service
conditions, which affect the marketing of  gas produced by the Company, as  well
as  the revenues received by the Company for sales of such production. Since the
mid-1980s, the FERC  has issued a  series of orders,  culminating in Order  Nos.
636,  636-A  and  636-B  ("Order  636"),  that  have  significantly  altered the
marketing  and  transportation  of  gas.   Order  636  mandates  a   fundamental
restructuring of interstate pipeline sales and transportation service, including
the unbundling by interstate pipelines of the sales, transportation, storage and
other  components  of the  city-gate  sales services  such  pipelines previously
performed. One  of the  FERC's purposes  in issuing  the orders  is to  increase
competition within all phases of the gas industry. Order 636 and subsequent FERC
orders  on rehearing have been appealed and are pending judicial review. Because
these orders may  be modified as  a result of  the appeals, it  is difficult  to
predict  the ultimate impact of the orders  on the Company and its gas marketing
efforts. Generally,
 
                                       43
<PAGE>
Order 636  has eliminated  or substantially  reduced the  interstate  pipelines'
traditional  role as wholesalers of natural gas, and has substantially increased
competition and volatility in natural gas markets. While significant  regulatory
uncertainty  remains, Order 636 may ultimately  enhance the Company's ability to
market and  transport its  gas, although  it  may also  subject the  Company  to
greater  competition and the more  restrictive pipeline imbalance tolerances and
greater associated penalties for violation of such tolerances.
 
   
    Sales of oil and natural  gas liquids by the  Company are not regulated  and
are made at market prices. The price the Company receives from the sale of these
products  is  affected  by the  cost  of  transporting the  products  to market.
Effective as of January 1,  1995, the FERC implemented regulations  establishing
an indexing system for transportation rates for oil pipelines, which, generally,
would  index  such  rates  to  inflation,  subject  to  certain  conditions  and
limitations. These regulations could increase  the cost of transporting oil  and
natural  gas liquids by pipeline, although  the most recent adjustment generally
decreased rates. These regulations are subject to pending petitions for judicial
review. The Company is not able to  predict with certainty what effect, if  any,
these  regulations  will  have  on  it,  but,  other  factors  being  equal, the
regulations may,  over time,  tend to  increase transportation  costs or  reduce
wellhead prices for oil and natural gas liquids.
    
 
ENVIRONMENTAL MATTERS
 
    Operations  of the Company  are subject to  numerous and constantly changing
federal, state  and  local  laws  and regulations  governing  the  discharge  of
materials   into  the   environment  or  otherwise   relating  to  environmental
protection. These laws and  regulations may require  the acquisition of  certain
permits,  restrict  or  prohibit  the  types,  quantities  and  concentration of
substances that can be released into the environment in connection with drilling
and production,  restrict  or prohibit  drilling  activities that  could  impact
wetlands,  endangered or threatened species or other protected natural resources
and impose substantial  liabilities for pollution  resulting from the  Company's
operations.  Such laws  and regulations may  substantially increase  the cost of
exploring for, developing or producing oil and gas and may prevent or delay  the
commencement or continuation of a given project. In the opinion of the Company's
management,  the Company  is in  substantial compliance  with current applicable
environmental laws and regulations,  and the cost of  compliance with such  laws
and  regulations has not been material and is not expected to be material during
the next fiscal year. Nevertheless,  changes in existing environmental laws  and
regulations or in interpretations thereof could have a significant impact on the
operating  costs of the Company, as well as the oil and gas industry in general.
For instance, legislation has been proposed  in Congress from time to time  that
would  reclassify certain oil  and gas production  wastes as "hazardous wastes,"
which reclassification would make exploration  and production wastes subject  to
much   more  stringent  handling,  disposal  and  clean-up  requirements.  State
initiatives to further regulate the disposal of oil and gas wastes and naturally
occurring radioactive materials  are also pending  in certain states,  including
Texas, and these various initiatives could have a similar impact on the Company.
 
   
    The  Comprehensive Environmental  Response, Compensation,  and Liability Act
("CERCLA"), also known as the "Superfund" law, imposes liability, without regard
to fault or the legality of the original conduct, on certain classes of  persons
that  are  considered  to  have  contributed  to  the  release  of  a "hazardous
substance" into the environment. These persons include the owner or operator  of
the  disposal site  or the  site where the  release occurred  and companies that
disposed or arranged for the disposal  of the hazardous substances found at  the
site.  Persons who are or were  responsible for releases of hazardous substances
found at  the site  and persons  who are  or were  responsible for  releases  of
hazardous  substances under CERCLA may be subject to joint and several liability
for the costs of  cleaning up the hazardous  substances that have been  released
into  the  environment and  for  damages to  natural  resources, and  it  is not
uncommon for neighboring landowners and other  third parties to file claims  for
personal injury and property damage allegedly caused by the hazardous substances
released  into  the environment.  The Company  is able  to control  directly the
operation of  only those  wells with  respect  to which  its acts  as  operator.
Notwithstanding the Company's lack of
    
 
                                       44
<PAGE>
control  over wells operated  by others, the  failure of the  operator to comply
with applicable  environmental regulations  may,  in certain  circumstances,  be
attributed  to the Company. The Company  has no material commitments for capital
expenditures to comply with existing environmental requirements.
 
EMPLOYEES
 
    At June  30, 1996,  the Company  had 109  full-time employees.  None of  the
Company's employees is subject to a collective bargaining agreement. The Company
considers its relations with its employees to be good.
 
LEGAL PROCEEDINGS
 
    The Company is a defendant or codefendant in minor lawsuits that have arisen
in  the ordinary  course of  business. While the  outcome of  the these lawsuits
cannot be predicted with certainty, management  does not expect any of these  to
have a material adverse effect on the Company's consolidated financial condition
or results of operations.
 
TITLE TO PROPERTIES
 
    The  Company  has  obtained  title  opinions  on  substantially  all  of its
producing properties  and  believes  that  it has  satisfactory  title  to  such
properties  in accordance with  standards generally accepted in  the oil and gas
industry. As is customary in  the oil and gas  industry, the Company performs  a
minimal  title investigation  before acquiring  undeveloped properties.  A title
opinion is obtained  prior to the  commencement of drilling  operations on  such
properties. The Company's properties are subject to customary royalty interests,
liens  incident  to  operating agreements,  liens  for current  taxes  and other
burdens which the Company believes do  not materially interfere with the use  of
or  affect the value of such properties.  Substantially all of the Company's oil
and gas  properties  are mortgaged  to  secure borrowings  under  the  Company's
Existing  Debt Facility and  will continue to be  mortgaged to secure borrowings
under  the  Credit  Facility.  See  "Management's  Discussion  and  Analysis  of
Financial  Conditions  and  Results  of  Operations  --  Liquidity  and  Capital
Resources," and "Description of Other Indebtedness."
 
OPERATIONAL HAZARDS AND INSURANCE
 
    The Company's operations are  subject to the hazards  and risks inherent  in
drilling  and production  and transportation  of oil  and gas,  including fires,
natural disasters, explosions, encountering formations with abnormal  pressures,
blowouts,  cratering, pipeline ruptures, and spills,  any of which can result in
loss of hydrocarbons, environmental pollution, personal injury or loss of  life,
severe  damage to and destruction  of properties of the  Company and others, and
suspension of operations. See "Risk Factors -- Drilling Risks" and "Risk Factors
- -- Operating Hazards and Uninsured Risks."
 
   
    The Company maintains insurance  of various types  to cover its  operations.
The limits provided under its liability policies total $21 million. In addition,
the Company maintains operator's extra expense coverage which provides for care,
custody  and control of all  material wells drilled by  the Company as operator.
The Company believes that its insurance is adequate and customary for  companies
of  a similar size  engaged in operations  similar to those  of the Company, but
losses could occur for uninsurable or uninsured risks or in amounts in excess of
existing insurance  coverage. The  Company's general  policy is  to only  engage
drilling  contractors who  provide substantial  insurance coverage  and name the
Company as an additional named insured. The occurrence of a significant  adverse
event,  the risks  of which  are not  fully covered  by insurance,  could have a
material adverse  effect on  the Company's  financial condition  and results  of
operations.  Moreover, no assurances can be given  that the Company will be able
to maintain adequate insurance in the future at rates it considers reasonable.
    
 
                                       45
<PAGE>
                                   MANAGEMENT
 
    The  executive officers and directors of the Company following completion of
the Corporate Reorganization are  listed below, together  with a description  of
their experience and certain other information (ages provided are as of June 30,
1996).  Each of the directors serve for  a one year term. Executive officers are
appointed by the Board of Directors.
 
<TABLE>
<CAPTION>
NAME                             AGE       EMPLOYED SINCE                        POSITION WITH COMPANY
- ---------------------------      ---      -----------------  --------------------------------------------------------------
<S>                          <C>          <C>                <C>
Cadell S. Liedtke                    41            1988      Chairman of the Board, Chief Executive Officer and Director
Michael J. Grella                    47            1988      President, Chief Operating Officer and Director
Henry G. Musselman                   42            1992      Executive Vice President and Director
Jerry J. Langdon                     43             n/a      Director
W.D. Kennedy                         76             n/a      Director
Bobby W. Page                        53            1996      Senior Vice President, Treasurer and Chief Financial Officer
Clifford N. Hair, Jr.                49            1992      Vice President -- Land and Secretary
Roger J. Wetz                        47            1992      Vice President -- Exploration (Geology)
Roger A. Freidline                   46            1993      Vice President -- Exploration (Geophysics)
Brian K. Miller                      36            1992      Vice President -- Reservoir Engineering
Sal J. Pagano                        45            1995      Vice President -- Engineering and Operations
Keith Atwood                         42            1992      Vice President -- Field Operations
Celia A. Zinn                        48            1996      Controller
</TABLE>
 
    Cadell S. Liedtke entered the oil and gas business in Midland, Texas in 1977
as an independent landman generating oil and gas prospects in the Permian Basin.
He founded the  Company's predecessor  with Michael J.  Grella in  1988 and  has
served  as managing partner and/or chief  executive officer since that time. Mr.
Liedtke has served  on the  Board of  Directors of  Texas Commerce  Bank-Permian
Basin and has been appointed by Texas Governor George W. Bush to the Oil and Gas
Compact  Commission. Mr.  Liedtke is  a member  of the  All-American Wildcatters
Association, the Permian Basin Petroleum Association, the Permian Basin Landmans
Association and the Independent Producer's  Association of America. Mr.  Liedtke
graduated  from the University of Texas at Austin  in 1977 with a B.A. degree in
economics.
 
   
    Michael J. Grella has served as  Chief Operating Officer of the Company  and
its predecessor entities since their formation in 1988. He owned and operated an
independent  oil and gas  company and has  invested in the  oil and gas business
since 1982. Mr. Grella is a  member of the Permian Basin Petroleum  Association,
the  Independent  Producer's  Association  of  America,  the  Texas  Independent
Producers  and  Royalty  Owners  Association  and  the  Permian  Basin   Landman
Association.  Mr.  Grella  has  a  B.S.  degree  in  computer  science  from the
University of California.
    
 
   
    Henry G.  Musselman began  his oil  and gas  career in  1975 with  Musselman
Petroleum  and Land  Company where  he served as  Vice President  and a Director
until forming Musselman, Owen & King in 1982. For the 10 years until merging his
company into  Costilla's  predecessor  in  1992,  Mr.  Musselman  developed  and
acquired oil and gas properties throughout the Permian Basin. Mr. Musselman is a
member and former director of the Independent Producer's Association of America.
Mr.  Musselman graduated from the  University of Texas at  Austin in 1975 with a
B.B.A. degree.
    
 
    Jerry J. Langdon has previously held positions with WP Corporation,  Houston
Pipeline  Company, Texas  Oil &  Gas Corporation  and W.  Wilson Corporation. In
1980, Mr. Langdon formed  Texas IntraMark Gas Company,  Inc., an intrastate  gas
gathering company engaging in the business of constructing and operating natural
gas  gathering, treating and processing facilities.  In 1984, Mr. Langdon formed
Langdon  &  Associates,  a  natural  gas  consulting  group  advising  petroleum
resource-oriented
 
                                       46
<PAGE>
companies,  financial  institutions and  law firms  on  a variety  of technical,
commercial and regulatory  issues. Mr. Langdon  served as a  member of the  FERC
from  1988 to June 1993. Since leaving the FERC, Mr. Langdon formed Republic Gas
Corp. to  acquire,  construct  and  operate  intrastate  natural  gas  pipeline,
gathering,  processing, treating  and marketing  facilities. Mr.  Langdon is the
President of  both Republic  and the  Midla  Companies. Mr.  Langdon is  a  1975
graduate of the University of Texas at Austin with a B.S. degree.
 
    W.  D. Kennedy  has been  continually involved in  the oil  and gas business
since 1948.  From 1953  until 1980,  Mr. Kennedy  was an  executive officer  and
director  of C&K Petroleum, Inc., and its predecessor. C&K Petroleum, Inc. was a
publicly held corporation from 1971 until 1980, when the company was sold for in
excess of $200 million. Mr.  Kennedy remains an active  investor in the oil  and
gas business. Mr. Kennedy is a graduate of the University of Texas, and a member
of  the All-American  Wildcatters Association, a  past president  of the Permian
Basin Petroleum Association, a  former director of  the Texas Mid-Continent  Oil
and Gas Association, and an advisory director of Norwest Bank Texas, Midland.
 
    Bobby W. Page began his oil and gas career with MGF Oil Corporation in 1967,
where  he remained until  1988, ultimately serving  as Executive Vice President,
Chief Financial Officer and  a member of the  Board of Directors. Following  two
years  as  a self-employed  financial consultant,  Mr.  Page joined  Alta Energy
Corporation in 1990 as Executive  Vice President, Treasurer and Chief  Financial
Officer.  From July  1993 until  joining the  Company, Mr.  Page served  as Vice
President, Chief Financial Officer and Secretary of Marcum Natural Gas Services,
Inc. Mr. Page graduated from the University of Oklahoma with a B.B.A. degree  in
accounting in 1965.
 
    Clifford  N. Hair, Jr. has served in district and division landman roles, as
well as a corporate officer with Texas Gas Exploration Corporation, Samedan  Oil
Corporation, Henry Petroleum Corporation and Donald C. Slawson Oil Producer. For
the  two year  period prior  to joining  the Company  in 1992,  Mr. Hair  was an
independent landman involved  in drilling  projects in Texas  and Oklahoma.  Mr.
Hair is a Certified Petroleum Landman's and a member of the American Association
of  Petroleum  Landmen and  the Petroleum  Basin  Landman Association.  Mr. Hair
graduated with  honors from  the University  of Houston  in 1971  with a  B.B.A.
degree in accounting.
 
    Roger J. Wetz began his oil and gas career with IMCO Services, a division of
Halliburton,  Inc. in 1974. He held a  variety of geological positions with Gulf
Energy & Minerals Company, TXO Production Corporation and Terra Resources,  Inc.
from  1976 to 1989. From 1989 until joining the Company in 1992, Mr. Wetz was an
independent geologist  generating  prospects  in the  Permian  Basin.  Mr.  Wetz
graduated from St. Mary's University in 1973 with a B.S. degree in geology.
 
    Roger  A.  Freidline began  his industry  career with  Union Oil  Company of
California. From 1976 until  1985, Mr. Freidline  served in various  geophysical
capacities  with Forest  Oil Corporation,  Gifford, Mitchell  and Wisenbaker and
Heritage Resources, Inc. Mr. Freidline was an independent geophysicist from 1985
until joining  the  Company, except  for  a  period of  employment  as  district
geologist  for Hondo  Oil & Gas  Company prior to  its sale. Mr.  Freidline is a
Certified Petroleum  Geologist,  and a  member  of the  Society  of  Exploration
Geophysicists,  the  Permian  Basin  Geophysical  Society  and  the  West  Texas
Geological Society. He has co-authored papers which have appeared in Geology and
The Bulletin of the Seismological Society  of America. Mr. Freidline received  a
B.S.  degree with  highest honors  from the New  Mexico Institute  of Mining and
Technology in  1972 and  a Masters  of  Science degree  in geophysics  from  the
University of Utah in 1974.
 
    Brian  K. Miller entered the oil and  gas business as an operations engineer
for ARCO Oil and  Gas Company. From  1984 to 1987, he  was a reservoir  engineer
with  First City  National Bank of  Midland, Texas,  and from 1987  to 1989, Mr.
Miller was an independent consulting engineer.  Prior to joining the Company  in
1992,  Mr. Miller  served as  an oil  and gas  analyst under  appointment to the
Federal Deposit Insurance Corporation. Mr. Miller is a member of the Society  of
Petroleum Engineers.
 
                                       47
<PAGE>
Mr.  Miller received a B.S. degree  with highest honors in petroleum engineering
from the  University  of Texas  at  Austin in  1982  and a  Master  of  Business
Administration degree with honors in finance in 1984.
 
    Sal  J. Pagano began  his oil and  gas career with  Amoco Production Company
where he  was  employed until  1978.  From 1978  through  1989, Mr.  Pagano  was
employed  by several independent  oil and gas  companies in Midland,  Texas in a
variety of petroleum  engineering capacities.  Prior to joining  the Company  in
1995,  Mr. Pagano was employed by Midland  Resources Company from 1989 as a vice
president. Mr. Pagano  is a registered  petroleum engineer and  a member of  the
Society of Petroleum Engineers. Mr. Pagano graduated in 1973 from the University
of Missouri at Rolla with a B.S. degree in petroleum engineering.
 
    Keith  Atwood began his  oil and gas  career with Otis  Engineering Corp. in
1974. Mr. Atwood worked as an independent  consultant from 1979 to 1983 when  he
joined  Musselman,  Owen &  King Operating  Co. to  manage field  operations. He
served in that capacity until joining  the Company in 1992. Mr. Atwood  attended
Southwest Texas State University and the University of Texas.
 
    Celia  A. Zinn joined the Company in  1996. From 1992 to 1996, she practiced
public accounting in Midland. Ms.  Zinn has 18 years  experience in the oil  and
gas  industry, including  12 years as  Controller for Clayton  W. Williams, Jr.,
Inc. from 1981  to 1992. Ms.  Zinn is  a certified public  accountant. Ms.  Zinn
graduated  from  the  University  of  Texas-Arlington in  1978  with  a  B.A. in
mathematics.
 
                                       48
<PAGE>
                    SECURITY OWNERSHIP OF CERTAIN BENEFICIAL
                             OWNERS AND MANAGEMENT
 
   
    The following  table sets  forth the  names  and addresses  of each  of  the
Company's  stockholders  who  beneficially own  more  than five  percent  of the
Company's Common  Stock,  the  number  of  shares  beneficially  owned  by  such
shareholders  and the percentage of the Common  Stock so owned at June 30, 1996,
assuming in each case the Corporate Reorganization had been consummated at  June
30,  1996  and  that  the  Common  Stock  Offering  is  consummated  without the
underwriters' over-allotment option being exercised.
    
 
   
<TABLE>
<CAPTION>
                                         AMOUNT AND NATURE OF
                                         BENEFICIAL OWNERSHIP    PERCENT OF
NAME AND ADDRESS OF BENEFICIAL OWNER             (1)                CLASS
- --------------------------------------  ----------------------  -------------
<S>                                     <C>                     <C>
Cadell S. Liedtke ....................          2,656,796             26.6%
400 W. Illinois
Midland, Texas 79701
Michael J. Grella ....................          1,558,161             15.6%
400 W. Illinois
Midland, Texas 79701
NationsBanc Capital Corp. ............          1,080,008             10.8%
100 North Tryon Street
Charlotte, North Carolina 28255
Henry G. Musselman ...................            705,035              7.0%
400 W. Illinois
Midland, Texas 79701
</TABLE>
    
 
- ------------------------------
   
(1)  All persons own the listed shares of record.
    
 
   
    The following table sets forth information as of June 30, 1996 (assuming the
Corporate Reorganization had been consummated on such date) with respect to  the
shares  of Common Stock  beneficially owned by each  of the Company's Directors,
the Chief  Executive  Officer  and  the  three  other  most  highly  compensated
executive  officers for 1996 (whose annualized  compensation for such year based
on compensation levels following  the Offering is  expected to exceed  $100,000)
and  all Directors  and executive  officers as  a group  and the  percent of the
outstanding Common Stock owned by each, assuming that the Common Stock  Offering
is consummated without the underwriters' over-allotment option being exercised.
    
 
   
<TABLE>
<CAPTION>
DIRECTORS AND NAMED                      AMOUNT AND NATURE OF    PERCENT OF
EXECUTIVE OFFICER                        BENEFICIAL OWNERSHIP     CLASS (1)
- --------------------------------------  ----------------------  -------------
<S>                                     <C>                     <C>
Cadell S. Liedtke.....................          2,656,796             26.6%
Michael J. Grella.....................          1,558,161             15.6%
Henry G. Musselman....................            705,035              7.0%
Bobby W. Page.........................             75,000(2)           0.7%
All Officers and Directors as a group
(13 persons)..........................          5,554,992(3)          52.2%
</TABLE>
    
 
- ------------------------------
(1)  For  the sole purpose  of calculating these  percentages, the shares, which
     the named person has the  right to acquire within  60 days, by exercise  of
     the  options described  in these  footnotes, are  deemed outstanding shares
     with respect to that person's percentage ownership and with respect to  the
     percentage ownership of all Officers and Directors as a group.
 
   
(2)  Includes  75,000 shares  issuable pursuant to  an option  granted under the
     Company's  1996  Stock  Option  Plan  which  option  will  be   immediately
     exercisable  upon closing of the Offerings at  a price equal to the initial
     public offering price of the Common Stock.
    
 
   
(3)  Includes 635,000  shares issuable  pursuant to  options granted  under  the
     Company's  1996  Stock  Option  Plan  which  options  will  be  immediately
     exercisable upon closing of the Offerings  at a price equal to the  initial
     public offering price of the Common Stock.
    
 
                                       49
<PAGE>
                  EXECUTIVE COMPENSATION AND OTHER INFORMATION
 
SUMMARY COMPENSATION TABLE
 
    The following table sets forth information for the Company's Chief Executive
Officer  and the  three other most  highly compensated  executive officers whose
annual compensation for the fiscal year ending December 31, 1996 is expected  to
exceed  $100,000.  Information  is  presented  for  1995,  and  for  1996  on an
annualized basis based on salaries to be effective following consummation of the
Offerings. Information for  1994 and  prior years  is not  comparable since  the
Company's  predecessor was a general partnership  in which the partners received
periodic partnership distributions in lieu of salary.
 
<TABLE>
<CAPTION>
                                                                                      LONG-TERM
                                                                                    COMPENSATION
                                                                                       AWARDS
                                                                                    -------------
                                                ANNUAL COMPENSATION                  SECURITIES
                                 -------------------------------------------------   UNDERLYING
                                                                    OTHER ANNUAL      OPTIONS/        ALL OTHER
NAME AND PRINCIPAL POSITION        YEAR     SALARY($)  BONUS($)   COMPENSATION($)    SARS(#)(2)    COMPENSATION($)
- -------------------------------  ---------  ---------  ---------  ----------------  -------------  ----------------
<S>                              <C>        <C>        <C>        <C>               <C>            <C>
Cadell S. Liedtke
  Chairman of the Board and           1995    185,700         --             --              --               --
   Chief Executive Officer            1996    300,000         --             --              --               --
Michael J. Grella
  President and Chief Operating       1995    261,750         --             --              --               --
   Officer                            1996    300,000         --             --              --               --
Henry G. Musselman
                                      1995    139,800         --             --              --               --
  Executive Vice President            1996    215,000         --             --              --               --
Bobby W. Page
  Senior Vice President,
   Treasurer and Chief                1995(1)        --        --            --              --               --
   Financial Officer                  1996    150,000         --             --          75,000               --
</TABLE>
 
- ------------------------------
(1)  Mr. Page joined the Company in June 1996.
 
(2)  The amount shown represents the number of shares subject to a stock  option
     to  be granted upon the closing of  the Offerings pursuant to the Company's
     1996 Stock Option  Plan described  under "--  Benefit Plans  -- 1996  Stock
     Option  Plan." The option will be granted  with an exercise price per share
     equal to the initial public offering price of the Common Stock and will  be
     granted for a 10-year term.
 
DIRECTORS' COMPENSATION
 
    Compensation  for non-employee directors (Messrs.  Langdon and Kennedy) will
consist of an annual retainer fee of  $10,000, plus a $1,000 fee for each  Board
meeting  attended and a $1,000  fee for attending a  committee meeting held on a
day other than the same day of  a Board meeting. In addition, outside  Directors
are  participants in the Company's Outside Directors Stock Option Plan described
under "--  Benefit  Plans --  Outside  Directors Stock  Option  Plan."  Employee
Directors  do not receive compensation  for serving on the  Board or the Board's
committees.
 
EMPLOYMENT AGREEMENTS
 
   
    Messrs.  Liedtke,  Grella  and   Musselman  have  entered  into   employment
agreements  (the "Founders Employment  Agreements") with the  Company which will
become effective upon the closing of the Offerings and replace certain  existing
agreements.  The  Founders  Employment  Agreements  are  each  for  three years,
commencing on the closing of the Offerings and each will automatically renew for
successive one-year periods thereafter  unless the employee  is notified to  the
contrary.  The  Founders Employment  Agreements  provide for  salary  levels for
Messrs. Liedtke,  Grella  and  Musselman of  $300,000,  $300,000  and  $215,000,
respectively.
    
 
    Each  of Messrs. Liedtke, Grella and  Musselman would receive his salary for
the remaining  term  of the  applicable  Founders Employment  Agreement  if  the
Company were to terminate such person's
 
                                       50
<PAGE>
   
employment  other than for cause.  If such person were  to voluntarily leave his
employment with the Company prior to the second anniversary of the Agreement  no
further  payments would  be required. If  a voluntary termination  were to occur
after the second anniversary of the Agreement, such person would be entitled  to
one  year's  salary  from  the date  of  termination.  Each  Founders Employment
Agreement provides that the covered employee  will not compete with the  Company
for  a  one  year period  following  his  voluntary cessation  of  employment or
termination of employment for cause, in either case if such event occurs  within
the initial three-year term of the Agreement. Competitive activities are defined
as engaging in the oil and gas business in any area in which the Company is then
active.
    
 
    Bobby W. Page has entered into an employment agreement (the "Page Employment
Agreement")  with  the  Company effective  June  30, 1996.  The  Page Employment
Agreement is  for  a  period  of  three  years  from  June  30,  1996  and  will
automatically  renew for successive one-year  periods thereafter unless Mr. Page
is notified  to the  contrary  by the  Company.  The Page  Employment  Agreement
provides  a $25,000 bonus (which includes Mr. Page's cost of relocation), plus a
base salary of $150,000 until January  1, 1997; $175,000 until January 1,  1998;
and  $185,000 thereafter. In addition, Mr. Page will receive options to purchase
75,000 shares of  Common Stock,  certain insurance benefits  and other  benefits
generally  available  to the  Company's employees.  Mr.  Page would  receive his
salary for the remaining  term of the Page  Employment Agreement if the  Company
were  to terminate the Page Employment  Agreement other than for cause. However,
if Mr.  Page were  to voluntarily  leave  his employment  with the  Company,  no
further payments would be required.
 
BENEFIT PLANS
 
   
    OUTSIDE  DIRECTORS STOCK  OPTION PLAN.   The Outside  Directors Stock Option
Plan provides for the issuance of stock options to the outside directors of  the
Company.  A  total of  50,000 shares  of  Common Stock  has been  authorized and
reserved for issuance under the plan, subject to adjustments to reflect  changes
in the Company's capitalization resulting from stock splits, stock dividends and
similar  events. Only outside directors are eligible to participate in the plan.
Outside directors  are those  directors of  the Company  who are  not  executive
officers  or regular salaried employees of the  Company as of the date an option
is granted. Under the plan, an option  for 1,000 shares of Common Stock will  be
granted  to each person who qualifies as an outside director each year that such
person is elected  as a  director of  the Company.  The exercise  price of  each
option  granted under the plan will be the fair market value (as reported on the
Nasdaq National Market) of the Common Stock  at the time the option is  granted,
and  may be  paid either in  cash, shares  of Common Stock  or a broker-assisted
cashless transaction.  Each option  will be  exercisable immediately,  and  will
expire ten years from the date of grant. An option granted under the plan is not
transferrable other than by will or the laws of descent and distribution. In the
event  a participant in the plan ceases to be an outside director, other than by
reason of  death or  change of  control  of the  Company, such  participant  may
exercise  an outstanding  option under  the plan  within ninety  days after such
termination, to the extent the participant  was entitled to exercise the  option
on the date of termination. In the event of the death of a participant under the
plan,  such  participant's  option(s)  may  be  exercised  by  the  executors or
administrators of the optionee's estate or  by the legatees of such  participant
within  one year  after his death,  so long  as the term  of the  option has not
expired. The  Company does  not  receive any  consideration  upon the  grant  of
options  under the plan. The  options granted under the  plan are intended to be
non-qualifying options for  federal income tax  purposes. Because options  under
the  plan are  not generally  transferrable, do  not appear  to be  subject to a
substantial risk of forfeiture  and the exercise price  will be the fair  market
value  of the  common stock  on the  date of  grant, the  options should  not be
taxable to an optionee  until the optionee exercises  the option, at which  time
the optionee would recognize income on the difference between the exercise price
and  the fair market value of  the shares on the date  of exercise. The grant of
options under the plan should be treated as compensation paid by the Company for
purposes of  the  Company's federal  income  tax considerations.  The  Board  of
Directors  may amend the  plan without the  approval of the  stockholders of the
Company in any respect other than any
    
 
                                       51
<PAGE>
   
amendment which requires  stockholder approval  by law  and may  only modify  an
outstanding option, including the repricing of such options, with the consent of
the  option holder. The  Company currently has  five directors, two  of whom are
eligible to participate in the plan.
    
 
   
    1996 STOCK OPTION PLAN.  The 1996  Stock Option Plan provides for the  grant
of  both incentive  stock options and  non-qualifying stock options,  as well as
limited stock appreciation rights and supplemental bonuses, to the employees  of
the  Company  and its  subsidiaries, including  officers  and directors  who are
salaried employees.  A  total  of  850,000  shares  of  Common  Stock  has  been
authorized  and reserved for  issuance under the plan,  subject to adjustment to
reflect changes in  the Company's  capitalization resulting  from stock  splits,
stock  dividends and similar  events. The plan  is administered by  the Board of
Directors. The Board of Directors has the sole authority to interpret the  plan,
to determine the persons to whom options will be granted, to determine the basis
upon  which the options  will be granted,  and to determine  the exercise price,
duration and other terms of the options  to be granted under the plan;  provided
that  (a) the exercise  price of each option  granted under the  plan may not be
less than the fair market  value of the Common Stock  on the date the option  is
granted  (and for  incentive stock  options, 110%  of fair  market value  if the
employee is  the  beneficial  owner of  10%  or  more of  the  Company's  voting
securities),  (b)  the exercise  price  must be  paid  in cash,  by surrendering
previously owned shares of Common Stock upon the exercise of the option or by  a
promissory  note or broker-assisted  cashless exercise approved  by the Board of
Directors, (c) the  term of  the option  may not exceed  ten years,  and (d)  no
option  is  transferrable  other  than  by  will  or  the  laws  of  descent and
distribution. Upon termination of an optionee's employment (other than by  death
or  disability),  an  incentive  stock  option may  be  exercised  prior  to the
expiration date of  the option or  within three  months after the  date of  such
termination,  whichever is earlier, but only to  the extent the optionee had the
right to exercise the option upon the date of such termination, while the rights
of the holder of a non-qualifying stock option will be set forth in each  option
agreement.  In the  event of the  disability of  an optionee, the  option may be
exercised by such person, his personal  representative at any time, but only  to
the  extent the optionee had the right to  exercise the option as of the date of
his disability.  In the  event  of death  of the  optionee,  the option  may  be
exercised  by his personal  representative or successor in  interest at any time
prior to the expiration of the option  to the extent the option was  exercisable
at  the time of the optionee's death. Incentive stock options may not be granted
under the plan to any individual if  the effect of such grant would permit  that
person  to have the first opportunity to  exercise such options, in any calendar
year, for the  purchase of shares  having a fair  market value (at  the time  of
grant  of the option) in excess of $100,000.  Neither the Company nor any of its
subsidiaries will receive any  consideration for the  granting of options  under
the  plan. Limited stock appreciation rights may  be granted under the plan with
respect to specified options,  allowing the option holder  to receive, in  cash,
the difference between the exercise price and the market value in the event of a
change  of  control  of the  Company.  The  Board of  Directors  may  also grant
supplemental bonuses under  the plan which  are cash bonuses  not to exceed  the
amount  of income tax liability incurred by a plan participant upon the exercise
of a non-qualifying  stock option  or a  limited stock  appreciation right  with
respect  to which the  bonus was granted. Incentive  stock options granted under
the plan are intended to have the federal income tax consequences of a qualified
stock option. As a result, the exercise of an incentive stock option will not be
a taxable event; the taxable event occurs at the time the shares of Common Stock
acquired upon exercise of the option are sold. If the optionee holds such shares
for the later of two years from the date the option was granted or one year from
the date of exercise of  the option, the difference  between the price paid  for
the  shares at exercise  and the price for  which those shares  are sold will be
treated as capital gains income.  If the optionee does  not hold the shares  for
the  required holding  period, the  income would  be treated  as ordinary income
rather than capital gains income. The non-qualifying stock options granted under
the plan should  be taxable  when the  option is  exercised, at  which time  the
optionee  would recognize  ordinary income  the difference  between the exercise
price and the fair market value of the shares on the date of exercise. The grant
of options under the  plan will be  treated as compensation  by the Company  for
federal  income tax purposes. The Board of Directors may amend the plan, without
stockholder  approval,   in  any   respect  other   than  any   amendment   that
    
 
                                       52
<PAGE>
   
requires  stockholder approval  by law,  and may  modify an  outstanding option,
including the  repricing of  non-qualifying  options, with  the consent  of  the
option holder. There are currently approximately 100 persons who are eligible to
participate under the plan.
    
 
   
    BONUS  INCENTIVE PLAN.  The Company has  adopted the Bonus Incentive Plan to
become effective upon the  completion of the Offerings.  The plan provides  that
the  Board of Directors  each year may  award bonuses in  cash, Common Stock, or
some combination thereof, to those  officers, directors, employees and  advisors
of  the  Company or  a subsidiary  of the  Company, who  the Board  of Directors
determines have contributed to  the success of the  Company. A total of  100,000
shares  of Common Stock has been authorized  and reserved for issuance under the
plan, subject to adjustments to reflect changes in the Company's  capitalization
resulting  from stock splits, stock dividends  and similar events. All officers,
directors, employees and advisors of the Company or a subsidiary of the  Company
who have completed a minimum of 180 days of service and are employed or retained
by  the Company or such subsidiary on the  last day of the plan year, other than
such persons who own  ten percent or  more of the  outstanding shares of  Common
Stock  during that year  are eligible to  participate in the  plan. Bonus awards
will be  determined based  on a  number of  factors, including  performance  and
salary level of the participant and the financial performance of the Company and
its  subsidiaries. Bonuses will be awarded after review and upon approval of the
Board of Directors, subject to the terms and conditions of the plan.
    
 
                              CERTAIN TRANSACTIONS
 
    A&P supplies meter  reading services  which measures gas  production to  the
Company,  as well as to unaffiliated oil  and gas companies. A&P is also engaged
in the sale  of gas meter  and regulating  equipment, and in  certain other  oil
field  related  businesses. For  the fiscal  year ended  December 31,  1995, the
Company accounted for approximately  27% of A&P's gross  revenues. From time  to
time,  the Company has  advanced funds to  A&P for working  capital needs. These
advances have been consolidated into two promissory notes. One note was executed
December 31, 1994 in the original  principal amount of $370,000. The note  bears
interest at a floating rate equal to the "prime rate" plus 1.0%. No principal or
interest  payments are due until the maturity  of the note at December 31, 2004.
The note is secured by a second lien on A&P's accounts receivable, inventory and
equipment. The second note is in  the original principal amount of $247,000  and
is  dated May 22, 1996. The note bears  interest at 6.0% per annum, is unsecured
and is payable upon demand. During the fiscal year ended December 31, 1995,  A&P
received $612,139 from the Company for meter reading, meter repair, calibration,
flow  line installation and other related  services provided to the Company. The
Company believes that the services and charges therefor are comparable to  those
the Company could have obtained from unaffiliated third parties.
 
   
    During 1995 the Company paid $440,884 to Valley for gas compression and salt
water  disposal  charges.  During 1995,  Valley  paid the  Company  $109,399 for
operating costs  of its  salt water  disposal wells  and gas  compressors.  Also
during  1995,  the  Company paid  CSL  $592,920  for management  fees  and lease
payments on equipment.
    
 
   
    During a portion of 1995, the Company leased office space from 511 Tex L.C.,
in which Messrs. Liedtke, Grella and Musselman are the sole members. The  amount
of  rental payments  to 511  Tex L.C.  during 1995  was $67,896.  The Company no
longer leases office space from any affiliated party.
    
 
    The Company  has  agreed that,  upon  the request  of  NBCC, on  up  to  two
occasions,  the  Company will  register  under the  Securities  Act of  1933, as
amended (the "Securities Act"), and applicable state securities laws the sale of
the Common Stock owned by NBCC.  The Company's obligation is subject to  certain
limitations regarding the timing of registrations and certain other matters. The
Company  is also  obligated to  offer to  NBCC and  Messrs. Liedtke,  Grella and
Musselman (collectively, the  "Affiliated Holders") the  opportunity to  include
shares  of the  Common Stock  owned by  them in  certain registration statements
filed by  the Company.  In addition,  the Company  has agreed  to indemnify  the
 
                                       53
<PAGE>
Affiliated   Holders  and  their  respective   officers  and  directors  against
securities law liabilities arising in connection with such offerings, other than
liabilities arising as a result of  information furnished to the Company by  the
Affiliated  Holders participating in the  registration. The Company is obligated
to  pay  all  expenses  incident  to  such  registration,  except  underwriters'
discounts  and commissions allocable to the sale of shares by Affiliated Holders
and any  professional  fees and  expenses  incurred by  the  Affiliated  Holders
incident to such registration. The Affiliated Holders have agreed that they will
not sell any shares of Common Stock for a period of 180 days after the Offerings
without the consent of Prudential Securities Incorporated.
 
    Certain   of  the  transactions   comprising  the  Corporate  Reorganization
represent transactions  between  the  Company,  or  its  predecessors,  and  its
affiliates.  Messrs. Liedtke, Grella  and Musselman, the  shareholders of Valley
and CSL will sell the stock of Valley  and the assets of CSL to the Company  for
$0.7  million.  The  purchase price  is  based on  negotiations  between Messrs.
Liedtke, Grella and Musselman, on the one hand, and NBCC, considering the  value
to  the Company of the stock and assets being acquired. No third party conducted
an appraisal of either Valley or CSL.
 
   
    Messrs. Liedtke, Grella and Musselman will receive an aggregate distribution
from the LLC of approximately $3.5 million which is estimated to be the  federal
income  tax  liability (as  well as  the  federal income  tax liability  on such
distribution) which will be owed by  Messrs. Liedtke, Grella and Musselman as  a
result  of the  Corporate Reorganization.  However, the  precise amount  of such
liability will be dependent upon a number of factors which cannot be  determined
with  certainty until subsequent  to December 31,  1996. While the  amount to be
distributed has been  determined in good  faith by the  Company's tax  advisors,
there  can  be no  assurance that  the actual  tax liability  of any  of Messrs.
Liedtke, Grella or Musselman  will not be less  or greater than the  distributed
amounts. If the distributed amounts exceed the ultimate tax liabilities, none of
such  persons will reimburse the Company.  Correspondingly, if the tax liability
exceeds the amount of such distributions, the Company will not make any  further
distributions to cover such short-fall. NBCC is also receiving a distribution of
$800,000  which  represents  its  post-redemption  ownership  percentage  of the
distribution made to Messrs. Liedtke, Grella and Musselman. However, NBCC has no
tax or other liability with respect  to such distribution. In addition,  Messrs.
Liedtke,  Grella and Musselman  and NBCC will receive  an aggregate of 6,000,000
shares of Common Stock in the Merger in exchange for their interests in the LLC.
    
 
                                       54
<PAGE>
                              DESCRIPTION OF NOTES
 
GENERAL
 
    The Notes will be issued pursuant to an Indenture (the "Indenture")  between
the Company and State Street Bank and Trust Company, as trustee (the "Trustee").
A  copy of the Indenture in substantially the  form in which it will be executed
has been  filed  as an  Exhibit  to the  Registration  Statement of  which  this
Prospectus  is  a part.  The  terms of  the Notes  include  those stated  in the
Indenture and  those  made part  of  the Indenture  by  reference to  the  Trust
Indenture  Act of 1939,  as amended (the  "Trust Indenture Act").  The Notes are
subject to all such terms,  and Holders of Notes  are referred to the  Indenture
and  the Trust Indenture Act  for a statement thereof.  The following summary of
certain provisions  of the  Indenture does  not purport  to be  complete and  is
qualified  in  its  entirety  by  reference  to  the  Indenture,  including  the
definitions therein of certain terms used below and those terms that are made  a
part  of the Indenture by reference to  the Trust Indenture Act. The definitions
of certain terms used  in the following  summary are set  forth below under  the
caption "Certain Definitions."
 
    As of the date of the Indenture, Costilla Redeco Energy, L.L.C. and Costilla
Redeco  Operating,  L.L.C.,  through  which the  Company  conducts  its Moldovan
operations,  will   be  Unrestricted   Subsidiaries.  However,   under   certain
circumstances,  the Company will be able to designate additional Subsidiaries as
Unrestricted Subsidiaries.  If  so designated,  such  Subsidiaries will  not  be
subject to many of the restrictive covenants set forth in the Indenture. As used
herein,  "Subsidiary" refers  to any  Subsidiary of the  Company that  is not an
Unrestricted Subsidiary.
 
PRINCIPAL, MATURITY AND INTEREST
 
    The Notes will be unsecured  senior subordinated general obligations of  the
Company,  limited in aggregate principal amount  to $100 million and will mature
on                    ,  2006. Interest on the Notes will accrue at the rate  of
   %  per annum and will  be payable semiannually in  arrears on             and
          commencing on           1997, to Holders of record on the  immediately
preceding            and            . Interest on the Notes will accrue from the
most recent date to  which interest has  been paid or, if  no interest has  been
paid, from           , 1996. Interest will be computed on the basis of a 360-day
year comprised of twelve 30-day months. Principal, premium, if any, and interest
on  the Notes will be payable at the  office or agency of the Company maintained
for such purpose within the City and State of New York or, at the option of  the
Company,  payment of interest may be made by  check mailed to the Holders of the
Notes at their  respective addresses  set forth in  the register  of Holders  of
Notes;  PROVIDED that all payments with respect to Global Notes and Certificated
Securities the Holders  of which have  given wire transfer  instructions to  the
Company  will be required to  be made by wire  transfer of immediately available
funds to  the  accounts  specified  by  the  Holders  thereof.  Until  otherwise
designated by the Company, the Company's office or agency in New York will be in
the  office of the Trustee maintained for such purpose. The Notes will be issued
in denominations of $1,000 and integral multiples thereof.
 
SUBORDINATION
 
   
    The payment of principal of, premium, if any, and interest on the Notes  and
the  Subsidiary Guarantees thereof will be  subordinated in right of payment, as
set forth in the Indenture and  the Subsidiary Guarantees, to the prior  payment
in  full of  Senior Indebtedness and  Guarantor Senior  Indebtedness, which will
include  borrowings  under  the  Credit  Facility  and  the  guarantees  thereof
delivered  by any Subsidiary Guarantors, whether  outstanding on the date of the
Indenture or thereafter incurred. As of the date of the Indenture, there will be
no  Subsidiary  Guarantors.  As  a  result,  claims  of  creditors  against  the
Subsidiaries  and the Unrestricted Subsidiaries  including their trade creditors
and tort claimants, will effectively have priority to the property and  earnings
of  such Subsidiaries  over claims  of creditors  of the  Company, including the
Holders.
    
 
    Upon any  distribution to  creditors  of the  Company  in a  liquidation  or
dissolution  of  the Company  or  in a  bankruptcy,  reorganization, insolvency,
receivership or similar proceeding relating to the
 
                                       55
<PAGE>
Company or  its property,  an assignment  for the  benefit of  creditors or  any
marshaling  of  the  Company's assets  and  liabilities, the  holders  of Senior
Indebtedness will  be  entitled  to receive  payment  in  full in  cash  of  all
Obligations due in respect of such Senior Indebtedness (including interest after
the  commencement of any such proceeding at the rate specified in the applicable
Senior Indebtedness) before the Holders of Notes will be entitled to receive any
payment with respect  to the Notes,  and until all  Obligations with respect  to
Senior  Indebtedness are  paid in  full in cash,  any distribution  to which the
Holders of  Notes would  be entitled  shall be  made to  the holders  of  Senior
Indebtedness  (except  that Holders  of Notes  may  receive securities  that are
subordinated at least to the same extent as the Notes are subordinated to Senior
Indebtedness and any securities issued  in exchange for Senior Indebtedness  and
Holders  of Notes may recover  payments made from the  trust described under the
caption "Legal Defeasance and Covenant Defeasance").
 
    The Company also may not  make any payment upon or  in respect of the  Notes
(except  in such subordinated  securities or from the  trust described under the
caption "Legal Defeasance  and Covenant  Defeasance") if  (i) a  default in  the
payment  of the principal of, premium, if  any, or interest on Designated Senior
Indebtedness occurs and is continuing beyond  any applicable period of grace  or
(ii)  any  other default  occurs and  is continuing  with respect  to Designated
Senior  Indebtedness  that  then  permits  holders  of  such  Designated  Senior
Indebtedness  to accelerate  its maturity and  the Trustee receives  a notice of
such  default  (a   "Payment  Blockage   Notice")  from  the   holders  or   the
representative of the holders of any Designated Senior Indebtedness. Payments on
the  Notes may and shall be  resumed (a) in the case  of a payment default, upon
the date on  which such default  is cured  or waived and  (b) in the  case of  a
nonpayment  default, the earlier of the date on which such nonpayment default is
cured or waived  or 179  days after  the date  on which  the applicable  Payment
Blockage  Notice  is  received, unless  the  maturity of  any  Designated Senior
Indebtedness has been  accelerated. No  new period  of payment  blockage may  be
commenced  by a Payment Blockage  Notice unless and until  360 days have elapsed
since the effectiveness  of the  immediately prior Payment  Blockage Notice.  No
nonpayment default that existed or was continuing on the date of delivery of any
Payment  Blockage Notice to  the Trustee shall be,  or be made,  the basis for a
subsequent Payment Blockage Notice.
 
    The Indenture  will further  require that  the Company  promptly notify  the
Representatives  of  holders of  Designated  Senior Indebtedness  and Designated
Guarantor Senior Indebtedness if payment of the Notes is accelerated because  of
any Event of Default.
 
   
    As a result of the subordination provisions described above, in the event of
an insolvency, bankruptcy, reorganization or liquidation of the Company, or upon
the  occurrence of a Change of Control  or an Asset Sale requiring repurchase by
the Company  of any  Notes, there  may  not be  sufficient assets  remaining  to
satisfy  the claims of the  Holders after satisfying the  claims of creditors of
the Company who are  holders of Senior Indebtedness  and claims of creditors  of
the  Company's Subsidiaries. See "Risk Factors -- Subordination of the Notes and
Subsidiary Guarantees."  On  a pro  forma  basis,  after giving  effect  to  the
Corporate   Reorganization,  the  Offerings  and  the  application  of  proceeds
therefrom, $0.4 million of  Senior Indebtedness of the  Company would have  been
outstanding at June 30, 1996. The Notes will also be effectively subordinated to
liabilities of the Company's Subsidiaries that are not Subsidiary Guarantors. On
a pro forma basis, the total liabilities of the Company's Subsidiaries were $6.5
million at June 30, 1996, all of which were operating liabilities. The Indenture
will  limit,  subject  to  certain financial  tests,  the  amount  of additional
Indebtedness, including Senior Indebtedness  and Guarantor Senior  Indebtedness,
that  the  Company and  its Subsidiaries  can incur.  See "Certain  Covenants --
Incurrence of Indebtedness and Issuance of Preferred Stock."
    
 
   
SUBSIDIARY GUARANTEES
    
 
   
    The Indenture does not  require any Subsidiary to  guarantee the payment  of
the   Notes  unless  such   Subsidiary  incurs  Indebtedness   (other  than  its
Indebtedness existing  on the  date of  the Indenture  and certain  intercompany
Indebtedness).    The   Indenture   requires   the   Company   to   cause   such
    
 
                                       56
<PAGE>
   
Subsidiary to fully  and unconditionally, jointly  and severally guarantee  (the
"Subsidiary Guarantees") the Company's payment obligations under the Notes prior
to  the incurrence of such Indebtedness. See "Certain Covenants -- Incurrence of
Indebtedness and Issuance  of Preferred Stock."  On the date  of the  Indenture,
there  will be no Subsidiary Guarantors. So  long as a Person is an Unrestricted
Subsidiary, such Person will not be required to become a Subsidiary Guarantor or
execute  a  Subsidiary  Guarantee.   See  "Certain  Covenants  --   Unrestricted
Subsidiaries." As a result, claims of creditors against the Subsidiaries and the
Unrestricted  Subsidiaries, including their trade  creditors and tort claimants,
will effectively have priority to the property and earnings of such subsidiaries
over claims of creditors of the Company, including the Holders. The  obligations
of each Subsidiary Guarantor under its Subsidiary Guarantee will be limited in a
manner  intended  to  result in  such  Subsidiary Guarantee  not  constituting a
fraudulent conveyance under applicable law.
    
 
   
    The Indenture will provide that no Subsidiary Guarantor may consolidate with
or merge with or into (whether or not such Subsidiary Guarantor is the surviving
Person) another Person whether or not affiliated with such Subsidiary  Guarantor
(other  than the  consolidation or  merger of a  Wholly Owned  Subsidiary of the
Company with another Wholly Owned Subsidiary of the Company or into the Company)
unless (i) subject  to the  provisions of  the following  paragraph, the  Person
formed  by or  surviving any  such consolidation or  merger (if  other than such
Subsidiary Guarantor) becomes a Subsidiary Guarantor pursuant to a  supplemental
indenture  or other agreement  in form and  substance reasonably satisfactory to
the Trustee, and (ii) immediately after  giving effect to such transaction,  (A)
no  Default or Event of Default would exist  or be continuing and (B) other than
in the case of the consolidation or merger of two or more Subsidiary  Guarantors
or  of one or more Subsidiary Guarantors with the Company, the Company would (A)
have Consolidated  Net  Worth immediately  after  the transaction  equal  to  or
greater than the Consolidated Net Worth of the Company immediately preceding the
transactions;  and (B) at the  time of such transaction  and after giving effect
thereto, be  permitted  to  incur  at least  $1.00  of  additional  Indebtedness
pursuant   to  the  Consolidated  Interest   Coverage  Ratio  and  the  Adjusted
Consolidated Net Tangible  Assets to Consolidated  Indebtedness Ratio tests  set
forth  in the first paragraph of the  covenant described below under the caption
"Certain Covenants  --  Incurrence of  Indebtedness  and Issuance  of  Preferred
Stock."
    
 
    The  Indenture  will  provide that  (i)  in the  event  of a  sale  or other
disposition of all of the assets of any Subsidiary Guarantor, by way of  merger,
consolidation or otherwise, or a sale or other disposition of all of the capital
stock  of  any Subsidiary  Guarantor  or (ii)  in  the event  that  a Subsidiary
Guarantor is properly designated as an Unrestricted Subsidiary, in each case, in
accordance with the provisions of the Indenture, then such Subsidiary  Guarantor
(in  the  event  of a  sale  or other  disposition,  by  way of  such  a merger,
consolidation or  otherwise, of  all of  the capital  stock of  such  Subsidiary
Guarantor  or  the  proper  designation  of  such  Subsidiary  Guarantor  as  an
Unrestricted Subsidiary in accordance with  the provisions of the Indenture)  or
the  corporation  acquiring  the property  (in  the  event of  a  sale  or other
disposition of  all  or substantially  all  of  the assets  of  such  Subsidiary
Guarantor),  will  be  released  and  relieved  of  any  obligations  under  its
Subsidiary Guarantee;  provided that  the Net  Proceeds of  such sale  or  other
disposition  are applied  in accordance  with the  applicable provisions  of the
Indenture. See "Certain Covenants -- Merger, Consolidation or Sale of Assets."
 
   
    The obligations of each Subsidiary Guarantor under its Subsidiary  Guarantee
are  subordinated  to  the  prior  payment  in  full  of  all  Guarantor  Senior
Indebtedness  of  such   Subsidiary  Guarantor  (including   any  guarantee   of
Indebtedness of the Company under the Credit Facility) to substantially the same
extent  as the  Notes are  subordinated to Senior  Indebtedness. On  a pro forma
basis, after giving effect  to the Corporate  Reorganization, the Offerings  and
the  application of proceeds  therefrom, no Guarantor  Senior Indebtedness would
have been outstanding as of June 30, 1996.
    
 
OPTIONAL REDEMPTION
 
    The  Notes  will  not  be  redeemable  at  the  Company's  option  prior  to
          ,  2001. Thereafter,  the Notes will  be subject to  redemption at the
option   of   the   Company,   in   whole   or   in   part,   upon   not    less
 
                                       57
<PAGE>
than  30 nor more than  60 days' notice, at  the redemption prices (expressed as
percentages of  principal  amount)  set  forth below  plus  accrued  and  unpaid
interest  to the applicable redemption date, if redeemed during the twelve-month
period beginning on           of the years indicated below:
 
<TABLE>
<CAPTION>
YEAR                                                                               PERCENTAGE
- ---------------------------------------------------------------------------------  -----------
<S>                                                                                <C>
2001.............................................................................            %
2002.............................................................................            %
2003.............................................................................            %
2004 and thereafter..............................................................     100.000%
</TABLE>
 
    Notwithstanding the foregoing, at any time on  or before            ,  1999,
the  Company may (but shall not have the  obligation to) redeem up to 30% of the
original aggregate principal amount of the Notes at a redemption price of      %
of the principal amount thereof, plus accrued and unpaid interest thereon to the
redemption date,  with  the net  proceeds  of an  Equity  Offering made  by  the
Company;  PROVIDED that at least 70% of  the aggregate principal amount of Notes
originally issued remain  outstanding immediately after  the occurrence of  such
redemption;  and PROVIDED, FURTHER,  that such redemption  shall occur within 75
days of the date of the closing of such Equity Offering.
 
    If less than all of the Notes are  to be redeemed at any time, selection  of
Notes  for redemption will be made by the  Trustee on a pro rata basis; PROVIDED
that no Notes of $1,000 or less shall be redeemed in part. Notices of redemption
shall be mailed by first class mail at least 30 but not more than 60 days before
the redemption date to  each Holder of  Notes to be  redeemed at its  registered
address.  If any Note is  to be redeemed in part  only, the notice of redemption
that relates  to such  Note shall  state  the portion  of the  principal  amount
thereof  to be redeemed. A new Note  in principal amount equal to the unredeemed
portion thereof  will  be  issued  in  the  name  of  the  Holder  thereof  upon
cancellation  of the original  Note. On and after  the redemption date, interest
ceases to accrue on Notes or portions thereof called for redemption.
 
MANDATORY REDEMPTION
 
    The Company is  not required to  make mandatory redemption  or sinking  fund
payments with respect to the Notes.
 
REPURCHASE AT THE OPTION OF HOLDERS
 
  CHANGE OF CONTROL
 
    Upon  the occurrence of a Change of  Control, each Holder of Notes will have
the right to require the Company to repurchase all or any part (equal to  $1,000
or  an integral multiple thereof)  of such Holder's Notes  pursuant to the offer
described below (the "Change of Control Offer") at an offer price in cash  equal
to  101%  of the  aggregate  principal amount  thereof  plus accrued  and unpaid
interest thereon  (the  "Change of  Control  Purchase  Price") to  the  date  of
purchase  (the "Change of  Control Payment Date"). Within  30 days following any
Change of Control, the Company will mail a notice to each Holder describing  the
transaction  or transactions that constitute the  Change of Control and offering
to repurchase Notes  pursuant to the  procedures required by  the Indenture  and
described in such notice. The Change of Control Payment Date shall be a business
day not less than 30 days nor more than 60 days after such notice is mailed. The
Company  will comply with the requirements of  Rule 14e-1 under the Exchange Act
and any other securities laws and regulations thereunder to the extent such laws
and regulations are applicable in connection with the repurchase of the Notes as
a result of a Change of Control.
 
    On the  Change of  Control Payment  Date, the  Company will,  to the  extent
lawful,  (1) accept for payment all  Notes or portions thereof properly tendered
pursuant to the Change of  Control Offer, (2) deposit  with the Paying Agent  an
amount  equal to the Change of Control Purchase Price in respect of all Notes or
portions thereof so tendered  and (3) deliver  or cause to  be delivered to  the
Trustee the Notes so accepted together with an Officers' Certificate stating the
aggregate  principal amount of Notes or  portions thereof being purchased by the
Company. The Paying Agent will promptly mail to each Holder of Notes so tendered
the  Change  of  Control   Payment  for  such  Notes,   and  the  Trustee   will
 
                                       58
<PAGE>
promptly  authenticate and mail  (or cause to  be transferred by  book entry) to
each Holder a new Note equal in  principal amount to any unpurchased portion  of
the  Notes surrendered, if  any; PROVIDED that each  such new Note  will be in a
principal amount of $1,000 or an  integral multiple thereof. The Indenture  will
provide  that, prior to complying  with the provisions of  this covenant, but in
any event within 30 days following a Change of Control, the Company will  either
repay  all outstanding Senior Indebtedness or  obtain the requisite consents, if
any, under all  agreements governing outstanding  Senior Indebtedness to  permit
the  repurchase of  Notes required by  this covenant. The  Company will publicly
announce the results of the Change of Control Offer on or as soon as practicable
after the Change of Control Payment Date.
 
    Except as described above with respect to a Change of Control, the Indenture
does not contain provisions that permit the Holders of the Notes to require that
the Company repurchase or  redeem the Notes  in the event of  a takeover by  any
persons  other than the Approved Shareholders,  or a recapitalization or similar
restructuring.
 
    The Credit Facility may provide that  certain change of control events  with
respect  to the Company would constitute a default thereunder. Any future credit
agreements or  other agreements  relating to  Senior Indebtedness  to which  the
Company  becomes a party may contain similar restrictions and provisions. In the
event a Change of Control occurs at  a time when the Company is prohibited  from
purchasing  Notes, the  Company could  seek the  consent of  its lenders  to the
purchase of Notes  or could attempt  to repay or  refinance the borrowings  that
contain such prohibition. If the Company does not obtain such a consent or repay
such  borrowings, the Company  will remain prohibited  from purchasing Notes. In
such case, the Company's failure to purchase tendered Notes would constitute  an
Event  of Default under the Indenture which would, in turn, constitute a default
under the Credit Facility. In  such circumstances, the subordination  provisions
in the Indenture would likely restrict payments to the Holders of Notes.
 
  ASSET SALES
 
    The  Indenture will provide that  the Company will not,  and will not permit
any of its Subsidiaries to, engage in  an Asset Sale unless (i) the Company  (or
such  Subsidiary) receives consideration at the time of such Asset Sale at least
equal to the fair market value, and in the case of a lease of assets under which
the Company or any of its Subsidiaries is the lessor, a lease providing for rent
and other  conditions  which are  no  less favorable  to  the Company  (or  such
Subsidiary)  in any material respect than  the then prevailing market conditions
(evidenced in each case by a resolution of the Board of Directors of such entity
set forth in an  Officers' Certificate delivered to  the Trustee) of the  assets
sold  or otherwise disposed of, and (ii) at  least 85% (100% in the case of such
lease payments) of the  consideration therefor received by  the Company or  such
Subsidiary  is in the form of cash or Cash Equivalents or properties used in the
Oil and Gas Business of the Company and its Subsidiaries.
 
    The Company may apply Net Proceeds of  an Asset Sale, at its option, (a)  to
permanently reduce Senior Indebtedness other than Senior Revolving Indebtedness,
(b)  to permanently reduce Senior Revolving Indebtedness (and to correspondingly
reduce commitments with  respect thereto), or  (c) to invest  in properties  and
assets  that will be  used in the  Oil and Gas  Business of the  Company and its
Subsidiaries. Pending  the  final application  of  any such  Net  Proceeds,  the
Company may temporarily reduce Senior Revolving Indebtedness or otherwise invest
such Net Proceeds in any manner that is not prohibited by the Indenture. Any Net
Proceeds  from  Asset Sales  that  are not  applied  within 270  days  after the
consummation of  an  Asset  Sale as  provided  in  the first  sentence  of  this
paragraph  will be  deemed to constitute  "Excess Proceeds."  When the aggregate
amount of Excess Proceeds exceeds $5.0 million, the Company will be required  to
make  an offer to all  Holders of Notes (an "Asset  Sale Offer") to purchase the
maximum principal  amount of  Notes that  may  be purchased  out of  the  Excess
Proceeds,  at  a purchase  price  in cash  in  an amount  equal  to 100%  of the
principal amount thereof plus accrued and unpaid interest thereon to the date of
purchase, in accordance with the procedures  set forth in the Indenture. To  the
extent  that the aggregate unpaid amount of  Notes tendered pursuant to an Asset
Sale Offer  is  less  than  the  Excess  Proceeds,  the  Company  may  use  such
 
                                       59
<PAGE>
surplus  Excess Proceeds for general corporate purposes. If the aggregate unpaid
amount of Notes  surrendered by  Holders thereof  exceeds the  amount of  Excess
Proceeds,  the Trustee  shall select  the Notes  to be  purchased on  a pro rata
basis. Upon completion of such offer to purchase, the amount of Excess  Proceeds
shall be reset at zero.
 
   
    The  Indenture prohibits the Company from directly or indirectly engaging in
an Asset  Sale  of any  Principal  Properties to  any  Subsidiary other  than  a
Subsidiary Guarantor.
    
 
CERTAIN COVENANTS
 
  OWNERSHIP OF CAPITAL STOCK
 
   
    The  Indenture  will provide  that the  Company will  not permit  any Person
(other than the Company or  any Wholly Owned Subsidiary  of the Company) to  own
any  Capital Stock  of any Subsidiary  of the  Company, and will  not permit any
Subsidiary of the Company to issue Capital Stock (except to the Company or to  a
Wholly  Owned Subsidiary) in each case  except (a) directors' qualifying shares,
(b) Capital Stock issued prior to the  time such Person becomes a Subsidiary  of
the Company, (c) if such Subsidiary merges with and into another Subsidiary, (d)
if  another  Subsidiary  merges  with  and into  such  Subsidiary,  (e)  if such
Subsidiary ceases to be  a Subsidiary (as a  result of the sale  of 100% of  the
shares of such Subsidiary, the Net Proceeds from which are applied in accordance
with  "Repurchase at the Option of Holders -- Asset Sales") or (f) Capital Stock
of a Subsidiary organized in a foreign jurisdiction required to be issued to, or
owned by, the government of such foreign jurisdiction or individual or corporate
citizens of such foreign jurisdiction in  order for such Subsidiary to  transact
business in such foreign jurisdiction.
    
 
  UNRESTRICTED SUBSIDIARIES
 
    The  Board of Directors of the Company may designate any of its Subsidiaries
as an Unrestricted  Subsidiary. A Subsidiary  may only be  so designated if  (i)
immediately  after  giving effect  to such  designation no  Default or  Event of
Default exists, (ii)  the Company  would, at the  time of  such designation  and
after giving pro forma effect thereto as if such designation had occurred at the
beginning of the applicable four-quarter period, have been permitted to incur at
least  $1.00 of  additional Indebtedness  pursuant to  the Consolidated Interest
Coverage Ratio and the Adjusted Consolidated Tangible Net Assets to Consolidated
Indebtedness Ratio  tests set  forth  in the  first  paragraph of  the  covenant
described  under  the caption  "-- Incurrence  of  Indebtedness and  Issuance of
Preferred Stock," and (iii) after  the date of the  Indenture and prior to  such
designation,  no  assets of  the Company  or  of any  Subsidiary of  the Company
(including, without limitation, Capital Stock of any such Subsidiary) shall have
been transferred, directly or indirectly, to any Unrestricted Subsidiary or  any
of  its Subsidiaries,  other than assets  transferred in the  ordinary course of
business and on terms that are no less favorable to the Company or the  relevant
Subsidiary  than those that would have been obtained in a comparable transaction
by the Company or  such Subsidiary with  an unrelated Person  and except to  the
extent   permitted  under  the  caption   "--  Restricted  Payments."  Any  such
designation by the Board of Directors of  the Company shall be evidenced to  the
Trustee  by filing with the Trustee a  certified copy of the Board Resolution of
the Company giving effect  to such designation and  an Officers' Certificate  of
the  Company  certifying  that  such  designation  complied  with  the foregoing
conditions.
 
    Any  Subsidiary  of  the  Company  shall  continue  to  be  an  Unrestricted
Subsidiary   only  if  it  (a)  has  no  Indebtedness  other  than  Non-Recourse
Indebtedness; (b) is a Person with respect to which neither the Company nor  any
of  its Subsidiaries has any direct or  indirect obligation (x) to subscribe for
additional Equity  Interests  or  (y)  to maintain  or  preserve  such  Person's
financial  condition or to cause such Person  to achieve any specified levels of
operating  results;  and  (c)  has  not  guaranteed  or  otherwise  directly  or
indirectly provided credit support for any Indebtedness of the Company or any of
its Subsidiaries. If, at any time, any Unrestricted Subsidiary fails to meet the
foregoing  requirements, such Unrestricted Subsidiary  shall thereafter cease to
be an Unrestricted Subsidiary for  purposes of the Indenture, such  Unrestricted
Subsidiary    shall    execute    and   deliver    a    supplemental   indenture
 
                                       60
<PAGE>
pursuant to which such Person  guarantees the payment of  the Notes on the  same
terms  and conditions as the Subsidiary  Guarantees and any Indebtedness of such
Unrestricted Subsidiary shall be  deemed to be incurred  by a Subsidiary of  the
Company  as  of such  date (and,  if such  Indebtedness is  not permitted  to be
incurred as of  such date  under the covenant  described under  the caption  "--
Incurrence  of Indebtedness and Issuance of  Preferred Stock," the Company shall
be in default of such covenant).
 
    The Board  of  Directors  of the  Company  may  at any  time  designate  any
Subsidiary,  if previously  designated as  an Unrestricted  Subsidiary, to  be a
Subsidiary; PROVIDED that such designation shall  be deemed to be an  incurrence
of  Indebtedness by a Subsidiary of  the Company of any outstanding Indebtedness
of such Subsidiary  and such  designation shall only  be permitted  if (i)  such
Indebtedness  is permitted  under the covenant  described under  the caption "--
Incurrence of Indebtedness and Issuance of Preferred Stock," (ii) no Default  or
Event of Default would be in existence following such designation and (iii) such
Subsidiary  shall execute and deliver a supplemental indenture pursuant to which
such Person guarantees the payment of the Notes on the same terms and conditions
as the Subsidiary Guarantees.
 
    As of the  date of the  Indenture, Costilla Redeco  Exploration, L.L.C.  and
Costilla  Redeco  Operating,  L.L.C.,  through which  the  Company  conducts its
Moldovan operations will be Unrestricted Subsidiaries.
 
  RESTRICTED PAYMENTS
 
    The Indenture will provide  that the Company will  not, and will not  permit
any  of its  Subsidiaries to,  directly or  indirectly: (i)  declare or  pay any
dividend or make  any distribution on  account of  the Company's or  any of  its
Subsidiaries' Equity Interests, other than dividends or distributions payable in
Equity  Interests (other than Disqualified Stock) of the Company or dividends or
distributions payable  to the  Company or  any Wholly  Owned Subsidiary  of  the
Company;  (ii) purchase,  redeem or  otherwise acquire  or retire  for value any
Equity Interests of the Company or any Subsidiary or Unrestricted Subsidiary  or
other  Affiliate of the Company (other than Equity Interests of the Company, any
Subsidiary or Unrestricted Subsidiary  owned by any  Wholly Owned Subsidiary  of
the  Company); (iii) make any principal payment on, or purchase, redeem, defease
or otherwise acquire  or retire for  value any Indebtedness  of (x) the  Company
that  is PARI PASSU with or subordinated to  the Notes (other than the Notes) or
(y) any Subsidiary of  the Company that  is PARI PASSU  with or subordinated  to
such  Subsidiary's Subsidiary Guarantee (other than Indebtedness secured by such
Subsidiary Guarantee)  ("PARI PASSU  Indebtedness"), in  each case,  prior to  a
scheduled  mandatory sinking fund payment date or maturity date or (iv) make any
Restricted Investment (all such payments and other actions set forth in  clauses
(i) through (iv) above being collectively referred to as "Restricted Payments"),
unless, at the time of and after giving effect to such Restricted Payment:
 
        (a) no Default or Event of Default shall have occurred and be continuing
    or would occur as a consequence thereof;
 
        (b)  the Company would, at the time of such Restricted Payment and after
    giving pro forma effect thereto as if such Restricted Payment had been  made
    at  the beginning of the applicable four-quarter period, have been permitted
    to  incur  at  least  $1.00  of  additional  Indebtedness  pursuant  to  the
    Consolidated  Interest  Coverage  Ratio and  the  Adjusted  Consolidated Net
    Tangible Assets to Consolidated  Indebtedness Ratio tests  set forth in  the
    first  paragraph  of  the covenant  described  below under  the  caption "--
    Incurrence of Indebtedness and Issuance of Preferred Stock"; and
 
   
        (c) such Restricted Payment,  together with the  aggregate of all  other
    Restricted Payments made by the Company and its Subsidiaries on or after the
    date  of the Indenture  (excluding Restricted Payments  permitted by clauses
    (ii), (iii), (iv) and  (v) of the next  succeeding paragraph), is less  than
    the  sum of (i)  50% of the Consolidated  Net Income of  the Company and its
    Subsidiaries for  the  period (taken  as  one accounting  period)  from  the
    beginning of the first day of the fiscal
    
 
                                       61
<PAGE>
   
    month  during which the Indenture  was executed and delivered  to the end of
    the  Company's  most  recently  ended  fiscal  quarter  for  which  internal
    financial  statements are available  at the time  of such Restricted Payment
    (or, if such Consolidated Net Income for such period is a deficit, less 100%
    of such deficit), plus (ii) 100% of the aggregate net cash proceeds received
    by the Company as capital contributions to the Company or from the issue  or
    sale  after the date of the Indenture  of Equity Interests of the Company or
    of debt securities of the Company that have been converted into such  Equity
    Interests (other than Equity Interests (or convertible debt securities) sold
    to  a Subsidiary or an Unrestricted Subsidiary of the Company and other than
    Disqualified  Stock  or  debt  securities  that  have  been  converted  into
    Disqualified  Stock) other  than the Common  Stock sold in  the Common Stock
    Offering.
    
 
    The foregoing  clauses (b)  and  (c), however,  will  not prohibit  (i)  the
payment of any dividend within 60 days after the date of declaration thereof, if
at said date of declaration such payment would have complied with the provisions
of  the Indenture; (ii) the  payment of any dividend  on Equity Interests of the
Company (other  than Disqualified  Stock)  payable solely  in shares  of  Equity
Interests  of the Company (other than Disqualified Stock); (iii) any dividend or
other distribution payable from  a Subsidiary of the  Company to the Company  or
any  Wholly Owned  Subsidiary; (iv) the  making of any  Restricted Investment in
exchange for, or  out of  the proceeds  of, the  substantially concurrent  sale,
issuance  or exchange (other than to a Subsidiary or any Unrestricted Subsidiary
of the Company)  of Equity  Interests of  the Company  (other than  Disqualified
Stock);  PROVIDED, that  any net  cash proceeds that  are utilized  for any such
Restricted Investment  shall  be  excluded  from clause  (c)  of  the  preceding
paragraph;  (v) the redemption,  repurchase, retirement or  other acquisition of
any Equity Interests of the Company in exchange for, or out of the proceeds  of,
the  substantially  concurrent  sale,  issuance or  exchange  (other  than  to a
Subsidiary or  any  Unrestricted Subsidiary  of  the Company)  of  other  Equity
Interests  of the Company (other than any Disqualified Stock); PROVIDED that any
net cash  proceeds  that  are  utilized for  any  such  redemption,  repurchase,
retirement  or  other  acquisition shall  be  excluded  from clause  (c)  of the
preceding paragraph; and (vi) the  defeasance, redemption or repurchase of  PARI
PASSU  Indebtedness prior to a scheduled  mandatory sinking fund payment date or
maturity date thereof with the net cash proceeds from an incurrence of Permitted
Refinancing Indebtedness  or  the  substantially concurrent  sale,  issuance  or
exchange  (other  than to  a Subsidiary  or any  Unrestricted Subsidiary  of the
Company) of Equity Interests of the  Company (other than Disqualified Stock)  or
the  purchase, redemption or  acquisition of PARI PASSU  Indebtedness prior to a
scheduled mandatory sinking fund payment  date or maturity date thereof  through
the  issuance in exchange thereof of Equity Interests of the Company (other than
Disqualified Stock); PROVIDED, that any net cash proceeds that are utilized  for
any  such defeasance, redemption,  repurchase, purchase or  acquisition shall be
excluded from clause (c) of the preceding paragraph.
 
    The amount of all  Restricted Payments (other than  cash) shall be the  fair
market  value (evidenced by a resolution of  the Board of Directors set forth in
an Officers' Certificate delivered to the Trustee) on the date of the Restricted
Payment of  the asset(s)  proposed to  be  transferred by  the Company  or  such
Subsidiary,  as the case may  be, pursuant to the  Restricted Payment. Not later
than the date of making any Restricted Payment, the Company shall deliver to the
Trustee an Officers'  Certificate of  the Company stating  that such  Restricted
Payment  is permitted  and setting forth  the basis upon  which the calculations
required by the covenant  described under the  caption "-- Restricted  Payments"
were  computed,  which  calculations  may be  based  upon  the  Company's latest
available financial statements.
 
  INCURRENCE OF INDEBTEDNESS AND ISSUANCE OF PREFERRED STOCK
 
    The Indenture will provide  that the Company will  not, and will not  permit
any  of  its  Subsidiaries to,  directly  or indirectly,  create,  incur, issue,
assume,  guarantee   or  otherwise   become  directly   or  indirectly   liable,
contingently   or  otherwise,  with  respect   to  (collectively,  "incur")  any
Indebtedness (including Acquired  Indebtedness) and  that the  Company will  not
issue  any Disqualified  Stock and  will not permit  any of  its Subsidiaries to
issue   any    shares   of    preferred   stock;    PROVIDED,   HOWEVER,    that
 
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the  Company may  incur Indebtedness  (including Acquired  Indebtedness) and the
Company may issue shares of Disqualified Stock if: (i) the Consolidated Interest
Coverage Ratio for the Company's most  recently ended four full fiscal  quarters
for  which internal financial statements are available immediately preceding the
date on  which such  additional Indebtedness  is incurred  or such  Disqualified
Stock  is issued  would have been  at least,  during the period  until the first
anniversary of the date of the Indenture, 2.25 to 1, and, thereafter, 2.5 to  1,
in each case, determined on a pro forma basis (including a pro forma application
of  the  net proceeds  therefrom), as  if the  additional Indebtedness  had been
incurred, or the Disqualified Stock had been issued, as the case may be, at  the
beginning  of  such  four-quarter  period; (ii)  the  Adjusted  Consolidated Net
Tangible Assets  would have  been at  least 150%  of Consolidated  Indebtedness,
determined  on a pro forma  basis (including a pro  forma application of the net
proceeds therefrom) and (iii) no Default or Event of Default shall have occurred
and be continuing  or would occur  as a consequence  thereof; PROVIDED, that  no
Guarantee  may be  incurred pursuant  to this  paragraph, unless  the guaranteed
Indebtedness is incurred by the Company pursuant to this paragraph.
    
 
    The foregoing provisions will not apply to:
 
        (i) the  incurrence by  the  Company of  Indebtedness under  the  Credit
    Facility  (and the incurrence  by Subsidiaries of  Guarantees thereof) in an
    aggregate principal amount at any  time outstanding (with letters of  credit
    being  deemed  to have  a principal  amount equal  to the  maximum potential
    liability of the Company and its Subsidiaries thereunder) not to exceed  $50
    million,  less  the aggregate  amount  of all  Net  Proceeds of  Asset Sales
    applied to permanently reduce the outstanding amount or the commitments with
    respect to such Indebtedness pursuant to the covenant described above  under
    the caption "-- Asset Sales";
 
        (ii)  the incurrence by  the Company of  Indebtedness represented by the
    Notes and of its Subsidiaries of Indebtedness represented by the  Subsidiary
    Guarantees;
 
       (iii)  the  incurrence  by the  Company  or  any of  its  Subsidiaries of
    Permitted Refinancing Indebtedness in exchange  for, or the net proceeds  of
    which  are used to extend, refinance, renew, replace, defease or refund, any
    Indebtedness described in the foregoing clause (ii);
 
       (iv) the  incurrence  by  the  Company or  any  of  its  Subsidiaries  of
    intercompany Indebtedness between or among the Company and any of its Wholly
    Owned  Subsidiaries  or  between  or among  any  Wholly  Owned Subsidiaries;
    PROVIDED that, in the case of Indebtedness of the Company, such  obligations
    shall  be unsecured and subordinated  in case of an  event of default in all
    respects to the Company's obligations  pursuant to the Notes; and  PROVIDED,
    however,  that (i) any  subsequent issuance or  transfer of Equity Interests
    that results in any such  Indebtedness being held by  a Person other than  a
    Wholly  Owned Subsidiary  and (ii)  any sale or  other transfer  of any such
    Indebtedness to a Person that  is not either the  Company or a Wholly  Owned
    Subsidiary  shall be  deemed, in each  case, to constitute  an incurrence of
    such Indebtedness by the Company or such Subsidiary, as the case may be;
 
        (v) the  incurrence  by the  Company  of Hedging  Obligations  that  are
    incurred  for  the purpose  of  fixing or  hedging  interest rate  risk with
    respect to any floating rate Indebtedness that is permitted by the Indenture
    to  be  incurred;  PROVIDED  that,  the  notional  amount  of  such  Hedging
    Obligations  does not  exceed the  principal amount  of the  Indebtedness to
    which such Hedging Obligations relate;
 
       (vi) the incurrence by the Company of Hedging Obligations under commodity
    hedging and  currency exchange  agreements; PROVIDED  that, such  agreements
    were  entered into  in the  ordinary course of  business for  the purpose of
    limiting risks that arise in the ordinary course of business;
 
   
       (vii) The incurrence by the Subsidiaries of Indebtedness in existence  on
    the date of the Indenture; and
    
 
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<PAGE>
   
      (viii)  the incurrence by the Company and its Subsidiaries of Indebtedness
    (in  addition  to  Indebtedness  permitted  by  any  other  clause  of  this
    paragraph)  in an aggregate principal amount  at any time outstanding not to
    exceed $10.0 million:
    
 
   
provided that no Subsidiary may  incur any Indebtedness other than  Indebtedness
described  in the foregoing  clauses (iv) or (vii)  unless such Subsidiary shall
have executed and delivered a Subsidiary Guarantee and such Subsidiary Guarantee
remains in  full force  and effect  (unless terminated  in accordance  with  the
provisions of the Indenture).
    
 
  LIENS
 
    The  Indenture will provide that  the Company will not,  and will not permit
any of its  Subsidiaries to, directly  or indirectly, create,  incur, assume  or
suffer  to exist  any Lien (other  than Permitted  Liens but only  to the extent
securing obligations not constituting  Indebtedness) on any  of its assets,  now
owned  or  hereafter  acquired,  securing  any  Indebtedness  other  than Senior
Indebtedness unless the Notes  are secured equally and  ratably with such  other
Indebtedness;  PROVIDED that,  if such  Indebtedness is  by its  terms expressly
subordinate  to  the  Notes,  the  Lien  securing  such  subordinate  or  junior
Indebtedness shall be subordinate and junior to the Lien securing the Notes with
the  same relative  priority as such  subordinated or  junior Indebtedness shall
have with respect to the Notes.
 
  DIVIDEND AND OTHER PAYMENT RESTRICTIONS AFFECTING SUBSIDIARIES
 
    The Indenture will provide  that the Company will  not, and will not  permit
any of its Subsidiaries to, directly or indirectly, create or otherwise cause or
suffer  to  exist or  become  effective any  encumbrance  or restriction  on the
ability  of  any  Subsidiary  to  (i)(a)   pay  dividends  or  make  any   other
distributions  to the Company or any of its Subsidiaries on its Capital Stock or
with respect to  any other  interest or participation  in, or  measured by,  its
profits,  or  (b)  pay  any indebtedness  owed  to  the Company  or  any  of its
Subsidiaries, (ii)  make  loans  or  advances  to the  Company  or  any  of  its
Subsidiaries or (iii) transfer any of its properties or assets to the Company or
any  of its  Subsidiaries, (iv) transfer  any of  its property or  assets to the
Company or any of its Subsidiaries, (v) grant liens or security interests on the
assets in favor  of the Holders  of Notes, or  (vi) guarantee the  Notes or  any
renewals  or refinancings thereof, except  for such encumbrances or restrictions
existing under or by reason of (A) the Credit Facility, the Indenture, the Notes
or any other agreement in existence on the date of the Indenture, (B) applicable
law, (C) any instrument  governing Acquired Indebtedness of  Capital Stock of  a
Person  acquired by the Company  or any of its Subsidiaries  as in effect at the
time of such acquisition  (except to the extent  such Acquired Indebtedness  was
incurred  in connection  with or  in contemplation  of such  acquisition), which
encumbrance or restriction is not applicable to any Person, or the properties or
assets of any Person, other  than the Person, or the  property or assets of  the
Person, so acquired, PROVIDED that the Consolidated EBITDA of such Person is not
taken  into account in determining whether such acquisition was permitted by the
terms of the Indenture, or (D) Permitted Refinancing Indebtedness, PROVIDED that
the  restrictions  contained   in  the  agreements   governing  such   Permitted
Refinancing  Indebtedness are  no more restrictive  than those  contained in the
agreements governing the Indebtedness being refinanced.
 
  LIMITATION ON LAYERING INDEBTEDNESS
 
    The Indenture will provide that the  Company will not incur, create,  issue,
assume,  guarantee  or  otherwise become  liable  for any  Indebtedness  that is
subordinate or junior in right of payment to any Senior Indebtedness and  senior
in any respect in right of payment to the Notes.
 
  MERGER, CONSOLIDATION OR SALE OF ASSETS
 
    The  Indenture will provide that  the Company will not,  and will not permit
any Subsidiary to,  in a single  transaction or series  of related  transactions
consolidate  or merge with or into (other  than the consolidation or merger of a
Wholly Owned Subsidiary of the Company  with another Wholly Owned Subsidiary  of
the  Company or into the Company) (whether or not the Company or such Subsidiary
is the  surviving  corporation),  or  directly  and/or  indirectly  through  its
Subsidiaries  sell, assign, transfer, lease, convey  or otherwise dispose of all
or  substantially   all  of   its  properties   or  assets   (determined  on   a
 
                                       64
<PAGE>
consolidated basis for the Company and its Subsidiaries taken as a whole) in one
or  more related transactions  to, another corporation,  Person or entity unless
(i) either (a) the Company, in the case of a transaction involving the  Company,
or  such Subsidiary, in the case of a transaction involving a Subsidiary, is the
surviving corporation or (b) in the case of a transaction involving the Company,
the entity or the Person formed by or surviving any such consolidation or merger
(if other than the Company) or to which such sale, assignment, transfer,  lease,
conveyance  or other disposition shall have been made is a corporation organized
or existing  under the  laws of  the United  States, any  state thereof  or  the
District  of Columbia and assumes  all the obligations of  the Company under the
Notes and  the  Indenture  pursuant  to  a  supplemental  indenture  in  a  form
reasonably  satisfactory to the Trustee; (ii) immediately after such transaction
no Default or Event of Default exists;  and (iii) the Company or, if other  than
the  Company, the entity or Person formed by or surviving any such consolidation
or merger, or  to which such  sale, assignment, transfer,  lease, conveyance  or
other  disposition shall  have been  made (A)  will have  Consolidated Net Worth
immediately after the transaction equal to or greater than the Consolidated  Net
Worth  of the Company immediately preceding the transaction and (B) will, at the
time of such transaction and  after giving pro forma  effect thereto as if  such
transaction had occurred at the beginning of the applicable four-quarter period,
be  permitted to incur at least $1.00 of additional Indebtedness pursuant to the
Consolidated Interest Coverage Ratio and the Adjusted Consolidated Net  Tangible
Assets to Consolidated Indebtedness Ratio tests set forth in the first paragraph
of the covenant described above under the caption "-- Incurrence of Indebtedness
and Issuance of Preferred Stock."
 
  TRANSACTIONS WITH AFFILIATES
 
    The  Indenture will provide that  the Company will not,  and will not permit
any of  its Subsidiaries  to, after  the  date of  the Indenture,  sell,  lease,
transfer or otherwise dispose of any of its properties or assets to, or make any
payment  to, or purchase any property or assets from, or enter into or suffer to
exist any transaction or  series of transactions, or  make any agreement,  loan,
advance  or guarantee with,  or for the  benefit of, any  Affiliate (each of the
foregoing,  an   "Affiliate   Transaction"),   other   than   Exempt   Affiliate
Transactions, unless (i) such Affiliate Transaction is on terms that are no less
favorable to the Company or the relevant Subsidiary (as reasonably determined by
the  Company)  than  those  that  would  have  been  obtained  in  a  comparable
transaction by the Company or such Subsidiary with an unrelated Person and  (ii)
the  Company  delivers  to  the  Trustee  (a)  with  respect  to  any  Affiliate
Transaction entered into  after the  date of the  Indenture involving  aggregate
consideration  in excess of $1.0 million, a resolution of the Board of Directors
set forth in an Officers' Certificate certifying that such Affiliate Transaction
complies with clause  (i) above  and that  such Affiliate  Transaction has  been
approved  by a majority of  the disinterested members of  the Board of Directors
and  (b)  with  respect  to   any  Affiliate  Transaction  involving   aggregate
consideration  in excess of $5.0  million, an opinion as  to the fairness to the
Company or such Subsidiary of such Affiliate Transaction from a financial  point
of view issued by an investment banking firm of national standing.
 
  SALE AND LEASEBACK
 
    The  Company will not, and will not permit any of its Subsidiaries to, enter
into  any  Sale  and  Leaseback  Transaction  unless  (a)  the  Company  or  its
Subsidiaries  entering  into  such  Sale and  Leaseback  Transaction  could have
incurred the  Indebtedness  relating  to such  Sale  and  Leaseback  Transaction
pursuant  to the "-- Incurrence of Indebtedness and Issuance of Preferred Stock"
and "-- Liens" covenants  and (b) the  Net Proceeds of  such Sale and  Leaseback
Transaction  are at  least equal to  the fair  market value of  such property as
determined by the Board of Directors of the Company.
 
  REPORTS
 
    The Indenture will provide  that, whether or not  required by the rules  and
regulations of the Commission, so long as any Notes are outstanding, the Company
will  furnish to the Holders of Notes, and file with the Trustee, within 15 days
after it is, or would have been,  required to file such with the Commission  (i)
all  quarterly and annual financial information that  is or would be required to
be contained in  a filing  with the  Commission on Forms  10-Q and  10-K if  the
Company is or were required
 
                                       65
<PAGE>
to  file  such  Forms,  including a  "Management's  Discussion  and  Analysis of
Financial Condition and Results of Operations"  and, with respect to the  annual
information  only,  a  report  thereon by  the  Company's  certified independent
accountants and (ii) all  current reports that  are or would  be required to  be
filed with the Commission on Form 8-K if the Company is or were required to file
such  reports. In addition, whether or not required by the rules and regulations
of the Commission,  the Company will  file a  copy of all  such information  and
reports  with the Commission for public availability (unless the Commission will
not accept such  a filing)  and make  such information  available to  securities
analysts and prospective investors upon written request.
 
  EVENTS OF DEFAULT AND REMEDIES
 
   
    The  Indenture will provide that each  of the following constitutes an Event
of Default: (i) default for 30 days in  the payment when due of interest on  the
Notes  (whether  or  not  prohibited  by  the  subordination  provisions  of the
Indenture); (ii) default in payment when  due (upon redemption or otherwise)  of
the  principal of or premium, if any, on the Notes (whether or not prohibited by
the subordination provisions of the Indenture); (iii) failure by the Company  to
comply with the provisions described under the captions "Repurchase at Option of
Holders -- Change of Control," "Repurchase at Option of Holders -- Asset Sales,"
"--  Ownership of  Capital Stock," "--  Restricted Payments,"  "-- Incurrence of
Indebtedness and Issuance of  Preferred Stock" or  "-- Merger, Consolidation  or
Sale  of Assets"; (iv)  failure by the Company  or any of  its Subsidiary for 60
days after notice by  the Trustee or  Holders of at least  25% of the  aggregate
principal  amount  of the  Notes outstanding  to  comply with  any of  its other
agreements in  the Indenture  or  the Notes;  (v)  default under  any  mortgage,
indenture or instrument under which there may be issued or by which there may be
secured  or evidenced any Indebtedness for money  borrowed by the Company or any
of its Subsidiaries (or the payment of which is guaranteed by the Company or any
of its Subsidiaries) whether  such Indebtedness or Guarantee  now exists, or  is
created  after  the date  of the  Indenture, which  default (a)  is caused  by a
failure to  pay principal  of such  Indebtedness at  final maturity  thereof  (a
"Payment Default") or (b) results in the acceleration of such Indebtedness prior
to  its express  maturity and, in  each case,  the principal amount  of any such
Indebtedness, together with the principal amount of any other such  Indebtedness
under  which there has been a Payment Default  or the maturity of which has been
so accelerated, aggregates $10 million or  more; (vi) failure by the Company  or
any  of its Subsidiaries to pay final judgments (not fully covered by insurance)
aggregating in excess of $1 million, which judgments are not paid, discharged or
stayed for a period of 60 days; (vii) certain events of bankruptcy or insolvency
with respect  to the  Company or  any of  its Subsidiaries  or any  Unrestricted
Subsidiary;   and  (viii)  any  Subsidiary  Guarantor  attempts  to  revoke  its
Subsidiary Guarantee or contest its  validity or any Subsidiary Guarantee  shall
not  be in full force and effect (other than in accordance with the terms of the
Indenture).
    
 
    If any Event of Default occurs and is continuing, the Trustee or the Holders
of at least 25% in  principal amount of the  then outstanding Notes may  declare
all  the Notes to be due and payable immediately. Notwithstanding the foregoing,
in the case of an Event of Default arising from certain events of bankruptcy  or
insolvency  with respect  to the Company  or any Subsidiary  or any Unrestricted
Subsidiary, all outstanding Notes  will become due  and payable without  further
action  or notice.  Holders of the  Notes may  not enforce the  Indenture or the
Notes except  as provided  in  the Indenture.  Subject to  certain  limitations,
Holders  of a  majority in  principal amount of  the then  outstanding Notes may
direct the Trustee in its exercise of any trust or power. The Indenture provides
that if a Default occurs and  is continuing, generally the Trustee must,  within
90 days after the occurrence of such default, give to the Holders notice of such
Default.  The  Trustee may  withhold from  Holders  of the  Notes notice  of any
continuing Default or  Event of Default  (except a Default  or Event of  Default
relating  to the  payment of principal  or premium,  if any, or  interest) if it
determines that withholding notice is in their interest.
 
    The Holders of a  majority in aggregate principal  amount of the Notes  then
outstanding  by notice to the Trustee may on behalf of the Holders of all of the
Notes waive any existing Default or Event of Default and its consequences  under
the   Indenture   except  a   continuing  Default   or   Event  of   Default  in
 
                                       66
<PAGE>
the payment of  interest or premium  on, or the  principal of, the  Notes or  in
respect  of a provision that cannot be  amended or waived without the consent of
the Holder affected. See "Amendment, Supplement and Waiver."
 
    The Company  is required  to deliver  to the  Trustee annually  a  statement
regarding  compliance  with  the Indenture,  and  the Company  is  required upon
becoming aware of any Default or Event  of Default, to deliver to the Trustee  a
statement specifying such Default or Event of Default.
 
NO PERSONAL LIABILITY OF DIRECTORS, OFFICERS, EMPLOYEES AND STOCKHOLDERS
 
    No  director, officer, employee, incorporator  or stockholder of the Company
or any Subsidiary, as such, shall have any liability for any obligations of  the
Company  under the  Notes or  the Indenture  or the  Subsidiary Guarantors under
their Subsidiary Guarantees  or for any  claim based  on, in respect  of, or  by
reason of, such obligations or their creation. Each Holder of Notes by accepting
a  Note waives and releases all such  liability. The waiver and release are part
of the consideration for issuance of the Notes. Such waiver may not be effective
to waive liabilities under the federal securities laws and it is the view of the
Commission that such waiver is against public policy.
 
LEGAL DEFEASANCE AND COVENANT DEFEASANCE
 
    The Company may, at  its option and at  any time, elect to  have all of  its
obligations   discharged  with   respect  to   the  outstanding   Notes  ("Legal
Defeasance") except  for (i)  the  rights of  Holders  of outstanding  Notes  to
receive  payments in respect of the principal  of, premium, if any, and interest
on such Notes when such payments are due from the trust referred to below,  (ii)
the Company's obligations with respect to the Notes concerning issuing temporary
Notes, registration of Notes, mutilated, destroyed, lost or stolen Notes and the
maintenance  of an office or agency for  payment and money for security payments
held in trust, (iii)  the rights, powers, trusts,  duties and immunities of  the
Trustee,  and the  Company's obligations  in connection  therewith and  (iv) the
Legal Defeasance provisions of the Indenture.  In addition, the Company may,  at
its  option  and at  any  time, elect  to have  the  obligations of  the Company
released with respect to certain covenants  that are described in the  Indenture
("Covenant  Defeasance")  and  thereafter  any  omission  to  comply  with  such
obligations shall not constitute a Default  or Event of Default with respect  to
the  Notes.  In  the  event  Covenant  Defeasance  occurs,  certain  events (not
including nonpayment,  bankruptcy, receivership,  rehabilitation and  insolvency
events)  described under "Events of Default"  will no longer constitute an Event
of Default with respect to the Notes.
 
    In order to exercise either Legal Defeasance or Covenant Defeasance, (i) the
Company must irrevocably deposit with the Trustee, in trust, for the benefit  of
the  Holders of Notes, cash in  U.S. dollars, noncallable Government Securities,
or a combination thereof, in such amounts as will be sufficient, in the  opinion
of  a nationally recognized  firm of independent public  accountants, to pay the
principal of, premium,  if any,  and interest on  the outstanding  Notes on  the
stated  maturity or on the  applicable redemption date, as  the case may be, and
the Company must specify whether the Notes are being defeased to maturity or  to
a  particular redemption date; (ii) in the case of Legal Defeasance, the Company
shall have delivered to the Trustee an  opinion of counsel in the United  States
reasonably  acceptable  to  the  Trustee confirming  that  (A)  the  Company has
received from, or there  has been published by,  the Internal Revenue Service  a
ruling  or (B) since the date  of the Indenture, there has  been a change in the
applicable federal income tax law, in either case to the effect that, and  based
thereon  such  opinion  of  counsel  shall  confirm  that,  the  Holders  of the
outstanding Notes will not recognize income, gain or loss for federal income tax
purposes as a result  of such Legal  Defeasance and will  be subject to  federal
income  tax on the  same amounts, in  the same manner  and at the  same times as
would have been the case if such Legal Defeasance had not occurred; (iii) in the
case of Covenant Defeasance, the Company shall have delivered to the Trustee  an
opinion  of counsel  in the United  States reasonably acceptable  to the Trustee
confirming that the Holders of the outstanding Notes will not recognize  income,
gain  or  loss for  federal income  tax purposes  as a  result of  such Covenant
Defeasance and will be subject to federal income tax on the same amounts, in the
same manner and at the same times as  would have been the case if such  Covenant
Defeasance had not occurred; (iv) no
 
                                       67
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Default or Event of Default shall have occurred and be continuing on the date of
such  deposit  (other than  a Default  or  Event of  Default resulting  from the
borrowing of  funds to  be applied  to such  deposit) or  insofar as  Events  of
Default  from bankruptcy or insolvency events are  concerned, at any time in the
period ending  on the  123rd  day after  the date  of  deposit; (v)  such  Legal
Defeasance  or Covenant Defeasance will not result  in a breach or violation of,
or constitute a default under any  material agreement or instrument (other  than
the  Indenture) to which the Company or any of its Subsidiaries is a party or by
which the Company or  any of its  Subsidiaries is bound;  (vi) the Company  must
deliver to the Trustee an Officers' Certificate stating that the deposit was not
made  by the  Company with the  intent of  preferring the Holders  of Notes over
other creditors of the Company with the intent of defeating, hindering, delaying
or defrauding creditors  of the Company  or others; and  (vii) the Company  must
deliver  to the Trustee an Officers' Certificate and an opinion of counsel, each
stating that all conditions  precedent relating to the  Legal Defeasance or  the
Covenant Defeasance have been complied with.
 
TRANSFER AND EXCHANGE
 
    A  Holder may transfer  or exchange Notes in  accordance with the Indenture.
The Company, the  Registrar and the  Trustee may require  a Holder, among  other
things,  to furnish appropriate  endorsements and transfer  documents as well as
certifications, legal opinions and other information and the Company may require
a Holder  to  pay any  taxes  and  fees required  by  law or  permitted  by  the
Indenture. The Company is not required to transfer or exchange any Note selected
for  redemption. Also, the Company  is not required to  transfer or exchange any
Note for a period of 15 days before a selection of Notes to be redeemed.
 
    The registered Holder of a Note will be  treated as the owner of it for  all
purposes.
 
AMENDMENT, SUPPLEMENT AND WAIVER
 
   
    Except as provided in the next two succeeding paragraphs, the Indenture, the
Subsidiary  Guarantees  or the  Notes may  be amended  or supplemented  with the
consent of the Holders of at least  a majority in principal amount of the  Notes
then  outstanding (including consents obtained in connection with a tender offer
or exchange offer for  Notes), and any existing  default or compliance with  any
provision of the Indenture, the Subsidiary Guarantees or the Notes may be waived
with  the consent of the  Holders of a majority in  principal amount of the then
outstanding Notes (including consents obtained in connection with a tender offer
or exchange offer for Notes).
    
 
   
    Without the consent of each Holder affected, an amendment or waiver may  not
(with  respect to  any Notes  held by  a nonconsenting  Holder): (i)  reduce the
principal amount of Notes whose Holders must consent to an amendment, supplement
or waiver, (ii) reduce the principal of or change the fixed maturity of any Note
or alter the provisions with respect to the redemption of the Notes (other  than
provisions   relating  to  the  covenants  described  above  under  the  caption
"Repurchase at the Option of Holders"), (iii)  reduce the rate of or change  the
time  for payment  of interest  on any Note,  (iv) waive  a Default  or Event of
Default in the payment of  principal of or premium, if  any, or interest on  the
Notes  (except a rescission  of acceleration of  the Notes by  the Holders of at
least a majority in aggregate principal amount of the Notes and a waiver of  the
payment default that resulted from such acceleration), (v) make any Note payable
in  money other  than that  stated in  the Notes,  (vi) make  any change  in the
provisions of the Indenture, or the Subsidiary Guarantees relating to waivers of
past Defaults or the rights of Holders of Notes to receive payments of principal
of or  premium, if  any, or  interest on  the Notes,  (vii) waive  a  redemption
payment  with respect to any  Note (other than a payment  required by one of the
covenants described  above  under  the  caption "Repurchase  at  the  Option  of
Holders")  or  (viii) make  any  change in  the  foregoing amendment  and waiver
provisions.
    
 
   
    Notwithstanding the foregoing, without the  consent of any Holder of  Notes,
the  Company  and  the  Trustee  may  amend  or  supplement  the  Indenture, the
Subsidiary  Guarantees  or  the   Notes  to  cure   any  ambiguity,  defect   or
inconsistency, to provide for uncertificated Notes in addition to or in place of
certificated  Notes, to provide for the  assumption of the Company's obligations
to Holders of Notes in the case of a merger or consolidation, to make any change
that would provide any additional rights or
    
 
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benefits to the Holders  of Notes or  that does not  adversely affect the  legal
rights under the Indenture of any such Holder, or to comply with requirements of
the Commission in order to effect or maintain the qualification of the Indenture
under the Trust Indenture Act.
 
CONCERNING THE TRUSTEE
 
    The  State  Street Bank  and Trust  Company  will be  the Trustee  under the
Indenture. The  Trustee's current  address is  Corporate Trust  Department,  Two
International Place, 4th Floor, Boston, Massachusetts 02110.
 
    The  Holders of a majority in principal amount of the then outstanding Notes
will have the  right to  direct the  time, method  and place  of conducting  any
proceeding  for  exercising  any remedy  available  to the  Trustee,  subject to
certain exceptions. The  Indenture provides  that in  case an  Event of  Default
shall  occur (which shall  not be cured),  the Trustee will  be required, in the
exercise of its power, to use the degree of care of a prudent man in the conduct
of his own affairs.  Subject to such  provisions, the Trustee  will be under  no
obligation  to exercise any of  its rights or powers  under the Indenture at the
request of any Holder  of Notes, unless  such Holder shall  have offered to  the
Trustee security and indemnity satisfactory to it against any loss, liability or
expense.
 
ADDITIONAL INFORMATION
 
    Anyone  who  receives this  Prospectus may  obtain a  copy of  the Indenture
without charge by  writing to  Costilla Energy,  Inc., 400  West Illinois,  10th
Floor, Midland, Texas 79701, Attention: Chief Financial Officer.
 
BOOK-ENTRY, DELIVERY AND FORM
 
    The  Notes to be  sold as set forth  herein will initially  be issued in the
form of one Global Note (the "Global  Note"). The Global Note will be  deposited
on the date of the closing of the sale of the Notes offered hereby (the "Closing
Date")  with  the Trustee  as custodian  for The  Depository Trust  Company (the
"Depositary") and  registered in  the name  of Cede  & Co.,  as nominee  of  the
Depositary (such nominee being referred to herein as the "Global Note Holder").
 
    The  Depositary is a limited-purpose trust  company that was created to hold
securities for its participating organizations (collectively, the "Participants"
or  the  "Depositary's  Participants")  and  to  facilitate  the  clearance  and
settlement  of  transactions  in such  securities  between  Participants through
electronic book-entry changes in accounts of its Participants. The  Depositary's
Participants   include   securities   brokers   and   dealers   (including   the
Underwriters), banks  and trust  companies,  clearing corporations  and  certain
other  organizations. Access  to the  Depositary's system  is also  available to
other  entities   such  as   banks,  brokers,   dealers  and   trust   companies
(collectively,   the  "Indirect  Participants"  or  the  "Depositary's  Indirect
Participants") that clear through  or maintain a  custodial relationship with  a
Participant, either directly or indirectly. Persons who are not Participants may
beneficially  own securities held by or on behalf of the Depositary only through
the Depositary's Participants or the Depositary's Indirect Participants.
 
    The  Company  expects  that  pursuant  to  procedures  established  by   the
Depositary  (i) upon deposit of the Global  Note, the Depositary will credit the
accounts of Participants  designated by  the Underwriters with  portions of  the
principal  amount of the Global Note and  (ii) beneficial ownership of the Notes
evidenced by  the  Global Note  will  be shown  on,  and the  transfer  of  such
ownership  will be effected  only through, records  maintained by the Depositary
(with  respect  to  the  interests   of  the  Depositary's  Participants),   the
Depositary's   Participants   and   the   Depositary's   Indirect  Participants.
Prospective purchasers are  advised that the  laws of some  states require  that
certain  persons take  physical delivery in  definitive form  of securities that
they own. Consequently, the  ability to transfer Notes  evidenced by the  Global
Note will be limited to such extent.
 
    So  long as  the Global Note  Holder is  the registered owner  of the Global
Note, the Global Note Holder will be  considered the sole owner or Holder  under
the  Indenture of any Notes  evidenced by the Global  Note. Beneficial owners of
Notes evidenced by the Global Note will not be considered the owners or  Holders
thereof  under  the Indenture  for any  purpose, including  with respect  to the
giving of
 
                                       69
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any directions, instructions or approvals  to the Trustee thereunder. Except  as
provided  below, owners of beneficial  interests in the Global  Note will not be
entitled to have  Notes registered in  their names  and will not  receive or  be
entitled  to receive physical delivery of  Notes in definitive form. Neither the
Company nor the Trustee will have any responsibility or liability for any aspect
of the records of  the Depositary or for  maintaining, supervising or  reviewing
any records of the Depositary relating to the Notes.
 
    Payments  in respect of the  principal of, premium, if  any, and interest on
any Notes registered in  the name of  the Global Note  Holder on the  applicable
record  date will be payable by the Company to or at the direction of the Global
Note Holder in its capacity as the registered Holder under the Indenture.  Under
the terms of the Indenture, the Company and the Trustee may treat the persons in
whose  names the Notes, including the Global  Note, are registered as the owners
thereof for the purpose  of receiving such  payments. Consequently, neither  the
Company nor the Trustee has or will have any responsibility or liability for the
payment  of such  amounts to beneficial  owners of Notes.  The Company believes,
however, that it is currently the policy of the Depositary to immediately credit
the accounts  of  the  relevant  Participants with  such  payments,  in  amounts
proportionate  to  their  respective  holdings of  beneficial  interests  in the
relevant security as  shown on the  records of the  Depositary. Payments by  the
Depositary's  Participants  and the  Depositary's  Indirect Participants  to the
beneficial owners  of  Notes  will  be governed  by  standing  instructions  and
customary   practice  and  will  be   the  responsibility  of  the  Depositary's
Participants or the Depositary's Indirect Participants.
 
    As long as  the Notes  are represented by  a Global  Note, the  Depositary's
nominee  will be the holder  of the Notes and therefore  will be the only entity
that can exercise  a right  to repayment  or repurchase  of the  Notes. See  "--
Repurchase   at   the   Option   of   Holders   --   Change   of   Control"  and
"-- Asset Sales." Notice  by the Depositary's  Participants or the  Depositary's
Indirect Participants or by owners of beneficial interests in a Global Note held
through such Participants or Indirect Participants of the exercise of the option
to elect repayment of beneficial interests in Notes represented by a Global Note
must  be transmitted to  the Depositary in  accordance with its  procedures on a
form required by the Depositary and provided to Participants. In order to ensure
that the Depositary's  nominee will timely  exercise a right  to repayment  with
respect  to a particular Note,  the beneficial owner of  such Note must instruct
the broker or other Participant or  Indirect Participant through which it  holds
an  interest in such Note  to notify the Depositary of  its desire to exercise a
right  to  repayment.   Different  firms  have   cut-off  times  for   accepting
instructions from their customers and, accordingly, each beneficial owner should
consult the broker or other Participant or Indirect Participant through which it
holds an interest in a Note in order to ascertain the cut-off time by which such
an  instruction must be given in order for  timely notice to be delivered to the
Depositary. The Company will not be liable for any delay in delivery of  notices
of the exercise of the option to elect repayment.
 
    The  Company will issue Notes in definitive  form in exchange for the Global
Note if, and  only if, either  (1) the Depositary  is at any  time unwilling  or
unable  to continue as depositary and a successor depositary is not appointed by
the Company within  90 days,  or (2)  an Event of  Default has  occurred and  is
continuing and the Notes registrar has received a request from the Depositary to
issue  Notes in definitive form in lieu of  all or a portion of the Global Note.
In either instance, an owner of a beneficial interest in the Global Note will be
entitled to have  Notes equal in  principal amount to  such beneficial  interest
registered  in its name and will be  entitled to physical delivery of such Notes
in definitive  form.  Notes so  issued  in definitive  form  will be  issued  in
denominations  of $1,000  and integral multiples  thereof and will  be issued in
registered form only, without coupons.
 
  CERTIFICATED NOTES
 
    If the Company  notifies the Trustee  in writing that  the Depositary is  no
longer  willing or  able to  act as a  depositary and  the Company  is unable to
locate a qualified successor within 90  days then, upon surrender by the  Global
Note Holder of its Global Note, Notes in the form of registered definitive Notes
will  be issued to  each person that  the Global Note  Holder and the Depositary
identify as being the beneficial owner of the related Notes.
 
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<PAGE>
    Neither the Company  nor the Trustee  will be  liable for any  delay by  the
Global  Note Holder  or the Depositary  in identifying the  beneficial owners of
Notes and the  Company and the  Trustee may  conclusively rely on,  and will  be
protected  in  relying  on, instructions  from  the  Global Note  Holder  or the
Depositary for all purposes.
 
  SAME-DAY SETTLEMENT AND PAYMENT
 
    The Indenture will require that payments in respect of the Notes represented
by the Global Note  (including principal, premium, if  any, interest be made  by
wire  transfer of immediately  available funds to the  accounts specified by the
Global Note Holder. With  respect to Certificated Notes,  the Company will  make
all  payments  of  principal, premium,  if  any,  interest by  wire  transfer of
immediately available funds to the accounts specified by the Holders thereof or,
if no  such account  is specified,  by mailing  a check  to each  such  Holder's
registered  address.  Secondary trading  in  long-term notes  and  debentures of
corporate issuers is generally settled  in clearinghouse or next-day funds.  The
Company  expects that secondary  trading in the Certificated  Notes will also be
settled in immediately available funds.
 
GOVERNING LAW
 
    The Indenture, the Notes and the Subsidiary Guarantees will be governed  by,
and construed in accordance with, the laws of the State of New York.
 
CERTAIN DEFINITIONS
 
    Set  forth below are certain defined  terms used in the Indenture. Reference
is made to the Indenture for a full disclosure of all such terms, as well as any
other capitalized terms used herein for which no definition is provided.
 
    "ACQUIRED INDEBTEDNESS" means with respect to any specified Person, (i)  any
Indebtedness  of any  other Person  existing at  the time  such other  Person is
merged with or into or becomes a Subsidiary of such specified Person, including,
without  limitation,   Indebtedness  incurred   in   connection  with,   or   in
contemplation  of,  such  other  Person  merging  with  or  into  or  becoming a
Subsidiary of such  specified Person, and  (ii) Indebtedness secured  by a  Lien
encumbering any asset acquired by such specified Person.
 
    "ADJUSTED  CONSOLIDATED  NET  TANGIBLE  ASSETS" means,  as  of  the  date of
determination, without duplication,  (a) the  sum of (i)  discounted future  net
revenue  from proved oil  and gas reserves  of the Company  and its Subsidiaries
calculated in accordance with Commission guidelines before any state or  federal
income  taxes, as estimated  in a reserve report  prepared as of  the end of the
Company's most recently completed fiscal year, which reserve report is  prepared
or  audited by independent petroleum engineers, as  increased by, as of the date
of determination, the discounted future net revenue of (A) estimated proved  oil
and  gas  reserves  of the  Company  and  its Subsidiaries  attributable  to any
acquisition consummated since the date of such year-end reserve report, and  (B)
estimated oil and gas reserves of the Company and its Subsidiary attributable to
extensions, discoveries and other additions and upward revisions of estimates of
proved  oil  and gas  reserves  due to  exploration,  development, exploitation,
production or other activities conducted  or otherwise occurring since the  date
of  such year-end reserve report which would, in the case of determinations made
pursuant to clauses (A) and (B), in accordance with standard industry  practice,
result  in such  additions or revisions,  in each case  calculated in accordance
with Commission  guidelines  (utilizing the  prices  utilized in  such  year-end
reserve  report),  and  decreased  by,  as of  the  date  of  determination, the
discounted future net revenue  of (C) estimated proved  oil and gas reserves  of
the  Company and its Subsidiaries produced or disposed of since the date of such
year-end reserve report and (D) reductions in the estimated oil and gas reserves
of the Company  and its  Subsidiaries since the  date of  such year-end  reserve
report  attributable to  downward revisions of  estimates of proved  oil and gas
reserves due  to exploration,  development,  exploitation, production  or  other
activities  conducted or  otherwise occurring  since the  date of  such year-end
reserve report  which would,  in the  case of  determinations made  pursuant  to
clauses  (C) and (D),  in accordance with standard  industry practice, result in
such revisions, in each case calculated in accordance with Commission guidelines
(utilizing the prices utilized in such year-end reserve report); provided  that,
in  the case of each of the  determinations made pursuant to clauses (A) through
(D),
 
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such increases and decreases shall be  as estimated by the Company's  engineers,
except  that if  as a  result of  such acquisitions,  dispositions, discoveries,
extensions or revisions, there  is a Material Change  that is an increase,  then
such  increases  and decreases  in the  discounted future  net revenue  shall be
confirmed in writing  by independent petroleum  engineers, (ii) the  capitalized
costs  that are attributable  to oil and  gas properties of  the Company and its
Subsidiaries to which no  proved oil and gas  reserves are attributed, based  on
the  Company's books and  records as of a  date no earlier than  the date of the
Company's latest annual or quarterly financial statements, (iii) the net working
capital (which shall be calculated as all current assets of the Company and  its
Subsidiaries  minus all current liabilities of the Company and its Subsidiaries,
except current liabilities included  in Indebtedness on a  date no earlier  than
the  date of the Company's latest  annual or quarterly financial statements) and
(iv) the greater of (I) the net book  value of the other tangible assets of  the
Company and its Subsidiaries on a date no earlier than the date of the Company's
latest annual or quarterly financial statements and (II) the appraised value, as
estimated by independent appraisers, of other tangible assets of the Company and
its  Subsidiaries as of a date no earlier  than the date of the Company's latest
audited financial statements,  MINUS (b) the  sum of (i)  minority interests  of
third  parties  to the  extent included  in the  calculation of  the immediately
preceding  clause  (a),  (ii)  the  positive  remainder,  if  any,  obtained  by
subtracting  (I) gas balancing underpayments of the Company and its Subsidiaries
reflected in the Company's latest audited financial statements and not otherwise
included in the calculation  of the immediately preceding  clause (a) from  (II)
any  gas balancing liabilities of the  Company and its Subsidiaries reflected in
the Company's latest audited financial statements and not otherwise included  in
the  calculation  of  the  immediately  preceding  clause  (a),  and  (iii)  the
discounted  future  net  revenue,  calculated  in  accordance  with   Commission
guidelines (utilizing the same prices utilized in the Company's year-end reserve
report),   attributable  to  oil  and  gas  reserves  of  the  Company  and  its
Subsidiaries subject to participation interests, overriding royalty interests or
other interests of third parties, pursuant to participation, partnership, vendor
financing or other agreements then in effect, other than pursuant to  Production
Payments, or that otherwise are required to be delivered to third parties, other
than pursuant to Production Payments.
 
    "ADJUSTED  CONSOLIDATED  NET  TANGIBLE ASSETS  TO  CONSOLIDATED INDEBTEDNESS
RATIO" means,  at any  time, the  ratio of  Adjusted Consolidated  Net  Tangible
Assets at such time to Consolidated Indebtedness at such time.
 
    "AFFILIATE"  of any specified Person means  (i) any other Person directly or
indirectly controlling  or controlled  by  or under  direct or  indirect  common
control with such specified Person or (ii) any other Person who is a director or
executive  officer of (a) such  specified Person or (b)  any Person described in
the preceding clause (i). For purposes of this definition, "control" (including,
with correlative meanings, the terms  "controlling," "controlled by" and  "under
common  control  with"), as  used with  respect  to any  Person, shall  mean the
possession, directly  or  indirectly,  of  the power  to  direct  or  cause  the
direction  of the  management or  policies of  such Person,  whether through the
ownership of  voting  securities,  by  agreement  or  otherwise;  PROVIDED  that
beneficial ownership of 10% or more of any class, or any series of any class, of
equity  securities of  a Person, whether  or not  voting, shall be  deemed to be
control.
 
    "ASSET SALE" means with respect to  any Person, the sale, lease,  conveyance
or  other  disposition, that  does  not constitute  a  Restricted Payment  or an
Investment, by such Person of any of its assets (including, without  limitation,
by  way  of a  Sale  and Leaseback  and including  the  issuance, sale  or other
transfer of any Equity Interests in any Subsidiary or the sale or other transfer
of any Equity  Interests in any  Unrestricted Subsidiary of  such Person)  other
than  to the  Company (including  the receipt of  proceeds of  insurance paid on
account of the loss of or damage to any asset and awards of compensation for any
asset taken by condemnation, eminent domain or similar proceeding, and including
the receipt of proceeds  of business interruption insurance),  in each case,  in
one  or a  series of  related transactions;  PROVIDED that,  notwithstanding the
foregoing, the  term  "Asset Sale"  shall  not  include: (a)  the  sale,  lease,
conveyance,  disposition or  other transfer of  all or substantially  all of the
assets of the Company, as permitted  pursuant to the covenant entitled  "Merger,
Consolidation or Sale
 
                                       72
<PAGE>
   
of  Assets," (b) the sale or lease of hydrocarbons or other mineral interests in
the ordinary course of business and customary  in the Oil and Gas Business,  (c)
any  Production Payment,  (d) a transfer  of assets  by the Company  to a Wholly
Owned Subsidiary of the  Company (other than any  Principal Properties) or by  a
Wholly Owned Subsidiary of the Company to the Company or to another Wholly Owned
Subsidiary of the Company, (e) an issuance of Equity Interests by a Wholly Owned
Subsidiary  of the Company to the Company  or to another Wholly Owned Subsidiary
of the Company, (e) sale  or other disposition of  cash or Cash Equivalents,  or
(f)  any lease, abandonment, disposition, relinquishment  or farm out of any oil
and gas property  that are  customary in  nature and scope  in the  Oil and  Gas
Business and are entered into in the ordinary course of the Oil and Gas Business
of the Company and its Subsidiaries.
    
 
    "BENEFICIARY",  when used with respect to  any individual, means the spouse,
lineal descendants, parents and siblings of any such individual, the estates and
the legal representatives of  any such individual and  any of the foregoing  and
the  trustee of any bona fide trust of  which any such individual and any of the
foregoing are the sole beneficiaries or grantors.
 
    "CAPITAL LEASE OBLIGATION" means, at  the time any determination thereof  is
to be made, the amount of the liability in respect of a capital lease that would
at such time be required to be capitalized on a balance sheet in accordance with
GAAP.
 
    "CAPITAL  STOCK" means (i) in the case of a corporation, capital stock, (ii)
in the case of an association or business entity, any and all shares, interests,
participations, rights  or other  equivalents  (however designated)  of  capital
stock,  (iii) in the case of partnership, partnership interests (whether general
or limited)  and (iv)  any other  interest or  participation that  confers on  a
Person  the  right  to  receive  a  share  of  the  profits  and  losses  of, or
distributions of assets of, the issuing Person.
 
    "CASH  EQUIVALENT"  means  (a)  securities  issued  or  directly  and  fully
guaranteed  or  insured  by  the  United States  of  America  or  any  agency or
instrumentality thereof (provided that the full  faith and credit of the  United
States  is pledged  in support thereof)  having maturities not  more than twelve
months from the  date of acquisition,  (b) U.S. dollar  denominated (or  foreign
currency  fully hedged) time deposits,  certificates of deposit, Eurodollar time
deposits or Eurodollar certificates  of deposit of  (i) any domestic  commercial
bank of recognized standing having capital and surplus in excess of $500 million
or  (ii) any bank whose short-term commercial  paper rating from S&P is at least
A-1 or the equivalent thereof or from Moody's is at least P-1 or the  equivalent
thereof (any such bank being an "Approved Lender"), in each case with maturities
of  not more than twelve months from the date of acquisition, and (c) commercial
paper issued by any Approved  Lender (or by the  parent company thereof) or  any
variable  rate notes issued by, or guaranteed by, any domestic corporation rated
A-1 (or the  equivalent thereof)  or better  by S&P  or P-1  (or the  equivalent
thereof)  or better by Moody's and maturing  within twelve months of the date of
acquisition.
 
    "CHANGE OF CONTROL" means such time as any of the following events occur:
 
        (i) any "person" or  "group" (as such terms  are used in Sections  13(d)
    and  14(d) of the  Exchange Act), other  than Cadell S.  Liedtke, Michael J.
    Grella and Henry G. Musselman and any of their respective Beneficiaries (the
    "Approved Shareholders), is or becomes the "beneficial owner" (as defined in
    Rule 13d-3 under the Exchange Act), directly or indirectly, of more than 50%
    of the total Voting Stock of the Company;
 
        (ii) the Company  is merged with  or into or  consolidated with  another
    Person  and, immediately after giving effect to the merger or consolidation,
    (A) less than 50% of the total voting power of the outstanding Voting  Stock
    of  the surviving or  resulting Person is  then "beneficially owned" (within
    the meaning of Rule 13d-3  under the Exchange Act)  in the aggregate by  the
    stockholders   of  the   Company  immediately   prior  to   such  merger  or
    consolidation, and  (B)  any "person"  or  "group" (as  defined  in  Section
    13(d)(3)   or  14(d)(2)  of  the  Exchange  Act)  other  than  the  Approved
 
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<PAGE>
    Stockholders has  become  the  direct or  indirect  "beneficial  owner"  (as
    defined  in Rule 13d-3 under the Exchange Act) of more than 50% of the total
    voting power of the Voting Stock of the surviving or resulting Person;
 
        (iii) the Company,  either individually  or in conjunction  with one  or
    more  Subsidiaries, sells, assigns, conveys,  transfers, leases or otherwise
    disposes of, or the  Subsidiaries sell, assign,  convey, transfer, lease  or
    otherwise  dispose of,  all or  substantially all  of the  properties of the
    Company and the Subsidiaries, taken as a whole (either in one transaction or
    a  series  of  related  transactions),   including  Capital  Stock  of   the
    Subsidiaries,  to  any Person  (other  than the  Company  or a  Wholly Owned
    Subsidiary);
 
        (iv) during  any consecutive  two-year period,  individuals who  at  the
    beginning  of such period constituted the  Board of Directors of the Company
    (together with any new directors whose  election by such Board of  Directors
    or  whose nomination  for election  by the  stockholders of  the Company was
    approved by a vote of a majority  of the directors then still in office  who
    were  either directors at the beginning of  such period or whose election or
    nomination for election was previously so approved) cease for any reason  to
    constitute  a majority  of the  Board of  Directors of  the Company  then in
    office; or
 
        (v) the liquidation or dissolution of the Company.
 
   
    "CONSOLIDATED EBITDA" means, with respect to any Person for any period,  the
sum  of, without duplication, (i) the Consolidated Net Income of such Person and
its Subsidiaries  for such  period, plus  (ii)  to the  extent deducted  in  the
computation  of such Consolidated Net  Income, the Consolidated Interest Expense
for such period, plus (iii)  to the extent deducted  in the computation of  such
Consolidated  Net Income,  amortization of  deferred financing  charges for such
period, plus (iv) provision for taxes based on income or profits for such period
(to the extent such  income or profits were  included in computing  Consolidated
Net  Income for such period), plus (v) to the extent deducted in the computation
of  such  Consolidated   Net  Income,   consolidated  depreciation,   depletion,
amortization  and  other noncash  charges of  such  Person and  its Subsidiaries
required to be reflected as  expenses on the books  and records of such  Person,
plus  (vi) to the  extent deducted in  the computation of  such Consolidated Net
Income, consolidated exploration and abandonment expenses of such Person and its
Subsidiaries for such  periods, minus (vii)  cash payments with  respect to  any
nonrecurring,  noncash charges previously added back pursuant to clause (v), and
excluding (viii) the  impact of foreign  currency translations.  Notwithstanding
the  foregoing, the provision for  taxes based on the  income or profits of, and
the depreciation  and  amortization  and  other  noncash  charges  of,  and  the
exploration and abandonment expenses of, a Subsidiary of a Person shall be added
to  Consolidated Net  Income to compute  Consolidated EBITDA only  to the extent
(and in the same proportion) that the Net Income of such Subsidiary was included
in calculating  the  Consolidated  Net Income  of  such  Person and  only  if  a
corresponding  amount  would be  permitted at  the date  of determination  to be
dividended to such Person by such Subsidiary without prior approval (unless such
approval has  been obtained),  pursuant to  the  terms of  its charter  and  all
agreements,   instruments,  judgments,  decrees,  orders,  statutes,  rules  and
governmental regulations applicable to that Subsidiary or its stockholders.
    
 
    "CONSOLIDATED INDEBTEDNESS" means, with respect to any Person for any  time,
the  Indebtedness of such Person and its Subsidiaries at such time as determined
on a consolidated basis in accordance with GAAP.
 
    "CONSOLIDATED INTEREST COVERAGE RATIO" means with respect to any Person  for
any  period,  the  ratio of  (i)  Consolidated  EBITDA of  such  Person  and its
Subsidiaries for  such period  to  (ii) Consolidated  Interest Expense  of  such
Person  and its Subsidiaries for  such period. In the  event that the Company or
any of its  Subsidiaries incurs, assumes,  Guarantees or repays  or redeems  any
Indebtedness  (other  than revolving  credit  borrowings) or  issues  or redeems
preferred stock subsequent  to the  commencement of  the four-quarter  reference
period  for which the  Consolidated Interest Coverage  Ratio is being calculated
but on or prior to the date on which the event for which the calculation of  the
Consolidated  Interest Coverage Ratio is made (the "Calculation Date"), then the
 
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Consolidated Interest Coverage Ratio shall be calculated giving pro forma effect
to  such  incurrence,   assumption,  Guarantee,  repayment   or  redemption   of
Indebtedness,  or such issuance or redemption of preferred stock, as if the same
had occurred at the beginning  of the applicable four-quarter reference  period.
For  purposes of making the computation referred to above, (i) acquisitions that
have been made  by the  Company or any  of its  Subsidiaries, including  through
mergers  or  consolidations and  including  any related  financing transactions,
during the four-quarter reference period or subsequent to such reference  period
and  on or prior to the Calculation Date shall be deemed to have occurred on the
first day of the four-quarter reference period, and (ii) the Consolidated EBITDA
attributable to discontinued operations, as determined in accordance with  GAAP,
and operations or businesses disposed of prior to the Calculation Date, shall be
excluded,   and  (iii)   the  Consolidated  Interest   Expense  attributable  to
discontinued operations, as determined in  accordance with GAAP, and  operations
or  businesses disposed of prior to the Calculation Date, shall be excluded, but
only to  the  extent that  the  obligations  giving rise  to  such  Consolidated
Interest  Expense will not be  obligations of the referent  Person or any of its
Subsidiaries following the Calculation Date.
 
   
    "CONSOLIDATED INTEREST EXPENSE" means,  with respect to  any Person for  any
period,  the sum, without duplication, of  (i) the consolidated interest expense
of  such  Person  and  its  Subsidiaries  for  such  period  including,  without
limitation,  amortization of original issue discount, noncash interest payments,
the interest  component  of  any  deferred  payment  obligations,  the  interest
component   of  all   payments  associated   with  Capital   Lease  Obligations,
commissions, discounts and other fees and charges incurred in respect of  letter
of  credit or bankers' acceptance financings, and net payments (if any) pursuant
to Hedging  Obligations, but  excluding amortization  or write-off  of  deferred
financing charges for such period, and (ii) the consolidated interest expense of
such  Person and its  Subsidiaries that was capitalized  during such period, and
(iii) any interest expense on Indebtedness of another Person that is  Guaranteed
by such Person or one of its Subsidiaries or secured by a Lien on assets of such
Person  or one  of its Subsidiaries  (whether or  not such Guarantee  or Lien is
called upon),  and (iv)  the product  of  (a) all  cash dividend  payments  (and
noncash  dividend payments in the case of a  Person that is a Subsidiary) on any
series of preferred  stock of  such Person  payable to  a party  other than  the
Company  or a Wholly  Owned Subsidiary, times  (b) a fraction,  the numerator of
which is one and the denominator of which is one minus the then current combined
federal, state  and local  statutory tax  rate of  such Person,  expressed as  a
decimal, on a consolidated basis and in accordance with GAAP.
    
 
    "CONSOLIDATED  NET INCOME" means, with respect to any Person for any period,
the aggregate of the  Net Income of  such Person and  its Subsidiaries for  such
period,  on a consolidated  basis, determined in  accordance with GAAP; provided
that (i) the Net Income (but not loss) of any Person that is not a Subsidiary or
that is accounted for by the equity method of accounting shall be included  only
to  the extent of the  amount of dividends or distributions  paid in cash to the
referent Person or a Wholly Owned Subsidiary thereof, (ii) the Net Income of any
Subsidiary shall be excluded  to the extent that  the declaration or payment  of
dividends  or similar distributions by that Subsidiary of that Net Income is not
at the date of determination  permitted without any prior governmental  approval
(unless  such  approval  has  been  obtained)  or,  directly  or  indirectly, by
operation of the terms  of its charter or  any agreement, instrument,  judgment,
decree,  order,  statute, rule  or  governmental regulation  applicable  to that
Subsidiary or its stockholders, (iii) the Net Income of any Person acquired in a
pooling of  interests transaction  for any  period  prior to  the date  of  such
acquisition  shall  be  excluded, (iv)  the  cumulative  effect of  a  change in
accounting principles  shall be  excluded and  (v)  the Net  Income of,  or  any
dividends  or  other distributions  from,  any Unrestricted  Subsidiary,  to the
extent otherwise included, shall be excluded  unless distributed in cash to  the
Company or one of its Subsidiaries.
 
    "CONSOLIDATED  NET WORTH" means, with respect to  any Person as of any date,
the consolidated  stockholders'  equity  of such  Person  and  its  consolidated
Subsidiaries  as of such date  less (w) the amount  of such stockholders' equity
attributable to Disqualified Stock, (x) all write-ups subsequent to the date  of
the  Indenture  in  the book  value  of any  asset  owned  by such  Person  or a
consolidated  Subsidiary  of  such   Person  (other  than  purchase   accounting
adjustments made, in connection with any
 
                                       75
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acquisition  of any entity that becomes a consolidated Subsidiary of such Person
after the date of the Indenture to the book value of the assets of such entity),
(y) all  investments as  of  such date  in  unconsolidated Subsidiaries  and  in
Persons that are not Subsidiaries (except, in each case, Permitted Investments),
and  (z)  all unamortized  debt discount  and  expense and  unamortized deferred
charges as of  such date,  all of the  foregoing determined  in accordance  with
GAAP.
 
   
    "CREDIT FACILITY" means a credit facility that may be entered into among the
Company  and  the lenders  parties thereto  (which shall  initially be  a credit
facility among the Company, NationsBank of Texas, N.A. or one of its affiliates,
as agent, and the other lenders  parties thereto), including any related  notes,
guarantees,   collateral  documents,  instruments  and  agreements  executed  in
connection therewith, and in each case as amended, modified, renewed,  extended,
refunded, replaced, restated or refinanced from time to time.
    
 
    "DEFAULT"  means any event that is or with the passage of time or the giving
of notice or both would be an Event of Default.
 
    "DESIGNATED GUARANTOR SENIOR INDEBTEDNESS" means  (i) so long as the  Senior
Bank  Indebtedness is  outstanding, any  Subsidiary Guarantor's  Indebtedness in
respect of the Senior Bank Indebtedness and (ii) thereafter, any other Guarantor
Senior Indebtedness permitted under the Indenture the principal amount of  which
is  $15.0  million  or more  and  that has  been  designated by  the  Company as
"Designated Guarantor Senior Indebtedness."
 
    "DESIGNATED SENIOR  INDEBTEDNESS"  means (i)  so  long as  the  Senior  Bank
Indebtedness  is outstanding, the Senior  Bank Indebtedness and (ii) thereafter,
any other Senior Indebtedness permitted under the Indenture the principal amount
of which is $15.0 million or more and that has been designated by the Company as
"Designated Senior Indebtedness"; provided  that for purposes  of clause (i)  of
the  first sentence  of the third  paragraph under  the caption "Subordination,"
"Designated Senior Indebtedness" shall also  mean any other Senior  Indebtedness
permitted  under the Indenture the principal amount of which is $15.0 million or
more.
 
    "DISQUALIFIED STOCK" means (a) with respect to any Person, Capital Stock  of
such Person that, by its terms (or by the terms of any security into which it is
convertible or for which it is exchangeable), or upon the happening of any event
(unless  any redemption or repurchase of  such Capital Stock upon the occurrence
of such event  is required  by any such  terms, but  only to the  extent that  a
payment in respect thereof would be permitted under the covenant set forth under
the  caption  "Restricted  Payments"),  matures  or  is  mandatorily redeemable,
pursuant to a  sinking fund  obligation or otherwise,  or is  redeemable at  the
option of the Holder thereof, in whole or in part, on or prior to the date which
is one year after the date on which the Notes mature and (b) with respect to any
Subsidiary  of  such Person  (including with  respect to  any Subsidiary  of the
Company), any Capital  Stock other  than any  common stock  with no  preference,
privileges, or redemption or repayment provisions.
 
    "DOLLAR-DENOMINATED  PRODUCTION  PAYMENTS" mean  dollar  denominated payment
obligations of the  Company or any  of its  Subsidiaries that are  or, upon  the
occurrence of a contingent event, would be recorded as liabilities in accordance
with  GAAP, together with all undertakings and obligations of the Company or any
of its Subsidiaries in connection therewith, which obligations will be deemed to
constitute Indebtedness for borrowed money for purposes of the Indenture.
 
    "EQUITY INTERESTS" means Capital  Stock and all  warrants, options or  other
rights  to  acquire  Capital Stock  (but  excluding  any debt  security  that is
convertible into, or exchangeable for, Capital Stock), whether outstanding prior
to, on or after the date of the Indenture.
 
    "EQUITY OFFERING" means an offer and sale of Qualified Stock of the  Company
to a Person other than an Affiliate of the Company.
 
    "EXCHANGE ACT" means the Securities Exchange Act of 1934, as amended.
 
    "EXEMPT  AFFILIATE TRANSACTIONS" means (a) transactions between or among the
Company and/or  its  Wholly  Owned  Subsidiaries, (b)  advances  not  to  exceed
$1,000,000 at any time outstanding to
 
                                       76
<PAGE>
officers  of the Company or any Subsidiary of the Company in the ordinary course
of business to provide for the  payment of reasonable expenses incurred by  such
persons  in the  performance of  their responsibilities  to the  Company or such
Subsidiary or in connection with any relocation, (c) fees and compensation  paid
to  and indemnity provided on behalf of  directors, officers or employees of the
Company or any Subsidiary of the Company in the ordinary course of business, (d)
any employment agreement that is in effect  on the date of the Indenture in  the
ordinary  course of business and any such  agreement entered into by the Company
or a  Subsidiary after  the date  of the  Indenture in  the ordinary  course  of
business  of the  Company or such  Subsidiary and (e)  payments and transactions
under the Indebtedness  of A&P  Meter Service and  Supply, Inc.  ("A&P") to  the
Company  outstanding on  the date  of the Indenture  and the  performance of and
payment for services provided by A&P to the Company and its Subsidiaries in  the
ordinary  course  of  business  consistent  with  past  practice.  See  "Certain
Transactions."
 
    "GAAP" means  generally  accepted accounting  principles  set forth  in  the
opinions  and pronouncements of the Accounting  Principles Board of the American
Institute of Certified Public Accountants  and statements and pronouncements  of
the  Financial Accounting  Standards Board or  in such other  statements by such
other entity as have  been approved by a  significant segment of the  accounting
profession, which are in effect on the date of the Indenture.
 
    "GUARANTEE"  means  a guarantee  (other  than by  endorsement  of negotiable
instruments for  collection  in the  ordinary  course of  business),  direct  or
indirect,  in any manner  (including, without limitation,  letters of credit and
reimbursement agreements  in  respect  thereof),  of all  or  any  part  of  any
Indebtedness.
 
    "GUARANTOR   SENIOR  INDEBTEDNESS"   means  (i)  all   Guarantees  or  other
Indebtedness  of  a  Subsidiary  Guarantor   in  respect  of  the  Senior   Bank
Indebtedness  and  (ii) any  other indebtedness  permitted to  be incurred  by a
Subsidiary Guarantor under the  terms of this  Indenture, unless the  instrument
under  which  such  Indebtedness  is  incurred  expressly  provides  that  it is
subordinated in  right  of  payment  to any  Indebtedness  for  money  borrowed.
Notwithstanding  anything  to the  contrary in  the foregoing,  Guarantor Senior
Indebtedness will not  include (w) any  liability for federal,  state, local  or
other  taxes owed or owing by a  Subsidiary Guarantor, (x) any Indebtedness of a
Subsidiary  Guarantor  to  any  of  the  Company's  Subsidiaries,   Unrestricted
Subsidiaries or other Affiliates, (y) any trade payables or (z) any Indebtedness
that is incurred in violation of this Indenture.
 
    "HEDGING  OBLIGATIONS" means, with respect to any Person, the obligations of
such  Person  under  (i)  interest  rate  swap  agreements,  interest  rate  cap
agreements  and interest  rate collar  agreements and  (ii) other  agreements or
arrangements designed  to  protect  such  Person  against  fluctuations  in  (a)
interest rates, (b) the value of foreign currencies and (c) Oil and Gas Purchase
and Sales Contracts.
 
    "INDEBTEDNESS"  means, with respect to  any Person, without duplication, (a)
all liabilities of such Person for  borrowed money or for the deferred  purchase
price  of property or  services (excluding any trade  accounts payable and other
accrued current liabilities incurred  in the ordinary  course of business),  and
all  liabilities  of such  Person  incurred in  connection  with any  letters of
credit, bankers'  acceptances  or  other  similar  credit  transactions  or  any
agreement  to purchase, redeem, exchange, convert or otherwise acquire for value
any Capital Stock of such Person, or any warrants, rights or options to  acquire
such  Capital Stock outstanding on the date  of the Indenture or thereafter, if,
and to the  extent, any  of the  foregoing would appear  as a  liability upon  a
balance  sheet  of  such  Person  prepared  in  accordance  with  GAAP,  (b) all
obligations of  such  Person evidenced  by  bonds, notes,  debentures  or  other
similar instruments, if, and to the extent, any of the foregoing would appear as
a  liability upon  a balance  sheet of such  Person prepared  in accordance with
GAAP, (c)  all  Indebtedness  of  such  Person  created  or  arising  under  any
conditional  sale or  other title retention  agreement with  respect to property
acquired by such Person (even if the rights and remedies of the seller or lender
under such agreement in the event of default are limited to repossession or sale
of such property), but excluding trade accounts payable arising in the  ordinary
course  of business, (d)  all Capitalized Lease Obligations  of such Person, (e)
all  Indebtedness  referred  to  in  the  preceding  clauses  of  other  Persons
 
                                       77
<PAGE>
and  all dividends of other Persons, the payment  of which is secured by (or for
which the holder of such  Indebtedness has an existing  right to be secured  by)
any  Lien upon  property (including,  without limitation,  accounts and contract
rights) owned by such Person, even though such Person has not assumed or  become
liable for the payment of such Indebtedness (the amount of such obligation being
deemed  to be the lesser of the value of such property or asset or the amount of
the obligation so secured) (f) all  Production Payments of such Person, (g)  all
guarantees  by such Person  of Indebtedness referred to  in this definition, (h)
all Disqualified Stock of such Person valued at the greater of its voluntary  or
involuntary  maximum fixed repurchase  price plus accrued  dividends and (i) all
obligations of such Person under or  in respect to currency exchange  contracts,
oil  or  natural gas  price hedging  arrangements  and Hedging  Obligations. For
purposes hereof,  the "maximum  fixed repurchase  price" of  Disqualified  Stock
which  does not have a fixed repurchase  price shall be calculated in accordance
with the  terms  of  such  Disqualified Stock  as  if  Disqualified  Stock  were
purchased  on any date on which Indebtedness  shall be required to be determined
pursuant to the Indenture, and if such price is based upon, or measured by,  the
fair  market value of such  Disqualified Stock, such fair  market value shall be
determined in  good faith  by  the board  of directors  of  the issuer  of  such
Disqualified Stock; provided, however, that if such Disqualified Stock is not at
the  date of determination permitted or  required to be repurchase, the "maximum
fixed repurchase price" shall be the book value of such Disqualified Stock.
 
    "INVESTMENTS" means, with  respect to  any Person, all  investments by  such
Person in other Persons (including Affiliates) in the form of direct or indirect
loans  (including guarantees of Indebtedness  or other obligations), advances or
capital contributions (excluding advances to officers and employees of the  type
specified  in clause  (b) of the  definition of  Exempt Affiliate Transactions),
purchases or  other  acquisitions  for  consideration  of  Indebtedness,  Equity
Interests  or  other  securities  and  all other  items  that  are  or  would be
classified as investments on  a balance sheet prepared  in accordance with  GAAP
and  the acquisition, by purchase  or otherwise, of all  or substantially all of
the business or assets of any other Person.
 
    "LIEN" means, with respect to any asset, any mortgage, lien, pledge, charge,
security interest or encumbrance of any  kind in respect of such asset,  whether
or  not filed, recorded  or otherwise perfected  under applicable law (including
any conditional sale or other title retention agreement, any lease in the nature
thereof, any option or other  agreement to sell or  give a security interest  in
and any filing of or agreement to give any financing statement under the Uniform
Commercial Code (or equivalent statutes) of any jurisdiction).
 
    "MATERIAL  CHANGE"  means an  increase or  decrease (excluding  changes that
result solely from changes in prices) of  more than 10% during a fiscal  quarter
in  the discounted future net cash flows from proved oil and gas reserves of the
Company and its Subsidiaries calculated in accordance with clause (a)(i) of  the
definition of Adjusted Consolidated Net Tangible Assets; PROVIDED, however, that
the  following will be excluded from the calculation of Material Change: (i) any
acquisition during the quarter of oil and gas reserves that have been  estimated
by  independent petroleum engineers and on which  a report or reports exists and
(ii) any disposition  of properties existing  at the beginning  of such  quarter
that have been disposed of pursuant to the provisions of the Indenture described
under the caption "Redemption of the Option of the Holders."
 
   
    "NET  INCOME" means, with  respect to any  Person, the net  income (loss) of
such Person, determined  in accordance  with GAAP  and before  any reduction  in
respect  of preferred stock dividends, excluding, however, (i) any gain (but not
loss, except as provided in (b) below), together with any related provision  for
taxes  on such gain  (but not loss),  realized in connection  with (a) any Asset
Sale (including, without limitation, dispositions pursuant to Sale and Leaseback
transactions) or (b) the disposition of any securities by such Person or any  of
its  Subsidiary or the extinguishment of any  Indebtedness of such Person or any
of its Subsidiary,  other than  any loss arising  out of  the extinguishment  of
Indebtedness  refinanced with  the proceeds  of the  Notes and  other securities
issued contemporaneously with the Notes, (ii) any extraordinary or  nonrecurring
gain (but not loss, except as provided
    
 
                                       78
<PAGE>
   
in   (i)  above),  together  with  any  related  provision  for  taxes  on  such
extraordinary or nonrecurring gain (but not  loss), and (iii) any gain (but  not
loss) from currency exchange transactions not in the ordinary course of business
consistent with past practice.
    
 
    "NET  PROCEEDS" means the aggregate cash proceeds received by the Company or
any of  its  Subsidiaries in  respect  of  any Asset  Sale  (including,  without
limitation,  any cash received upon the sale or other disposition of any noncash
consideration received in any Asset Sale),  net of the direct costs relating  to
such Asset Sale (including, without limitation, legal, accounting and investment
banking  fees, and sales commissions) and  any relocation expenses incurred as a
result thereof, taxes paid or payable as  a result thereof, and any reserve  for
adjustment  in respect of the sale price  of such asset or assets established in
accordance with GAAP.
 
    "NON-RECOURSE INDEBTEDNESS" means Indebtedness (i)  as to which neither  the
Company  nor any  of its  Subsidiaries (a) provides  credit support  of any kind
(including any  undertaking,  agreement  or  instrument  that  would  constitute
Indebtedness),  (b)  is  directly  or  indirectly  liable  (as  a  guarantor  or
otherwise), or (c) constitutes the lender;  and (ii) no default with respect  to
which  (including  any  rights  that  the  holders  thereof  may  have  to  take
enforcement action  against  an  Unrestricted  Subsidiary)  would  permit  (upon
notice,  lapse of  time or  both) any  holder of  any other  Indebtedness of the
Company or  any  of  its  Subsidiaries  to  declare  a  default  on  such  other
Indebtedness  or cause the payment thereof to be accelerated or payable prior to
its stated maturity.
 
    "OBLIGATIONS"   means    any   principal,    interest,   penalties,    fees,
indemnifications,  reimbursements, damages  and other  liabilities payable under
the documentation governing any Indebtedness.
 
    "OIL AND  GAS BUSINESS"  means  the business  of  the exploration  for,  and
development,   acquisition,  and  production   of  hydrocarbons,  together  with
activities  ancillary  thereto  (including   with  limitation,  the   gathering,
processing,  treatment,  marketing and  transportation  of such  production) and
other related energy and natural resources businesses.
 
    "OIL AND GAS PURCHASE AND SALE  CONTRACT" means with respect to any  Person,
any  oil  and  gas  agreements  and  other  agreements  or  arrangements  or any
combination thereof  entered into  by  such Person  in  the ordinary  course  of
business  and that is designed to provide protection against oil and natural gas
price fluctuations.
 
    "PERMITTED INVESTMENTS" means (a) any Investments by the Subsidiaries of the
Company in the Company; (b) any Investments in Cash Equivalents; (c) Investments
made as a result of the receipt of noncash consideration from an Asset Sale that
was made pursuant to and in  compliance with the covenant described above  under
the  caption  "Repurchase  at  the  Option  of  Holders  --  Asset  Sales";  (d)
Investments outstanding as  of the  date of  the Indenture;  (e) Investments  in
Wholly Owned Subsidiaries engaged in the Oil and Gas Business and Investments in
any  Person that, as a  result of such Investment  (or a series of substantially
contemporaneous Investments  made pursuant  to  a single  plan) (x)  such  other
Person  becomes a Wholly Owned Subsidiary engaged in the Oil and Gas Business or
(y) such other Person that is engaged in  the Oil and Gas Business is merged  or
consolidated  with or into, or transfers or  conveys all or substantially all of
its assets  to  the  Company or  a  Wholly  Owned Subsidiary  in  a  transaction
permitted  under  the  Indenture;  (f) entry  into  operating  agreements, joint
ventures, partnership agreements, working interests, royalty interests,  mineral
leases,  processing  agreements, farm-out  agreements,  contracts for  the sale,
transportation or  exchange  of oil  and  natural gas,  unitization  agreements,
pooling  arrangements, area  of mutual interest  agreements or  other similar or
customary agreements, transactions, properties,  interests or arrangements,  and
Investments  and expenditures  in connection  therewith or  pursuant thereto, in
each case  made or  entered into  in  the ordinary  course of  the Oil  and  Gas
Business,  excluding, however, Investments  in corporations; (g)  entry into any
hedging arrangements  in the  ordinary course  of business  for the  purpose  of
protecting  the Company's or any  Subsidiaries's production against fluctuations
in oil or natural gas prices; (h) shares of money mutual or similar funds having
assets in excess of $500,000,000, and (i) Investments in an aggregate amount not
to exceed $5,000,000 at any one time outstanding.
 
                                       79
<PAGE>
    "PERMITTED LIENS" means  (a) liens for  taxes, assessments and  governmental
charges  not then due or the validity of  which is being contested in good faith
by appropriate proceedings,  promptly instituted and  diligently conducted,  and
for  which adequate  reserves have  been established  to the  extent required by
GAAP; (b)  mechanics', workmen's,  materialman's,  operator's or  similar  liens
arising  in  the ordinary  course  of business;  (c)  easements, rights  of way,
restrictions and other similar encumbrances  incurred in the ordinary course  of
business  or  minor imperfections  in  title that  do  not impair  the  value of
property for its intended use; (d) liens on, or related to, properties to secure
all or  part  of the  costs  incurred in  the  ordinary course  of  business  of
exploration,  drilling,  development  or  operation  thereof;  (e)  judgment and
attachment liens not giving rise to an  Event of Default or liens created by  or
existing  from  any  litigation or  legal  proceeding that  are  currently being
contested in  good faith  by appropriate  proceedings, promptly  instituted  and
diligently  conducted, and  for which  adequate reserves  have been  made to the
extent required by GAAP; (f)  liens on deposits made  in the ordinary course  of
business;  (g) liens  in favor of  collecting or  payor banks having  a right of
selloff, revocation, refund or chargeback  with respect to money or  instruments
of  the Company or any Subsidiary on deposit with or in possession of such bank;
(h) liens on  pipeline or pipeline  facilities which arise  out of operation  of
law;  (i) liens on deposits to secure public or statutory obligations or in lieu
of surety or appeal bonds entered into  in the ordinary course of business;  (j)
liens  reserved  in oil  and gas  leases for  bonus or  rental payments  and for
compliance  with  the  terms  of  such  leases;  and  (k)  liens  arising  under
partnership agreements, oil and gas leases, farmout agreements, division orders,
contracts for the sale, purchase, exchange, transportation or processing of oil,
gas  or other hydrocarbons, unitization and pooling declarations and agreements,
development agreements, operating agreements, area of mutual interest agreements
and other agreements that are customary in the Oil and Gas Business.
 
   
    "PERMITTED REFINANCING INDEBTEDNESS" means  any Indebtedness of the  Company
or  any of its Subsidiaries issued in exchange for, or the net proceeds of which
are  used  to  extend,  refinance,  renew,  replace,  defease  or  refund  other
Indebtedness  of the Company or any of  its Subsidiaries; PROVIDED that: (i) the
principal amount of such Permitted Refinancing Indebtedness does not exceed  the
principal  or  accrued  amount  of  the  Indebtedness  so  extended, refinanced,
renewed,  replaced,  defeased  or  refunded;  (ii)  such  Permitted  Refinancing
Indebtedness  has a Weighted Average Life to  Maturity and a final maturity date
equal to  or  greater than  the  Weighted Average  Life  to Maturity  and  final
maturity  date, respectively,  of the  Indebtedness being  extended, refinanced,
renewed, replaced,  defeased  or  refunded;  (iii)  if  the  Indebtedness  being
extended, refinanced, renewed, replaced, defeased or refunded is subordinated in
right  of  payment to  the Notes  or any  Subsidiary Guarantees,  such Permitted
Refinancing Indebtedness has a final maturity date later than the final maturity
date of, and is subordinated in right of payment to the Notes and any Subsidiary
Guarantees on terms at least  as favorable to the Holders  of the Note as  those
contained  in  the  documentation  governing  the  Indebtedness  being extended,
refinanced, renewed, replaced, defeased or refunded; and (iv) such  Indebtedness
is incurred either by the Company or by the Subsidiary who is the obligor on the
Indebtedness   being  extended,  refinanced,   renewed,  replaced,  defeased  or
refunded.
    
 
   
    "PRINCIPAL PROPERTIES" means the oil  and gas properties and other  tangible
assets   and  properties  owned  by  Company   on  the  date  of  the  Indenture
(collectively, the "Original Principal Properties") and assets and properties of
the Company obtained in exchange for any of the Original Principal Properties.
    
 
    "PRODUCTION PAYMENTS"  means,  collectively,  Dollar-Denominated  Production
Payments and Volumetric Production Payments.
 
    "QUALIFIED  STOCK" means, for any Person, any  and all Capital Stock of such
Person, other than Disqualified Stock.
 
    "RESTRICTED  INVESTMENT"  means  an   Investment  other  than  a   Permitted
Investment.
 
    "SENIOR  BANK  INDEBTEDNESS" means  the  Indebtedness outstanding  under the
Credit Facility.
 
    "SENIOR INDEBTEDNESS" means (i)  the Senior Bank  Indebtedness and (ii)  any
other  Indebtedness permitted to be  incurred by the Company  under the terms of
the Indenture, unless the instrument  under which such Indebtedness is  incurred
expressly provides that it is subordinated in right of
 
                                       80
<PAGE>
payment  to any Indebtedness for money borrowed. Notwithstanding anything to the
contrary in  the  foregoing,  Senior  Indebtedness  will  not  include  (w)  any
liability for federal, state, local or other taxes owed or owing by the Company,
(x)  any Indebtedness  of the Company  to any of  its Subsidiaries, Unrestricted
Subsidiaries  or  other  Affiliates,  (y)   any  trade  payables,  or  (z)   any
Indebtedness that is incurred in violation of the Indenture.
 
    "SENIOR  REVOLVING  INDEBTEDNESS"  means  revolving  credit  borrowings  and
letters of credit  under the Credit  Facility and/or any  successor facility  or
facilities.
 
    "SUBSIDIARY"  means,  with  respect  to  any  Person,  (i)  any corporation,
association or other business entity of which more than 50% of the total  voting
power  of shares of Capital Stock entitled  (without regard to the occurrence of
any contingency) to  vote in  the election  of directors,  managers or  trustees
thereof  is at  the time  owned or controlled,  directly or  indirectly, by such
Person or one or more of the other Subsidiaries of that Person (or a combination
thereof) and (ii) any partnership (a)  the sole general partner or the  managing
general  partner of which is  such Person or a Subsidiary  of such Person or (b)
the only  general  partners  of  which  are  such  Person  or  of  one  or  more
Subsidiaries  of such Person  (or any combination  thereof). Notwithstanding the
foregoing, an Unrestricted Subsidiary shall not  be a Subsidiary of the  Company
for any purposes of the Indenture.
 
    "UNRESTRICTED  SUBSIDIARY" means any Subsidiary,  if designated by the Board
of Directors of the  Company as an Unrestricted  Subsidiary pursuant to a  Board
Resolution  and  permitted to  be so  designated  pursuant to  the terms  of the
Indenture.
 
    "VOLUMETRIC  PRODUCTION  PAYMENTS"   means  volumetric  production   payment
obligations  of the  Company or any  of its  Subsidiaries that are  or, upon the
occurrence of  a contingent  event, would  be recorded  as deferred  revenue  in
accordance  with GAAP,  together with  all undertakings  and obligations  of the
Company or any of its Subsidiaries in connection therewith, which will be deemed
to constitute debt for borrowed money for purpose of the Indenture.
 
    "VOTING STOCK" of a corporation means  all classes of Capital Stock of  such
corporation  then outstanding and  normally entitled to vote  in the election of
directors.
 
    "WEIGHTED AVERAGE LIFE TO MATURITY" means, when applied to any  Indebtedness
at any date, the number of years obtained by dividing (i) the sum of the product
obtained  by  multiplying (a)  the amount  of  each then  remaining installment,
sinking fund, serial maturity or other required payments of principal, including
payments at  final maturity,  in respect  thereof, by  (b) the  number of  years
(calculated  to the nearest one-twelfth) that  will elapse between such date and
the making of  such payment, by  (ii) the then  outstanding principal amount  of
such Indebtedness.
 
    "WHOLLY  OWNED SUBSIDIARY" of  any Person means a  Subsidiary of such Person
(i) all of the outstanding Capital  Stock or other ownership interests of  which
(other  than directors  qualifying shares)  shall at the  time be  owned by such
Person or  by one  or more  Wholly Owned  Subsidiaries of  such Person  or  (ii)
organized  in a foreign jurisdiction and is  required by the applicable laws and
regulations of such foreign jurisdiction to be partially owned by the government
of such foreign jurisdiction or individual or corporate citizens of such foreign
jurisdiction in order for such Subsidiary  to transact business in such  foreign
jurisdiction, provided that such Person or one or more Wholly Owned Subsidiaries
of  such Person, owns the remaining Capital  Stock or ownership interest in such
Subsidiary and, by contract or  otherwise, controls the management and  business
of  such  Subsidiary and  derives  the economic  benefits  of ownership  of such
Subsidiary to substantially the same extent as if such Subsidiary were a  wholly
owned  Subsidiary.  Unrestricted  Subsidiaries  shall  not  be  included  in the
definition of Wholly Owned Subsidiary for any purposes of the Indenture.
 
                                       81
<PAGE>
                       DESCRIPTION OF OTHER INDEBTEDNESS
 
EXISTING DEBT FACILITY
 
    In  June 1996,  the Company entered  into a credit  agreement (the "Existing
Debt Facility")  provided by  NationsBridge, L.L.C.  and NationsBank,  N.A.  and
consisting  of a $95.0  million revolving credit  loan (the "Existing Revolver")
and a $30.0  million term  loan (the "Existing  Term Loan").  The Existing  Debt
Facility  provided funds to consummate the 1996 Acquisition and to refinance the
Company's prior senior bank facility.  Prudential Securities Group Inc.  ("PGI")
has purchased an interest in the Existing Debt Facility.
 
    The Existing Revolver and the Existing Term Loan each matures June 10, 1999.
No  periodic principal reductions are required with respect to the Existing Term
Loan; however, quarterly principal reductions in the amount of $3.0 million  are
required  with respect to the Existing  Revolver, commencing January 1, 1997. In
addition, the Existing  Debt Facility requires  that the net  proceeds from  the
Notes  Offering be applied to reduce  the amounts outstanding under the Existing
Revolver and the  Existing Term  Loan, and  100% of  the net  proceeds from  the
Common  Stock  Offering  are  required  to be  utilized  to  reduce  the amounts
outstanding under the Existing Term Loan and Existing Revolver.
 
   
    Interest accrues on  the Existing Term  Loan initially at  14.0% per  annum,
increasing  by 0.5% per annum  at the end of  each successive three month period
(commencing September 13, 1996) up to a maximum of 16.5% per annum. Interest may
be paid in cash  or "in kind"  by delivery of additional  notes having the  same
terms as the notes issued pursuant to the Existing Term Loan. Interest under the
Existing  Revolver accrues, at the option of  the Company, at a margin in excess
of either NationsBank, N.A. "LIBOR" rate, up to a maximum of 5.0% per annum,  or
NationsBank, N.A. fluctuating "prime rate" up to a maximum of 2.75% per annum.
    
 
    The  Existing Debt Facility is  secured by a pledge  of substantially all of
the Company's  assets,  guaranties by  the  Company's subsidiaries  and  limited
guaranties  by  Messrs. Liedtke,  Grella  and Musselman  proportionate  to their
membership interests in the LLC.
 
CREDIT FACILITY
 
   
    The Credit Facility will provide the Company with a revolving facility based
on the borrowing base of its oil and  gas assets which will initially be set  at
$50.0 million, none of which is expected to be outstanding at its inception. The
Credit  Facility is expected to  be secured by a  pledge of substantially all of
the Company's  assets. See  "Mangement's Discussion  and Analysis  of  Financial
Condition  and Results of  Operations -- Liquidity and  Capital Resources" for a
further description of the Credit Facility.
    
 
                          DESCRIPTION OF CAPITAL STOCK
 
    The authorized capital stock of the Company consists of 20,000,000 shares of
Common Stock, par value $0.10 per share ("Common Stock") and 3,000,000 shares of
preferred stock,  par  value  $0.10  per share  ("Preferred  Stock").  Upon  the
completion  of the  Offerings and the  Corporate Reorganization,  the issued and
outstanding capital stock of  the Company will consist  of 10,000,000 shares  of
Common Stock (or 10,600,000 shares if the underwriters' over-allotment option is
exercised in full).
 
    The  following description of certain matters  relating to the capital stock
of the Company  is summary in  nature and is  qualified in its  entirety by  the
provisions  of the Company's Certificate of  Incorporation and Bylaws, copies of
which have been filed  as exhibits to the  Registration Statement of which  this
Prospectus is a part.
 
COMMON STOCK
 
    The  holders  of Common  Stock are  entitled to  one vote  per share  on all
matters submitted to a  vote of stockholders of  the Company. In addition,  such
holders  are  entitled to  receive ratably  such  dividends, if  any, as  may be
declared from  time to  time by  the Board  of Directors  out of  funds  legally
 
                                       82
<PAGE>
available  therefor,  subject  to  the payment  of  preferential  dividends with
respect to any Preferred Stock that from time to time may be outstanding. In the
event of the dissolution, liquidation or winding-up of the Company, the  holders
of  Common Stock  are entitled  to share ratably  in all  assets remaining after
payment of all liabilities of the Company and subject to the prior  distribution
rights  of the holders  of any Preferred  Stock that may  be outstanding at that
time. The  holders of  Common Stock  do  not have  cumulative voting  rights  or
preemptive  rights. All shares of Common Stock outstanding and to be outstanding
after the Common Stock Offering will be fully paid and nonassessable.
 
PREFERRED STOCK
 
    The Board  of Directors  has  the authority  to  issue 3,000,000  shares  of
Preferred  Stock, in  one or  more series, and  to fix  the rights, preferences,
qualifications, privileges,  limitations or  restrictions  of each  such  series
without  any further vote or action  by the stockholders, including the dividend
rights, dividend rate,  conversion rights,  voting rights,  terms of  redemption
(including  sinking fund  provisions), redemption  price or  prices, liquidation
preferences and the number of shares constituting any series or the designations
of such series.  No shares of  Preferred Stock  have ever been  issued, and  the
Company  has no present plans to issue any Preferred Stock. In certain instances
the Indenture limits the  ability of the Company  to issue Preferred Stock.  See
"Description  of Notes  -- Certain Covenants  -- Incurrence  of Indebtedness and
Issuance of Preferred Stock."
 
                                       83
<PAGE>
                                  UNDERWRITING
 
   
    Upon the terms and subject to  the conditions of the Underwriting  Agreement
(the  "Underwriting Agreement") among the  Company, NationsBanc Capital Markets,
Inc.  and   Prudential  Securities   Incorporated  (the   "Underwriters"),   the
Underwriters  severally have agreed to purchase from the Company and the Company
has agreed to sell to the  Underwriters severally the principal amount of  Notes
set forth opposite the names of such Underwriters below:
    
 
<TABLE>
<CAPTION>
                                                                                                     PRINCIPAL
UNDERWRITER                                                                                            AMOUNT
- ------------------------------------------------------------------------------------------------  ----------------
<S>                                                                                               <C>
NationsBanc Capital Markets, Inc................................................................  $
Prudential Securities Incorporated..............................................................
                                                                                                  ----------------
    Total.......................................................................................  $    100,000,000
                                                                                                  ----------------
                                                                                                  ----------------
</TABLE>
 
    In the Underwriting Agreement, the several Underwriters have agreed, subject
to  certain conditions, to purchase all of  the Notes, if any are purchased. The
Underwriting  Agreement  provides  that,  in  the  event  of  a  default  by  an
Underwriter,   in   certain   circumstances,   the   purchase   commitments   of
non-defaulting Underwriters may be increased  or the Underwriting Agreement  may
be terminated.
 
    The  Company has been advised by the Underwriters that they propose to offer
the Notes to the public  initially at the price set  forth on the cover page  of
this Prospectus, to certain securities dealers (who may include Underwriters) at
such  price less a concession not in  excess of    %  of the amount per Note and
that the Underwriters and such dealers may  reallow a discount not in excess  of
   %  of the amount per Note to other dealers, including the Underwriters. After
the closing of the  public offering, the public  offering price, the  concession
and the discount to other dealers may be changed by the Underwriters.
 
    There  is no currently  existing trading market for  the Notes, and although
the Underwriters have advised the Company  that they currently intend to make  a
market  in the Notes, they are not obligated to do so and any such market making
may be discontinued at any time, without  notice, in the sole discretion of  the
Underwriters.  Accordingly, there can  be no assurance as  to the development or
liquidity of any market that may develop for the Notes.
 
   
    The Company  has  agreed  to  indemnify  the  Underwriters  against  certain
liabilities,  including liabilities under the Securities Act of 1933, as amended
(the "Securities Act"),  or to contribute  to payments the  Underwriters may  be
required to make in respect thereof.
    
 
   
    The  Underwriters  have informed  the  Company that  they  do not  expect to
confirm sales of Notes offered hereby  to any accounts over which they  exercise
discretionary authority.
    
 
   
    NationsBanc Capital Markets, Inc. is an affiliate of NationsBank, N.A., NBCC
and  NationsBridge,  L.L.C.  NationsBridge,  L.L.C.  and  NationsBank,  N.A. are
lenders under  the Existing  Credit Facility.  PGI, an  affiliate of  Prudential
Securities  Incorporated, is also  a lender under  the Existing Credit Facility.
See "Description  of Other  Indebtedness." NationsBridge,  L.L.C.,  NationsBank,
N.A. and PGI will receive their respective proportionate shares of the repayment
by  the Company  of borrowings  under the  Existing Debt  Facility from  the net
proceeds of the Offerings. Prudential Securities Incorporated is also acting  as
an  underwriter in the  Company's concurrent Common Stock  Offering for which it
will receive customary underwriting discounts and commissions. In addition,  the
Underwriters  and their respective affiliates  provide or have provided banking,
advisory and other financial services for the Company in the ordinary course  of
business for which they have received customary compensation.
    
 
   
    NBCC  is a stockholder  of the Company and  will receive approximately $16.3
million of the  proceeds of  the Offerings  in redemption  of a  portion of  the
membership  interests owned by it  and in a distribution  to it in the Corporate
Reorganization. See "Use of Proceeds," "The Company -- Corporate Reorganization"
and "Security  Ownership of  Certain  Beneficial Owners  and Management."  As  a
result  of such ownership, The National  Association of Securities Dealers, Inc.
("NASD") may view
    
 
                                       84
<PAGE>
this offering as  a participation by  NationsBanc Capital Markets,  Inc. in  the
distribution  in a public  offering of the  securities of an  affiliate and this
Notes Offering is  being made pursuant  to the  provisions of Rule  2720 of  the
NASD's  Conduct  Rules.  In  accordance with  Rule  2720,  Prudential Securities
Incorporated is  acting as  a  qualified independent  underwriter in  the  Notes
Offering  and is assuming the responsibilities of  acting as such in pricing the
Notes Offering and conducting due diligence.
 
                                 LEGAL MATTERS
 
    Certain legal matters related to the  Notes offered hereby are being  passed
upon  for  the  Company  by  Cotton, Bledsoe,  Tighe  &  Dawson,  a Professional
Corporation, Midland,  Texas.  Certain  matters  will be  passed  upon  for  the
Underwriters by Baker & Botts, L.L.P., Houston, Texas.
 
                                    EXPERTS
 
    The  consolidated  financial  statements  of  Costilla  Energy,  L.L.C.  and
subsidiaries as of December 31, 1995 and for the year then ended, the statements
of revenues and direct operating expenses of the 1996 Acquisition for the  years
ended  December 31,  1993, 1994  and 1995,  and the  statements of  revenues and
direct operating expenses of the 1995  Acquisition for the years ended  December
31, 1993 and 1994, and the period ended June 12, 1995, have been included herein
and  in the  registration statement  in reliance  upon the  report of  KPMG Peat
Marwick LLP,  independent  certified  public  accountants,  appearing  elsewhere
herein,  and  upon the  authority  of said  firm  as experts  in  accounting and
auditing.
 
    The  consolidated  financial  statements  of  Costilla  Energy,  L.L.C.  and
subsidiaries  as of December 31, 1994, and for the years ended December 31, 1993
and 1994,  have  been included  herein  and  in the  registration  statement  in
reliance  upon  the report  of Elms,  Faris &  Co., P.C.,  independent certified
public accountants, appearing elsewhere herein,  and upon the authority of  said
firm as experts in accounting and auditing.
 
   
    In  September 1995, the Company changed its principal accountants from Elms,
Faris & Co., P.C. to  KPMG Peat Marwick LLP. The  reports of Elms, Faris &  Co.,
P.C.  on the Company's financial statements for the year ended December 31, 1994
did not  contain an  adverse opinion  or a  disclaimer of  opinion, nor  was  it
qualified  or modified in any  way as to uncertainty,  audit scope or accounting
principles. Moreover, there were no disagreements  with Elms, Faris & Co.,  P.C.
on  any  matter  of  accounting  principles  or  practices,  financial statement
disclosure, or auditing  scope or  procedure. The members  of the  LLC made  the
decision to change the LLC's principal accountants.
    
 
    Certain   information  appearing  in  this  Prospectus  regarding  estimated
quantities of oil and  gas reserves and the  discounted present value of  future
pre-tax cash flows therefrom attributable to the Company's properties and to the
properties  included in  the 1996  Acquisition is  based upon  estimates of such
reserves and present values prepared  by Williamson Petroleum Consultants,  Inc.
All  of  such information  has  been so  included  herein in  reliance  upon the
authority of such firm as  experts in such matters. Set  forth as Appendix A  is
Williamson's  Summary Reserve Report dated July 23, 1996 with respect to the oil
and gas interests of the Company and with respect to properties acquired in  the
1996 Acquisition.
 
                             AVAILABLE INFORMATION
 
    Upon  completion  of  the Offerings,  the  Company  will be  subject  to the
informational requirements of the  Securities Exchange Act  of 1934, as  amended
(the  "Exchange Act"),  and, in accordance  therewith, will  file reports, proxy
statements and other  information with  the Securities  and Exchange  Commission
(the  "Commission"). Such reports, proxy  statements and other information filed
by the Company  with the  Commission can be  inspected at  the Public  Reference
Section of the Commission at Room 1024, Judiciary Plaza, 450 Fifth Street, N.W.,
Washington,  D.C. 20549, and the Regional  Offices of the Commission at Citicorp
Center,   500   West   Madison    Street,   Suite   1400,   Chicago,    Illinois
 
                                       85
<PAGE>
60661-2511,  and 7 World Trade Center, New  York, New York 10048. Copies of such
material can  also  be  obtained  from  the  Public  Reference  Section  of  the
Commission  at Room 1024,  Judiciary Plaza, 450  Fifth Street, N.W., Washington,
D.C. 20549, at prescribed rates. The Commission maintains a World Wide Web  site
on   the  Internet  at  HTTP:\\WWW.SEC.GOV  that  contains  reports,  proxy  and
information statements  and other  information regarding  registrants that  file
electronically with the Commission.
 
    The  Company has filed with the  Commission a Registration Statement on Form
S-1 under the  Securities Act  with respect to  the Notes  offered hereby.  This
Prospectus,  which constitutes  a part of  the Registration  Statement, does not
contain all of the information set forth in the Registration Statement,  certain
items  of  which are  contained  in exhibits  to  the Registration  Statement as
permitted  by  the  rules  and  regulations  of  the  Commission.  For   further
information  with respect to the Company and the Notes offered hereby, reference
is made to the Registration Statement, including the exhibits thereto, which may
be inspected without charge at the public reference facilities maintained by the
Commission at 450 Fifth Street, N.W., Washington, D.C. 20549 and at the Regional
Offices of  the  Commission,  and copies  of  which  may be  obtained  from  the
Commission  at prescribed rates.  Statements made in  this Prospectus concerning
the contents of any  document referred to herein  are not necessarily  complete.
With  respect to each such  document filed with the  Commission as an exhibit to
the Registration Statement, reference is made to the exhibit for a more complete
description of the matter involved, and each such statement made herein shall be
deemed qualified by such reference.
 
                                       86
<PAGE>
                                    GLOSSARY
 
    The terms defined in this section are used throughout this Prospectus.
 
   
    ADJUSTED EBITDA.  Calculated by adding interest, income taxes, depreciation,
depletion and amortization, exploration and abandonment costs and  extraordinary
loss resulting from extinguishment of debt to net income (loss).
    
 
    ALL-IN  FINDING COSTS.  The amount  of total capital expenditures, including
acquisition costs,  and  exploration  and  abandonment costs  for  oil  and  gas
activities  divided by  the amount of  proved reserves (expressed  in BOE) added
during the specified period (including the effect on proved reserves of  reserve
revisions).
 
    BBL.   One stock tank barrel, or  42 U.S. gallons liquid volume, used herein
in reference to crude oil or other liquid hydrocarbons.
 
    BCF.  One billion cubic feet.
 
    BOE.  Equivalent barrels  of oil. In reference  to natural gas, natural  gas
equivalents  are determined using the ratio of six Mcf of natural gas to one Bbl
of crude oil, condensate or natural gas liquids.
 
    BTU.  One British thermal unit. The  quantity of heat required to raise  the
temperature of one pound of water one degree Fahrenheit.
 
    DEVELOPED ACREAGE.  The number of acres which are allocated or assignable to
producing wells or wells capable of production.
 
    DEVELOPMENT  WELL.  A well  drilled within the proved area  of an oil or gas
reservoir to the depth of a stratigraphic horizon known to be productive.
 
   
    DRY WELL.  A well  found to be incapable of  producing either oil or gas  in
sufficient quantifies to justify completion of an oil or gas well.
    
 
    EXPLORATORY  WELL.   A well  drilled to find  and produce  oil or  gas in an
unproved area,  to find  a  new reservoir  in a  field  previously found  to  be
productive of oil or gas in another reservoir, or to extend a known reservoir.
 
    GROSS  ACRES OR GROSS WELLS.  The total  acres or wells, as the case may be,
in which a working interest is owned.
 
    MBBL.  One thousand barrels of crude oil or other liquid hydrocarbons.
 
    MBOE.  One thousand barrels of oil equivalent.
 
    MMBOE.  One million barrels of oil equivalent.
 
    MMBBLS.  One million barrels of crude oil or other liquid hydrocarbons.
 
    MMBTU.  One million Btu's.
 
    MCF.  One thousand cubic feet.
 
    MMCF.  One million cubic feet.
 
    NET ACRES OR NET WELLS.  The  sum of the fractional working interests  owned
in gross acres or gross wells.
 
    PRESENT  VALUE OF ESTIMATED FUTURE NET REVENUES OR PV-10 VALUE.  The present
value of estimated  future net revenues  is an estimate  of future net  revenues
from  a property at its  acquisition date, at a  specified date, after deducting
production and ad valorem  taxes, future capital  costs and operating  expenses,
but  before deducting  federal income taxes.  The future net  revenues have been
discounted at an  annual rate  of 10% to  determine their  "present value."  The
present value is shown to indicate the
 
                                       87
<PAGE>
effect  of time on the  value of the revenue stream  and should not construed as
being the fair market  value of the properties.  Estimates have been made  using
constant oil and natural gas prices and operating costs at the specified date.
 
    PRODUCTIVE  WELL.  A  well that is producing  oil or gas  that is capable of
production.
 
    PROVED DEVELOPED RESERVES.   Reserves that can be  expected to be  recovered
through existing wells with existing equipment and operating methods.
 
    PROVED  RESERVES.   The estimated quantities  of crude oil,  natural gas and
natural gas  liquids  which geological  and  engineering data  demonstrate  with
reasonable  certainty to  be recoverable in  future years  from known reservoirs
under existing economic and operating conditions.
 
    PROVED UNDEVELOPED RESERVES.   Reserves  that are expected  to be  recovered
from  new wells on undrilled acreage, or  from existing wells where a relatively
major expenditure is required for recompletion.
 
    ROYALTY INTEREST.   An interest  in an oil  and gas  property entitling  the
owner to a share of oil and gas production free of costs of production.
 
    3-D  SEISMIC.   Advanced  technology  method of  detecting  accumulations of
hydrocarbons identified by the collection  and measurement of the intensity  and
timing  of sound waves  transmitted into the  earth as they  reflect back to the
surface.
 
    UNDEVELOPED ACREAGE.  Lease acreage on which wells have not been drilled  or
completed  to a point that would  permit the production of commercial quantities
of oil and gas regardless of whether such acreage contains proved reserves.
 
    WORKING INTEREST.  The operating interest which gives the owner the right to
drill, produce and conduct operating activities  on the property and a share  of
production.
 
                                       88
<PAGE>
                         INDEX TO FINANCIAL STATEMENTS
 
   
<TABLE>
<S>                                                                                    <C>
Financial Statements of Costilla Energy, L.L.C.:
  Independent Auditors' Reports......................................................        F-2
  Consolidated Balance Sheets as of December 31, 1994 and 1995, and June 30, 1996
   (unaudited).......................................................................        F-4
  Consolidated Statements of Operations for the years ended December 31, 1993, 1994,
   and 1995, and the six months ended June 30, 1995 and 1996 (unaudited).............        F-5
  Consolidated Statements of Members' Capital for the years ended December 31, 1993,
   1994, and 1995, and the six months ended June 30, 1995 (unaudited)................        F-6
  Consolidated Statements of Cash Flows for the years ended December 31, 1993, 1994,
   and 1995, and the six months ended June 30, 1995 and 1996 (unaudited).............        F-7
  Notes to Consolidated Financial Statements.........................................        F-8
 
Financial Statements of the 1995 Acquisition:
  Independent Auditors' Report.......................................................       F-22
  Statements of Revenues and Direct Operating Expenses for the years ended December
   31, 1993 and 1994 and the period ended June 12, 1995..............................       F-23
  Notes to the Statements of Revenues and Direct Operating Expenses..................       F-24
 
Financial Statements of the 1996 Acquisition:
  Independent Auditors' Report.......................................................       F-27
  Statements of Revenues and Direct Operating Expenses for the years ended December
   31, 1993, 1994 and 1995, and the periods ended June 14, 1995 and 1996
   (unaudited).......................................................................       F-28
  Notes to the Statements of Revenues and Direct Operating Expenses..................       F-29
</TABLE>
    
 
                                      F-1
<PAGE>
                          INDEPENDENT AUDITORS' REPORT
 
The Members
Costilla Energy, L.L.C. (a Texas limited liability company):
 
    We  have  audited the  accompanying consolidated  balance sheet  of Costilla
Energy, L.L.C.  (a  Texas limited  liability  company) and  subsidiaries  as  of
December  31,  1995,  and  the  related  consolidated  statement  of operations,
members' capital, and  cash flows for  the year then  ended. These  consolidated
financial  statements are  the responsibility  of the  Company's management. Our
responsibility is to express an opinion  on these financial statements based  on
our audit.
 
    We  conducted  our  audit  in accordance  with  generally  accepted auditing
standards. Those standards require that we plan and perform the audit to  obtain
reasonable assurance about whether the financial statements are free of material
misstatement.  An audit includes examining, on a test basis, evidence supporting
the amounts and disclosures in the financial statements. An audit also  includes
assessing  the  accounting principles  used  and significant  estimates  made by
management, as well as evaluating the overall financial statement  presentation.
We believe that our audit provides a reasonable basis for our opinion.
 
    In  our  opinion, the  consolidated financial  statements referred  to above
present fairly, in  all material  respects, the financial  position of  Costilla
Energy,  L.L.C. and  subsidiaries as  of December 31,  1995, and  the results of
their operations and  their cash flows  for the year  then ended, in  conformity
with generally accepted accounting principles.
 
                                                           KPMG PEAT MARWICK LLP
 
Midland, Texas
   
April 16, 1996 (except  with respect to matters  discussed in the last paragraph
               of Note 7 and Note 12, as to which the date is June 14, 1996.)
    
 
                                      F-2
<PAGE>
                          INDEPENDENT AUDITORS' REPORT
 
The Members
Costilla Energy, L.L.C.:
 
    We have  audited the  accompanying consolidated  balance sheet  of  Costilla
Energy,  L.L.C.  (a  Texas  limited  liability  company)  and  subsidiaries (the
combination of  CSL  Partners,  Costilla  Petroleum  Corporation  and  Statewide
Minerals, L.C.) as of December 31, 1994, and the related consolidated statements
of operations, members' capital, and cash flows for the years ended December 31,
1993 and 1994. These consolidated financial statements are the responsibility of
the  Company's management. Our responsibility is  to express an opinion on these
financial statements based on our audits.
 
    We conducted  our  audits in  accordance  with generally  accepted  auditing
standards. Those standards require that we plan and perform the audits to obtain
reasonable assurance about whether the financial statements are free of material
misstatement.  An audit includes examining, on a test basis, evidence supporting
the amounts and disclosures in the financial statements. An audit also  includes
assessing  the  accounting principles  used  and significant  estimates  made by
management, as well as evaluating the overall financial statement  presentation.
We believe that our audits provides a reasonable basis for our opinion.
 
    In  our  opinion, the  consolidated financial  statements referred  to above
present fairly, in all material respects, the consolidated financial position of
Costilla Energy,  L.L.C. and  subsidiaries  as of  December  31, 1994,  and  the
results  of their operations and  their cash flows for  the years ended December
31, 1993 and 1994, in conformity with generally accepted accounting principles.
 
                                          ELMS, FARIS & CO., P.C.
 
Midland, Texas
March 31, 1995
 
                                      F-3
<PAGE>
                            COSTILLA ENERGY, L.L.C.
                      (A TEXAS LIMITED LIABILITY COMPANY)
                          CONSOLIDATED BALANCE SHEETS
                                 (IN THOUSANDS)
 
                                     ASSETS
   
<TABLE>
<CAPTION>
                                                                                              DECEMBER 31,
                                                                                            ----------------   JUNE 30,
                                                                                             1994     1995       1996
                                                                                            -------  -------  -----------
                                                                                                              (UNAUDITED)
<S>                                                                                         <C>      <C>      <C>
Current assets:
  Cash and cash equivalents...............................................................  $   137  $ 2,866    $ 1,164
  Accounts receivable:
    Trade, net............................................................................    1,042    3,154      2,521
    Affiliates............................................................................       --      507        927
    Oil and gas sales.....................................................................    1,715    3,915      5,337
  Prepaid and other current assets........................................................      223      439      2,629
                                                                                            -------  -------  -----------
        Total current assets..............................................................    3,117   10,881     12,578
                                                                                            -------  -------  -----------
Property, plant and equipment, at cost:
  Oil and gas properties, using the successful efforts method of accounting:
    Proved properties.....................................................................   22,794   79,897    126,809
    Unproved properties...................................................................    2,060    2,903      4,615
  Accumulated depletion, depreciation and amortization....................................   (3,562)  (9,413)   (13,933)
                                                                                            -------  -------  -----------
                                                                                             21,292   73,387    117,491
                                                                                            -------  -------  -----------
Other property and equipment, net.........................................................       76      679      1,640
Deferred charges (Note 2).................................................................       29    1,736      2,654
Note receivable -- affiliate..............................................................      390      684        684
                                                                                            -------  -------  -----------
                                                                                            $24,904  $87,367    $135,047
                                                                                            -------  -------  -----------
                                                                                            -------  -------  -----------
 
<CAPTION>
 
                              LIABILITIES, REDEEMABLE MEMBERS' CAPITAL AND MEMBERS' CAPITAL
<S>                                                                                         <C>      <C>      <C>
Current liabilities:
  Current maturities of long-term debt....................................................  $    22  $    --    $    98
  Trade accounts payable..................................................................    1,712    5,467      4,587
  Undistributed revenue...................................................................      110    1,227      1,524
  Other current liabilities...............................................................      192    1,691      2,103
                                                                                            -------  -------  -----------
        Total current liabilities.........................................................    2,036    8,385      8,312
                                                                                            -------  -------  -----------
Long-term debt, less current maturities (Note 7)..........................................   23,591   71,494    122,267
Deferred income (Note 2)..................................................................       24    3,319      2,623
Other noncurrent liabilities..............................................................       --       38         --
                                                                                            -------  -------  -----------
        Total liabilities.................................................................   25,651   83,236    133,202
                                                                                            -------  -------  -----------
Redeemable members' capital (Note 10).....................................................       --   12,278     13,557
                                                                                            -------  -------  -----------
Members' capital (Note 10)................................................................     (747)  (8,147)   (11,712)
Commitments and contingencies (Note 8)....................................................       --       --         --
                                                                                            -------  -------  -----------
                                                                                            $24,904  $87,367    $135,047
                                                                                            -------  -------  -----------
                                                                                            -------  -------  -----------
</TABLE>
    
 
          See accompanying notes to consolidated financial statements.
 
                                      F-4
<PAGE>
                            COSTILLA ENERGY, L.L.C.
                      (A TEXAS LIMITED LIABILITY COMPANY)
                     CONSOLIDATED STATEMENTS OF OPERATIONS
                                 (IN THOUSANDS)
 
   
<TABLE>
<CAPTION>
                                                                                                SIX MONTHS ENDED
                                                                YEARS ENDED DECEMBER 31,            JUNE 30,
                                                             -------------------------------  --------------------
                                                               1993       1994       1995       1995       1996
                                                             ---------  ---------  ---------  ---------  ---------
                                                                                                  (UNAUDITED)
<S>                                                          <C>        <C>        <C>        <C>        <C>
Revenues:
  Oil and gas sales........................................  $   4,231  $   7,637  $  21,693  $   5,568  $  19,445
  Interest and other.......................................         56         87        123          5         40
  Gain on sale of assets...................................        110        112         --         --         40
                                                             ---------  ---------  ---------  ---------  ---------
                                                                 4,397      7,836     21,816      5,573     19,525
                                                             ---------  ---------  ---------  ---------  ---------
Expenses:
  Oil and gas production...................................      1,688      2,349     10,024      2,268      8,093
  Oil and gas production -- affiliates.....................         --          2        331        145        185
  General and administrative...............................        639        634      2,910        678      2,439
  General and administrative -- affiliates.................        313        550        661        330        370
  Exploration and abandonments.............................        218        793      1,650      1,007        308
  Depreciation, depletion and amortization.................        884      1,847      5,958      1,367      4,620
  Interest.................................................        605      1,458      4,591      1,046      4,156
  Other....................................................         --         --          2         --         --
                                                             ---------  ---------  ---------  ---------  ---------
                                                                 4,347      7,633     26,127      6,841     20,171
                                                             ---------  ---------  ---------  ---------  ---------
    Income (loss) before federal income taxes and
     extraordinary item....................................  $      50  $     203  $  (4,311) $  (1,268)      (646)
Provision for federal income taxes
  Current..................................................        (25)         8          3         --         --
  Deferred.................................................          2         32         --         --         --
                                                             ---------  ---------  ---------  ---------  ---------
    Income (loss) before extraordinary item................  $      73  $     163  $  (4,314) $  (1,268) $    (646)
    Extraordinary loss resulting from extinguishment of
     debt (Note 7).........................................         --         --         --         --     (1,640)
                                                             ---------  ---------  ---------  ---------  ---------
    Net income (loss)......................................  $      73  $     163  $  (4,314) $  (1,268) $  (2,286)
                                                             ---------  ---------  ---------  ---------  ---------
                                                             ---------  ---------  ---------  ---------  ---------
</TABLE>
    
 
          See accompanying notes to consolidated financial statements.
 
                                      F-5
<PAGE>
                            COSTILLA ENERGY, L.L.C.
                      (A TEXAS LIMITED LIABILITY COMPANY)
                  CONSOLIDATED STATEMENTS OF MEMBERS' CAPITAL
                                 (IN THOUSANDS)
 
   
<TABLE>
<CAPTION>
                                                                                                         MEMBERS'
                                                                                                         CAPITAL
                                                                                                        ----------
<S>                                                                                                     <C>
Balance at January 1, 1993............................................................................  $      433
  Net income..........................................................................................          73
  Contributions.......................................................................................           1
  Withdrawals.........................................................................................        (456)
                                                                                                        ----------
Balance at December 31, 1993..........................................................................          51
  Net income..........................................................................................         163
  Withdrawals.........................................................................................        (961)
                                                                                                        ----------
Balance at December 31, 1994..........................................................................        (747)
  Issuance costs (Note 10)............................................................................        (753)
  Net loss............................................................................................      (4,314)
  Withdrawals.........................................................................................         (55)
  Preferred return and accretion of redeemable members' capital.......................................      (2,278)
                                                                                                        ----------
Balance at December 31, 1995..........................................................................      (8,147)
  Net loss (unaudited)................................................................................      (2,286)
  Preferred return and accretion of redeemable members' capital (unaudited)...........................      (1,279)
                                                                                                        ----------
Balance at June 30, 1996 (unaudited)..................................................................  $  (11,712)
                                                                                                        ----------
                                                                                                        ----------
</TABLE>
    
 
          See accompanying notes to consolidated financial statements.
 
                                      F-6
<PAGE>
                            COSTILLA ENERGY, L.L.C.
                      (A TEXAS LIMITED LIABILITY COMPANY)
                     CONSOLIDATED STATEMENTS OF CASH FLOWS
                                 (IN THOUSANDS)
 
   
<TABLE>
<CAPTION>
                                                                                                                SIX MONTHS ENDED
                                                                                   YEARS ENDED DECEMBER 31,         JUNE 30,
                                                                                  ---------------------------  ------------------
                                                                                   1993      1994      1995      1995      1996
                                                                                  -------  --------  --------  --------  --------
                                                                                                                  (UNAUDITED)
<S>                                                                               <C>      <C>       <C>       <C>       <C>
Cash flows from operating activities:
  Net income (loss).............................................................  $    73  $    163  $ (4,314) $ (1,268) $ (2,286)
  Adjustments to reconcile net income (loss) to net cash provided by operating
   activities:
    Depreciation, depletion and amortization....................................      884     1,847     5,958     1,367     4,620
    Amortization of deferred charges............................................       --        --       137        --       169
    Other noncash...............................................................      (21)       35       (75)      (28)       79
    Gain on sale of oil and gas properties......................................     (110)     (112)       --        --       (40)
    Extraordinary loss resulting from extinguishment of debt....................       --        --        --        --     1,640
    Change in operating assets and liabilities:
      Increase in accounts receivable...........................................     (837)   (1,535)   (4,818)   (3,568)   (1,209)
      Decrease (increase) in other assets.......................................       20       301      (216)     (107)   (2,190)
      Increase in accounts payable..............................................      262       723     4,863     2,188      (880)
      Increase in other liabilities.............................................       59       102     1,537    (1,624)      671
      Increase (decrease) in deferred income....................................       (8)        3     3,294        --      (696)
                                                                                  -------  --------  --------  --------  --------
        Total adjustments.......................................................      249     1,364    10,680    (1,772)    2,164
                                                                                  -------  --------  --------  --------  --------
        Net cash provided by (used in) operating activities.....................      322     1,527     6,366    (3,040)     (122)
                                                                                  -------  --------  --------  --------  --------
Cash flows from investing activities:
  Capital expenditures for oil and gas properties...............................   (6,634)  (11,819)  (61,500)  (57,261)  (47,727)
  Proceeds from sale of oil and gas properties..................................      131       112        --        --        --
  Additions to other property and equipment.....................................     (228)      (49)     (720)     (512)   (1,996)
  Advances on affiliate notes receivable........................................       --      (390)     (247)       --        --
                                                                                  -------  --------  --------  --------  --------
        Net cash used in investing activities...................................   (6,731)  (12,146)  (62,467)  (57,773)  (49,723)
                                                                                  -------  --------  --------  --------  --------
Cash flows from financing activities:
  Borrowings under long-term debt...............................................    6,770    11,579    62,704    62,680   125,390
  Payments of long-term debt....................................................       --        --   (11,232)   (7,902)  (74,519)
  Deferred loan and financing costs.............................................       --        --    (2,587)   (2,587)   (2,728)
  Proceeds from redeemable members' capital.....................................       --        --    10,000    10,000        --
  Contributions.................................................................        1        --        --        --        --
  Withdrawals...................................................................     (456)     (961)      (55)      (97)       --
                                                                                  -------  --------  --------  --------  --------
        Net cash provided by financing activities...............................    6,315    10,618    58,830    62,094    48,143
                                                                                  -------  --------  --------  --------  --------
Net increase (decrease) in cash and cash equivalents............................      (94)       (1)    2,729     1,281    (1,702)
Cash and cash equivalents, beginning of period..................................      232       138       137       137     2,866
                                                                                  -------  --------  --------  --------  --------
Cash and cash equivalents, end of period........................................  $   138  $    137  $  2,866  $  1,418  $  1,164
                                                                                  -------  --------  --------  --------  --------
                                                                                  -------  --------  --------  --------  --------
</TABLE>
    
 
          See accompanying notes to consolidated financial statements.
 
                                      F-7
<PAGE>
                            COSTILLA ENERGY, L.L.C.
   
                      (A TEXAS LIMITED LIABILITY COMPANY)
    
 
                   NOTES TO CONSOLIDATED FINANCIAL STATEMENTS
 
        (THE INFORMATION AND AMOUNTS FOR INTERIM PERIODS ARE UNAUDITED.)
 
(1) ORGANIZATION AND NATURE OF OPERATIONS
    Costilla  Energy, L.L.C. (the "Company"), a Texas limited liability company,
was formed on  February 14,  1995, as  the successor  to CSL  Partners, a  Texas
general  partnership, which was organized on January 11, 1989. The Company is an
unincorporated association of  several individuals  and a  corporation and  will
cease  to exist thirty (30)  years from the date  of formation. Its members have
limited personal liability for the Company's obligations and debts. The  Company
is classified as a partnership for federal income tax purposes.
 
    The  Company  is an  oil  and gas  exploration  and production  concern with
properties located  principally  in  West  Texas, South  Texas,  and  the  Rocky
Mountain regions of the United States.
 
(2) SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES
 
    PRINCIPLES OF CONSOLIDATION
 
   
    As  of December 31, 1995, the  consolidated financial statements include the
accounts  of  the  Company  and  its  wholly-owned  subsidiaries.  The   Company
proportionately  consolidates less-than-100%-owned oil  and gas partnerships and
joint ventures in  accordance with industry  practice. All significant  accounts
and  transactions between the Company and its subsidiaries have been eliminated.
At December 31, 1993 and 1994, the  financial statements of the Company and  its
affiliates  were combined. Prior  to February 14,  1995, the combining companies
were owned by individuals who own 70% of the Company, in approximately the  same
proportion  relative to one  another as is  their current ownership. Significant
intercompany transactions were eliminated.
    
 
    USE OF ESTIMATES
 
    Preparation  of  the  accompanying  consolidated  financial  statements   in
conformity  with generally accepted accounting principles requires management to
make estimates and assumptions  that affect the reported  amounts of assets  and
liabilities  and disclosure of contingent assets  and liabilities at the date of
the financial  statements and  the  reported amounts  of revenues  and  expenses
during the reporting period. Actual results could differ from those estimates.
 
    CASH AND CASH EQUIVALENTS
 
    For  purposes of  the statements  of cash  flows, cash  and cash equivalents
include cash on hand and depository accounts held by banks.
 
    CONCENTRATIONS OF CREDIT RISK
 
    Financial instruments that potentially expose the Company to  concentrations
of   credit  risk  consist  primarily  of  unsecured  accounts  receivable  from
unaffiliated working interest owners and crude oil and natural gas purchasers.
 
   
    TRADE RECEIVABLES
    
 
   
    Trade receivables  generally consist  of amounts  due from  outside  working
interest  owners for their  proportionate share of  drilling and operating costs
incurred by the Company, as operator of the related properties.
    
 
    HEDGING
 
    Premiums  paid  for  commodity  option  contracts  and  interest  rate  swap
agreements   are  amortized  to   oil  and  gas   sales  and  interest  expense,
respectively, over  the  terms  of  the  agreements.  Unamortized  premiums  are
included  in other assets in the  consolidated balance sheet. Amounts receivable
under the  commodity option  contracts  and interest  rate swap  agreements  are
accrued as an increase in oil and gas sales and a reduction of interest expense,
respectively, for the applicable periods.
 
                                      F-8
<PAGE>
                            COSTILLA ENERGY, L.L.C.
   
                      (A TEXAS LIMITED LIABILITY COMPANY)
    
 
             NOTES TO CONSOLIDATED FINANCIAL STATEMENTS (CONTINUED)
 
        (THE INFORMATION AND AMOUNTS FOR INTERIM PERIODS ARE UNAUDITED.)
 
(2) SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES (CONTINUED)
    OIL AND GAS PROPERTIES
 
    The Company uses the successful efforts method of accounting for oil and gas
producing  activities.  Costs  to  acquire  mineral  interests  in  oil  and gas
properties, to drill and equip exploratory wells that find proved reserves,  and
to drill and equip development wells are capitalized. Costs to drill exploratory
wells  that do not  find proved reserves, geological  and geophysical costs, and
costs of carrying and retaining unproved properties are expensed.
 
   
    Unproved oil  and  gas  properties that  are  individually  significant  are
periodically  assessed for impairment of value, and  a loss is recognized at the
time  of  impairment  by  providing  an  impairment  allowance.  Other  unproved
properties  are  amortized  based  on  the  Company's  experience  of successful
drilling and average holding period. Capitalized costs of producing oil and  gas
properties,  after considering estimated dismantlement and abandonment costs and
estimated salvage values, are depreciated and depleted by the unit-of-production
method. Support equipment and other property and equipment are depreciated on  a
straight-line  basis over the estimated useful  lives of the assets, which range
from 5 to 7 years.
    
 
   
    Prior to the adoption of FAS 121 on January 1, 1995, the Company's aggregate
oil and gas properties were  carried at cost, not  in excess of total  estimated
undiscounted future net revenues, on a worldwide basis.
    
 
    On  sale or retirement of a complete unit of a proved property, the cost and
related accumulated  depreciation, depletion,  and amortization  are  eliminated
from  the property accounts,  and the resultant  gain or loss  is recognized. On
retirement or sale of a partial unit of proved property, the cost is charged  to
accumulated  depreciation, depletion, and amortization  with a resulting gain or
loss recognized in income.
 
    On sale of  an entire  interest in  an unproved  property for  cash or  cash
equivalent,  gain or loss  on the sale is  recognized, taking into consideration
the amount  of  any  recorded  impairment if  the  property  had  been  assessed
individually.  If a partial interest in an unproved property is sold, the amount
received is treated as a reduction of the cost of the interest retained.
 
    IMPAIRMENT OF LONG-LIVED ASSETS
 
    As of January 1,  1995, the Company adopted  the provisions of Statement  of
Financial  Accounting  Standards No.  121 --  ACCOUNTING  FOR THE  IMPAIRMENT OF
LONG-LIVED ASSETS  AND FOR  LONG-LIVED ASSETS  TO BE  DISPOSED OF  ("FAS  121").
Consequently,  the Company  reviews its long-lived  assets to be  held and used,
including oil  and gas  properties accounted  for under  the successful  efforts
method  of  accounting,  whenever  events  or  circumstances  indicate  that the
carrying value of  those assets may  not be recoverable.  An impairment loss  is
indicated if the sum of the expected future cash flows is less than the carrying
amount of the assets. In this circumstance, the Company recognizes an impairment
loss  for the amount by which the carrying  amount of the asset exceeds the fair
value of the asset.
 
    DEFERRED CHARGES
 
    The Company capitalized certain costs incurred in connection with  obtaining
the  Credit Agreement and  the related revolver  and term notes  (see Note 7 for
definitions and descriptions of each). These costs are being amortized over  the
lives of the notes.
 
    DEFERRED INCOME
 
    In  November 1995, the Company entered  into gas sales agreements whereby it
committed to  delivery of  a total  of 2,379,000  Mmbtu, from  December 1,  1995
through December 1, 1996, for a total fixed price of $3,429,610. Income from the
agreements is recognized in the period of delivery.
 
                                      F-9
<PAGE>
                            COSTILLA ENERGY, L.L.C.
   
                      (A TEXAS LIMITED LIABILITY COMPANY)
    
 
             NOTES TO CONSOLIDATED FINANCIAL STATEMENTS (CONTINUED)
 
        (THE INFORMATION AND AMOUNTS FOR INTERIM PERIODS ARE UNAUDITED.)
 
(2) SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES (CONTINUED)
    REVENUE RECOGNITION
 
   
    The  Company uses  the sales  method of  accounting for  crude oil revenues.
Under this method, revenues are recognized  based on actual volumes of oil  sold
to purchasers.
    
 
   
    The  Company  uses the  entitlements method  of  accounting for  natural gas
revenues. Under this method, revenues are recognized based on actual  production
of  natural gas. Natural gas revenues  would not have been significantly altered
in any period  had the  sales method of  recognizing natural  gas revenues  been
utilized.
    
 
    ENVIRONMENTAL
 
    The  Company is subject to extensive  Federal, state and local environmental
laws and regulations. These  laws, which are  constantly changing, regulate  the
discharge  of  materials into  the environment  and may  require the  Company to
remove or  mitigate the  environmental effects  of the  disposal or  release  of
petroleum  or chemical  substances at various  sites. Environmental expenditures
are  expensed  or  capitalized  depending  on  their  future  economic  benefit.
Expenditures  that relate to an existing condition caused by past operations and
that have no future economic benefits are expensed. Liabilities for expenditures
of a  noncapital  nature are  recorded  when environmental  assessment  and/  or
remediation is probable, and the costs can be reasonably estimated.
 
    RECLASSIFICATIONS
 
    Certain  reclassifications have  been made  to the  1993 and  1994 financial
statements to conform to the 1995 presentation.
 
    INTERIM FINANCIAL STATEMENTS
 
   
    The interim  financial information  as of  June 30,  1996, and  for the  six
months  ended June 30, 1995  and 1996, is unaudited.  However, in the opinion of
management,  these  interim  financial  statements  include  all  the  necessary
adjustments  to fairly present the results of  the interim periods, and all such
adjustments are of a normal  recurring nature. The interim financial  statements
should  be read  in conjunction  with the  audited financial  statements for the
years ended December 31, 1993, 1994 and 1995.
    
 
(3) ACQUISITION OF OIL AND GAS PROPERTIES
   
    On June 12, 1995, the Company  completed the acquisition of certain oil  and
gas  properties and  related assets from  Parker & Parsley  Development L.P. and
Parker & Parsley Producing L.P.  for $46,621,371. The transaction was  accounted
for  using  the  purchase method.  The  results  of operations  of  the acquired
properties are included in the  Consolidated Statements of Operations  beginning
June  12, 1995.  The Company funded  the acquisition under  the Credit Agreement
described in Note (7).  Certain of the acquired  properties, which were  located
outside of the Company's areas of strategic focus, were sold in 1995. No gain or
loss was recorded on these sales.
    
 
   
    PRO FORMA RESULTS OF OPERATIONS (UNAUDITED)
    
 
   
    The  following table reflects the pro  forma results of operations as though
the acquisition, net of the related properties sold, had occurred on January  1,
1994.  The pro forma amounts are not  necessarily indicative of the results that
may be reported in the future.
    
 
   
<TABLE>
<CAPTION>
                                                                           YEARS ENDED DECEMBER
                                                                                   31,
                                                                             1994       1995
                                                                           ---------  ---------
                                                                              (IN THOUSANDS)
<S>                                                                        <C>        <C>
Revenues.................................................................     35,460     32,746
Net income (loss)........................................................      1,563     (3,999)
</TABLE>
    
 
                                      F-10
<PAGE>
                            COSTILLA ENERGY, L.L.C.
   
                      (A TEXAS LIMITED LIABILITY COMPANY)
    
 
             NOTES TO CONSOLIDATED FINANCIAL STATEMENTS (CONTINUED)
 
        (THE INFORMATION AND AMOUNTS FOR INTERIM PERIODS ARE UNAUDITED.)
 
(4) IMPAIRMENT OF LONG-LIVED ASSETS
    The Company  adopted  FAS 121  effective  as of  January  1, 1995.  FAS  121
requires  that long-lived assets held  and used by an  entity, including oil and
gas properties accounted for under the successful efforts method of  accounting,
be  reviewed for impairment whenever events or changes in circumstances indicate
that the carrying amount of an  asset may not be recoverable. Long-lived  assets
to  be disposed of  are to be accounted  for at the lower  of carrying amount or
fair value less cost to sell when management has committed to a plan to  dispose
of  the  assets.  All  companies,  including  successful  efforts  oil  and  gas
companies, are  required to  adopt  FAS 121  for  fiscal years  beginning  after
December 15, 1995.
 
    In  order  to  determine whether  an  impairment had  occurred,  the Company
estimated the  expected future  cash flows  of its  oil and  gas properties  and
compared  such  future cash  flows to  the carrying  amount of  the oil  and gas
properties to determine if  the carrying amount was  recoverable. Based on  this
process,  no writedown in the carrying amount of the Company's proved properties
was necessary at December 31, 1995.
 
(5) DERIVATIVE FINANCIAL INSTRUMENTS
    The Company utilizes derivative financial instruments to manage well-defined
interest rate and commodity price risks. The Company is exposed to credit losses
in the event of nonperformance by  the counterparties to its interest rate  swap
agreements and its commodity hedges. The Company anticipates, however, that such
counterparties  will  be  able  to fully  satisfy  their  obligations  under the
contracts. The Company does not obtain  collateral or other security to  support
financial instruments subject to credit risk but monitors the credit standing of
the counterparties.
 
   
    COMMODITY HEDGES.  The Company utilizes option contracts to hedge the effect
of  price changes on future oil and gas  production. If market prices of oil and
gas exceed the strike price of put options, the options will expire unexercised,
therefore reducing the  effective price received  for oil and  gas sales by  the
cost  of the related option.  The following table sets  forth the future volumes
hedged by year and the weighted-average strike price of the option contracts  at
December 31, 1995:
    
 
<TABLE>
<CAPTION>
                                                           OIL          GAS
                                                         VOLUME       VOLUME         STRIKE PRICE
                                                         (BBLS)       (MMBTU)        PER BBL/MMBTU
                                                       -----------  -----------  ---------------------
<S>                                                    <C>          <C>          <C>
Oil:
  1996...............................................    1,830,000           --   $16.00 - $20.38(a)
  1997...............................................      912,500           --   $16.00 - $20.65(a)
Gas:
  1996...............................................           --    1,500,000        $1.65(b)
  1997...............................................           --    1,350,000        $1.65(b)
</TABLE>
 
- ------------------------
(a) Represents  the  weighted-average  price  of  collars  established  with the
    purchase of put option contracts and the sale of call option contracts.
 
(b) Represents the strike price on purchased put option contracts.
 
   
    INTEREST RATE  SWAP AGREEMENTS.   The  Company utilizes  interest rate  swap
agreements  to reduce  the potential  impact of  increases in  interest rates on
floating-rate, long-term debt.  If market rates  of interest experienced  during
the  applicable swap term are  below the rates of  interest effectively fixed by
the swap agreement, the rate of interest experienced by the Company will  exceed
the  rate  that  would have  been  experienced  under the  Credit  Agreement. At
December 31, 1995, the Company was a
    
 
                                      F-11
<PAGE>
                            COSTILLA ENERGY, L.L.C.
   
                      (A TEXAS LIMITED LIABILITY COMPANY)
    
 
             NOTES TO CONSOLIDATED FINANCIAL STATEMENTS (CONTINUED)
 
        (THE INFORMATION AND AMOUNTS FOR INTERIM PERIODS ARE UNAUDITED.)
 
(5) DERIVATIVE FINANCIAL INSTRUMENTS (CONTINUED)
party to two interest rate swap  agreements, providing the Company with a  fixed
interest  rate for the terms  of the agreements. The  following table sets forth
the terms, fixed rates, and  notional amounts of the  agreements in place as  of
December 31, 1995:
 
<TABLE>
<CAPTION>
                                        NOTIONAL
                                        PRINCIPAL                 FIXED
                TERM                     AMOUNT               INTEREST RATE
- ------------------------------------  -------------  -------------------------------
<S>                                   <C>            <C>
Jan. 25, 1996 to Jan. 25, 1999         $24 million      ranging from 7.5% to 8.5%
May 24, 1995 to May 27, 1997           $60 million                5.99%
</TABLE>
 
(6) FAIR VALUE OF FINANCIAL INSTRUMENTS
    The  following table presents the carrying amounts and estimated fair values
of the  Company's financial  instruments at  December 31,  1994 and  1995.  FASB
Statement  No.  107,  DISCLOSURES  ABOUT FAIR  VALUE  OF  FINANCIAL INSTRUMENTS,
defines the fair  value of a  financial instrument  as the amount  at which  the
instrument could be exchanged in a current transaction between willing parties.
 
   
<TABLE>
<CAPTION>
                                                                             1994                  1995
                                                                     --------------------  --------------------
                                                                     CARRYING     FAIR     CARRYING     FAIR
                                                                      AMOUNT      VALUE     AMOUNT      VALUE
                                                                     ---------  ---------  ---------  ---------
<S>                                                                  <C>        <C>        <C>        <C>
                                                                                   (IN THOUSANDS)
Financial assets:
  Cash, cash equivalents and restricted cash.......................  $     137  $     137  $   2,866  $   2,866
  Receivables (trade)..............................................      1,042      1,042      3,154      3,154
  Receivables (oil and gas sales)..................................      1,715      1,715      3,915      3,915
  Commodity option contracts.......................................         --         --        165        555
  Interest rate swap and option agreements.........................        203         --        146     (2,970)
  Notes receivable -- affiliate....................................        390        390        684        684
Financial liabilities:
  Payables (trade).................................................      1,712      1,712      5,467      5,467
  Deferred income..................................................         --         --      3,319      2,950
  Long-term debt...................................................     23,613     23,613     71,494     71,494
</TABLE>
    
 
    The  carrying amounts shown  in the table  are included in  the statement of
financial position under the indicated captions.
 
    The following methods and assumptions were  used to estimate the fair  value
of each class of financial instruments:
 
    CASH,   TRADE  RECEIVABLES,  AND  TRADE  PAYABLES:    The  carrying  amounts
approximate fair value because of the short maturity of those instruments.
 
    OTHER CURRENT ASSETS:  The amounts  reported relate to the commodity  option
contracts  and interest rate  swap agreements described in  Note 5. The carrying
amount comprises the unamortized premiums paid for the contracts. The fair value
is estimated using option  pricing models and  essentially values the  potential
for  the  contracts and  agreements to  become  in-the-money through  changes in
commodity prices and interest rates during the remaining terms.
 
    NOTES RECEIVABLE-AFFILIATE:  The amounts reported relate to notes receivable
from an affiliated company. The carrying amount approximates fair value  because
the  rate given to  the affiliate company  is not materially  different from the
affiliate company's bank debt.
 
                                      F-12
<PAGE>
                            COSTILLA ENERGY, L.L.C.
   
                      (A TEXAS LIMITED LIABILITY COMPANY)
    
 
             NOTES TO CONSOLIDATED FINANCIAL STATEMENTS (CONTINUED)
 
        (THE INFORMATION AND AMOUNTS FOR INTERIM PERIODS ARE UNAUDITED.)
 
(6) FAIR VALUE OF FINANCIAL INSTRUMENTS (CONTINUED)
    DEFERRED INCOME:  The amounts reported relate to the gas purchase agreements
described in Note 2. The carrying amount represents the payments received  under
the  agreements for  which subsequent  delivery is  required. The  fair value is
estimated based upon  the commodity price  at December 31,  1995, for a  similar
agreement.
 
    LONG-TERM DEBT:  The fair value of the Company's long-term debt is estimated
by discounting expected cash flows at the rates currently offered to the Company
for debt of the same remaining maturities, as advised by the Company's bankers.
 
(7) LONG-TERM DEBT
   
    Long-term debt consists of the following:
    
 
   
<TABLE>
<CAPTION>
                                                                             DECEMBER 31,
                                                                         --------------------
                                                                           1994       1995
                                                                         ---------  ---------
                                                                            (IN THOUSANDS)
<S>                                                                      <C>        <C>
Revolver note..........................................................  $      --  $  59,824
Term notes.............................................................         --     11,670
Note payable to bank...................................................     23,591         --
Note payable to member.................................................         22         --
                                                                         ---------  ---------
                                                                            23,613     71,494
    Less current maturities............................................         22         --
                                                                         ---------  ---------
                                                                         $  23,591  $  71,494
                                                                         ---------  ---------
                                                                         ---------  ---------
</TABLE>
    
 
    At  December  31, 1995,  the  Company and  certain  of its  subsidiaries are
parties to  a Credit  Agreement with  a syndicate  of banks  (the "Banks").  The
Credit Agreement provides for an aggregate $185 million senior secured revolving
line  of credit  ("Revolver Notes")  and an aggregate  of $15  million in senior
secured term notes ("Term Notes"). All notes are secured with the assets of  the
Company  and  are guaranteed  by the  Company's subsidiaries  and, to  a limited
extent, its individual members.
 
    The Revolver Notes  and Term  Notes are  subject to  an aggregate  borrowing
base, as determined by the Banks or their agents in their sole discretion and is
redetermined  at least bi-annually as  of January 15 and  July 15, utilizing oil
and gas reserve information  as of the immediately  preceding period end. As  of
January 15, 1996, the borrowing base was $71,670,000.
 
    All  outstanding balances under  the Credit Agreement  may be designated, at
the Company's option, as  either "Base Rate Portions"  or "Fixed Rate  Portions"
(both  as defined  in the  Credit Agreement),  provided that  no more  than five
Eurodollar Tranches may be  outstanding at any time.  The Base Rate Portions  of
the  Revolver Notes bear interest at the  fluctuating Base Rate, plus a Revolver
Base Rate Spread  ranging from 0.25%  to 0.75%, depending  upon the  outstanding
principal  balances of the Term Notes. The  Base Rate Portions of the Term Notes
bear interest at the fluctuating Base  Rate plus 0.75%. The Fixed Rate  Portions
of the Revolver Notes bear interest at the Eurodollar Rate for a fixed period of
time  elected by  the Company,  plus a Revolver  Fixed Rate  Spread ranging from
2.25% to 3.00%,  depending on  the outstanding  principal balances  of the  Term
Notes. The Fixed Rate Portions of the Term Notes bear interest at the Eurodollar
Rate for a fixed period of time elected by the Company, plus a Fixed Rate Spread
of 3.00%. As of December 31, 1995, the Company had elected a fixed rate of 8.82%
for  the Revolver Notes and had elected  fixed rates ranging from 8.82% to 8.94%
for $14,000,000  of  the  outstanding  Term Notes  at  December  31,  1995.  The
remaining  balances  of  the  Term  Notes bear  interest  at  the  Base  Rate of
NationsBank Prime plus 1.50% at December 31, 1995.
 
                                      F-13
<PAGE>
                            COSTILLA ENERGY, L.L.C.
   
                      (A TEXAS LIMITED LIABILITY COMPANY)
    
 
             NOTES TO CONSOLIDATED FINANCIAL STATEMENTS (CONTINUED)
 
        (THE INFORMATION AND AMOUNTS FOR INTERIM PERIODS ARE UNAUDITED.)
 
(7) LONG-TERM DEBT (CONTINUED)
    The outstanding principal balance of the  Revolver Notes is due and  payable
in  sixty (60)  monthly installments  beginning August  1, 1996,  and continuing
regularly thereafter until July  1, 2001. The  outstanding principal balance  of
the  Term Notes is due and payable in  two (2) installments, each of which shall
be equal to one-half of  the unpaid principal balance of  each note, on July  1,
1996, and January 1, 1997.
 
    The  Credit Agreement requires the Company to hedge not less than 60% of the
Company's total  sales  volume,  through  December 31,  1997,  from  its  proved
developed  producing oil and gas  reserves, with a floor  price of not less than
$16 per Bbl of oil or $1.50 per Mcf of gas.
 
    Additionally, the Credit  Agreement contains  various restrictive  covenants
and  compliance requirements, which  include: (a) restrictions  on dividends and
the incurrence of additional indebtedness;  (b) restrictions as to merger,  sale
or  transfer of  assets; (c) limiting  total lease payments  and total aggregate
executive compensation to  $750,000 and  $500,000, respectively,  in any  fiscal
year; and (d) compliance with certain financial ratios.
 
    The   Company  was  in   violation  of  certain   covenants  and  compliance
requirements as of  December 31,  1995. Subsequent  to December  31, 1995,  such
violations were waived by the Banks.
 
    Maturities  of  long-term debt  at  December 31,  1995,  are as  follows (in
thousands):
 
<TABLE>
<S>                                                         <C>
1996......................................................  $  10,820
1997......................................................     17,800
1998......................................................     11,965
1999......................................................     11,965
2000......................................................     11,965
Thereafter................................................      6,979
</TABLE>
 
    The Company  paid interest  on long-term  debt of  $546,147, $1,356,604  and
$4,453,684 in 1993, 1994 and 1995, respectively.
 
   
    As  described in  Note 12,  on June 10,  1996, the  Company demonstrated its
intent and  ability  to  refinance  the  current  maturities  under  the  Credit
Agreement  by entering into a new loan agreement, proceeds of which were used to
repay the existing notes. Concurrently, the deferred charges associated with the
Credit Agreement were expensed as an extraordinary loss.
    
 
(8) COMMITMENTS AND CONTINGENCIES
 
    LEASES
 
    The Company leases equipment and office facilities under operating leases on
which rental expense for the years ended  December 31, 1993, 1994 and 1995,  was
$110,023,  $197,533 and $311,221, respectively. Future minimum lease commitments
under noncancellable operating leases at December  31, 1995, are as follows  (in
thousands):
 
<TABLE>
<S>                                                          <C>
1996.......................................................  $     257
1997.......................................................        272
1998.......................................................        268
1999.......................................................        195
2000.......................................................        188
Thereafter.................................................      1,190
</TABLE>
 
    SEVERANCE AGREEMENTS
 
    On  February 17, 1995,  the Company entered  into employment agreements with
each of the officers  which are effective from  the above date through  February
17, 2000, or until terminated by the
 
                                      F-14
<PAGE>
                            COSTILLA ENERGY, L.L.C.
   
                      (A TEXAS LIMITED LIABILITY COMPANY)
    
 
             NOTES TO CONSOLIDATED FINANCIAL STATEMENTS (CONTINUED)
 
        (THE INFORMATION AND AMOUNTS FOR INTERIM PERIODS ARE UNAUDITED.)
 
(8) COMMITMENTS AND CONTINGENCIES (CONTINUED)
officer  or the  Company. In  addition to  providing a  base salary  and nominal
yearly increases  for  each  officer,  the  employment  agreements  provide  for
severance  payments  upon  termination of  any  such officer's  employment  or a
significant reduction in that officer's duties or responsibilities.
 
    In the event  of such a  termination, the  Company is obligated  to pay  the
officer  an  amount  equal to  the  present  value (discounted  at  10%)  of the
officer's salary  which would  have been  paid through  February 17,  2000.  The
current  annual base  salaries for  the officers  covered under  such employment
agreements total approximately $500,000.
 
   
    EXPLORATION AND DEVELOPMENT
    
 
   
    In July 1995,  the Republic of  Moldova (located in  Eastern Europe  between
Romania  and the Ukraine) granted a Concession Agreement to Resource Development
Company Limited, L.L.C. ("Redeco"), an  entity not affiliated with the  Company.
The Company has paid Redeco $90,000 and agreed to bear the first $2.0 million of
Concession  expenses ($214,178 of  which had been  expended through December 31,
1995) in return for a 50.0% interest  in Redeco. After the initial $2.0  million
expenditure,  Redeco and the  Company are responsible for  bearing 50.0% each of
future expenses. The Concession Agreement covers the entire country with respect
to oil  and  gas and  other  minerals and  continues  for various  time  periods
depending  on  the nature  of  the activity  conducted.  In connection  with two
previously  producing  but  now  abandoned  fields,  Redeco's  exclusive  rights
continue  for  20 years.  Redeco's exclusive  period  to explore  throughout the
remainder of  Moldova  expires  in  2005, but  Redeco  will  maintain  exclusive
development  rights with respect to  fields discovered for a  period of 20 years
from the date of first production from  such field. The Company has no  material
fixed financial commitments with respect to the Concession.
    
 
    LETTERS OF CREDIT
 
    As  a result of certain bonding and trade creditor requirements, the Company
has caused  irrevocable  letters of  credit  to be  issued  by a  bank  totaling
$106,000. As of December 31, 1995, no amounts had been drawn on these letters of
credit.
 
(9) 401(K) PLAN
    The  Company has established a qualified  cash or deferred arrangement under
IRS code section 401(k)  covering substantially all  employees. Under the  plan,
the  employees have  an option  to make elective  contributions of  a portion of
their eligible compensation, not to exceed specified annual limitations, to  the
plan  and the  Company has  an option  to match  a percentage  of the employee's
contribution. The Company has made  matching contributions to the plan  totaling
$16,950, $8,921 and $22,531 in 1993, 1994 and 1995, respectively.
 
(10) REDEEMABLE MEMBERS' CAPITAL AND MEMBERS' CAPITAL
   
    During  1995,  NationsBanc  Capital  Corporation  ("NBCC")  contributed  $10
million in exchange for  a 30% ownership interest  in the Company including  the
preferential return described below. The Company incurred $751,737 in legal fees
and  broker's commissions in connection with this transaction and recorded these
costs as direct charges to members' capital in 1995.
    
 
   
    Redeemable members'  capital  includes  $10,000,000 that  is  subject  to  a
preferential  return  of 15%  per annum  and is  redeemable at  any time  at the
Company's option, subject  to a  redemption premium  as described  below, or  at
NBCC's  option on  February 17, 2003  or at  an earlier date  upon occurrence of
certain events including a change in  control, certain changes in management,  a
change  in the Company's status as a limited liability company for tax purposes,
or violation of  any of various  other restrictive provisions  contained in  the
Regulations    of   Costilla    Energy,   L.L.C.    (the   "Regulations").   The
    
 
                                      F-15
<PAGE>
                            COSTILLA ENERGY, L.L.C.
   
                      (A TEXAS LIMITED LIABILITY COMPANY)
    
 
             NOTES TO CONSOLIDATED FINANCIAL STATEMENTS (CONTINUED)
 
        (THE INFORMATION AND AMOUNTS FOR INTERIM PERIODS ARE UNAUDITED.)
 
(10) REDEEMABLE MEMBERS' CAPITAL AND MEMBERS' CAPITAL (CONTINUED)
15% preferred  return  is  treated  as a  reduction  of  members'  capital.  The
redemption  price to be paid by the Company shall be equal to the initial amount
received for the  preferred units  plus a premium,  determined in  the year  the
units are purchased, as follows:
 
<TABLE>
<CAPTION>
      YEAR AFTER            PREMIUM
   FEBRUARY 17, 1995      PERCENTAGE
- -----------------------  -------------
<S>                      <C>
               1                  10%
               2                  10%
               3                   8%
               4                   6%
               5                   4%
               6                   2%
               7                   0%
               8                   0%
</TABLE>
 
   
    In addition, a portion of NBCC's interest not subject to preferential return
is  classified as redeemable members' capital as  the Company may be required to
repurchase such interest upon the occurrence of certain events similar to  those
events  requiring redemption of the  redeemable members' capital described above
and, in any  event, on or  after February 17,  2000. Such interest  may, at  the
Company's  option, be  repurchased to the  extent the Company  has exercised its
right to redeem all or a portion of the redeemable members' interest subject  to
the  preferential return. The  redemption price the Company  would pay in either
instance is determined by the year in which the members' capital is repurchased,
as follows:
    
 
<TABLE>
<CAPTION>
                                                                       AGGREGATE
BEFORE FEBRUARY 17                                                  REDEMPTION PRICE
- ------------------------------------------------------------------  ----------------
<S>                                                                 <C>
1996..............................................................   $            1
1997..............................................................        1,500,000
1998..............................................................        3,000,000
1999..............................................................        4,500,000
2000..............................................................        5,500,000
</TABLE>
 
   
    The ultimate redemption price  of $5,500,000 is  being accrued ratably  over
the  period from February 17, 1995 through February 17, 2000 and is treated as a
reduction of members' capital.
    
 
   
    NBCC would  retain an  18% interest  in the  Company after  the  redemptions
described above occur. Such interest is not subject to redemption.
    
 
    At  December 31, 1995,  the Company was in  violation of various restrictive
provisions of the Regulations. Subsequent to December 31, 1995, NBCC waived such
violations.
 
(11) RELATED PARTY TRANSACTIONS
    Certain members  and officers  of  the Company  own  interests in  and  hold
positions  with  A&P  Meter Service  and  Supply, Inc.  ("A&P"),  CSL Management
Corporation ("CSL"),  511 Tex  L.C.  ("511 Tex")  and Valley  Gathering  Company
("Valley").
 
    Advances  from the Company to A&P have been consolidated into two promissory
notes. The first note, which was  originally executed December 31, 1994,  totals
$390,000,  including accrued interest of $20,000  at December 31, 1995. The note
bears interest  at a  floating rate  equal to  the "prime  rate" plus  1.0%.  No
principal  or  interest payments  are  due until  the  maturity of  the  note at
December 31,  2004. The  note is  secured by  a second  lien on  A&P's  accounts
receivable, inventory and equipment. The
 
                                      F-16
<PAGE>
                            COSTILLA ENERGY, L.L.C.
   
                      (A TEXAS LIMITED LIABILITY COMPANY)
    
 
             NOTES TO CONSOLIDATED FINANCIAL STATEMENTS (CONTINUED)
 
        (THE INFORMATION AND AMOUNTS FOR INTERIM PERIODS ARE UNAUDITED.)
 
(11) RELATED PARTY TRANSACTIONS (CONTINUED)
second note is in the amount of $294,000, including accrued interest of $47,000,
and  is  dated May  22, 1996.  The note  bears  interest at  6.0% per  annum, is
unsecured and is payable upon demand. During 1995, the Company paid $612,139  to
A&P for goods and services provided.
 
    During  1993,  1994  and  1995,  the  Company  paid  $312,623,  $549,620 and
$592,920, respectively,  to  CSL  for  management fees  and  lease  payments  on
equipment.
 
    During 1995, the Company paid $67,896 to 511 Tex for office rent.
 
    During 1994 and 1995, the Company paid $2,458 and $440,884, respectively, to
Valley  for gas compression and salt water disposal charges. During 1995, Valley
paid the Company $109,399 for operating  costs of its salt water disposal  wells
and gas compressors.
 
(12) SUBSEQUENT EVENTS
   
    On  March 8, 1996, the  Company executed a Purchase  and Sale Agreement with
Parker and Parsley Petroleum Company to  acquire certain oil and gas  properties
for  an estimated  adjusted purchase price  of approximately  $42.5 million. The
properties are located primarily  in south and west  Texas. The transaction  was
accounted  for  using the  purchase  method. The  results  of operations  of the
acquired properties are included in the Consolidated Statements of Operations as
of the closing date, June 14, 1996.
    
 
   
    PRO FORMA RESULTS OF OPERATIONS (UNAUDITED)
    
 
   
    The following table  reflects the pro  forma results of  operations for  the
six-months  ended June  30, 1995  and 1996,  as though  both acquisitions, which
closed on June 12, 1995 and June 14,  1996, had occurred as of January 1,  1995.
The  pro forma amounts are not necessarily indicative of the results that may be
reported in the future.
    
 
   
<TABLE>
<CAPTION>
                                                                           SIX MONTHS ENDED
                                                                               JUNE 30,
                                                                         --------------------
                                                                           1995       1996
                                                                         ---------  ---------
                                                                            (IN THOUSANDS)
<S>                                                                      <C>        <C>
Revenues...............................................................  $  25,706  $  28,748
Net loss...............................................................     (2,875)      (910)
</TABLE>
    
 
    In connection  with the  foregoing,  the Company  entered  into a  new  loan
agreement  with  NationsBridge L.L.C.,  an  affiliate of  the  Company's current
lender, to provide financing  of up to $125  million in advances (the  "Loans"),
subject to certain terms and conditions. Proceeds of the Loans were used to fund
the  Acquisition, to  refinance substantially  all of  the Company's outstanding
indebtedness, and for other general corporate purposes.
 
    Advances under the Loans were to be  made in two portions, Tranche A was  up
to  $95,000,000  and  Tranche  B  was  $30,000,000.  Tranche  A  initially bears
interest, at the Company's option, at  the applicable prime rate ("Prime")  plus
0.75%  or LIBOR plus 3.0%. Each margin  above Prime and LIBOR increases by 0.50%
at the end of each successive three-month  period, up to a maximum of 2.75%  and
5.0%  for Prime and  LIBOR, respectively. Tranche B  initially bears interest at
14.00% per annum,  increasing 0.50% at  the end of  each successive  three-month
period, up to a maximum of 16.5%.
 
    Tranche  A loans are subject to  a borrowing base determination. The initial
borrowing base is $95,000,000 which  is automatically reduced by $3,000,000  per
quarter beginning January 1, 1997.
 
                                      F-17
<PAGE>
                            COSTILLA ENERGY, L.L.C.
   
                      (A TEXAS LIMITED LIABILITY COMPANY)
    
 
             NOTES TO CONSOLIDATED FINANCIAL STATEMENTS (CONTINUED)
 
        (THE INFORMATION AND AMOUNTS FOR INTERIM PERIODS ARE UNAUDITED.)
 
(12) SUBSEQUENT EVENTS (CONTINUED)
The  borrowing base is also subject to periodic redetermination by NationsBridge
L.L.C. based on its determination of  the collateral value of the Company's  oil
and  gas properties. Final maturity of loans made under Tranches A and B is June
10, 1999.
 
    The Loans  are secured  by first  priority liens,  assignments and  security
interests  in all oil and gas properties, pipelines and gathering systems of the
Company and stock  of the  Company's subsidiaries. Additionally,  the Loans  are
subject  to various restrictive covenants and compliance requirements, including
but not  limited  to  (a)  restrictions  on  dividends  and  the  incurrence  of
additional  indebtedness, (b) minimum limitations on the Company's current ratio
and tangible net  worth, (c) limitations  on payments for  leases and  executive
compensation,  (d) maximum  limitations on general  and administrative expenses,
capital expenditures and the Company's ratio of debt to adjusted cash flow,  and
(e)  a requirement to pay to the lender all net oil and gas revenues (as defined
and as adjusted for capital expenditures) on a quarterly basis.
 
   
    The Company paid the lender's fees and expenses in connection with obtaining
the Loans.  The fees  were  approximately $2,625,000  and  will increase  by  an
additional  $625,000 if the Tranche B Loans  remain outstanding for more than 90
days. In addition, if the Tranche B  amounts are not repaid within one year,  an
additional  amount  of  $4,800,000  will accrue.  If  such  additional  fees are
incurred, they will be  amortized over the remaining  period that the Loans  are
expected to be outstanding.
    
 
(13) OIL AND GAS EXPENDITURES
    The  following  table  reflects  costs  incurred  in  oil  and  gas property
acquisition, exploration and development activities:
 
   
<TABLE>
<CAPTION>
                                                                     YEARS ENDED DECEMBER 31,       THREE MONTHS
                                                                  -------------------------------  ENDED MARCH 31,
                                                                    1993       1994       1995          1996
                                                                  ---------  ---------  ---------  ---------------
                                                                          (IN THOUSANDS)             (UNAUDITED)
<S>                                                               <C>        <C>        <C>        <C>
Property acquisition costs:
  Proved........................................................  $   4,665  $   9,649  $  52,470     $   2,246
  Unproved......................................................        829      1,232      1,742           677
Exploration.....................................................      2,017      2,167      5,627         1,822
Development.....................................................         --         --        158           232
                                                                  ---------  ---------  ---------       -------
                                                                  $   7,511  $  13,048  $  59,997     $   4,977
                                                                  ---------  ---------  ---------       -------
                                                                  ---------  ---------  ---------       -------
</TABLE>
    
 
(14) SUPPLEMENTAL OIL AND GAS RESERVE INFORMATION (UNAUDITED)
    The estimates of proved oil and gas reserves, which are located  principally
in the United States, were prepared by the Company as of December 31, 1993, 1994
and  1995, and Williamson  Petroleum Consultants as of  March 31, 1996. Reserves
were estimated in  accordance with guidelines  established by the  SEC and  FASB
which  require that  reserve estimates be  prepared under  existing economic and
operating conditions with no provision for price and cost escalations, except by
contractual arrangements.  The  Company  has  presented  the  reserve  estimates
utilizing  an oil price of $17.79 per Bbl and a gas price of $2.03 per Mcf as of
December 31, 1995, and an oil price of  $20.71 per Bbl and a gas price of  $2.00
per Mcf as of March 31, 1996.
 
                                      F-18
<PAGE>
   
                            COSTILLA ENERGY, L.L.C.
                      (A TEXAS LIMITED LIABILITY COMPANY)
    
 
   
             NOTES TO CONSOLIDATED FINANCIAL STATEMENTS (CONTINUED)
    
        (THE INFORMATION AND AMOUNTS FOR INTERIM PERIODS ARE UNAUDITED.)
 
   
(14) SUPPLEMENTAL OIL AND GAS RESERVE INFORMATION (UNAUDITED) (CONTINUED)
    
 
    OIL AND GAS PRODUCING ACTIVITIES
 
    Oil and gas reserve quantity estimates are subject to numerous uncertainties
inherent  in  the  estimation  of  quantities  of  proved  reserves  and  in the
projection  of  future  rates  of  production  and  the  timing  of  development
expenditures.  The accuracy of  such estimates is  a function of  the quality of
available data and  of engineering and  geological interpretation and  judgment.
Results  of subsequent drilling, testing and  production may cause either upward
or downward revision of previous  estimates. Further, the volumes considered  to
be  commercially  recoverable fluctuate  with  changes in  prices  and operating
costs. The Company  emphasizes that reserve  estimates are inherently  imprecise
and that estimates of new discoveries are more imprecise than those of currently
producing  oil and gas properties. Accordingly,  these estimates are expected to
change as additional information becomes available in the future.
 
<TABLE>
<CAPTION>
                                                                                 OIL AND CONDENSATE       GAS
                                                                                       (MBBLS)          (MMCF)
                                                                                 -------------------  -----------
<S>                                                                              <C>                  <C>
Total Proved Reserves:
Balance, January 1, 1993.......................................................           1,985           16,418
  Revisions of previous estimates..............................................              57            1,160
  Extensions and discoveries...................................................             380              591
  Production...................................................................            (158)            (865)
  Purchases of minerals-in-place...............................................             101            4,315
                                                                                        -------       -----------
Balance, December 31, 1993.....................................................           2,365           21,619
  Revisions of previous estimates..............................................            (460)          (5,424)
  Extensions and discoveries...................................................             761            1,520
  Production...................................................................            (330)          (1,600)
  Purchases of minerals-in-place...............................................           1,673           11,397
                                                                                        -------       -----------
Balance, December 31, 1994.....................................................           4,009           27,512
  Revisions of previous estimates..............................................            (570)             425
  Extensions and discoveries...................................................             605            8,922
  Production...................................................................            (950)          (4,806)
  Purchases of minerals-in-place...............................................           7,694           46,099
                                                                                        -------       -----------
Balance, December 31, 1995.....................................................          10,788           78,152
  Revisions of previous estimates..............................................             437            2,615
  Extensions and discoveries...................................................             592              296
  Production...................................................................            (338)          (1,643)
  Purchases of minerals-in-place...............................................              --               --
                                                                                        -------       -----------
Balance, March 31, 1996........................................................          11,479           79,420
                                                                                        -------       -----------
                                                                                        -------       -----------
Proved Developed Reserves:
  January 1, 1993..............................................................           1,488           10,055
  December 31, 1993............................................................           1,785           13,268
  December 31, 1994............................................................           2,632           16,340
  December 31, 1995............................................................           8,566           57,393
  March 31, 1996...............................................................           9,037           55,408
</TABLE>
 
                                      F-19
<PAGE>
   
                            COSTILLA ENERGY, L.L.C.
                      (A TEXAS LIMITED LIABILITY COMPANY)
    
 
   
             NOTES TO CONSOLIDATED FINANCIAL STATEMENTS (CONTINUED)
    
        (THE INFORMATION AND AMOUNTS FOR INTERIM PERIODS ARE UNAUDITED.)
 
   
(14) SUPPLEMENTAL OIL AND GAS RESERVE INFORMATION (UNAUDITED) (CONTINUED)
    
 
    STANDARDIZED MEASURE OF DISCOUNTED FUTURE NET CASH FLOWS RELATING TO PROVED
OIL AND GAS RESERVES
 
    The standardized measure of discounted future net cash flows is computed  by
applying  year-end prices  of oil and  gas (with consideration  of price changes
only to the extent provided by contractual arrangements) to the estimated future
production of proved oil  and gas reserves,  less estimated future  expenditures
(based  on year-end costs) to be incurred in developing and producing the proved
reserves, less estimated future income tax expenses (based on year-end statutory
tax rates, with  consideration of  future tax  rates already  legislated) to  be
incurred  on  pretax  net cash  flows,  less  tax basis  of  the  properties and
available credits, and  assuming continuation of  existing economic  conditions.
The  estimated future net cash flows are then discounted using a rate of 10% per
year to reflect the estimated timing of the future cash flows.
 
    Discounted future  cash  flow  estimates  like those  shown  below  are  not
intended  to represent estimates  of the fair  value of oil  and gas properties.
Estimates of  fair value  should also  consider probable  reserves,  anticipated
future oil and gas prices, interest rates, changes in development and production
costs  and risks associated  with future production. Because  of these and other
considerations, any  estimate  of  fair  value  is  necessarily  subjective  and
imprecise.
 
<TABLE>
<CAPTION>
                                                                                                   THREE MONTHS
                                                                 YEARS ENDED DECEMBER 31,         ENDED MARCH 31,
                                                           -------------------------------------  ---------------
                                                              1993        1994          1995           1996
                                                           ----------  -----------  ------------  ---------------
                                                                               (IN THOUSANDS)
<S>                                                        <C>         <C>          <C>           <C>
Future cash flows........................................  $   83,510  $   122,098  $    350,653   $     396,919
Future costs:
  Production.............................................     (31,811)     (46,345)     (145,510)       (162,146)
  Development............................................      (4,486)      (7,157)      (16,806)        (17,975)
                                                           ----------  -----------  ------------  ---------------
Future net cash flows....................................      47,213       68,596       188,337         216,798
10% annual discount for estimated timing of cash flows...     (20,836)     (31,817)      (75,041)        (87,707)
                                                           ----------  -----------  ------------  ---------------
Standardized measure of discounted net cash flows........  $   26,377  $    36,779  $    113,296   $     129,091
                                                           ----------  -----------  ------------  ---------------
                                                           ----------  -----------  ------------  ---------------
</TABLE>
 
                                      F-20
<PAGE>
   
                            COSTILLA ENERGY, L.L.C.
                      (A TEXAS LIMITED LIABILITY COMPANY)
    
 
   
             NOTES TO CONSOLIDATED FINANCIAL STATEMENTS (CONTINUED)
    
        (THE INFORMATION AND AMOUNTS FOR INTERIM PERIODS ARE UNAUDITED.)
 
   
(14) SUPPLEMENTAL OIL AND GAS RESERVE INFORMATION (UNAUDITED) (CONTINUED)
    
 
    CHANGES IN STANDARDIZED MEASURE OF DISCOUNTED FUTURE NET CASH FLOWS FROM
PROVED RESERVES
 
<TABLE>
<CAPTION>
                                                                                                  THREE MONTHS
                                                                  YEARS ENDED DECEMBER 31,       ENDED MARCH 31,
                                                              ---------------------------------  ---------------
                                                                1993       1994        1995           1996
                                                              ---------  ---------  -----------  ---------------
                                                                                (IN THOUSANDS)
<S>                                                           <C>        <C>        <C>          <C>
Increase (decrease):
  Purchase of minerals-in-place.............................  $   3,732  $  15,231  $    77,343    $        --
  Extensions and discoveries and improved recovery, net of
   future production and development costs..................      2,707      4,072        9,799          6,002
  Accretion of discount.....................................      2,056      2,638        3,678          2,832
  Net change in sales prices, net of production costs.......       (209)       503       (3,422)         9,229
  Changes in estimated future development costs.............        (16)       940       (2,419)          (235)
  Revisions of quantity estimates...........................      1,203     (7,248)      (2,855)         4,839
  Sales, net of production costs............................     (2,543)    (5,286)     (11,338)        (5,174)
  Changes of production rates (timing) and other............     (1,114)      (448)       5,731         (1,698)
                                                              ---------  ---------  -----------  ---------------
    Net increase............................................      5,816     10,402       76,517         15,795
Standardized measure of discounted future net cash flows:
    Beginning of period.....................................     20,561     26,377       36,779        113,296
                                                              ---------  ---------  -----------  ---------------
    End of period...........................................  $  26,377  $  36,779  $   113,296    $   129,091
                                                              ---------  ---------  -----------  ---------------
                                                              ---------  ---------  -----------  ---------------
</TABLE>
 
    The  1995  future cash  flows shown  above  include amounts  attributable to
proved undeveloped  reserves requiring  approximately  $15.0 million  of  future
development costs. If these reserves are not developed, the standardized measure
of  discounted future net  cash flows for  1995 shown above  would be reduced by
approximately $22.4 million.
 
                                      F-21
<PAGE>
                          INDEPENDENT AUDITORS' REPORT
 
The Members
Costilla Energy, L.L.C.:
 
    We have audited the accompanying statements of revenues and direct operating
expenses of the 1995 Acquisition (see Note  1) for the years ended December  31,
1993  and 1994,  and the period  ended June  12, 1995. These  statements are the
responsibility of the Company's management. Our responsibility is to express  an
opinion on these statements based on our audits.
 
    We  conducted  our audits  in  accordance with  generally  accepted auditing
standards. Those standards require that we plan and perform the audit to  obtain
reasonable  assurance  about  whether  the  statements  of  revenues  and direct
operating  expenses  are  free  of  material  misstatement.  An  audit  includes
examining,  on a test basis, evidence  supporting the amounts and disclosures in
the financial  statements.  An  audit also  includes  assessing  the  accounting
principles  used  and  significant  estimates made  by  management,  as  well as
evaluating the  overall  statement  presentation. We  believe  that  our  audits
provide a reasonable basis for our opinion.
 
    The  accompanying statements of revenues  and direct operating expenses were
prepared for the  purpose of  complying with the  rules and  regulations of  the
Securities  and  Exchange Commission  (for inclusion  in  Forms S-1  of Costilla
Energy, Inc. as  described in  Note 1)  and are not  intended to  be a  complete
presentation of the 1995 Acquisition interests' revenue and expenses.
 
    In  our opinion,  the statements of  revenues and  direct operating expenses
referred to above  present fairly, in  all material respects,  the revenues  and
direct  operating expenses of the 1995  Acquisition for the years ended December
31, 1993  and 1994,  and the  period ended  June 12,  1995, in  conformity  with
generally accepted accounting principles.
 
                                          KPMG PEAT MARWICK LLP
 
Midland, Texas
July 4, 1996
 
                                      F-22
<PAGE>
                            COSTILLA ENERGY, L.L.C.
 
                                1995 ACQUISITION
 
              STATEMENTS OF REVENUES AND DIRECT OPERATING EXPENSES
                                 (IN THOUSANDS)
 
   
<TABLE>
<CAPTION>
                                                                                YEARS ENDED
                                                                                DECEMBER 31,
                                                                            --------------------   PERIOD ENDED
                                                                              1993       1994     JUNE 12, 1995
                                                                            ---------  ---------  --------------
<S>                                                                         <C>        <C>        <C>
Revenues:
  Oil and condensate......................................................  $  18,542  $  16,217    $    7,572
  Natural gas.............................................................     13,780     11,407         3,358
                                                                            ---------  ---------  --------------
                                                                               32,322     27,624        10,930
Direct operating expenses:
  Lease operating.........................................................     13,376     11,220         4,550
  Workovers and dry hole costs............................................        462        470           109
  Production taxes........................................................      2,070      2,023           923
                                                                            ---------  ---------  --------------
                                                                               15,908     13,713         5,582
                                                                            ---------  ---------  --------------
Revenues in excess of direct operating expenses...........................  $  16,414  $  13,911    $    5,348
                                                                            ---------  ---------  --------------
                                                                            ---------  ---------  --------------
</TABLE>
    
 
                See the accompanying notes to these statements.
 
                                      F-23
<PAGE>
                            COSTILLA ENERGY, L.L.C.
 
                                1995 ACQUISITION
 
       NOTES TO THE STATEMENTS OF REVENUES AND DIRECT OPERATING EXPENSES
 
(1) BASIS OF PRESENTATION
    On June 12, 1995, Costilla Energy, L.L.C. and Costilla Petroleum Corporation
(collectively,  the "Company") acquired  from Parker &  Parsley Development L.P.
and Parker & Parsley Producing  L.P. (collectively, "Parker & Parsley")  certain
oil   and  gas  properties   (the  "1995  Acquisition")   for  $46,621,371.  The
accompanying statements of revenues and  direct operating expenses for the  1995
Acquisition  do not include general and administrative expenses, interest income
or expense, a  provision for  depreciation, depletion and  amortization, or  any
provision  for income taxes since historical expenses of this nature incurred by
Parker & Parsley are not necessarily indicative  of the costs to be incurred  by
the Company.
 
    Historical  financial information reflecting  financial position, results of
operations, and cash flows  of the 1995 Acquisition,  are not presented  because
the  purchase price was assigned to the oil and gas property interests acquired.
Other assets acquired  and liabilities assumed  were not material.  Accordingly,
the  historical statements of revenues and direct operating expenses of the 1995
Acquisition are presented  in lieu  of the financial  statements required  under
Rule 3-05 of Securities and Exchange Commission Regulation S-X.
 
   
    Revenues  in the  accompanying statements  of revenues  and direct operating
expenses are recognized  on the sales  method. Under this  method, revenues  are
recognized  based on actual  volumes of oil  and gas sold  to purchasers. Direct
operating expenses are recognized on the accrual method.
    
 
(2) SUPPLEMENTARY FINANCIAL INFORMATION FOR OIL AND GAS PRODUCING ACTIVITIES
(UNAUDITED)
 
    ESTIMATED QUANTITIES OF PROVED OIL AND GAS RESERVES
 
    Reserve information presented  below for  the 1995 Acquisition  is based  on
Company prepared reserve estimates, using prices and costs in effect at December
31,  1993  and 1994,  and the  period ended  June 12,  1995. Changes  in reserve
estimates were derived  by adjusting  the period-end quantities  and values  for
actual production using historical prices and costs.
 
    Proved  reserves are estimated quantities of crude oil and natural gas which
geological and  engineering data  demonstrate with  reasonable certainty  to  be
recoverable  in future years  from known reservoirs  under existing economic and
operating conditions. Proved developed reserves are those which are expected  to
be  recovered  through  existing  wells with  existing  equipment  and operating
methods. Oil  and  gas  reserve  quantity  estimates  are  subject  to  numerous
uncertainties inherent in the estimation of quantities of proved reserves and in
the  projection  of future  rates of  production and  the timing  of development
expenditures. The accuracy  of such estimates  is a function  of the quality  of
available  data and of  engineering and geological  interpretation and judgment.
Results of subsequent drilling, testing  and production may cause either  upward
or  downward revision of previous estimates.  Further, the volumes considered to
be commercially  recoverable  fluctuate with  changes  in prices  and  operating
costs.  The Company emphasizes  that reserve estimates  are inherently imprecise
and that estimates of new discoveries are more imprecise than those of currently
producing oil  and  gas properties.  Accordingly,  these reserve  estimates  are
expected to change as additional information becomes available in the future.
 
                                      F-24
<PAGE>
                            COSTILLA ENERGY, L.L.C.
 
                                1995 ACQUISITION
 
 NOTES TO THE STATEMENTS OF REVENUES AND DIRECT OPERATING EXPENSES (CONTINUED)
 
(2) SUPPLEMENTARY FINANCIAL INFORMATION FOR OIL AND GAS PRODUCING ACTIVITIES
(UNAUDITED)
    (CONTINUED)
    Below  are  the  net  estimated quantities  of  proved  reserves  and proved
developed reserves for the 1995 Acquisition.
 
<TABLE>
<CAPTION>
                                                                     OIL (MBBLS)  GAS (MMCF)
                                                                     -----------  -----------
<S>                                                                  <C>          <C>
Proved reserves at December 31, 1992...............................       9,880       60,199
Production.........................................................      (1,204)      (6,914)
                                                                     -----------  -----------
Proved reserves at December 31, 1993...............................       8,676       53,285
Production.........................................................      (1,142)      (6,778)
                                                                     -----------  -----------
Proved reserves at December 31, 1994...............................       7,534       46,507
Production.........................................................        (479)      (2,405)
                                                                     -----------  -----------
Proved reserves at June 12, 1995...................................       7,055       44,102
                                                                     -----------  -----------
                                                                     -----------  -----------
Proved developed reserves at June 12, 1995.........................       6,707       38,151
                                                                     -----------  -----------
                                                                     -----------  -----------
</TABLE>
 
    STANDARDIZED MEASURE OF DISCOUNTED FUTURE NET CASH FLOWS OF PROVED OIL AND
GAS RESERVES
 
    The Company has estimated the standardized measure of discounted future  net
cash  flows  and changes  therein relating  to  proved oil  and gas  reserves in
accordance with the standards established by the Financial Accounting  Standards
Board  through its  Statement No.  69. The  estimates of  future cash  flows and
future production and development costs are based on period-end sales prices for
oil and  gas, estimated  future  production of  proved reserves,  and  estimated
future  production and  development costs of  proved reserves,  based on current
costs and economic  conditions. The  estimated future  net cash  flows are  then
discounted at a rate of 10%.
 
    Discounted  future net  cash flow estimates  like those shown  below are not
intended to  represent  estimates  of the  fair  market  value of  oil  and  gas
properties.  Estimates  of  fair  market  value  should  also  consider probable
reserves, anticipated  future oil  and gas  prices, interest  rates, changes  in
development  and production costs  and risks associated  with future production.
Because of these and other considerations, any estimate of fair market value  is
necessarily subjective and imprecise.
 
   
    The following are the Company's estimated standardized measure of discounted
future net cash flows from proved reserves attributable to the 1995 Acquisition:
    
 
   
<TABLE>
<CAPTION>
                                                                       DECEMBER 31,
                                                                 ------------------------
                                                                    1993         1994      JUNE 12, 1995
                                                                 -----------  -----------  -------------
                                                                             (IN THOUSANDS)
<S>                                                              <C>          <C>          <C>
Future:
  Cash inflows.................................................  $   222,698  $   188,828   $   191,758
  Production costs.............................................     (111,619)     (97,988)      (93,268)
  Development costs............................................       (4,797)      (4,797)       (4,797)
                                                                 -----------  -----------  -------------
    Net cash flows before income taxes.........................      106,282       86,043        93,693
10% annual discount for estimated timing of cash flows.........      (37,518)     (30,373)      (33,074)
                                                                 -----------  -----------  -------------
Standardized measure of discounted future net cash flows before
 income taxes..................................................  $    68,764  $    55,670   $    60,619
                                                                 -----------  -----------  -------------
                                                                 -----------  -----------  -------------
</TABLE>
    
 
                                      F-25
<PAGE>
                            COSTILLA ENERGY, L.L.C.
 
                                1995 ACQUISITION
 
 NOTES TO THE STATEMENTS OF REVENUES AND DIRECT OPERATING EXPENSES (CONTINUED)
 
(2) SUPPLEMENTARY FINANCIAL INFORMATION FOR OIL AND GAS PRODUCING ACTIVITIES
(UNAUDITED)
    (CONTINUED)
   
    The  following are  the sources  of changes  in the  standardized measure of
discounted net cash flows:
    
 
   
<TABLE>
<CAPTION>
                                                                YEARS ENDED DECEMBER
                                                                        31,
                                                               ----------------------  PERIOD ENDED
                                                                  1993        1994     JUNE 12, 1995
                                                               ----------  ----------  -------------
                                                                          (IN THOUSANDS)
<S>                                                            <C>         <C>         <C>
Standardized measure, beginning of period....................  $   96,022  $   68,764   $    55,670
Sales, net of production costs...............................     (16,414)    (13,911)       (5,348)
Net change in prices.........................................     (15,892)     (3,910)        8,032
Accretion of discount........................................       9,602       6,876         2,517
Other........................................................      (4,554)     (2,149)         (252)
                                                               ----------  ----------  -------------
Standardized measure, end of period..........................  $   68,764  $   55,670   $    60,619
                                                               ----------  ----------  -------------
                                                               ----------  ----------  -------------
</TABLE>
    
 
                                      F-26
<PAGE>
                          INDEPENDENT AUDITORS' REPORT
 
The Members
Costilla Energy, L.L.C.:
 
    We have audited the accompanying statements of revenues and direct operating
expenses  of the 1996 Acquisition (see Note  1) for the years ended December 31,
1993, 1994 and 1995.  These statements are the  responsibility of the  Company's
management.  Our responsibility  is to  express an  opinion on  these statements
based on our audits.
 
    We conducted  our  audits in  accordance  with generally  accepted  auditing
standards.  Those standards require that we plan and perform the audit to obtain
reasonable assurance  about  whether  the  statements  of  revenues  and  direct
operating  expenses  are  free  of  material  misstatement.  An  audit  includes
examining, on a test basis, evidence  supporting the amounts and disclosures  in
the  financial  statements.  An  audit also  includes  assessing  the accounting
principles used  and  significant  estimates  made by  management,  as  well  as
evaluating  the  overall  statement  presentation. We  believe  that  our audits
provide a reasonable basis for our opinion.
 
    The accompanying statements of revenues  and direct operating expenses  were
prepared  for the  purpose of  complying with the  rules and  regulations of the
Securities and  Exchange Commission  (for  inclusion in  Forms S-1  of  Costilla
Energy,  Inc. as  described in  Note 1) and  are not  intended to  be a complete
presentation of the 1996 Acquisition interests' revenues and expenses.
 
    In our opinion,  the statements  of revenues and  direct operating  expenses
referred  to above  present fairly, in  all material respects,  the revenues and
direct operating expenses of the 1996  Acquisition for the years ended  December
31,  1993,  1994  and 1995,  in  conformity with  generally  accepted accounting
principles.
 
                                          KPMG PEAT MARWICK LLP
 
Midland, Texas
July 4, 1996
 
                                      F-27
<PAGE>
                            COSTILLA ENERGY, L.L.C.
                                1996 ACQUISITION
              STATEMENTS OF REVENUES AND DIRECT OPERATING EXPENSES
 
                                 (IN THOUSANDS)
 
   
<TABLE>
<CAPTION>
                                                                      YEARS ENDED                  PERIODS
                                                                     DECEMBER 31,               ENDED JUNE 14,
                                                            -------------------------------  --------------------
                                                              1993       1994       1995       1995       1996
                                                            ---------  ---------  ---------  ---------  ---------
<S>                                                         <C>        <C>        <C>        <C>        <C>
                                                                                                 (UNAUDITED)
Revenues:
  Oil and condensate......................................  $  11,467  $  10,170  $  10,564  $   5,140  $   5,205
  Natural gas.............................................     11,294     10,105      8,645      3,763      3,434
  Gas plant...............................................         57         57        126         47         42
  Transportation..........................................         39        379        556        253        542
                                                            ---------  ---------  ---------  ---------  ---------
                                                               22,857     20,711     19,891      9,203      9,223
 
Direct operating expenses:
  Lease operating.........................................     10,977      9,053      9,232      3,965      4,020
  Workovers and dry hole costs............................        675        869      1,002        256        450
  Production taxes........................................      1,166      1,089        992        458        453
  Gas plant...............................................        131        350        598        393        269
  Transportation..........................................         10        394        587        268        222
                                                            ---------  ---------  ---------  ---------  ---------
                                                               12,959     11,755     12,411      5,340      5,414
                                                            ---------  ---------  ---------  ---------  ---------
Revenues in excess of direct operating expenses...........  $   9,898  $   8,956  $   7,480  $   3,863  $   3,809
                                                            ---------  ---------  ---------  ---------  ---------
                                                            ---------  ---------  ---------  ---------  ---------
</TABLE>
    
 
                See the accompanying notes to these statements.
 
                                      F-28
<PAGE>
                            COSTILLA ENERGY, L.L.C.
                                1996 ACQUISITION
       NOTES TO THE STATEMENTS OF REVENUES AND DIRECT OPERATING EXPENSES
 
(1) BASIS OF PRESENTATION
    On June 14, 1996, Costilla Energy, L.L.C. and Costilla Petroleum Corporation
(collectively, the "Company") acquired from  Parker & Parsley Development  L.P.,
Parker  &  Parsley  Producing  L.P.  and Parker  &  Parsley  Gas  Processing Co.
(collectively, "Parker &  Parsley") certain  oil and gas  properties (the  "1996
Acquisition")  for approximately  $42.5 million. The  accompanying statements of
revenues and direct operating expenses for  the 1996 Acquisition do not  include
general and administrative expenses, interest income or expense, a provision for
depreciation,  depletion  and amortization,  or any  provision for  income taxes
since historical expenses of  this nature incurred by  Parker & Parsley are  not
necessarily indicative of the costs to be incurred by the Company.
 
    Historical  financial information reflecting  financial position, results of
operations, and cash flows  of the 1996 Acquisition,  are not presented  because
the  purchase price was assigned to the oil and gas property interests acquired.
Other assets acquired  and liabilities assumed  were not material.  Accordingly,
the  historical statements of revenues and direct operating expenses of the 1996
Acquisition are presented  in lieu  of the financial  statements required  under
Rule 3-05 of Securities and Exchange Commission Regulation S-X.
 
   
    Revenues  in the  accompanying statements  of revenues  and direct operating
expenses are recognized  on the sales  method. Under this  method, revenues  are
recognized  based on actual  volumes of oil  and gas sold  to purchasers. Direct
operating expenses are recognized on the accrual method.
    
 
    INTERIM STATEMENTS OF REVENUES AND DIRECT OPERATING EXPENSES
 
   
    The interim financial information  for the periods ended  June 14, 1995  and
1996,  is  unaudited.  However,  in  the  opinion  of  management,  the  interim
statements of revenues and direct  operating expenses include all the  necessary
adjustments  to fairly present the  results of the interim  periods and all such
adjustments are of a normal recurring nature. The interim statements of revenues
and direct operating  expenses should be  read in conjunction  with the  audited
statements  of  revenues  and  direct operating  expenses  for  the  years ended
December 31, 1993, 1994 and 1995.
    
 
(2) SUPPLEMENTARY FINANCIAL INFORMATION FOR OIL AND GAS PRODUCING ACTIVITIES
(UNAUDITED)
 
    ESTIMATED QUANTITIES OF PROVED OIL AND GAS RESERVES
 
    Reserve information presented below  for the 1996  Acquisition, as of  March
31,  1996,  is  based  on reserve  estimates  prepared  by  Williamson Petroleum
Consultants, using prices and costs in  effect at that date. Changes in  reserve
estimates  were  derived  by adjusting  such  quantities and  values  for actual
production using historical prices and costs.
 
    Proved reserves are estimated quantities of crude oil and natural gas  which
geological  and  engineering data  demonstrate with  reasonable certainty  to be
recoverable in future years  from known reservoirs  under existing economic  and
operating  conditions. Proved developed reserves are those which are expected to
be recovered  through  existing  wells with  existing  equipment  and  operating
methods.  Oil  and  gas  reserve  quantity  estimates  are  subject  to numerous
uncertainties inherent in the estimation of quantities of proved reserves and in
the projection  of future  rates of  production and  the timing  of  development
expenditures.  The accuracy of  such estimates is  a function of  the quality of
available data and  of engineering and  geological interpretation and  judgment.
Results  of subsequent drilling, testing and  production may cause either upward
or downward revision of previous  estimates. Further, the volumes considered  to
be  commercially  recoverable fluctuate  with  changes in  prices  and operating
costs. The Company  emphasizes that reserve  estimates are inherently  imprecise
and that
 
                                      F-29
<PAGE>
                            COSTILLA ENERGY, L.L.C.
                                1996 ACQUISITION
 NOTES TO THE STATEMENTS OF REVENUES AND DIRECT OPERATING EXPENSES (CONTINUED)
 
(2) SUPPLEMENTARY FINANCIAL INFORMATION FOR OIL AND GAS PRODUCING ACTIVITIES
(UNAUDITED) (CONTINUED)
estimates  of  new  discoveries  are  more  imprecise  than  those  of currently
producing oil  and  gas properties.  Accordingly,  these reserve  estimates  are
expected to change as additional information becomes available in the future.
 
    Below  are  the  net  estimated quantities  of  proved  reserves  and proved
developed reserves for the 1996 Acquisition.
 
<TABLE>
<CAPTION>
                                                                                          OIL (MBBLS)  GAS (MMCF)
                                                                                          -----------  -----------
<S>                                                                                       <C>          <C>
Proved reserves at December 31, 1992....................................................       7,211       49,963
Production..............................................................................        (718)      (5,481)
                                                                                               -----   -----------
Proved reserves at December 31, 1993....................................................       6,493       44,482
Production..............................................................................        (685)      (5,217)
                                                                                               -----   -----------
Proved reserves at December 31, 1994....................................................       5,808       39,265
Production..............................................................................        (656)      (4,773)
                                                                                               -----   -----------
Proved reserves at December 31, 1995....................................................       5,152       34,492
Production..............................................................................        (154)        (991)
                                                                                               -----   -----------
Proved reserves at March 31, 1996.......................................................       4,998       33,501
                                                                                               -----   -----------
                                                                                               -----   -----------
Proved developed reserves at March 31, 1996.............................................       4,515       28,961
                                                                                               -----   -----------
                                                                                               -----   -----------
</TABLE>
 
STANDARDIZED MEASURE OF DISCOUNTED FUTURE NET CASH FLOWS OF PROVED OIL AND GAS
RESERVES
 
    The Company has estimated the standardized measure of discounted future  net
cash  flows  and changes  therein relating  to  proved oil  and gas  reserves in
accordance with the standards established by the Financial Accounting  Standards
Board  through its  Statement No.  69. The  estimates of  future cash  flows and
future production and development costs are  based on year-end sales prices  for
oil  and  gas, estimated  future production  of  proved reserves,  and estimated
future production and  development costs  of proved reserves,  based on  current
costs  and economic  conditions. The  estimated future  net cash  flows are then
discounted at a rate of 10%.
 
    Discounted future net  cash flow estimates  like those shown  below are  not
intended  to  represent  estimates of  the  fair  market value  of  oil  and gas
properties. Estimates  of  fair  market  value  should  also  consider  probable
reserves,  anticipated future  oil and  gas prices,  interest rates,  changes in
development and production  costs and risks  associated with future  production.
Because  of these and other considerations, any estimate of fair market value is
necessarily subjective and imprecise.
 
                                      F-30
<PAGE>
                            COSTILLA ENERGY, L.L.C.
                                1996 ACQUISITION
 NOTES TO THE STATEMENTS OF REVENUES AND DIRECT OPERATING EXPENSES (CONTINUED)
 
(2) SUPPLEMENTARY FINANCIAL INFORMATION FOR OIL AND GAS PRODUCING ACTIVITIES
(UNAUDITED) (CONTINUED)
   
    The following are the Company's estimated standardized measure of discounted
future net cash flows from proved reserves attributable to the 1996 Acquisition:
    
 
   
<TABLE>
<CAPTION>
                                                                           DECEMBER 31,
                                                              ---------------------------------------   MARCH 31,
                                                                  1993          1994         1995         1996
                                                              ------------  ------------  -----------  -----------
                                                                          (IN THOUSANDS)
<S>                                                           <C>           <C>           <C>          <C>
Future:
  Cash inflows..............................................  $    181,010  $    156,222  $   165,862  $   175,507
  Production costs..........................................      (116,115)     (105,104)     (93,878)     (91,202)
  Development costs.........................................        (4,101)       (4,101)      (4,101)      (4,101)
                                                              ------------  ------------  -----------  -----------
    Net cash flows before income taxes......................        60,794        47,017       67,883       80,204
10% annual discount for estimated timing of cash flows......       (22,564)      (17,451)     (25,195)     (29,768)
                                                              ------------  ------------  -----------  -----------
Standardized measure of discounted future net cash flows
 before income taxes........................................  $     38,230  $     29,566  $    42,688  $    50,436
                                                              ------------  ------------  -----------  -----------
                                                              ------------  ------------  -----------  -----------
</TABLE>
    
 
   
    The following are  the sources  of changes  in the  standardized measure  of
discounted net cash flows:
    
 
   
<TABLE>
<CAPTION>
                                                                                                   THREE MONTH
                                                                     YEARS ENDED DECEMBER 31,      PERIOD ENDED
                                                                  -------------------------------   MARCH 31,
                                                                    1993       1994       1995         1996
                                                                  ---------  ---------  ---------  ------------
                                                                          (IN THOUSANDS)
<S>                                                               <C>        <C>        <C>        <C>
Standardized measure, beginning of period.......................  $  56,372  $  38,230  $  29,566   $   42,688
Sales, net of production costs..................................     (9,943)    (9,264)    (7,983)      (2,090)
Net change in prices............................................    (11,890)    (2,838)    18,141        9,277
Accretion of discount...........................................      5,637      3,823      2,957        1,067
Other...........................................................     (1,946)      (385)         7         (506)
                                                                  ---------  ---------  ---------  ------------
Standardized measure, end of period.............................  $  38,230  $  29,566  $  42,688   $   50,436
                                                                  ---------  ---------  ---------  ------------
                                                                  ---------  ---------  ---------  ------------
</TABLE>
    
 
                                      F-31
<PAGE>
                                                                      APPENDIX A
 
                                 July 23, 1996
 
Costilla Energy, Inc.
400 West Illinois, Suite 1000
Midland, Texas 79701
 
Attention  Mr. Michael J. Grella
 
Gentlemen:
 
Subject:    Summary  Letter  (for Inclusion  in a  Prospectus Included  in a
            Registration Statement for  Costilla Energy, Inc.  on Form  S-1)
            Combining   Specific   Data   from   Two   Williamson  Petroleum
            Consultants, Inc. Evaluations (1)  to the Interests of  Costilla
            Petroleum  Corporation  in  Various Properties  and  (2)  to the
            Interests of Parker  & Parsley  Petroleum USA,  Inc. in  Various
            Properties Included in Their First Quarter 1996 Sales Package
            Effective April 1, 1996
            Williamson Project 6.8393
 
    In  accordance  with your  request,  Williamson Petroleum  Consultants, Inc.
(Williamson) has prepared  a summary letter  for inclusion in  a prospectus  for
Costilla  Energy, Inc. (Costilla). The filing of this Prospectus gives effect to
the conversion of Costilla Energy, L.L.C. to Costilla Energy, Inc. This  summary
letter  includes specific  data from two  evaluations the subjects  of which are
described in  Item I.  All values  and  discussion of  proved reserves  and  net
revenues,  data  utilized, assumptions,  and qualifications  are taken  from and
include by reference data from these two evaluations.
 
    Interests in this summary letter represent the April 1, 1996 effective  date
consolidation of the ownership interests of Costilla and the ownership interests
of  Parker & Parsley in various properties  included in their first quarter 1996
sales package  which Costilla  acquired on  June  14, 1996  but which  was  made
effective  as  of  January  1,  1996. The  Costilla  interests  include  all the
interests of  Costilla  Energy, L.L.C.  and  all its  wholly-owned  subsidiaries
including Costilla Petroleum Corporation.
 
I.  THE TWO SUBJECT EVALUATIONS
 
    This  summary  letter  combines  certain proved  oil  and  gas  reserves and
revenues from the following two Williamson evaluations:
 
    (1) Evaluation  of  Oil  and  Gas Reserves  to  the  Interests  of  Costilla
       Petroleum  Corporation in  Various Properties,  Effective April  1, 1996,
       Utilizing Nonescalated Economics,  for Disclosure to  the Securities  and
       Exchange Commission, Williamson Project 6.8393, transmitted July 18, 1996
       (the Costilla report)
 
    (2)  Evaluation of Oil and Gas Reserves to the Interests of Parker & Parsley
       Petroleum USA, Inc. in Various Properties Included in Their First Quarter
       1996 Sales  Package,  Effective  April 1,  1996,  Utilizing  Nonescalated
       Economics,  for  Disclosure to  the  Securities and  Exchange Commission,
       Williamson Project  6.8393, transmitted  July 18,  1996 (the  Acquisition
       report)
 
II.  ESTIMATED SEC RESERVES AND FUTURE NET REVENUES
 
    Projections  of  the  reserves  that are  attributable  to  the consolidated
interests in this summary letter were based on economic parameters and operating
conditions considered applicable  as of April  1, 1996 and  are pursuant to  the
requirements of the Securities and Exchange Commission (SEC).
 
    In  accordance with  instructions from  Costilla, Williamson  utilized lease
operating expenses for the Costilla-operated  properties in the Costilla  report
that excluded COPAS overhead and internal
 
                                      A-1
<PAGE>
Costilla Energy, Inc.
Mr. Michael J. Grella
July 23, 1996
Page 2
indirect  overhead  which are  billed to  outside  working interest  owners. The
exclusion of these costs for the operated properties results in the  calculation
of  a lower  economic limit  and causes  the economic  lifetime to  be extended.
Williamson has  not  quantified the  incremental  reserves resulting  from  this
procedure. COPAS overhead was excluded from the lease operating expenses for the
Parker & Parsley-operated properties in the Acquisition report.
 
    The present values of the estimated future net revenues from proved reserves
were  calculated  using a  discount  rate of  10.00  percent per  year  and were
computed in accordance  with the  financial reporting requirements  of the  SEC.
Following  is a summary of the results of the two evaluations effective April 1,
1996:
 
<TABLE>
<CAPTION>
                                                 PROVED           PROVED
                                               DEVELOPED         DEVELOPED           PROVED           TOTAL
                                               PRODUCING       NONPRODUCING       UNDEVELOPED         PROVED
                                             --------------  -----------------  ----------------  --------------
<S>                                          <C>             <C>                <C>               <C>
Net Reserves to the Evaluated Interests:
  Oil/Condensate, BBL......................      13,122,088          429,450          2,924,589       16,476,127
  Gas, MCF.................................      76,439,217        7,929,591         28,551,497      112,920,305
Future Net Revenue, $:
  Undiscounted.............................     212,071,507       18,097,949         66,832,632      297,002,088
  Discounted Per Annum at 10.00 Percent....     135,185,097        9,530,285         34,811,523      179,526,905
</TABLE>
 
- ------------------------
Note: The values presented in this table are taken from evaluations described in
      Item I and include by reference all data, qualifications, and  assumptions
      from  these  evaluations. Realization  of  these values  is  contingent on
      achieving successful results from the various schedules and assumptions in
      these evaluations.  The available  engineering data  and the  completeness
      and/or  quality of data utilized in evaluating the properties are detailed
      in the specific evaluation. Review of any additionally available data  may
      necessitate  revision to these interpretations  and assumptions and impact
      these values.
 
III.  DEFINITIONS OF SEC RESERVES (1)
 
    The estimated  reserves presented  in  this summary  letter are  net  proved
reserves,  including proved developed  producing, proved developed nonproducing,
and proved  undeveloped  reserves, and  were  computed in  accordance  with  the
financial  reporting requirements of the SEC. In preparing these evaluations, no
attempt has been made to quantify the element of uncertainty associated with any
category. Reserves were assigned to each category as warranted. The  definitions
of  oil and gas reserves pursuant to the requirements of the Securities Exchange
Act are:
 
PROVED RESERVES (2)
 
    Proved reserves are the estimated quantities of crude oil, natural gas,  and
natural  gas  liquids which  geological  and engineering  data  demonstrate with
reasonable certainty to  be recoverable  in future years  from known  reservoirs
under the economic criteria employed and existing operating
 
- ------------------------
(1)  For  evaluations prepared  for disclosure  to  the Securities  and Exchange
    Commission, see SEC ACCOUNTING RULES. Commerce Clearing House, Inc.  October
    1981, Paragraph 290, Regulation 210.4-10, p. 329.
 
(2) Any variations to these definitions will be clearly stated in the report.
 
                                      A-2
<PAGE>
Costilla Energy, Inc.
Mr. Michael J. Grella
July 23, 1996
Page 3
conditions,  i.e., prices and costs as of  the date the estimate is made. Prices
and  costs  include  consideration  of  changes  provided  only  by  contractual
arrangements but not on escalations based upon an estimate of future conditions.
 
A.   Reservoirs are considered proved  if economic producibility is supported by
    either actual  production  or  conclusive  formation test.  The  area  of  a
    reservoir considered proved includes:
 
    1.    that portion  delineated  by drilling  and  defined by  gas-oil and/or
       oil-water contacts, if any; and
 
    2.  the  immediately adjoining portions  not yet drilled,  but which can  be
       reasonably  judged as economically  productive on the  basis of available
       geological and engineering data. In  the absence of information on  fluid
       contacts, the lowest known structural occurrence of hydrocarbons controls
       the lower proved limit of the reservoir.
 
B.   Reserves which can be produced economically through application of improved
    recovery techniques (such as fluid  injection) are included in the  "proved"
    classification  when successful testing by a pilot project, or the operation
    of  an  installed  program  in  the  reservoir,  provides  support  for  the
    engineering analysis on which the project or program was based.
 
C.  Estimates of proved reserves do not include the following:
 
    1.   oil that may  become available from known  reservoirs but is classified
       separately as "indicated additional reserves;"
 
    2.  crude oil, natural gas, and  natural gas liquids, the recovery of  which
       is  subject to  reasonable doubt  because of  uncertainty as  to geology,
       reservoir characteristics, or economic factors;
 
    3.  crude  oil, natural  gas, and  natural gas  liquids, that  may occur  in
       undrilled prospects; and
 
    4.   crude oil, natural gas, and  natural gas liquids, that may be recovered
       from oil shales, coal (3), gilsonite and other such sources.
 
PROVED DEVELOPED RESERVES (4)
 
    Proved developed reserves are reserves that can be expected to be  recovered
through existing wells with existing equipment and operating methods. Additional
oil  and gas expected to be obtained  through the application of fluid injection
or other improved recovery techniques  for supplementing the natural forces  and
mechanisms of primary recovery should be included as "proved developed reserves"
only  after testing by  a pilot project  or after the  operation of an installed
program has confirmed through production  response that increased recovery  will
be achieved.
 
PROVED UNDEVELOPED RESERVES
 
    Proved  undeveloped reserves are reserves that  are expected to be recovered
from new wells on undrilled acreage,  or from existing wells where a  relatively
major  expenditure is required  for recompletion. Reserves  on undrilled acreage
shall   be   limited   to    those   drilling   units   offsetting    productive
 
- ------------------------
(3) According to Staff Accounting Bulletin 85, excluding certain coalbed methane
    gas.
 
(4)  Williamson Petroleum Consultants, Inc.  separates proved developed reserves
    into proved developed producing and proved developed nonproducing  reserves.
    This  is  to identify  proved developed  producing reserves  as those  to be
    recovered from  actively  producing  wells;  proved  developed  nonproducing
    reserves  as those  to be  recovered from  wells or  intervals within wells,
    which  are  completed  but  shut   in  waiting  on  equipment  or   pipeline
    connections,  or wells where a relatively  minor expenditure is required for
    recompletion to another zone.
 
                                      A-3
<PAGE>
Costilla Energy, Inc.
Mr. Michael J. Grella
July 23, 1996
Page 4
units that are reasonably  certain of production  when drilled. Proved  reserves
for  other undrilled units can be claimed only where it can be demonstrated with
certainty that there is  continuity of production  from the existing  productive
formation.  Under  no  circumstances  should  estimates  for  proved undeveloped
reserves be  attributable to  any  acreage for  which  an application  of  fluid
injection  or  other improved  recovery technique  is contemplated,  unless such
techniques have been proved  effective by actual  tests in the  area and in  the
same reservoir.
 
IV.  DISCUSSION OF SEC RESERVES
 
A.  THE COSTILLA REPORT
 
    A  total of 1,014  properties in 294  fields were evaluated  in the Costilla
    report. Nineteen individual properties had  values greater than 1.0  percent
    of the total future net revenue discounted at 10.00 percent per annum (DFNR)
    and  in aggregate represent 34.5 percent of the DFNR in the Costilla report.
    The most valued property, the T.B. Pruett  Gas Unit No. 3, Soda Lake  field,
    Ward  County, Texas, had a  value equal to 4.5 percent  of the total DFNR in
    the Costilla report. The top  eight major-value fields are Talbot  (Canyon),
    Howard  County, Texas; Spraberry (Trend Area), Various Counties, Texas; Soda
    Lake (Fusselman), Ward  County, Texas;  South Buffalo  Ridge, Crane  County,
    Texas;  Wattenberg,  Weld County,  Colorado;  East Goldsmith,  Ector County,
    Texas; Raymond,  Sheridan County,  Montana; and  South West  Speaks,  Lavaca
    County,  Texas. These fields contain ten of  the 19 top value properties and
    represent, in aggregate,  41.0 percent  of the  total DFNR  in the  Costilla
    report. The remaining 286 fields represent 59.0 percent with no field having
    more  than 2.9 percent of  the DFNR in the  Costilla report. A more detailed
    property review is included in the Costilla report.
 
    Area oil prices were provided by Costilla  to be used at the effective  date
    with  the written assurance that the use  of these area prices is reasonable
    on an aggregate basis  and would not materially  affect the income from  any
    major-value  property. These  area prices  were calculated  by adjusting the
    West Texas Intermediate oil April 1, 1996 posted price of $20.75 per barrel.
    The oil  price adjustments  for  each area  are the  calculated  differences
    between  the actual price received during 1995 and the posted price for West
    Texas Intermediate oil during  that same period.  After the effective  date,
    prices  were held constant  for the life  of the properties.  No attempt has
    been made to account for oil  price fluctuations which have occurred in  the
    market subsequent to the effective date of this report.
 
    Gas prices were provided by Costilla to be used at the effective date. These
    prices  were based on the April 1996 spot price of $1.75 per million British
    thermal units  (MMBTU) at  the Waha,  Texas receipt  point. This  price  was
    adjusted  with  an  area  price  adjustment  which  was  calculated  as  the
    difference between the actual price received during 1995 and the stop price.
    The resultant price was further adjusted for the BTU content of the gas  for
    each  well. If the BTU  content was unknown, it was  assumed to be one MMBTU
    per MCF of gas. After the effective date, prices were held constant for  the
    life  of the properties unless Costilla indicated that changes were provided
    for by contract. All gas prices were applied to projected wellhead volumes.
 
    It should  be  emphasized  that with  the  current  economic  uncertainties,
    fluctuation in market conditions could significantly change the economics of
    the properties included in this report.
 
    Operating expenses were provided by Costilla and represented, when possible,
    the  latest available 12-month  average of all  recurring expenses excluding
    COPAS and internal indirect overhead costs which are billable to the working
    interest owners.  These expenses  included,  but were  not limited  to,  all
    direct  operating expenses, field  overhead costs, and  any ad valorem taxes
    not
 
                                      A-4
<PAGE>
Costilla Energy, Inc.
Mr. Michael J. Grella
July 23, 1996
Page 5
    deducted separately. Expenses  for workovers, well  stimulations, and  other
    maintenance were not included in the operating expenses unless such work was
    expected   on  a  recurring  basis.  Judgments  for  the  exclusion  of  the
    nonrecurring expenses were made by Costilla. In accordance with instructions
    from Costilla, Williamson has excluded COPAS overhead and internal  indirect
    overhead  which are billed  to the outside working  interest owners from the
    operating expenses for Costilla-operated properties. The exclusion of  these
    costs for operated properties results in the calculation of a lower economic
    limit  and causes the  economic lifetime to be  extended. Williamson has not
    calculated the reserves that have been added as a result of this  procedure.
    For  new and  developing properties  where data  were unavailable, operating
    expenses were estimated by Costilla. Operating costs were held constant  for
    the life of the properties.
 
    State  production  taxes  have  been  deducted  at  the  published  rates as
    appropriate. For  operated  properties,  average  county  ad  valorem  taxes
    provided  by Costilla were  deducted for those  properties located in states
    for which the  data were  available. Any  ad valorem  taxes for  nonoperated
    properties  or for properties in other states were assumed to be included in
    the operating expenses.
 
    All capital  costs for  drilling and  completion of  wells and  nonrecurring
    workover  or operating costs  have been deducted  as applicable. These costs
    were provided  by Costilla.  No adjustments  were made  to account  for  the
    potential effect of inflation on these costs.
 
    Neither salvage values nor abandonment costs were provided by Costilla to be
    included in this evaluation.
 
B.  THE ACQUISITION REPORT
 
    A  total of 1,091 properties in 135 fields were evaluated in the Acquisition
    report. Eighteen individual properties had  values greater than 1.0  percent
    of the total DFNR and in aggregate represent 35.5 percent of the DFNR in the
    Acquisition  report.  The most  valued  property, the  H.W.  Glasscock Unit,
    Howard-Glasscock field, Glasscock  County, Texas, has  a projected value  of
    5.7  percent of  the total  DFNR in  the Acquisition  report. The  top eight
    major-value fields  are  World,  Crockett  County,  Texas;  Dimmitt,  Loving
    County,   Texas;  Panna  Maria,  Karnes  County,  Texas;  Giddings,  Various
    Counties, Texas; Caldwell, Burleson  County, Texas; Coletto Creek,  Victoria
    County,  Texas;  Sawyer, Sutton  County,  Texas; and  Jameson,  Coke County,
    Texas. These fields contain 11 of the 18 top value properties and represent,
    in aggregate, 51.9 percent of the total DFNR in the Acquisition report.  The
    remaining  fields represent 48.1 percent with  no field having more than 2.9
    percent of the  DFNR in  the Acquisition  report. A  more detailed  property
    review is included in the Acquisition report.
 
    Area oil prices were provided by Costilla and Parker & Parsley to be used at
    the  effective date with  the written assurance  that the use  of these area
    prices is reasonable on an aggregate  basis and would not materially  affect
    the  income from any major-value property. These area prices were calculated
    by adjusting the West Texas Intermediate  oil April 1, 1996 posted price  of
    $20.75  per  barrel. The  oil price  adjustments as  calculated by  Parker &
    Parsley for  each area  are the  calculated differences  between the  actual
    price  received during 1995 and the posted price for West Texas Intermediate
    oil during that  same period.  After the  effective date,  prices were  held
    constant for the life of the properties. No attempt has been made to account
    for  oil price fluctuations which have  occurred in the market subsequent to
    the effective date of this report.
 
    Gas prices were provided by Costilla and Parker & Parsley to be used at  the
    effective  date. These  prices were  based on the  April 1996  spot price of
    $1.75 per million British thermal units
 
                                      A-5
<PAGE>
Costilla Energy, Inc.
Mr. Michael J. Grella
July 23, 1996
Page 6
    (MMBTU) at the Waha,  Texas receipt point. This  price was adjusted with  an
    area  price adjustment  which was calculated  as the  difference between the
    actual price received during  1995 and the stop  price. The resultant  price
    was  further adjusted for the  BTU content of the gas  for each well. If the
    BTU content was  unknown, it was  assumed to be  one MMBTU per  MCF of  gas.
    After  the effective  date, prices  were held constant  for the  life of the
    properties unless  Costilla  indicated that  changes  were provided  for  by
    contract. All gas prices were applied to projected wellhead volumes.
 
    It  should  be  emphasized  that with  the  current  economic uncertainties,
    fluctuation in market conditions could significantly change the economics of
    the properties included in this report.
 
    Operating expenses  were  provided by  Costilla  and Parker  &  Parsley  and
    represented,  when possible,  the latest  available 12-month  average of all
    recurring expenses  excluding COPAS  and  internal indirect  overhead  costs
    which  are billable to the working interest owners. These expenses included,
    but were  not limited  to,  all direct  operating expenses,  field  overhead
    costs,  and  any  ad valorem  taxes  not deducted  separately.  Expenses for
    workovers, well stimulations, and other maintenance were not included in the
    operating expenses  unless such  work  was expected  on a  recurring  basis.
    Judgments  for  the  exclusion of  the  nonrecurring expenses  were  made by
    Costilla or Parker & Parsley. In accordance with instructions from Costilla,
    Williamson has  excluded  COPAS overhead  which  is billed  to  the  outside
    working   interest  owners  from   the  operating  expenses   for  Parker  &
    Parsley-operated properties.  The  exclusion  of these  costs  for  operated
    properties  results in the calculation of  a lower economic limit and causes
    the economic  lifetime to  be extended.  Williamson has  not calculated  the
    reserves  that have been  added as a  result of this  procedure. For new and
    developing properties where data  were unavailable, operating expenses  were
    estimated  by  Costilla  or  Parker &  Parsley.  Operating  costs  were held
    constant for the life of the properties.
 
    State production  taxes  have  been  deducted  at  the  published  rates  as
    appropriate.  For  operated  properties,  average  county  ad  valorem taxes
    provided by Costilla were  deducted for those  properties located in  states
    for  which the  data were  available. Any  ad valorem  taxes for nonoperated
    properties or for properties in other states were assumed to be included  in
    the operating expenses.
 
    All  capital costs  for drilling  and completion  of wells  and nonrecurring
    workover or operating costs  have been deducted  as applicable. These  costs
    were  provided by Costilla or Parker &  Parsley. No adjustments were made to
    account for the potential effect of inflation on these costs.
 
    Neither salvage values nor abandonment costs were provided by Costilla to be
    included in this evaluation.
 
V.  GENERAL EVALUATION CONSIDERATIONS PERTAINING TO THE COSTILLA AND ACQUISITION
    REPORTS
 
    The individual projections prepared to  produce this summary letter  include
data that describe the production forecasts and associated evaluation parameters
such  as interests, taxes, product prices, operating costs, investments, salvage
values, abandonment costs, and net profit interests, as applicable.
 
    Net income to the evaluated interests  is the future net revenue payable  to
others,  taxes,  operating  expenses, investments,  salvage  values, abandonment
costs, and net profit interests, as applicable. The future net revenue is before
federal income tax and  excludes consideration of  any encumbrances against  the
properties if such exist.
 
                                      A-6
<PAGE>
Costilla Energy, Inc.
Mr. Michael J. Grella
July 23, 1996
Page 7
 
    No  opinion is expressed  by Williamson as  to the fair  market value of the
evaluated properties.
 
    The future  net revenues  presented in  this summary  letter were  based  on
projections  of  oil  and gas  production.  It  was assumed  there  would  be no
significant delay between the date of oil and gas production and the receipt  of
the associated revenue for this production.
 
    This  summary  letter  includes  only those  costs  and  revenues  which are
considered by  Costilla to  be directly  attributable to  individual leases  and
areas.  There  could  exist  other  revenues,  overhead  costs,  or  other costs
associated with Costilla  which are not  included in this  summary letter.  Such
additional costs and revenues are outside the scope of this summary letter. This
summary  letter is not a financial statement for Costilla and should not be used
as the sole basis for any transaction concerning Costilla, Parker & Parsley,  or
the evaluated properties.
 
    The  reserves projections in this summary letter are based on the use of the
available data and accepted industry engineering methods. Future changes in  any
operational   or  economic  parameters  or  production  characteristics  of  the
evaluated properties  could  increase  or decrease  their  reserves.  Unforeseen
changes  in market demand or allowables set by various regulatory agencies could
also cause actual production  rates to vary from  those projected. The dates  of
first production for nonproducing properties were based on estimates by Costilla
or  Williamson and  the actual dates  may vary from  those estimated. Williamson
reserves the right to alter any  of the reserves projections and the  associated
economics  included in  this summary  letter in  any future  evaluation based on
additional data that may be acquired.
 
    All data utilized in the preparation of this summary letter with respect  to
interests, reversionary status, oil and gas prices, gas categories, gas contract
terms,  operating expenses, investments, salvage  values, abandonment costs, net
profit  interests,  well  information  and  current  operating  conditions,   as
applicable, were provided by Costilla, Parker & Parsley, and the operators. Data
obtained  after the effective date of the  report but prior to the completion of
the report were used only if such  data were applied consistently. If such  data
were  used, the reserves category assignments reflect the status of the wells as
of the effective date. In the Costilla report, daily production data after April
1, 1996 were utilized  for new wells  in the South  Buffalo Ridge, Concho  Bluff
(Queen),  East  Goldsmith (Queen),  King  Mountain (Penn),  and  Talbot (Canyon)
fields to  assist in  determining  initial producing  and decline  rates.  Daily
production  since the effective date was also used  for the Pyote Gas Unit 5 No.
1A, Block 16  (Devonian) field, Ward  County, Texas to  establish the  producing
rate  after the well was affected by gas  plant problems and for the State 16-05
well in the  Raymond field, Sheridan  County, Montana to  establish the  initial
rate of production subsequent to the installation of a downhole pump. Production
data  generally through December  1995 or January 1996  provided by Costilla for
the properties in  the Costilla  report and  through November  or December  1995
provided  by Parker & Parsley for the  properties in the Acquisition report were
utilized. All data  have been  reviewed for reasonableness  and, unless  obvious
errors  were detected,  have been accepted  as correct. It  should be emphasized
that revisions to  the projections of  reserves and economics  included in  this
summary  letter may be required if the provided data are revised for any reason.
No inspection of the properties was made  as this was not considered within  the
scope  of  these  projects.  No  investigation  was  made  of  any environmental
liabilities that  might apply  to the  evaluated properties,  and no  costs  are
included for any possible related expenses.
 
    Unless  specifically  identified  and  documented by  Costilla  or  Parker &
Parsley as having curtailment problems, gas production trends have been  assumed
to  be a function of well productivity  and not of market conditions. The effect
of "take or pay" clauses in gas contracts was not considered.
 
                                      A-7
<PAGE>
Costilla Energy, Inc.
Mr. Michael J. Grella
July 23, 1996
Page 8
 
    Oil reserves  are expressed  in  United States  (U.S.)  barrels of  42  U.S.
gallons.  Gas  volumes are  expressed in  thousands  of cubic  feet (MCF)  at 60
degrees Fahrenheit and at the legal pressure base that prevails in the state  in
which the reserves are located. No adjustment of the individual gas volumes to a
common pressure base has been made.
 
    Costilla  represented  to  Williamson  that it  has,  or  can  generate, the
financial and operational capabilities to accomplish those projects evaluated by
Williamson which require capital expenditures.
 
    The estimates of reserves contained  in this summary letter were  determined
by  accepted industry methods and in accordance  with the definitions of oil and
gas reserves set forth  above. Methods utilized in  this summary letter  include
extrapolation  of historical production trends, material balance determinations,
analogy to similar properties, and volumetric calculations.
 
    Where sufficient production history and other data were available,  reserves
for   producing  properties  were  determined  by  extrapolation  of  historical
production trends or through the use of material balance determinations. Analogy
to similar  properties or  volumetric calculations  were used  for  nonproducing
properties  and those  producing properties  which lacked  sufficient production
history and other  data to  yield a  definitive estimate  of reserves.  Reserves
projections  based on analogy are subject to change due to subsequent changes in
the analogous properties or subsequent production from the evaluated properties.
Volumetric calculations are often  based upon limited  log and/or core  analysis
data and incomplete reservoir fluid and formation rock data. Since these limited
data  must frequently be extrapolated over  an assumed drainage area, subsequent
production performance trends  or material  balance calculations  may cause  the
need for significant revisions to the estimates of reserves.
 
    It  should  be  emphasized  that with  the  current  economic uncertainties,
fluctuation in market  conditions could  significantly change  the economics  in
this summary letter.
 
VII.  DECLARATION OF INDEPENDENT STATUS AND CONSENT
 
    We  understand  that our  estimates  are to  be  included in  a Registration
Statement on Form S-1 (the Registration Statement) to be filed with the SEC  and
in  the  Prospectus as  included in  such Registration  Statement which  will be
registered under the Securities Act of 1933, as amended.
 
    Williamson is an independent consulting firm and does not own any  interests
in the oil and gas properties covered by this summary letter. Roy C. Williamson,
Jr.,  Chief Executive Officer, owns a 2.5  percent working interest in six wells
in the Outlook  field, Sheridan  County, Montana, which  have a  total value  of
$138,912  to  the interests  of Costilla.  No employee,  officer or  director of
Williamson is an employee, officer or director of Costilla or Parker &  Parsley.
Neither  the  employment  of  nor the  compensation  received  by  Williamson is
contingent upon the  values assigned to  the oil and  gas properties covered  by
this summary letter.
 
    We  consent  to the  inclusion of  this summary  letter in  the Registration
Statement, the inclusion in  the Registration Statement  of data extracted  from
this  summary  letter and  to  all references  to  our firm  in  the Prospectus,
including any references to our firm as Experts.
 
                                    Yours very truly,
 
                                    WILLIAMSON PETROLEUM CONSULTANTS, INC.
 
                                      A-8
<PAGE>
- --------------------------------------------------------------------------------
- --------------------------------------------------------------------------------
 
    NO  DEALER, SALESMAN  OR ANY  OTHER PERSON HAS  BEEN AUTHORIZED  TO GIVE ANY
INFORMATION OR TO MAKE  ANY REPRESENTATIONS OTHER THAN  THOSE CONTAINED IN  THIS
PROSPECTUS  IN CONNECTION WITH THE OFFERING  COVERED BY THIS PROSPECTUS, AND, IF
GIVEN OR MADE, SUCH  INFORMATION OR REPRESENTATIONS MUST  NOT BE RELIED UPON  AS
HAVING  BEEN AUTHORIZED BY THE COMPANY OR THE UNDERWRITERS. THIS PROSPECTUS DOES
NOT CONSTITUTE AN  OFFER TO  SELL OR  THE SOLICITATION OF  AN OFFER  TO BUY  THE
SECURITIES  IN ANY JURISDICTION WHERE, OR ANY  PERSON TO WHOM, IT IS UNLAWFUL TO
MAKE SUCH OFFER OR SOLICITATION. NEITHER THE DELIVERY OF THIS PROSPECTUS NOR ANY
SALE MADE HEREUNDER SHALL, UNDER  ANY CIRCUMSTANCES, CREATE AN IMPLICATION  THAT
THERE  HAS NOT BEEN A CHANGE IN THE FACTS SET FORTH IN THIS PROSPECTUS OR IN THE
AFFAIRS OF THE COMPANY SINCE THE DATE HEREOF.
 
   
    UNTIL                  , 1996,  ALL DEALERS  EFFECTING TRANSACTIONS  IN  THE
REGISTERED SECURITIES, WHETHER OR NOT PARTICIPATING IN THIS DISTRIBUTION, MAY BE
REQUIRED  TO DELIVER  A PROSPECTUS.  THIS IS  IN ADDITION  TO THE  OBLIGATION OF
DEALERS TO DELIVER
    
   
A PROSPECTUS WHEN ACTING AS UNDERWRITERS AND
    
   
WITH RESPECT TO THEIR UNSOLD ALLOTMENTS OR SUBSCRIPTIONS.
    
                            ------------------------
 
                               TABLE OF CONTENTS
 
   
<TABLE>
<CAPTION>
                                                    PAGE
                                                    -----
<S>                                              <C>
Prospectus Summary.............................           3
Risk Factors...................................          10
The Company....................................          16
Common Stock Offering..........................          16
Use of Proceeds................................          17
Capitalization.................................          18
Pro Forma Condensed Financial Statements.......          19
Selected Financial Information.................          27
Management's Discussion and Analysis of
 Financial Condition and Results of
 Operations....................................          28
Business and Properties........................          34
Management.....................................          46
Security Ownership of Certain Beneficial Owners
 and Management................................          49
Executive Compensation and Other Information...          50
Certain Transactions...........................          53
Description of Notes...........................          55
Description of Other Indebtedness..............          82
Description of Capital Stock...................          82
Underwriting...................................          84
Legal Matters..................................          85
Experts........................................          85
Available Information..........................          85
Glossary.......................................          87
Index to Financial Statements..................         F-1
Summary Reserve Report.........................         A-1
</TABLE>
    
 
   
                                     [LOGO]
    
 
   
                             COSTILLA ENERGY, INC.
    
 
                           $100,000,000     % SENIOR
                          SUBORDINATED NOTES DUE 2006
 
                             ---------------------
 
                                   PROSPECTUS
 
                             ---------------------
 
                       NATIONSBANC CAPITAL MARKETS, INC.
 
                       PRUDENTIAL SECURITIES INCORPORATED
 
                                          , 1996
 
- --------------------------------------------------------------------------------
- --------------------------------------------------------------------------------
<PAGE>
                                    PART II
                     INFORMATION NOT REQUIRED IN PROSPECTUS
 
ITEM 13.  OTHER EXPENSES OF ISSUANCE AND DISTRIBUTION.
 
   
<TABLE>
<S>                                                                <C>
SEC registration fee.............................................  $  34,483
NASD filing fee..................................................     10,500
Blue Sky fees and expenses.......................................     10,000
Accounting fees and expenses.....................................    109,375
Engineering fees and expenses....................................    113,750
Trustee fees and expenses........................................      7,500
Legal fees and expenses..........................................    156,250
Printing and mailing expenses....................................    122,000
Miscellaneous....................................................     36,142
                                                                   ---------
      TOTAL......................................................    600,000
                                                                   ---------
                                                                   ---------
</TABLE>
    
 
ITEM 14.  INDEMNIFICATION OF DIRECTORS AND OFFICERS.
 
    Section  145 of the General Corporation Law of the State of Delaware permits
a corporation to indemnify certain persons, including officers and directors and
former officers  and  directors,  and  to purchase  insurance  with  respect  to
liability  arising out  of their capacity  or status as  officers and directors.
Such law provides  further that the  indemnification permitted thereunder  shall
not  be deemed exclusive of any other rights to which officers and directors may
be entitled under the corporation's bylaws, any agreement or otherwise.  Article
IX  of  the  Company's Certificate  of  Incorporation, included  in  Exhibit 3.1
hereto, and Article VI of the Company's Bylaws, included in Exhibit 3.2  hereto,
provide, in general, that the Company shall indemnify its directors and officers
under the circumstances defined in Section 145 of the General Corporation Law of
the  State of Delaware and gives authority  to the Company to purchase insurance
with respect to  such indemnification.  The Company may  in the  future seek  to
obtain  insurance providing for indemnification of officers and directors of the
Company and certain other persons  against liabilities and expenses incurred  by
any of them in certain stated proceedings and under certain stated conditions.
 
   
    In  addition, Section 102(b)(7) of the  General Corporation Law of the State
of Delaware  permits a  corporation  to limit  the  liability of  its  directors
subject  to certain exceptions. In accordance with Section 102(b)(7), Article VI
of the Company's Certificate of  Incorporation, included in Exhibit 3.1  hereto,
provides, in general, that no director of the Company shall be personally liable
for  (i) any  breach of  the director's duty  of loyalty  to the  Company or its
stockholders, (ii)  acts  or  omissions  not in  good  faith  or  which  involve
intentional misconduct or a knowing violation of law, (iii) unlawful payments of
dividends  or unlawful stock  repurchases or redemptions  as provided in Section
174 of  the  General Corporation  Law  of the  State  of Delaware  or  (iv)  any
transaction from which the director derived an improper personal benefit.
    
 
    The  Underwriting Agreement provides for  indemnification by the Underwriter
of the Registrant,  its directors  and officers, and  by the  Registrant of  the
Underwriter,  for certain  liabilities, including liabilities  arising under the
Securities Act of 1933 (the "Securities Act").
 
ITEM 15.  RECENT SALES OF UNREGISTERED SECURITIES.
 
   
    Prior to  the consummation  of the  Notes Offering,  the Company  issued  an
aggregate  of 3 shares of Common Stock  to Messrs. Liedtke, Grella and Musselman
in its initial capitalization,  which shares were  cancelled in connection  with
the  Corporate Reorganization,  and an aggregate  of 6,000,000  shares of Common
Stock to the four members of the LLC in the merger of the LLC with and into  the
Company.  Such shares were  not registered under the  Securities Act in reliance
upon the exemption from registration provided by Section 4(2) thereof.
    
 
                                      II-1
<PAGE>
ITEM 16.  EXHIBITS AND FINANCIAL STATEMENT SCHEDULES.
 
    (a) Exhibits
 
   
<TABLE>
<CAPTION>
 EXHIBIT
 NUMBER                                       DESCRIPTION OF EXHIBIT
- ---------  ---------------------------------------------------------------------------------------------
<C>        <S>
   **1.1   Form of Underwriting Agreement
    *3.1   Certificate of Incorporation of the Company
    *3.2   Bylaws of the Company
    *4.1   Form of Notes or Global Certificate (included as Exhibit A to the form of Indenture filed as
            Exhibit No. 4.2 to this Registration Statement)
   **4.2   Form of Indenture
   **5.1   Opinion of Cotton, Bledsoe, Tighe & Dawson, a Professional Corporation
  **10.1   Commitment Letter dated August 23, 1996 by NationsBank of Texas, N.A. to the Company
   *10.2   Lease Agreement dated January 12, 1996 between Independence Plaza, Ltd. and Costilla Energy,
            L.L.C
   *10.3   Concession Agreement dated July 6, 1996 between the Government of the Republic of Moldova and
            the Resource Development Company, Limited
   *10.4   Purchase and Joint Exploration Agreement dated February 21, 1996 between the Company and
            Resources Development Limited, L.L.C. (DE)
  **10.5   Form of Consolidation Agreement to be effective contemporaneously with closing of the
            Offerings to consummate the Corporate Reorganization
  **10.6   Form of 1996 Stock Option Plan
  **10.7   Form of Outside Directors Stock Option Plan
   *10.8   Employment Agreement between the Company and Bobby W. Page effective June 30, 1996
  **10.9   Employment Agreement between the Company and Cadell S. Liedtke to be effective
            contemporaneously with the closing of the Offerings
  **10.10  Employment Agreement between the Company and Michael J. Grella to be effective
            contemporaneously with the closing of the Offerings
  **10.11  Employment Agreement between the Company and Henry G. Musselman to be effective
            contemporaneously with the closing of the Offerings
   *10.12  Exchange Agreement dated January 5, 1995 between Costilla Petroleum Corporation and Koch Oil
            Company
   *10.13  Agreement dated January 2, 1996 between Costilla Petroleum Corporation and Frontier Oil and
            Refining Company
  **10.14  Purchase and Sale Agreement dated April 3, 1995 by and between Parker & Parsley Development
            L.P. and Parker & Parsley Producing L.P. and Parker & Parsley Gas Processing Co. as Seller
            and Costilla Petroleum Corporation and Costilla Energy, L.L.C. as Purchaser
  **10.15  Purchase and Sale Agreement dated March 8, 1996 by and between Parker & Parsley Development
            L.P. and Parker & Parsley Producing L.P. and Parker & Parsley Gas Processing Co. as Seller
            and Costilla Petroleum Corporation and Costilla Energy, L.L.C. as Purchaser
  **10.16  Supplemental Agreement to Purchase and Joint Exploration Agreement dated August 7, 1996 among
            the Company, Costilla Redeco Energy, L.L.C. and Resource Development Company Limited, L.L.C.
            (DE)
  **10.17  Form of Bonus Incentive Plan
   *12.1   Computation of Ratio of Adjusted EBITDA to Interest Expense
</TABLE>
    
 
                                      II-2
<PAGE>
   
<TABLE>
<CAPTION>
 EXHIBIT
 NUMBER                                       DESCRIPTION OF EXHIBIT
- ---------  ---------------------------------------------------------------------------------------------
<C>        <S>
   *12.2   Computation of Ratio of Earnings to Fixed Charges
   *12.3   Pro Forma Computation of Ratio of ACNTA to Total Debt
  **16.1   Letter Regarding Change of Accountants
   *21.1   Subsidiaries of the Registrant
  **23.1   Consent of KPMG Peat Marwick LLP
   *23.2   Consent of Williamson Petroleum Consultants, Inc.
  **23.3   Consent of Elms, Faris & Co., P.C.
  **23.4   Consent of Cotton, Bledsoe, Tighe & Dawson, a Professional Corporation (such consent is
            included in the opinion filed as Exhibit 5.1 to this Registration Statement)
   *24.1   Power of Attorney
   *24.2   Certified copy of resolution of Board of Directors of Costilla Energy, Inc. authorizing
            signature pursuant to Power of Attorney
   *25.1   Statement of Eligibility and Qualification of Trustee under 1939 Act on Form T-1
   *27.1   Financial Data Schedule
</TABLE>
    
 
- ------------------------
   
*  Previously filed
    
   
** Filed herewith
    
 
    (b) Financial Statement Schedules.
 
ITEM 17.  UNDERTAKINGS
 
    Insofar as indemnification for liabilities arising under the Securities  Act
may  be  permitted  to  directors,  officers  and  controlling  persons  of  the
Registrant pursuant  to  the  provisions  described  under  Item  14  above,  or
otherwise, the Registrant has been advised that in the opinion of the Securities
and  Exchange  Commission,  such  indemnification is  against  public  policy as
expressed in the Securities Act and  is, therefore, unenforceable. In the  event
that  a  claim  for indemnification  against  such liabilities  (other  than the
payment by the Registrant of expenses incurred or paid by a director, officer of
controlling person of the  Registrant in the successful  defense of any  action,
suit or proceeding) is asserted by such directors, officer or controlling person
in  connection with the securities being registered, the Registrant will, unless
in the  opinion  of its  counsel  the matter  has  been settled  by  controlling
precedent,  submit to a  court of appropriate  jurisdiction the question whether
such indemnification  by  it  is  against public  policy  as  expressed  in  the
Securities Act and will be governed by the final adjudication of such issue.
 
    The   undersigned  Registrant  hereby  undertakes   that,  for  purposes  of
determining any liability under the Securities Act, (i) the information  omitted
from  the Prospectus  filed as part  of this Registration  Statement in reliance
upon Rule 430A under the  Securities Act and contained  in a form of  Prospectus
filed  by the Registrant pursuant  to Rule 424(b)(1) or  (4) or 497(h) under the
Securities Act shall be deemed to be part of this Registrant Statement as of the
time it  was declared  effective  and (ii)  each post-effective  amendment  that
contains a form of prospectus shall be deemed to be a new Registration Statement
relating  to the securities offered therein, and the offering of such securities
at that time shall be deemed to be the initial bona fide offering thereof.
 
                                      II-3
<PAGE>
                                   SIGNATURES
 
   
    Pursuant  to the requirements of the  Securities Act of 1933, the Registrant
has duly caused this Registration  Statement to be signed  on its behalf by  the
undersigned,  thereunto duly authorized in the  City of Midland, State of Texas,
on August 30, 1996.
    
 
                                          COSTILLA ENERGY, INC.
                                          (Registrant)
 
                                          By:                 *
                                          --------------------------------------
                                                      Michael J. Grella
                                                PRESIDENT AND CHIEF OPERATING
                                                         OFFICER
 
    Pursuant  to  the  requirements  of   the  Securities  Act  of  1933,   this
Registration Statement has been signed by the following persons on behalf of the
Registrant and in the capacities and on the dates indicated.
 
   
<TABLE>
<CAPTION>
                      SIGNATURE                                   TITLE                  DATE
- ------------------------------------------------------  -------------------------  ----------------
 
<C>                                                     <S>                        <C>
                          *                             Chairman of the Board,
     -------------------------------------------         Chief Executive Officer   August 30, 1996
                  Cadell S. Liedtke                      and Director
 
                          *                             President, Chief
     -------------------------------------------         Operating Officer and     August 30, 1996
                  Michael J. Grella                      Director
 
                          *
     -------------------------------------------        Executive Vice President   August 30, 1996
                  Henry G. Musselman                     and Director
 
                  /s/ BOBBY W. PAGE                     Senior Vice Present,
     -------------------------------------------         Treasurer and Chief       August 30, 1996
                    Bobby W. Page                        Financial Officer
 
                          *
     -------------------------------------------        Director                   August 30, 1996
                   Jerry J. Langdon
 
                          *
     -------------------------------------------        Director                   August 30, 1996
                     W.D. Kennedy
 

*By:               /s/ BOBBY W. PAGE
     -------------------------------------------
                    Bobby W. Page
                   ATTORNEY-IN-FACT
</TABLE>
    
 
                                      II-4
<PAGE>
                               INDEX TO EXHIBITS
 
   
<TABLE>
<CAPTION>
 EXHIBIT
 NUMBER                                       DESCRIPTION OF EXHIBIT
- ---------  ---------------------------------------------------------------------------------------------
<C>        <S>
   **1.1   Form of Underwriting Agreement
    *3.1   Certificate of Incorporation of the Company
    *3.2   Bylaws of the Company
    *4.1   Form of Notes or Global Certificate (included as Exhibit A to the form of Indenture filed as
            Exhibit No. 4.2 to this Registration Statement)
   **4.2   Form of Indenture
   **5.1   Opinion of Cotton, Bledsoe, Tighe & Dawson, a Professional Corporation
  **10.1   Commitment Letter dated August 29, 1996 by NationsBank of Texas, N.A. to the Company
   *10.2   Lease Agreement dated January 12, 1996 between Independence Plaza, Ltd. and Costilla Energy,
            L.L.C
   *10.3   Concession Agreement dated July 6, 1996 between the Government of the Republic of Moldova and
            the Resource Development Company, Limited
   *10.4   Purchase and Joint Exploration Agreement dated February 21, 1996 between the Company and
            Resources Development Limited, L.L.C. (DE)
  **10.5   Form of Consolidation Agreement to be effective contemporaneously with closing of the
            Offerings to consummate the Corporate Reorganization
  **10.6   Form of 1996 Stock Option Plan
  **10.7   Form of Outside Directors Stock Option Plan
   *10.8   Employment Agreement between the Company and Bobby W. Page effective June 30, 1996
  **10.9   Employment Agreement between the Company and Cadell S. Liedtke to be effective
            contemporaneously with the closing of the Offerings
  **10.10  Employment Agreement between the Company and Michael J. Grella to be effective
            contemporaneously with the closing of the Offerings
  **10.11  Employment Agreement between the Company and Henry G. Musselman to be effective
            contemporaneously with the closing of the Offerings
   *10.12  Exchange Agreement dated January 5, 1995 between Costilla Petroleum Corporation and Koch Oil
            Company
   *10.13  Agreement dated January 2, 1996 between Costilla Petroleum Corporation and Frontier Oil and
            Refining Company
  **10.14  Purchase and Sale Agreement dated April 3, 1995 by and between Parker & Parsley Development
            L.P. and Parker & Parsley Producing L.P. and Parker & Parsley Gas Processing Co. as Seller
            and Costilla Petroleum Corporation and Costilla Energy, L.L.C. as Purchaser
  **10.15  Purchase and Sale Agreement dated March 8, 1996 by and between Parker & Parsley Development
            L.P. and Parker & Parsley Producing L.P. and Parker & Parsley Gas Processing Co. as Seller
            and Costilla Petroleum Corporation and Costilla Energy, L.L.C. as Purchaser
  **10.16  Supplemental Agreement to Purchase and Joint Exploration Agreement dated August 7, 1996 among
            the Company, Costilla Redeco Energy, L.L.C. and Resource Development Company Limited, L.L.C.
            (DE)
  **10.17  Form of Bonus Incentive Plan
   *12.1   Computation of Ratio of Adjusted EBITDA to Interest Expense
   *12.2   Computation of Ratio of Earnings to Fixed Charges
   *12.3   Pro Forma Computation of Ratio of ACNTA to Total Debt
  **16.1   Letter Regarding Change of Accountants
</TABLE>
    
<PAGE>
   
<TABLE>
<CAPTION>
 EXHIBIT
 NUMBER                                       DESCRIPTION OF EXHIBIT
- ---------  ---------------------------------------------------------------------------------------------
<C>        <S>
   *21.1   Subsidiaries of the Registrant
  **23.1   Consent of KPMG Peat Marwick LLP
   *23.2   Consent of Williamson Petroleum Consultants, Inc.
  **23.3   Consent of Elms, Faris & Co., P.C.
  **23.4   Consent of Cotton, Bledsoe, Tighe & Dawson, a Professional Corporation (such consent is
            included in the opinion filed as Exhibit 5.1 to this Registration Statement)
   *24.1   Power of Attorney
   *24.2   Certified copy of resolution of Board of Directors of Costilla Energy, Inc. authorizing
            signature pursuant to Power of Attorney
   *25.1   Statement of Eligibility and Qualification of Trustee under 1939 Act on Form T-1
   *27.1   Financial Data Schedule
</TABLE>
    
 
- ------------------------
   
*  Previously filed
    
   
** Filed herewith
    

<PAGE>
   
                                                     [DRAFT of August 28, 1996]
    

                                 $100,000,000


                            COSTILLA ENERGY, INC.

                            ____% NOTES DUE 2006


                           UNDERWRITING AGREEMENT


                                                       ___________  ___, 1996



NationsBanc Capital Markets, Inc.
Prudential Securities Incorporated
c/o NationsBanc Capital Markets, Inc. 
NationsBank Corporate Center
100 North Tryon Street
Charlotte, North Carolina 28255

Dear Sirs: 
   
     SECTION 1.  INTRODUCTORY.  Costilla Energy, Inc., a Delaware corporation 
(the "Company"), confirms its agreement with the several Underwriters named 
in Schedule I hereto (the "Underwriters"), to issue and sell $100,000,000 
principal amount of its ____% Notes due 2006 (the "Notes"). The Notes are to 
be issued pursuant to the provisions of an indenture dated as of 
_____________, 1996 (the "Indenture") between the Company and 
___________________, as trustee (the "Trustee").   It is understood and 
agreed to by all parties hereof that, prior to the Closing Date (as 
hereinafter defined), the Company will issue in a public offering __________ 
shares of its common stock (the "Stock Offering").  The Company hereby agrees 
with the Underwriters as follows: 

     SECTION 2.  REPRESENTATIONS, WARRANTIES AND AGREEMENTS OF THE COMPANY.  
The Company represents and warrants to, and agrees with, the several 
Underwriters that: 
    
          (a)      A registration statement on Form S-1 (File No. 
     333-________) with respect to the Notes (i) has been prepared by the 
     Company in conformity with the requirements of the Securities Act of 
     1933, as amended (the "Act"), and the rules and regulations (the "Rules 


<PAGE>


     and Regulations") of the Securities and Exchange Commission (the 
     "Commission") thereunder, (ii) has been filed with the Commission under 
     the Act and (iii) either has become effective under the Act and is not 
     proposed to be amended or is proposed to be amended by amendment or 
     post-effective amendment.  If the Company does not propose to amend such 
     registration statement and if any post-effective amendment to such 
     registration statement has been filed with the Commission prior to the 
     execution and delivery of this Agreement, the most recent such amendment 
     has been declared effective by the Commission.  Copies of such 
     registration statement as amended to date have been delivered by the 
     Company to you.  For purposes of this Agreement, "Effective Time" means 
     the date and the time as of which such registration statement, or the 
     most recent post-effective amendment thereto, if any, was declared 
     effective by the Commission; "Effective Date" means the date of the 
     Effective Time; "Preliminary Prospectus" means each prospectus included 
     in such registration statement, or amendments thereof, before it became 
     effective under the Act and any prospectus filed with the Commission by 
     the Company with the consent of the Underwriters pursuant to Rule 424(a) 
     of the Rules and Regulations prior to the filing of the Prospectus; 
     "Registration Statement" means such registration statement, as amended 
     at the Effective Time, including any documents incorporated by reference 
     therein and, if the Effective Date is on or before the date of this 
     Agreement, all information contained in the final prospectus filed with 
     the Commission pursuant to Rule 424(b) of the Rules and Regulations 
     ("Rule 424(b)") in accordance with Section 5(a) hereof and deemed to be 
     a part thereof as of the Effective Time pursuant to the Rules and 
     Regulations; "Prospectus" means the form of prospectus relating to the 
     Notes, as first used to confirm sales of the Notes; and "described in 
     the Prospectus" or "disclosed in the Prospectus" means described or 
     disclosed, as applicable, in the Prospectus.  The Commission has not 
     issued any order preventing or suspending the use of any Preliminary 
     Prospectus or the Prospectus.

          (b)  At the Effective Time and at all times subsequent thereto up 
     to the Closing Date hereinafter mentioned, the Registration Statement 
     and the Prospectus, and any amendments or supplements thereto, conform 
     in all material respects with the requirements of the Act and the Rules 
     and Regulations, and at the Effective Time the Registration Statement 
     did not include any untrue statement of a material fact or omit to state 
     any material fact required to be stated therein or necessary to make the 
     statements therein not misleading, and the Prospectus, as amended or 
     supplemented at the Closing Date, if applicable, did not contain any 
     untrue statement of a material fact or omit to state a material fact 
     necessary to make the statements contained therein, in the light of the 
     circumstances under which they were made, not misleading; except that 
     the foregoing does not apply to (i) that part of the Registration 
     Statement that constitutes the Statement of Eligibility and 
     Qualification (Form T-1) under the Trust Indenture Act of 1939, as 
     amended (the "1939 Act"), of the Trustee, and (ii) statements or 
     omissions in the Registration Statement or the Prospectus, as amended or 
     supplemented if applicable, based upon written information furnished to 
     the Company by any Underwriter through you specifically for use therein. 

          (c)  The consolidated financial statements included in the 
     Registration Statement and Prospectus present fairly the consolidated 
     financial position of the Company and its consolidated subsidiaries as 
     at the dates indicated and the results of their operations and the 


                                     -2-

<PAGE>


     changes in their consolidated financial position for the periods 
     specified; said financial statements have been prepared in conformity 
     with generally accepted accounting principles applied on a consistent 
     basis during the periods involved, except as indicated therein; and the 
     supporting schedules included in the Registration Statement present 
     fairly the information required to be stated therein.  The pro forma 
     financial statements set forth in the Registration Statement and the 
     Prospectus (the "pro forma financial statements") have been prepared in 
     accordance with the applicable accounting requirements of Rule 11-02 of 
     Regulation S-X; the pro forma adjustments reflected in the pro forma 
     financial statements have been properly applied to the historical 
     amounts in the compilation of such statements; and the assumptions used 
     in the preparation of the pro forma financial statements are, in the 
     opinion of the Company, reasonable.

          (d)  Since the respective dates as of which information is given in 
     the Registration Statement and the Prospectus, except as otherwise 
     stated therein, (i) there has been no material adverse change in the 
     condition, financial or otherwise, earnings, affairs or business 
     prospects of the Company and its subsidiaries considered as a whole, 
     whether or not arising in the ordinary course of business and (ii) there 
     have been no material transactions entered into by the Company or any of 
     its subsidiaries other than those in the ordinary course of business. 

          (e)  The Company has been duly incorporated and is validly existing 
     as a corporation in good standing under the laws of the State of 
     Delaware with corporate power and authority to own, lease and operate 
     its properties and conduct its business as described in the Registration 
     Statement; and the Company is duly qualified as a foreign corporation to 
     transact business and is in good standing in each jurisdiction in which 
     it owns or leases properties or in which the conduct of its business 
     requires such qualification, except to the extent that the failure to be 
     so qualified or be in good standing would not have a material adverse 
     effect on the Company and its subsidiaries considered as a whole. 

          (f)  Each of the subsidiaries of the Company has been duly 
     incorporated or organized and is validly existing as a corporation or 
     limited liability company in good standing under the laws of the 
     jurisdiction of its formation, has corporate power and authority to own, 
     lease and operate its properties and conduct its business as described 
     in the Registration Statement and is duly qualified as a foreign 
     corporation or limited liability company to transact business and is in 
     good standing in each jurisdiction in which it owns or leases properties 
     or in which the conduct of its business requires such qualification, 
     except to the extent that the failure to be so qualified or be in good 
     standing would not have a material adverse effect on the Company and its 
     subsidiaries considered as a whole; all of the issued and outstanding 
     capital stock or other equity interest of each subsidiary has been duly 
     authorized and validly issued and is fully paid and nonassessable, and 
     all such capital stock or other equity interest of each subsidiary is 
     owned by the Company, directly or through subsidiaries, free and clear 
     of any mortgage, pledge, lien, encumbrance, claim or equity. 

          (g)  Neither the Company nor any of its subsidiaries is (i) 
     in violation of its or any of their charters or by-laws or other 
     organizational documents or (ii) in default in the 


                                     -3-

<PAGE>

     performance or observance of any obligation, agreement, covenant or 
     condition contained in any contract, indenture, mortgage, loan 
     agreement, note, lease or other instrument to which it or any of them is 
     a party or by which it or any of them or their properties may be bound 
     except to the extent that such default would not have a material adverse 
     effect on the Company and its subsidiaries considered as a whole; no 
     consent, approval, authorization or order of any court or governmental 
     authority or agency is required for the consummation by the Company of 
     the transactions contemplated by this Agreement, except such as may be 
     required under the Act, the 1939 Act, the Rules and Regulations or state 
     securities or Blue Sky laws; and the execution and delivery of this 
     Agreement, the Indenture and the Notes and the consummation of the 
     transactions contemplated herein and therein will not conflict with or 
     constitute a breach of, or default under, or result in the creation or 
     imposition of any lien, charge or encumbrance upon any property or 
     assets of the Company or any of its subsidiaries pursuant to, any 
     material contract, indenture, mortgage, loan agreement, note, lease or 
     other instrument to which the Company or any of its subsidiaries is a 
     party or by which it or any of them may be bound or to which any of the 
     property or assets of the Company or any of its subsidiaries is subject, 
     nor will such action result in any violation of or conflict with the 
     provisions of the charter or by-laws of the Company or any law, 
     administrative regulation or administrative or court decree. 

          (h)  The Company and its subsidiaries possess adequate 
     certificates, authorities, licenses or permits issued by the appropriate 
     state, federal or foreign regulatory agencies or bodies necessary to 
     conduct the business now operated by them, and neither the Company nor 
     any of its subsidiaries has received any notice of proceedings relating 
     to the revocation or modification of any such certificate, authority, 
     license or permit which, singly or in the aggregate, if the subject of 
     an unfavorable decision, ruling or finding, would materially adversely 
     affect the condition, financial or otherwise, earnings, affairs or 
     business prospects of the Company and its subsidiaries considered as a 
     whole.

          (i)  Except as set forth in the Prospectus, there is no action, 
     suit or proceeding before or by any court or governmental agency or 
     body, domestic or foreign, now pending or, to the knowledge of the 
     Company, threatened against or affecting the Company or any of its 
     subsidiaries, which might result in any material adverse change in the 
     condition, financial or otherwise, earnings, affairs or business 
     prospects of the Company and its subsidiaries considered as a whole, or 
     might materially and adversely affect the properties or assets thereof 
     or might materially and adversely affect the offering of the Notes; and 
     there are no material contracts or other documents which are required to 
     be filed as exhibits to the Registration Statement by the Act or by the 
     Rules and Regulations which have not been so filed.

          (j)  The Company and each of its subsidiaries has good and 
     defensible title to all property and assets owned by it and necessary in 
     the conduct of the business of the Company or such subsidiary in each 
     case free and clear of all liens, encumbrances and defects except (i) 
     such as are referred to in the Prospectus or (ii) such as do not 
     materially adversely affect the value of such property to the Company or 
     such subsidiary, and do not interfere with the use made and proposed to 
     be made of such property by the Company or such subsidiary to 


                                     -4-

<PAGE>

     an extent that such interference would have a material adverse effect on 
     the Company or such subsidiary.

   
          (k)  This Agreement has been duly authorized, executed and      
     delivered by the Company and is a valid and binding agreement of the 
     Company (subject, as to the enforcement of remedies, to applicable 
     bankruptcy, reorganization, insolvency, moratorium or other laws 
     affecting creditors' rights generally from time to time in effect and to 
     general equitable principles), except as rights to indemnity hereunder 
     may be limited by applicable law.

          (l)  The Indenture has been duly authorized, executed and delivered 
     by the Company and duly qualified under the 1939 Act, and constitutes a 
     legal, valid and binding instrument enforceable against the Company in 
     accordance with its terms (subject, as to the enforcement of remedies, 
     to applicable bankruptcy, reorganization, insolvency, moratorium or 
     other laws affecting creditors' rights generally from time to time in 
     effect and to general equitable principles).
    
          (m)  The Notes have been duly and validly authorized by the Company 
     for issuance and sale to the Underwriters pursuant to this Agreement 
     and, when executed by the Company and authenticated by the Trustee in 
     accordance with the Indenture and delivered to the Underwriters against 
     payment therefor in accordance with the terms hereof, will have been 
     validly issued and delivered, free of any preemptive or similar rights, 
     and will constitute valid and binding obligations of the Company 
     entitled to the benefits of the Indenture and enforceable against the 
     Company in accordance with their terms (subject, as to the enforcement 
     of remedies, to applicable bankruptcy, reorganization, insolvency, 
     moratorium or other laws affecting creditors' rights generally from time 
     to time in effect and to general equitable principles).  The Notes 
     conform, or will conform, to the description thereof in the Registration 
     Statement and the Prospectus.  Neither the filing of the Registration 
     Statement nor the offering or sale of the Notes as contemplated by this 
     Agreement gives rise to any rights, other than those which have been 
     duly waived or satisfied, for or relating to the registration of any 
     securities of the Company.  The capitalization of the Company as of  the 
     date of the most recent balance sheet included in the Prospectus is as 
     set forth in the Prospectus.  The Company has all requisite corporate 
     power and authority to issue, sell, and deliver the Notes in accordance 
     with and upon the terms and conditions set forth in this Agreement and 
     in the Registration Statement and Prospectus.  All corporate action 
     required to be taken by the Company for the authorization, issuance, 
     sale and delivery of the Notes to be sold by the Company hereunder has 
     been validly and sufficiently taken.
   
          (n)  The Subsidiary Guarantees (as defined in the Indenture) when 
     executed and endorsed upon the Notes and delivered in accordance with 
     the terms of the Indenture, such Subsidiary Guarantees will be valid and 
     binding obligations of the Subsidiary Guarantors (as defined in the 
     Indenture), enforceable against the Subsidiary Guarantors in accordance 
     with their terms (subject, as to the enforcement of remedies, to 
     applicable bankruptcy, reorganization, insolvency, moratorium or other 
     laws affecting 
    
                                     -5-

<PAGE>

   
     creditors' rights generally from time to time in effect and to general 
     equitable principles); the form of notation to be set forth on each Note 
     to evidence the Subsidiary Guarantees will be in the form contemplated 
     by the Indenture; and the Subsidiary Guarantees conform in all material 
     respects to the description thereof contained in the Registration 
     Statement and the Prospectus.  
    
          (o)  KPMG Peat Marwick, LLP and Elms Faris & Company, who have 
     certified certain financial statements of the Company and its 
     subsidiaries, are independent public accountants within the meaning of 
     the Securities Act and the rules and regulations thereunder.

          (p)  The Company and each of its subsidiaries maintain a system of 
     internal accounting controls sufficient to provide reasonable assurances 
     that (i) transactions are executed in accordance with management's 
     general or specific authorizations; (ii) transactions are recorded as 
     necessary to permit preparation of financial statements in conformity 
     with generally accepted accounting principles and to maintain asset 
     accountability; (iii) access to assets is permitted only in accordance 
     with management's general or specific authorization; and (iv) the 
     recorded accountability for assets is compared with the existing assets 
     at reasonable intervals and appropriate action is taken with respect to 
     any differences.

          (q)  Neither the Company nor any of its subsidiaries is now or, 
     after giving effect to the issuance of the Notes and the Subsidiary 
     Guarantees, will be (i) insolvent, (ii) left with unreasonably small 
     capital, on a pro forma basis, with which to engage in its anticipated 
     businesses or (iii) incurring debts beyond its ability to pay such debts 
     as they become due.

          (r)  The Company and its subsidiaries own or otherwise possess the 
     right to use all patents, trademarks, service marks, trade names and 
     copyrights, all applications and registrations for each of the 
     foregoing, and all other proprietary rights and confidential information 
     used in the conduct of their respective businesses as currently 
     conducted; and neither the Company nor any of its subsidiaries has 
     received any notice or is otherwise aware, of any infringement of or 
     conflict with the rights of any third party with respect to any of the 
     foregoing which, singly or in the aggregate, if the subject of an 
     unfavorable decision, ruling or finding, would result in a material 
     adverse effect on the Company.

          (s)  The Company and each of its subsidiaries are insured by 
     insurers of recognized financial responsibility against such losses and 
     risks and in such amounts as are prudent and customary in the businesses 
     in which they are engaged; neither the Company nor 


                                     -6-

<PAGE>


     any of its subsidiaries have been refused any insurance coverage sought 
     or applied for; and neither the Company nor any of its subsidiaries have 
     any reason to believe that they will not be able to renew their existing 
     insurance coverage as and when such coverage expires or to obtain 
     similar coverage from similar insurers as may be necessary to continue 
     its business at a cost that would not have a material adverse effect on 
     the Company.

          (t)  The Company has complied and will comply with all the 
     provisions of Section 517.075, Florida Statutes (Chapter 92-198, Laws of 
     Florida) and all regulations promulgated thereunder relating to issuers 
     doing business in Cuba.

          (u)  There are no contracts or other documents which are required 
     to be described in the Prospectus or filed as exhibits to the 
     Registration Statement by the Act or by the Rules and Regulations which 
     have not been described in the Prospectus or filed as exhibits to the 
     Registration Statement or incorporated therein by reference as permitted 
     by the Rules and Regulations.

          (v)  There has been no storage, disposal, generation, manufacture, 
     refinement, transportation, handling or treatment of toxic wastes, 
     medical wastes, hazardous wastes or hazardous substances by the Company 
     or any of its subsidiaries (or, to the knowledge of the Company, any of 
     their predecessors in interest) at, upon or from any of the property now 
     or previously owned or leased by the Company or its subsidiaries in 
     violation of any applicable law, ordinance, rule, regulation, order, 
     judgment, decree or permit, or which would require remedial action under 
     any applicable law, ordinance, rule, regulation, order, judgment, decree 
     or permit, except for any violation or remedial action which would not 
     have, or could not be reasonably likely to have, singularly or in the 
     aggregate with all such violations and remedial actions, a material 
     adverse effect on the general affairs, management, financial position, 
     stockholders' equity or results of operations of the Company and its 
     subsidiaries; there has been no material spill, discharge, leak, 
     emission, injection, escape, dumping or release of any kind onto such 
     property or into the environment surrounding such property of any toxic 
     wastes, medical wastes, solid wastes, hazardous wastes or hazardous 
     substances due to or caused by the Company or any of its subsidiaries or 
     with respect to which the Company or any of its subsidiaries have 
     knowledge, except for any such spill, discharge, leak, emission, 
     injection, escape, dumping or release which would not have or would not 
     be reasonably likely to have, singularly or in the aggregate with all 
     such spills, discharges, leaks, emissions, injections, escapes, dumpings 
     and releases, a material adverse effect on the general affairs, 
     management, financial position, stockholders' equity or results of 
     operations of the Company and its subsidiaries; and the terms "hazardous 
     wastes," "toxic wastes," "hazardous substances" and "medical wastes" 
     shall have the meanings specified in any applicable local, state, 
     federal and foreign laws or regulations with respect to environmental 
     protection.

     SECTION 3.  PURCHASE, SALE AND DELIVERY OF NOTES.  Subject to the terms 
and conditions and in reliance upon the representations and warranties herein 
set forth, the Company agrees to sell to each Underwriter, and each 
Underwriter agrees, severally and not jointly, to 


                                     -7-

<PAGE>

purchase from the Company at a purchase price of _______% of the principal 
amount per Note (the "purchase price per Note"), plus accrued interest, if 
any, from _________, 1996 to the date of payment and delivery, the respective 
principal amount of Notes set forth opposite such Underwriter's name in 
Schedule I hereto.

     Delivery of and payment for the Notes shall be made at __________ a.m. 
New York City time, on __________, 1996, or such later date (not later than 
__________, 1996) as you shall designate, which date and time may be 
postponed by agreement between you and the Company or as provided in Section 
11 hereof (such date and time of delivery and payment for the Notes being 
herein called the "Closing Date").  Delivery of the Notes shall be made to 
you for the respective accounts of the Underwriters against payment by the 
Underwriters through you of the purchase price thereof to or upon the order 
of the Company by certified or official bank check or checks payable in 
immediately available funds; PROVIDED, that the amount of such payment shall 
be reduced by one days' interest on the amount of gross proceeds at the 
Underwriters' cost of borrowing such funds plus any other expenses associated 
with such payment of immediately available funds. Delivery of the Notes shall 
be made at such location as you shall reasonably designate at least one 
business day in advance of the Closing Date and payment for the Notes shall 
be made at the office of Baker & Botts, L.L.P. ("Counsel for the 
Underwriters"), One Shell Plaza, 910 Louisiana, Houston, Texas  77002.

     The Company, Prudential Securities Incorporated (the "Independent 
Underwriter") and the other Underwriter agree to comply in all material 
respects with all of the requirements of Rule 2720 of the Conduct Rules of 
the National Association of Securities Dealers, Inc. ("Rule 2720") applicable 
to them in connection with the offering and sale of the Notes.  The Company 
agrees to cooperate with Underwriters, to enable the Underwriters to comply 
with Rule 2720 and the Independent Underwriter to perform the services 
contemplated by this Agreement.

     The Independent Underwriter hereby consents to the references to it as 
set forth under the caption "Underwriting" in the Prospectus.

     SECTION 4.  OFFERING BY UNDERWRITERS.  The several Underwriters will 
offer the Notes for sale to the public on the terms as set forth in the 
Prospectus. 

     SECTION 5.  COVENANTS OF THE COMPANY.  The Company covenants and agrees 
with the each Underwriter that:

          (a)  The Company will advise you promptly of any proposal to amend 
     or supplement the registration statement as filed, or the related 
     prospectus, prior to the effectiveness of the Registration Statement, 
     and will not effect such amendment or supplement without your consent, 
     which will not be unreasonably withheld; the Company will also advise 
     you promptly of the filing or effectiveness of any amendment or 
     supplement to the Registration Statement or the Prospectus, the receipt 
     of any comments from the Commission with respect to the Registration 
     Statement or the Prospectus or any amendment or supplement thereto, and 
     of receipt of notification of the institution by the Commission or any 
     state of any stop order proceedings in respect of the Registration 
     Statement or the initiation or threatening of any proceeding for such 
     purpose, and will use every reasonable 


                                     -8-

<PAGE>

     effort to prevent the issuance of any such stop order and to obtain as 
     soon as possible its lifting, if issued. The Company will also notify 
     you promptly of any request by the Commission for any amendment of or 
     supplement to the Registration Statement or the Prospectus or for 
     additional information; the Company will prepare and file with the 
     Commission, promptly upon your request, any amendments or supplements to 
     the Registration Statement or the Prospectus which, in your opinion, may 
     be necessary or advisable in connection with the distribution of the 
     Notes; and the Company will not file any amendment or supplement to the 
     Registration Statement or the Prospectus or file any document under the 
     Exchange Act before the termination of the offering of the Notes by the 
     Underwriters if such document would be deemed to be incorporated by 
     reference into the Prospectus, which filing is not consented to by the 
     Underwriters after reasonable notice thereof, such consent not to be 
     unreasonably withheld or delayed.

          (b)  If, during such period of time after the first date of the 
     public offering of the Notes as in the opinion of counsel for the 
     Underwriters a prospectus relating to the Notes is required by law to be 
     delivered in connection with sales by an Underwriter or dealer, any 
     event occurs as a result of which the Prospectus as then amended or 
     supplemented would, in the judgment of the Underwriters and their 
     counsel, include an untrue statement of a material fact, or omit to 
     state a material fact necessary to make the statements therein, in light 
     of the circumstances under which they were made, not misleading, or if 
     it is necessary at any time to amend the Prospectus to comply with the 
     Act or any other law, subject to the requirements of paragraph (a) of 
     this Section 5, the Company promptly will prepare and file with the 
     Commission an amendment or supplement which will correct such statement 
     or omission or an amendment which will effect such compliance and will 
     notify you of such filing, and will prepare and provide to the 
     Underwriters pursuant to paragraph (c) of this Section 5, an amended 
     Prospectus or a supplement to the Prospectus which will correct such 
     statement or omission or effect such compliance. 

          (c)  The Company will make generally available to the Company's 
     security holders as soon as practicable an earning statement covering 
     the twelve month period ending September 30, 1997, that satisfies the 
     provisions of Section 11(a) of the Act and the Rules and Regulations 
     including, without limitation, Rule 158. 

          (d)  The Company will deliver to you, free of charge, (i) as many 
     signed and conformed copies of the Registration Statement (as originally 
     filed) and of each amendment thereto (including exhibits filed therewith 
     or incorporated by reference therein) and of the Prospectus as you may 
     reasonably request and (ii) a conformed copy of the Registration 
     Statement and each amendment thereto for each of the Underwriters and 
     will also deliver to each Underwriter, free of charge, during the period 
     referred to in paragraph (b) of this Section 5, as many copies of the 
     Prospectus and any amendments and supplements thereto as such 
     Underwriter may reasonably request.  

          (e)  The Company will arrange to qualify the Notes for offering and 
     sale under the applicable securities laws of such states and other 
     jurisdictions of the United States as the Underwriters may designate, 
     and will maintain such qualifications in effect for as long as 


                                     -9-

<PAGE>


     may be required for the distribution of the Notes.  The Company will 
     file such statements and reports as may be required by the laws of each 
     jurisdiction in which the Notes have been qualified as above provided.

          (f)  During the period of five years hereafter, the Company will 
     furnish to you and upon request, to each of the other Underwriters, as 
     soon as practicable after the end of each fiscal year, a copy of its 
     annual report to stockholders for such year, and the Company will 
     furnish to you (i) as soon as available, a copy of each report or 
     definitive proxy statement of the Company filed with the Commission 
     under the Exchange Act or mailed to stockholders, and (ii) from time to 
     time, such other information concerning the Company as you may 
     reasonably request.

          (g)  Until the termination of the offering of the Notes, the 
     Company shall timely file all documents and amendments to previously 
     filed documents required to be filed by it pursuant to Section 12, 13, 
     14 or 15(d) of the Exchange Act.

          (h)  The Company shall apply the net proceeds from the sale of the 
     Notes as set forth in the Prospectus.

          (i)  The Company will cooperate with you and use its best efforts 
     to permit the Notes to be eligible for clearance and settlement through 
     The Depository Trust Company.

          (j)  The Company will not, until [_____] days following the Closing 
     Date, without your prior written consent, offer, sell or contract to 
     sell in a public offering, or otherwise dispose of in a public offering, 
     directly or indirectly, or announce the public offering of, any debt 
     securities issued or guaranteed by the Company (other than the Notes).

     SECTION 6.  CONDITIONS OF THE OBLIGATIONS OF THE UNDERWRITERS.  The 
obligations of the several Underwriters to purchase and pay for the Notes on 
the Closing Date will be subject to the accuracy of the representations and 
warranties on the part of the Company herein as of the date hereof and as of 
the Closing Date with the same force and effect as if made as of that date, 
to the accuracy of the statements of the Company made in any certificates 
pursuant to the provisions hereof, to the performance by the Company of its 
obligations hereunder and to the following additional conditions:

          (a)  The Registration Statement shall have become effective (or if 
     a post-effective amendment is required to be filed under the Act, such 
     post-effective amendment shall have become effective) not later than 
     5:00 p.m., New York time, on the date of this Agreement, or such later 
     time or date as shall have been consented to by you; and prior to the 
     Closing Date no stop order suspending the effectiveness of the 
     Registration Statement shall have been issued and no proceedings for 
     that purpose shall have been instituted, or to the knowledge of the 
     Company or you, shall be contemplated by the Commission. 

          (b)  You shall not have advised the Company that the Registration 
     Statement or  Prospectus, or any amendment or supplement thereto, 
     contains an untrue statement of fact 


                                     -10-

<PAGE>

         or omits to state a fact which, you have concluded, is material and 
         in the case of an omission is required to be stated therein or is 
         necessary to make the statements therein not misleading. 

              (c)  You shall have received a favorable opinion of Cotton, 
         Bledsoe, Tighe & Dawson, a Professional Corporation ("Counsel for the 
         Company"), dated the Closing Date to the effect that: 

                   (i)  The Company has been duly incorporated and is validly 
              existing as a corporation in good standing under the laws of 
              Delaware with full corporate power and authority to own, lease
              and operate its properties and conduct its business as described
              in the Registration Statement; and the Company is duly qualified
              as a foreign corporation to transact business and, to the best of
              such counsel's knowledge and information, is in good standing in 
              each jurisdiction which requires such qualification wherein it 
              owns or leases material properties or conducts material business
              except where the failure to so qualify would not have a material
              adverse effect on the properties, prospects, condition (financial
              or otherwise) or results of operations of the Company and its 
              subsidiaries taken as a whole.

                   (ii) Each of the subsidiaries of the Company has been duly 
              incorporated or organized and is validly existing as a corporation
              or limited liability company in good standing under the laws of 
              the jurisdiction of its formation, has corporate power and 
              authority to own, lease and operate its properties and conduct its
              business as described in the Registration Statement, and, to the 
              best of such counsel's knowledge and information, is duly 
              qualified as a foreign corporation or limited liability company to
              transact business and is in good standing in each jurisdiction 
              which requires such qualification wherein it owns or leases 
              material properties or conducts material business except where the
              failure to so qualify would not have a material adverse effect on 
              the properties, prospects, condition (financial or otherwise) or 
              results of operations of the Company and its subsidiaries taken as
              a whole; all of the issued and outstanding capital stock or other 
              equity interest of each subsidiary has been duly authorized and 
              validly issued and is fully paid and non-assessable, and, except 
              as otherwise set forth in the Registration Statement, all of such
              capital stock or other equity interest, to the best of such 
              counsel's knowledge and information, is owned by the Company, 
              directly or indirectly, free and clear of any mortgage, pledge, 
              lien, encumbrance, claim or equity. 

                   (iii) All of the outstanding shares of capital stock of the
              Company have been duly authorized and are validly issued, fully 
              paid and nonassessable.  To the best of such counsel's knowledge,
              neither the filing of the Registration Statement nor the offering
              or sale of the Notes as contemplated by this Agreement gives rise
              to any rights, other than those which have been waived or 
              satisfied, for or relating to the registration of any securities 
              of the Company or any of its subsidiaries, and, to the best of 
              such counsel's knowledge, no person or entity (other than the 
              Underwriters) has the right, contractual or otherwise, to cause 
              the Company to sell or otherwise issue to such person or entity, 
              or permit such person or entity to underwrite the sale 

                                    -11- 
<PAGE>

              of, any of the Notes.  The authorized equity capitalization of the
              Company as of the date of the most recent balance sheet included 
              or incorporated by reference in the Prospectus is as set forth in
              the Prospectus, and the Notes conform as to legal matters to the 
              description thereof contained in the Prospectus.  The Company has
              all requisite corporate power and authority to issue, sell and 
              deliver the Notes in accordance with and upon the terms and 
              conditions set forth in this Agreement and in the Registration 
              Statement and Prospectus.

   
                   (iv) This Agreement has been duly authorized, executed and 
              delivered by the Company.

                   (v)  The Indenture has been duly authorized, executed and 
              delivered by the Company and duly qualified under the 1939 Act, 
              and constitutes a legal, valid and binding instrument 
              enforceable against the Company in accordance with its terms 
              (subject, as to the enforcement of remedies, to applicable 
              bankruptcy, reorganization, insolvency, moratorium or other 
              laws affecting creditors' rights generally from time to time in 
              effect and to general equitable principles).
    
                   (vi) The Notes have been duly and validly authorized and, 
              when executed and authenticated in accordance with the provisions
              of the Indenture and delivered to and paid for by the Underwriters
              pursuant to this Agreement, will constitute legal, valid and 
              binding obligations of the Company entitled to the benefits of the
              Indenture (subject, as to the enforcement of remedies, to 
              applicable bankruptcy, reorganization, insolvency, moratorium or 
              other laws affecting creditors' rights generally from time to time
              in effect and to general equitable principles); and the statements
              set forth under the heading "Description of Notes" in the 
              Prospectus, insofar as such statements purport to summarize 
              certain provisions of the Notes and the Indenture, provide a fair 
              summary of such provisions.
   
                   (vii) The Subsidiary Guarantees, when delivered in 
              accordance with the terms of the Indenture, will have been 
              validly issued and delivered and will constitute valid and 
              binding obligations of the Subsidiary Guarantors, enforceable 
              against the Subsidiary Guarantors in accordance with their 
              terms (subject, as to the enforcement of remedies, to 
              applicable bankruptcy, reorganization, insolvency, 
              moratorium or other laws affecting creditors' rights generally 
              from time to time in effect and to general equitable 
              principles).
    
                   (viii) The Registration Statement is effective under the 
              Act and, to the best of such counsel's knowledge and information,
              no stop order suspending the effectiveness of the Registration 
              Statement has been issued under the Act or proceedings therefor
              initiated or threatened by the Commission.  All required filings
              by the Company under Rule 424(b) of the Rules and Regulations have
              been timely made.

                                    -12- 
<PAGE>

                   (ix) Statements set forth in the Prospectus under the 
              headings "Business and Properties--Regulation" and "Description
              of Notes," in the Registration Statement, insofar as such 
              statements constitute a summary of the legal matters, documents or
              proceedings referred to therein fairly present the information 
              called for with respect to such legal matters, documents and 
              proceedings.

                   (x)  No consent, approval, authorization or order of any 
              court or governmental authority or agency is required in 
              connection with the transactions contemplated by this Agreement,
              except such as may be required under the Act, the 1939 Act, the 
              Rules and Regulations or state securities or Blue Sky laws and 
              such other approvals (specified in such opinion) as have been 
              obtained; and, to the best of such counsel's knowledge and 
              information, the execution and delivery of this Agreement, the 
              Notes and the Indenture and the consummation of the transactions
              contemplated herein will not conflict with or constitute a breach
              of, or default under, or result in the creation or imposition of 
              any lien, charge or encumbrance upon any property or assets of the
              Company or any of its subsidiaries pursuant to, any contract, 
              indenture, mortgage, loan agreement, note, lease or other 
              instrument to which the Company or any of its subsidiaries is a 
              party or by which it or any of them may be bound or to which any 
              of the property or assets of the Company or any of its 
              subsidiaries is subject; nor will such action result in any 
              violation of the provisions of the charter or by-laws of the 
              Company, or any law, administrative regulation or administrative
              or court decree. 

                   (xi) After due inquiry, such counsel does not know of any 
              legal or governmental proceeding pending or threatened to which
              the Company or any of its subsidiaries is a  party or to which 
              any of the properties of the Company is subject that is required
              to be described in the Registration Statement or the Prospectus 
              and is not so described or of any contract or other document that
              is required to be described in the Registration Statement or the 
              Prospectus or to be filed as an exhibit to the Registration 
              Statement that is not so described or filed as required.

                   (xii) The Registration Statement and the Prospectus and 
              any further amendments or supplements thereto made by the Company
              at the time the Registration Statement and each amendment thereto
              became effective (except that no opinion need be expressed as to 
              the financial statements or notes thereto and other financial and
              statistical data contained therein) and the Form T-1 complied as 
              to form in all material respects with the applicable requirements
              of the Act and the Rules and Regulations and the 1939 Act and the
              rules and regulations thereunder. 

              Such opinion shall also contain a statement that such counsel 
     has no reason to believe that (i) the Registration Statement, as of the 
     Effective Time, or any amendment thereto (other than the engineering 
     data, financial statements and notes thereto and the other engineering,
     financial and statistical data contained therein, as to which such counsel
     need not comment), at the time it became effective, contained any untrue 
     statement of a material fact or omitted to state any material fact required
     to be stated therein or necessary in order to make the 

                                    -13- 
<PAGE>

     statements therein not misleading, or (ii) the Prospectus or any supplement
     or amendment thereto (other than the engineering data, financial statements
     and notes thereto and the other engineering, financial and statistical data
     contained therein, as to which such counsel need not comment), on such 
     Closing Date or at the time such Prospectus or supplement or amendment 
     thereto was issued contains or contained any untrue statement of a material
     fact or omits or omitted to state any material fact required to be stated 
     therein or necessary in order to make the statements therein, in light of 
     the circumstances under which they were made, not misleading.

         (d)  You shall have received from Counsel for the Underwriters such 
     opinion or opinions, dated the Closing Date, with respect to the issuance
     and sale of the Notes, the Registration Statement and Prospectus (as 
     amended or supplemented at the Closing Date) and other related matters as
     the Underwriters may reasonably require, and the Company shall have 
     furnished to such counsel such documents as they request for the purpose
     of enabling them to pass upon such matters.

         (e)  At the Closing Date there shall not have been, since the date 
     of this Agreement or since the respective dates as of which information is
     given in the Registration Statement, any material adverse change in the 
     condition, financial or otherwise, earnings, business affairs or business 
     prospects of the Company and its subsidiaries considered as a whole, 
     whether or not arising in the ordinary course of business, except as set 
     forth in or contemplated by the Prospectus (exclusive of any amendment or
     supplement thereto), and you shall have received a certificate of the 
     Company, signed by the Chairman of the Board or the President and the 
     principal financial or accounting officer of the Company, dated the Closing
     Date, to the foregoing effect, to the effect that the signers of such 
     certificate have carefully examined the Prospectus, any amendment or 
     supplement to the Prospectus and this Agreement, and to the further effect
     that (i) the representations and warranties of the Company contained in 
     this Agreement are true and correct on and as of the Closing Date with the
     same force and effect as though expressly made on and as of the Closing 
     Date, (ii) the Company has performed or complied with all agreements and
     satisfied all conditions on its part to be performed or satisfied at or 
     prior to the Closing Date and (iii) no stop order suspending the 
     effectiveness of the Registration Statement has been issued and no 
     proceedings for that purpose have been initiated or threatened by the 
     Commission or any state.

         (f)  You shall have received from KPMG Peat Marwick, LLP, independent
     public accountants, two letters, the first delivered concurrently with the
     execution of, and dated the date of, this Agreement and the other dated the
     Closing Date, addressed to the Underwriters (with conformed copies for each
     of the Underwriters), in form and substance satisfactory to you, to the 
     effect that:

              (i)  They are independent public accountants with respect to the 
         Company and its subsidiaries within the meaning of the Act and the 
         Rules and Regulations.

                                    -14- 
<PAGE>

              (ii) In their opinion, the consolidated financial statements and 
         supporting schedules of the Company and its subsidiaries and of the 
         properties acquired by the Company in certain material transactions in
         1995 and 1996 examined by them and included or incorporated by 
         reference in the Registration Statement comply as to form in all 
         material respects with the applicable accounting requirements of the
         Act and the Rules and Regulations with respect to registration 
         statements on Form S-1 and the Exchange Act and the rules and 
         regulations promulgated thereunder (the "Exchange Act Regulations").

              (iii) They have performed specified procedures, not constituting
         an audit, including a reading of the latest available interim 
         financial statements of the Company and its indicated subsidiaries, a
         reading of the minute books of the Company and such subsidiaries since
         the end of the most recent fiscal year with respect to which an audit
         report has been issued, inquiries of and discussions with certain 
         officials of the Company and such subsidiaries responsible for 
         financial and accounting matters with respect to the unaudited 
         consolidated financial statements included in the Registration 
         Statement and Prospectus and the latest available interim unaudited 
         financial statements of the Company and its subsidiaries in accordance
         with Statement of Financial Accounting Standards No. 71, and such other
         inquiries and procedures as may be specified in such letters, and on 
         the basis of such inquiries and procedures nothing came to their 
         attention that caused them to believe that: (A) the unaudited 
         consolidated financial statements of the Company and its subsidiaries 
         included in the Registration Statement and Prospectus do not comply as
         to form in all material respects with the applicable accounting 
         requirements of the Exchange Act and the Exchange Act Regulations or 
         were not fairly presented in conformity with generally accepted 
         accounting principles in the United States applied on a basis 
         substantially consistent with that of the audited financial statements
         included or incorporated by reference therein, or (B) at a specified 
         date not more than five days prior to the date of such letters, there
         was any change in the consolidated capital stock or any increase in 
         consolidated long-term debt of the Company and its subsidiaries or any
         decrease in the consolidated net current assets or members' capital of
         the Company and its subsidiaries or any increases or decreases in any 
         other items specified by the Underwriters, in each case as compared 
         with the amounts shown on the most recent balance sheet of the Company
         and its subsidiaries included or incorporated by reference in the 
         Registration Statement and Prospectus or, during the period from the 
         date of such balance sheet to a specified date not more than five days
         prior to the date of such letters, there were any decreases, as 
         compared with the corresponding period in the preceding year, in 
         consolidated net revenues or the total or per share amounts of 
         consolidated net income of the Company and its subsidiaries or any 
         increases or decreases in any other items specified by the 
         Underwriters, except in each such case as set forth in or contemplated
         by the Registration Statement and Prospectus or except for such 
         exceptions enumerated in such letters as shall have been agreed to by 
         the Underwriters and the Company.

                                    -15- 
<PAGE>

              (iv) In addition to the examination referred to in their report 
         included or incorporated by reference in the Registration Statement 
         and the Prospectus, and the specified procedures referred to in clause
         (iii) above, they have carried out certain other specified procedures,
         not constituting an audit, with respect to certain amounts, percentages
         and financial information which are included in the Registration 
         Statement and Prospectus and which are specified by the Underwriters,
         and have found such amounts, percentages and financial information to 
         be in agreement with the relevant accounting and financial records of 
         the Company and its subsidiaries identified in such letters.

              (v)  On the basis of a reading of the unaudited pro forma 
         financial statements included in the Registration Statement and 
         Prospectus; carrying out certain specified procedures; inquiries of
         certain officials of the Company and Parker & Parsley Development L.P.
         and its affiliates who have responsibility for financial and accounting
         matters; and proving the arithmetic accuracy of the application of the 
         pro forma adjustments to the historical amounts in the pro forma 
         financial statements, nothing came to their attention which caused them
         to believe that the pro forma financial statements do not comply in 
         form in all material respects with the applicable accounting 
         requirements of Rule 11-02 of Regulation S-X or that the pro forma 
         adjustments have not been properly applied to the historical amounts in
         the compilation of such statements.

         (g)  At the Closing Date, counsel for the Underwriters shall have 
     been furnished with such other documents and opinions as they may 
     reasonably  require.

         (h)  At the time of the Closing, the Notes shall have a rating of at 
     least _____ by Moody's Investors Service, Inc. and _____ by Standard & 
     Poor's Rating Service, and the Company shall have delivered to the 
     Underwriters a letter, dated the Closing Date, from each such rating agency
     or other evidence satisfactory to the Underwriters, confirming such 
     ratings.  Since the Effective Date, there shall not have occurred any 
     downgrading with respect to any debt securities of the Company or any of
     its Subsidiaries by any "nationally recognized statistical rating 
     organization" as that term is defined by the Commission for purposes of 
     Rule 436(g)(2) under the Act or any public announcement that any such 
     organization has under surveillance or review its rating of any such debt
     securities (other than an announcement with positive implications of a 
     possible upgrading, and no implication of a possible downgrading of such 
     rating).

         (i)  On or prior to the Closing Date, the closing contemplated 
     pursuant to the Stock Offering shall have occurred.

     All such opinions, certificates, letters and documents shall be in 
compliance with the provisions hereof only if they are satisfactory in form 
and substance to you and to counsel for the Underwriters.  The Company shall 
furnish to you conformed copies of such opinions, certificates, letters and 
other documents in such number as you shall reasonably request.  If any of 
the conditions specified in this Section 6 shall not have been fulfilled when 
and as required by this Agreement, this 

                                    -16- 
<PAGE>

Agreement and all obligations of the Underwriters hereunder may be canceled 
at, or at any time prior to, the Closing Date, by you.  Any such cancellation 
shall be without liability of the Underwriters to the Company.  Notice of 
such cancellation shall be given to the Company in writing, or by telegraph 
or telephone and confirmed in writing.

     SECTION 7.  PAYMENT OF EXPENSES.  The Company will pay all costs, 
expenses, fees and taxes incident to (i) the preparation by the Company, 
printing, filing and distribution under the Act of the Registration Statement 
(including financial statements and exhibits), the Prospectus, each 
preliminary prospectus and all amendments and supplements to any of them 
prior to or during the period specified in Section 5(b) (including, without 
limitation, the deliveries thereof pursuant to Section 5(d)), (ii) the 
preparation, printing (including word processing and duplication costs) and 
delivery of this Agreement, the Indenture, the Statement of Eligibility and 
Qualification of the Trustee on Form T-1, Preliminary and Supplemental Blue 
Sky Memoranda, the Notes and all other agreements, memoranda, correspondence 
and other documents printed and delivered in connection with the offering of 
the Notes, (iii) the registration with the Commission and the issuance by the 
Company of the Notes (iv) the registration or qualification of the Notes for 
offer and sale under the securities or Blue Sky laws of the several states as 
described in Section 5(e) (including the reasonable fees and disbursements of 
your counsel relating to such registration or qualification), (v) any fees or 
expenses relating to the use of book-entry notes, (vi) the fees, costs and 
charges of the Trustee, including the fees and disbursements of counsel for 
the Trustee, (vii) the fees and expenses of rating agencies, and (viii) all 
other costs and expenses incident to the performance by the Company of its 
other obligations under this Agreement.  

     If the sale of the Notes provided for herein is not consummated because 
any condition to the obligations of the Underwriters set forth in Section 6 
hereof is not satisfied, because of any termination pursuant to Section 10 
hereof or because of any refusal, inability or failure on the part of the 
Company to perform any agreement herein or comply with any provision hereof 
other than by reason of default by any of the Underwriters in payment for the 
Notes on the Closing Date, the Company will reimburse the Underwriters 
severally upon demand for all out-of-pocket expenses (including reasonable 
fees and disbursements of counsel) that shall have been incurred by them in 
connection with the proposed purchase and sale of the Notes.

   
         SECTION 8.  INDEMNIFICATION AND CONTRIBUTION.  (a)  The Company agrees
     to indemnify and hold harmless each Underwriter, the directors, officers, 
     employees and agents of each Underwriter and each person, if any, who
     controls any Underwriter within the meaning of Section 15 of the Act or
     Section 20 of the Exchange Act, from and against any and all losses, 
     claims, damages, liabilities or judgments (including without limiting the
     foregoing the reasonable legal and other expenses incurred in connection 
     with investigating or defending any action, suit or proceeding or any claim
     asserted) arising out of or based upon any untrue statement or alleged 
     untrue statement in Section 2 hereof or any untrue statement or alleged 
     untrue statement of a material fact contained in the Registration Statement
     or the Prospectus or any preliminary prospectus or in any amendment or 
     supplement thereto, or caused by any omission or alleged omission to state
     therein a material fact required to be stated therein or necessary to make
     the statements therein not misleading, except insofar as such losses, 
    
                                    -17- 
<PAGE>

     claims, damages, liabilities or expenses are caused by any such untrue 
     statement or omission or alleged untrue statement or omission based upon
     information furnished in writing to the Company by any Underwriter through
     you expressly for use therein; and shall reimburse each Underwriter 
     promptly after receipt of invoices from such Underwriter for any legal or
     other expenses as reasonably incurred by such Underwriter in connection 
     with investigating, preparing to defend or defending against or appearing
     as a third-party witness in connection with any such loss, claim, damage,
     liability or action, notwithstanding the possibility that payments for such
     expenses might later be held to be improper, in which case such payments 
     shall be promptly refunded.  This indemnity agreement will be in addition
     to any liability which the Company may otherwise have to the persons 
     referred to above in this Section 8(a).
   
         (b)  Each Underwriter agrees, severally and not jointly, to 
     indemnify and hold harmless the Company, the directors of the Company, the 
     officers of the Company who sign the Registration Statement and each 
     person, if any, who controls the Company within the meaning of either 
     Section 15 of the Act or Section 20 of the Exchange Act, to the same extent
     as the foregoing indemnity from the Company to each Underwriter, but only 
     with reference to written information relating to such Underwriter 
     furnished to the Company by or on behalf of such Underwriter through you 
     specifically for inclusion in the Registration Statement, the Prospectus, 
     any amendment or supplement thereto, or any preliminary prospectus. 
    
         (c)  Promptly after receipt by an indemnified party under this Section
     8 of notice of the commencement of any action, such indemnified party will,
     if a claim in respect thereof is to be made against the indemnifying party 
     under this Section 8, notify the indemnifying party in writing of the 
     commencement thereof; but the failure so to notify the indemnifying party
     (i) will not relieve it from liability under paragraph (a) or (b) above 
     unless and to the extent it did not otherwise learn of such action and such
     failure results in the forfeiture by the indemnifying party of substantial 
     rights and defenses and (ii) will not, in any event, relieve the 
     indemnifying party from any obligations to any indemnified party other than
     the indemnification obligation provided in paragraph (a) or (b) above.  The
     indemnifying party shall be entitled to appoint counsel of the indemnifying
     party's choice at the indemnifying party's expense to represent the 
     indemnified party in any action for which indemnification is sought (in 
     which case the indemnifying party shall not thereafter be responsible for
     the fees and expense or any separate counsel retained by the indemnified 
     party or parties except as set forth below); PROVIDED, HOWEVER, that such
     counsel shall be satisfactory to the indemnified party.  Notwithstanding 
     the indemnifying party's election to appoint counsel to represent the 
     indemnified party in an action, the indemnified party shall have the right
     to employ separate counsel (including local counsel), and the indemnifying
     party shall bear the reasonable fees, costs and expenses of such separate 
     counsel if (i) the use of counsel chosen by the indemnifying party to 
     represent the indemnified party would present such counsel with a conflict
     of interest, (ii) the actual or potential defendants in, or targets of, any
     such action include both the indemnified party and the indemnifying party 
     and the indemnified party shall have reasonably concluded that there may be
     legal defenses available to it and/or other indemnified parties which are 
     different from or additional to those available to the indemnifying party,
     (iii) the indemnifying party shall not have employed counsel satisfactory 

                                    -18- 
<PAGE>

     to the indemnified party to represent the indemnified party within a 
     reasonable time after notice of the institution of such action or (iv) the
     indemnifying party shall authorize the indemnified party to employ separate
     counsel at the expense of the indemnifying party. An indemnifying party 
     will not, without the prior written consent of the indemnified parties, 
     settle or compromise or consent to the entry of any judgment with respect
     to any pending or threatened claim, action, suit or proceeding in respect
     of which indemnification or contribution may be sought hereunder (whether
     or not the indemnified parties are actual or potential parties to such 
     claim or action) unless such settlement, compromise or consent includes an
     unconditional release of each indemnified party from all liability arising
     out of such claim, action, suit or proceeding.

   
         (d)  In the event that the indemnity provided in paragraph (a) or 
     (b) of this Section 8 is unavailable to or insufficient to hold harmless 
     an indemnified party for any reason, the Company and the Underwriters 
     agree to contribute to the aggregate losses, claims, damages and 
     liabilities (including legal or other expenses reasonably incurred in 
     connection with investigating or defending same) (collectively "Losses") 
     to which the Company on the one hand and one or more of the Underwriters 
     on the other hand may be subject in such proportion as is appropriate to 
     reflect the relative benefits received by the Company and by the 
     Underwriters from the offering of the Notes; PROVIDED, HOWEVER, that in 
     no case shall any Underwriter (except as may be provided in any 
     agreement among the Underwriters relating to the offering of the Notes) 
     be responsible for any amount in excess of the purchase discount or 
     commission applicable to the Notes purchased by such Underwriter 
     hereunder.  If the allocation provided by the immediately preceding 
     sentence is unavailable for any reason, the Company on the one hand and 
     the Underwriters on the other hand shall contribute in such proportion 
     as is appropriate to reflect not only such relative benefits but also 
     the relative fault of the Company and of the Underwriters in connection 
     with the statements or omissions which resulted in such Losses as well 
     as any other relevant equitable considerations.  Benefits received by 
     the Company shall be deemed to be equal to the total net proceeds from 
     the offering (before deducting expenses), and benefits received by the 
     Underwriters shall be deemed to be equal to the total purchase discounts 
     and commissions received by the Underwriters from the Company in 
     connection with the purchase of the Notes hereunder.  Relative fault 
     shall be determined by reference to whether any alleged untrue statement 
     or omission relates to information provided by the Company or the 
     Underwriters.  The Company and the Underwriters agree that it would not 
     be just and equitable if contribution were determined by pro rata 
     allocation or any other method of allocation which does not take into 
     account of the equitable considerations referred to above.  
     Notwithstanding the provisions of this paragraph (d), no person guilty 
     of fraudulent misrepresentation (within the meaning of Section 11(f) of 
     the Act) shall be entitled to contribution from any person who was not 
     guilty of such fraudulent misrepresentation. For purposes of this 
     Section 8, each person who controls an Underwriter within the meaning of 
     either the Act or the Exchange Act and each director, officer, employee 
     and agent of an Underwriter shall have the same rights to contribution 
     as such Underwriter, and each person who controls the Company within the 
     meaning of either the Act or Exchange Act and each officer and director 
     of the 
    
                                    -19- 
<PAGE>

     Company shall have the same rights to contribution as the Company, subject
     in each case to the applicable terms and conditions of this paragraph (d).
   
         (e)  The Company also agrees to indemnify and hold harmless Prudential 
Securities Incorporated and each person, if any, who controls Prudential 
Securities Incorporated within the meaning of either Section 15 of the Act or 
Section 20 of the Exchange Act, from and against any and all losses, claims, 
damages, liabilities and judgments incurred as a result of Prudential Securities
Incorporated's participation as a "qualified independent underwriter" within the
meaning of Section b(15) of Rule 2720 in connection with the offering of the 
Notes, except for any losses, claims, damages, liabilities and judgments 
resulting from Prudential Securities Incorporated's, or such controlling 
person's, willful misconduct or gross negligence.
    
         SECTION 9.  REPRESENTATIONS, WARRANTIES AND AGREEMENTS TO SURVIVE 
DELIVERY.  The respective agreements, representations, warranties, 
indemnities and other statements of the Company or its officers and of the 
Underwriters set forth in or made pursuant to this Agreement will remain in 
full force and effect, regardless of any investigation made by or on behalf 
of the Underwriters or the Company or any of the officers, directors or 
controlling persons referred to in Section 8 hereof, and will survive 
delivery of and payment for the Securities.  The provisions of Sections 7 and 
8 hereof shall survive the termination or cancellation of this Agreement.

         SECTION 10.  EFFECTIVENESS OF AGREEMENT AND TERMINATION. This Agreement
shall become effective upon later of (x) execution and delivery hereof by the 
parties hereto and (y) release of notification of the effectiveness of the 
Registration Statement by the Commission.

         This Agreement may be terminated for any reason at any time prior to 
the Closing Date by NationsBanc Capital Markets, Inc., in its absolute 
discretion, upon the giving of written notice of such termination to the 
Company, if at or prior to the Closing Date (i) the Company shall have 
failed, refused or been unable to perform any agreement on its part to be 
performed hereunder, (ii) any other condition of the Underwriters' obligation 
hereunder is not fulfilled, (iii) there has been, since the respective dates 
as of which information is given in the Registration Statement, any material 
adverse change in the condition, financial or otherwise, earnings, business 
affairs or business prospects of the Company and its subsidiaries considered 
as a whole, whether or not arising in the ordinary course of business, (iv) 
there has occurred any outbreak or escalation of hostilities or other 
calamity or crisis or material change in existing financial, political, 
economic or securities market conditions, the effect of which is such as to 
make it, in the judgment of NationsBanc Capital Markets, Inc., impracticable 
or inadvisable to market the Notes in the manner contemplated in the 
Prospectus or enforce contracts for the sale of the Notes, (v) reporting of 
bid and asked prices has been suspended by the Commission or by the National 
Association of Securities Dealers, Inc. or trading generally on either the 
American Stock Exchange or the New York Stock Exchange has been suspended, or 
minimum or maximum prices for trading have been fixed, or maximum ranges for 
prices for securities have been required, by either of said exchanges or by 
order of the Commission or any other governmental authority, or if a banking 
moratorium has been declared by Federal, New York or Delaware authorities or 
(vi) if there shall have come to the attention of the Underwriters any facts 
that would cause the Underwriters to believe that the Prospectus, at the time 
it was required to 

                                    -20- 
<PAGE>

be delivered to a purchaser of Notes, included an untrue statement of a 
material fact or omitted to state a material fact necessary in order to make 
the statements therein, in light of the circumstances existing at the time of 
such delivery, not misleading.  In the event of any such termination, the 
provisions of Section 7, the indemnity agreement and contribution provisions 
set forth in Section 8, and the provisions of Sections 9 and 14 shall remain 
in effect.

         SECTION 11.  DEFAULT.  If, on the Closing Date, any one or more 
Underwriters shall fail to purchase and pay for any of the Notes agreed to be 
purchased by such Underwriter or Underwriters hereunder and such failure to 
purchase shall constitute a default in the performance of its or their 
obligations under this Agreement, the remaining Underwriters shall be 
obligated severally to take up and pay for (in the respective proportions 
which the principal amount of Notes set forth opposite their names in 
Schedule I hereto bears to the aggregate principal amount of Notes set forth 
opposite the names of all the remaining Underwriters) the Notes which the 
defaulting Underwriter or Underwriters agreed but failed to purchase; 
PROVIDED, HOWEVER, that in the event that the aggregate principal amount of 
Notes which the defaulting Underwriter or Underwriters agreed but failed to 
purchase shall exceed 10% of the aggregate principal amount of Notes set 
forth in Schedule I hereto, the remaining Underwriters shall have the right 
to purchase all, but shall not be under any obligation to purchase any, of 
the Notes, and if such non-defaulting Underwriters do not purchase all the 
Notes, this Agreement will terminate without liability to any non-defaulting 
Underwriter or the Company.  In the event of a default by any Underwriter as 
set forth in this Section 11, the Closing Date shall be postponed for such 
period, not exceeding seven days, as you shall determine in order that the 
required changes in the Registration Statement and in the Prospectus or in 
any other documents or arrangements may be effected.  Nothing contained in 
this Agreement shall relieve any defaulting Underwriter of its liability, if 
any, to the Company or any non-defaulting Underwriter for damages occasioned 
by its default hereunder.

         SECTION 12.  NOTICES.  All notices and other communications 
hereunder shall be in writing and shall be deemed to have been duly given if 
mailed or transmitted by any standard form of telecommunication. Notices to 
the Underwriters shall be directed to you c/o NationsBanc Capital Markets, 
Inc., 100 North Tryon Street, Charlotte, North Carolina 28255;  Attention:  
Syndicate; notices to the Company shall be directed to it at Costilla Energy, 
Inc., 400 West Illinois, Suite 1000, Midland, Texas  79701, to the attention 
of the Secretary with copy to the President.

   
         SECTION 13.  PARTIES.  This Agreement shall inure to the benefit of 
and be binding upon the Company, Costilla Energy, L.L.C. (the "LLC"), the 
Underwriters, any controlling persons referred to herein and their respective 
successors and assigns.  The LLC is a party to this Agreement to confirm its 
agreement with the Underwriters that it shall be jointly and severally 
responsible for all obligations of the Company hereunder as an original 
obligor. Nothing expressed or mentioned in this Agreement is intended or 
shall be construed to give any other person, firm or corporation any legal or 
equitable right, remedy or claim under or in respect of this Agreement or any 
provision herein contained. This Agreement and all conditions and provisions 
hereof are intended to be for the sole and exclusive benefit of the parties 
hereto and respective successors and said controlling persons and officers 
and directors and their heirs and legal representatives, and for the benefit 
of no other person, firm or corporation.  No purchaser of Notes from any 
Underwriter shall be deemed to be a successor by reason merely of such 
purchase. 
    

                                    -21- 
<PAGE>

         SECTION 14.  APPLICABLE LAW.  This Agreement will be governed by and 
construed in accordance with the laws of the State of New York.

         SECTION 15.  BUSINESS DAY.  For purposes of this Agreement, 
"business day" means each Monday, Tuesday, Wednesday, Thursday and Friday 
that is not a day on which banking institutions in The City of New York, New 
York are authorized or obligated by law, executive order or regulation to 
close.

         SECTION 16.  COUNTERPARTS.  This Agreement may be executed in one or 
more counterparts, each of which will be deemed to be an original, but all 
such counterparts will together constitute one and the same instrument.
















                                    -22- 
<PAGE>
   
         If the foregoing is in accordance with your understanding of our 
agreement, please sign this Agreement and return a counterpart hereof to us, 
whereupon this instrument, along with all counterparts, will become a binding 
agreement between the Underwriters and the Company in accordance with its 
terms.

                                    Very truly yours,

                                    COSTILLA ENERGY, INC.



                                    By:                                       
                                       -------------------------------------- 
                                       Name:  
                                       Title: 

                                    COSTILLA ENERGY, L.L.C.



                                    By:                                       
                                       -------------------------------------- 
                                       Name:  
                                       Title: 
    

Confirmed and Accepted, as of 
the date first above written: 

NATIONSBANC CAPITAL MARKETS, INC.
PRUDENTIAL SECURITIES INCORPORATED
Acting severally on behalf of 
themselves and the several 
Underwriters named herein. 

By: NATIONSBANC CAPITAL MARKETS, INC.



By:                                       
   -------------------------------------- 
   Name:  
   Title: 

[For themselves and the other
Underwriters named in Schedule I
to the foregoing Agreement]


                                      -23- 
<PAGE>

                                    SCHEDULE I

                                                              PRINCIPAL AMOUNT 
                                                                  OF NOTES
UNDERWRITER                                                    TO BE PURCHASED 
- -----------                                                   ---------------- 
NationsBanc Capital Markets, Inc.. . . . . . . . . . . . . . .    $ 

Prudential Securities Incorporated . . . . . . . . . . . . . .  
                                                                  --------- 
                  Total. . . . . . . . . . . . . . . . . . . .    $         
                                                                  --------- 
                                                                  --------- 













                                    -24- 


<PAGE>







                       COSTILLA ENERGY, INC.,
                             as Issuer,

                Subsidiary Guarantors parties hereto

                            $100,000,000

               ___% SENIOR SUBORDINATED NOTES DUE 2006

                    ____________________________

                              INDENTURE

                    Dated as of ___________, 1996

                STATE STREET BANK AND TRUST COMPANY,

                               Trustee



<PAGE>

                              CROSS-REFERENCE TABLE

         Reconciliation and tie between the Trust Indenture Act of 1939
        as amended, and the Indenture, dated as of ________________, 1996

   TRUST
INDENTURE
    ACT                                                              INDENTURE
  SECTION                                                             SECTION 
- -------------------------------------------------------------------------------
Section 310(a)(1). . . . . . . . . . . . . . . . . . . . . . . . . . . .7.10
         (a)(2). . . . . . . . . . . . . . . . . . . . . . . . . . . . .7.10
         (a)(3). . . . . . . . . . . . . . . . . . . . . . . . . . . . .N.A.
         (a)(4). . . . . . . . . . . . . . . . . . . . . . . . . . . . .N.A.
         (a)(5). . . . . . . . . . . . . . . . . . . . . . . . . . . . .7.10
         (b) . . . . . . . . . . . . . . . . . . . . . . . . . . .7.08; 7.10
         (c) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .N.A.
Section 311(a) . . . . . . . . . . . . . . . . . . . . . . . . . . . . .7.11
         (b) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .7.11
         (c) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .N.A.
Section 312(a) . . . . . . . . . . . . . . . . . . . . . . .7.06(a); 7.06(b)
         (b) . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7.06(c)
         (c) . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7.06(d)
Section 313(a) . . . . . . . . . . . . . . . . . . . . . . . . . . . 7.06(e)
         (b) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .N.A.
         (c) . . . . . . . . . . . . . . . . . . . . . . . .7.06(e); 7.06(f)
         (d) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .7.06
Section 314(a) . . . . . . . . . . . . . . . . . . . . . . . . . .4.17; 4.19
         (b) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .N.A.
         (c)(1). . . . . . . . . . . . . . . . . . . . . . . . . . . . 11.03
         (c)(2). . . . . . . . . . . . . . . . . . . . . . . . . . . . 11.03
         (c)(3). . . . . . . . . . . . . . . . . . . . . . . . . . . . .N.A.
         (d) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .N.A.
         (e) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11.04
         (f) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .4.19
Section 315(a) . . . . . . . . . . . . . . . . . . . . . . . . . . . 7.01(b)
         (b) . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7.05(a)
         (c) . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7.01(a)
         (d) . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7.01(c)
         (e) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .6.10
Section 316(a) . . . . . . . . . . . . . . . . . . . . . . . . . . . . .2.08
         (a)(1)(A) . . . . . . . . . . . . . . . . . . . . . . . . . . .6.05
         (a)(1)(B) . . . . . . . . . . . . . . . . . . . . . . . . . . .6.04
         (a)(2). . . . . . . . . . . . . . . . . . . . . . . . . . . . .N.A.
         (b) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .6.07
         (c) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .9.05
Section 317(a)(1). . . . . . . . . . . . . . . . . . . . . . . . . . . .N.A.
         (a)(2). . . . . . . . . . . . . . . . . . . . . . . . . . . . .6.08
         (b) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .2.04
Section 318(a) . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11.01
         
Note: This reconciliation and tie shall not, for any purpose, be deemed to be
      part of the Indenture.

                                       -i-

<PAGE>

                              TABLE OF CONTENTS
                                                                           Page
                                                                           ----
                                  ARTICLE I        
DEFINITIONS AND OTHER PROVISIONS OF GENERAL APPLICATION. . . . . . . . . . . .1
     SECTION 1.01.    DEFINITIONS. . . . . . . . . . . . . . . . . . . . . .  1
     SECTION 1.02.    INCORPORATION BY REFERENCE OF TRUST INDENTURE ACT. . . 20
     SECTION 1.03.    RULES OF CONSTRUCTION. . . . . . . . . . . . . . . . . 21
     SECTION 1.04.    FORM OF DOCUMENTS DELIVERED TO TRUSTEE . . . . . . . . 21
     SECTION 1.05.    ACTS OF HOLDERS. . . . . . . . . . . . . . . . . . . . 22
     SECTION 1.06.    SATISFACTION AND DISCHARGE . . . . . . . . . . . . . . 22

                                  ARTICLE II
THE NOTES. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23
     SECTION 2.01.    FORM AND DATING. . . . . . . . . . . . . . . . . . . . 23
     SECTION 2.02.    EXECUTION AND AUTHENTICATION . . . . . . . . . . . . . 24
     SECTION 2.03.    REGISTRAR AND PAYING AGENT . . . . . . . . . . . . . . 25
     SECTION 2.04.    PAYING AGENT TO HOLD MONEY IN TRUST. . . . . . . . . . 26
     SECTION 2.05.    GLOBAL NOTES . . . . . . . . . . . . . . . . . . . . . 26
     SECTION 2.06.    TRANSFER AND EXCHANGE. . . . . . . . . . . . . . . . . 27
     SECTION 2.07.    REPLACEMENT NOTES. . . . . . . . . . . . . . . . . . . 28
     SECTION 2.08.    OUTSTANDING NOTES. . . . . . . . . . . . . . . . . . . 29
     SECTION 2.09.    TEMPORARY NOTES. . . . . . . . . . . . . . . . . . . . 30
     SECTION 2.10.    CANCELLATION . . . . . . . . . . . . . . . . . . . . . 30
     SECTION 2.11.    PAYMENT OF INTEREST; INTEREST RIGHTS PRESERVED . . . . 30
     SECTION 2.12.    AUTHORIZED DENOMINATIONS . . . . . . . . . . . . . . . 31
     SECTION 2.13.    COMPUTATION OF INTEREST. . . . . . . . . . . . . . . . 31
     SECTION 2.14.    PERSONS DEEMED OWNERS. . . . . . . . . . . . . . . . . 31
     SECTION 2.15.    CUSIP NUMBERS. . . . . . . . . . . . . . . . . . . . . 31
                                  ARTICLE III
REDEMPTION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 32
     SECTION 3.01.    NOTICE TO TRUSTEE. . . . . . . . . . . . . . . . . . . 32
     SECTION 3.02.    SELECTION OF NOTES TO BE REDEEMED. . . . . . . . . . . 32
     SECTION 3.03.    NOTICE OF REDEMPTION . . . . . . . . . . . . . . . . . 32
     SECTION 3.04.    EFFECT OF NOTICE OF REDEMPTION . . . . . . . . . . . . 33
     SECTION 3.05.    DEPOSIT OF REDEMPTION PRICE. . . . . . . . . . . . . . 33
     SECTION 3.06.    NOTES REDEEMED IN PART . . . . . . . . . . . . . . . . 34
                                  ARTICLE IV
COVENANTS. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 34
     SECTION 4.01.    PAYMENT OF NOTES . . . . . . . . . . . . . . . . . . . 34
     SECTION 4.02.    MAINTENANCE OF OFFICE OR AGENCY. . . . . . . . . . . . 34
     SECTION 4.03.    MONEY FOR THE NOTE PAYMENTS TO BE HELD IN TRUST. . . . 35

                                     -ii-

<PAGE>

     SECTION 4.04.    CORPORATE EXISTENCE. . . . . . . . . . . . . . . . . . 35
     SECTION 4.05.    MAINTENANCE OF PROPERTY. . . . . . . . . . . . . . . . 35
     SECTION 4.06.    PAYMENT OF TAXES AND OTHER CLAIMS. . . . . . . . . . . 36
     SECTION 4.07.    REPURCHASE AT THE OPTION OF HOLDERS UPON A CHANGE OF 
                      CONTROL. . . . . . . . . . . . . . . . . . . . . . . . 36
     SECTION 4.08.    LIMITATION ON ASSET SALES. . . . . . . . . . . . . . . 38
     SECTION 4.09.    OWNERSHIP OF AND LIENS ON CAPITAL STOCK. . . . . . . . 41
     SECTION 4.10.    UNRESTRICTED SUBSIDIARIES. . . . . . . . . . . . . . . 42
     SECTION 4.11.    RESTRICTED PAYMENTS. . . . . . . . . . . . . . . . . . 43
     SECTION 4.12.    INCURRENCE OF INDEBTEDNESS AND ISSUANCE OF PREFERRED 
                      STOCK. . . . . . . . . . . . . . . . . . . . . . . . . 44
     SECTION 4.13.    LIENS. . . . . . . . . . . . . . . . . . . . . . . . . 46
     SECTION 4.14.    DIVIDENDS AND OTHER PAYMENT RESTRICTIONS AFFECTING 
                      SUBSIDIARIES . . . . . . . . . . . . . . . . . . . . . 46
     SECTION 4.15.    LIMITATION ON LAYERING DEBT. . . . . . . . . . . . . . 47
     SECTION 4.16.    TRANSACTIONS WITH AFFILIATES . . . . . . . . . . . . . 47
     SECTION 4.17.    REPORTS. . . . . . . . . . . . . . . . . . . . . . . . 47
     SECTION 4.18.    WAIVER OF STAY, EXTENSION OR USURY LAWS. . . . . . . . 48
     SECTION 4.19.    COMPLIANCE CERTIFICATE; NOTICE OF DEFAULT OR EVENT OF 
                      DEFAULT. . . . . . . . . . . . . . . . . . . . . . . . 48
     SECTION 4.20.    INVESTMENT COMPANY ACT . . . . . . . . . . . . . . . . 48
     SECTION 4.21.    SALE AND LEASEBACK . . . . . . . . . . . . . . . . . . 49
     SECTION 4.22.    FURTHER INSTRUMENTS AND ACTS . . . . . . . . . . . . . 49
                                   ARTICLE V
CONSOLIDATION, MERGER, CONVEYANCE, LEASE OR TRANSFER . . . . . . . . . . . . 49
     SECTION 5.01.    MERGER, CONSOLIDATION OR SALE OF ASSETS. . . . . . . . 49
     SECTION 5.02.    SUCCESSOR CORPORATION SUBSTITUTED. . . . . . . . . . . 50
                                   ARTICLE VI
DEFAULTS AND REMEDIES. . . . . . . . . . . . . . . . . . . . . . . . . . . . 50
     SECTION 6.01.    EVENTS OF DEFAULT. . . . . . . . . . . . . . . . . . . 50
     SECTION 6.02.    ACCELERATION . . . . . . . . . . . . . . . . . . . . . 52
     SECTION 6.03.    OTHER REMEDIES . . . . . . . . . . . . . . . . . . . . 53
     SECTION 6.04.    WAIVER OF PAST DEFAULTS. . . . . . . . . . . . . . . . 53
     SECTION 6.05.    CONTROL BY MAJORITY. . . . . . . . . . . . . . . . . . 53
     SECTION 6.06.    LIMITATION ON SUITS. . . . . . . . . . . . . . . . . . 54
     SECTION 6.07.    RIGHTS OF HOLDERS TO RECEIVE PAYMENT . . . . . . . . . 54
     SECTION 6.08.    TRUSTEE MAY FILE PROOFS OF CLAIM . . . . . . . . . . . 55
     SECTION 6.09.    PRIORITIES . . . . . . . . . . . . . . . . . . . . . . 55
     SECTION 6.10.    UNDERTAKING FOR COSTS. . . . . . . . . . . . . . . . . 56
     SECTION 6.11.    WAIVER OF STAY OR EXTENSION LAWS . . . . . . . . . . . 56
     SECTION 6.12.    TRUSTEE MAY ENFORCE CLAIMS WITHOUT POSSESSION OF THE 
                      NOTES. . . . . . . . . . . . . . . . . . . . . . . . . 56
     SECTION 6.13.    RESTORATION OF RIGHTS AND REMEDIES . . . . . . . . . . 56

                                     -iii-

<PAGE>


     SECTION 6.14.    RIGHTS AND REMEDIES CUMULATIVE . . . . . . . . . . . . 57
     SECTION 6.15.    DELAY OR OMISSION NOT WAIVER . . . . . . . . . . . . . 57
                                  ARTICLE VII
TRUSTEE. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 57
     SECTION 7.01.    DUTIES OF TRUSTEE. . . . . . . . . . . . . . . . . . . 57
     SECTION 7.02.    RIGHTS OF TRUSTEE. . . . . . . . . . . . . . . . . . . 58
     SECTION 7.03.    INDIVIDUAL RIGHTS OF TRUSTEE . . . . . . . . . . . . . 59
     SECTION 7.04.    TRUSTEE'S DISCLAIMER . . . . . . . . . . . . . . . . . 59
     SECTION 7.05.    NOTICE OF DEFAULTS . . . . . . . . . . . . . . . . . . 59
     SECTION 7.06.    PRESERVATION OF INFORMATION; REPORTS BY TRUSTEE TO 
                      HOLDERS. . . . . . . . . . . . . . . . . . . . . . . . 59
     SECTION 7.07.    COMPENSATION AND INDEMNITY . . . . . . . . . . . . . . 60
     SECTION 7.08.    REPLACEMENT OF TRUSTEE . . . . . . . . . . . . . . . . 61
     SECTION 7.09.    SUCCESSOR TRUSTEE BY MERGER. . . . . . . . . . . . . . 63
     SECTION 7.10.    ELIGIBILITY; DISQUALIFICATION. . . . . . . . . . . . . 63
     SECTION 7.11.    PREFERENTIAL COLLECTION OF CLAIMS AGAINST COMPANY. . . 64
                                 ARTICLE VIII
DEFEASANCE . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 64
     SECTION 8.01.    COMPANY'S OPTION TO EFFECT LEGAL DEFEASANCE OR COVENANT
                      DEFEASANCE . . . . . . . . . . . . . . . . . . . . . . 64
     SECTION 8.02.    LEGAL DEFEASANCE AND DISCHARGE . . . . . . . . . . . . 64
     SECTION 8.03.    COVENANT DEFEASANCE. . . . . . . . . . . . . . . . . . 65
     SECTION 8.04.    CONDITIONS TO DEFEASANCE OR COVENANT DEFEASANCE. . . . 66
     SECTION 8.05.    DEPOSITED MONEY AND U.S. GOVERNMENT OBLIGATIONS TO BE 
                      HELD IN TRUST; MISCELLANEOUS PROVISIONS. . . . . . . . 67
     SECTION 8.06.    REINSTATEMENT. . . . . . . . . . . . . . . . . . . . . 68
                                  ARTICLE IX
AMENDMENTS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 68
     SECTION 9.01.    WITHOUT CONSENT OF HOLDERS . . . . . . . . . . . . . . 68
     SECTION 9.02.    WITH CONSENT OF HOLDERS. . . . . . . . . . . . . . . . 69
     SECTION 9.03.    EFFECT OF SUPPLEMENTAL INDENTURES. . . . . . . . . . . 70
     SECTION 9.04.    COMPLIANCE WITH TRUST INDENTURE ACT. . . . . . . . . . 70
     SECTION 9.05.    REVOCATION AND EFFECT OF CONSENTS AND WAIVERS. . . . . 70
     SECTION 9.06.    NOTATION ON OR EXCHANGE OF NOTES . . . . . . . . . . . 71
     SECTION 9.07.    TRUSTEE TO EXECUTE SUPPLEMENTAL INDENTURES . . . . . . 71
     SECTION 9.08.    EFFECT ON SENIOR INDEBTEDNESS. . . . . . . . . . . . . 72
                                   ARTICLE X
SUBORDINATION. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 72
     SECTION 10.01.   AGREEMENT TO SUBORDINATE . . . . . . . . . . . . . . . 72
     SECTION 10.02.   LIQUIDATION; DISSOLUTION; BANKRUPTCY . . . . . . . . . 72
     SECTION 10.03.   DEFAULT ON DESIGNATED SENIOR INDEBTEDNESS. . . . . . . 73
     SECTION 10.04.   ACCELERATION OF NOTES. . . . . . . . . . . . . . . . . 74
     SECTION 10.05.   WHEN DISTRIBUTION MUST BE PAID OVER. . . . . . . . . . 74
     SECTION 10.06.   NOTICE BY COMPANY. . . . . . . . . . . . . . . . . . . 74

                                      -iv-

<PAGE>


     SECTION 10.07.   SUBROGATION. . . . . . . . . . . . . . . . . . . . . . 74
     SECTION 10.08.   RELATIVE RIGHTS. . . . . . . . . . . . . . . . . . . . 75
     SECTION 10.09.   SUBORDINATION MAY NOT BE IMPAIRED BY COMPANY . . . . . 75
     SECTION 10.10.   DISTRIBUTION OR NOTICE TO REPRESENTATIVE . . . . . . . 75
     SECTION 10.11.   RIGHTS OF TRUSTEE AND PAYING AGENT . . . . . . . . . . 76
     SECTION 10.12.   AUTHORIZATION TO EFFECT SUBORDINATION. . . . . . . . . 76
     SECTION 10.13.   AMENDMENTS . . . . . . . . . . . . . . . . . . . . . . 76
                                  ARTICLE XI
SUBSIDIARY GUARANTEES. . . . . . . . . . . . . . . . . . . . . . . . . . . . 76
   
     SECTION 11.01.   ADDITION OF SUBSIDIARY GUARANTORS. . . . . . . . . . . 78
     SECTION 11.02.   RELEASE OF A SUBSIDIARY GUARANTOR. . . . . . . . . . . 79
     SECTION 11.03.   SUBSIDIARY GUARANTORS MAY CONSOLIDATE, ETC., ON CERTAIN
                      TERMS. . . . . . . . . . . . . . . . . . . . . . . . . 77
     SECTION 11.04.   SUBORDINATION OF SUBSIDIARY GUARANTEES . . . . . . . . 80
    
                                  ARTICLE XII
MISCELLANEOUS. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 85
     SECTION 12.01.   TRUST INDENTURE ACT CONTROLS . . . . . . . . . . . . . 85
     SECTION 12.02.   NOTICES. . . . . . . . . . . . . . . . . . . . . . . . 85
     SECTION 12.03.   CERTIFICATE AND OPINION AS TO CONDITIONS PRECEDENT . . 85
     SECTION 12.04.   STATEMENTS REQUIRED IN CERTIFICATE OR OPINION. . . . . 86
     SECTION 12.05.   RULES BY TRUSTEE, PAYING AGENT AND REGISTRAR . . . . . 86
     SECTION 12.06.   PAYMENTS ON BUSINESS DAYS. . . . . . . . . . . . . . . 86
     SECTION 12.07.   GOVERNING LAW. . . . . . . . . . . . . . . . . . . . . 86
     SECTION 12.08.   NO RECOURSE AGAINST OTHERS . . . . . . . . . . . . . . 86
     SECTION 12.09.   SUCCESSORS . . . . . . . . . . . . . . . . . . . . . . 86

                                      -v-

<PAGE>

     SECTION 12.10.   COUNTERPARTS . . . . . . . . . . . . . . . . . . . . . 87
     SECTION 12.11.   TABLE OF CONTENTS; HEADINGS. . . . . . . . . . . . . . 87
     SECTION 12.12.   SEVERABILITY . . . . . . . . . . . . . . . . . . . . . 87
     SECTION 12.13.   FURTHER INSTRUMENTS AND ACTS . . . . . . . . . . . . . 87

EXHIBIT A    FORM OF GLOBAL NOTE
EXHIBIT B    FORM OF CERTIFICATED NOTE
   
EXHIBIT C    FORM OF SUBSIDIARY GUARANTEE
    

                                     -vi-


<PAGE>

   
     INDENTURE, dated as of _______________, 1996, between COSTILLA ENERGY, 
INC., a Delaware corporation (the "Company"), having its principal office at 
400 West Illinois, Suite 1000, Midland, Texas 79701, and STATE STREET BANK 
AND TRUST COMPANY, a Massachusetts trust company, as trustee hereunder (the 
"Trustee"), having its Corporate Trust Office at Two International Place, 
Corporate Trust Department, 4th Floor, Boston, Massachusetts 02110.
    

                           RECITALS OF THE COMPANY

     The Company has duly authorized the creation and issue of its ____% 
Senior Subordinated Notes Due 2006 (the "Notes") of substantially the tenor 
and amount hereinafter set forth, and to provide therefor, the Company has 
duly authorized the execution and delivery of this Indenture.

   
    

   
     All things necessary to make the Notes, when executed by the Company and 
authenticated by the Trustee and delivered hereunder and duly issued by the 
Company, the valid obligations of the Company and to make this Indenture a 
valid instrument of the Company, in accordance with their respective terms, 
have been done.
    

     NOW, THEREFORE, THIS INDENTURE WITNESSETH, that, for and in 
consideration of the premises and the purchase of the Notes by the Holders 
thereof, it is mutually covenanted and agreed, for the equal and 
proportionate benefit of all Holders of the Notes, as follows:

                                 ARTICLE I

          DEFINITIONS AND OTHER PROVISIONS OF GENERAL APPLICATION

     SECTION 1.01.  DEFINITIONS.  For all purposes of this Indenture, except 
as otherwise expressly provided or unless the context otherwise requires:

         (a)  the terms defined in this Article have the meanings assigned 
     to them in this Article, and include the plural as well as the singular; 
     and

         (b)  all accounting terms not otherwise defined herein have the 
     meanings assigned to them in accordance with GAAP.


                                     -1-

<PAGE>

     "ACQUIRED INDEBTEDNESS" means, with respect to any specified Person, (i) 
any Indebtedness of any other Person existing at the time such other Person 
is merged with or into or becomes a Subsidiary of such specified Person, 
including, without limitation, Indebtedness incurred in connection with, or 
in contemplation of, such other Person merging with or into or becoming a 
Subsidiary of such specified Person, and (ii) Indebtedness secured by a Lien 
encumbering any asset acquired by such specified Person.

     "ACT" when used with respect to any Holder, has the meaning set forth in 
Section 1.05 hereof.

     "ADJUSTED CONSOLIDATED NET TANGIBLE ASSETS" means, as of the date of 
determination, without duplication, (a) the sum of (i) discounted future net 
revenue from proved oil and gas reserves of the Company and its Subsidiaries 
calculated in accordance with Commission guidelines before any state or 
federal income taxes, as estimated in a reserve report prepared as of the end 
of the Company's most recently completed fiscal year, which reserve report is 
prepared or audited by independent petroleum engineers, as increased by, as 
of the date of determination, the discounted future net revenue of (A) 
estimated proved oil and gas reserves of the Company and its Subsidiaries 
attributable to any acquisition consummated since the date of such year-end 
reserve report, and (B) estimated oil and gas reserves of the Company and its 
Subsidiary attributable to extensions, discoveries and other additions and 
upward revisions of estimates of proved oil and gas reserves due to 
exploration, development, exploitation, production or other activities 
conducted or otherwise occurring since the date of such year-end reserve 
report which would, in the case of determinations made pursuant to clauses 
(A) and (B), in accordance with standard industry practice, result in such 
additions or revisions, in each case calculated in accordance with Commission 
guidelines (utilizing the prices utilized in such year-end reserve report), 
and decreased by, as of the date of determination, the discounted future net 
revenue of (C) estimated proved oil and gas reserves of the Company and its 
Subsidiaries produced or disposed of since the date of such year-end reserve 
report and (D) reductions in the estimated oil and gas reserves of the 
Company and its Subsidiaries since the date of such year-end reserve report 
attributable to downward revisions of estimates of proved oil and gas 
reserves due to exploration, development, exploitation, production or other 
activities conducted or otherwise occurring since the date of such year-end 
reserve report which would, in the case of determinations made pursuant to 
clauses (C) and (D), in accordance with standard industry practice, result in 
such revisions, in each case calculated in accordance with Commission 
guidelines (utilizing the prices utilized in such year-end reserve report); 
provided that, in the case of each of the determinations made pursuant to 
clauses (A) through (D), such increases and decreases shall be as estimated 
by the Company's engineers, except that if as a result of such acquisitions, 
dispositions, discoveries, extensions or revisions, there is a Material 
Change that is an increase, then such increases and decreases in the 
discounted future net revenue shall be confirmed in writing by independent 
petroleum engineers, (ii) the capitalized costs that are attributable to oil 
and gas properties of the Company and its Subsidiaries to which no proved oil 
and gas reserves are attributed, based on the Company's books and records as 
of a date no earlier than the date of the Company's latest annual or 
quarterly financial statements, (iii) the net working capital (which shall be 
calculated as all current assets of the Company and its  Subsidiaries minus 
all current liabilities of the Company and its  Subsidiaries, except current 
liabilities included in Indebtedness on a date no earlier than the date of 


                                     -2-

<PAGE>

the Company's latest annual or quarterly financial statements) and (iv) the 
greater of (I) the net book value of the other tangible assets of the Company 
and its  Subsidiaries on a date no earlier than the date of the Company's 
latest annual or quarterly financial statements and (II) the appraised value, 
as estimated by independent appraisers, of other tangible assets of the 
Company and its  Subsidiaries as of a date no earlier than the date of the 
Company's latest audited financial statements, minus (b) the sum of (i) 
minority interests of third parties to the extent included in the calculation 
of the immediately preceding clause (a), (ii) the positive remainder, if any, 
obtained by subtracting (I) gas balancing underpayments of the Company and 
its  Subsidiaries reflected in the Company's latest audited financial 
statements and not otherwise included in the calculation of the immediately 
preceding clause (a) from (II) any gas balancing liabilities of the Company 
and its  Subsidiaries reflected in the Company's latest audited financial 
statements and not otherwise included in the calculation of the immediately 
preceding clause (a), and  (iii) the discounted future net revenue, 
calculated in accordance with Commission guidelines (utilizing the same 
prices utilized in the Company's year-end reserve report), attributable to 
oil and gas reserves of the Company and its Subsidiaries subject to 
participation interests, overriding royalty interests or other interests of 
third parties, pursuant to participation, partnership, vendor financing or 
other agreements then in effect other than pursuant to Production Payments, 
or that otherwise are required to be delivered to third parties other than 
pursuant to Production Payments.

     "ADJUSTED CONSOLIDATED NET TANGIBLE ASSETS TO CONSOLIDATED INDEBTEDNESS 
RATIO" means, at any time, the ratio of Adjusted Consolidated Net Tangible 
Assets at such time, to Consolidated Indebtedness at such time.

     "ADJUSTED NET ASSETS" of a Subsidiary Guarantor at any date shall mean 
the amount by which the fair value of the property of such Subsidiary 
Guarantor exceeds the total amount of liabilities of such Subsidiary 
Guarantor, including, without limitation, contingent liabilities (after 
giving effect to all other fixed and contingent liabilities incurred or 
assumed on such date), but excluding liabilities under such Subsidiary 
Guarantor's Subsidiary Guarantee at such date.

     "AFFILIATE" of any specified Person means (i) any other Person directly 
or indirectly controlling or controlled by or under direct or indirect common 
control with such specified Person or (ii) any other Person who is a director 
or executive officer of (a) such specified Person or (b) any Person described 
in the preceding clause (i).  For purposes of this definition, "control" 
(including, with correlative meanings, the terms "controlling," "controlled 
by" and "under common control with"), as used with respect to any Person, 
shall mean the possession, directly or indirectly, of the power to direct or 
cause the direction of the management or policies of such Person, whether 
through the ownership of voting securities, by agreement or otherwise; 
provided that beneficial ownership of 10% or more of any class, or any series 
of any class, of equity securities of a Person, whether or not voting, shall 
be deemed to be control.

     "AFFILIATE TRANSACTION" has the meaning set forth in Section 4.16 hereof.

     "AGENT MEMBER" has the meaning set forth in Section 2.05(a) hereof.


                                     -3-

<PAGE>

     "APPROVED STOCKHOLDERS" means Cadell S. Liedtke, Michael J. Grella and 
Henry G. Musselman and their respective Beneficiaries.

   
     "ASSET SALE" means with respect to any Person, the sale, lease, 
conveyance or other disposition, that does not constitute a Restricted 
Payment or an Investment, by such Person of any of its assets (including, 
without limitation, by way of a Sale and Leaseback Transaction and including 
the issuance, sale or other transfer of any Equity Interests in any 
Subsidiary or the sale or other transfer of any Equity Interests in any 
Unrestricted Subsidiary of such Person) other than to the Company (including 
the receipt of proceeds of insurance paid on account of the loss of or damage 
to any asset and awards of compensation for any asset taken by condemnation, 
eminent domain or similar proceeding, and including the receipt of proceeds 
of business interruption insurance), in each case, in one or a series of 
related transactions; PROVIDED that, notwithstanding the foregoing, the term 
"Asset Sale" shall not include: (a) the sale, lease, conveyance, disposition 
or other transfer of all or substantially all of the assets of the Company, 
as permitted pursuant to Article V, (b) the sale or lease of hydrocarbons or 
other mineral interests in the ordinary course of business and customary in 
the Oil and Gas Business, (c) any Production Payment, (d) a transfer of 
assets by the Company to a Wholly Owned Subsidiary of the Company (other than 
any Principal Properties) or by a Wholly Owned Subsidiary of the Company to 
the Company or to another Wholly Owned Subsidiary of the Company, (e) an 
issuance of Equity Interests by a Wholly Owned Subsidiary of the Company to 
the Company or to another Wholly Owned Subsidiary of the Company, (f) sale or 
other disposition of cash or Cash Equivalents or (g) any lease, abandonment, 
disposition, relinquishment or farm out of any oil and gas property that are 
customary in nature and scope in the Oil and Gas Business and are entered into 
in the ordinary course of the Oil and Gas Business of the Company and its 
Subsidiaries.

     "ASSET SALE OFFER" has the meaning set forth in Section 4.08(d) hereof.

     "ASSET SALE PAYMENT DATE" has the meaning set forth in Section 
4.08(e)(ii) hereof.

     "ASSET SALE PURCHASE PRICE" has the meaning set forth in Section 4.08(d) 
hereof
    

     "BENEFICIARY" when used with respect to any individual, means the 
spouse, lineal descendants, parents and siblings of any such individual, the 
estates and the legal representatives of any such individual and any of the 
foregoing and the trustee of any bona fide trust of which any such individual 
and any of the foregoing are the sole beneficiaries or grantors.

     "BOARD OF DIRECTORS" means, with respect to any Person,  the Board of 
Directors of such Person or any committee thereof duty authorized to act on 
behalf of such Board.

     "BOARD RESOLUTION" means, with respect to any Person, a duly adopted 
resolution of the Board of Directors in full force and effect at the time of 
determination and certified as such by the Secretary or an Assistant 
Secretary of such Person.


                                     -4-


<PAGE>

     "BUSINESS DAY" means each Monday, Tuesday, Wednesday, Thursday and 
Friday that is not a day on which banking institutions in The City of New 
York are authorized or obligated by law, executive order or regulation to 
close.

     "CAPITAL LEASE OBLIGATION" means, at the time any determination thereof 
is to be made, the amount of the liability in respect of a capital lease 
which would at such time be required to be capitalized on a balance sheet in 
accordance with GAAP.

     "CAPITAL STOCK" means (i) in the case of a corporation, capital stock, 
(ii) in the case of an association or business entity, any and all shares, 
interests, participations, rights or other equivalents (however designated) 
of capital stock, (iii) in the case of a partnership, partnership interests 
(whether general or limited) and (iv) any other interest or participation 
that confers on a Person the right to receive a share of the profits and 
losses of, or distributions of assets of, the issuing Person.

     "CASH EQUIVALENT" means (a) securities issued or directly and fully 
guaranteed or insured by the United States of America or any agency or 
instrumentality thereof (provided that the full faith and credit of the 
United States is pledged in support thereof) having maturities not more than 
twelve months from the date of acquisition, (b) U.S. dollar denominated (or 
foreign currency fully hedged) time deposits, certificates of deposit, 
Eurodollar time deposits or Eurodollar certificates of deposit of (i) any 
domestic commercial bank of recognized standing having capital and surplus in 
excess of $500 million or (ii) any bank whose short-term commercial  paper 
rating from S&P is at least A-1 or the equivalent thereof or from Moody's is 
at least P-1 or the equivalent thereof (any such bank being an "Approved 
Lender"), in each case with maturities of not more than twelve months from 
the date of acquisition, and (c) commercial paper issued by any Approved 
Lender (or by the parent company thereof) or any variable rate notes issued 
by, or guaranteed by, any domestic corporation rated A-1 (or the equivalent 
thereof) or better by S&P or P-1 (or the equivalent thereof) or better by 
Moody's and maturing within twelve months of the date of acquisition.

     "CERTIFICATED NOTES" means Notes issued in definitive, fully registered 
form to beneficial owners of interests in the Global Note pursuant to Section 
2.06(a) hereof.

     "CHANGE OF CONTROL" means 

          (i)  any "person" or "group" (as such terms are used in Sections 
     13(d) and 14(d) of the Exchange Act) other than the Approved 
     Stockholders, is or becomes the "beneficial owner" (as defined in Rule 
     13d-3 under the Exchange Act), directly or indirectly, of more than 50% 
     of the total Voting Stock of the Company; or

         (ii)    the Company is merged with or into or consolidated with 
     another Person and, immediately after giving effect to the merger or 
     consolidation, (A) less than 50% of the total voting power of the 
     outstanding Voting Stock of the surviving or resulting Person is then 
     "beneficially owned" (within the meaning of Rule 13d-3 under the 
     Exchange Act) in the aggregate by the stockholders of the Company 
     immediately prior to such merger or consolidation, and (B) 


                                     -5-

<PAGE>

     any "person" or "group" (as defined in Section 13(d)(3) or 14(d)(2) of 
     the Exchange Act) other than the Approved Stockholders, has become the 
     direct or indirect "beneficial owner" (as defined in Rule 13d-3 under 
     the Exchange Act) of more than 50% of the total voting power of the 
     Voting Stock of the surviving or resulting Person; or

          (iii)   the Company, either individually or in conjunction with one 
     or more Subsidiaries, sells, assigns, conveys, transfers, leases or 
     otherwise disposes of, or the Subsidiaries sell, assign, convey, 
     transfer, lease or otherwise dispose of, all or substantially of the 
     properties of the Company and the Subsidiaries, taken as a whole (either 
     in one transaction or a series of related transactions) including 
     Capital Stock of the Subsidiaries, to any Person (other than the Company 
     or a Wholly Owned Subsidiary); or

          (iv)    during any consecutive two-year period, individuals who at 
     the beginning of such period constituted the Board of Directors of the 
     Company (together with any new directors whose election by such Board of 
     Directors or whose nomination for election by the stockholders of the 
     Company was approved by a vote of a majority of the directors then still 
     in office who were either directors at the beginning of such period or 
     whose election or nomination for election was previously so approved) 
     cease for any reason to constitute a majority of the Board of Directors 
     of the Company then in office; or

          (v)   the liquidation or dissolution of the Company.

     "CHANGE OF CONTROL OFFER" has the meaning set forth in Section 4.07(a) 
hereof.

     "CHANGE OF CONTROL PAYMENT DATE" has the meaning set forth in Section 
4.07(a) hereof.

     "CHANGE OF CONTROL PURCHASE PRICE" has the meaning set forth in Section 
4.07(a) hereof.

     "CLEARING AGENCY" has the meaning set forth in Section 3(a)(23) of the 
Exchange Act.

     "CODE" means the Internal Revenue Code of 1986, as amended.

     "COMMISSION" means the United States Securities and Exchange Commission, 
as from time to time constituted, created under the Exchange Act, or, if at 
any time after the execution of this Indenture such commission is not 
existing and performing the duties now assigned to it under the Trust 
Indenture Act, the body performing such duties at such time.

     "COMPANY" means the party named as such in the preamble to this 
Indenture until a successor replaces it pursuant to the applicable provisions 
hereof and, thereafter, means such successor.

     "COMPANY ORDER" means a written order signed in the name of the Company 
by (i) its Chairman of the Board, President, a Vice Chairman or a Vice 
President, and (ii) its Treasurer, an Assistant Treasurer, its Secretary or 
an Assistant Secretary.


                                     -6-

<PAGE>

     CONSOLIDATED EBITDA means, with respect to any Person for any period, 
the sum of, without duplication, (i) the Consolidated Net Income of such 
Person and its Subsidiaries for such period, plus (ii) to the extent deducted 
in the computation of such Consolidated Net Income, the Consolidated Interest 
Expense for such period, plus (iii) to the extent deducted in the computation 
of such Consolidated Net Income, amortization of deferred financing charges 
for such period, plus (iv) provision for taxes based on income or profits for 
such period (to the extent such income or profits were included in computing 
Consolidated Net Income for such period), plus (v) to the extent deducted in 
the computation of such Consolidated Net Income, consolidated depreciation, 
depletion, amortization and other noncash charges of such Person and its 
Subsidiaries required to be reflected as expenses on the books and records of 
such Person, plus (vi) to the extent deducted in the computation of such 
Consolidated Net Income, consolidated exploration and abandonment expenses of 
such Person and its Subsidiaries for such periods, minus (vii) cash payments 
with respect to any nonrecurring, noncash charges previously added back 
pursuant to clause (v), and excluding (viii) the impact of foreign currency 
translations.  Notwithstanding the foregoing, the provision for taxes based 
on the income or profits of, and the depreciation, depletion and amortization 
and other noncash charges of, and the exploration and abandonment expenses 
of, a Subsidiary of a Person shall be added to Consolidated Net Income to 
compute Consolidated EBITDA only to the extent (and in the same proportion) 
that the Net Income of such Subsidiary was included in calculating the 
Consolidated Net Income of such Person and only if a corresponding amount 
would be permitted at the date of determination to be dividended to such 
Person by such Subsidiary without prior approval (unless such approval has 
been obtained), pursuant to the terms of its charter and all agreements, 
instruments, judgments, decrees, orders, statutes, rules and governmental 
regulations applicable to that Subsidiary or its stockholders.

     "CONSOLIDATED INDEBTEDNESS" means, with respect to any Person for any 
time, the Indebtedness of such Person and its Subsidiaries at such time as 
determined on a consolidated basis in accordance with GAAP.

     "CONSOLIDATED INTEREST COVERAGE RATIO" means with respect to any Person 
for any period, the ratio of (i) Consolidated EBITDA of such Person and its 
Subsidiaries for such period to (ii) Consolidated Interest Expense of such 
Person and its Subsidiaries for such period.  In the event that the Company 
or any of its Subsidiaries incurs, assumes, Guarantees or repays or redeems 
any Indebtedness (other than revolving credit borrowings) or issues or 
redeems preferred stock subsequent to the commencement of the four-quarter 
reference period for which the Consolidated Interest Coverage Ratio is being 
calculated but on or prior to the date on which the event for which the 
calculation of the Consolidated Interest Coverage Ratio is made (the 
"Calculation Date"), then the Consolidated Interest Coverage Ratio shall be 
calculated giving pro forma effect to such incurrence, assumption, Guarantee, 
repayment or redemption of Indebtedness, or such issuance or redemption of 
preferred stock, as if the same had occurred at the beginning of the 
applicable four-quarter reference period.  For purposes of making the 
computation referred to above, (i) acquisitions that have been made by the 
Company or any of its Subsidiaries, including through mergers or 
consolidations and including any related financing transactions, during the 
four-quarter reference period or subsequent to such reference period and on 
or prior to the Calculation Date shall be deemed 


                                     -7-

<PAGE>


to have occurred on the first day of the four-quarter reference period, and 
(ii) the Consolidated EBITDA attributable to discontinued operations, as 
determined in accordance with GAAP, and operations or businesses disposed of 
prior to the Calculation Date, shall be excluded, and (iii) the Consolidated 
Interest Expense attributable to discontinued operations, as determined in 
accordance with GAAP, and operations or businesses disposed of prior to the 
Calculation Date, shall be excluded, but only to the extent that the 
obligations giving rise to such Consolidated Interest Expense will not be 
obligations of the referent Person or any of its Subsidiaries following the 
Calculation Date.
   
     "CONSOLIDATED INTEREST EXPENSE" means, with respect to any Person for 
any period, the sum, without duplication, of (i) the consolidated interest 
expense of such Person and its Subsidiaries for such period including, 
without limitation, amortization of original issue discount, noncash interest 
payments, the interest component of any deferred payment obligations, the 
interest component of all payments associated with Capital Lease Obligations, 
commissions, discounts and other fees and charges incurred in respect of 
letter of credit or bankers' acceptance financings, and net payments (if any) 
pursuant to Hedging Obligations, but excluding amortization or write-off of 
deferred financing charges for such period, and (ii) the consolidated interest 
expense of such Person and its Subsidiaries that was capitalized during such 
period, and (iii) any interest expense on Indebtedness of another Person that 
is Guaranteed by such Person or one of its Subsidiaries or secured by a Lien 
on assets of such Person or one of its Subsidiaries (whether or not such 
Guarantee or Lien is called upon), and (iv) the product of (a) all cash 
dividend payments (and noncash dividend payments in the case of a Person that 
is a Subsidiary) on any series of preferred stock of such Person payable to a 
party other than the Company or a Wholly Owned Subsidiary, times (b) a 
fraction, the numerator of which is one and the denominator of which is one 
minus the then current combined federal, state and local statutory tax rate 
of such Person, expressed as a decimal, on a consolidated basis and in 
accordance with GAAP.
    
     "CONSOLIDATED NET INCOME" means, with respect to any Person for any 
period, the aggregate of the Net Income of such Person and its Subsidiaries 
for such period, on a consolidated basis, determined in accordance with GAAP; 
PROVIDED that (i) the Net Income (but not loss) of any Person that is not a 
Subsidiary or that is accounted for by the equity method of accounting shall 
be included only to the extent of the amount of dividends or distributions 
paid in cash to the referent Person or a Wholly Owned Subsidiary thereof, 
(ii) the Net Income of any Subsidiary shall be excluded to the extent that 
the declaration or payment of dividends or similar distributions by that 
Subsidiary of that Net Income is not at the date of determination permitted 
without any prior governmental approval (unless such approval has been 
obtained) or, directly or indirectly, by operation of the terms of its 
charter or any agreement, instrument, judgment, decree, order, statute, rule 
or governmental regulation applicable to that Subsidiary or its stockholders, 
(iii) the Net Income of any Person acquired in a pooling of interests 
transaction for any period prior to the date of such acquisition shall be 
excluded, (iv) the cumulative effect of a change in accounting principles 
shall be excluded, and (v) the Net Income of, or any dividends or other 
distributions from, any Unrestricted Subsidiary, to the extent otherwise 
included, shall be excluded, unless distributed to the Company or one of its 
Subsidiaries.


                                     -8-

<PAGE>

     "CONSOLIDATED NET WORTH" means, with respect to any Person as of any 
date, the consolidated stockholders' equity of such Person and its 
consolidated Subsidiaries as of such date less (w) the amount of such 
stockholders' equity attributable to Disqualified Stock, (x) all write-ups 
subsequent to the date of this Indenture in the book value of any asset owned 
by such Person or a consolidated Subsidiary of such Person (other than 
purchase accounting adjustments made, in connection with any acquisition of 
any entity that becomes a consolidated Subsidiary of such Person after the 
date of this Indenture to the book value of the assets of such entity), (y) 
all investments as of such date in unconsolidated Subsidiaries and in Persons 
that are not Subsidiaries (except, in each case, Permitted Investments), and 
(z) all unamortized debt discount and expense and unamortized deferred charges
as of such date, all of the foregoing determined in accordance with GAAP.

     "CORPORATE TRUST OFFICE" means the principal office of the Trustee at 
which at any particular time its corporate trust business shall be principally
administered, which office is, at the date of execution of this Indenture, 
located at Two International Place, Corporate Trust Department, 4th Floor, 
Boston, Massachusetts 02110.

     "COVENANT DEFEASANCE" has the meaning set forth in Section 8.03 hereof.

   
     "CREDIT FACILITY" means a credit facility that may be entered into among 
the Company and the lenders parties thereto (which shall initially be a 
credit facility among the Company, Nations-Bank of Texas, N.A. or one of its 
affiliates, as agent, and the other lenders parties thereto), including any 
related notes, guarantees, collateral documents, instruments and agreements 
executed in connection therewith, and in each case as amended, modified, 
renewed, extended, refunded, replaced, restated or refinanced from time to 
time.
    

     "DEFAULT" means any event that is or with the passage of time or the giving
of notice or both would be an Event of Default.

     "DEFAULTED INTEREST" has the meaning set forth in Section 2.11 hereof.

     "DEPOSITARY" means The Depository Trust Company, its nominees, and their 
respective successors.

     "DESIGNATED GUARANTOR SENIOR INDEBTEDNESS" means (i) so long as the Senior
Bank Indebtedness is outstanding, any Subsidiary Guarantor's Indebtedness in 
respect of the Senior Bank Indebtedness and (ii) thereafter, any other Guarantor
Senior Indebtedness permitted under this Indenture the principal amount of which
is $15.0 million or more and that has been designated by the Company as 
"Designated Guarantor Senior Indebtedness"; PROVIDED that for purposes of 
Section 11.10(a) hereof, "Designated Guarantor Senior Indebtedness" shall also 
mean any other Guarantor Senior Indebtedness permitted under this Indenture the
principal amount of which is $15.0 million or more.

     "DESIGNATED SENIOR INDEBTEDNESS" means (i) so long as the Senior Bank 
Indebtedness is outstanding, the Senior Bank Indebtedness and (ii) thereafter,
any other Senior Indebtedness 




                                    -9-


<PAGE>

permitted under this Indenture the principal amount of which is $15.0 million 
or more and that has been designated by the Company as "Designated Senior 
Indebtedness"; PROVIDED that for purposes of Section 10.03(a) hereof, 
"Designated Senior Indebtedness" shall also mean any other Senior 
Indebtedness permitted under this Indenture the principal amount of which is 
$15.0 million or more.

     "DISQUALIFIED STOCK" means (a) with respect to any Person, Capital Stock 
of such Person that, by its terms (or by the terms of any security into which 
it is convertible or for which it is exchangeable), or upon the happening of 
any event (unless any redemption or repurchase of such Capital Stock upon the 
occurrence of such event is required by any such terms, but only to the extent
that a payment in respect thereof would be permitted under Section 4.11 hereof),
matures or is mandatorily redeemable, pursuant to a sinking fund obligation or
otherwise, or is redeemable at the option of the Holder thereof, in whole or 
in part, on or prior to the date which is one year after the date on which the
Notes mature and (b) with respect to any Subsidiary of such Person (including 
with respect to any Subsidiary of the Company), any Capital Stock other than 
any common stock with no preference, privileges, or redemption or repayment 
provisions.

     "DOLLAR-DENOMINATED PRODUCTION PAYMENTS" means dollar denominated 
payment obligations of the Company or any of its Subsidiaries that are or, 
upon the occurrence of a contingent event, would be recorded as liabilities 
in accordance with GAAP, together with all undertakings and obligations of 
the Company or any of its Subsidiaries in connection therewith, which 
obligations will be deemed to constitute Indebtedness for borrowed money for 
purposes of this Indenture.

     "EQUITY INTERESTS" means Capital Stock and all warrants, options or other
rights to acquire Capital Stock (but excluding any debt security that is 
convertible into, or exchangeable for, Capital Stock), whether outstanding 
prior to, on or after the date of this Indenture.

     "EQUITY OFFERING" means an offer and sale of Qualified Stock of the Company
to a Person other than an Affiliate of the Company.

     "EVENT OF DEFAULT" has the meaning set forth in Section 6.01 hereof.

   
     "EXCESS PROCEEDS" has the meaning set forth in Section 4.08(c) hereof.
    

     "EXCHANGE ACT" means the Securities Exchange Act of 1934, as amended, and
the rules and regulations promulgated thereunder.

     "EXEMPT AFFILIATE TRANSACTIONS" means (a) transactions between or among 
the Company and/or its Wholly Owned Subsidiaries, (b) advances not to exceed 
$1,000,000 at any time outstanding to officers of the Company or any Subsidiary
of the Company in the ordinary course of business to provide for the payment 
of reasonable expenses incurred by such persons in the performance of their 
responsibilities to the Company or such Subsidiary or in connection with any
relocation, (c) fees and compensation paid to and indemnity provided on behalf
of directors, officers or employees of the Company or any Subsidiary of the 
Company in the ordinary course of business, (d) any employment 




                                   -10-


<PAGE>

agreement that is in effect on the date of the Indenture in the ordinary 
course of business and any such agreement entered into by the Company or a 
Subsidiary after the date of this Indenture in the ordinary course of 
business of the Company or such Subsidiary and (e) payments and transactions 
under Indebtedness of A&P Meter Service and Supply, Inc. ("A&P") 
outstanding on the date of this Indenture and performance of and payment for 
services provided by A&P to the Company and its Subsidiaries in the ordinary 
course of business consistent with past practices.

   
     "FUNDING GUARANTOR" has the meaning specified in Section 3 of the 
Subsidiary Guarantees.
    

     "GAAP" means generally accepted accounting principles set forth in the 
opinions and pronouncements of the Accounting Principles Board of American 
Institute of Certified Public Accountants and statements and pronouncements 
of the Financial Accounting Standards Board or in such other statements by 
such other entity as have been approved by a significant segment of the 
accounting profession, which are in effect on the date of this Indenture.

     "GLOBAL NOTES" has the meaning set forth in Section 2.01(c) hereof.

     "GUARANTEE" means a guarantee (other than by endorsement of negotiable 
instruments for collection in the ordinary course of business), direct or 
indirect, in any manner (including, without limitation, letters of credit and 
reimbursement agreements in respect thereof), of all or any part of any 
Indebtedness.

     "GUARANTOR SENIOR INDEBTEDNESS" means (i) all Guarantees or other 
Indebtedness of a Subsidiary Guarantor in respect of the Senior Bank 
Indebtedness and (ii) any other indebtedness permitted to be incurred by a 
Subsidiary Guarantor under the terms of this Indenture, unless the instrument 
under which such Indebtedness is incurred expressly provides that it is 
subordinated in right of payment to any Indebtedness for money borrowed.  
Notwithstanding anything to the contrary in the foregoing, Guarantor Senior 
Indebtedness will not include (w) any liability for federal, state, local or 
other taxes owed or owing by a Subsidiary Guarantor, (x) any Indebtedness of 
a Subsidiary Guarantor to any of the Company's  Subsidiaries, Unrestricted 
Subsidiaries or other Affiliates, (y) any trade payables or (z) any 
Indebtedness that is incurred in violation of this Indenture.

     "HEDGING OBLIGATIONS" means, with respect to any Person, the obligations 
of such Person under (i) interest rate swap agreements, interest rate cap 
agreements and interest rate collar agreements and (ii) other agreements or 
arrangements designed to protect such Person against fluctuations in (a) 
interest rates, (b) the value of foreign currencies and (c) Oil and Gas 
Purchase and Sales Contracts.

     "HOLDER" means (i) in the case of any Certificated Note, the Person in 
whose name such Certificated Note is registered in the Security Register and 
(ii) in the case of any Global Note, the Depositary.

     "INDEBTEDNESS" means, with respect to any Person, without duplication, 
(a) all liabilities of such Person for borrowed money or for the deferred 
purchase price of property or services (excluding 




                                   -11-


<PAGE>

any trade accounts payable and other accrued current liabilities incurred in 
the ordinary course of business), and all liabilities of such Person incurred 
in connection with any letters of credit, bankers' acceptances or other 
similar credit transactions or any agreement to purchase, redeem, exchange, 
convert or otherwise acquire for value any Capital Stock of such Person, or 
any warrants, rights or options to acquire such Capital Stock outstanding on 
the date of this Indenture or thereafter, if, and to the extent, any of the 
foregoing would appear as a liability upon a balance sheet of such Person 
prepared in accordance with GAAP, (b) all obligations of such Person 
evidenced by bonds, notes, debentures or other similar instruments, if, and 
to the extent, any of the foregoing would appear as a liability upon a 
balance sheet of such Person prepared in accordance with GAAP, (c) all 
Indebtedness of such Person created or arising under any conditional sale or 
other title retention agreement with respect to property acquired by such 
Person (even if the rights and remedies of the seller or lender under such 
agreement in the event of default are limited to repossession or sale of such 
property), but excluding trade accounts payable arising in the ordinary 
course of business, (d) all Capitalized Lease Obligations of such Person, (e) 
all Indebtedness referred to in the preceding clauses of other Persons and 
all dividends of other Persons, the payment of which is secured by (or for 
which the holder of such Indebtedness has an existing right to be secured by) 
any Lien upon property (including, without limitation, accounts and contract 
rights) owned by such Person, even though such Person has not assumed or 
become liable for the payment of such Indebtedness (the amount of such 
obligation being deemed to be the lesser of the value of such property or 
asset or the amount of the obligation so secured) (f) all Production Payments 
of such Person, (g) all guarantees by such Person of Indebtedness referred to 
in this definition, (h) all Disqualified Stock of such Person valued at the 
greater of its voluntary or involuntary maximum fixed repurchase price plus 
accrued dividends and (i) all obligations of such Person under or in respect 
to currency exchange contracts, oil or natural gas price hedging arrangements 
and Hedging Obligations.  For purposes hereof, the "maximum fixed repurchase 
price" of Disqualified Stock which does not have a fixed repurchase price 
shall be calculated in accordance with the terms of such Disqualified Stock 
as if Disqualified Stock were purchased on any date on which Indebtedness 
shall be required to be determined pursuant to this Indenture, and if such 
price is based upon, or measured by, the fair market value of such 
Disqualified Stock, such fair market value shall be determined in good faith 
by the board of directors of the issuer of such Disqualified Stock; provided, 
however, that if such Disqualified Stock is not at the date of determination 
permitted or required to be repurchased, the "maximum fixed repurchase price" 
shall be the book value of such Disqualified Stock.  

     "INDENTURE" means this instrument as originally executed or as it may from
time to time be supplemented or amended by one or more indentures supplemental 
hereto entered into pursuant to the applicable provisions hereof, including, 
for all purposes of this instrument and any such supplemental indenture, the 
provisions of the Trust Indenture Act that are deemed to be a part of and govern
this instrument, and any such supplemental indenture, respectively.

     "INTEREST PAYMENT DATE" means the Stated Maturity of an installment of 
interest on the Notes.

     "INVESTMENTS" means, with respect to any Person, all investments by such 
Person in other Persons (including Affiliates) in the form of direct or 
indirect loans (including guarantees of 




                                   -12-


<PAGE>

Indebtedness or other obligations), advances or capital contributions (excluding
advances to officers and employees of the type specified in clause (b) of the 
definition of Exempt Affiliate Transactions), purchases or other acquisitions 
for consideration of Indebtedness, Equity Interests or other securities and all
other items that are or would be classified as investments on a balance sheet 
prepared in accordance with GAAP or the acquisition, by purchase or 
otherwise, of all or substantially all of the business or assets of any other 
Person.

     "ISSUE DATE" means the date on which the Notes are first authorized and 
delivered under this Indenture.

     "LEGAL DEFEASANCE" has the meaning set forth in Section 8.02 hereof.

     "LIEN" means, with respect to any asset, any mortgage, lien, pledge, 
charge, security interest or encumbrance of any kind in respect of such asset,
whether or not filed, recorded or otherwise perfected under applicable law 
(including any conditional sale or other title retention agreement, any lease
in the nature thereof, any option or other agreement to sell or give a security
interest in and any filing of or agreement to give any financing statement 
under the Uniform Commercial Code (or equivalent statutes) of any jurisdiction).

     "MATERIAL CHANGE" means an increase or decrease (excluding changes that 
result solely from changes in prices) of more than 10% during a fiscal 
quarter in the discounted future net cash flows from proved oil and gas 
reserves of the Company and its Subsidiaries calculated in accordance with 
clause (a)(i) of the definition of Adjusted Consolidated Net Tangible Assets; 
provided, however, that the following will be excluded from the  calculation 
of Material Change: (i) any acquisition during the quarter of oil and gas 
reserves that have been estimated by independent petroleum engineers and on 
which a report or reports exists and (ii) any disposition of properties 
existing at the beginning of such quarter that have been disposed of pursuant 
to the provisions of this Indenture described below under Section 4.08.

     "MATURITY" means, when used with respect to a Note, the date on which 
the principal of such Note becomes due and payable as provided therein or in 
this Indenture, whether on the date specified in such Note as the fixed date 
on which the principal of such Note is due and payable, on the Change of 
Control Payment Date or the Asset Sale Payment Date, or by declaration of 
acceleration, call for redemption or otherwise.

     "MOODY'S" means Moody's Investors Service, Inc., or, if Moody's 
Investors Service, Inc. shall cease rating the specified debt securities and 
such ratings business with respect thereto shall have been transferred to a 
successor Person, such successor Person; PROVIDED that if Moody's Investors 
Service, Inc. ceases rating the specified debt securities and its ratings 
business with respect thereto shall not have been transferred to any 
successor Person or such successor Person is S&P, then "Moody's" shall mean 
any other nationally recognized rating agency (other than S&P) that rates the 
specified debt securities and that shall have been designated by the Company 
in an Officers' Certificate.




                                   -13-


<PAGE>
   
     "NET INCOME" means, with respect to any Person, the net income (loss) of 
such Person, determined in accordance with GAAP and before any reduction in 
respect of preferred stock dividends, excluding, however, (i) any gain (but 
not loss, except as provided in (b) below), together with any related 
provision for taxes on such gain (but not loss), realized in connection with 
(a) any Asset Sale (including, without limitation, dispositions pursuant to 
Sale and Leaseback Transactions) or (b) the disposition of any securities by 
such Person or any of its Subsidiaries or the extinguishment of any 
Indebtedness of such Person or any of its Subsidiaries, other than such 
losses arising out of the extinguishment of Indebtedness refinanced from the 
proceeds of the Notes and other securities issued contemporaneously with the 
Notes, (ii) any extraordinary or nonrecurring gain (but not loss, except as 
provided in (i) above), together with any related provision for taxes on such 
extraordinary or nonrecurring gain (but not loss), and (iii) any gain (but 
not loss) from currency exchange transactions not in the ordinary course of 
business consistent with past practice.
    
     "NET PROCEEDS" means the aggregate cash proceeds received by the Company 
or any of its Subsidiaries in respect of any Asset Sale (including, without 
limitation, any cash received upon the sale or other disposition of any 
noncash consideration received in any Asset Sale), net of the direct costs 
relating to such Asset Sale (including, without limitation, legal, accounting 
and investment banking fees, and sales commissions) and any relocation 
expenses incurred as a result thereof, taxes paid or payable as a result 
thereof, and any reserve for adjustment in respect of the sale price of such 
asset or assets established in accordance with GAAP.

     "NON-RECOURSE INDEBTEDNESS" means Indebtedness (i) as to which neither 
the Company nor any of its Subsidiaries (a) provides credit support of any 
kind (including any undertaking, agreement or instrument that would constitute
Indebtedness), (b) is directly or indirectly liable (as a Subsidiary Guarantor
or otherwise), or (c) constitutes the lender; and (ii) no default with respect
to which (including any rights that the holders thereof may have to take 
enforcement action against an Unrestricted Subsidiary) would permit (upon 
notice, lapse of time or both) any holder of any other Indebtedness of the 
Company or any of its Subsidiaries to declare a default on such other 
Indebtedness or cause the payment thereof to be accelerated or payable prior
to its Stated Maturity.

     "NOTES" has the meaning set forth in the Recitals of the Company and more
particularly means any of the Notes authenticated and delivered under this 
Indenture.

     "OBLIGATIONS" means any principal, interest, penalties, fees, 
indemnifications, reimbursements, damages and other liabilities payable under 
the documentation governing any Indebtedness.

     "OFFICER" means the Chairman of the Board of Directors, a Vice Chairman 
of the Board of Directors, the President, a Vice President, the Chief Financial
Officer, the Chief Accounting Officer, the Treasurer, an Assistant Treasurer, 
the Secretary or an Assistant Secretary of the Company or any Subsidiary 
Guarantor.

     "OFFICERS' CERTIFICATE" means a certificate signed by (i) the Chairman 
of the Board of Directors, a Vice Chairman of the Board of Directors, the 
President, the Chief Executive Officer or a Vice President of the Company or 
any Subsidiary Guarantor, and (ii) the Chief Financial Officer, the Chief 
Accounting Officer, the Treasurer, an Assistant Treasurer, the Secretary or 
an Assistant Secretary 

                                   -14-

<PAGE>
   
of the Company or any Subsidiary Guarantor, and delivered to the Trustee, 
which certificate shall comply with the provisions of Section 11.02 hereof; 
PROVIDED that any Officers' Certificate delivered pursuant to the first 
paragraph of Section 4.19 hereof shall be signed by the Chief Executive 
Officer, the Chief Financial Officer or the Chief Accounting Officer.
    
     "OIL AND GAS BUSINESS" means the business of the exploration for, and 
development, acquisition, and production of hydrocarbons, together with 
activities ancillary thereto (including with limitation, the gathering, 
processing, treatment, marketing and transportation of such production) and 
other related energy and natural resources businesses.

     "OIL AND GAS PURCHASE AND SALE CONTRACT" means with respect to any 
Person, any oil and gas agreements and other agreements or arrangements or 
any combination thereof entered into by such Person in the ordinary course of 
business and that is designed to provide protection against oil and natural 
gas price fluctuations.
   
     "OPINION OF COUNSEL" means a written opinion from legal counsel (who may 
be counsel to the Company, any Subsidiary Guarantor or the Trustee) who is 
acceptable to the Trustee, which opinion shall comply with the provisions of 
Section 11.02 hereof; provided that any Opinion of Counsel delivered pursuant 
to Section 8.04 hereof shall not be rendered by an employee of the Company or 
any of its Subsidiaries.
    
     "PARI PASSU INDEBTEDNESS" means Indebtedness of (a) the Company that is 
PARI PASSU with or subordinated to the Notes (other than the Notes) or (b) 
any Subsidiary Guarantor that is PARI PASSU with or subordinated to such 
Subsidiary Guarantor's Subsidiary Guarantee (other than such Subsidiary 
Guarantee or Indebtedness secured by such Subsidiary Guarantee).

     "PAYING AGENT" means any Person authorized by the Company to make payments
of principal, premium or interest with respect to the Notes on behalf of the 
Company.

   
     "PERMITTED INVESTMENTS" means (a) any Investments by the Subsidiaries of 
the Company in the Company; (b) any Investments in Cash Equivalents; (c) 
Investments made as a result of the receipt of noncash consideration from an 
Asset Sale that was made pursuant to and in compliance with Section 
4.08(b)(ii); (d) Investments outstanding as of the date of this Indenture; 
(e) Investments in Wholly Owned Subsidiaries that are engaged in the Oil and 
Gas Business and Investments in any Person that, as a result of such 
Investment (or a series of substantially contemporaneous Investments pursuant 
to a single plan) (x) such other Person becomes a Wholly Owned Subsidiary 
engaged in the Oil and Gas Business or (y) such other Person that is engaged 
in the Oil and Gas Business is merged or consolidated with or into, or 
transfers or conveys all or substantially all of its assets to the Company or 
a Wholly Owned Subsidiary in a transaction permitted under the Indenture; (f) 
entry into operating agreements, joint ventures, partnership agreements, 
working interests, royalty interests, mineral leases, processing agreements, 
farm-out agreements, contracts for the sale, transportation or exchange of 
oil and natural gas, unitization agreements, pooling arrangements, area of 
mutual interest agreements or other similar or customary agreements, 
transactions, properties, interests or arrangements, and Investments and 
expenditures in connection therewith or pursuant thereto, in each case made 
or entered into in the ordinary course of the Oil and Gas Business, 
excluding, however, Investments in corporations; (g) entry into any hedging 
arrangements in the ordinary course of business for the purpose of protecting 
the Company's or any Subsidiary's production against fluctuations in oil or 
natural gas prices; (h) shares of money mutual or similar funds having assets 
in excess of $500,000,000, and (i) Investments in an aggregate amount not to 
exceed $5,000,000 at any one time outstanding.
    

                                   -15-


<PAGE>

     "PERMITTED LIENS" means (a) liens for taxes, assessments and 
governmental charges not then due or the validity of which is being contested 
in good faith by appropriate proceedings, promptly instituted and diligently 
conducted, and for which adequate reserves have been established to the 
extent required by GAAP; (b) mechanics', workmen's, materialman's, operator's 
or similar liens arising in the ordinary course of business; (c) easements, 
rights of way, restrictions and other similar encumbrances incurred in the 
ordinary course of business or minor imperfections in title that do not 
impair the value of property for its intended use; (d) liens on, or related 
to, properties to secure all or part of the costs incurred in the ordinary 
course of business of exploration, drilling, development or operation 
thereof; (e) judgment and attachment liens not giving rise to an Event of 
Default or liens created by or existing from any litigation or legal 
proceeding that are currently being contested in good faith by appropriate 
proceedings, promptly instituted and diligently conducted, and for which 
adequate reserves have been made to the extent required by GAAP; (f) liens on 
deposits made in the ordinary course of business; (g) liens in favor of 
collecting or payor banks having a right of selloff, revocation, refund or 
chargeback with respect to money or instruments of the Company or any 
Subsidiary on deposit with or in possession of such bank (h) liens on 
pipeline or pipeline facilities which arise out of operation of law; (i) 
liens on deposits to secure public or statutory obligations or in lieu of 
surety or appeal bonds entered into in the ordinary course of business; (j) 
liens reserved in oil and gas leases for bonus or rental payments and for 
compliance with the terms of such leases; and (k) liens arising under 
partnership agreements, oil and gas leases, farmout agreements, division 
orders, contracts for the sale, purchase, exchange, transportation or 
processing of oil, gas or other hydrocarbons, unitization and pooling 
declarations and agreements, development agreements, operating agreements, 
area of mutual interest agreements and other agreements that are customary in 
the Oil and Gas Business.

     "PERMITTED REFINANCING INDEBTEDNESS" means any Indebtedness of the 
Company or any of its Subsidiaries issued in exchange for, or the net 
proceeds of which are used to extend, refinance, renew, replace, defease or 
refund, other Indebtedness of the Company or any of its Subsidiaries; 
provided that: (i) the principal amount of such Permitted Refinancing 
Indebtedness does not exceed the principal or accrued amount of the 
Indebtedness so extended, refinanced, renewed, replaced, defeased or refunded 
(plus the amount of reasonable expenses incurred in connection therewith); 
(ii) such Permitted Refinancing Indebtedness has a Weighted Average Life to 
Maturity and a final maturity date equal to or greater than the Weighted 
Average Life to Maturity and a final maturity date, respectively, of the 
Indebtedness being extended, refinanced, renewed, replaced, defeased or 
refunded; (iii) if the Indebtedness being extended, refinanced, renewed, 
replaced, defeased or refunded is subordinated in right of payment to the 
Notes, such Permitted Refinancing Indebtedness has a final maturity date 
later than the final maturity date of, and is subordinated in right of 
payment to, the Notes on terms at least as favorable to the Holders of Notes 
as those contained in the documentation governing the Indebtedness being 
extended, refinanced, renewed, replaced, defeased or refunded; and (iv) such 
Indebtedness is incurred either by the Company or by the Subsidiary who is 
the obligor on the Indebtedness being extended, refinanced, renewed, 
replaced, defeased or refunded.




                                   -16-


<PAGE>

     "PERSON" means any individual, corporation, partnership, joint venture, 
trust, unincorporated organization or government or any agency or political 
subdivision thereof.
   
     "PRINCIPAL PROPERTIES" means the oil and gas properties and other 
tangible assets and properties owned by Company on the date of this Indenture 
(collectively, the "Original Principal Properties") and assets and properties 
of the Company obtained in exchange for any of the Original Principal 
Properties.
    
     "PRODUCTION PAYMENTS" means, collectively, Dollar-Denominated Production 
Payments and Volumetric Production Payments.

     "PRO FORMA" means, with respect to any calculation made or required to 
be made pursuant to the terms hereof, a calculation in accordance with 
Article 11 of Regulation S-X promulgated under the Securities Act (to the 
extent applicable), as interpreted in good faith by the Board of Directors of 
the Company, or otherwise, a calculation made in good faith by the Board of 
Directors of the Company, as the case may be.

     "PROPERTY" means, with respect to any Person, any interest of such 
Person in any kind of property or asset, whether real, personal or mixed, 
tangible or intangible, excluding Capital Stock in any other Person.

     "PURCHASE MONEY OBLIGATIONS" of any Person means any obligations of such 
Person to any seller or any other Person incurred or assumed to finance the 
construction and/or acquisition of real or personal property to be used in 
the business of such Person or any of its Subsidiaries in an amount that is 
not more than 100% of the cost of such property, and incurred within 180 days 
after the date of such construction or acquisition (excluding accounts 
payable to trade creditors incurred in the ordinary course of business).

     "QUALIFIED STOCK" means, for any Person, any and all Capital Stock of 
such Person, other than Disqualified Stock.  

     "RECORD DATE" means, for the interest payable on any Interest Payment 
Date, the date specified in Section 2.11 hereof.

     "REDEMPTION DATE" means, when used with respect to any Note or part 
thereof to be redeemed hereunder, the date fixed for redemption of such Notes 
pursuant to the terms of the Notes and this Indenture.

     "REDEMPTION PRICE" means when used with respect to any Note or part 
thereof to be redeemed hereunder, the price fixed for redemption of such Note 
pursuant to the terms of the Notes and this Indenture, plus accrued and 
unpaid interest, if any, to the Redemption Date.

     "REGISTRAR" has the meaning set forth in Section 2.03 hereof.

     "REPRESENTATIVE" means the indenture trustee or other trustee, agent or 
representative for any Senior Indebtedness or Guarantor Senior Indebtedness.

     "RESTRICTED INVESTMENT" means an Investment other than a Permitted 
Investment.




                                   -17-


<PAGE>

     "RESTRICTED PAYMENT" has the meaning set forth in Section 4.11 hereof.

     "S&P" means Standard & Poor's Ratings Group, a division of McGraw Hill 
Corporation, or, if Standard & Poor's Ratings Group shall cease rating the 
specified debt securities and such ratings business with respect thereto 
shall have been transferred to a successor Person, such successor Person; 
PROVIDED that if Standard & Poor's Ratings Group ceases rating the specified 
debt securities and its ratings business with respect thereto shall not have 
been transferred to any successor Person or such successor Person is Moody's, 
then "S&P" shall mean any other nationally recognized rating agency (other 
than Moody's) that rates the specified debt securities and that shall have 
been designated by the Company in an Officers' Certificate.

     "SALE AND LEASEBACK TRANSACTION" means, with respect to the Company or 
any of its Subsidiaries, any arrangement with any Person providing for the 
leasing by the Company or any of its Subsidiaries as lessee of any principal 
property, acquired or placed into service more than 180 days prior to such 
arrangement (except leases of two years of less), whereby such property has 
been or is to be sold or transferred by the Company or any of its 
Subsidiaries to such Person or its Affiliates.

     "SECURITIES ACT" means the Securities Act of 1933, as amended, and the 
rules and regulations promulgated thereunder.

     "SECURITY REGISTER" has the meaning set forth in Section 2.03 hereof.

     "SENIOR BANK INDEBTEDNESS" means the Indebtedness outstanding under the 
Credit Facility.

     "SENIOR INDEBTEDNESS" means (i) the Senior Bank Indebtedness and (ii) 
any other Indebtedness permitted to be incurred by the Company under the 
terms of this Indenture, unless the instrument under which such Indebtedness 
is incurred expressly provides that it is subordinated in right of payment to 
any Indebtedness for money borrowed.  Notwithstanding anything to the 
contrary in the foregoing, Senior Indebtedness will not include (w) any 
liability for federal, state, local or other taxes owed or owing by the 
Company, (x) any Indebtedness of the Company to any of its Subsidiaries, 
Unrestricted Subsidiaries or other Affiliates, (y) any trade payables or (z) 
any Indebtedness that is incurred in violation of this Indenture.

     "SENIOR REVOLVING INDEBTEDNESS" means revolving credit borrowings and 
letters of credit under the Credit Facility and/or any successor facility or 
facilities.

     "SPECIAL RECORD DATE" means a date fixed by the Trustee pursuant to 
Section 2.11 for the payment of Defaulted Interest.

     "STATED MATURITY" means, with respect to any security, the date 
specified in such security as the fixed date on which the payment of 
principal of such security is due and payable, including pursuant to any 
mandatory redemption provision (but excluding any provision providing for the 
repurchase of such security at the option of the holder thereof upon the 
happening of any contingency unless such contingency has occurred), and, when 
used with respect to any installment of interest on such security, the fixed 
date on which such installment of interest is due and payable.

     "SUBSIDIARY" means, with respect to any Person, (i) any corporation, 
association or other business entity of which more than 50% of the total 
voting power of shares of Capital Stock entitled (without regard to the 
occurrence of any contingency) to vote in the election of directors, managers 


                                     -18-

<PAGE>


or trustees thereof is at the time owned or controlled, directly or 
indirectly, by such Person or one or more of the other Subsidiaries of that 
Person (or a combination thereof) and (ii) any partnership (a) the sole 
general partner or the managing general partner of which is such Person or a 
Subsidiary of such Person or (b) the only general partners of which are such 
Person or of one or more Subsidiaries of such Person (or any combination 
thereof).  Notwithstanding the foregoing, an Unrestricted Subsidiary shall 
not be a Subsidiary of the Company for any purposes of this Indenture.

   
     "SUBSIDIARY GUARANTEE" means the guarantee of the Notes by a Subsidiary 
Guarantor pursuant to Exhibit C and Article XI under which such Subsidiary 
Guarantor guarantees the Notes.

     "SUBSIDIARY GUARANTOR" means each of the Subsidiaries that agrees to 
guarantee the Notes.
    

     "TEMPORARY NOTES" has the meaning set forth in Section 2.09 hereof.

     "TRUST INDENTURE ACT" means the Trust Indenture Act of 1939 (15 U.S.C. 
SECTION Section 77aaa-77bbbb) as in effect on the date of this Indenture 
except as required by Section 9.04 hereof; provided that in the event the 
Trust Indenture Act of 1939 is amended after such date, "Trust Indenture Act" 
means, to the extent required by any such amendment, the Trust Indenture Act 
of 1939, as so amended.

     "TRUST OFFICER" means any officer or assistant officer of the Trustee 
assigned by the Trustee to administer this Indenture.

     "TRUSTEE" means the party named as such in this Indenture until a 
successor replaces it in accordance with the provisions of this Indenture 
and, thereafter, means such successor.

     "U.S. GOVERNMENT OBLIGATIONS" means (i) securities that are (a) direct 
obligations of the United States of America for the payment of which the full 
faith and credit of the United States of America is pledged or (b) 
obligations of a Person controlled or supervised by and acting as an agency 
or instrumentality of the United States of America the payment of which is 
unconditionally guaranteed as a full faith and credit obligation by the 
United States of America, which, in either case, are not callable or 
redeemable at the option of the issuer thereof; and (ii) depository receipts 
issued by a bank (as defined in Section 3(a)(2) of the Securities Act) as 
custodian with respect to any U.S. Government Obligation which is specified 
in clause (i) above and held by such bank for the account of the holder of 
such depository receipt, or with respect to any specific payment of principal 
or interest on any U.S. Government Obligation which is so specified and held; 
provided that (except as required by law) such custodian is not authorized to 
make any deduction from the amount payable to the holder of such depository 
receipt from any amount received by the custodian in respect of the U.S. 
Government Obligation or the specific payment of principal or interest of the 
U.S. Government Obligation evidenced by such depository receipt.  Investments 
in U.S. Government Obligations may be made through or with the Trustee.


                                     -19-

<PAGE>

     "UNRESTRICTED SUBSIDIARY" means each entity, if designated by the Board 
of Directors of the Company as Unrestricted Subsidiaries pursuant to a Board 
Resolution pursuant to Section 4.10 hereof.

     "VOLUMETRIC PRODUCTION PAYMENTS" means volumetric production payment 
obligations of the Company or any of its Subsidiaries that are or, upon the 
occurrence of a contingent event, would be recorded as deferred revenue in 
accordance with GAAP, together with all undertakings and obligations of the 
Company or any of its Subsidiaries in connection therewith, which will be 
deemed to constitute debt for borrowed money for purpose of this Indenture.

     "VOTING STOCK" of a corporation means all classes of Capital Stock of 
such corporation then outstanding and normally entitled to vote in the 
election of directors.

     "WEIGHTED AVERAGE LIFE TO MATURITY" means, when applied to any 
Indebtedness at any date, the number of years obtained by dividing (i) the 
sum of the product obtained by multiplying (a) the amount of each then 
remaining installment, sinking fund, serial maturity or other required 
payments of principal, including payments at final maturity, in respect 
thereof, by (b) the number of years (calculated to the nearest one-twelfth) 
that will elapse between such date  and the making of such payment, by (ii) 
the then outstanding principal amount of such Indebtedness.

     "WHOLLY OWNED SUBSIDIARY" of any Person means a Subsidiary of such 
Person (i) all of the outstanding Capital Stock or other ownership interests 
of which (other than directors' qualifying shares) shall at the time be owned 
by such Person or by one or more Wholly Owned Subsidiaries of such Person or 
(ii) organized in a foreign jurisdiction and is required by the applicable 
laws and regulations of such foreign jurisdiction to be partially owned by 
the goernment of such foreign jurisdiction or individual or corporate 
citizens of such foreign jurisdiction in order for such Subsidiary to 
transact business in such foreign jurisdiction, provided that such Person or 
one or more Wholly Owned Subsidiaries of such Person, owns the remaining 
Capital Stock or ownership interest in such Subsidiary and, by contract or 
otherwise, controls the management and business of such Subsidiary and 
derives the economic benefits of ownership of such Subsidiary to 
substantially the same extent as if such Subsidiary were a wholly owned 
Subsidiary. Unrestricted Subsidiaries shall not be included in the definition 
of Wholly Owned Subsidiary for any purposes of this Indenture.

     SECTION 1.02.  INCORPORATION BY REFERENCE OF TRUST INDENTURE ACT. (a)  
This Indenture is expressly made subject to the Trust Indenture Act as if 
this Indenture were, on the date of this Indenture, subject to the Trust 
Indenture Act under the provisions of such statute and such provisions are 
incorporated by reference in this Indenture.

         (b)     Whenever this Indenture refers to a provision of the Trust 
Indenture Act, the provision is incorporated by reference in and made a part 
of this Indenture.  The following Trust Indenture Act terms incorporated by 
reference in this Indenture have the following meanings:

          "indenture securities" means the Notes.

          "indenture security holder" means a Holder.
 
          "indenture to be qualified" means this Indenture.

          "indenture trustee" or "institutional trustee" means the Trustee.


                                     -20-

<PAGE>

          "obligor" on the indenture securities means the Company or other 
     obligor on the Notes, if any.

     All other Trust Indenture Act terms used or incorporated by reference in 
this Indenture that are defined by the Trust Indenture Act, defined by Trust 
Indenture Act reference to another statute or defined by Commission rule have 
the meanings assigned to them therein.

     SECTION 1.03.  RULES OF CONSTRUCTION.  Unless the context otherwise 
requires:

          (a) the words "herein," "hereof" and "hereunder," and other words of 
     similar import, refer to this Indenture as a whole and not to any 
     particular Article, Section or other subdivision;

          (b) "or" is not exclusive;

          (c) "including" means including without limitation;

          (d) the principal amount of any noninterest bearing or other discount 
     security, at any date shall be the principal amount thereof that would be 
     shown on a balance sheet of the issuer dated such date prepared in 
     accordance with GAAP; and

          (e) when used with respect to the Notes, the term "principal amount" 
     shall mean the principal amount thereof at the Stated Maturity of such 
     principal amount.

     SECTION 1.04.  FORM OF DOCUMENTS DELIVERED TO TRUSTEE.  In any case where 
several matters are required to be certified by, or covered by an opinion of, 
any specified Person, it is not necessary that all such matters be certified 
by, or covered by the opinion of, only one such Person, or that they be so 
certified or covered by only one document, but one such Person may certify or 
give an opinion with respect to some matters and one or more other such 
Persons as to other matters, and any such Person may certify or give an 
opinion as to such matters in one or several documents.

     Any certificate or opinion of an officer of the Company or a Subsidiary 
Guarantor may be based, insofar as it relates to legal matters, upon a 
certificate or opinion of, or representations by, counsel, unless such 
officer knows, or in the exercise of reasonable care should know, that the 
certificate or opinion or representations with respect to the matters upon 
which his certificate or opinion is based are erroneous. Any such certificate 
or Opinion of Counsel may be based, insofar as it relates to factual matters, 
upon a certificate or opinion of, or representations by, an officer or 
officers of the Company or a Subsidiary Guarantor stating that the 
information with respect to such factual matters is in the possession of the 
Company or such Subsidiary Guarantor, unless such counsel knows, or in the 
exercise of reasonable care should know, that the certificate or opinion or 
representations with respect to such matters are erroneous.


                                     -21-

<PAGE>

     Where any Person is required to make, give or execute two or more 
applications, requests, consents, certificates, statements, opinions or other 
instruments under this Indenture, they may, but need not, be consolidated and 
form one instrument.

     SECTION 1.05.  ACTS OF HOLDERS. (a)  Any request, demand, authorization, 
direction, notice, consent, waiver or other action provided by this Indenture 
to be given or taken by Holders may be embodied in and evidenced by one or 
more instruments of substantially similar tenor signed by such Holders in 
person or by an agent duly appointed in writing; and, except as herein 
otherwise expressly provided, such action shall become effective when such 
instrument or instruments are delivered to the Trustee and, where it is 
hereby expressly required, to the Company and the Subsidiary Guarantors.  
Such instrument or instruments (and the action embodied therein and evidenced 
thereby) are herein sometimes referred to as the "Act" of the Holders signing 
such instrument or instruments.  Proof of execution of any such instrument or 
of a writing appointing any such agent shall be sufficient for any purpose of 
this Indenture and (subject to Section 7.01) conclusive in favor of the 
Trustee and the Company and the Subsidiary Guarantors, if made in the manner 
provided in this Section.

     (b)  The fact and date of the execution by any Person of any such 
instrument or writing may be proved by the affidavit of a witness of such 
execution or by an acknowledgment of a notary public or other officer 
authorized by law to take acknowledgments of deeds, certifying that the 
individual signing such instrument or writing acknowledged to him the 
execution thereof.  Where such execution is by a signer acting in a capacity 
other than such signer's individual capacity, such certificate or affidavit 
shall also constitute sufficient proof of the signer's authority.  The fact 
and date of the execution of any such instrument or writing, or the authority 
of the person executing the same, may also be proved in any other manner 
which the Trustee deems sufficient.

     SECTION 1.06.  SATISFACTION AND DISCHARGE.  This Indenture shall cease 
to be of further effect and the Trustee, on receipt of a Company Order 
requesting such action, shall execute proper instruments acknowledging 
satisfaction and discharge of this Indenture, when (a) either (i) all 
outstanding Notes have been delivered to the Trustee for cancellation or (ii) 
all such Notes not theretofore delivered to the Trustee for cancellation have 
become due and payable and the Company or the Subsidiary Guarantors have 
irrevocably deposited or caused to be deposited with the Trustee as trust 
funds in trust for the purpose (x) money in an amount, (y) U.S. Government 
Obligations or (z) a combination thereof, sufficient, in the case of deposits 
pursuant to the foregoing clauses (y) or (z), as established in the opinion 
of a nationally recognized firm of independent public accountants expressed 
in a written certification thereof delivered to the Trustee, to pay and 
discharge the entire indebtedness on such Notes, for principal (and premium, 
if any) and interest, if any, to the date of such deposit together with 
irrevocable instructions from the Company in form and substance satisfactory 
to the Trustee directing the Trustee to apply such funds to the payment 
thereof; (b) the Company or the Subsidiary Guarantors have paid or caused to 
be paid all other sums payable hereunder by the Company; and (c) the Company 
or the Subsidiary Guarantors have delivered to the Trustee an Officers' 
Certificate and an Opinion of Counsel, each stating that all conditions 
precedent herein provided for relating to the satisfaction and discharge of 
this Indenture have been complied with. Notwithstanding the satisfaction and 
discharge of this Indenture pursuant to this Section 1.06, the obligations of 
the Company and the Subsidiary Guarantors to the Trustee under Section 7.07 

                                     -22-

<PAGE>

hereof, and, if money shall have been deposited with the Trustee in trust for 
the Holders pursuant to this Section 1.06, the obligations of the Trustee 
under this Section 1.06 hereof shall survive.

     All money deposited with the Trustee pursuant to this Section 1.06 shall 
be held in trust and applied by it, in accordance with the provisions of the 
Notes and this Indenture, to the payment, either directly or through any 
Paying Agent, to the Persons entitled thereto, of the principal (and premium, 
if any) and interest, if any, for the payment of which such money has been 
deposited with the Trustee.  If the Trustee or Paying Agent is unable to 
apply any money [or U.S. Government Obligations] in accordance with this 
Section 1.06 by reason of any legal proceeding or by reason of any order or 
judgment of any court or governmental authority enjoining, restraining or 
otherwise prohibiting such application, the Company's and the Subsidiary 
Guarantors' obligations under this Indenture and the Notes shall be revived 
and reinstated as though no deposit had occurred pursuant to this Section 
1.06 until such time as the Trustee or Paying Agent is permitted to apply all 
such money or U.S. Government Obligations in accordance with this Section 
1.06; PROVIDED, that if the Company or the Subsidiary Guarantors have made 
any payment on any Notes because of the reinstatement of its obligations, the 
Company and the Subsidiary Guarantors shall be subrogated to the rights of 
the Holders of such Notes to receive such payment from the cash or U.S. 
Government Obligations held by the Trustee or Paying Agent.

     The Company and the Subsidiary Guarantors shall pay and indemnify the 
Trustee against any tax, fee or other charges imposed on or assessed against 
the U.S. Government Obligations deposited pursuant to this Section 1.06 or the 
principal and interest received in respect thereof other than any such tax, fee 
or other charge which by law is for the account of the Holders of outstanding 
Notes.

                                 ARTICLE II

                                 THE NOTES

     SECTION 2.01.  FORM AND DATING. (a)  The Notes and the certificate of 
authentication of the Trustee thereon shall be substantially in the form of 
Exhibit A or Exhibit B hereto, as applicable, which are hereby incorporated 
in and expressly made a part of this Indenture.

     (b)  The Notes may have such letters, numbers or other marks of 
identification and such legends and endorsements, stamped, printed, 
lithographed or engraved thereon, (i) as the Company may deem appropriate and 
as are not inconsistent with the provisions of this Indenture, (ii) such as 
may be required to comply with this Indenture, any law or any rule of any 
securities exchange on which the Notes may be listed and (iii) such as may be 
necessary to conform to customary usage.  Each Note shall be dated the date 
of its authentication by the Trustee.

     (c)  The Notes shall be issued initially in the form of a permanent, 
global note in definitive, fully registered form, without coupons, 
substantially in the form of Exhibit A hereto (the "Global Note"). Upon 
issuance, such Global Note shall be duly executed by the Company and 
authenticated by the Trustee as hereinafter provided and deposited with the 
Trustee as custodian for the Depositary.  


                                     -23-

<PAGE>

Any Certificated Note that may be issued pursuant to Section 2.06(a) hereof, 
shall be issued in the form of a note in definitive, fully registered form, 
without coupons, substantially in the form set forth in Exhibit B hereto.  
Upon issuance, any such Certificated Note shall be duly executed by the 
Company and authenticated by the Trustee as hereinafter provided.

     (d)  Each Global Note shall bear the following legend on the face thereof:

     UNLESS THIS NOTE IS PRESENTED BY AN AUTHORIZED REPRESENTATIVE OF THE 
     DEPOSITORY TRUST COMPANY TO COSTILLA ENERGY, INC. OR THE REGISTRAR FOR 
     REGISTRATION OF TRANSFER OR EXCHANGE AND ANY NOTE ISSUED IS REGISTERED 
     IN THE NAME OF CEDE & CO. OR SUCH OTHER ENTITY AS HAS BEEN REQUESTED BY 
     AN AUTHORIZED REPRESENTATIVE OF THE DEPOSITORY TRUST COMPANY (AND ANY 
     PAYMENT HEREON IS MADE TO CEDE & CO. OR TO SUCH OTHER ENTITY AS HAS BEEN 
     REQUESTED BY AN AUTHORIZED REPRESENTATIVE OF THE DEPOSITORY TRUST 
     COMPANY), ANY TRANSFER, PLEDGE OR OTHER USE HEREOF FOR VALUE OR 
     OTHERWISE BY OR TO ANY PERSON IS WRONGFUL SINCE THE REGISTERED OWNER 
     HEREOF, CEDE & CO., HAS AN INTEREST HEREIN.

     TRANSFER OF THIS GLOBAL NOTE SHALL BE LIMITED TO TRANSFERS IN WHOLE, AND 
     NOT IN PART, TO NOMINEES OF THE DEPOSITORY TRUST COMPANY OR TO A 
     SUCCESSOR THEREOF OR SUCH SUCCESSOR'S NOMINEE AND TRANSFERS OF INTERESTS 
     IN THIS GLOBAL NOTE SHALL BE LIMITED TO TRANSFERS MADE IN ACCORDANCE 
     WITH THE RESTRICTIONS SET FORTH IN SECTION 2.06 OF THE INDENTURE, DATED 
     AS OF ________________, 1996, BETWEEN COSTILLA ENERGY, INC.  AND THE 
     TRUSTEE NAMED THEREIN, PURSUANT TO WHICH THIS NOTE WAS ISSUED.

     (e)  Definitive Notes shall be typed, printed, lithographed or engraved 
or produced by any combination of such methods or produced in any other 
manner permitted by the rules of  any securities exchange on which such Notes 
may be listed, all as determined by the officers of the Company executing 
such Notes, as evidenced by their execution of such Notes.

   
     SECTION 2.02.  EXECUTION AND AUTHENTICATION.  The aggregate principal 
amount of Notes outstanding at any time shall not exceed $100,000,000.  The 
Notes shall be executed on behalf of the Company by its Chief Executive 
Officer, its President, any Executive Vice President or any Senior Vice 
President, under its corporate seal reproduced or imprinted on the Notes by 
facsimile or otherwise, and shall be attested by the Company's Secretary or 
one of its Assistant Secretaries, in each case by manual or facsimile 
signature.
    

     The Notes shall be authenticated by manual signature of an authorized 
signatory of the Trustee and shall not be valid for any purpose unless so 
authenticated.


                                     -24-

<PAGE>

     In case any officer of the Company whose signature shall have been 
placed upon any of the Notes shall cease to be such officer of the Company 
before authentication of such Notes by the Trustee and the issuance and 
delivery thereof, such Notes may, nevertheless, be authenticated by the 
Trustee and issued and delivered with the same force and effect as though 
such Person had not ceased to be such officer of the Company.

     Upon compliance by the Company with the provisions of the previous 
paragraph, the Trustee shall, upon receipt of a Company Order requesting such 
action, authenticate Notes for original issuance in an aggregate principal 
amount not to exceed $100,000,000 in the form of the Global Note.  Such 
Company Order shall specify the amount of Notes to be authenticated and the 
date on which the Notes are to be authenticated and shall further provide 
instructions concerning registration, amounts for each Holder and delivery.

     Upon the occurrence of any event specified in Section 2.06(a) hereof and 
compliance by the Company with the provisions of the paragraph preceding the 
immediately preceding paragraph, the Company shall execute and the Trustee 
shall authenticate and make available for delivery to each beneficial owner 
identified by the Depositary, in exchange for such beneficial owner's 
interest in the Global Note or Certificated Notes, as the case may be, 
representing Notes theretofore represented by the Global Note.

     A Note shall not be valid or entitled to any benefit under this 
Indenture or obligatory for any purpose unless executed by the Company and 
authenticated by the manual signature of the Trustee as provided herein.  The 
signature of an authorized signatory of the Trustee shall be conclusive 
evidence, and the only evidence, that such Note has been authenticated and 
delivered under this Indenture.

     The Trustee may appoint an authenticating agent reasonably acceptable to 
the Company to authenticate the Notes.  Unless limited by the terms of such 
appointment, an authenticating agent may authenticate Notes whenever the 
Trustee may do so.  Each reference in this Indenture to authentication by the 
Trustee includes authentication by such agent.  Any authenticating agent of 
the Trustee shall have the same rights hereunder as any Registrar or Paying 
Agent.

     SECTION 2.03.  REGISTRAR AND PAYING AGENT.  The Company shall maintain, 
pursuant to Section 4.02 hereof, an office or agency where the Notes may be 
presented for registration of transfer or for exchange.  The Company shall 
cause to be kept at such office a register (the register maintained in such 
office being herein sometimes referred to as the "Security Register") in 
which, subject to such reasonable regulations as it may prescribe, the 
Company shall provide for the registration of Notes and of transfers of Notes 
entitled to be registered or transferred as provided herein.  The Trustee, at 
its Corporate Trust Office, is initially appointed "Registrar" for the 
purpose of registering Notes and transfers of Notes as herein provided.  The 
Company may, upon written notice to the Trustee, change the designation of 
the Trustee as Registrar and appoint another Person to act as Registrar for 
purposes of this Indenture.  If any Person other than the Trustee acts as 
Registrar, the Trustee shall have the right at any time, upon reasonable 
notice, to inspect or examine the Security Register and 


                                     -25-

<PAGE>

to make such inquiries of the Registrar as the Trustee shall in its 
discretion deem necessary or desirable in performing its duties hereunder.

     The Company shall enter into an appropriate agency agreement with any 
Person designated by the Company as Registrar or Paying Agent that is not a 
party to this Indenture, which agreement shall incorporate the provisions of 
the Trust Indenture Act and shall implement the provisions of this Indenture 
that relate to such Registrar or Paying Agent.  Prior to the designation of 
any such Person, the Company shall, by written notice (which notice shall 
include the name and address of such Person), inform the Trustee of such 
designation.  If the Company fails to maintain a Registrar or Paying Agent, 
the Trustee shall act as such.

     Subject to Section 2.06, upon surrender for registration of transfer of 
any Note at an office or agency of the Company designated for such purpose, 
the Company shall execute, and the Trustee shall authenticate and make 
available for delivery, in the name of the designated transferee or 
transferees, one or more new Notes of any authorized denomination or 
denominations, of like tenor and aggregate principal amount, all as requested 
by the transferor.

     Every Note presented or surrendered for registration of transfer or for 
exchange shall (if so required by the Company, the Trustee or the Registrar) 
be duly endorsed, or be accompanied by a duly executed instrument of transfer 
in form satisfactory to the Company, the Trustee and the Registrar, by the 
Holder thereof or such Holder's attorney duly authorized in writing.

     SECTION 2.04.  PAYING AGENT TO HOLD MONEY IN TRUST.  On or prior to each 
due date of the principal, premium, or any payment of interest, if any, with  
respect to any Note, the Company shall deposit with the Paying Agent a sum 
sufficient to pay such principal, premium or interest when so becoming due.

     The Company shall require each Paying Agent (other than the Trustee) to 
agree in writing that such Paying Agent, shall hold in trust for the benefit 
of Holders or the Trustee all money held by such Paying Agent for the payment 
of principal, premium or interest with respect to the Notes, shall notify the 
Trustee of any default by the Company in making any such payment and at any 
time during the continuance of any such default, upon the written request of 
the Trustee, shall forthwith pay to the Trustee all sums held in trust by 
such Paying Agent.

     The Company at any time may require a Paying Agent to pay all money held 
by it to the Trustee and to account for any funds disbursed by such Paying 
Agent.  Upon complying with this Section 2.04, the Paying Agent shall have no 
further liability for the money delivered to the Trustee.

     SECTION 2.05.  GLOBAL NOTES. (a)  So long as a Global Note is registered 
in the name of the Depositary or its nominee, members of, or participants in, 
the Depositary ("Agent Members") shall have no rights under this Indenture 
with respect to the Global Note held on their behalf by the Depositary or the 
Trustee as its custodian, and the Depositary may be treated by the Company, 
the Trustee and any agent of the Company or the Trustee as the absolute owner 
of such Global Note for 


                                     -26-

<PAGE>

all purposes.  Notwithstanding the foregoing, nothing herein shall (i) 
prevent the Company, the Trustee or any agent of the Company or the Trustee, 
from giving effect to any written certification, proxy or other authorization 
furnished by the Depositary or (ii) impair, as between the Depositary and its 
Agent Members, the operation of customary practices governing the exercise of 
the rights of a Holder of Notes.

     (b)  The Holder of a Global Note may grant proxies and otherwise 
authorize any Person, including Agent Members and Persons that may hold 
interests in such Global Note through Agent Members, to take any action which 
a Holder of Notes is entitled to take under this Indenture or the Notes.

     (c)  Whenever, as a result of an optional redemption of Notes by the 
Company, a Change of Control Offer, an Asset Sale Offer or an exchange 
pursuant to the second sentence of Section 2.06(a) hereof, a Global Note is 
redeemed, repurchased or exchanged in part, such Global Note shall be 
surrendered by the Holder thereof to the Trustee who shall cause an 
adjustment to be made to Schedule A thereof so that the principal amount of 
such Global Note will be equal to the portion of such Global Note not 
redeemed, repurchased or exchanged and shall thereafter return such Global 
Note to such Holder, provided that any such Global Note shall be in a 
principal amount of $1,000 or an integral multiple thereof.

     SECTION 2.06.  TRANSFER AND EXCHANGE.

     (a)  The Global Note shall be exchanged by the Company for one or more 
Certificated Notes if (a) the Depositary (i) has notified the Company that it 
is unwilling or unable to continue as, or ceases to be, a clearing agency 
registered under Section 17A of the Exchange Act and (ii) a successor to the 
Depositary registered as a clearing agency under Section 17A of the Exchange 
Act is not able to be appointed by the Company within 90 calendar days or (b) 
the Depositary is at any time unwilling or unable to continue as Depositary 
and a successor to the Depositary is not able to be appointed by the Company 
within 90 calendar days.  If an Event of Default occurs and is continuing, 
the Company shall, at the request of the Holder thereof, exchange all or part 
of the Global Note for one or more Certificated Notes; PROVIDED that the 
principal amount of each of such Certificated Notes and such Global Note, 
after such exchange, shall be $1,000 or an integral multiple thereof.  In 
addition, the Holder of a beneficial interest in the Global Note may at any 
time exchange such interest for a Certificated Note in a principal amount of 
$1,000 or an integral multiple thereof.  Whenever a Global Note is exchanged 
as a whole for one or more Certificated Notes, such Global Note shall be 
surrendered by the Holder thereof to the Trustee for cancellation.  Whenever 
a Global Note is exchanged in part for one or more Certificated Notes 
pursuant to this Section 2.06(a), it shall be surrendered by the Holder 
thereof to the Trustee and the Trustee shall make the appropriate notations 
thereon pursuant to Section 2.05(c) hereof.  All Certificated Notes issued in 
exchange for a Global Note or any portion thereof shall be registered in such 
names, and delivered, as the Depositary shall instruct the Trustee.


                                     -27-

<PAGE>

     (b)  A Holder may transfer a Note only upon the surrender of such Note 
for registration of transfer.  No such transfer shall be effected until, and 
the transferee shall succeed to the rights of a Holder only upon, final 
acceptance and registration of the transfer in the Security Register by the 
Registrar.  When Notes are presented to the Registrar with a request to register
the transfer of, or to exchange, such Notes, the Registrar shall register the 
transfer or make such exchange as requested if its requirements for such 
transactions and any applicable requirements hereunder are satisfied.  To permit
registrations of transfers and exchanges, the Company shall execute and the 
Trustee shall authenticate Certificated Notes at the Registrar's request.

     (c)  The Company shall not be required to make and the Registrar need 
not register transfers or exchanges of Certificated Notes (i) selected for 
redemption (except, in the case of Certificated Notes to be redeemed in part, 
the portion thereof not to be redeemed) and (ii) for a period of 15 calendar 
days before a selection of Notes to be redeemed.

     (d)  No service charge shall be made for any registration of transfer or 
exchange of Notes, but the Company may require payment by Holders of a sum 
sufficient to cover any tax or other governmental charge that may be imposed 
in connection with any registration of transfer of Notes.

     (e)  All Notes issued upon any registration of transfer or exchange 
pursuant to the terms of this Indenture will evidence the same debt and will 
be entitled to the same benefits under this Indenture as the Notes 
surrendered for such registration of transfer or exchange.

     (f)  Any Holder of a Global Note shall, by acceptance of such Global 
Note, agree that transfers of beneficial interests in such Global Note may be 
effected only through a book entry system maintained by such Holder (or its 
agent), and that ownership of a beneficial interest in the Notes represented 
thereby shall be required to be reflected in book entry form.  Transfers of a 
Global Note shall be limited to transfers in whole and not in part, to the 
Depositary, its successors, and their respective nominees. Interests of 
beneficial owners in a Global Note shall be transferred in accordance with 
the rules and procedures of the Depositary (or its successors).

     SECTION 2.07.  REPLACEMENT NOTES.  If any mutilated Note is surrendered 
to the Trustee, the Company shall execute and upon its written request the 
Trustee shall authenticate and make available for delivery, in exchange for 
any such mutilated Note, a new Note containing identical provisions and of 
like principal amount, bearing a number not contemporaneously outstanding.

     If there shall be delivered to the Company and the Trustee (i) evidence 
to their satisfaction of the destruction, loss or theft of any Note and (ii) 
such security or indemnity as may be required by them to save either of them 
and any agent of each of them harmless, then, in the absence of notice to the 
Company or the Trustee that such Note has been acquired by a bona fide 
purchaser, the Company shall execute and upon its request the Trustee shall 
authenticate and make available for delivery, in lieu of any such destroyed, 
lost or stolen Note, a new Note containing identical provisions and of like 
principal amount, bearing a number not contemporaneously outstanding.



                                   -28-


<PAGE>

     In case any such mutilated, destroyed, lost or stolen Note has become or 
is about to become due and payable, the Company in its discretion may, 
instead of issuing a new Note, pay such Note.

     Upon the issuance of any new Note under this Section 2.07, the Company 
may require the payment by the Holder of a sum sufficient to cover any tax or 
other governmental charge that may be imposed in relation thereto and any 
other expenses (including the fees and expenses of the Trustee) connected 
therewith.

     Every new Note issued pursuant to this Section 2.07 in lieu of any 
destroyed, lost or stolen Note shall constitute an original additional 
contractual obligation of the Company, whether or not the destroyed, lost or 
stolen Note shall be at any time enforceable by anyone, and shall be entitled 
to all the benefits of this Indenture equally and proportionately with any 
and all other Notes duly issued hereunder.

     The provisions of this Section 2.07 are exclusive and shall preclude (to 
the extent lawful) all other rights and remedies with respect to the 
replacement or payment of mutilated, destroyed, lost or stolen Notes.

     SECTION 2.08.  OUTSTANDING NOTES.  Notes outstanding at any time are all
Notes authenticated by the Trustee except for those canceled by it, those 
delivered to it for cancellation, those paid pursuant to Section 2.07 and 
those described in this Section 2.08 as not outstanding.  A Note does not 
cease to be outstanding because the Company or an Affiliate of the Company 
holds such Note.

     If a Note is replaced pursuant to Section 2.07 hereof, it ceases to be 
outstanding unless the Trustee and the Company receive proof satisfactory to 
them that such replaced Note is held by a bona fide purchaser.

     If the Paying Agent segregates and holds in trust, in accordance with 
this Indenture, on a redemption date or Maturity date money sufficient to pay 
all principal, premium, if any, and interest payable on that date with 
respect to the Notes (or portions thereof) to be redeemed or maturing, as the 
case may be, then on and after that date such Notes (or such portions 
thereof) shall cease to be outstanding and interest on them shall cease to 
accrue.

     In determining whether the Holders of the required principal amount of 
Notes have concurred in any direction, waiver or consent or any amendment, 
modification or other change to this Indenture, Notes held or beneficially 
owned by the Company or a Subsidiary or Unrestricted Subsidiary of the 
Company or by an Affiliate of the Company or of a Subsidiary or Unrestricted 
Subsidiary of the Company or by agents of any of the foregoing shall be 
disregarded, except that for the purposes of determining whether the Trustee 
shall be protected in relying on any such direction, waiver or consent or any 
amendment, modification or other change to this Indenture, only Notes which a 
Trust Officer actually knows are so owned shall be so disregarded. Notes so 
owned which have been pledged in good faith shall not be disregarded if the 
pledgee establishes to the satisfaction of the Trustee such 



                                   -29-


<PAGE>

pledgee's right so to act with respect to the Notes and that the pledgee is 
not the Company or an Affiliate of the Company or any of their agents.

     SECTION 2.09.  TEMPORARY NOTES.  Pending the preparation of definitive 
Notes, the Company may execute, and the Trustee shall authenticate, temporary 
notes ("Temporary Notes") which are printed, lithographed, or otherwise 
produced, substantially of the tenor of the definitive Notes in lieu of which 
they are issued and with such appropriate insertions, omissions, 
substitutions and other variations.

     If Temporary Notes are issued, the Company shall cause definitive Notes 
to be prepared without unreasonable delay.  After the preparation of 
definitive Notes, the Temporary Notes shall be exchangeable for definitive 
Notes upon surrender of the Temporary Notes to the Trustee, without charge to 
the Holder.  Until so exchanged, Temporary Notes will evidence the same debt 
and will be entitled to the same benefits under this Indenture as the 
definitive Notes in lieu of which they have been issued.

     SECTION 2.10. CANCELLATION.  The Company at any time may deliver Notes 
to the Trustee for cancellation.  The Registrar and the Paying Agent shall 
forward to the Trustee any Notes surrendered to them for registration of 
transfer, exchange, purchase or payment.  The Trustee shall cancel all Notes 
surrendered for registration of transfer, exchange, purchase, payment or 
cancellation and shall return such canceled Notes to the Company.  The Company
may not issue new Notes to replace Notes it has redeemed or paid or that have
been delivered to the Trustee for cancellation.

     SECTION 2.11. PAYMENT OF INTEREST; INTEREST RIGHTS PRESERVED.  Interest 
on any Note which is payable, and is punctually paid or duly provided for, on 
any Interest Payment Date shall be paid to the Person in whose name such Note 
is registered at the close of business on the Record Date for such interest 
payment, which shall be the ____________ __, or ____________ __ (whether or not 
a Business Day) immediately preceding such Interest Payment Date.

     Any interest on any Note which is payable, but is not punctually paid or 
duly provided for, on any Interest Payment Date (herein called "Defaulted 
Interest") shall forthwith cease to be payable to the registered Holder on 
the relevant Record Date, and, except as hereinafter provided, such Defaulted 
Interest, and any interest payable on such Defaulted Interest, may be paid by 
the Company, at its election, as provided in clause (a) or (b) below:

          (a)  The Company may elect to make payment of any Defaulted Interest,
     and any interest payable on such Defaulted Interest, to the Persons in 
     whose names the Notes are registered at the close of business on a Special
     Record Date for the payment of such Defaulted Interest, which shall be 
     fixed in the following manner.  The Company shall notify the Trustee in 
     writing of the amount of Defaulted Interest proposed to be paid on the 
     Notes and the date of the proposed payment, and at the same time the 
     Company shall deposit with the Trustee an amount of money equal to the 
     aggregate amount proposed to be paid in respect of such Defaulted Interest
     or shall make arrangements satisfactory to the Trustee for such deposit 
     prior to the date of the proposed 



                                   -30-


<PAGE>

     payment, such money when deposited to be held in trust for the benefit of
     the Persons entitled to such Defaulted Interest as provided in this Clause.
     Thereupon the Trustee shall fix a Special Record Date for the payment of 
     such Defaulted Interest which shall be not more than 15 calendar days and 
     not less than 10 calendar days prior to the date of the proposed payment
     and not less than 10 calendar days after the receipt by the Trustee of the
     notice of the proposed payment.  The Trustee shall promptly notify the 
     Company of such Special Record Date and, in the name and at the expense of
     the Company, shall cause notice of the proposed payment of such Defaulted 
     Interest and the Special Record Date therefor to be sent, first class mail,
     postage prepaid, to each Holder at such Holder's address as it appears in 
     the Security Register, not less than 10 calendar days prior to such Special
     Record Date.  Notice of the proposed payment of such Defaulted Interest and
     the Special Record Date therefor having been mailed as aforesaid, such 
     Defaulted Interest shall be paid to the Persons in whose names the Notes 
     are registered at the close of business on such Special Record Date and 
     shall no longer be payable pursuant to the following clause (b).

          (b)  The Company may make payment of any Defaulted Interest, and any
     interest payable on such Defaulted Interest, on the Notes in any other 
     lawful manner not inconsistent with the requirements of any securities 
     exchange on which the Notes may be listed, and upon such notice as may be
     required by such exchange, if, after notice given by the Company to the 
     Trustee of the proposed payment pursuant to this clause, such manner of
     payment shall be deemed practicable by the Trustee.

     Subject to the foregoing provisions of this Section 2.11, each Note 
delivered under this Indenture upon registration of transfer of, or in exchange
for, or in lieu of, any other Note, shall carry the rights to interest accrued
and unpaid, and to accrue, which were carried by such other Note.

     SECTION 2.12.  AUTHORIZED DENOMINATIONS.  The Notes shall be issuable in 
denominations of $1,000 and any integral multiple thereof.

     SECTION 2.13.  COMPUTATION OF INTEREST.  Interest on the Notes shall be 
computed on the basis of a 360-day year of twelve 30-day months.

     SECTION 2.14.  PERSONS DEEMED OWNERS.  Prior to the due presentation for 
registration of transfer of any Note, the Company, the Trustee, the Paying 
Agent, the Registrar or any co-registrar may deem and treat the person in 
whose name such Note is registered as the absolute owner of such Note for the 
purpose of receiving payment of principal of, premium, if any, and interest 
on such Note and for all other purposes whatsoever, whether or not such Note 
is overdue, and none of the Company, the Trustee, the Paying Agent, the 
Registrar or any co-Registrar shall be affected by notice to the contrary.

     SECTION 2.15.  CUSIP NUMBERS.  The Company, in issuing the Notes, may 
use a "CUSIP" number for each series of Notes and, if so, the Trustee shall 
use the relevant CUSIP number in any notices to Holders as a convenience to 
such Holders; provided that any such notice may state that no 



                                   -31-


<PAGE>

representation is made as to the correctness or accuracy of the CUSIP number 
printed in the notice or on the Notes and that reliance may be placed only on 
the other identification numbers printed on the Notes.  The Company shall 
promptly notify the Trustee of any change in any CUSIP number used.

                                 ARTICLE III
                                 REDEMPTION

     SECTION 3.01.  NOTICE TO TRUSTEE.  If the Company elects to redeem Notes
pursuant to paragraph five of the Notes, it shall notify the Trustee in 
writing of the Redemption Date and the principal amount of Notes to be 
redeemed.  The Company shall give each such notice to the Trustee at least 30 
calendar days prior to the Redemption Date unless the Trustee consents to a 
shorter period.  Such notice shall be accompanied by an Officers' Certificate 
and an Opinion of Counsel from the Company to the effect that such redemption 
will comply with any conditions to such redemption set forth herein and in 
the Notes.

     SECTION 3.02.  SELECTION OF NOTES TO BE REDEEMED.  If less than all the 
Notes are to be redeemed at any time, the Trustee shall select the Notes to 
be redeemed on a pro rata basis, provided that the Trustee may select for 
redemption in part only Notes in denominations larger than $1,000.  In 
selecting Notes to be redeemed pursuant to this Section 3.02, the Trustee 
shall make such adjustments, reallocations and eliminations as it shall deem 
proper so that the principal amount of each Note to be redeemed shall be 
$1,000 or an integral multiple thereof, by increasing, decreasing or 
eliminating any amount less than $1,000 which would be allocable to any 
Holder.  If the Notes to be redeemed are Certificated Notes, the Certificated 
Notes to be redeemed shall be selected by the Trustee by prorating, as nearly 
as may be, the principal amount of Certificated Notes to be redeemed among 
the Holders of Certificated Notes registered in their respective names.  
Provisions of this Indenture that apply to Notes called for redemption also 
apply to portions of Notes called for redemption.  The Trustee shall notify 
the Company promptly of the Notes or portions of Notes to be redeemed. 

     SECTION 3.03.  NOTICE OF REDEMPTION.  At least 30 calendar days but not 
more than 60 calendar days before a Redemption Date, the Company shall send a 
notice of redemption, first class mail, postage prepaid, to Holders of Notes 
to be redeemed at the addresses of such Holders as they appear in the Security
Register.

     The notice shall identify the Notes to be redeemed (including CUSIP number)
and shall state:

          (a)  the Redemption Date;

          (b)  the Redemption Price (and shall specify the portion of such 
     Redemption Price that constitutes the amount of accrued and unpaid interest
     to be paid, if any);

          (c)  the name and address of the Paying Agent;



                                   -32-


<PAGE>

          (d)  that the Notes called for redemption must be surrendered to the
     Paying Agent to collect the Redemption Price;

          (e)  if any Global Note is being redeemed in part, the portion of the
     principal amount of such Note to be redeemed and that, after the Redemption
     Date, the Global Note, with a notation on Schedule A thereof adjusting the
     principal amount thereof to be equal to the unredeemed portion, will be 
     returned to the Holder thereof;

          (f)  if any Certificated Note is being redeemed in part, the portion
     of the principal amount of such Note to be redeemed and that, after the 
     Redemption Date, a new Certificated Note or Certificated Notes in principal
     amount equal to the unredeemed portion will be issued;

          (g)  if fewer than all the outstanding Notes are to be redeemed, the
     identification and principal amounts of the particular Notes to be 
     redeemed;

          (h)  that, unless the Company defaults in making the redemption 
     payment, interest on the Notes (or portions thereof) called for redemption
     shall cease and such Notes (or portions thereof) shall cease to accrue 
     interest on and after the Redemption Date;

          (i)  the paragraph of the Notes pursuant to which the Notes are being
     called for redemption; and

          (j)  any other information necessary to enable Holders to comply with
     the notice of redemption.

     At the Company's request, the Trustee shall give the notice of redemption
in the Company's name and at the Company's expense.  In such event, the Company
shall provide the Trustee with the information required by this Section 3.03 
in a timely manner.

     SECTION 3.04.  EFFECT OF NOTICE OF REDEMPTION.  Once notice of redemption
is mailed, Notes called for redemption shall become due and payable on the 
Redemption Date and at the Redemption Price stated in such notice.  Upon 
surrender to the Paying Agent, such Notes shall be paid at the Redemption 
Price stated in such notice.  Failure to give notice or any defect in the notice
to any Holder shall not affect the validity of the notice to any other Holder.

     SECTION 3.05.  DEPOSIT OF REDEMPTION PRICE.  On or prior to 10:00 a.m., 
New York City time, on each Redemption Date, the Company shall deposit with the
Paying Agent (or, if the Company, one of its Subsidiaries or any of their 
Affiliates is the Paying Agent, the Paying Agent shall segregate and hold in 
trust for the benefit of the Holders) money, in federal or other immediately 
available funds, sufficient to pay the Redemption Price on all Notes to be 
redeemed on that date other than Notes or portions of Notes called for 
redemption on such date which have been delivered by the Company to the 
Trustee for cancellation.



                                   -33-


<PAGE>

     So long as the Company complies with the preceding paragraph and the 
other provisions of this Article III, interest on the Notes or portions 
thereof to be redeemed on the applicable Redemption Date shall cease to 
accrue from and after such date and such Notes or  portions thereof shall be 
deemed not to be entitled to any benefit under this Indenture except to 
receive payment of the Redemption Price on the Redemption Date. If any Note 
called for redemption shall not be so paid upon surrender for redemption, 
then, from the Redemption Date until such Redemption Price is paid, interest 
shall be paid on the unpaid principal and premium and, to the extent permitted
by law, on any accrued but unpaid interest thereon, in each case at the rate
prescribed therefor by such Notes.

     SECTION 3.06.  NOTES REDEEMED IN PART.  Upon surrender and cancellation 
of a Certificated Note that is redeemed in part, the Company shall issue and 
the Trustee shall authenticate and make available for delivery to the 
surrendering Holder (at the Company's expense) a new Certificated Note equal 
in principal amount to the unredeemed portion of the Certificated Note 
surrendered and canceled, PROVIDED that each such Certificated Note shall be 
in a principal amount of $1,000 or an integral multiple thereof.

     Upon surrender of a Global Note that is redeemed in part, the Paying 
Agent shall forward such Global Note to the Trustee who shall make a notation 
on Schedule A thereof to reduce the principal amount of such Global Note to 
an amount equal to the unredeemed portion of such Global Note, as provided in 
Section 2.05(c) hereof.


                                  ARTICLE IV
                                   COVENANTS

     SECTION 4.01.  PAYMENT OF NOTES.  The Company shall promptly pay the 
principal of, premium, if any, and interest on, the Notes on the dates and in 
the manner provided in the Notes and in this Indenture. Principal, premium 
and interest shall be considered paid on the date due if, on such date, the 
Trustee or the Paying Agent holds in accordance with this Indenture money 
sufficient to pay all principal, premium and interest then due.

     To the extent lawful, the Company shall pay interest on overdue 
principal, overdue premium, and Defaulted Interest (without regard to any 
applicable grace period), at the interest rate borne on the Notes. The 
Company's obligation pursuant to the previous sentence shall apply whether 
such overdue amount is due at its Stated Maturity, as a result of the Company's
obligations pursuant to Section 3.05, Section 4.07 or Section 4.08 hereof, or
otherwise.

     SECTION 4.02.   MAINTENANCE OF OFFICE OR AGENCY.  The Company shall 
maintain in the Borough of Manhattan, The City of New York, an office or 
agency where Notes may be presented or surrendered for payment, where Notes 
may be surrendered for registration of transfer or exchange and where notices 
and demands to or upon the Company in respect of the Notes and this Indenture 
may be served, which office shall be initially the office of State Street 
Bank and Trust Company, National Association, 61 Broadway, New York, New York 
10006, Concourse Level, Corporate 



                                   -34-


<PAGE>

Trust Window.  The Company shall give prompt written notice to the Trustee of 
any change in the location of such office or agency.  If at any time the 
Company shall fail to maintain any such required office or agency or shall 
fail to furnish the Trustee with the address thereof, such presentations, 
surrenders, notices and demands may be made or served at the Corporate Trust 
Office of the Trustee, and the Company hereby appoints the Trustee its agent 
to receive all presentations, surrenders, notices and demands.

     The Company may also from time to time designate one or more other 
offices or agencies (in or outside of The City of New York) where the Notes 
may be presented or surrendered for any or all of such purposes, and may from 
time to time rescind such designations; provided that no such designation or 
rescission shall in any manner relieve the Company of its obligation to 
maintain an office or agency in The City of New York, for such purposes.  The 
Company shall give prompt written notice to the Trustee of any such 
designation and any change in the location of any such other office or agency.

     SECTION 4.03.  MONEY FOR THE NOTE PAYMENTS TO BE HELD IN TRUST.  If the 
Company, any Subsidiary of the Company or any of their respective Affiliates 
shall at any time act as Paying Agent with respect to the Notes, such Paying 
Agent shall, on or before each due date of the principal of (and premium, if 
any) or interest on any of the Notes, segregate and hold in trust for the 
benefit of the Persons entitled thereto money sufficient to pay the principal 
(and premium, if any) or interest so becoming due until such money shall be 
paid to such Persons or otherwise disposed of as herein provided, and shall 
promptly notify the Trustee of its action or failure so to act.

     Whenever the Company shall have one or more Paying Agents with respect 
to the Notes, it shall, prior to or on each due date of the principal of (and 
premium, if any) or interest on any of the Notes, deposit with a Paying Agent 
a sum sufficient to pay the principal (and premium, if any) or interest so 
becoming due, such sum to be held in trust for the benefit of the Persons 
entitled to such principal, premium or interest and (unless such Paying Agent 
is the Trustee) the Paying Agent shall promptly notify the Trustee of the 
Company's action or failure so to act.

     SECTION 4.04.  CORPORATE EXISTENCE.  Subject to the provisions of 
Article V hereof, the Company shall do or cause to be done all things 
necessary to preserve and keep in full force and effect the corporate 
existence, rights (charter and statutory) and franchises of the Company and 
each of its Subsidiaries; PROVIDED that the Company and any such Subsidiary 
shall not be required to preserve the corporate existence of any such 
Subsidiary or any such right or franchise if the Board of Directors of the 
Company shall determine that the preservation thereof is no longer desirable 
in the conduct of the business of the Company and that the loss thereof is 
not disadvantageous in any material respect to the Holders of Notes.

     SECTION 4.05.  MAINTENANCE OF PROPERTY.  The Company shall cause all 
Property used or useful in the conduct of its business or the business of any 
of its Subsidiaries to be maintained and kept in good condition, repair and 
working order and supplied with all necessary equipment and shall cause to be 
made all necessary repairs, renewals, replacements, betterments and improvements




                                   -35-


<PAGE>

thereof, all as, in the judgment of the Company, may be necessary so that the 
business carried on in connection therewith may be properly and advantageously
conducted at all times; provided that nothing in this Section 4.05 shall prevent
the Company from discontinuing the operation or maintenance of any of such 
Property if such discontinuance is, in the judgment of the Company, desirable in
the conduct of its business or the business of any of its Subsidiaries and not 
disadvantageous in any material respect to the Holders of Notes.

     SECTION 4.06.   PAYMENT OF TAXES AND OTHER CLAIMS.  The Company shall pay 
or discharge or cause to be paid or discharged, before the same shall become 
delinquent, (a) all taxes, assessments and governmental charges levied or 
imposed upon the Company or any of its Subsidiaries or upon the income, 
profits or Property of the Company or any of its Subsidiaries and (b) all 
lawful claims for labor, materials and supplies which, if unpaid, might by 
law become a Lien upon the Property of the Company or any of its Subsidiaries;
PROVIDED that the Company shall not be required to pay or discharge or cause to
be paid or discharged any such tax, assessment, charge or claim whose amount,
applicability or validity is being contested in good faith by appropriate 
proceedings upon stay of execution or the enforcement thereof and for which 
adequate reserves in accordance with GAAP or other appropriate provision has 
been made.

     SECTION 4.07.  REPURCHASE AT THE OPTION OF HOLDERS UPON A CHANGE OF 
CONTROL. (a)  Upon the occurrence of a Change of Control, each Holder of 
Notes shall have the right to require the Company to purchase such Holder's 
Notes, in whole or in part, in a principal amount that is an integral multiple
of $1,000, pursuant to the offer described in Section 4.07(b) hereof (the 
"Change of Control Offer") at a purchase price (the "Change of Control Purchase
Price") in cash equal to 101% of the aggregate principal amount thereof plus 
accrued and unpaid interest thereon to the date of purchase (the "Change of 
Control Payment Date").

     (b)  Within 30 calendar days after the date of any Change of Control, the
Company, or the Trustee at the request and expense of the Company, shall send 
to each Holder by first class mail, postage prepaid, a notice prepared by the 
Company describing the transaction or transactions that constitute the Change 
of Control and stating:

          (i)   that a Change of Control has occurred and a Change of Control 
     Offer is being made pursuant to this Section 4.07, and that all Notes that
     are timely tendered will be accepted for payment;

          (ii)  the Change of Control Purchase Price, and the Change of Control
     Payment Date, which date shall be a Business Day no earlier than 30 
     calendar days nor later than 60 calendar days subsequent to the date such 
     notice is mailed;

          (iii) that any Notes or portions thereof not tendered or accepted for
     payment will continue to accrue interest;



                                   -36-


<PAGE>

          (iv)  that, unless the Company defaults in the payment of the Change 
     of Control Purchase Price with respect thereto, all Notes or portions 
     thereof accepted for payment pursuant to the Change of Control Offer shall
     cease to accrue interest from and after the Change of Control Payment Date;

          (v)   that any Holder electing to have any Notes or portions thereof 
     purchased pursuant to a Change of Control Offer will be required to 
     surrender such Notes, with the form entitled "Option of Holder to Elect 
     Purchase" on the reverse of such Notes completed, to the Paying Agent at 
     the address specified in the notice, prior to the close of business on the
     third Business Day preceding the Change of Control Payment Date;

          (vi)  that any Holder shall be entitled to withdraw such election if
     the Paying Agent receives, not later than the close of business on the 
     second Business Day preceding the Change of Control Payment Date, a 
     facsimile transmission or letter, setting forth the name of the Holder,
     the principal amount of Notes delivered for purchase, and a statement that
     such Holder is withdrawing such Holder's election to have such Notes or 
     portions thereof purchased pursuant to the Change of Control Offer;

          (vii) that any Holder electing to have Notes purchased pursuant to the
     Change of Control Offer must specify the principal amount that is being 
     tendered for purchase, which principal amount must be $1,000 or an integral
     multiple thereof;

          (viii)  if Certificated Notes have been issued pursuant to Section 
     2.06, that any Holder of Certificated Notes whose Certificated Notes are 
     being purchased only in part will be issued new Certificated Notes equal
     in principal amount to the unpurchased portion of the Certificated Note or
     Notes surrendered, which unpurchased portion will be equal in principal 
     amount to $1,000 or an integral multiple thereof;

          (ix)  that the Trustee will return to the Holder of a Global Note 
     that is being purchased in part, such Global Note with a notation on 
     Schedule A thereof adjusting the principal amount thereof to be equal
     to the unpurchased portion of such Global Note; and

          (x)   any other information necessary to enable any Holder to tender
     Notes and to have such Notes purchased pursuant to this Section 4.07.

     (c)   On the Change of Control Payment Date, the Company shall (1) 
accept for payment all Notes or portions thereof properly tendered pursuant 
to the Change of Control Offer, (2) irrevocably deposit with the Paying 
Agent, by 10:00 a.m., New York City time, on such date, in immediately 
available funds, an amount equal to the Change of Control Purchase Price in 
respect of all Notes or portions thereof so accepted and (3) deliver or cause 
to be delivered to the Trustee the Notes so accepted together with an 
Officers' Certificate stating the aggregate principal amount of Notes or 
portions thereof being purchased by the Company.  The Paying Agent shall 
promptly send by first class mail, postage prepaid, to each Holder of Notes 
or portions thereof so accepted for

                                   -37-


<PAGE>

payment the Change of Control Purchase Price for such Notes or portions 
thereof.  The Company shall publicly announce the results of the Change of 
Control Offer on or as soon as practicable after the Change of Control 
Payment Date.  For purposes of this Section 4.07, the Trustee shall act as 
the Paying Agent.

     (d)   Upon surrender and cancellation of a Certificated Note that is 
purchased in part pursuant to the Change of Control Offer, the Company shall 
promptly issue and the Trustee  shall authenticate and deliver to the 
surrendering Holder of such Certificated Note a new Certificated Note equal 
in principal amount to the unpurchased portion of such surrendered 
Certificated Note; provided that each such new Certificated Note shall be in 
a principal amount of $1,000 or an integral multiple thereof.

     Upon surrender of a Global Note that is purchased in part pursuant to a 
Change of Control Offer, the Paying Agent shall forward such Global Note to 
the Trustee who shall make a notation on Schedule A thereof to reduce the 
principal amount of such Global Note to an amount equal to the unpurchased 
portion of such Global Note, as provided in Section 2.05(c) hereof.

     (e)  The Company shall comply with the requirements of Section 14(e) 
under the Exchange Act and any other securities laws or regulations, to the 
extent such laws and regulations are applicable, in connection with the 
purchase of Notes pursuant to a Change of Control Offer.

     (f)  Prior to complying with the provisions of this Section 4.07, but in 
any event within 30 days following a Change of Control, the Company shall 
either repay all outstanding Senior Indebtedness or obtain the requisite 
consents, if any, under all agreements governing outstanding Senior 
Indebtedness to permit the repurchase of Notes required by this Section 4.07.

   
     SECTION 4.08.  LIMITATION ON ASSET SALES. (a) The Company shall not 
directly or indirectly engage in an Asset Sale of any Principal Properties to 
any Subsidiary other than a Subsidiary Guarantor. 
    

     (b)  The Company shall not, and shall not permit any of its Subsidiaries, 
directly or indirectly, to, engage in an Asset Sale unless:

          (i)  the Company (or such Subsidiary) receives consideration at the 
     time of such Asset Sale at least equal to the fair market value, and in the
     case of a lease of assets under which the Company or any of its 
     Subsidiaries is the lessor, a lease providing for rent and other conditions
     which are no less favorable to the Company (or such Subsidiary) in any 
     material respect than the then prevailing market conditions (evidenced in 
     each case by a resolution of the Board of Directors of such Person set 
     forth in an Officers' Certificate of such Person delivered to the Trustee)
     of the assets sold or otherwise disposed of, and

          (ii)  at least 85% (100% in the case of such lease payments) of the 
     consideration therefor received by the Company or such Subsidiary is in the
     form of cash or Cash Equivalents or properties used in the Oil and Gas 
     Business of the Company and its Subsidiaries.

   
     (c)  The Company may apply Net Proceeds of an Asset Sale, at its option, 
(i) to permanently reduce Senior Indebtedness other than Senior Revolving 
Indebtedness, (ii) to permanently reduce Senior Revolving Indebtedness (and to 
correspondingly reduce commitments 
    


                                   -38-


<PAGE>

   
with respect thereto), or (iii) to invest in properties and assets that will be 
used in the Oil and Gas Business of the Company and its Subsidiaries. Pending 
the final application of any such Net Proceeds, the Company may temporarily 
reduce Senior Revolving Indebtedness or otherwise invest such Net Proceeds in 
any manner that is not prohibited by this Indenture.
    

     Any Net Proceeds from Asset Sales that are not applied within 270 days 
after the consummation of an Asset Sale as provided in the preceding paragraph
will be deemed to constitute "Excess Proceeds."

   
     (d)  When the aggregate amount of Excess Proceeds exceeds $5.0 million, 
the Company will be required to make an offer to all Holders of Notes, as 
described in Section 4.08(e) hereof (an "Asset Sale Offer"), to purchase from 
all Holders, on a pro rata basis, Notes in an aggregate principal amount equal
to the maximum principal amount of Notes that may be purchased out of the 
then existing Excess Proceeds, at a purchase price (the "Asset Sale Purchase 
Price") in cash in an amount equal to 100% of the principal amount thereof 
plus accrued and unpaid interest thereon to the date of purchase.

     (e)  Within 30 calendar days after the date the amount of Excess Proceeds
exceeds $5.0 million, the Company, or the Trustee at the request and expense of
the Company, shall send to each Holder by first class mail, postage prepaid, a
notice prepared by the Company stating:
    

          (i)   that an Asset Sale Offer is being made pursuant to this Section
     4.08, and that are Notes that are timely tendered will be accepted for 
     payment, subject to proration in the event the amount of Excess Proceeds is
     less than the aggregate Asset Sale Purchase Price of all Notes timely 
     tendered pursuant to the Asset Sale Offer;

          (ii)  the Asset Sale Purchase Price, the amount of Excess Proceeds 
     that are available to be applied to purchase tendered Notes, and the date
     Notes are to be purchased pursuant to the Asset Sale Offer (the "Asset 
     Sale Payment Date"), which date shall be a Business Day no earlier than 
     30 calendar days nor later than 60 calendar days subsequent to the date
     such notice is mailed;

          (iii)  that any Notes or portions thereof not tendered or accepted
     for payment will continue to accrue interest;

          (iv)  that, unless the Company defaults in the payment of the Asset 
     Sale Purchase Price with respect thereto, all Notes or portions thereof
     accepted for payment pursuant to the Asset Sale Offer shall cease to 
     accrue interest from and after the Asset Sale Payment Date;

          (v)   that any Holder electing to have any Notes or portions thereof
     purchased pursuant to the Asset Sale Offer will be required to surrender 
     such Notes, with the form entitled "Option of Holder to Elect Purchase" on
     the reverse of such Notes completed, to the Paying 



                                   -39-


<PAGE>

     Agent at the address specified in the notice, prior to the close of 
     business on the third Business Day preceding the Asset Sale Payment 
     Date;

          (vi)  that any Holder shall be entitled to withdraw such election if
     the Paying Agent receives, not later than the close of business on the 
     second Business Day preceding the Asset Sale Payment Date, a facsimile 
     transmission or letter, setting forth the name of the Holder, the principal
     amount of Notes delivered for purchase, and a statement that such Holder is
     withdrawing such Holder's election to have such Notes or portions thereof
     purchased pursuant to the Asset Sale Offer;

          (vii) that any Holder electing to have Notes purchased pursuant to the
     Asset Sale Offer must specify the principal amount that is being tendered
     for purchase, which principal amount must be $1,000 or an integral multiple
     thereof;

          (viii) if Certificated Notes have been issued pursuant to Section 
     2.06, that any Holder of Certificated Notes whose Certificated Notes are
     being purchased only in part will be issued new Certificated Notes equal 
     in principal amount to the unpurchased portion of the Certificated Note or
     Notes surrendered, which unpurchased portion will be equal in principal 
     amount to $1,000 or an integral multiple thereof;

          (ix)  that the Trustee will return to the Holder of a Global Note 
     that is being purchased in part, such Global Note with a notation on 
     Schedule A thereof adjusting the principal amount thereof to be equal to
     the unpurchased portion of such Global Note; and

          (x)   any other information necessary to enable any Holder to tender
     Notes and to have such Notes purchased pursuant to this Section 4.08.

   
     (f)  If the aggregate principal amount of the Notes surrendered by 
Holders exceeds the amount of Excess Proceeds as indicated in the notice 
required by Section 4.08(e) hereof, the Trustee shall select the Notes to be 
purchased on a PRO RATA basis based on the principal amount of the Notes 
tendered, with such adjustments as may be deemed appropriate by the Trustee, 
so that only Notes in denominations of $1,000 or integral multiples thereof 
shall be purchased.

     (g)  On the Asset Sale Payment Date, the Company shall (i) accept for 
payment any Notes or portions thereof properly tendered and selected for 
purchase pursuant to the Asset Sale Offer and Section 4.08(f) hereof; (ii) 
irrevocably deposit with the Paying Agent, by 10:00 a.m., New York City time, 
on such date, in immediately available funds, an amount equal to the Asset 
Sale Purchase Price in respect of all Notes or portions thereof so accepted; 
and (iii) deliver, or cause to be delivered, to the Trustee the Notes so 
accepted together with an Officers' Certificate listing the Notes or portions 
thereof tendered to the Company and accepted for payment.  The Paying Agent 
shall promptly send by first class mail, postage prepaid, to each Holder of 
Notes or portions thereof so accepted for payment the Asset Sale Purchase 
Price for such Notes or portions thereof.  The Company shall 
    



                                   -40-


<PAGE>

publicly announce the results of the Asset Sale Offer on or as soon as 
practicable after the Asset Sale Payment Date.  For purposes of this Section 
4.08, the Trustee shall act as the Paying Agent.

   
     (h)  Upon surrender and cancellation of a Certificated Note that is 
purchased in part, the Company shall promptly issue and the Trustee shall 
authenticate and deliver to the surrendering Holder of such Certificated Note 
a new Certificated Note equal in principal amount to the unpurchased portion 
of such surrendered Certificated Note; PROVIDED that each such new 
Certificated Note shall be in a principal amount of $1,000 or an integral 
multiple thereof.
    

     Upon surrender of a Global Note that is purchased in part pursuant to an 
Asset Sale Offer, the Paying Agent shall forward such Global Note to the 
Trustee who shall make a notation on Schedule A thereof to reduce the 
principal amount of such Global Note to an amount equal to the unpurchased 
portion of such Global Note, as provided in Section 2.05(c) hereof.

   
     (i)  Upon completion of an Asset Sale Offer (including payment of the 
Asset Sale Purchase Price for accepted Notes), any surplus Excess Proceeds 
that were the subject of such offer shall cease to be Excess Proceeds, and 
the Company may then use such amounts for general corporate purposes.

     (j)  The Company shall comply with the requirements of Section 14(e) 
under the Exchange Act and any other securities laws or regulations, to the 
extent such laws and regulations are applicable, in connection with the 
purchase of Notes pursuant to an Asset Sale Offer.

     SECTION 4.09.   OWNERSHIP OF CAPITAL STOCK.  The Company shall not 
permit any Person (other than the Company or any Wholly Owned Subsidiary of 
the Company) to own any Capital Stock of any Subsidiary of the Company, and 
shall not permit any Subsidiary of the Company to issue Capital Stock (except 
to the Company or to a Wholly Owned Subsidiary of the Company), in each 
case except (a) directors' qualifying shares, (b) Capital Stock issued 
prior to the time such Person becomes a Subsidiary of the Company, (c) if 
such Subsidiary merges with and into another Subsidiary, (d) if another 
Subsidiary merges with and into such Subsidiary, (e) if such Subsidiary 
ceases to be a Subsidiary (as a result of the sale of 100% of the shares of 
such Subsidiary, the Net Proceeds from which are applied in accordance with 
Section 4.08 hereof), or (f) Capital Stock of a Subsidiary organized in a 
foreign jurisdiction required to be issued to, or owned by, the government of 
such foreign jurisdiction or individual or corporate citizens of such foreign 
jurisdiction in order for such Subsidiary to transact business in such 
foreign jurisdiction.
    
                                   -41-

<PAGE>


     SECTION 4.10.  UNRESTRICTED SUBSIDIARIES.  The Board of Directors of the 
Company may designate any of its Subsidiaries as Unrestricted Subsidiaries.  
A Subsidiary may only be so designated if (i) immediately after giving effect 
to such designation no Default or Event of Default exists, (ii) the Company 
would, at the time of such designation and after giving pro forma effect 
thereto as if such designation had occurred at the beginning of the 
applicable four-quarter period, have been permitted to incur at least $1.00 
of additional Indebtedness pursuant to the Consolidated Interest Coverage 
Ratio and the Adjusted Consolidated Net Tangible Assets to Consolidated 
Indebtedness Ratio tests set forth in Section 4.12(a) hereof, and (iii) after 
the date of this Indenture and prior to such designation, no assets of the 
Company or of any Subsidiary of the Company (including, without limitation, 
Capital Stock of any such Subsidiary) shall have been transferred, directly 
or indirectly, to any Unrestricted Subsidiary or any of its Subsidiaries, 
other than assets transferred in the ordinary course of business and on terms 
that are no less favorable to the Company or the relevant Subsidiary than 
those that would have been obtained in a comparable transaction by the 
Company or such Subsidiary with an unrelated Person.  Any such designation by 
the Board of Directors of the Company shall be evidenced to the Trustee by 
filing with the Trustee a certified copy of the Board Resolution of the 
Company giving effect to such designation and an Officers' Certificate of the 
Company certifying that such designation complied with the foregoing 
conditions.

   
     Any subsidiary of the Company shall continue to be an Unrestricted 
Subsidiary only if it (a) has no Indebtedness other than Non-Recourse 
Indebtedness; (b) is a Person with respect to which neither the Company nor 
any of its Subsidiaries has any direct or indirect obligation (x) to 
subscribe for additional Equity Interests or (y) to maintain or preserve such 
Person's financial condition or to cause such Person to achieve any specified 
levels of operating results; and (c) has not guaranteed or otherwise directly 
or indirectly provided credit support for any Indebtedness of the Company or 
any of its Subsidiaries.  If, at any time, any Unrestricted Subsidiary fails 
to meet the foregoing requirements, such Unrestricted Subsidiary shall 
thereafter cease to be an Unrestricted Subsidiary for purposes of this 
Indenture, such Unrestricted Subsidiary shall execute and deliver a 
supplemental indenture pursuant to which such Person guarantees the payment 
of the Notes on the same terms and conditions as the Subsidiary Guarantees by 
the Subsidiary Guarantors  and any Indebtedness of such Unrestricted 
Subsidiary shall be deemed to be incurred by a Subsidiary of the Company as 
of such date.
    

     The Board of Directors of the Company may at any time designate any 
Subsidiary, if previously designated as Unrestricted Subsidiaries, to be a 
Subsidiary; provided that such designation shall be deemed to be an 
incurrence of Indebtedness by a Subsidiary of the Company of any outstanding 
Indebtedness of such Subsidiary and such designation shall only be permitted 
if (i) such Indebtedness is permitted under the covenant described under 
Section 4.12 hereof, (ii) no Default or Event of Default would be in 
existence following such designation and (iii) such Subsidiary shall execute 
and deliver a supplemental indenture pursuant to which such Person guarantees 
the payment of the Notes on the same terms and conditions as the Subsidiary 
Guarantees by the Subsidiary Guarantors.


                                     -42-

<PAGE>

     SECTION 4.11.  RESTRICTED PAYMENTS.  The Company shall not, and shall 
not permit any of its Subsidiaries to, directly or indirectly: (i) declare or 
pay any dividend or make any distribution on account of the Company's or any 
of its Subsidiaries' Equity Interests, other than dividends or distributions 
payable in Equity Interests (other than Disqualified Stock) of the Company or 
dividends or distributions payable to the Company or any Wholly Owned 
Subsidiary of the Company; (ii) purchase, redeem or otherwise acquire or 
retire for value any Equity Interests of the Company or any Subsidiary or 
Unrestricted Subsidiary or other Affiliate of the Company (other than Equity 
Interests of the Company, any Subsidiary or Unrestricted Subsidiary owned by 
any Wholly Owned Subsidiary of the Company); (iii) make any principal payment 
on, or purchase, redeem, defease or otherwise acquire or retire for value any 
PARI PASSU Indebtedness prior to a scheduled mandatory sinking fund payment 
date or maturity date, or (iv) make any Restricted Investment (all such 
payments and other actions set forth in clauses (i) through (iv) above being 
collectively referred to as "Restricted Payments"), unless, at the time of 
and after giving effect to such Restricted Payment:

          (a)  no Default or Event of Default shall have occurred and be 
     continuing or would occur as a consequence thereof;

          (b)  the Company would, at the time of such Restricted Payment and 
     after giving pro forma effect thereto as if such Restricted Payment had 
     been made at the beginning of the applicable four-quarter period, have 
     been permitted to incur at least $1.00 of additional Indebtedness 
     pursuant to the Consolidated Interest Coverage Ratio and the Adjusted 
     Consolidated Net Tangible Assets to Consolidated Indebtedness Ratio 
     tests set forth under Section 4.12(a); and

   
          (c)  such Restricted Payment, together with the aggregate of all 
     other Restricted Payments made by the Company and its Subsidiaries on or 
     after the date of this Indenture (excluding Restricted Payments 
     permitted by clauses (ii), (iii), (iv) and (v) of the next succeeding 
     paragraph), is less than the sum of (i) 50% of the Consolidated Net 
     Income of the Company and its Subsidiaries for the period (taken as one 
     accounting period) from the beginning of the first day of the fiscal 
     month during which this Indenture was executed and delivered to the end of
     the Company's most recently ended fiscal quarter for which internal
     financial statements are available at the time of such Restricted Payment
     (or, if such Consolidated Net Income for such period is a deficit, less
     100% of such deficit), plus (ii) 100% of the aggregate net cash proceeds 
     received by the Company as capital contributions to the Company or from 
     the issue or sale after the date of this Indenture of Equity Interests 
     of the Company or of debt securities of the Company that have been 
     converted into such Equity Interests (other than Equity Interests (or 
     convertible debt securities) sold to a Subsidiary or an Unrestricted 
     Subsidiary of the Company and other than Disqualified Stock or 
    

                                     -43-

<PAGE>

     debt securities that have been converted into Disqualified Stock), 
     except for Capital Stock of the Company issued contemporaneously with 
     the issuance of the Notes.

     The foregoing clauses (b) and (c), however, will not prohibit (i) the 
payment of any dividend within 60 days after the date of declaration thereof, 
if at said date of declaration such payment would have complied with the 
provisions of this Indenture; (ii) the payment of any dividend on Equity 
Interests of the Company (other than Disqualified Stock) payable solely in 
shares of Equity Interests of the Company (other than Disqualified Stock);  
(iii) any dividend or other distribution payable from a Subsidiary of the 
Company to the Company or any Wholly Owned Subsidiary; (iv) the making of any 
Restricted Investment in exchange for, or out of the proceeds of, the 
substantially concurrent sale, issuance or exchange (other than to a 
Subsidiary or any Unrestricted Subsidiary of the Company) of Equity Interests 
of the Company (other than Disqualified Stock); PROVIDED, that any net cash 
proceeds that are utilized for any such Restricted Investment shall be 
excluded from clause (c) of the preceding paragraph; (v) the redemption, 
repurchase, retirement or other acquisition of any Equity Interests of the 
Company in exchange for, or out of the proceeds of, the substantially 
concurrent sale, issuance or exchange (other than to a Subsidiary or any 
Unrestricted Subsidiary of the Company) of other Equity Interests of the 
Company (other than any Disqualified Stock); PROVIDED that any net cash 
proceeds that are utilized for any such redemption, repurchase, retirement or 
other acquisition shall be excluded from clause (c) of the preceding 
paragraph; and (vi) the defeasance, redemption or repurchase of any PARI 
PASSU Indebtedness prior to a scheduled mandatory sinking fund payment date 
or maturity date thereof with the net cash proceeds from an incurrence of 
Permitted Refinancing Indebtedness or the substantially concurrent sale 
(other than to a Subsidiary or any Unrestricted Subsidiary of the Company) of 
Equity Interests of the Company (other than Disqualified Stock) or the 
purchase, redemption or acquisition by the Company of any PARI PASSU 
Indebtedness prior to a scheduled mandatory sinking fund payment date or 
maturity date thereof through the issuance in exchange thereof of Equity 
Interests of the Company (other than Disqualified Stock); PROVIDED, that any 
net cash proceeds that are utilized for any such defeasance, redemption or 
repurchase, purchase or acquisition shall be excluded from clause (c) of the 
preceding paragraph.

     The amount of all Restricted Payments (other than cash) shall be the 
fair market value (evidenced by a resolution of the Board of Directors set 
forth in an Officers' Certificate delivered to the Trustee) on the date of 
the Restricted Payment of the asset(s) proposed to be transferred by the 
Company or such Subsidiary, as the case may be, pursuant to the Restricted 
Payment.  Not later than the date of making any Restricted Payment, the 
Company shall deliver to the Trustee an Officers' Certificate of the Company 
stating that such Restricted Payment is permitted and setting forth the basis 
upon which the calculations required by this Section 4.11 were computed, 
which calculations may be based upon the Company's latest available financial 
statements.

     SECTION 4.12.  INCURRENCE OF INDEBTEDNESS AND ISSUANCE OF PREFERRED 
STOCK. (a)  The Company shall not, and shall not permit any of its 
Subsidiaries to, directly or indirectly, create, incur, issue, assume, 
guarantee or otherwise become directly or indirectly liable, contingently or 
otherwise, with respect to (collectively, "incur") any Indebtedness 
(including Acquired Indebtedness) and the Company shall not issue any 
Disqualified Stock and shall not permit any of its Subsidiaries to issue any 
shares of preferred stock; PROVIDED, HOWEVER, that the Company may incur 
Indebtedness (including Acquired Indebtedness) and the Company may issue 
shares of Disqualified Stock if:  (i) the Consolidated Interest Coverage 
Ratio for the Company's most recently ended four full fiscal quarters for 
which internal financial statements are available immediately preceding the 
date on which 


                                     -44-

<PAGE>

   
such additional Indebtedness is incurred or such Disqualified Stock is issued 
would have been at least, during the period from the date of this Indenture 
until the first anniversary thereof, 2.25 to 1, and thereafter, 2.50 to 1, 
determined on a pro forma basis (including a pro forma application of the net 
proceeds therefrom), as if the additional Indebtedness had been incurred, or 
the Disqualified Stock had been issued, as the case may be, at the beginning 
of such four-quarter period; (ii) the Adjusted Consolidated Net Tangible 
Assets would have been at least 150% of Consolidated Indebtedness, determined 
on a pro forma basis (including a pro forma application of the net proceeds 
therefrom) and (iii) no Default or Event of Default shall have occurred and 
be continuing or would occur as a consequence thereof; PROVIDED, that no 
Guarantee may be incurred pursuant to this paragraph, unless the guaranteed 
Indebtedness is incurred by the Company pursuant to this paragraph.
    

     (b)  The foregoing provisions will not apply to:

          (i)  the incurrence by the Company of Indebtedness under the Credit 
     Facility (and the incurrence by Subsidiaries of Guarantees thereof) in 
     an aggregate principal amount at any time outstanding (with letters of 
     credit being deemed to have a principal amount equal to the maximum 
     potential liability of the Company and its Subsidiaries thereunder) not 
     to exceed $50 million, less the aggregate amount of all Net Proceeds of 
     Asset Sales applied to permanently reduce the outstanding amount or the 
     commitments with respect to such Indebtedness pursuant to Section 4.08 
     hereof;

          (ii)   the incurrence by the Company of Indebtedness represented by 
     the Notes and of its Subsidiaries of Indebtedness represented by the 
     Subsidiary Guarantees;

          (iii)   the incurrence by the Company or any of its Subsidiaries of 
     Permitted Refinancing Indebtedness in exchange for, or the net proceeds 
     of which are used to extend, refinance, renew, replace, defease or 
     refund, any Indebtedness described in Section 4.12(b)(ii) hereof;

          (iv)  the incurrence by the Company or any of its Subsidiaries of 
     intercompany Indebtedness between or among the Company and any of its 
     Wholly Owned Subsidiaries or between or among any Wholly Owned 
     Subsidiaries; PROVIDED that, in the case of Indebtedness of the Company, 
     such obligations shall be unsecured and subordinated in case of an event 
     of default in all respects to the Company's obligations pursuant to the 
     Notes; and PROVIDED, HOWEVER, that (i) any subsequent issuance or 
     transfer of Equity Interests that results in any such Indebtedness being 
     held by a Person other than a Wholly Owned Subsidiary of the Company and 
     (ii) any sale or other transfer of any such Indebtedness to a Person 
     that is not either the Company or a Wholly Owned Subsidiary of the 
     Company shall be deemed, in each case, to constitute an incurrence of 
     such Indebtedness by the Company or such Subsidiary, as the case may be;

          (v)  the incurrence by the Company or Hedging Obligations that are 
     incurred for the purpose of fixing or hedging interest rate risk with 
     respect to any floating rate Indebtedness that is permitted by this 
     Indenture to be incurred; PROVIDED that the notional amount 


                                     -45-

<PAGE>

     of such Hedging Obligations does not exceed the principal amount of the 
     Indebtedness to which such Hedging Obligations relate;

   
          (vi)  the incurrence by the Company of Hedging Obligations under 
     commodity hedging and currency exchange agreements; PROVIDED that such 
     agreements were entered into in the ordinary course of business for the 
     purpose of limiting risks that arise in the ordinary course of business; 

          (vii)  the incurrence by the Subsidiaries of Indebtedness in 
     existence on the date of this Indenture listed on Schedule 4.12(b)(viii)
     attached to this Indenture; and

          (viii) the incurrence by the Company and its Subsidiaries of 
     Indebtedness (in addition to Indebtedness permitted by any other clause 
     of this Section 4.12) in an aggregate principal amount at any time 
     outstanding not to exceed $10 million;

PROVIDED that no Subsidiary may incur any Indebtedness other than Indebtedness 
described in Section 4.12(b)(iv) or (vii) unless such Subsidiary shall have 
executed and delivered a Subsidiary Guarantee and such Subsidiary Guarantee 
shall be in full force and effect (except to the extent Section 11.02 hereof 
would result in the release thereof) so long as such Indebtedness remains 
outstanding.
    

     SECTION 4.13.  LIENS.  The Company shall not, and shall not permit any 
of its Subsidiaries to, directly or indirectly, create, incur, assume or 
suffer to exist any Lien (other than Permitted Liens but only to the extent 
securing obligations not constituting Indebtedness) on any of its assets, now 
owned or hereafter acquired, securing any Indebtedness other than Senior 
Indebtedness, unless the Notes are secured equally and ratably with such 
other Indebtedness; PROVIDED that, if such Indebtedness is by its terms 
expressly subordinate to the Notes, the Lien securing such subordinate or 
junior Indebtedness shall be subordinate and junior to the Lien securing the 
Notes with the same relative priority as such subordinated or junior 
Indebtedness shall have with respect to the Notes.

     SECTION 4.14.  DIVIDENDS AND OTHER PAYMENT RESTRICTIONS AFFECTING 
SUBSIDIARIES.  The Company shall not, and shall not permit any of its 
Subsidiaries to, directly or indirectly, create or otherwise cause or suffer 
to exist or become effective any encumbrance or restriction on the ability of 
any Subsidiary to (i)(a) pay dividends or make any other distributions to the 
Company or any of its Subsidiaries on its Capital Stock or with respect to 
any other interest or participation in, or measured by, its profits, or (b) 
pay any indebtedness owed to the Company or any of its Subsidiaries, (ii) 
make loans or advances to the Company or any of its Subsidiaries, (iii) 
transfer any of its properties or assets to the Company or any of its 
Subsidiaries, (iv) transfer any of its property or assets to the Company or 
any of its Subsidiaries, (v) grant liens or security interests on the assets 
in favor of the Holders of Notes, or (vi) guarantee the Notes or any renewals 
or refinancings thereof, except for such encumbrances or restrictions 
existing under or by reason of (A) the Credit Facility, this Indenture and 
the Note, (B) applicable law, (C) any instrument governing Acquired 
Indebtedness or Capital Stock of a Person acquired by the Company or any of 
its Subsidiaries as in effect at the time of such acquisition (except to the 
extent such Acquired Indebtedness was incurred in connection with or in 
contemplation of such acquisition), which encumbrance or restriction is not 
applicable to any Person, or the properties or assets of any Person, other 
than the Person, or the property or assets of the Person, so acquired, 
PROVIDED that the Consolidated EBITDA of such Person is not taken into 
account in determining whether such acquisition was permitted by the terms of 
this Indenture, or (D) Permitted Refinancing Indebtedness, PROVIDED that the 
restrictions contained in the agreements governing such Permitted Refinancing 
Indebtedness are no more restrictive than those contained in the agreements 
governing the Indebtedness being refinanced.


                                     -46-

<PAGE>

     SECTION 4.15.  LIMITATION ON LAYERING DEBT.  The Company shall not 
incur, create, issue, assume, guarantee or otherwise become liable for any 
Indebtedness that is subordinate or junior in right of payment to any Senior 
Indebtedness and senior in any respect in right of payment of the Notes.

   
     SECTION 4.16.  TRANSACTIONS WITH AFFILIATES.  The Company shall not, and 
shall not permit any of its Subsidiaries to, after the date of this 
Indenture, sell, lease, transfer or otherwise dispose of any of its 
properties or assets to, or make any payment to, or purchase any property or 
assets from, or enter into or suffer to exist any transaction or series of 
transactions, or make any agreement, loan, advance or guarantee with, or for 
the benefit of, any Affiliate (each of the foregoing, an "Affiliate 
Transaction"), other than Exempt Affiliate Transactions, unless (i) such 
Affiliate Transaction is on terms that are no less favorable to the Company 
or the relevant Subsidiary (as reasonably determined by the Company) than 
those that would have been obtained in a comparable transaction by the 
Company or such Subsidiary with an unrelated Person and (ii) the Company 
delivers to the Trustee (a) with respect to any Affiliate Transaction entered 
into after the date of this Indenture involving aggregate consideration in 
excess of $1.0 million, a resolution of the Board of Directors set forth in an 
Officers' Certificate certifying that such Affiliate Transaction complies 
with clause (i) above and that such Affiliate Transaction has been approved 
by a majority of the disinterested members of the Board of Directors and (b) 
with respect to any Affiliate Transaction involving aggregate consideration 
in excess of $5.0 million, an opinion as to the fairness to the Company or 
such Subsidiary of such Affiliate Transaction from a financial point of view 
issued by an investment banking firm of national standing.
    

     SECTION 4.17.  REPORTS.  Whether or not required by the rules and 
regulations of the Commission, so long as any Notes are outstanding, the 
Company shall furnish to the Holders of Notes, and file with the Trustee, 
within 15 days after it is, or would have been, required to file such with 
the Commission (i) all quarterly and annual financial information that is or 
would be required to be contained in a filing with the Commission on Forms 
10-Q and 10-K if the Company is or were required to file such Forms, 
including a "Management's Discussion and Analysis of Financial Condition and 
Results of Operations" and, with respect to the annual information only, a 
report thereon by the Company's certified independent accountants and (ii) 
all current reports that are or would be required to be filed with the 
Commission on Form 8-K if the Company is or were required to file such 
reports.  In addition, whether or not required by the rules and regulations 
of the Commission, the Company shall file a copy of all such information and 
reports with the Commission for public availability (unless the Commission 
will not accept such a filing) and make such information available to 
securities analysts and prospective investors upon written request.

     Delivery of such reports, information and documents to the Trustee is 
for informational purposes only and the Trustee's receipt of such shall not 
constitute constructive notice of any information contained therein or 
determinable from information contained therein, including the Company's 
compliance with any of its covenants hereunder (as to which the Trustee is 
entitled to rely exclusively on Officers' Certificates).


                                     -47-

<PAGE>

     SECTION 4.18.  WAIVER OF STAY, EXTENSION OR USURY LAWS.  Each of the 
Company and the Subsidiary Guarantors covenants (to the extent that it may 
lawfully do so) that it will not at any time insist upon, or plead, or in any 
manner whatsoever claim or take the benefit or advantage of, any stay or 
extension law or any usury law or other law that would prohibit or forgive 
the Company or such Subsidiary Guarantor from paying all or any portion of 
the principal of or premium, if any, or interest on the Notes as contemplated 
herein, wherever enacted, now or at any time hereafter in force, or that may 
affect the covenants or the performance of this Indenture; and (to the extent 
that it may lawfully do so) the Company or such Subsidiary Guarantor hereby 
expressly waives all benefit or advantage of any such law and covenants that 
it will not hinder, delay or impede the execution of any power herein granted 
to the Trustee, but will suffer and permit the execution of every such power 
as though no such law had been enacted.

     SECTION 4.19.  COMPLIANCE CERTIFICATE; NOTICE OF DEFAULT OR EVENT OF 
DEFAULT. (a)  The Company shall deliver to the Trustee within 120 calendar 
days after the end of each fiscal year of the Company ending after the date 
hereof, an Officers' Certificate stating whether or not, to the best 
knowledge of such officer, the Company has complied with all conditions and 
covenants under this Indenture, and, if the Company shall be in Default, 
specifying all such Defaults and the nature thereof of which such officer may 
have knowledge.

     For the purposes of this Section 4.19(a), compliance shall be determined 
without regard to any period of grace or requirement of notice under this 
Indenture.

     (b)  The Company shall deliver written notice to the Trustee immediately 
upon any executive officer of the Company becoming aware of the occurrence of 
any event which constitutes, or with the giving of notice or the lapse of 
time or both would constitute, a Default or Event of Default, describing such 
Default or Event of Default, its status and what action the Company is taking 
or proposes to take with respect thereto.

     (c)  So long as not contrary to the then-current recommendations of the 
American Instituted of Certified Public Accountants, the year-end financial 
statements delivered pursuant to Section 4.17 hereof shall be accompanied by 
a written statement of the Company's independent public accountants (who 
shall be a firm of established national reputation) that in making the 
examination necessary for certification of such financial statements, nothing 
has come to their attention that would lead them to believe that the Company 
has violated any provisions of Article IV or Article V hereof or, if any such 
violation has occurred, specifying the nature and period of existence 
thereof, it being understood that such accountants shall not be liable 
directly or indirectly to any Person for any failure to obtain knowledge of 
any such violation.

     SECTION 4.20.  INVESTMENT COMPANY ACT.  None of the Company or the 
Subsidiaries or Unrestricted Subsidiaries of the Company shall become an 
investment company subject to registration under the Investment Company Act 
of 1940, as amended.


                                     -48-

<PAGE>

     SECTION 4.21.  SALE AND LEASEBACK.  The Company will not, and will not 
permit any of its Subsidiaries to, enter into any Sale and Leaseback 
Transaction unless (a) the Company or its Subsidiaries entering into such 
Sale and Leaseback Transaction could have incurred the Indebtedness relating 
to such Sale and Leaseback Transaction pursuant to Sections 4.12 and 4.13 and 
(b) the Net Proceeds of such Sale and Leaseback Transaction are at least 
equal to the fair market value of such property as determined by the Board of 
Directors of the Company.

     SECTION 4.22.  FURTHER INSTRUMENTS AND ACTS.  Upon request of the 
Trustee, the Company shall execute and deliver such further instruments and 
do such further acts as may be reasonably necessary or proper to carry out 
more effectively the purpose of this Indenture.

                                  ARTICLE V

                            CONSOLIDATION, MERGER,
                         CONVEYANCE, LEASE OR TRANSFER
   
     SECTION 5.01.  MERGER, CONSOLIDATION OR SALE OF ASSETS.  The Company 
shall not, and shall not permit any Subsidiary to, in a single transaction or 
series of related transactions consolidate or merge with or into (other than 
the consolidation or merger of a Wholly Owned Subsidiary of the Company with 
another Wholly Owned Subsidiary of the Company or into the Company) (whether 
or not the Company or such Subsidiary is the surviving corporation), or 
directly and/or indirectly through its Subsidiaries sell, assign, transfer, 
lease, convey or otherwise dispose of all or substantially all of its 
properties or assets (determined on a consolidated basis for the Company and 
its Subsidiaries taken as a whole) in one or more related transactions to, 
another corporation, Person or entity unless (i) either (a) the Company, in 
the case of a transaction involving the Company, or such Subsidiary, in the 
case of a transaction involving a Subsidiary, is the surviving corporation or 
(b) in the case of a transaction involving the Company, the entity or the 
Person formed by or surviving any such consolidation or merger (if other than 
the Company) or to which such sale, assignment, transfer, lease, conveyance 
or other disposition shall have been made is a corporation organized or 
existing under the laws of the United States, any state thereof or the 
District of Columbia and assumes all the obligations of the Company under the 
Notes and this Indenture pursuant to a supplemental indenture in a form 
reasonably satisfactory to the Trustee; (ii) immediately after such 
transaction no Default or Event of Default exists; and (iii) the Company or, 
if other than the Company, the entity or Person formed by or surviving any 
such consolidation or merger, or to which such sale, assignment, transfer, 
lease, conveyance or other disposition shall have been made (A) will have 
Consolidated Net Worth immediately after the transaction equal to or greater 
than the Consolidated Net Worth of the Company immediately preceding the 
transaction and (B) will, at the time of such transaction and after giving 
pro forma effect thereto as if such transaction had occurred at the beginning 
of the applicable four-quarter period, be permitted to incur at least $1.00 
of additional Indebtedness pursuant to the Consolidated Interest Coverage 
Ratio and the Adjusted Consolidated Net Tangible Assets to Consolidated 
Indebtedness Ratio tests set forth in Section 4.12(a) hereof.
    

                                     -49-


<PAGE>

     In connection with any consolidation, merger, conveyance, lease or other 
disposition contemplated by this Section 5.01, the Company shall deliver, or 
cause to be delivered, to the Trustee, in form reasonably satisfactory to the 
Trustee, an Officers' Certificate of the Company and an Opinion of Counsel of 
the Company, each stating that such consolidation, merger, conveyance, lease 
or disposition and any supplemental indenture in respect thereto comply with 
this Section 5.01 and that all conditions precedent herein provided for 
relating to such transaction have been complied with.

   
     SECTION 5.02.  SUCCESSOR CORPORATION SUBSTITUTED.  Upon any consolidation 
with, or merger by the Company with and into, any other corporation, or any 
sale, assignment, transfer, lease, conveyance or other disposition of all or 
substantially all of the Property of the Company and its Subsidiaries taken 
as a whole in accordance with Section 5.01 hereof, the successor corporation 
formed by such consolidation or into which the Company is merged, or the 
Person to which such sale, conveyance, assignment, transfer, lease, 
conveyance or other disposition is made, shall succeed to, and be substituted 
for, and may exercise every right and power of, the Company under this 
Indenture with the same effect as if such successor Person has been named as 
the Company herein; and thereafter the predecessor corporation shall be 
relieved of all obligations and covenants under this Indenture and the Notes, 
EXCEPT for the obligation to pay the principal of (and premium, if any) and 
interest on the Notes.
    

                                  ARTICLE VI

                             DEFAULTS AND REMEDIES
   
     SECTION 6.01.  EVENTS OF DEFAULT.  "Event of Default," wherever used 
herein with respect to the Notes, means any one of the following events 
(whatever the reason for such event, and whether it shall be voluntary or 
involuntary, or be effected by operation of law, pursuant to any judgment, 
decree or order of any court or any order, rule or regulation of any 
administrative or governmental body):
    
          (a)  The Company or any Subsidiary Guarantor fails to make any 
     payment of interest on any Note when the same becomes due and payable 
     and such failure continues for a period of 30 calendar days, whether or 
     not such payment is prohibited by the provisions of Articles X or XI 
     hereof; or

          (b)  The Company or any Subsidiary Guarantor fails to make any 
     payment of the principal or of premium, if any, on any Note when the 
     same becomes due and payable whether upon maturity, redemption, required 
     repurchase or otherwise, whether or not such payment is prohibited by 
     the provisions of Articles X or XI hereof; or

          (c)  the Company or any Subsidiary fails to observe or perform any 
     covenant, condition or agreement on the part of the Company to be 
     observed or performed pursuant to Section 4.07, 4.08, 4.09, 4.11 or 4.12 
     hereof or Article V hereof; or


                                     -50-

<PAGE>

          (d)  the Company or any Subsidiary fails to comply with any of its 
     other agreements or covenants in, or provisions of, the Notes or this 
     Indenture and such failure continues for the period and after the notice 
     specified below; or

          (e)  a default occurs under any mortgage, indenture or instrument 
     under which there may be issued or by which there may be secured or 
     evidenced any Indebtedness for money borrowed by the Company or any of 
     its Subsidiaries (or the payment of which is Guaranteed by the Company 
     or any of its Subsidiaries), whether such Indebtedness or Guarantee now 
     exists or shall be created after the date of this Indenture, which 
     default (i) is caused by a failure to pay principal of such Indebtedness 
     at final maturity thereof (a "Payment Default) or (ii) results in the 
     acceleration of such Indebtedness prior to its express maturity and, in 
     each case, the principal amount of such Indebtedness, together with the 
     principal amount of any other Indebtedness as to which there has been a 
     Payment Default or the maturity of which has been so accelerated, 
     aggregates $10.0 million or more; or

          (f)  a final judgment or final judgments for the payment of money 
     not fully covered by insurance are entered by a court or courts of 
     competent jurisdiction against the Company or any of its Subsidiaries 
     and such judgment or judgments remain undischarged for a period (during 
     which execution shall not be effectively stayed) of 60 days, PROVIDED 
     that the aggregate of all such undischarged judgments exceeds $1.0 
     million; or

          (g)  the entry by a court having jurisdiction in the premises of 
     (i) a decree or order for relief in respect of the Company or any 
     Subsidiary of the Company in an involuntary case or proceeding under 
     United States bankruptcy laws, as now or hereafter constituted, or any 
     other applicable Federal, state, or foreign bankruptcy, insolvency, or 
     other similar law or (ii) a decree or order adjudging the Company or any 
     Subsidiary of the Company a bankrupt or insolvent, or approving as 
     properly filed a petition seeking reorganization, arrangement, 
     adjustment or composition of, or in respect of, the Company or any 
     Subsidiary of the Company under United States bankruptcy laws, as now or 
     hereafter constituted, or any other applicable Federal, state or foreign 
     bankruptcy, insolvency, or similar law, or appointing a custodian, 
     receiver, liquidator, assignee, trustee, sequestrator or other similar 
     official of the Company or any Subsidiary of the Company or of any 
     substantial part of the Property of the Company or any Subsidiary of the 
     Company, or ordering the winding-up or liquidation of the affairs of the 
     Company or any Subsidiary of the Company, and the continuance of  any 
     such decree or order for relief or any such other decree or order 
     unstayed and in effect for a period of 60 consecutive calendar days; or

          (h)  (i) the commencement by the Company or any Subsidiary of the 
     Company of a voluntary case or proceeding under United States bankruptcy 
     laws, as now or hereafter constituted, or any other applicable Federal, 
     state, or foreign bankruptcy, insolvency or other similar law or of any 
     other case or proceeding to be adjudicated a bankrupt or insolvent; or 
     (ii) the consent by the Company or any Subsidiary of the Company to the 
     entry of a decree or order for relief in respect of the Company or any 
     Subsidiary or Unrestricted Subsidiary of the Company 


                                     -51-

<PAGE>


     in an involuntary case or proceeding under United States bankruptcy 
     laws, as now or hereafter constituted, or any other applicable Federal, 
     state, or foreign bankruptcy, insolvency, or other similar law or to the 
     commencement of any bankruptcy or insolvency case or proceeding against 
     the Company or any Subsidiary of the Company; or (iii) the filing by the 
     Company or any Subsidiary of the Company of a petition or answer or 
     consent seeking reorganization or relief under United States bankruptcy 
     laws, as now or hereafter constituted, or any other applicable Federal, 
     state or foreign bankruptcy, insolvency or other similar law; or (iv) 
     the consent by the Company or any Subsidiary of the Company to the 
     filing of such petition or to the appointment of or taking possession by 
     a custodian, receiver, liquidator, assignee, trustee, sequestrator or 
     similar official of the Company or any Subsidiary of the Company or of 
     any substantial part of the Property of the Company or any Subsidiary of 
     the Company, or the making by the Company or any Subsidiary of the 
     Company of an assignment for the benefit of creditors; or (v) the 
     admission by the Company or any Subsidiary of the Company in writing of 
     its inability to pay its debts generally as they become due; or (vi) the 
     taking of corporate action by the Company or any Subsidiary of the 
     Company in furtherance of any such action; or

   
          (i)  any Subsidiary Guarantee or any provision thereof shall at any 
     time cease to be the legal, valid and binding obligation of the 
     Subsidiary Guarantor party thereto as represented in the Subsidiary 
     Guarantee (other than pursuant to Section 11.02 hereof or Section 2 of the
     Subsidiary Guarantees), such that the Holders of the Notes could not
     reasonably be expected to realize the material benefits intended to be
     provided by such Subsidiary Guarantor under the Subsidiary Guarantee or
     any Subsidiary Guarantor shall assert that the Subsidiary Guarantee is not
     a legal, valid and binding obligation or shall purport to revoke its 
     obligations thereunder.
    

     A Default under clause (d) is not an Event of Default until the Trustee 
notifies the Company, or the Holders of at least 25% in principal amount of 
the then outstanding Notes notify the Company and the Trustee, of the Default 
and the Company does not cure the Default within 60 calendar days after 
receipt of the notice. The notice must specify the Default, demand that it be 
remedied and state that the notice is a "Notice of Default".

   
     SECTION 6.02.  ACCELERATION.  If an Event of Default (other than an Event 
of Default specified in Section 6.01(g) or Section 6.01(h)) occurs and is 
continuing, then and in every such case the Trustee by notice to the Company, 
or the Holders of at least 25% in principal amount of the then outstanding 
Notes by written notice to the Company and the Trustee may declare the unpaid 
principal of and any accrued interest on all the Notes then outstanding to be 
immediately due and payable.  Upon such declaration the principal and 
interest shall be due and payable immediately (together with any premium, if 
applicable).  If an Event of Default specified in Section 6.01(g) or Section 
6.01(h) occurs, such an amount shall IPSO FACTO become and be immediately due 
and payable without any declaration or other act on the part of the Trustee 
or any Holder.
    

     The Holders of a majority in principal amount of the then outstanding 
Notes by written notice to the Trustee may rescind an acceleration and its 
consequences if the rescission would not conflict with any judgment or decree 
and if all existing Events of Default (except nonpayment of principal, 
interest or premium that have become due solely because of the acceleration) 
have been cured or 


                                     -52-

<PAGE>

waived.  No such recession shall affect any subsequent Default or impair any 
right consequent thereon.

   
     SECTION 6.03.  OTHER REMEDIES.  The Company covenants that if an Event of 
Default specified in Section 6.01(a) or Section 6.01(b) occurs the Company 
shall, upon demand of the Trustee, pay to the Trustee, for the benefit of the 
Holders, the whole amount then due and payable  on the Notes for principal 
(and premium, if any) and interest and, to the extent that payment of such 
interest shall be legally enforceable, interest upon the overdue principal 
(and premium, if any) and upon Defaulted Interest at the rate or rates 
prescribed therefor in such Notes; and, in addition thereto, such further 
amount as shall be sufficient to cover the costs and expenses of collection, 
including the reasonable compensation, expenses, disbursements and advances 
of the Trustee, its agents and counsel and all other amounts due to the 
Trustee pursuant to Section 7.07 hereof.
    

     If the Company fails to pay such amounts forthwith upon such demand, the 
Trustee, in its own name and as trustee of an express trust, may institute a 
judicial proceeding for the collection of the sums so due and unpaid, and may 
prosecute such proceeding to judgment or final decree, and may enforce the 
same against the Company or any other obligor upon such Notes and collect the 
moneys adjudged or decreed to be payable in the manner provided by law out of 
the Property of the Company or any other obligor upon such Notes, wherever 
situated.

     If an Event of Default with respect to the Notes occurs and is 
continuing, the Trustee may in its discretion proceed to protect and enforce 
its rights and the rights of the Holders by such appropriate judicial 
proceedings as the Trustee shall deem most effectual to protect and enforce 
any such rights, whether for the specific enforcement of any covenant or 
agreement in this Indenture or in aid of the exercise of any power granted 
herein, or to enforce any other proper remedy.

   
     SECTION 6.04.  WAIVER OF PAST DEFAULTS.  The Holders of not less than a 
majority in principal amount of the outstanding Notes may, on behalf of the 
Holders of all the Notes, waive any past Default and its consequences under 
this Article VI, except Default (a) in the payment of the principal of (or 
premium, if any) or interest on, any Note (except a payment default resulting 
from an acceleration that has been rescinded), or (b) in respect of a 
covenant or provision hereof which under Section 9.02 hereof cannot be 
modified or amended without the consent of the Holder of each outstanding 
Note affected.  Any such waiver may (but need not) be given in connection 
with a tender offer or exchange offer for the Notes.

     SECTION 6.05.  CONTROL BY MAJORITY.  The Holders of not less than a 
majority in principal amount of the outstanding Notes shall have the right to 
direct the time, method and place of conducting any proceeding for any remedy 
available to the Trustee or exercising any trust or power conferred on the 
Trustee; PROVIDED that:
    

                                     -53-

<PAGE>

          (a)  such direction shall not be in conflict with any rule of law 
     or with this Indenture or unduly prejudicial to the rights of other 
     Holders and would not subject the Trustee to personal liability, and

          (b)  the Trustee may take any other action deemed proper by the 
     Trustee which is not inconsistent with such direction.

   
     SECTION 6.06.  LIMITATION ON SUITS.  No Holder of Notes shall have any 
right to institute any proceeding, judicial or otherwise, with respect to 
this Indenture, or for the appointment of a receiver or trustee, or for any 
other remedy hereunder, unless
    

          (a)  such Holder has previously given written notice to the Trustee 
     of a continuing Event of Default with respect to the Notes;

          (b)  the Holders of not less than 25 percent in principal amount of 
     the outstanding Notes shall have made written request to the Trustee to 
     institute proceedings in respect of such Event of Default in its own 
     name as Trustee hereunder;

          (c)  such Holder or Holders have offered to the Trustee security or 
     indemnity satisfactory to the Trustee in its reasonable discretion 
     against the costs, expenses and liabilities to be incurred in compliance 
     with such request;

          (d)  the Trustee for 30 calendar days after its receipt of such 
     notice, request and offer of indemnity has failed to institute any such 
     proceeding; and 

          (e)  no direction inconsistent with such written request has been 
     given to the Trustee during such 30-day period by the Holders of a 
     majority in principal amount of the outstanding Notes;

in any event, it being understood and intended that no one or more Holders of 
Notes shall have any right in any manner whatever by virtue of, or by 
availing of, any provision of this Indenture to affect, disturb or prejudice 
the rights of any other Holders of Notes, or to obtain or to seek to obtain 
priority or preference over any other of such Holders or to enforce any right 
under this Indenture, except in the manner herein provided and for the equal 
and ratable benefit of all Holders of Notes.

   
     SECTION 6.07.  RIGHTS OF HOLDERS TO RECEIVE PAYMENT.  Notwithstanding any 
other provision of this Indenture, the right of any Holder to receive payment 
of principal of (premium, if any) and interest on the Notes held by such 
Holder, on or after the respective due dates expressed in the Notes or the 
redemption dates or purchase dates provided for therein, or to bring suit for 
the enforcement of any such payment on or after such respective dates, shall 
be absolute and unconditional and shall not be impaired or affected without 
the consent of such Holder.
    

                                     -54-

<PAGE>

   
     SECTION 6.08.  TRUSTEE MAY FILE PROOFS OF CLAIM.  In case of the pendency 
of any receivership, insolvency, liquidation, bankruptcy, reorganization, 
arrangement, adjustment, composition or other judicial proceedings, or any 
voluntary or involuntary case under United States bankruptcy laws, as now or 
hereafter constituted, relative to the Company, any Subsidiary Guarantor or 
any other obligor upon the Notes or the Property of the Company, any 
Subsidiary Guarantor or of such other obligor or their creditors, the Trustee 
(irrespective of whether the principal of such Notes shall then be due and 
payable as therein expressed or by declaration or otherwise and irrespective 
of whether the Trustee shall have made any demand on the Company or any 
Subsidiary Guarantor for the payment of overdue principal or interest) shall 
be entitled and empowered, by intervention in such proceeding or otherwise, 
(i) to file and prove a claim for the whole amount of principal (and premium, 
if any) and interest owing and unpaid in respect of the Notes, to file such 
other papers or documents and to take such other actions, including 
participating as a member or otherwise in any official committee of creditors 
appointed in the matter, as may be necessary or advisable in order to have 
the claims of the Trustee (including any claim for the reasonable 
compensation, expenses, disbursements and advances of the Trustee, its agents 
and counsel and all other amounts due to the Trustee pursuant to Section 7.07 
hereof) and of the Holders allowed in such judicial proceeding, and (ii) to 
collect and receive any moneys or other Property payable or deliverable on 
any such claims and to distribute the same; and any receiver, assignee, 
trustee, custodian, liquidator, sequestrator (or other similar official) in 
any such proceeding is hereby authorized by each Holder to make such payments 
to the Trustee, and in the event that the Trustee shall consent to the making 
of such payments directly to the Holders, to pay to the Trustee any amount 
due it for the reasonable compensation, expenses, disbursements and advances 
of the Trustee, its agents and counsel, and any other amounts due the Trustee 
under Section 7.07 hereof.  Nothing contained herein shall be deemed to 
authorize the Trustee to authorize or consent to or accept or adopt on behalf 
of any Holder any plan of reorganization, arrangement, adjustment or 
composition affecting the Notes or the rights of any Holder thereof, or to 
authorize the Trustee to vote in respect of the claim of any Holder in any 
such proceeding.

     SECTION 6.09.  PRIORITIES.  Any money collected by the Trustee pursuant 
to this Article VI shall be applied in the following order, at the date or 
dates fixed by the Trustee and, in case of the distribution of such money on 
account of principal (premium, if any) or interest upon presentation of the 
Notes and the notation thereon of the payment if only partially paid and upon 
surrender thereof if fully paid:
    

          (a)  FIRST: To the payment of all amounts due the Trustee under 
     Section 7.07 hereof;

          (b)  SECOND: To the payment of the amounts then due and unpaid for 
     principal of (and premium, if any) and interest on the Notes, ratably, 
     without preference or priority of any kind, according to the amounts due 
     and payable on such Notes for principal (and premium, if any) and 
     interest, respectively; and

          (c)  THIRD: To the Company.


                                     -55-

<PAGE>

     The Trustee may fix a record date and payment date for any payment to 
Holders pursuant to this Section 6.09. At least 15 calendar days before such 
record date, the Company shall mail to each Holder and the Trustee a notice 
that states such record date, the payment date and amount to be paid.  The 
Trustee may mail such notice in the name and at the expense of the Company.

     SECTION 6.10.  UNDERTAKING FOR COSTS.  All parties to this Indenture 
agree, and each Holder of any Note by such Holder's acceptance thereof shall 
be deemed to have agreed, that any court may in its discretion require, in 
any suit for the enforcement of any right or remedy under this Indenture, or 
in any suit against the Trustee for any action taken, suffered or omitted by 
it as Trustee, the filing by any party litigant in such suit of an 
undertaking to pay the costs of such suit and that such court may in its 
discretion assess reasonable costs, including reasonable attorneys' fees and 
expenses, against any party litigant in such suit, having due regard to the 
merits and good faith of the claims or defenses made by such party litigant; 
but the provisions of this Section shall not apply to any suit instituted by 
the Trustee, to any suit instituted by any Holder, or group of Holders, 
holding in the aggregate more than 10 percent in principal amount of the 
outstanding Notes, or to any suit instituted by any Holder for the 
enforcement of the payment of the principal of (or premium, if any) or 
interest on any Note on or after its Stated Maturity.

     SECTION 6.11.  WAIVER OF STAY OR EXTENSION LAWS.  The Company and the 
Subsidiary Guarantors (to the extent it or they may lawfully do so) shall not 
at any time insist upon, or plead, or in any manner whatsoever claim or take 
the benefit or advantage of, any stay or extension law wherever enacted, now 
or at any time hereafter in force, which may affect the covenants or the 
performance of this Indenture; and the Company and the Subsidiary Guarantors 
(to the extent that it or they may lawfully do so) hereby expressly waives 
all benefit or advantage of any such law, and shall not hinder, delay or 
impede the execution of any power herein granted to the Trustee, but shall 
suffer and permit the execution of every such power as though no such law had 
been enacted.

     SECTION 6.12.  TRUSTEE MAY ENFORCE CLAIMS WITHOUT POSSESSION OF THE 
NOTES.  All rights of action and claims under this Indenture or the Notes may 
be prosecuted and enforced by the Trustee without the possession of any of 
the Notes or the production thereof in any proceeding relating thereto, and 
any such proceeding instituted by the Trustee shall be brought in its own 
name, as trustee of an express trust, and any recovery of judgment shall, 
after provision for the payment of the reasonable compensation, expenses, 
disbursements and advances of the Trustee, its agents and counsel, be for the 
ratable benefit of the Holders of the Notes.

     SECTION 6.13.  RESTORATION OF RIGHTS AND REMEDIES.  If the Trustee or 
any Holder of Notes has instituted any proceeding to enforce any right or 
remedy under this Indenture and such proceeding has been discontinued or 
abandoned for any reason, or has been determined adversely to the Trustee or 
to such Holder, then and in every such case the Company, the Subsidiary 
Guarantors, the Trustee and the Holders shall, subject to any determination 
in such proceeding, be restored severally and respectively to their former 
positions hereunder, and thereafter all rights and remedies of the Trustee 
and the Holders shall continue as though no such proceeding had been 
instituted.


                                     -56-

<PAGE>

     SECTION 6.14.  RIGHTS AND REMEDIES CUMULATIVE.  Except as otherwise 
provided in Section 2.07 hereof, no right or remedy herein conferred upon or 
reserved to the Trustee or to the Holders is intended to be exclusive of any 
other right or remedy, and every right and remedy shall, to the extent 
permitted by law, be cumulative and in addition to every other right and 
remedy given hereunder or now or hereafter existing at law or in equity or 
otherwise.  The assertion or employment of any right or remedy hereunder, or 
otherwise, shall not prevent the concurrent assertion or employment of any 
other appropriate right or remedy.

     SECTION 6.15.  DELAY OR OMISSION NOT WAIVER.  No delay or omission of 
the Trustee or of any Holder of any Note to exercise any right or remedy 
accruing upon any Event of Default shall impair any such right or remedy or 
constitute a waiver of any such Event of Default or an acquiescence therein.  
Every right and remedy given by this Article VI or by law to the Trustee or 
to the Holders may be exercised from time to time, and as often as may be 
deemed expedient, by the Trustee or by the Holders, as the case may be.

                                 ARTICLE VII

                                   TRUSTEE

   
     SECTION 7.01.  DUTIES OF TRUSTEE. (a)  If an Event of Default has 
occurred and is continuing, the Trustee shall exercise the rights and powers 
vested in it by this Indenture and shall use the same degree of care and 
skill in their exercise as a prudent person would exercise or use under the 
circumstances in the conduct of such person's own affairs.
    

     (b)  Except during the continuance of an Event of Default:  (i) the 
Trustee undertakes to perform such duties and only such duties as are 
specifically set forth in this Indenture and no implied covenants or 
obligations shall be read into this Indenture against the Trustee; and (ii) 
in the absence of bad faith on its part, the Trustee may conclusively rely, 
as to the truth of the statements and the correctness of the opinions 
expressed therein, upon certificates or opinions furnished to the Trustee and 
conforming to the requirements of this Indenture; PROVIDED that in the case 
of any such certificates or opinions that by any provision of this Indenture 
are specifically required to be furnished to the Trustee, the Trustee shall 
examine such certificates and opinions to determine whether or not they 
conform to the requirements of this Indenture.

     (c)  The Trustee may not be relieved from liability for its own 
negligent action, its own negligent failure to act or its own willful 
misconduct, PROVIDED that: (i) this paragraph (c) shall not limit the effect 
of paragraph (b) of this Section 7.01; (ii) the Trustee shall not be liable 
for any error of judgment made in good faith by a Trust Officer unless it is 
proved that the Trustee was negligent in ascertaining the pertinent facts; 
and (iii) the Trustee shall not be liable with respect to any action it takes 
or omits to take in good faith in accordance with a direction received by it 
pursuant to Section 6.05 hereof.


                                     -57-

<PAGE>

     (d)  The Trustee shall not be liable for interest on any money received 
by it except as the Trustee may agree in writing with the Company.

     (e)  Money held in trust by the Trustee need not be segregated from 
other funds except to the extent required by law.

     (f)  No provision of this Indenture shall require the Trustee to expend 
or risk its own funds or otherwise incur any financial liability in the 
performance of any of its duties hereunder, or in the exercise of any of its 
rights or powers, if it shall have reasonable grounds for believing that 
repayment of such funds or adequate indemnity against such risk of liability 
is not reasonably assured to it.

     (g)  Every provision of this Indenture relating to the conduct or 
affecting the liability of or affording protection to the Trustee shall be 
subject to the provisions of this Article VII and to the provisions of the 
Trust Indenture Act.

   
     SECTION 7.02.  RIGHTS OF TRUSTEE. (a) The Trustee may rely on any 
document believed by it to be genuine and to have been signed or presented by 
the proper Person.  Except as provided in Section 7.01(b) hereof, the Trustee 
need not investigate any fact or matter stated in the document.
    

     (b)  Before the Trustee acts or refrains from acting, it may require an 
Officers' Certificate or an Opinion of Counsel.  The Trustee shall not be 
liable for any action it takes or omits to take in good faith in reliance on 
any Officers' Certificate or Opinion of Counsel.

     (c)  The Trustee may act through agents and shall not be responsible for 
the misconduct or negligence of any such agent; PROVIDED that such agent was 
appointed with due care by the Trustee.

     (d)  The Trustee shall not be liable for any action it takes or omits to 
take in good faith which it believes to be authorized or within its rights or 
powers; PROVIDED that the Trustee's conduct does not constitute willful 
misconduct or gross negligence.

     (e)  The Trustee shall not be charged with knowledge of any Default or 
Event of Default under Sections 6.01(c), 6.01(d), 6.01(e) or 6.01(f) hereof, 
of the identity of any Subsidiary or of the existence of any Change of 
Control or Asset Sale unless either (i) a Trust Officer shall have actual 
knowledge thereof, or (ii) the Trustee shall have received notice thereof in 
accordance with Section 12.02 hereof from the Company or any Holder of Notes.

     (f)  The Trustee may consult with counsel of its selection and the 
advice of such counsel or any Opinion of Counsel shall be full and complete 
authorization and protection in respect of any action taken, suffered or 
omitted by it hereunder in good faith and in reliance thereon.

     (g)  The Trustee shall not be bound to make any investigation into the 
facts or matters stated in any resolution, certificate, statement, 
instrument, opinion, report, notice, request, direction, 


                                     -58-

<PAGE>

consent, order, bond, debenture or other paper or document, but the Trustee, 
in its discretion may make such further inquiry or investigation into such 
facts or matters as it may see fit, and, if the Trustee shall determine to 
make such further inquiry or investigation, it shall be entitled to examine 
the books, records and premises of the Company, personally or by agent or 
attorney.

   
     SECTION 7.03.  INDIVIDUAL RIGHTS OF TRUSTEE.  The Trustee, any Paying 
Agent or Registrar, in its individual or any other capacity, may become the 
owner or pledgee of Notes and may otherwise deal with the Company or its 
Affiliates with the same rights it would have if it were not Trustee, Paying 
Agent or Registrar hereunder, as the case may be; PROVIDED that the Trustee 
must in any event comply with Section 7.10 and Section 7.11 hereof.

     SECTION 7.04.  TRUSTEE'S DISCLAIMER.  The Trustee shall not be 
responsible for and makes no representation as to the validity or adequacy of 
this Indenture or the Notes, it shall not be accountable for the Company's 
use of the proceeds from the Notes, and it shall not be responsible for any 
statement of the Company in this Indenture, including the recitals contained 
herein, or in any document issued in connection with the sale of the Notes or 
in the Notes other than the Trustee's certificate of authentication.

     SECTION 7.05.  NOTICE OF DEFAULTS.  Within 90 calendar days after the 
occurrence of any Default hereunder with respect to the Notes, the Trustee 
shall transmit by mail to all Holders, as their names and addresses appear in 
the Security Register, notice of such Default hereunder known to the Trustee, 
unless such Default shall have been cured or waived, PROVIDED that, except in 
the case of a Default in the payment of the principal of (or premium, if any) 
or interest on any Note, the Trustee shall be protected in withholding such 
notice if and so long as the board of directors, the executive committee or a 
trust committee of directors and/or Trust Officers of the Trustee in good 
faith determine that the withholding of such notice is in the interest of the 
Holders.

     SECTION 7.06.  PRESERVATION OF INFORMATION; REPORTS BY TRUSTEE TO 
HOLDERS. (a) The Company shall furnish or cause to be furnished to the 
Trustee:
    

          (i)  semiannually, not less than 10 calendar days prior to each 
     Interest Payment Date, a list, in such form as the Trustee may 
     reasonably require, of the names and addresses of the Holders as of the 
     Record Date immediately preceding such Interest Payment Date, and

          (ii)  at such other times as the Trustee may request in writing, 
     within 30 calendar days after the receipt by the Company of any such 
     request, a list of similar form and content as of a date not more than 
     15 calendar days prior to the time such list is furnished;

PROVIDED, HOWEVER, that if and so long as the Trustee shall be the Registrar 
for the Notes, no such list need be furnished with respect to the Notes.

     (b)  The Trustee shall preserve, in as current a form as is reasonably 
practicable, the names and addresses of Holders contained in the most recent 
list furnished to the Trustee as provided in 


                                     -59-

<PAGE>

Section 7.06(a) hereof and the names and addresses of Holders received by the 
Trustee in its capacity as Registrar, if so acting.  The Trustee may destroy 
any list furnished to it as provided in Section 7.06(a) hereof upon receipt 
of a new list so furnished.

     (c)  Holders may communicate as provided in Section 312(b) of the Trust 
Indenture Act with other Holders with respect to their rights under this 
Indenture or under the Notes.

     (d)  Each Holder of Notes, by receiving and holding the same, agrees 
with the Company and the Trustee that neither the Company nor the Trustee 
shall be held accountable by reason of the disclosure of any such information 
as to the names and addresses of the Holders in accordance with this Section 
7.06, regardless of the source from which such information was derived, and 
that the Trustee shall not be held accountable by reason of mailing any 
material pursuant to a request made under this Section 7.06.

     (e)  Within 60 calendar days after May 15 of each year commencing 
with the year 1997, the Trustee shall transmit by mail to all Holders of 
Notes, a brief report dated as of such May 15 if and to the extent 
required under Section 313(a) of the Trust Indenture Act.

     (f)  The Trustee shall comply with Sections 313(b) and 313(c) of the 
Trust Indenture Act.

     (g)  A copy of each report described in Section 7.06(e) hereof shall, at 
the time of its transmission to Holders, be filed by the Trustee with each 
stock exchange, if any, upon which the Notes are then listed, with the 
Commission and also with the Company.  The Company shall promptly notify the 
Trustee of any stock exchange upon which the Notes are listed.

   
     SECTION 7.07.  COMPENSATION AND INDEMNITY.  The Company shall pay to the 
Trustee from time to time such compensation for its services as the Company 
and the Trustee shall from time to time agree.  The Company shall reimburse 
the Trustee upon request for all reasonable out-of-pocket expenses incurred 
or made by it, including costs of collection, in addition to the compensation 
for its services.  Such expenses shall include the reasonable compensation 
and expenses, disbursements and advances of the Trustee's agents and counsel. 
The Trustee's compensation shall not be limited by any law on compensation 
of a trustee of an express trust.
    

     The Company shall indemnify the Trustee for, and hold it harmless 
against, any and all loss, liability, damage, claim or expense (including 
reasonable attorneys' fees and expenses) arising out of or incurred by it in 
connection with the acceptance or administration of the trust created by this 
Indenture and the performance of its duties hereunder, except as set forth in 
the next paragraph.  The Trustee shall notify the Company promptly of any 
claim for which it may seek indemnity.  Failure by the Trustee to so notify 
the Company shall not relieve the Company of its obligations hereunder.  The 
Company shall defend any such claim and the Trustee shall cooperate in the 
defense of such claim.  The Trustee may have separate counsel and the Company 
shall pay the reasonable fees and expenses of such counsel.  The Company need 
not pay for any settlement made without its consent, which consent shall not 
be unreasonably withheld.


                                     -60-

<PAGE>

         The Company need not reimburse any expense or indemnify against any 
loss, liability or expense incurred by the Trustee through the Trustee's own 
willful misconduct, gross negligence or bad faith.

         To secure the Company's payment obligations in this Section 7.07, 
the Trustee shall have a Lien prior to the Notes on all money or property 
held or collected by the Trustee other than money or property held in trust 
to pay principal of, premium, if any, and interest on, particular Notes.

         The Company's payment obligations pursuant to this Section 7.07 
shall survive the resignation or removal of the Trustee and discharge of this 
Indenture.  Subject to any other rights available to the Trustee under 
applicable bankruptcy law, when the Trustee incurs expenses after the 
occurrence of a Default specified in Section 6.01(g) or Section 6.01(h) 
hereof, the expenses are intended to constitute expenses of administration 
under bankruptcy law.

         SECTION 7.08.   REPLACEMENT OF TRUSTEE.  (a)  No resignation or 
removal of the Trustee and no appointment of a successor Trustee pursuant to 
this Article VII shall become effective until the acceptance of appointment 
by the successor Trustee under this Section 7.08.

         (b)     The Trustee may resign at any time by giving written notice 
thereof to the Company.  If an instrument of acceptance by a successor 
Trustee shall not have been delivered to the Trustee within 30 calendar days 
after the giving of such notice of resignation, the resigning Trustee may 
petition any court of competent jurisdiction for the appointment of a 
successor Trustee.

         (c)     The Trustee may be removed at any time by Act of the Holders 
of a majority in principal amount of the outstanding Notes, delivered to the 
Trustee and to the Company.  If an instrument of acceptance by a successor 
Trustee shall not have been delivered to the Trustee within 30 calendar days 
after the giving of notice of removal, the Trustee being removed may petition 
any court of competent jurisdiction for the appointment of a successor 
Trustee.

         (d)     If at any time:

                 (i)     the Trustee shall fail to comply with Section 310(b) 
     of the Trust Indenture Act after written request therefor by the Company 
     or by any Holder who has been a bona fide Holder of a Note for at least 
     six months, unless the Trustee's duty to resign is stayed in accordance 
     with the provisions of Section 310(b) of the Trust Indenture Act; or

                 (ii)    the Trustee shall cease to be eligible under Section 
     7.10 hereof and shall fail to resign after written request therefor by 
     the Company or by any such Holder; or

                 (iii)   the Trustee shall become incapable of acting or a 
     decree or order for relief by a court having jurisdiction in the 
     premises shall have been entered in respect of the Trustee in an 
     involuntary case under the United States bankruptcy laws, as now or 
     hereafter constituted, or any other applicable Federal or state 
     bankruptcy, insolvency or similar law; or a decree or order 

                                     -61-

<PAGE>

     by a court having jurisdiction in the premises shall have been entered 
     for the appointment of a receiver, custodian, liquidator, assignee, 
     trustee, sequestrator (or other similar official) of the Trustee or of 
     its Property or affairs, or any public officer shall take charge or 
     control of the Trustee or of its Property or affairs for the purpose of 
     rehabilitation, conservation, winding up or liquidation; or

                 (iv)    the Trustee shall commence a voluntary case under the 
     United States bankruptcy laws, as now or hereafter constituted, or any 
     other applicable Federal or state bankruptcy, insolvency or similar law 
     or shall consent to the appointment of or taking possession by a 
     receiver, custodian, liquidator, assignee, trustee, sequestrator (or 
     other similar official) of the Trustee or its Property or affairs, or 
     shall make an assignment for the benefit of creditors, or shall admit in 
     writing its inability to pay its debts generally as they become due, or 
     shall take corporate action in furtherance of any such action,

then, in any such case, (i) the Company by a Board Resolution may remove the 
Trustee with respect to the Notes, or (ii) subject to Section 6.10 hereof, 
any Holder who has been a bona fide Holder of a Note for at least six months 
may, on behalf of such Holder and all others similarly situated, petition any 
court of competent jurisdiction for the removal of the Trustee and the 
appointment of a successor Trustee for the Notes.  If an instrument of 
acceptance by a successor Trustee shall not have been delivered to the 
Trustee within 30 calendar days after the giving of notice of removal, the 
Trustee being removed may petition any court of competent jurisdiction for 
the appointment of a successor Trustee.

         (e)     If the Trustee shall resign, be removed or become incapable 
of acting, or if a vacancy shall occur in the office of Trustee for any 
cause, the Company, by or pursuant to a Board Resolution, shall promptly 
appoint a successor Trustee.  If, within one year after such resignation, 
removal or incapability, or the occurrence of such vacancy, a successor 
Trustee shall be appointed by the Holders of a majority in principal amount 
of the outstanding Notes delivered to the Company and the retiring Trustee, 
the successor Trustee so appointed shall, forthwith upon its acceptance of 
such appointment in accordance with this Section 7.08, become the successor 
Trustee and to that extent replace any successor Trustee appointed by the 
Company. If no successor Trustee shall have been so appointed by the Company 
or the Holders and shall have accepted appointment in the manner hereinafter 
provided, any Holder that has been a bona fide Holder of a Note for at least 
six months may, subject to Section 6.10 hereof, on behalf of himself and all 
others similarly situated, petition any court of competent jurisdiction for 
the appointment of a successor Trustee.

         (f)     The Company shall give notice of each resignation and each 
removal of the Trustee and each appointment of a successor Trustee by mailing 
written notice of such resignation, removal and appointment by first class 
mail, postage prepaid, to the Holders as their names and addresses appear in 
the Security Register.  Each notice shall include the name of the successor 
Trustee with respect to the Notes and the address of its Corporate Trust 
Office.

                                     -62-

<PAGE>

         (g)     In the event of an appointment hereunder of a successor 
Trustee, each such successor Trustee so appointed shall execute, acknowledge 
and deliver to the Company and to the retiring Trustee an instrument 
accepting such appointment, and thereupon the resignation or removal of the 
retiring Trustee shall become effective and such successor Trustee, without 
any further act, deed or conveyance, shall become vested with all the rights, 
powers, trusts and duties of the retiring Trustee but, on request of the 
Company or the successor Trustee, such retiring Trustee shall, upon payment 
of its charges, execute and deliver an instrument transferring to such 
successor Trustee all the rights, powers and trusts of the retiring Trustee, 
and shall duly assign, transfer and deliver to such successor Trustee all 
Property and money held by such former Trustee hereunder, subject to its 
Lien, if any, provided for in Section 7.07 hereof.

         (h)     Upon request of any such successor Trustee, the Company 
shall execute any and all instruments for more fully and certainly vesting in 
and confirming to such successor Trustee all such rights, powers and trusts 
referred to in Section 7.08(g) hereof.

         (i)     No successor Trustee shall accept its appointment unless at 
the time of such acceptance such successor Trustee shall be qualified and 
eligible under this Article VII and under the Trust Indenture Act.

         SECTION 7.09.   SUCCESSOR TRUSTEE BY MERGER.  Any corporation into 
which the Trustee may be merged or converted or with which it may be 
consolidated, or any corporation resulting from any merger, conversion or 
consolidation to which the Trustee shall be a party, or any corporation 
succeeding to all or substantially all of the corporate trust business of the 
Trustee, shall be the successor of the Trustee hereunder; PROVIDED that such 
corporation shall be otherwise qualified and eligible under this Article VII 
and under the Trust Indenture Act, without the execution or filing of any 
paper or any further act on the part of any of the parties hereto.  In case 
any Notes shall have been authenticated, but not delivered, by the Trustee 
then in office, any successor by merger, conversion or consolidation to such 
authenticating Trustee may adopt such authentication and deliver the Notes so 
authenticated with the same effect as if such successor Trustee had itself 
authenticated such Notes.  In the event that any Notes shall not have been 
authenticated by such predecessor Trustee, any such successor Trustee may 
authenticate and deliver such Notes, in either its own name or that of its 
predecessor Trustee, with the full force and effect which this Indenture 
provides for the certificate of authentication of the Trustee.

         SECTION 7.10.   ELIGIBILITY; DISQUALIFICATION.  There shall at all 
times be a Trustee hereunder which shall be

                 (i)          a corporation organized and doing business under 
     the laws of the United States of America, any State or Territory thereof 
     or the District of Columbia, authorized under such laws to exercise 
     corporate trust powers, and subject to supervision or examination by 
     Federal, State, Territorial or District of Columbia authority, or

                                     -63-

<PAGE>

                 (ii)         a corporation or other Person organized and doing
     business under the laws of a foreign government that is permitted to act 
     as Trustee pursuant to a rule, regulation or order of the Commission, 
     authorized under such laws to exercise corporate trust powers, and 
     subject to supervision or examination by authority of such foreign 
     government or a political subdivision thereof substantially equivalent 
     to supervision or examination applicable to United States institutional 
     trustees,
     
in either case having a combined capital and surplus of at least $50,000,000.

         If such Person publishes reports of condition at least annually, 
pursuant to law or to the requirements of the aforesaid supervising or 
examining authority, then for the purposes of this Section 7.10, the combined 
capital and surplus of such corporation shall be deemed to be its combined 
capital and surplus as set forth in its most recent report of condition so 
published.  Neither the Company nor any Affiliate of the Company shall serve 
as Trustee hereunder.  If at any time the Trustee shall cease to be eligible 
to serve as Trustee hereunder pursuant to the provisions of this Section 
7.10, it shall resign immediately in the manner and with the effect specified 
in this Article VII.

         If the Trustee has or shall acquire any "conflicting interest" 
within the meaning of Section 310(b) of the Trust Indenture Act, the Trustee 
and the Company shall in all respects comply with the provisions of Section 
310(b) of the Trust Indenture Act.  Nothing herein shall prevent the Trustee 
from filing with the Commission the application referred to in the 
penultimate paragraph of Section 310(b) of the Trust Indenture Act.

         SECTION 7.11.   PREFERENTIAL COLLECTION OF CLAIMS AGAINST COMPANY.  
The Trustee shall comply with Section 311(a) of the Trust Indenture Act, 
excluding any creditor relationship listed in Section 311(b) of the Trust 
Indenture Act.  A Trustee who has resigned or been removed shall be subject 
to Section 311(a) of the Trust Indenture Act to the extent indicated therein.

                              ARTICLE VIII

                               DEFEASANCE

         SECTION 8.01.    COMPANY'S OPTION TO EFFECT LEGAL DEFEASANCE OR 
COVENANT DEFEASANCE.  The Company may elect, at its option, at any time, to 
have Section 8.02 or Section 8.03 hereof applied to the outstanding Notes (in 
whole and not in part) upon compliance with the conditions set forth below in 
this Article VIII. Such election shall be evidenced by a Board Resolution 
delivered to the Trustee and shall specify whether the Notes are being 
defeased to Stated Maturity or to a specified Redemption Date determined in 
accordance with the terms of this Indenture and the Notes.

         SECTION 8.02.    LEGAL DEFEASANCE AND DISCHARGE.  Upon the Company's 
exercise under Section 8.01 hereof, of its option to have this Section 8.02 
applied to the outstanding Notes (in whole and not in part), the Company 
shall be deemed to have been discharged from its obligations with respect to 
such Notes as provided in this Section 8.02 on and after the date the 
conditions set forth 


                                     -64-

<PAGE>

in Section 8.04 hereof are satisfied (hereinafter called "Legal Defeasance"). 
For this purpose, such Legal Defeasance means that the Company and the 
Subsidiary Guarantors shall be deemed to have paid and discharged the entire 
indebtedness represented by such Notes, which shall thereafter be deemed to 
be "outstanding" only for the purposes of Section 8.05 hereof and the other 
Sections of this Indenture referred to in (a) and (b) below, and to have 
satisfied all its other obligations under such Notes and this Indenture 
insofar as such Notes are concerned (and the Trustee, on demand of and at the 
expense of the Company, shall execute proper instruments acknowledging the 
same), subject to the following which shall survive until otherwise 
terminated or discharged hereunder:

         (a)     the rights of Holders of such Notes to receive, solely from the
     trust fund described in Section 8.04 hereof and as more fully set forth 
     in such Section 8.04 payments in respect of the principal of and any 
     premium and interest on such Notes when payments are due,

   
         (b)     the Company's and the Subsidiary Guarantors' obligations with 
     respect to such Notes under Sections 2.06, 2.07, 2.09, 4.02, 4.03 and 
     4.04 hereof and the Subsidiary Guarantees,
    

         (c)     the rights, powers, trusts, duties and immunities of the 
     Trustee under this Indenture and the Company's obligations in connection 
     therewith,

         (d)     Article III hereof, and

         (e)     this Article VIII.

         Subject to compliance with this Article VIII, the Company may 
exercise its option to have this Section 8.02 applied to the outstanding 
Notes (in whole and not in part) notwithstanding the prior exercise of its 
option to have Section 8.03 hereof applied to such Notes.

         SECTION 8.03.   COVENANT DEFEASANCE.  Upon the Company's exercise 
under Section 8.01 hereof of its option to have this Section 8.03 applied to 
the outstanding Notes (in whole and not in part), (i) the Company and the 
Subsidiary Guarantors shall be released from their obligations under Section 
5.01(iii), Sections 4.05 through 4.17, inclusive, and any covenant added to 
this Indenture subsequent to the date of this Indenture pursuant to Section 
9.01 hereof, (ii) the occurrence of any event specified in Section 6.01(c) or 
Section 6.01(d) hereof, with respect to any of Section 5.01(iii), Sections 
4.05 through 4.17, inclusive, and any covenant added to this Indenture 
subsequent to the date of this Indenture pursuant to Section 9.01 hereof, 
shall be deemed not to be or result in an Event of Default, in each case with 
respect to such Notes as provided in this Section 8.03 on and after the date 
the conditions set forth in Section 8.04 hereof are satisfied (hereinafter 
called "Covenant Defeasance") and the Notes shall thereafter be deemed not 
"outstanding" for the purposes of any direction, waiver consent or 
declaration or act of Holders (and the consequences of any thereof) in 
connection with such covenants, but shall continue to be deemed "outstanding" 
for all other purposes hereunder (it being understood that such Notes shall 
not be deemed outstanding for accounting purposes).  For this purpose, such 
Covenant Defeasance means that, with respect to such Notes, the Company and 
the Subsidiary Guarantors may omit to comply with and shall have no liability 
in 


                                     -65-

<PAGE>

respect of any term, condition or limitation set forth in any such specified 
Section (to the extent so specified in the case of Sections 6.01(c) and 
6.01(d) hereof), whether directly or indirectly, by reason of any reference 
elsewhere herein to any such Section or by reason of any reference in any 
such Section to any other provision herein or in any other document; but the 
remainder of this Indenture and such Notes shall be unaffected thereby.  In 
addition, upon the Company's exercise under Section 8.01 hereof of the option 
applicable to this Section 8.03 hereof, subject to the satisfaction of the 
conditions set forth in Section 8.04 hereof, Sections 6.01 (e) and 6.01(f) 
hereof shall thereafter not constitute Events of Default.

         SECTION 8.04.   CONDITIONS TO DEFEASANCE OR COVENANT DEFEASANCE.  The 
following shall be the conditions to the application of Section 8.02 or 
Section 8.03 hereof to the outstanding Notes:

         (a)     The Company or any Subsidiary Guarantor shall irrevocably have 
     deposited or caused to be deposited with the Trustee as trust funds in 
     trust for the purpose of making the following payments, specifically 
     pledged as security for, and dedicated solely to the benefits of the 
     Holders of such Notes, (i) money in an amount, or (ii) U.S. Government 
     Obligations which through the scheduled payment of principal and 
     interest in respect thereof in accordance with their terms will provide, 
     not later than one day before the due date of any payment, money in an 
     amount, or (iii) a combination thereof, in each case sufficient, in the 
     opinion of a nationally recognized firm of independent public 
     accountants expressed in a written certification thereof delivered to 
     the Trustee, to pay and discharge, and which shall be applied by the 
     Trustee (or any such other qualifying trustee) to pay and discharge, the 
     principal of, premium, if any, and any installment of interest on such 
     Notes on the Stated Maturity thereof or applicable Redemption Date, as 
     the case may be, in accordance with the terms of this Indenture and such 
     Notes.

         (b)     In the event of an election to have Section 8.02 hereof apply 
     to the outstanding Notes, the Company shall have delivered to the 
     Trustee an Opinion of Counsel stating that (i) the Company has received 
     from, or there has been published by, the Internal Revenue Service a 
     ruling or (ii) since the date of this Indenture, there has been a change 
     in the applicable Federal income tax law, in either case (i) or (ii) to 
     the effect that, and based thereon such opinion shall confirm that, the 
     Holders of such Notes will not recognize income, gain or loss for 
     Federal income tax purposes as a result of the deposit, Legal Defeasance 
     and discharge to be effected with respect to such Notes and will be 
     subject to Federal income tax on the same amount, in the same manner and 
     at the same times as would be the case if such deposit, Legal Defeasance 
     and discharge were not to occur.

         (c)     In the event of an election to have Section 8.03 hereof apply 
     to the outstanding Notes, the Company shall have delivered to the 
     Trustee an Opinion of Counsel to the effect that the Holders of such 
     Notes will not recognize income, gain or loss for Federal income tax 
     purposes as a result of the deposit and Covenant Defeasance to be 
     effected with respect to such Notes and will be subject to Federal 
     income tax on the same amount, in the same manner and at the same times 
     as would be the case if such deposit and Covenant Defeasance were not to 
     occur.

                                     -66-

<PAGE>

         (d)     No Default or Event of Default with respect to the outstanding 
     Notes shall have occurred and be continuing at the time of such deposit 
     (other than a Default or Event of Default resulting from the borrowing 
     of funds to be applied to such deposit) after giving effect thereto or, 
     with respect to a Default or Event of Default specified in Section 
     6.01(g) or Section 6.01(h), any time on or prior to the 123rd calendar 
     day after the date of such deposit (it being understood that this 
     condition shall not be deemed satisfied until after such 123rd calendar 
     day).

         (e)     Such Legal Defeasance or Covenant Defeasance shall not cause 
     the Trustee to have a conflicting interest within the meaning of the 
     Trust Indenture Act (assuming for the purpose of this clause (e) that 
     all Notes are in default within the meaning of such Act).

         (f)     Such Legal Defeasance or Covenant Defeasance shall not result 
     in a breach or violation of, or constitute a default under, any material 
     agreement or instrument (other than this Indenture) to which the Company 
     or any of its Subsidiaries is a party or by which the Company or any of 
     its Subsidiaries is bound.

         (g)     The Company shall have delivered to the Trustee an Officers' 
     Certificate stating that the deposit was not made by the Company with 
     the intent of preferring the Holders over any other creditors of the 
     Company or with the intent of defeating, hindering, delaying or 
     defrauding any other creditors of the Company.

         (h)     Such Legal Defeasance or Covenant Defeasance shall not result 
     in the trust arising from such deposit constituting an investment 
     company within the meaning of the Investment Company Act of 1940, as 
     amended, unless such trust shall be registered under such Act or exempt 
     from registration thereunder.

         (i)     The Company shall have delivered to the Trustee an Officers' 
     Certificate and an Opinion of Counsel, each stating that all conditions 
     precedent with respect to such Legal Defeasance or Covenant Defeasance 
     have been complied with.

   
         SECTION 8.05.   DEPOSITED MONEY AND U.S. GOVERNMENT OBLIGATIONS TO BE 
HELD IN TRUST; MISCELLANEOUS PROVISIONS.  All money and U.S. Government 
Obligations (including the proceeds thereof) deposited with the Trustee 
pursuant to Section 8.04 hereof in respect of the outstanding Notes shall be 
held in trust and applied by the Trustee, in accordance with the provisions 
of such Notes and this Indenture, to the payment, either directly or through 
any such Paying Agent as the Trustee may determine, to the Holders of such 
Notes, of all sums due and to become due thereon in respect of principal and 
any premium and interest, but money so held in trust need not be segregated 
from other funds except to the extent required by law.  The Company shall pay 
and indemnify the Trustee against any tax, fee or other charge imposed on or 
assessed against the U.S. Government Obligations deposited pursuant to 
Section 8.04 hereof or the principal and interest received in respect thereof 
other than any such tax, fee or other charge which by law is for the account 
of the Holders of outstanding Notes.
    
                                     -67-

<PAGE>

         Anything in this Article VIII to the contrary notwithstanding, the 
Trustee shall deliver or pay to the Company from time to time upon Company 
Order any money or U.S. Government Obligations held by it as provided in 
Section 8.04 hereof which, in the opinion of a nationally recognized firm of 
independent public accountants expressed in a written certification thereof 
delivered to the Trustee, are in excess of the amount thereof that would then 
be required to be deposited to effect the Legal Defeasance or Covenant 
Defeasance, as the case may be, with respect to the outstanding Notes.

   
         SECTION 8.06.   REINSTATEMENT.  If the Trustee or Paying Agent is 
unable to apply any money in accordance with this Article VIII with respect 
to any Notes by reason of any order or judgment of any court or governmental 
authority enjoining, restraining or otherwise prohibiting such application 
then the obligations under this Indenture and such Notes from which the 
Company has been discharged or released pursuant to Section 8.02 or 8.03 
hereof shall be revived and reinstated as though no deposit had occurred 
pursuant to this Article VIII with respect to such Notes, until such time as 
the Trustee or Paying Agent is permitted to apply all money held in trust 
pursuant to Section 8.05 hereof with respect to such Notes in accordance with 
this Article VIII; provided that if the Company or any Subsidiary Guarantor 
makes any payment of principal of or any premium or interest on any such Note 
following such reinstatement of its obligations, the Company or such 
Subsidiary Guarantor, as the case may be, shall be subrogated to the rights 
(if any) of the Holders of such Notes to receive such payment from the money 
so held in trust.
    

                                 ARTICLE IX

                                 AMENDMENTS
   
         SECTION 9.01.    WITHOUT CONSENT OF HOLDERS.  The Company, the 
Subsidiary Guarantors and the Trustee may, at any time, and from time to 
time, without notice to or consent of any Holder of Notes, enter into one or 
more indentures supplemental hereto or execute and deliver any Subsidiary 
Guarantee or amendment or supplement thereto, in form satisfactory to the 
Trustee, for any of the following purposes:
    

         (a)     to evidence the succession of another Person to the Company 
     and the assumption by such successor of the covenants of the Company 
     herein and contained in the Notes; or

   
         (b)     to add to the covenants of the Company or its Subsidiaries, 
     for the benefit of the Holders of all of the Notes, or to surrender any 
     right or power herein conferred upon the Company or its Subsidiaries; 
     or
    

         (c)     to add any additional Events of Default; or

         (d)     to provide for uncertificated Notes in addition to or in place
     of Certificated Notes; or

         (e)     to evidence and provide for the acceptance of appointment 
     hereunder of a successor Trustee; or

   
         (f)     to secure the Notes or the Subsidiary Guarantees; or
    

                                     -68-

<PAGE>

   
         (g)      to cure any ambiguity herein, or to correct or supplement 
     any provision hereof or the Subsidiary Guarantees which may be 
     inconsistent with any other provision hereof or to add any other 
     provisions with respect to matters or questions arising under this 
     Indenture; provided that such actions shall not adversely affect the 
     interests of the Holders of Notes in any material respect; or
    

         (h)     to comply with the requirements of the Commission in order to 
     effect or maintain the qualification of this Indenture under the Trust 
     Indenture Act; or

         (i)     to provide for assumption of a Subsidiary Guarantor's 
     obligations under its Subsidiary Guarantee upon a merger, consolidation, 
     sale, assignment, transfer, lease, conveyance or other disposition of 
     all or substantially all of the assets, of such Subsidiary Guarantor, in 
     compliance with Section 11.02; or

         (j)     to add or release a Subsidiary Guarantor in compliance with the
     provisions of Article XI.

   
         SECTION 9.02.   WITH CONSENT OF HOLDERS.  With the consent of the 
Holders of not less than a majority in principal amount of the outstanding 
Notes (which consent may, but need not, be given in connection with any 
tender offer or exchange offer for the Notes), by Act of said Holders 
delivered to the Company, each of the Subsidiary Guarantors and the Trustee, 
the Company, each of the Subsidiary Guarantors and the Trustee may enter into 
one or more indentures supplemental hereto or amendments or supplements to 
the Subsidiary Guarantees for the purpose of adding any provisions to or 
changing in any manner or eliminating any of the provisions of this Indenture 
or the Subsidiary Guarantees or of modifying in any manner the rights of the 
Holders (including Section 4.07 and Section 4.08 hereof); provided that no 
such supplement or amendment shall, without the consent of the Holder of each 
outstanding Note,
    

         (a)     reduce the principal amount of Notes whose Holders must consent
     to an amendment, supplement or waiver;

         (b)     reduce the principal of or change the Stated Maturity of any 
     Note or alter or waive any of the provisions with respect to the 
     redemption of the Notes, except as provided above with respect to 
     Sections 4.07 and 4.08 hereof;

         (c)     reduce the rate of or change the time for payment of interest, 
     including Defaulted Interest, on any Note;

         (d)     waive a Default or Event of Default in the payment of principal
     of or premium, if any, or interest on the Notes (except a rescission of 
     acceleration of the Notes by the Holders of at least a majority in 
     aggregate principal amount of the then outstanding Notes and a waiver of 
     the payment default that resulted from such acceleration);

         (e)     make any Note payable in money other than that stated in the
     Notes;


                                     -69-

<PAGE>

         (f)     make any change in the provisions of this Indenture relating 
     to waivers of past Defaults or the rights of Holders of Notes to receive 
     payments of principal of or interest on the Notes;

         (g)     waive a redemption payment with respect to any Note (other than
     a payment required by Section 4.07 or Section 4.08 hereof); 

         (h)     make any change in Section 6.04 or 6.07 hereof or in the 
     foregoing amendment and waiver provisions; or 

   
         (i)     modify any provisions of this Indenture or the Subsidiary 
     Guarantees relating to the relative ranking of the Notes or the 
     Subsidiary Guarantees in a manner adverse to the Holders thereof.

         It shall not be necessary for any Act of Holders under this Section 
9.02 to approve the particular form of any proposed supplement or amendment, 
but it shall be sufficient if such Act shall approve the substance thereof.
    

         After an amendment or supplement under this Section or a waiver 
under Section 6.04 becomes effective, the Company shall mail to the Holders 
of Notes affected thereby a notice briefly describing the amendment, 
supplement or waiver.  Any failure of the Company to mail such notice, or any 
defect therein, shall not, however, in any way impair or affect the validity 
of any such amended or supplemental Indenture or waiver.

   
         SECTION 9.03.   EFFECT OF SUPPLEMENTAL INDENTURES.  Upon the 
execution of any supplemental indenture or other amendment under this Article 
IX, this Indenture or the Subsidiary Guarantees, as the case may be, shall be 
modified in accordance therewith, and such supplemental indenture or other 
amendment shall form a part of this Indenture or the Subsidiary Guarantees, 
as the case may be, for all purposes; and every Holder of Notes theretofore 
or thereafter authenticated and delivered hereunder shall be bound thereby.

         SECTION 9.04.   COMPLIANCE WITH TRUST INDENTURE ACT.  Every amendment 
or supplement to this Indenture, the Subsidiary Guarantees or the Notes shall
comply with the Trust Indenture Act as then in effect.
    
         SECTION 9.05.   REVOCATION AND EFFECT OF CONSENTS AND WAIVERS.  A 
consent to an amendment, supplement or a waiver by a Holder of a Note shall 
bind the Holder and every subsequent Holder of such Note or portion of such 
Note that evidences the same debt as the consenting Holder's Note, even if 
notation of the consent or waiver is not made on such Note; provided that any 
such Holder or subsequent Holder may revoke the consent or waiver as to such 
Holder's Note or portion of such Note if the Trustee receives the notice of 
revocation before the date the amendment, supplement or waiver becomes 
effective.  After an amendment, supplement or waiver becomes effective 
pursuant to this Article IX, it shall bind every Holder.

         The Company may, but shall not be obligated to, fix a record date 
for the purpose of determining the Holders entitled to give their consent or 
take any other action described above or 


                                     -70-

<PAGE>

required or permitted to be taken pursuant to this Indenture.  If a record 
date is fixed, then notwithstanding the immediately preceding paragraph, 
those Persons who were Holders at such record date (or their duly designated 
proxies), and only those Persons, shall be entitled to give such consent or 
to revoke any consent previously given or to take any such action, whether or 
not such Persons continue to be Holders after such record date.  No such 
consent shall be valid or effective for more than 120 calendar days after 
such record date.

         SECTION 9.06.   NOTATION ON OR EXCHANGE OF NOTES.  If a supplemental 
indenture changes the terms of a Note, the Trustee may require the Holder 
thereof to deliver such Note to the Trustee.  The Trustee may place an 
appropriate notation on such Note regarding the changed terms and return it 
to the Holder. Alternatively, if the Company or the Trustee so determines, 
the Company in exchange for such Note shall issue and the Trustee shall 
authenticate a new Note that reflects the changed terms.  Failure to make the 
appropriate notation or to issue a new Note shall not affect the validity of 
such amendment or supplement.

   
         SECTION 9.07.   TRUSTEE TO EXECUTE SUPPLEMENTAL INDENTURES.  The 
Trustee shall execute any supplemental indenture or other amendment 
authorized pursuant to this Article IX if such supplemental indenture does 
not adversely affect the rights, duties, liabilities or immunities of the 
Trustee.  If it does, the Trustee may, but shall not be required to, execute 
such supplemental indenture or other amendment.  In executing any 
supplemental indenture or other amendment, the Trustee shall be entitled to 
receive indemnity reasonably satisfactory to it and to receive, and (subject 
to Section 7.01 hereof) shall be fully protected in relying upon, an 
Officers' Certificate (which need only cover the matters set forth in clause 
(a) below) and an Opinion of Counsel provided by the Company stating that:

         (a)     such supplemental indenture or other amendment is authorized
     or permitted by this Indenture and that all conditions precedent to the 
     execution, delivery and performance of such supplemental indenture have 
     been satisfied;

         (b)     the Company or any Subsidiary Guarantor, as the case may be,
     has all necessary corporate power and authority to execute and deliver 
     the supplemental indenture or other amendment and that the execution, 
     delivery and performance of such supplemental indenture or other 
     amendment has been duly authorized by all necessary corporate action of 
     the Company or such Subsidiary Guarantor;

         (c)     the execution, delivery and performance of the supplemental 
     indenture or other amendment do not conflict with, or result in the breach
     of or constitute a default under any of the terms, conditions or provisions
     of (i) this Indenture, (ii) the charter documents and by-laws of the 
     Company or such Subsidiary Guarantor, or (iii) any material agreement or 
     instrument to which the Company or such Subsidiary Guarantor is subject;

         (d)     to the best knowledge and belief of legal counsel writing such
     Opinion of Counsel, the execution, delivery and performance of the 
     supplemental indenture or other amendment do not conflict with, or result 
     in the breach of any of the terms, conditions or provisions of (i) any law
     or regulation applicable to the Company or such Subsidiary Guarantor, or
     (ii) any material order, writ, injunction or decree of any court or 
     governmental instrumentality applicable to the Company or such Subsidiary
     Guarantor;
    
                                     -71-

<PAGE>

   
         (e)     such supplemental indenture or other agreement has been duly
     and validly executed and delivered by the Company or such Subsidiary 
     Guarantor, and this Indenture or Subsidiary Guarantee, as the case may be,
     together with such supplemental indenture or other agreement constitutes 
     a legal, valid and binding obligation of the Company or such Subsidiary 
     Guarantor enforceable against such Person in accordance with its terms, 
     except as such enforceability may be limited by applicable bankruptcy, 
     insolvency or similar laws affecting the enforcement of creditors' rights 
     generally and general equitable principles; and

         (f)     this Indenture or Subsidiary Guarantee, as the case may be,
     together with such amendment or supplement complies with the Trust 
     Indenture Act.

         SECTION 9.08.   EFFECT ON SENIOR INDEBTEDNESS.  No supplemental 
indenture or amendment to the Subsidiary Guarantee shall adversely affect 
the rights of holders of Senior Indebtedness under Article X hereof or the 
holders of Guarantor Senior Indebtedness under Sections 4, 5, 6, 7, 8, 9, 10, 
11, 12 or 15 of the Subsidiary Guarantees unless expressly consented to in 
writing by or on behalf of such holders (or by any specified percentage 
of holders of a class of Senior Indebtedness or Guarantor Senior 
Indebtedness, as the case may be, required to consent thereto pursuant to the 
terms of the agreement or instrument creating, evidencing or governing such 
Senior Indebtedness or Guarantor Senior Indebtedness, as the case may be), in 
which event such supplemental indenture or amendment shall be binding on all 
successors and assigns of such holders and on all persons who become holders 
of such Senior Indebtedness or Guarantor Senior Indebtedness issued after the 
date of such amendment or modification. 
    
                                 ARTICLE X

                                SUBORDINATION
   

         SECTION 10.01.   AGREEMENT TO SUBORDINATE.  The Company agrees, and 
each Holder by accepting a Note agrees, that the Indebtedness evidenced by 
the Note and the payment of the principal of (and premium, if any, on) and 
interest on, the Note or the purchase by the Company pursuant to Sections 
4.07 and 4.08 hereof of any of the foregoing is expressly made subordinate 
and subject in right of payment, to the extent and in the manner provided in 
this Article X, to the prior payment in full of all Senior Indebtedness 
(whether outstanding on the date hereof or hereafter created, incurred, 
assumed or guaranteed), and that the subordination is for the benefit of the 
holders of Senior Indebtedness.  This Article X shall constitute a continuing 
offer to all Persons who become holders of, or continue to hold, Senior 
Indebtedness, and such provisions are made for the benefit of the holders of 
Senior Indebtedness. 
    

         SECTION 10.02.   LIQUIDATION; DISSOLUTION; BANKRUPTCY.  Upon any 
distribution to creditors of the Company in a liquidation or dissolution of 
the Company or in a bankruptcy, reorganization, insolvency, receivership or 
similar proceeding relating to the Company or its property, in an assignment 
for the benefit of creditors or any marshaling of the Company's assets and 
liabilities:

         (a)     holders of Senior Indebtedness shall be entitled to receive 
     payment in full in cash of all Obligations due in respect of such Senior 
     Indebtedness (including interest after the commencement of any such 
     proceeding at the rate specified in the applicable Senior Indebtedness) 
     before Holders shall be entitled to receive any payment with respect to 
     principal of (or premium, if any, on) or interest on the Notes or on 
     account of the purchase, redemption or other acquisition of the Notes 
     (including pursuant to an Asset Sale Offer or Change of Control Offer) 
     (except that Holders may receive (i) securities that are subordinated to 
     at least the same extent as the Notes are subordinated

                                     -72-

<PAGE>

     to (A) Senior Indebtedness and (B) any securities issued in exchange for 
     Senior Indebtedness and (ii) payments and other distributions made from 
     any defeasance trust created pursuant to Section 8.01 hereof); and

         (b)     until all Obligations with respect to Senior Indebtedness (as 
     provided in subsection (a) above) are paid in full in cash, any 
     distribution to which Holders would be entitled but for this Article 
     shall be made to holders of Senior Indebtedness (except that Holders may 
     receive (i) securities that are subordinated to at least the same extent 
     as the Notes to (A) Senior Indebtedness and (B) any securities issued in 
     exchange for Senior Indebtedness and (ii) payments and other 
     distributions made from any defeasance trust created pursuant to Section 
     8.01 hereof), as their interests may appear.

         SECTION 10.03.   DEFAULT ON DESIGNATED SENIOR INDEBTEDNESS.  The 
Company may not make any payment or distribution to the Trustee or any Holder 
in respect of Obligations with respect to the Notes and may not acquire from 
the Trustee or any Holder any Notes for cash or property (other than (i) 
securities that are subordinated to at least the same extent as the Notes to 
(A) Senior Indebtedness and (B) any securities issued in exchange for Senior 
Indebtedness and (ii) payments and other distributions made from any 
defeasance trust created pursuant to Section 8.01 hereof) until all principal 
and other Obligations with respect to the Senior Indebtedness have been paid 
in full if:

         (a)     a default in the payment of any principal, premium, if any, or
     interest with respect to Designated Senior Indebtedness occurs and is 
     continuing beyond any applicable grace period in the agreement, 
     indenture or other document governing such Designated Senior 
     Indebtedness; or

         (b)     a default, other than such payment default, on Designated 
     Senior Indebtedness occurs and is continuing that then permits holders 
     of such Designated Senior Indebtedness to accelerate its maturity and 
     the Trustee receives a notice of such default (a "Payment Blockage 
     Notice") from a Person who may give it pursuant to Section 10.11 hereof. 
      If the Trustee receives any such Payment Blockage Notice, no subsequent 
     Payment Blockage Notice shall be effective for purposes of this Section 
     10.03 unless and until at least 360 days shall have elapsed since the 
     effectiveness of the immediately prior Payment Blockage Notice.  No 
     default specified in this clause (b) that existed or was continuing on 
     the date of delivery of any Payment Blockage Notice to the Trustee shall 
     be, or be made, the basis for a subsequent Payment Blockage Notice.

         The Company may and shall resume payments on and distributions in 
respect of the Notes and may acquire them upon the earlier of:

         (i)     in the case of a default referred to in Section 10.03(a),
     the date upon which such default is cured or waived, or

         (ii)    in the case of a default referred to in Section 10.03(b) 
     hereof, the earlier of the date on which such default is cured or waived
     or 179 days after the date on which the applicable 


                                     -73-

<PAGE>

     Payment Blockage Notice is received, unless the maturity of such
     Designated Senior Indebtedness has been accelerated,

if, and only if, this Article X otherwise permits the payment, distribution 
or acquisition at the time of such payment or acquisition.

         SECTION 10.04.  ACCELERATION OF NOTES.  If payment of the Notes is 
accelerated because of an Event of Default, the Company shall promptly notify 
the Representatives of holders of Designated Senior Indebtedness and 
Designated Guarantor Senior Indebtedness of the acceleration.

         SECTION 10.05.  WHEN DISTRIBUTION MUST BE PAID OVER.  In the event 
that the Trustee or any Holder receives any payment of any Obligations with 
respect to the Notes at a time when the Trustee or such Holder, as 
applicable, has actual knowledge that such payment is prohibited by Section 
10.03 hereof, such payment shall be held by the Trustee or such Holder, in 
trust for the benefit of, and shall be paid forthwith over and delivered, 
upon written request, to, the holders of Senior Indebtedness as their 
interests may appear or their Representative under the indenture or other 
agreement (if any) pursuant to which Senior Indebtedness may have been 
issued, for application to the payment of all Obligations with respect to 
Senior Indebtedness remaining unpaid to the extent necessary to pay such 
Obligations in full in accordance with their terms, after giving effect to 
any concurrent payment or distribution to or for the holders of Senior 
Indebtedness.

         With respect to the holders of Senior Indebtedness, the Trustee 
undertakes to perform only such obligations on the part of the Trustee as are 
specifically set forth in this Article X, and no implied covenants or 
obligations with respect to the holders of Senior Indebtedness shall be read 
into this Indenture against the Trustee.  The Trustee shall not be deemed to 
owe any fiduciary duty to the holders of Senior Indebtedness, and shall not 
be liable to any such holders if the Trustee shall pay over or distribute to 
or on behalf of Holders or the Company or any other Person money or assets to 
which any holders of Senior Indebtedness shall be entitled by virtue of this 
Article X, except if such payment is made as a result of the willful 
misconduct or gross negligence of the Trustee.

         SECTION 10.06.   NOTICE BY COMPANY.  The Company shall promptly notify 
the Trustee and the Paying Agent of any facts known to the Company that would 
cause a payment of any Obligations with respect to the Notes to violate this 
Article X, but failure to give such notice shall not affect the subordination 
of the Notes to the Senior Indebtedness as provided in this Article X.

         SECTION 10.07.   SUBROGATION.  After all Senior Indebtedness is paid 
in full and until the Notes are paid in full, Holders shall be subrogated 
(equally and ratably with all other Indebtedness PARI PASSU with the Notes) 
to the rights of holders of Senior Indebtedness to receive distributions 
applicable to Senior Indebtedness to the extent that distributions otherwise 
payable to the Holders have been applied to the payment of Senior 
Indebtedness.  A distribution made under this Article X to holders of Senior 
Indebtedness that otherwise would have been made to Holders is not, as 
between the Company and Holders, a payment by the Company on the Notes.


                                     -74-
<PAGE>

     SECTION 10.08. RELATIVE RIGHTS.  This Article X defines the relative 
rights of Holders and holders of Senior Indebtedness.  Nothing in this 
Indenture shall:

          (i)   impair, as between the Company and Holders, the obligation of 
     the Company, which is absolute and unconditional, to pay principal of, 
     premium, if any, on and interest on the Notes in accordance with their 
     terms;

          (ii)  affect the relative rights of Holders and creditors of the 
     Company other than their rights in relation to holders of Senior 
     Indebtedness; or

          (iii) prevent the Trustee or any Holder from exercising its available
     remedies upon a Default or Event of Default, subject to the rights of 
     holders and owners of Senior Indebtedness to receive distributions and 
     payments otherwise payable to Holders.

     If the Company fails because of this Article X to pay principal of, 
premium, if any, on or interest on a Note on the due date, the failure is still
a Default or Event of Default.

     SECTION 10.09.  NO WAIVER OF SUBORDINATION.  (a) No right of any holder 
of Senior Indebtedness to enforce the subordination of the Indebtedness 
evidenced by the Notes shall be impaired by any act or failure to act by the 
Company or any Holder or by the failure of the Company or any Holder to 
comply with this Indenture.

     (b) Without in any way limiting the generality of paragraph (a) of this 
Section, the holders of any Senior Indebtedness, in accordance with the terms 
of the instrument or agreement evidencing their Senior Indebtedness, may, at 
any time and from time to time, without the consent of or notice to the 
Trustee or the Holders, without incurring responsibility to the Holders and 
without impairing or releasing the subordination or other benefits provided in 
this Article X, or the obligations hereunder of the Holders to the holders of 
Senior Indebtedness, do any one or more of the following: (i) change the 
manner, place or terms of payment or extend the time of payment of, or renew, 
exchange, amend, increase or alter, Senior Indebtedness or the terms of any 
instrument evidencing the same or any agreement under which Senior 
Indebtedness is outstanding or any liability of any obligor thereon (unless 
such change, extension, amendment, increase or other alteration results in 
such Indebtedness no longer being Senior Indebtedness as defined in this 
Indenture); (ii) sell, exchange, release or otherwise deal with any Property 
pledged, mortgaged or otherwise securing Senior Indebtedness; (iii) settle or 
compromise any Senior Indebtedness or any liability of any obligor thereon or 
release any Person liable in any manner for the collection of Senior 
Indebtedness; and (iv) exercise or refrain from exercising any rights against 
the Company and any other Person.

     SECTION 10.10. DISTRIBUTION OR NOTICE TO REPRESENTATIVE.  Whenever a 
distribution is to be made or a notice given to holders of Senior Indebtedness,
the distribution may be made and the notice given to their Representative.

     Upon any payment or distribution of assets of the Company referred to in 
this Article X, the Trustee and the Holders shall be entitled to rely upon any
order or decree made by any court of competent jurisdiction or upon any 
certificate of such Representative or of the liquidating trustee or agent or 
other Person making any distribution to the Trustee or to the Holders for the 
purpose of ascertaining the Persons entitled to participate in such 
distribution, the holders of the Senior Indebtedness and other Indebtedness 
of the Company, the amount thereof or payable thereon, the amount or amounts 
paid or distributed thereon and all other facts pertinent thereto or to this 
Article X.

     The Trustee shall be entitled to rely on the delivery to it of a written 
notice by a Person representing himself to be a holder of Senior Indebtedness 
(or a trustee or agent on behalf of such holder) to establish that such notice
has been given by a holder of Senior Indebtedness (or a trustee or agent on 
behalf of any such holder).  In the event that the Trustee determines in good
faith that further evidence is required with respect to the right of any Person
as a holder of Senior Indebtedness to participate in any payment or 
distribution pursuant to this Article X, the Trustee may request such Person 
to furnish evidence to the reasonable satisfaction of the Trustee as to the 
amount of Senior Indebtedness held by such Person, the extent to which such 
Person is entitled to participate in such 




                                   -75-


<PAGE>

payment or distribution and any other facts pertinent to the rights of such 
Person under this Article X, and if such evidence is not furnished, the 
Trustee may defer any payment which it may be required to make for the benefit
of such Person pursuant to the terms of this Indenture pending judicial 
determination as to the rights of such Person to receive such payment.

     SECTION 10.11. RIGHTS OF TRUSTEE AND PAYING AGENT.  Notwithstanding the 
provisions of this Article X or any other provision of this Indenture, the 
Trustee shall not be charged with knowledge of the existence of any facts 
that would prohibit the making of any payment or distribution by the Trustee, 
and the Trustee and the Paying Agent may continue to make payments on the 
Notes, unless the Trustee shall have received at its Corporate Trust Office 
at least two Business Days prior to the date of such payment written notice 
of facts that would cause the payment of any Obligations with respect to the 
Notes to violate Article X or XI. Only the holders of Designated Senior 
Indebtedness or a Representative thereof may give the notice. Nothing in 
Article X or XI shall impair the claims of, or payments to, the Trustee under 
or pursuant to Section 7.07 hereof.

     The Trustee in its individual or any other capacity may hold Senior 
Indebtedness with the same rights it would have if it were not Trustee.  Any 
Paying Agent may do the same with like rights.

     SECTION 10.12. AUTHORIZATION TO EFFECT SUBORDINATION.  Each Holder of a 
Note by the Holder's acceptance thereof authorizes and directs the Trustee on 
the Holder's behalf to take such action as may be necessary or appropriate to 
effectuate the subordination as provided in this Article X, and appoints the 
Trustee to act as the Holder's attorney-in-fact for any and all such purposes.
If the Trustee does not file a proper proof of claim or proof of debt in the 
form required in any judicial proceeding relative to the Company (or any other
obligor upon the Notes), its creditors or its property at least 30 days before
the expiration of the time to file such claim, any Representative is hereby 
authorized to file an appropriate claim for and on behalf of the Holders of 
the Notes.

     SECTION 10.13. AMENDMENTS.  The provisions of this Article X shall not 
be amended or modified in a manner materially adverse to the Holders of Senior
Indebtedness without the written consent of the holders of all Designated 
Senior Indebtedness.

   
                                   ARTICLE XI 

                             SUBSIDIARY GUARANTEES

     SECTION 11.01.  ADDITION OF SUBSIDIARY GUARANTORS. 

          (a)  The Company agrees to cause each Subsidiary to execute and 
     deliver a Subsidiary Guarantee in the form of Exhibit C attached 
     hereto pursuant to which such Person guarantees the payment of the 
     Notes at or before such Person incurs any Indebtedness other than 
     Indebtedness described in Section 4.12(b)(iv) or (vii).

          (b)  Any Person that was not a Subsidiary Guarantor on the date of 
     this Indenture may become a Subsidiary Guarantor by executing and 
     delivering to the Trustee (i) a Subsidiary Guarantee in the form of
     Exhibit C attached hereto and (ii) an Opinion of Counsel and Officers'
     Certificate to the effect that such supplemental indenture has been duly
     authorized and executed by such Person and constitutes the legal, valid,
     binding and enforceable obligation of such Person (subject to such
     customary exceptions concerning creditors' rights and equitable principles
     as may 
    


                                   -76-


<PAGE>

   
     be acceptable to the Trustee in its discretion and provided that no 
     opinion need be rendered concerning the enforceability of the Subsidiary
     Guarantee).

     SECTION 11.02.  RELEASE OF A SUBSIDIARY GUARANTOR.

          (a)  Upon the sale or other disposition (by merger or otherwise) of
     a Subsidiary Guarantor (or all or substantially all of its assets) to a 
     Person other than the Company or another Subsidiary Guarantor and pursuant
     to a transaction that is otherwise in compliance with this Indenture 
     (including as described in Section 11.03 or Article V), such Subsidiary 
     Guarantor shall be deemed released from all of its Subsidiary Guarantees
     and related obligations in this Indenture; PROVIDED, HOWEVER, that any such
     termination shall occur only to the extent that all obligations of such 
     Subsidiary Guarantor under all of its guarantees of, and under all of its
     pledges of assets or other security interests which secure, other 
     Indebtedness of the Company or any Subsidiary shall also terminate or be
     released upon such sale or other disposition.
    

          (b)  Each Subsidiary Guarantor that is designated as an Unrestricted
     Subsidiary by the Company in accordance with the provisions of this 
     Indenture shall be deemed released from all of its Subsidiary Guarantees
     and related obligations in this Indenture for so long as it remains an 
     Unrestricted Subsidiary.

          (c)  The Trustee shall deliver an appropriate instrument evidencing 
     such release upon receipt of a request by the Company accompanied by an 
     Officers' Certificate and an Opinion of Counsel certifying that such sale
     or other disposition was made by the Company or the Subsidiary Guarantor,
     as the case may be, in accordance with the provisions of this  Indenture.
     Any Subsidiary Guarantor not so released remains liable for the full amount
     of principal of and interest on the Notes as provided in this Article XI.

   
          (d)  Any Subsidiary Guarantor not released in accordance with this 
     Section 11.02 shall remain liable for the full amount of principal of (and
     premium, if any, on) and interest on the Securities as provided in this 
     Article XI and the Subsidiary Guarantees.

     SECTION 11.03. SUBSIDIARY GUARANTORS MAY CONSOLIDATE, ETC., ON CERTAIN
                    TERMS.

          (a)  Except as set forth in Articles IV and V, nothing contained in 
     this Indenture or in any of the Notes shall prevent any consolidation or 
     merger of a Subsidiary Guarantor, with or into the Company or another 
     Subsidiary Guarantor or shall prevent any sale, assignment, transfer, 
     lease, conveyance or other disposition of the property of a Subsidiary 
     Guarantor as an entirety or substantially as an entirety, to the Company
     or another Subsidiary Guarantor.

          (b)  Except as set forth in Articles IV and V hereof, nothing 
     contained in this Indenture or in any of the Notes shall prevent any 
     consolidation or merger of a Subsidiary Guarantor with or into a Person
     other than the Company or a Subsidiary Guarantor (whether or not affiliated
     with the Subsidiary Guarantor), or successive consolidations or mergers in
     which a Subsidiary Guarantor or its successor or successors shall be a
     party or parties, or shall prevent any sale, assignment, transfer, lease,
     conveyance or other disposition of all or substantially all of the property
     of a Subsidiary Guarantor, to a Person other than the Company or another 
     Subsidiary Guarantor (whether or not affiliated with the Subsidiary 
     Guarantor); PROVIDED, that (i) if the surviving Person is not the Company 
     or a Subsidiary Guarantor, the surviving corporation agrees to assume such
     Subsidiary Guarantor's Subsidiary Guarantee and all its obligations 
     pursuant to this Indenture (except to the extent that Section 11.02 would
     result in the release of such Subsidiary Guarantee), (ii) immediately 
     after giving effect to such transaction no Default or Event of Default 
     would exist or be continuing, and (iii) each Subsidiary Guarantor hereby
     covenants and agrees that, upon any such consolidation, merger, sale, 
     conveyance or other disposition, such Subsidiary Guarantor's Subsidiary 
     Guarantee, and the due and punctual performance and observance of all of
     the covenants and conditions of this Indenture to be performed by such 
     Subsidiary Guarantor, shall be expressly assumed (in the event that the
     Subsidiary Guarantor is not the surviving corporation in a merger), by 
     supplemental indenture, Subsidiary Guarantee or other instrument 
     reasonably satisfactory in form to the Trustee, executed and delivered 
     to the Trustee, by such Person formed by such consolidation, or into 
     which the Subsidiary Guarantor shall have merged, or by the Person that
     shall have acquired such Property (except to the extent Section 11.02 
     would result in the release of such Subsidiary Guarantee, in which case
     such surviving Person or transferee of such Property shall not have to
     execute any such supplemental indenture, Subsidiary Guarantee or other
     instrument and shall not have to assume such Subsidiary Guarantor's 
     Subsidiary Guarantee).  In the case of any such consolidation, merger,
     sale, conveyance or other disposition and upon the assumption by 
     the successor Person, by supplemental indenture executed and delivered to
     the Trustee and reasonably satisfactory in form to the Trustee of the due
     and punctual performance of all of the covenants and conditions of this 
     Indenture to be performed by the Subsidiary Guarantor, such successor 
     Person shall succeed to and be substituted for the Subsidiary Guarantor
     with the same effect as if it had been named herein as the initial 
     Subsidiary Guarantor.

SECTION 11.04. SUBORDINATION OF SUBSIDIARY GUARANTEES.

     The obligations of the Subsidiary Guarantors in respect of the payment 
of the Notes are subordinated to the payment of Guarantor Senior Indebtedness 
in the manner and to the extent set forth in the Subsidiary Guarantees.
    



                                     -77-
<PAGE>

                                 ARTICLE XII

                                MISCELLANEOUS

     SECTION 12.01.  TRUST INDENTURE ACT CONTROLS.  If and to the extent that 
any provision of this Indenture limits, qualifies or conflicts with the 
duties imposed by, or with another provision (an "incorporated provision") 
included in this Indenture by operation of, Sections 310 to 318, inclusive, 
of the Trust Indenture Act, such imposed duties or incorporated provision 
shall control.

     SECTION 12.02.  NOTICES.  Any notice or communication shall be in writing 
and delivered in person or mailed by first class mail, postage prepaid, 
addressed as follows: if to the Company or any Subsidiary Guarantor:  400 
West Illinois, 10th Floor, Midland, Texas  79701, Attention: Chief Financial 
Officer; if to the Trustee: State Street Bank and Trust Company, Two 
International Place, 4th Floor, Boston, Massachusetts  02110, Attention: 
Corporate Trust Department.

     The Company, the Subsidiary Guarantors or the Trustee, by notice to the 
other, may designate additional or different addresses for subsequent notices 
or communications.  Any notice or communication mailed to a Holder shall be 
sent to the Holder by first class mail, postage prepaid, at the Holder's 
address as it appears in the Security Register and shall be duly given if so 
sent within the time prescribed. Failure to mail a notice or communication to 
a Holder or any defect in it shall not affect its sufficiency with respect to 
other Holders.  If a notice or communication is mailed to the Company, the 
Trustee or a Holder in the manner provided above, it is duly given, whether 
or not the addressee receives it.  In case by reason of the suspension of 
regular mail service or by reason of any other cause it shall be 
impracticable to give notice by mail to Holders, then such notification as 
shall be made with the approval of the Trustee shall constitute a sufficient 
notification for every purpose hereunder.

     SECTION 12.03.  CERTIFICATE AND OPINION AS TO CONDITIONS PRECEDENT.  Upon 
any request or application by the Company or any Subsidiary Guarantor to the 
Trustee to take or refrain from taking any action under this Indenture, the 
Company or such Subsidiary Guarantor shall furnish to the Trustee: (a) an 
Officers' Certificate stating that, in the opinion of the signers, all 
conditions precedent, if any, provided for in this Indenture relating to the 
proposed action have been complied with; and 


                                     -78-

<PAGE>

(b) an Opinion of Counsel stating that, in the opinion of such counsel, all 
such conditions precedent have been complied with.

     SECTION 12.04.  STATEMENTS REQUIRED IN CERTIFICATE OR OPINION.  Each 
certificate or opinion with respect to compliance with a covenant or 
condition provided for in this Indenture (other than pursuant to Section 4.19 
hereof) shall include: (a) a statement that the individual making such 
certificate or opinion has read such covenant or condition; (b) a brief 
statement as to the nature and scope of the examination or investigation upon 
which the statements or opinions contained in such certificate or opinion are 
based; (c) a statement that, in the opinion of such individual, such person 
has made such examination or investigation as is necessary to enable such 
person to express an informed opinion as to whether or not such covenant or 
condition has been complied with; and (d) a statement as to whether or not, 
in the opinion of such individual, such covenant or condition has been 
complied with.

     SECTION 12.05.  RULES BY TRUSTEE, PAYING AGENT AND REGISTRAR.  The 
Trustee may make reasonable rules for action by or a meeting of Holders, and 
any Registrar and Paying Agent may make reasonable rules for their functions; 
provided that no such rule shall conflict with terms of this Indenture or the 
Trust Indenture Act.

     SECTION 12.06.  PAYMENTS ON BUSINESS DAYS.  If a payment hereunder is 
scheduled to be made on a date that is not a Business Day, payment shall be 
made on the next succeeding day that is a Business Day, and no interest shall 
accrue with respect to that payment during the intervening period.  If a 
regular record date is a date that is not a Business Day, such record date 
shall not be affected.

     SECTION 12.07.  GOVERNING LAW.  THIS INDENTURE AND THE NOTES SHALL BE 
GOVERNED BY, AND CONSTRUED IN ACCORDANCE WITH, THE LAWS OF THE STATE OF NEW 
YORK APPLICABLE TO AGREEMENTS MADE AND TO BE PERFORMED IN SAID STATE.

   
     SECTION 12.08.  NO RECOURSE AGAINST OTHERS.  No director, officer, 
employee, incorporator or stockholder of the Company or any Subsidiary 
Guarantor, as such, shall have any liability for any obligations of the 
Company or any Subsidiary Guarantor under the Notes, the Subsidiary 
Guarantees or this Indenture or for any claim based on, in respect of, or by 
reason of, such obligations or their creation, solely by reason of its status 
as a director, officer, employee, incorporator or stockholder of the Company 
or any Subsidiary Guarantor.  By accepting a Note, each Holder waives and 
releases all such liability (but only such liability) as part of the 
consideration for issuance of such Note to such Holder.
    

     SECTION 12.09.  SUCCESSORS.  All agreements of the Company and the 
Subsidiary Guarantors in this Indenture and the Notes shall bind its 
successors and assigns whether so expressed or not.  All agreements of the 
Trustee in this Indenture shall bind its successors and assigns whether so 
expressed or not.


                                     -79-

<PAGE>

     SECTION 12.10.  COUNTERPARTS.  This Indenture may be executed in any 
number of counterparts and by the parties thereto in separate counterparts, 
each of which when so executed shall be deemed to be an original and all of 
which taken together shall constitute one and the same agreement.

     SECTION 12.11.  TABLE OF CONTENTS; HEADINGS.  The table of contents, 
cross-reference table and headings of the Articles and Sections of this 
Indenture have been inserted for convenience of reference only, are not 
intended to be considered a part hereof and shall not modify or restrict any 
of the terms or provisions hereof.

     SECTION 12.12.  SEVERABILITY.  In case any provision in this Indenture 
or in the Notes shall be invalid, illegal or unenforceable, the validity, 
legality and enforceability of the remaining provisions shall not in any way 
be affected or impaired thereby.

     SECTION 12.13.  FURTHER INSTRUMENTS AND ACTS.  Upon request of the 
Trustee, the Company and the Subsidiary Guarantors will execute and deliver 
such further instruments and do such further acts as may be reasonably 
necessary or proper to carry out more effectively the purposes of this 
Indenture.

     IN WITNESS WHEREOF, the parties hereto have caused this Indenture to be 
duly executed as of the day and year first above written.

                                       COSTILLA ENERGY, INC.

                                       By
                                         -----------------------------------
                                       Name:
                                       Title:
   
                                       STATE STREET BANK AND TRUST COMPANY, 
                                        as Trustee

                                       By
                                         -----------------------------------
                                       Name:
                                       Title:
    









                                     -80-

<PAGE>

   
STATE OF TEXAS                    )
                                  )         SS.:
COUNTY OF HARRIS                  )
    

     On the __ day of ______________, 1996, before me personally came 
_______________________, to me known, who, being by me duly sworn, did depose 
and say that he is ______________________ of Costilla Energy, Inc., one of 
the corporations described in and which executed the foregoing instrument, 
and that he signed his name thereto by authority of the Board of Directors of 
said corporation.

                                     --------------------------------------
                                                Notary Public
   
                                                State of Texas
                                                My commission expires 
                                                                      -----
    

[Seal]


   
STATE OF TEXAS                    )
                                  )         SS.:
COUNTY OF HARRIS                  )
    

     On the ____ day of __________________, 1996, before me personally came 
________________________, to me known, who, being by me duly sworn, did 
depose and say that ______ is ______________________ of State Street Bank and 
Trust Company, one of the corporations described in and which executed the 
foregoing instrument, and that he signed his name thereto by authority of the 
Board of Directors of said corporation.

                                  --------------------------------------
                                           Notary Public
   
                                  State of Texas
                                  My commission expires 
                                                        ----------------

[Seal]
    





                                     -81-
<PAGE>


                                                                     EXHIBIT A

                           FORM OF FACE OF GLOBAL NOTE

                              COSTILLA ENERGY, INC.

No. ______                                               CUSIP No. ___________

     THIS NOTE IS A GLOBAL NOTE WITHIN THE MEANING OF THE INDENTURE 
     HEREINAFTER REFERRED TO.

     UNLESS THIS NOTE IS PRESENTED BY AN AUTHORIZED REPRESENTATIVE OF THE 
     DEPOSITORY TRUST COMPANY TO COSTILLA ENERGY, INC. OR THE REGISTRAR FOR 
     REGISTRATION OF TRANSFER OR EXCHANGE AND ANY NOTE ISSUED IS REGISTERED 
     IN THE NAME OF CEDE & CO. OR SUCH OTHER ENTITY AS HAS BEEN REQUESTED BY
     AN AUTHORIZED REPRESENTATIVE OF THE DEPOSITORY TRUST COMPANY (AND ANY 
     PAYMENT HEREON IS MADE TO CEDE & CO. OR TO SUCH OTHER ENTITY AS HAS BEEN
     REQUESTED BY AN AUTHORIZED REPRESENTATIVE OF THE DEPOSITORY TRUST COMPANY),
     ANY TRANSFER, PLEDGE OR OTHER USE HEREOF FOR VALUE OR OTHERWISE BY OR TO 
     ANY PERSON IS WRONGFUL SINCE THE REGISTERED OWNER HEREOF, CEDE & CO., HAS
     AN INTEREST HEREIN.
   
     TRANSFER OF THIS GLOBAL NOTE SHALL BE LIMITED TO TRANSFERS IN WHOLE, AND 
     NOT IN PART, TO NOMINEES OF THE DEPOSITORY TRUST COMPANY OR TO A SUCCESSOR
     THEREOF OR SUCH SUCCESSOR'S NOMINEE AND TRANSFERS OF INTERESTS IN THIS 
     GLOBAL NOTE SHALL BE LIMITED TO TRANSFERS MADE IN ACCORDANCE WITH THE 
     RESTRICTIONS SET FORTH IN SECTION 2.06 OF THE INDENTURE, DATED AS OF
     ___________________, 1996, BETWEEN COSTILLA ENERGY, INC., AND THE TRUSTEE
     NAMED THEREIN, PURSUANT TO WHICH THIS NOTE WAS ISSUED.
    

<PAGE>

                                   GLOBAL NOTE                              
REPRESENTING ____% SENIOR SUBORDINATED NOTES DUE 2006

     Costilla Energy, Inc., a Delaware corporation, for value received, 
hereby promises to pay to CEDE & CO., or its registered assigns, the 
principal sum indicated on Schedule A hereof, on __________________, 2006.

     Reference is hereby made to the further provisions of this Note set 
forth on the reverse hereof, which further provisions shall for all purposes 
have the same effect as if set forth at this place.

     Unless the certificate of authentication hereon has been duly executed 
by the Trustee referred to on the reverse hereof by manual signature, this 
Note shall not be entitled to any benefit under the Indenture or be valid or 
obligatory for any purposes.
 
     IN WITNESS WHEREOF, the Company has caused this Note to be duly executed 
under its corporate seal.

                                         COSTILLA ENERGY, INC.

                                         By:                                  
                                            --------------------------------- 
                                         Name:  
                                         Title: 

[Corporate Seal]

Attest:

By:                                        
   --------------------------------- 
Name:  
Title: 

Dated:

TRUSTEE'S CERTIFICATE OF AUTHENTICATION

STATE STREET BANK AND TRUST COMPANY,
  as Trustee, certifies that this is one of
  the Notes referred to in the Indenture.

By:                                        
   ---------------------------------- 
         Authorized Signatory 


                                  A-2 
<PAGE>

                 FORM OF REVERSE SIDE OF GLOBAL NOTE

                         COSTILLA ENERGY, INC.
                              GLOBAL NOTE

         REPRESENTING ___% SENIOR SUBORDINATED NOTES DUE 2006

     1.  INDENTURE.
   
         This Note is one of a duly authorized issue of debt securities of 
the Company (as defined below) designated as its "____% Senior Subordinated 
Notes due 2006" (herein called the "Notes") limited in aggregate principal 
amount to $100,000,000, issued under an indenture dated as of _______________,
1996 (as amended or supplemented from time to time, the "Indenture") between 
the Company and State Street Bank and Trust Company, as trustee (the 
"Trustee," which term includes any successor Trustee under the Indenture), to 
which Indenture reference is hereby made for a statement of the respective 
rights, limitations of rights, duties and immunities thereunder of the 
Company, the subsidiaries of the Company that have guaranteed the payment of 
the Notes (the "Subsidiary Guarantors"), the Trustee and each Holder of Notes
and of the terms upon which the Notes are, and are to be, authenticated and 
delivered.  The summary of the terms of this Note contained herein does not 
purport to be complete and is qualified by reference to the Indenture.  All 
terms used in this Note which are not defined herein shall have the meanings 
assigned to them in the Indenture.
    

         The Indenture restricts, among other things, the Company's and its 
Subsidiaries' ability to incur additional indebtedness and issue preferred 
stock, incur liens to secure PARI PASSU or subordinated indebtedness, pay 
dividends or make certain other restricted payments, apply net proceeds from 
certain asset sales, enter into certain transactions with affiliates, incur 
indebtedness that is subordinate in right of payment to any Senior 
Indebtedness and senior in right of payment to the Notes, merge or 
consolidate with any other person, sell stock of Subsidiaries or sell, 
assign, transfer, lease, convey or otherwise dispose of substantially all of 
the assets of the Company.  The Indenture permits, under certain 
circumstances, Subsidiaries of the Company to be deemed Unrestricted 
Subsidiaries and thus not subject to the restrictions of the Indenture.

     2.  PRINCIPAL AND INTEREST.

         Costilla Energy, Inc., a Delaware corporation (such corporation, and 
its successors and assigns under the Indenture hereinafter referred to, being 
herein called the "Company"), promises to pay the principal amount set forth 
on Schedule A of this Note to the Holder hereof on ___________, 2006.

         The Company shall pay interest on this Note at a rate of ____%, per 
annum semiannually in arrears on ________________ __, and ________________ 
__, of each year, commencing on ____________ __, 1997, to the Holder hereof 
until the principal amount hereof is paid or duly provided for.  Interest 
shall accrue from __________________, 1996 or from the most 

                                  A-3 
<PAGE>

recent Interest Payment Date thereafter to which interest has been paid or 
duly provided for. The interest so payable, and punctually paid or duly 
provided for, on any Interest Payment Date will, subject to certain 
exceptions provided in the Indenture, be paid to the Person in whose name 
this Note (or the Note in exchange or substitution for which this Note was 
issued) is registered at the close of business on the Record Date for 
interest payable on such Interest Payment Date.  The Record Date for any 
interest payment is the close of business on ______________ __, or 
______________ __, as the case may be, whether or not a Business Day, 
immediately preceding the Interest Payment Date on which such interest is 
payable.  Any such interest not so punctually paid or duly provided for 
("Defaulted Interest") shall forthwith cease to be payable to the Holder on 
such Record Date and shall be paid as provided in Section 2.11 of the 
Indenture.  Interest will be computed on the basis of a 360-day year of 
twelve 30-day months.

         Each payment of interest in respect of an Interest Payment Date will 
include interest accrued through the day before such Interest Payment Date.  
If an Interest Payment Date falls on a day that is not a Business Day, the 
interest payment to be made on such Interest Payment Date will be made on the 
next succeeding Business Day with the same force and effect as if made on 
such Interest Payment Date, and no additional interest will accrue as a 
result of such delayed payment.

         To the extent lawful, the Company shall pay interest on overdue 
principal, overdue premium, and Defaulted Interest (without regard to any 
applicable grace period), at the interest rate borne on the Notes.  The 
Company's obligation pursuant to the previous sentence shall apply whether 
such overdue amount is due at its Stated Maturity, as a result of the 
Company's obligations pursuant to Section 3.05, Section 4.07 or Section 4.08 
of the Indenture, or otherwise.

     3.  METHOD OF PAYMENT.

         The Company, through the Paying Agent, shall pay interest on this 
Note to the registered Holder of this Note, as provided above.  The Holder 
must surrender this Note to a Paying Agent to collect principal payments.  
The Company will pay principal, premium, if any, and interest in money of the 
United States of America that at the time of payment is legal tender for 
payment of all debts public and private. Principal, premium, if any, and 
interest will be payable at the office of the Paying Agent but, at the option 
of the Company, interest may be paid by check mailed to the registered 
Holders at their registered addresses; PROVIDED that all payments with 
respect to Notes the Holders of which have given wire transfer instructions 
to the Company will be required to be made by wire transfer of immediately 
available funds to the accounts specified by the Holders thereof.

     4.  PAYING AGENT AND REGISTRAR.

         Initially, the Trustee will act as Paying Agent and Registrar under 
the Indenture.  The Company may, upon written notice to the Trustee, appoint 
and change any Paying Agent or Registrar.  The Company or any of its 
subsidiaries may act as Paying Agent or Registrar.

                                  A-4 
<PAGE>

     5.  OPTIONAL REDEMPTION.

         The Notes may not be redeemed at the Company's option prior to 
_____, 2001.  Thereafter, the Notes will be subject to redemption at the 
option of the Company, in whole or in part, upon not less than 30 calendar 
days' nor more than 60 calendar days' notice, at the redemption prices 
(expressed as percentages of principal amount) set forth below, plus accrued 
and unpaid interest thereon (if any) to the applicable Redemption Date, if 
redeemed during the twelve-month period beginning on _________ of the years 
indicated below:

              YEAR                                  PERCENTAGE 
              ----                                  ---------- 
              2001                                    _______%
              2002                                    _______%
              2003                                    _______%
              2004 and thereafter                     100.000%

         Notwithstanding the foregoing, at any time on or before 
_____________, 1999, the Company may (but shall not have the obligation to) 
redeem up to 30% of the original aggregate principal amount of the Notes at a 
redemption price of _______% of the principal amount thereof, plus accrued 
and unpaid interest thereon to the Redemption Date, with the net proceeds of 
an Equity Offering made by the Company; PROVIDED that at least 70% of the 
aggregate principal amount of Notes originally issued remain outstanding 
immediately after the occurrence of such redemption; and PROVIDED, FURTHER, 
that such redemption shall occur within 75 days of the date of the closing of 
such Equity Offering.

         The Notes are not subject to any sinking fund.

     6.  NOTICE OF REDEMPTION.

         At least 30 calendar days but not more than 60 calendar days before 
a Redemption Date, the Company will send a notice of redemption, first-class 
mail, postage prepaid, to Holders of Notes to be redeemed at the addresses of 
such Holders as they appear in the Security Register.

         If less than all of the Notes are to be redeemed at any time, the 
Notes to be redeemed will be chosen by the Trustee in accordance with the 
Indenture.  If any Note is redeemed subsequent to a Record Date with respect 
to any Interest Payment Date specified above and on or prior to such Interest 
Payment Date, then any accrued interest will be paid on such Interest Payment 
Date to the Holder of the Note at the close of business on such Record Date.  
If money in an amount sufficient to pay the Redemption Price of all Notes (or 
portions thereof) to be redeemed on the Redemption Date is deposited with the 
Paying Agent on or before the applicable Redemption Date and certain other 
conditions are satisfied, interest on the Notes or portions thereof to be 
redeemed on the applicable Redemption Date will cease to accrue.



                                  A-5 
<PAGE>

     7.  REPURCHASE AT THE OPTION OF HOLDERS UPON CHANGE OF CONTROL.

         Upon the occurrence of a Change of Control, each Holder of Notes 
shall have the right to require the Company to purchase such Holder's Notes, 
in whole or in part, in a principal amount that is an integral multiple of 
$1,000, pursuant to a Change of Control Offer, at a purchase price in cash 
equal to 101% of the aggregate principal amount thereof plus accrued and 
unpaid interest thereon to the Change of Control Payment Date.

         Within 30 calendar days following any Change of Control, the Company 
shall send, or cause to be sent, by first-class mail, postage prepaid, a 
notice regarding the Change of Control Offer to each Holder of Notes.  The 
Holder of this Note may elect to have this Note or a portion hereof in an 
authorized denomination purchased by completing the form entitled "Option of 
Holder to Elect Purchase" appearing below and tendering this Note pursuant to 
the Change of Control Offer.  Unless the Company defaults in the payment of 
the Change of Control Purchase Price with respect thereto, all Notes or 
portions thereof accepted for payment pursuant to the Change of Control Offer 
will cease to accrue interest from and after the Change of Control Payment 
Date.

     8.  REPURCHASE AT THE OPTION OF HOLDERS UPON ASSET SALE.

         If at any time the Company or any Subsidiary engages in any Asset 
Sale, the Company shall, within 30 calendar days of the date the amount of 
Excess Proceeds exceeds $5.0 million, use the then-existing Excess Proceeds 
to make an offer to purchase from all Holders, on a pro rata basis, Notes in 
an aggregate principal amount equal to the maximum principal amount that may 
be purchased out of the then-existing Excess Proceeds, at a purchase price in 
cash in an amount equal to 100% of the principal amount thereof plus accrued 
and unpaid interest thereon, if any, to the Asset Sale Payment Date.  Upon 
completion of an Asset Sale Offer (including payment of the Asset Sale 
Purchase Price for accepted Notes), any surplus Excess Proceeds that were the 
subject of such offer shall cease to be Excess Proceeds, and the Company may 
then use such amounts for general corporate purposes.

         Within 30 calendar days of the date the amount of Excess Proceeds 
exceeds $5.0 million, the Company shall send, or cause to be sent, by 
first-class mail, postage prepaid, a notice regarding the Asset Sale Offer to 
each Holder of Notes.  The Holder of this Note may elect to have this Note or 
a portion hereof in an authorized denomination purchased by completing the 
form entitled "Option of Holder to Elect Purchase" appearing below and 
tendering this Note pursuant to the Asset Sale Offer.  Unless the Company 
defaults in the payment of the Asset Sale Purchase Price with respect 
thereto, all Notes or portions thereof selected for payment pursuant to the 
Asset Sale Offer will cease to accrue interest from and after the Asset Sale 
Payment Date.

     9.  THE GLOBAL NOTE.

         So long as this Global Note is registered in the name of the 
Depositary or its nominee, members of, or participants in, the Depositary 
("Agent Members") shall have no rights under the 

                                  A-6 
<PAGE>

Indenture with respect to this Global Note held on their behalf by the 
Depositary or the Trustee as its custodian, and the Depositary may be treated 
by the Company, the Trustee and any agent of the Company or the Trustee as 
the absolute owner of this Global Note for all purposes.  Notwithstanding the 
foregoing, nothing herein shall (i) prevent the Company, the Trustee or any 
agent of the Company or the Trustee, from giving effect to any written 
certification, proxy or other authorization furnished by the Depositary or 
(ii) impair, as between the Depositary and its Agent Members, the operation 
of customary practices governing the exercise of the rights of a Holder of 
Notes.

         The Holder of this Global Note may grant proxies and otherwise 
authorize any Person, including Agent Members and Persons that may hold 
interests in this Global Note through Agent Members, to take any action which 
a Holder of Notes is entitled to take under the Indenture or the Notes.

         Whenever, as a result of optional redemption by the Company, a 
Change of Control Offer, an Asset Sale Offer or an exchange for Certificated 
Notes, this Global Note is redeemed, repurchased or exchanged in part, this 
Global Note shall be surrendered by the Holder thereof to the Trustee who 
shall cause an adjustment to be made to Schedule A hereof so that the 
principal amount of this Global Note will be equal to the portion not 
redeemed, repurchased or exchanged and shall thereafter return this Global 
Note to such Holder; PROVIDED that this Global Note shall be in a principal 
amount of $1,000 or an integral multiple of $1,000.

     10. TRANSFER AND EXCHANGE.

         The Holder of this Global Note shall, by acceptance of this Global 
Note, agree that transfers of beneficial interests in this Global Note may be 
effected only through a book entry system maintained by such Holder (or its 
agent), and that ownership of a beneficial interest in the Notes represented 
thereby shall be required to be reflected in book entry form.

         Transfers of this Global Note shall be limited to transfers in whole 
and not in part, to the Depositary, its successors, and their respective 
nominees.  Interests of beneficial owners in this Global Note shall be 
transferred in accordance with the rules and procedures of the Depositary (or 
its successors).

         This Global Note shall be exchanged by the Company for one or more 
Certificated Notes if (a) the Depositary (i) has notified the Company that it 
is unwilling or unable to continue as, or ceases to be, a clearing agency 
registered under Section 17A of the Exchange Act and (ii) a successor to the 
Depositary registered as a clearing agency under Section 17A of the Exchange 
Act is not able to be appointed by the Company within 90 calendar days or (b) 
the Depositary is at any time unwilling or unable to continue as Depositary 
and a successor to the Depositary is not able to be appointed by the Company 
within 90 calendar days.  If an Event of Default occurs and is continuing, 
the Company shall, at the request of the Holder hereof, exchange all or part 
of this Global Note for one or more Certificated Notes; PROVIDED that the 
principal amount of each of such Certificated Notes and this Global Note, 
after such exchange, shall be $1,000 or an integral multiple 

                                  A-7 
<PAGE>

thereof.  Whenever this Global Note is exchanged as a whole for one or more 
Certificated Notes, it shall be surrendered by the Holder to the Trustee for 
cancellation.  Whenever this Global Note is exchanged in part for one or more 
Certificated Notes, it shall be surrendered by the Holder to the Trustee and 
the Trustee shall make the appropriate notations hereon pursuant to Section 
2.05(c) of the Indenture.  All Certificated Notes issued in exchange for this 
Global Note or any portion hereof shall be registered in such names, and 
delivered, as the Depositary shall instruct the Trustee.

         The Holder of this Note shall have the right to obtain from the 
Company the information specified in Section 4.17 of the Indenture.

     11. DENOMINATIONS.

         The Notes are issuable only in registered form without coupons in 
denominations of $1,000 and integral multiples thereof of principal amount.

     12. UNCLAIMED MONEY.

         If money for the payment of principal, premium, if any, or interest 
remains unclaimed for two years, the Trustee or Paying Agent shall pay the 
money back to the Company at its request unless an abandoned property law 
designates another Person. After any such payment, Holders entitled to the 
money must look only to the Company and not to the Trustee for payment unless 
such abandoned property law designates another Person.

     13. DISCHARGE AND DEFEASANCE.

         Subject to certain conditions, the Company at any time may terminate 
some or all of its obligations under the Notes and the Indenture if the 
Company irrevocably deposits with the Trustee money or U.S. Government 
Obligations for the payment of principal, premium, if any, and interest on 
the Notes to redemption or maturity, as the case may be.

     14. AMENDMENT, WAIVER.
   
         Subject to certain exceptions set forth in the Indenture, (i) the 
Indenture, the Subsidiary Guarantees or the Notes may be amended with the 
written consent of the Holders of at least a majority in principal amount of 
the outstanding Notes and (ii) any past Default and its consequences may be 
waived with the written consent of the Holders of at least a majority in 
principal amount of the outstanding Notes. Subject to certain exceptions set 
forth in the Indenture and the Subsidiary Guarantees, without the consent of 
any Holder of Notes, the Company, the Subsidiary Guarantors and the Trustee 
may amend the Indenture, the Subsidiary Guarantees or the Notes (i) to 
evidence the succession of another Person to (A) the Company and the 
assumption by such successor of the covenants of the Company under the 
Indenture and contained in the Notes or (B) a Subsidiary Guarantor and the 
assumption by such successor of the covenants of such Subsidiary Guarantor 
contained in its Subsidiary Guarantee; (ii) to add additional covenants or to 
surrender rights and powers conferred on the Company or any Subsidiary; (iii) 
to add any 
    

                                  A-8 
<PAGE>

   
additional Events of Default; (iv) to provide for uncertificated Notes in 
addition to or in place of Certificated Notes; (v) to evidence and provide 
for the acceptance of appointment under the Indenture of a successor Trustee; 
(vi) to secure the Notes; (vii) to cure any ambiguity in the Indenture or the 
Subsidiary Guarantees, to correct or supplement any provision in the 
Indenture or the Subsidiary Guarantees which may be inconsistent with any 
other provision therein or to add any other provisions with respect to 
matters or questions arising under the Indenture, PROVIDED that such actions 
shall not adversely affect the interests of the Holders in any material 
respect; (viii) to comply with the requirements of the Commission in order to 
effect or maintain the qualification of the Indenture under the Trust 
Indenture Act; or (ix) to release any Subsidiary Guarantor pursuant to the 
Indenture. 
    

     15. DEFAULTS AND REMEDIES.

         If an Event of Default occurs and is continuing, the Trustee or the 
Holders of at least 25% in principal amount of the Notes, subject to certain 
limitations, may declare all the Notes to be immediately due and payable.  
Certain events of bankruptcy or insolvency are Events of Default and shall 
result in the Notes being-immediately due and payable upon the occurrence of 
such Events of Default without any further act of the Trustee or any Holder.

         Holders of Notes may not enforce the Indenture or the Notes except 
as provided in the Indenture.  The Trustee may refuse to enforce the 
Indenture or the Notes unless it receives reasonable indemnity or security.  
Subject to certain limitations, Holders of a majority in principal amount of 
the Notes may direct the Trustee in its exercise of any trust or power under 
the Indenture.  The Holders of a majority in principal amount of the then 
outstanding Notes, by written notice to the Trustee, may rescind any 
declaration of acceleration and its consequences if the rescission would not 
conflict with any judgment or decree, and if all Events of Default have been 
cured or waived except nonpayment of principal, interest or premium that has 
become due solely because of the acceleration.

     16. SUBORDINATION.
   
         The payment of principal of, premium, if any, and interest on the 
Notes will be subordinated in right of payment to the prior payment in full 
of Senior Indebtedness as set forth in Article X of the Indenture.  The 
obligations of the Subsidiary Guarantors to the Holders or the Trustee 
pursuant to the Subsidiary Guarantees and the Indenture will be subordinated 
in right of payment to the prior payment in full of Guarantor Senior 
Indebtedness as set forth in Article XI of the Indenture and the Subsidiary 
Guarantees.

     17. SUBSIDIARY GUARANTEE.  

         Subject to the limitations set forth in the Indenture and the 
Subsidiary Guarantees, the payment of principal of, premium, if any, and 
interest on the Notes will be guaranteed by each Subsidiary Guarantor. 
    

                                  A-9 
<PAGE>

     18. INDIVIDUAL RIGHTS OF TRUSTEE.

         Subject to certain limitations imposed by the Trust Indenture Act, 
the Trustee or any Paying Agent or Registrar, in its individual or any other 
capacity, may become the owner or pledgee of Notes and may otherwise deal 
with the Company or its Affiliates with the same rights it would have if it 
were not Trustee, Paying Agent or Registrar, as the case may be, under the 
Indenture.

     19. NO RECOURSE AGAINST CERTAIN OTHERS.
   
         No director, officer, employee, incorporator or stockholder of the 
Company or any Subsidiary Guarantor, as such, shall have any liability for 
any obligations of the Company or such Subsidiary Guarantor under the Notes, 
the Subsidiary Guarantees or the Indenture or for any claim based on, in 
respect of, or by reason of, such obligations or their creation, solely by 
reason of its status as a director, officer, employee, incorporator or 
stockholder of the Company or any Subsidiary Guarantor.  By accepting a Note, 
each Holder waives and releases all such liability (but only such liability) 
as part of the consideration for issuance of such Note to such Holder.
    

     20. GOVERNING LAW.

         THE INDENTURE AND THIS NOTE SHALL BE GOVERNED BY, AND CONSTRUED IN 
ACCORDANCE WITH, THE LAWS OF THE STATE OF NEW YORK APPLICABLE TO AGREEMENTS 
MADE AND TO BE PERFORMED IN SAID STATE.

         The Company will furnish to any Holder of Notes upon written request 
and without charge to the Holder a copy of the Indenture which has in it the 
text of this Note.  Requests may be made to:

                                      Costilla Energy, Inc.
                                      400 West Illinois, 10th Floor
                                      Midland, Texas  79701
                                      Attention:  Chief Financial Officer





                                  A-10 
<PAGE>

                               SCHEDULE A

                       SCHEDULE OF PRINCIPAL AMOUNT

The initial principal amount at maturity of this Note shall be $100,000,000.  
The following decreases/increase in the principal amount at maturity of this 
Note have been made:

                                             TOTAL PRINCIPAL 
                                             AMOUNT AT       
                DECREASE IN   INCREASE IN    MATURITY        
DATE OF         PRINCIPAL     PRINCIPAL      FOLLOWING SUCH    NOTATION MADE   
DECREASE/       AMOUNT AT     AMOUNT AT      DECREASE/         BY OR ON BEHALF 
INCREASE        MATURITY      MATURITY       INCREASE          OF TRUSTEE      
- ---------       -----------   -----------    ---------------   --------------- 

_____________   ___________   ___________    _______________   _______________ 

_____________   ___________   ___________    _______________   _______________ 

_____________   ___________   ___________    _______________   _______________ 

_____________   ___________   ___________    _______________   _______________ 

_____________   ___________   ___________    _______________   _______________ 

_____________   ___________   ___________    _______________   _______________ 

_____________   ___________   ___________    _______________   _______________ 

_____________   ___________   ___________    _______________   _______________ 

_____________   ___________   ___________    _______________   _______________ 

_____________   ___________   ___________    _______________   _______________ 

_____________   ___________   ___________    _______________   _______________ 

_____________   ___________   ___________    _______________   _______________ 

_____________   ___________   ___________    _______________   _______________ 

_____________   ___________   ___________    _______________   _______________ 


                                  A-11 
<PAGE>

                               ASSIGNMENT

               (To be executed by the registered Holder
            if such Holder desires to transfer this Note)

FOR VALUE RECEIVED __________________ hereby sells, assigns and transfers unto

PLEASE INSERT SOCIAL SECURITY OR OTHER
TAX IDENTIFYING NUMBER OF TRANSFEREE

_______________________________

_____________________________________________________________________________ 

              (Please print name and address of transferee) 
 
this Note, together with all right, title and interest herein, and does 
hereby irrevocably constitute and appoint ______________________________ 
Attorney to transfer this Note on the Security Register, with full power of 
substitution.

Dated:________________________ 


_______________________________        ______________________________________ 
Signature of Holder                    Signature Guaranteed by an 
                                       institution member of the
                                       Signature Guaranty Medallion
                                       Program


NOTICE:  The signature to the foregoing Assignment must correspond to the 
Name as written upon the face of this Note in every particular, without 
alteration or any change whatsoever.





                                  A-12 
<PAGE>

                     OPTION OF HOLDER TO ELECT PURCHASE
                           (check as appropriate)

/ /  In connection with the Change of Control Offer made pursuant to Section 
     4.07 of the Indenture, the undersigned hereby elects to have

     / /  the entire principal amount

     / /  $_________________ ($1,000 in principal amount or an integral multiple
           thereof) of this Note 

          repurchased by the Company.  The undersigned hereby directs the 
          Trustee or Paying Agent to pay it or ____________________ an amount
          in cash equal to 101% of the principal amount indicated in the 
          preceding sentence, plus accrued and unpaid interest thereon, if any,
          to the Change of Control Payment Date.

/ /  In connection with the Asset Sale Offer made pursuant to Section 4.08 of
     the Indenture, the undersigned hereby elects to have

     / /  the entire principal amount

     / /  $_________________ ($1,000 in principal amount or an integral multiple
          thereof) of this Note

          repurchased by the Company.  The undersigned hereby directs the 
          Trustee or Paying Agent to pay it or ____________________ an amount
          in cash equal to 100% of the principal amount indicated in the 
          preceding sentence, plus accrued and unpaid interest thereon, if any,
          to the Asset Sale Payment Date.

Dated:________________________ 


_______________________________        ______________________________________ 
Signature of Holder                    Signature Guaranteed by an institution
                                       member of the Signature Guaranty 
                                       Medallion Program 



NOTICE:  The signature to the foregoing must correspond to the Name as 
written upon the face of this Note in every particular, without alteration or 
any change whatsoever. 


                                     A-13 
<PAGE>

                                                                   EXHIBIT B

                      FORM OF FACE OF CERTIFICATED NOTE

                             COSTILLA ENERGY, INC.

No._________                                            CUSIP No. ___________



                    ___% SENIOR SUBORDINATED NOTE DUE 2006

     Costilla Energy, Inc., a Delaware corporation, for value received, hereby 
promises to pay to _________________ or its registered assigns, the principal 
amount of _____________ on ____________, 2006.

     Reference is hereby made to the further provisions of this Note set forth
on the reverse hereof, which further provisions shall for all purposes have the
same effect as if set forth at this place.

     Unless the certificate of authentication hereon has been duly executed 
by the Trustee referred to on the reverse hereof by manual signature, this 
Note shall not be entitled to any benefit under the Indenture or be valid or 
obligatory for any purposes.


<PAGE>

     IN WITNESS WHEREOF, the Company has caused this Note to be duly executed 
under its corporate seal.

                                       COSTILLA ENERGY, INC.

                                       By:
                                           ----------------------------------
                                       Name:
                                       Title:


[Corporate Seal]

Attest:

By: 
   ---------------------------
Name:
Title:

Dated:

TRUSTEE'S CERTIFICATE OF AUTHENTICATION

STATE STREET BANK AND TRUST COMPANY,
    as Trustee, certifies that this is one of
    the Notes referred to in the Indenture.


By: 
   ---------------------------
       Authorized Signatory






                                    B-2


<PAGE>

                   FORM OF REVERSE SIDE OF CERTIFICATED NOTE

                              COSTILLA ENERGY, INC.

                  ____% SENIOR SUBORDINATED NOTE DUE 2006

     1.   INDENTURE.
   

          This Note is one of a duly authorized issue of debt securities of 
the Company (as defined below) designated as its "____% Senior Subordinated 
Notes due 2006" (herein called the "Notes") limited in aggregate principal 
amount to $100,000,000, issued under an indenture dated as of 
________________, 1996 (as amended or supplemented from time to time, the 
"Indenture") between the Company and State Street Bank and Trust Company, as 
trustee (the "Trustee," which term includes any successor Trustee under the 
Indenture), to which Indenture reference is hereby made for a statement of 
the respective rights, limitations of rights, duties and immunities 
thereunder of the Company, the subsidiaries of the Company that have 
guaranteed the payment of the Notes (the "Subsidiary Guarantors"), the 
Trustee and each Holder of Notes and of the terms upon which the Notes are, 
and are to be, authenticated and delivered.  The summary of the terms of this 
Note contained herein does not purport to be complete and is qualified by 
reference to the Indenture.  All terms used in this Note which are not 
defined herein shall have the meanings assigned to them in the Indenture. 
    

          The Indenture restricts, among other things, the Company's and its 
Subsidiaries' ability to incur additional indebtedness and issue preferred 
stock, incur liens to secure PARI PASSU or subordinated indebtedness, pay 
dividends or make certain other restricted payments, apply net proceeds from 
certain asset sales, enter into certain transactions with affiliates, incur 
indebtedness that is subordinate in right of payment to any Senior Indebtedness
and senior in right of payment to the Notes, merge or consolidate with any 
other person, sell stock of Subsidiaries or sell, assign, transfer, lease, 
convey or otherwise dispose of substantially all of the assets of the Company.
The Indenture permits, under certain circumstances, Subsidiaries of the Company
to be deemed Unrestricted Subsidiaries and thus not subject to the restrictions
of the Indenture.

     2.   PRINCIPAL AND INTEREST.

          Costilla Energy, Inc., a Delaware corporation (such corporation, and
its successors and assigns under the Indenture hereinafter referred to, being 
herein called the "Company"), promises to pay the principal amount set forth on
the face hereof to the Holder hereof on __________________, 2006.

          The Company shall pay interest on this Note at a rate of ____%, per 
annum semiannually in arrears on _______________ __, and _____________ __ of 
each year, commencing on ____________ __, 1997, to the Holder hereof until 
the principal amount hereof is paid or duly provided for.  Interest shall 
accrue from _________________, 1996 or from the most recent Interest Payment 
Date thereafter to which interest has been paid or duly provided for.  The 
interest so 




                                    B-3


<PAGE>

payable, and punctually paid or duly provided for, on any Interest Payment 
Date will, subject to certain exceptions provided in the Indenture, be paid 
to the Person in whose name this Note (or the Note in exchange or substitution
for which this Note was issued) is registered at the close of business on the 
Record Date for interest payable on such Interest Payment Date.  The Record 
Date for any interest payment is the close of business on _________ __, or 
__________ __, as the case may be, whether or not a Business Day, immediately 
preceding the Interest Payment Date on which such interest is payable.  Any 
such interest not so punctually paid or duly provided for ("Defaulted Interest")
shall forthwith cease to be payable to the Holder on such Record Date and shall
be paid as provided in Section 2.11 of the Indenture.  Interest will be computed
on the basis of a 360-day year of twelve 30-day months.

          Each payment of interest in respect of an Interest Payment Date 
will include interest accrued through the day before such Interest Payment 
Date.  If an Interest Payment Date falls on a day that is not a Business Day, 
the interest payment to be made on such Interest Payment Date will be made on 
the next succeeding Business Day with the same force and effect as if made on 
such Interest Payment Date, and no additional interest will accrue as a 
result of such delayed payment.

          To the extent lawful, the Company shall pay interest on overdue 
principal, overdue premium, and Defaulted Interest (without regard to any 
applicable grace period), at the interest rate borne on the Notes.  The 
Company's obligation pursuant to the previous sentence shall apply whether 
such -overdue amount is due at its Stated Maturity, as a result of the 
Company's obligations pursuant to Section 3.05, Section 4.07 or Section 4.08 
of the Indenture, or otherwise.

     3.   METHOD OF PAYMENT.

          The Company, through the Paying Agent, shall pay interest on this 
Note to the registered Holder of this Note, as provided above.  The Holder 
must surrender this Note to a Paying Agent to collect principal payments.  The
Company will pay principal, premium, if any, and interest in money of the United
States of America that at the time of payment is legal tender for payment of all
debts public and private. Principal, premium, if any, and interest will be 
payable at the office of the Paying Agent but, at the option of the Company,
interest may be paid by check mailed to the registered Holders at their 
registered addresses; provided that all payments with respect to Notes the 
Holders of which have given wire transfer instructions to the Company will be
required to be made by wire transfer of immediately available funds to the 
accounts specified by the Holders thereof.

     4.   PAYING AGENT AND REGISTRAR.

          Initially, the Trustee will act as Paying Agent and Registrar under 
the Indenture.  The Company may, upon written notice to the Trustee, appoint and
change any Paying Agent or Registrar.  The Company or any of its subsidiaries 
may act as Paying Agent or Registrar.




                                    B-4


<PAGE>

     5.   OPTIONAL REDEMPTION.

          The Notes may not be redeemed at the Company's option prior to 
2001.  Thereafter, the Notes will be subject to redemption at the option of 
the Company, in whole or in part, upon not less than 30 calendar days' nor 
more than 60 calendar days' notice, at the redemption prices (expressed as 
percentages of principal amount) set forth below, plus accrued and unpaid 
interest thereon (if any) to the applicable Redemption Date, if redeemed 
during the twelve-month period beginning on ______________ of the years 
indicated below:

               Year                                Percentage
               2001                                 _______%
               2002                                 _______%
               2003                                 _______%
               2004 and thereafter                  100.000%

          Notwithstanding the foregoing, at any time on or before _____________,
1999, the Company may (but shall not have the obligation to) redeem up to 30% 
of the original aggregate principal amount of the Notes at a redemption price 
of _____% of the principal amount thereof, plus accrued and unpaid interest 
thereon to the Redemption Date, with the net proceeds of an Equity Offering 
made by the Company; provided that at least 70% of the aggregate principal 
amount of Notes originally issued remain outstanding immediately after the 
occurrence of such redemption; and provided, further, that such redemption 
shall occur within 75 days of the date of the closing of such Equity Offering.

     The Notes are not subject to any sinking fund.

     6.   NOTICE OF REDEMPTION.

          At least 30 calendar days but not more than 60 calendar days before 
a Redemption Date, the Company will send a notice of redemption, first-class 
mail, postage prepaid, to Holders of Notes to be redeemed at the addresses of 
such Holders as they appear in the Security Register.

          If less than all of the Notes are to be redeemed at any time, the 
Notes to be redeemed will be chosen by the Trustee in accordance with the 
Indenture.  If any Note is redeemed subsequent to a Record Date with respect 
to any Interest Payment Date specified above and on or prior to such Interest 
Payment Date, then any accrued interest will be paid on such Interest Payment 
Date to the Holder of the Note at the close of business on such Record Date.  
If money in an amount sufficient to pay the Redemption Price of all Notes (or 
portions thereof) to be redeemed on the Redemption Date is deposited with the 
Paying Agent on or before the applicable Redemption Date and certain other 
conditions are satisfied, interest on the Notes or portions thereof to be 
redeemed on the applicable Redemption Date will cease to accrue.





                                    B-5


<PAGE>

     7.   REPURCHASE AT THE OPTION OF HOLDERS UPON CHANGE OF CONTROL.

          Upon the occurrence of a Change of Control, each Holder of Notes 
shall have the right to require the Company to purchase such Holder's Notes, 
in whole or in part, in a principal amount that is an integral multiple of 
$1,000, pursuant to a Change of Control Offer, at a purchase price in cash 
equal to 101% of the aggregate principal amount thereof plus accrued and 
unpaid interest thereon to the Change of Control Payment Date.

          Within 30 calendar days following any Change of Control, the 
Company shall send, or cause to be sent, by first-class mail, postage 
prepaid, a notice regarding the Change of Control Offer to each Holder of 
Notes.  The Holder of this Note may elect to have this Note or a portion 
hereof in an authorized denomination purchased by completing the form 
entitled "Option of Holder to Elect Purchase" appearing below and tendering 
this Note pursuant to the Change of Control Offer.  Unless the Company 
defaults in the payment of the Change of Control Purchase Price with respect 
thereto, all Notes or portions thereof accepted for payment pursuant to the 
Change of Control Offer will cease to accrue interest from and after the 
Change of Control Payment Date.

     8.   REPURCHASE AT THE OPTION OF HOLDERS UPON ASSET SALE.

          If at any time the Company or any Subsidiary engages in any Asset 
Sale, the Company shall, within 30 calendar days of the date the amount of 
Excess Proceeds exceeds $5.0 million, use the then-existing Excess Proceeds 
to make an offer to purchase from all Holders, on a pro rata basis, Notes in 
an aggregate principal amount equal to the maximum principal amount that may 
be purchased out of the then-existing Excess Proceeds, at a purchase price in 
cash in an amount equal to 100% of the principal amount thereof plus accrued 
and unpaid interest thereon, if any, to the Asset Sale Payment Date.  Upon 
completion of an Asset Sale Offer (including payment of the Asset Sale 
Purchase Price for accepted Notes), any surplus Excess Proceeds that were the 
subject of such offer shall cease to be Excess Proceeds, and the Company may 
then use such amounts for general corporate purposes.

          Within 30 calendar days of the date the amount of Excess Proceeds 
exceeds $5.0 million, the Company shall send, or cause to be sent, by 
first-class mail, postage prepaid, a notice regarding the Asset Sale Offer to 
each Holder of Notes.  The Holder of this Note may elect to have this Note or 
a portion hereof in an authorized denomination purchased by completing the 
form entitled "Option of Holder to Elect Purchase" appearing below and 
tendering this Note pursuant to the Asset Sale Offer.  Unless the Company 
defaults in the payment of the Asset Sale Purchase Price with respect 
thereto, all Notes or portions thereof selected for payment pursuant to the 
Asset Sale Offer will cease to accrue interest from and after the Asset Sale 
Payment Date.

     9.   TRANSFER AND EXCHANGE.

          A Holder may transfer a Note only upon the surrender of such Note 
for registration of transfer.  No such transfer shall be effected until, and 
such transferee shall succeed to the rights 



                                    B-6


<PAGE>

of a Holder only upon, final acceptance and registration of the transfer in 
the Security Register by the Registrar.  When Notes are presented to the 
Registrar with a request to register the transfer of, or to exchange, such 
Notes, the Registrar shall register the transfer or make such exchange as 
requested if its requirements for such transactions and any applicable 
requirements hereunder are satisfied.

          No service charge shall be made for any registration of transfer or 
exchange of Notes, but the Company may require payment of a sum sufficient to 
cover any tax or other governmental charge that may be imposed in connection 
with any registration of transfer of Notes.  

          The Holder of this Note shall have the right to obtain from the 
Company the information specified in Section 4.17 of the Indenture.

     10.  DENOMINATIONS.

          The Notes are issuable only in registered form without coupons in 
denominations of $1,000 and integral multiples thereof of principal amount.

     11.  UNCLAIMED MONEY.

          If money for the payment of principal, premium, if any, or interest 
remains unclaimed for two years, the Trustee or Paying Agent shall pay the 
money back to the Company at its request unless an abandoned property law 
designates another Person.  After any such payment, Holders entitled to the 
money must look only to the Company and not to the Trustee for payment unless 
such abandoned property law designates another Person.

     12.  DISCHARGE AND DEFEASANCE.

          Subject to certain conditions, the Company at any time may 
terminate some or all of its obligations under the Notes and the Indenture if 
the Company irrevocably deposits with the Trustee money or U.S. Government 
Obligations for the payment of principal, premium, if any, and interest on 
the Notes to redemption or maturity, as the case may be.

     13.  AMENDMENT, WAIVER.
   
          Subject to certain exceptions set forth in the Indenture, (i) the 
Indenture, the Subsidiary Guarantees or the Notes may be amended with the 
written consent of the Holders of at least a majority in principal amount of 
the outstanding Notes and (ii) any past Default and its consequences may be 
waived with the written consent of the Holders of at least a majority in 
principal amount of the outstanding Notes.  Subject to certain exceptions set 
forth in the Indenture and the Subsidiary Guarantees, without the consent of 
any Holder of Notes, the Company, the Subsidiary Guarantors and the Trustee 
may amend the Indenture, the Subsidiary Guarantees or the Notes (i) to 
evidence the succession of another Person to (A) the Company and the 
assumption by such successor of the covenants of the Company under the 
Indenture and contained in the Notes or (B) a Subsidiary Guarantor and the 
assumption by such successor of the covenants of such Subsidiary Guarantor 
under 
    

                                    B-7


<PAGE>

   
contained in its Subsidiary Guarantee; (ii) to add additional covenants or to 
surrender rights and powers conferred on the Company or any Subsidiary; (iii) 
to add any additional Events of Default; (iv) to provide for uncertificated 
Notes in addition to or in place of Certificated Notes; (v) to evidence and 
provide for the acceptance of appointment under the Indenture of a successor 
Trustee; (vi) to secure the Notes; (vii) to cure any ambiguity in the 
Indenture or the Subsidiary Guarantees, to correct or supplement any 
provision in the Indenture or the Subsidiary Guarantees which may be 
inconsistent with any other provision therein or to add any other provisions 
with respect to matters or questions arising under the Indenture, PROVIDED 
that such actions shall not adversely affect the interests of the Holders in 
any material respect; (viii) to comply with the requirements of the 
Commission in order to effect or maintain the qualification of the Indenture 
under the Trust Indenture Act; or (ix) to release any Subsidiary Guarantor 
pursuant to the Indenture. 
    

     14.  DEFAULTS AND REMEDIES.

          If an Event of Default occurs and is continuing, the Trustee or the 
Holders of at least 25% in principal amount of the Notes, subject to certain 
limitations, may declare all the Notes to be immediately due and payable.  
Certain events of bankruptcy or insolvency are Events of Default and shall 
result in the Notes being immediately due and payable upon the occurrence of 
such Events of Default without any further act of the Trustee or any Holder.

          Holders of Notes may not enforce the Indenture or the Notes except 
as provided in the Indenture.  The Trustee may refuse to enforce the 
Indenture or the Notes unless it receives reasonable indemnity or security.  
Subject to certain limitations, Holders of a majority in principal amount of 
the Notes may direct the Trustee in its exercise of any trust or power under 
the Indenture.  The Holders of a majority in principal amount of the then 
outstanding Notes, by written notice to the Trustee, may rescind any 
declaration of acceleration and its consequences if the rescission would not 
conflict with any judgment or decree, and if all Events of Default have been 
cured or waived except nonpayment of principal, interest or premium that has 
become due solely because of the acceleration.

     15.  SUBORDINATION.
   
          The payment of principal of, premium, if any, and interest on the 
Notes will be subordinated in right of payment to the prior payment in full 
of Senior Indebtedness as set forth in Article X of the Indenture.  The 
obligations of the Subsidiary Guarantors to the Holders or the Trustee 
pursuant to the Subsidiary Guarantees and the Indenture will be subordinated 
in right of payment to the prior payment in full of Guarantor Senior 
Indebtedness as set forth in Article XI of the Indenture and the Subsidiary 
Guarantees.

     16.  SUBSIDIARY GUARANTEE.

          Subject to the limitations set forth in the Indenture and the 
Subsidiary Guarantees, the payment of principal of, premium, if any, and 
interest on the Notes will be guaranteed by each Subsidiary Guarantor and all 
additional Subsidiary Guarantors. 
    

                                    B-8


<PAGE>

     17.  INDIVIDUAL RIGHTS OF TRUSTEE.

          Subject to certain limitations imposed by the Trust Indenture Act, 
the Trustee or any Paying Agent or Registrar, in its individual or any other 
capacity, may become the owner or pledgee of Notes and may otherwise deal 
with the Company or its Affiliates with the same rights it would have if it 
were not Trustee, Paying Agent or Registrar, as the case may be, under the 
Indenture.

     18.  NO RECOURSE AGAINST CERTAIN OTHERS.
   
          No director, officer, employee, incorporator or stockholder of the 
Company or any Subsidiary Guarantor, as such, shall have any liability for 
any obligations of the Company or such Subsidiary Guarantor under the Notes, 
the Subsidiary Guarantees or the Indenture or for any claim based on, in 
respect of, or by reason of, such obligations or their creation, solely by 
reason of its status as a director, officer, employee, incorporator or 
stockholder of the Company or any Subsidiary Guarantor.  By accepting a Note, 
each Holder waives and releases all such liability (but only such liability) 
as part of the consideration for issuance of such Note to such Holder.
    

     19.  GOVERNING LAW.

          THE INDENTURE AND THIS NOTE SHALL BE GOVERNED BY, AND CONSTRUED IN 
ACCORDANCE WITH, THE LAWS OF THE STATE OF NEW YORK APPLICABLE TO AGREEMENTS 
MADE AND TO BE PERFORMED IN SAID STATE.

          The Company will furnish to any Holder of Notes upon written request
and without charge to the Holder a copy of the Indenture which has in it the 
text of this Note.  Requests may be made to:


                                       Costilla Energy, Inc.
                                       400 West Illinois, 10th Floor
                                       Midland, Texas  79701
                                       Attention: Chief Financial Officer




                                    B-9


<PAGE>

                                  ASSIGNMENT

                   (To be executed by the registered Holder
                if such Holder desires to transfer this Note)

FOR VALUE RECEIVED __________________________ hereby sells, assigns and 
transfers unto

PLEASE INSERT SOCIAL SECURITY OR OTHER
TAX IDENTIFYING NUMBER OF TRANSFEREE

- -------------------------
                         |
- -----------------------------------------------------------------------------
                   (Please print name and address of transferee) 

- -----------------------------------------------------------------------------
this Note, together with all right, title and interest herein, and does hereby
irrevocably constitute and appoint ______________________________ Attorney to
transfer this Note on the Security Register, with full power of substitution.

Dated: 
       ------------------------

- ---------------------------------      ----------------------------------------
Signature of Holder                    Signature Guaranteed by an institution
                                       member of the Signature Guaranty 
                                       Medallion Program


NOTICE:  The signature to the foregoing Assignment must correspond to the Name 
as written upon the face of this Note in every particular, without alteration
or any change whatsoever. 





                                   B-10


<PAGE>

                      OPTION OF HOLDER TO ELECT PURCHASE
                             (check as appropriate)

/ /       In connection with the Change of Control Offer made pursuant to 
          Section 4.07 of the Indenture, the undersigned hereby elects to have

          / /     the entire principal amount

          / /     $_________________ ($1,000 in principal amount or an integral
                  multiple thereof) of this Note

          repurchased by the Company.  The undersigned hereby directs the 
          Trustee or Paying Agent to pay it or ____________________ an amount
          in cash equal to 101% of the principal amount indicated in the
          preceding sentence, plus accrued and unpaid interest thereon, if any,
          to the Change of Control Payment Date.

/ /       In connection with the Asset Sale Offer made pursuant to Section 4.08
          of the Indenture, the undersigned hereby elects to have

          / /     the entire principal amount

          / /     $_________________ ($1,000 in principal amount or an integral
                 multiple thereof) of this Note

          repurchased by the Company.  The undersigned hereby directs the 
          Trustee or Paying Agent to pay it or ____________________ an amount
          in cash equal to 100% of the principal amount indicated in the
          preceding sentence, plus accrued and unpaid interest thereon, if any,
          to the Asset Sale Payment Date.

Dated: 
       -------------------

- --------------------------------       ---------------------------------------
Signature of Holder                    Signature Guaranteed by an institution
                                       member of the Signature Guaranty 
                                       Medallion Program



NOTICE:  The signature to the foregoing must correspond to the Name as written 
upon the face of this Note in every particular, without alteration or any change
whatsoever.


                                   B-11

<PAGE>

   
                                   EXHIBIT C

                             SUBSIDIARY GUARANTEE

     This Subsidiary Guarantee, dated as of ___________________, (this 
"Subsidiary Guarantee" and together with all such guarantees delivered from
time to time under Article XI of the Indenture referred to below being 
referred to herein as the "Subsidiary Guarantees") is made by ____ and _____ 
(each a "Subsidiary Guarantor" and collectively, the "Subsidiary Guarantors") 
in favor of STATE STREET BANK AND TRUST COMPANY as Trustee (together with its 
successors and assigns in such capacity, the "Trustee") under the Indenture 
(as amended or modified from time to time, the "Indenture") dated as of _____, 
1996 made by Costilla Energy, Inc., a Delaware corporation (the "Company"), 
pursuant to which the Company issued its __% Senior Subordinated Notes due 
2006 (the "Notes"). Unless otherwise defined herein, capitalized terms used 
herein have the meanings assigned to such terms in the Indenture.

     WHEREAS, pursuant to Section 4.12(b) of the Indenture, each Subsidiary 
Guarantor is prohibited from incurring certain Indebtedness without executing 
and delivering a Subsidiary Guarantee; and 

     WHEREAS, the Subsidiary Guarantor wishes to incur such Indebtedness; 

     NOW THEREFORE, in consideration of the premises and other good and 
valuable consideration, the receipt and sufficiency of which are hereby 
acknowledged, the Subsidiary Guarantor agrees as follows:

     SECTION 1.  UNCONDITIONAL GUARANTEE.

     Each Subsidiary Guarantor hereby, jointly and severally, unconditionally 
guarantees to each Holder and to the Trustee the due and punctual payment of 
the principal of, premium, if any, and interest on the Notes and all other 
amounts due and payable under the Indenture and the Notes by the Company, 
whether at maturity, by acceleration, redemption, repurchase or otherwise, 
including, without limitation, interest on the 
    

                                   C-1

<PAGE>

   
overdue principal of, premium, if any, and interest on the Notes, to the extent
lawful, all in accordance with the terms hereof and thereof; subject, however,
to the limitations set forth in Section 2.

     Failing payment when due of any amount so guaranteed for whatever 
reason, the Subsidiary Guarantors will be jointly and severally obligated to 
pay the same immediately.  Each Subsidiary Guarantor hereby agrees that its 
obligations hereunder shall be unconditional irrespective of the validity, 
regularity or enforceability of the Notes or the Indenture, the absence of 
any action to enforce the same, any waiver or consent by any Holder of the 
Notes with respect to any provisions hereof or thereof, the recovery of any 
judgment against the Company, any action to enforce the same or any other 
circumstance which might otherwise constitute a legal or equitable discharge 
or defense of any Subsidiary Guarantor.  Each Subsidiary Guarantor hereby 
waives diligence, presentment, demand of payment, filing of claims with a 
court in the event of insolvency or bankruptcy of the Company, any right to 
require a proceeding first against the Company, protest, notice and all 
demands whatsoever and covenants that this Subsidiary Guarantee will not be 
discharged except by complete performance of the obligations contained in the 
Notes, this Indenture and in this Subsidiary Guarantee.  If any Holder or the 
Trustee is required by any court or otherwise to return to the Company, any 
Subsidiary Guarantor, or any custodian, trustee, liquidator or other similar 
official acting in relation to the Company or any Subsidiary Guarantor, any 
amount paid by the Company or any Subsidiary Guarantor to the Trustee or such 
Holder, this Subsidiary Guarantee, to the extent theretofore discharged, 
shall be in full force and effect.  Each Subsidiary Guarantor agrees it shall 
not be entitled to any right of subrogation in relation to the Holders in 
respect of any obligations guaranteed hereby until payment in full of all 
obligations guaranteed hereby.  Each Subsidiary Guarantor further agrees 
that, as between each Subsidiary Guarantor, on the one hand, and the Holders 
and the Trustee, on the other hand, (x) the maturity of the obligations 
guaranteed hereby may be accelerated as provided in Article VI of the 
Indenture for the purposes of this Subsidiary Guarantee, notwithstanding any 
stay, injunction or other prohibition preventing such acceleration in respect 
of the obligations guaranteed hereby, and (y) in the event of any 
acceleration of such obligations as provided in Article VI of the Indenture 
and subject to the rescission thereof as provided therein, such obligations 
(whether or not due and payable) shall forthwith become due and payable by 
each Subsidiary Guarantor for the purpose of this Subsidiary Guarantee. 

     SECTION 2. LIMITATION OF SUBSIDIARY GUARANTOR'S LIABILITY.

     Each Subsidiary Guarantor and by its acceptance of its Note each Holder 
hereby confirms that it is the intention of all such parties that the 
guarantee by such Subsidiary Guarantor pursuant to its Subsidiary Guarantee 
not constitute a fraudulent transfer or conveyance for purposes of the 
Federal Bankruptcy Code, the Uniform Fraudulent Conveyance Act, the Uniform 
Fraudulent Transfer Act or any similar federal, state or foreign law.  To 
effectuate the foregoing intention, the Holders and each Subsidiary Guarantor 
irrevocably agree that the obligations of each Subsidiary Guarantor under the 
Subsidiary Guarantees shall be limited to the maximum amount as will, after 
giving effect to all other contingent and fixed liabilities of such 
Subsidiary Guarantors and after giving effect to any collections from or 
payments made by or on behalf of any other Subsidiary Guarantor in respect of 
the obligations of such other Subsidiary Guarantor under its Subsidiary 
Guarantees or pursuant to 
    


                                   C-2


<PAGE>

   
Section 3, result in the obligations of such Subsidiary Guarantor under 
its Subsidiary Guarantee not constituting a fraudulent conveyance or 
fraudulent transfer under federal, state or foreign law.  This Section 2 
is for the benefit of the creditors of each Subsidiary Guarantor, and, for 
purposes of the Federal Bankruptcy Code, the Uniform Fraudulent Conveyance 
Act, the Uniform Fraudulent Transfer Act and each other similar federal, 
state or foreign law, any Indebtedness of a Subsidiary Guarantor incurred 
from time to time pursuant to the Credit Facility shall be deemed to have 
been incurred prior to the incurrence by such Subsidiary Guarantor of 
liability under its Subsidiary Guarantee.

     SECTION 3. CONTRIBUTION.  In order to provide for just and equitable 
contribution among the Subsidiary Guarantors, the Subsidiary Guarantors 
agree, INTER SE, that in the event any payment or distribution is made by any 
Subsidiary Guarantor (a "Funding Guarantor") under the Subsidiary Guarantees, 
such Funding Guarantor shall be entitled to a contribution from each other 
Subsidiary Guarantor in a pro rata amount based on the Adjusted Net Assets of 
each Subsidiary Guarantor (including the Funding Guarantor) for all payments, 
damages and expenses incurred by the Funding Guarantor in discharging the 
Company's obligations with respect to the Notes or, subject to this Section 3,
any other Subsidiary Guarantor's obligations with respect to the Subsidiary 
Guarantees.

     SECTION 4.  SUBSIDIARY GUARANTEES SUBORDINATED TO GUARANTOR SENIOR 
INDEBTEDNESS.  Each Subsidiary Guarantor agrees, and each Holder by accepting 
a Note agrees, that the Indebtedness evidenced by its Subsidiary Guarantee is 
subordinate and subject in right of payment, to the extent and in the manner 
provided in this Subsidiary Guarantee, to the prior payment in full of all 
Guarantor Senior Indebtedness (whether outstanding on the date hereof or 
hereafter created, incurred, assumed or guaranteed), and that the 
subordination is for the benefit of the holders of Guarantor Senior 
Indebtedness, PROVIDED, HOWEVER, that the Subsidiary Guarantee of such 
Subsidiary Guarantor, the Indebtedness represented thereby and the payment of 
the principal of (and premium, if any, on) and the interest on the Notes 
pursuant to such Subsidiary Guarantee in all respects shall rank PARI PASSU 
with, or prior to, all existing and future unsecured indebtedness (including, 
without limitation, Indebtedness) of such Subsidiary Guarantor that is 
subordinated to its Guarantor Senior Indebtedness.  This Subsidiary Guarantee 
shall constitute a continuing offer to all Persons who become holders of, or 
continue to hold, Guarantor Senior Indebtedness, and such provisions are made 
for the benefit of the holders of Guarantor Senior Indebtedness.

     SECTION 5.  LIQUIDATION; DISSOLUTION; BANKRUPTCY.  Upon any 
distribution to creditors of any Subsidiary Guarantor in a liquidation or 
dissolution of such Subsidiary Guarantor or in a bankruptcy, reorganization, 
insolvency, receivership or similar proceeding relating to any Subsidiary 
    

                                   C-3


<PAGE>

   
Guarantor or its property, in an assignment for the benefit of creditors or 
any marshaling of any Subsidiary Guarantor's assets and liabilities:

     (a)  holders of such Subsidiary Guarantor's Guarantor Senior 
Indebtedness shall be entitled to receive payment in full in cash of all 
Obligations due in respect of such Guarantor Senior Indebtedness (including 
interest after the commencement of any such proceeding at the rate specified 
in the applicable Guarantor Senior Indebtedness) before Holders shall be 
entitled to receive any payment with respect to such Subsidiary Guarantor's 
Subsidiary Guarantee (except that Holders may receive (i) securities that are 
subordinated to at least the same extent as such Subsidiary Guarantor's 
Subsidiary Guarantee to (A) Guarantor Senior Indebtedness and (B) any 
securities issued in exchange for Guarantor Senior Indebtedness and (ii) 
payments and other distributions made from any defeasance trust created 
pursuant to Section 8.01 of the Indenture); and

     (b)  until all Obligations with respect to such Subsidiary Guarantor's 
Guarantor Senior Indebtedness (as provided in subsection (a) above) are paid 
in full in cash, any distribution to which Holders would be entitled but for 
this Article shall be made to holders of Guarantor Senior Indebtedness 
(except that Holders may receive (i) securities that are subordinated to at 
least the same extent as such Subsidiary Guarantor's Subsidiary Guarantee to 
(A) Guarantor Senior Indebtedness and (B) any securities issued in exchange 
for Guarantor Senior Indebtedness and (ii) payments and other distributions 
made from any defeasance trust created pursuant to Section 8.01 of the 
Indenture), as their interests may appear.

     SECTION 6.  DEFAULT ON DESIGNATED GUARANTOR SENIOR INDEBTEDNESS.  No 
Subsidiary Guarantor may make any payment or distribution to the Trustee or 
any Holder in respect of Obligations with respect to such Subsidiary 
Guarantor's Subsidiary Guarantee and may not acquire from the Trustee or any 
Holder any Notes for cash or property (other than (i) securities that are 
subordinated to at least the same extent as such Subsidiary Guarantor's 
Subsidiary Guarantee to (A) Guarantor Senior Indebtedness and (B) any 
securities issued in exchange for Guarantor Senior Indebtedness and (ii) 
payments and other distributions made from any defeasance trust created 
pursuant to Section 8.01 of the Indenture) until all principal and other 
Obligations with respect to the Guarantor Senior Indebtedness have been paid 
in full if:

     (a)  a default in the payment of any principal, premium, if any, or 
interest with respect to Guarantor Designated Senior Indebtedness occurs and 
is continuing beyond any applicable grace period in the agreement, indenture 
or other document governing such Designated Guarantor Senior Indebtedness; or

     (b)  a default, other than such payment default, on Designated Guarantor 
Senior Indebtedness occurs and is continuing that then permits holders of such
Designated Guarantor Senior Indebtedness to accelerate its maturity and the 
Trustee receives a notice of such default (a "Subsidiary Guarantor Payment 
Blockage Notice") from a Person who may give it pursuant to Section 13 
hereof.  If the Trustee receives any such Subsidiary Guarantor Payment 
Blockage Notice, no subsequent Subsidiary Guarantor Payment Blockage Notice 
shall be effective for purposes of this 
    
                                   C-4


<PAGE>

   
Section 6 unless and until at least 360 days shall have elapsed since the 
effectiveness of the immediately prior Subsidiary Guarantor Payment Blockage 
Notice.  No default specified in this clause (b) that existed or was continuing
on the date of delivery of any Subsidiary Guarantor Payment Blockage Notice to
the Trustee shall be, or be made, the basis for a subsequent Subsidiary 
Guarantor Payment Blockage Notice.

     Such Subsidiary Guarantor may and shall resume payments on and 
distributions in respect of its Subsidiary Guarantee and may acquire them 
upon the earlier of:

          (i)  in the case of a default referred to in Section 6(a), the 
     date upon which such default is cured or waived, or

          (ii)  in the case of a default referred to in Section 6(b) hereof,
     the earlier of the date on which such default is cured or waived or 179 
     days after the date on which the applicable Subsidiary Guarantor Payment 
     Blockage Notice is received, unless the maturity of such Designated
     Guarantor Senior Indebtedness has been accelerated,

if, and only if,  this Subsidiary Guarantee otherwise permits the payment, 
distribution or acquisition at the time of such payment or acquisition.

     SECTION 7.  WHEN DISTRIBUTION MUST BE PAID OVER.  In the event that the 
Trustee or any Holder receives any payment of any Obligations with respect to 
any Subsidiary Guarantee at a time when the Trustee or such Holder, as 
applicable, has actual knowledge that such payment is prohibited by Section 5 
or 6 hereof, such payment shall be held by the Trustee or such Holder, in 
trust for the benefit of, and shall be paid forthwith over and delivered, 
upon written request, to, the holders of Guarantor Senior Indebtedness of the 
applicable Subsidiary Guarantor as their interests may appear or their 
Representative under the indenture or other agreement (if any) pursuant to 
such Guarantor Senior Indebtedness may have been issued, for application to 
the payment of all Obligations with respect to such Subsidiary Guarantor's 
Guarantor Senior Indebtedness remaining unpaid to the extent necessary to pay 
such Obligations in full in accordance with their terms, after giving effect 
to any concurrent payment or distribution to or for the holders of such 
Subsidiary Guarantor's Guarantor Senior Indebtedness.

     With respect to the holders of any Guarantor Senior Indebtedness, the 
Trustee undertakes to perform only such obligations on the part of the 
Trustee as are specifically set forth in this Subsidiary Guarantee, and no 
implied covenants or obligations with respect to the holders of any Guarantor 
Senior Indebtedness shall be read into this Subsidiary Guarantee against the 
Trustee.  The Trustee shall not be deemed to owe any fiduciary duty to the 
holders of Guarantor Senior Indebtedness, and shall not be liable to any such 
holders if the Trustee shall pay over or distribute to or on behalf of 
Holders or the Company or any other Person money or assets to which any 
holders of Guarantor Senior Indebtedness shall be entitled by virtue of this 
Subsidiary Guarantee, except if such payment is made as a result of the 
willful misconduct or gross negligence of the Trustee. 
    

                                        C-5

<PAGE>
   
     SECTION 8.  NOTICE BY SUBSIDIARY GUARANTOR.  Each Subsidiary Guarantor 
shall promptly notify the Trustee and the Paying Agent of any facts known to 
such Subsidiary Guarantor that would cause a payment of any Obligations with 
respect to such Subsidiary Guarantor's Subsidiary Guarantee to violate this 
Subsidiary Guarantee, but failure to give such notice shall not affect the 
subordination of such Subsidiary Guarantor's Subsidiary Guarantee to such 
Subsidiary Guarantor's Guarantor Senior Indebtedness as provided in this 
Subsidiary Guarantee.

     SECTION 9.  SUBROGATION.  After all Guarantor Senior Indebtedness of a 
Subsidiary Guarantor is paid in full and until the Notes are paid in full, 
Holders shall be subrogated (equally and ratably with all other Indebtedness 
of such Subsidiary Guarantor PARI PASSU the Notes) to the rights of holders 
of such Guarantor Senior Indebtedness to receive distributions applicable to 
such Guarantor Senior Indebtedness to the extent that distributions otherwise 
payable to the Holders have been applied to the payment of such Guarantor 
Senior Indebtedness.  A distribution made under this Subsidiary Guarantee to 
holders of such Guarantor Senior Indebtedness that otherwise would have been 
made to Holders is not, as between such Subsidiary Guarantor and Holders, a 
payment by such Subsidiary Guarantor on its Subsidiary Guarantee.

     SECTION 10.  RELATIVE RIGHTS.  This Subsidiary Guarantee defines the 
relative rights of Holders and holders of Guarantor Senior Indebtedness.  
Nothing in this Subsidiary Guarantee shall:

          (i)  impair, as between the Subsidiary Guarantors and Holders, the 
     obligation of the Subsidiary Guarantors, which is absolute and 
     unconditional, to pay principal of, premium, if any, on and interest on 
     the Subsidiary Guarantees in accordance with their terms;

          (ii)  affect the relative rights of Holders and creditors of the 
     Subsidiary Guarantors other than their rights in relation to holders of 
     Guarantor Senior Indebtedness; or

          (iii)  prevent the Trustee or any Holder from exercising its 
     available remedies upon a Default or Event of Default, subject to the 
     rights of holders and owners of Guarantor Senior Indebtedness to receive 
     distributions and payments otherwise payable to Holders.

     If the Subsidiary Guarantors fail because of this Subsidiary Guarantee 
to pay principal of, premium, if any, on or interest on a Note on the due 
date, the failure is still a Default or Event of Default.

     SECTION 11.  NO IMPAIRMENT OF SUBORDINATION BY SUBSIDIARY GUARANTORS 
OR HOLDERS.  (a) No right of any holder of Guarantor Senior Indebtedness to 
enforce the subordination of the Indebtedness evidenced by any Subsidiary 
Guarantor's Subsidiary Guarantee shall be impaired by any act or failure to 
act by such Subsidiary Guarantor or any Holder or by the failure of 
Subsidiary Guarantors or any Holder to comply with this Indenture.

     (b) Without in any way limiting the generality of paragraph (a) of this 
Section, the holders of any Guarantor Senior Indebtedness, may, at any time 
and from time to time, without the consent of or notice to the Trustee or the 
Holders, without incurring responsibility to the Holders and without 
impairing or releasing the subordination or other benefits provided in this 
Subsidiary Guarantee, or the obligations hereunder of the Holders to the 
holders of Guarantor Senior Indebtedness, do any one or more of the 
following: (i) change the manner, place or terms of payment or extend the 
time of payment of, or renew, exchange, amend, increase or alter, Guarantor 
Senior Indebtedness or the terms of any instrument evidencing the same or any 
agreement under which Guarantor Senior Indebtedness is outstanding or any 
liability of any obligor thereon (unless such change, extension, amendment, 
increase or other alteration results in such Indebtedness no longer being 
Guarantor Senior Indebtedness as defined in the Indenture and this Subsidiary 
Guaranty); (ii) sell, exchange, release or otherwise deal with any Property 
pledged, mortgaged or otherwise securing Guarantor Senior Indebtedness; 
(iii) settle or compromise any Guarantor Senior Indebtedness or any liability 
of any obligor thereon or release any Person liable in any manner for the 
collection of Guarantor Senior Indebtedness; and (iv) exercise or refrain 
from exercising any rights against the Company and any other Person.

     SECTION 12.  DISTRIBUTION OR NOTICE TO REPRESENTATIVE.  Whenever a 
distribution is to be made or a notice given to holders of Guarantor Senior 
Indebtedness, the distribution may be made and the notice given to their 
Representative.
    
                                     C-6
<PAGE>

   
     Upon any payment or distribution of assets of any Subsidiary Guarantor 
referred to in this Subsidiary Guarantee, the Trustee and the Holders shall 
be entitled to rely upon any order or decree made by any court of competent 
jurisdiction or upon any certificate of such Representative or of the 
liquidating trustee or agent or other Person making any distribution to the 
Trustee or to the Holders for the purpose of ascertaining the Persons 
entitled to participate in such distribution, the holders of such Guarantor 
Senior Indebtedness and other Indebtedness of such Subsidiary Guarantor, the 
amount thereof or payable thereon, the amount or amounts paid or distributed 
thereon and all other facts pertinent thereto or to this Subsidiary Guarantee.

     The Trustee shall be entitled to rely on the delivery to it of a written 
notice by a Person representing himself to be a holder of Guarantor Senior 
Indebtedness (or a trustee or agent on behalf of such holder) to establish 
that such notice has been given by a holder of such Guarantor Senior 
Indebtedness (or a trustee or agent on behalf of any such holder).  In the 
event that the Trustee determines in good faith that further evidence is 
required with respect to the right of any Person as a holder of such 
Guarantor Senior Indebtedness to participate in any payment or distribution 
pursuant to this Subsidiary Guarantee, the Trustee may request such Person to 
furnish evidence to the reasonable satisfaction of the Trustee as to the 
amount of such Guarantor Senior Indebtedness held by such Person, the extent 
to which such Person is entitled to participate in such payment or 
distribution and any other facts pertinent to the rights of such Person under 
this Subsidiary Guarantee, and if such evidence is not furnished, the Trustee 
may defer any payment which it may be required to make for the benefit of 
such Person pursuant to the terms of this Indenture pending judicial 
determination as to the rights of such Person to receive such payment.

     SECTION 13.  RIGHTS OF TRUSTEE AND PAYING AGENT.  Notwithstanding the 
provisions of any Subsidiary Guarantee or any other provision of the 
Indenture, the Trustee shall not be charged with knowledge of the existence 
of any facts that would prohibit the making of any payment or distribution by 
the Trustee, and the Trustee and the Paying Agent may continue to make 
payments on the Notes, unless the Trustee shall have received at its 
Corporate Trust Office at least two Business Days prior to the date of such 
payment written notice of facts that would cause the payment of any 
Obligations with respect to any Subsidiary Guarantee to violate this 
Subsidiary Guarantee. Only the holders of Designated Guarantor Senior 
Indebtedness or a Representative thereof may give the notice.  Nothing in 
this Subsidiary Guarantee shall impair the claims of, or payments to, the 
Trustee under or pursuant to Section 7.07 of the Indenture.

     The Trustee in its individual or any other capacity may hold Guarantor 
Senior Indebtedness with the same rights it would have if it were not 
Trustee.  Any Paying Agent may do the same with like rights.

     SECTION 14.  AUTHORIZATION TO EFFECT SUBORDINATION.  Each Holder of a 
Note by the Holder's acceptance thereof authorizes and directs the Trustee on 
the Holder's behalf to take such action as may be necessary or appropriate to 
effectuate the subordination as provided in this Subsidiary Guarantee, and 
appoints the Trustee to act as the Holder's attorney-in-fact for any and all 
such purposes.  If the Trustee does not file a proper proof of claim or proof 
of debt in the form required in any 
    

                                     C-7
<PAGE>

   
judicial proceeding relative to any Subsidiary Guarantor (or any other 
obligor upon the Notes), its creditors or its property at least 30 days 
before the expiration of the time to file such claim, any Representative is 
hereby authorized to file an appropriate claim for and on behalf of the 
Holders of the Notes.

     SECTION 15.  AMENDMENTS.  The provisions of this Subsidiary Guarantee 
shall not be amended or modified except in accordance with Article IX of the 
Indenture.
    
                                      C-8

<PAGE>

   
     SECTION 16.  REPRESENTATIONS AND WARRANTIES.  Each Subsidiary Guarantor 
hereby represents and warrants as follows: 

     (a) Such Subsidiary Guarantor is (i) a                duly organized, 
validly existing and in good standing under the laws of the jurisdiction of 
its incorporation, (ii) has all requisite power and authority to own or lease 
and operate its properties and to carry on its business as now conducted and 
as proposed to be conducted; and (iii) is duly qualified or licensed to do 
business as a foreign corporation and is in good standing in all 
jurisdictions in which it owns or leases assets and property or in which the 
conduct of its business requires it to so qualify or be licensed except where 
the failure to so qualify or be licensed would not have a material adverse 
effect on the operations, business, prospects, assets, properties or 
condition (financial or other) of the Company and its Subsidiaries, including 
such Guarantor, considered as one enterprise.

     (b) The execution, delivery and performance by such Subsidiary Guarantor 
of this Subsidiary Guarantee, have been duly authorized by all necessary 
corporate action on the part of such Subsidiary Guarantor and do not and will 
not violate any provision of the articles or certificate of incorporation or 
by-laws or other charter documents of such Subsidiary Guarantor and do not and
will not
    

                                        C-9
<PAGE>

   
violate, or be in conflict with, or constitute a default under, or permit the 
termination of, or result in the creation of any Lien (other than a Permitted 
Lien) upon any property of such Subsidiary Guarantor under (x) any statute or 
law or any judgment, decree, order, regulation or rule of any court or 
governmental authority to which such Subsidiary Guarantor or any of its 
properties may be subject, or (y) any contract, indenture, mortgage, loan 
agreement, note, lease or other agreement or instrument to which such 
Subsidiary Guarantor is a party or by which it may be bound, or to which any 
of its properties may be subject, which conflict, default, termination or 
Lien would have a material adverse effect upon the operations, business, 
prospects, assets, properties or condition (financial or other) of the 
Company and its Subsidiaries, including such Subsidiary Guarantor, considered 
as one enterprise, or except as set forth in the Disclosure Statement. This 
Subsidiary Guarantee is the legal, valid and binding obligation of such 
Subsidiary Guarantor, enforceable against such Subsidiary Guarantor in 
accordance with its terms, except as enforcement thereof may be limited by 
bankruptcy, insolvency, reorganization or other similar laws affecting 
enforcement of creditors rights generally and except as enforcement thereof 
is subject to general principles of equity (regardless of whether enforcement 
is considered in a proceeding in equity or at law).

     (c) No authorization, consent, approval or other action by, and no 
notice to or filing with, any court, governmental, administrative or judicial 
authority or regulatory body (domestic or foreign) is required for the due 
execution, delivery or performance by such Subsidiary Guarantor of this 
Subsidiary Guarantee.

     SECTION 17.  ADDRESSES FOR NOTICES.  All notices, requests, demands and 
other communications provided for or permitted hereunder shall be in writing 
(including
    
                                     C-10
<PAGE>

   
telegraphic communication) and, if to any Subsidiary Guarantor, mailed or 
telegraphed or delivered to it, adressed to it at the address of the Company 
specified in the Indenture, if to Trustee, addressed to it at the address 
specified in the Indenture, or as to each party at such other address as 
shall be designated by such party in a written notice to each other party 
complying as to delivery with the terms of this Section 18.

     SECTION 18.  NO WAIVER; REMEDIES.  No failure on the part of the Trustee 
or any Holder, to exercise, and no delay in exercising, an right hereunder 
shall operate as a waiver thereof; nor shall any single or partial exercise 
of any right hereunder preclude any other or further exercise thereof or the 
exercise of any other right. The remedies herein provided are cumulative and 
not exclusive of any remedies provided by law or any other agreement.

     SECTION 19.  CONTINUING GUARANTY; TRANSFER OF NOTES; TERMINATION OF 
GUARANTY. (a) This Subsidiary Guarantee is a continuing guaranty and, subject 
to the provisions of subsection (b) below, shall (i) remain in full force and 
effect until payment in full of the Obligations and all other amounts payable 
under this Subsidiary Guarantee, (ii) be binding upon each Subsidiary 
Guarantor, its successors and assigns, and (iii) inure to the benefit of and 
be enforceable by the Trustee and its successors, transferees and assigns.

     (b) All obligations of a particular Subsidiary Guarantor hereunder shall 
automatically terminate as set forth in Section 11.02 of the Indenture.

                                     C-11
<PAGE>

enforceable in such jurisdiction and such illegal, invalid or unenforceable 
provision shall be legal, valid and enforceable in all other jurisdictions.

     SECTION 20.  GOVERNING LAW.  This Subsidiary Guarantee shall be governed 
by, and construed in accordance with, the law of the State of New York, 
United States.

     SECTION 21.  SEVERABILITY.  In case any provision of this Subsidiary 
Guarantee shall be invalid, illegal or unenforceable, that portion of such 
provision that is not invalid, illegal or unenforceable shall remain in 
effect, and the validity, legality, and enforceability of the remaining 
provisions shall not in any way be affected or impaired thereby.

     IN WITNESS WHEREOF, each Subsidiary Guarantor has caused this Subsidiary 
Guarantee to be duly executed and delivered by its officer thereunto duly 
authorized as of the date first above written.

                                         [LIST OF SUBSIDIARY GUARANTORS]

                                         By: _________________
                                             Name and Title:

    
                                   C-12

<PAGE>
                                                                  EXHIBIT 5.1

                     COTTON, BLEDSOE, TIGHE & DAWSON
                       A PROFESSIONAL CORPORATION
                            ATTORNEYS AT LAW
                                SUITE 300
                           500 WEST ILLINOIS
                        MIDLAND, TEXAS 79701-4337
                       P.O. BOX 2776 ZIP 79702-2776
                         TELEPHONE (915) 684-5782
                            FAX (915) 682-3672


                              August 30, 1996



Costilla Energy, Inc.
400 West Illinois, Suite 1000
Midland, Texas 79701

Re: Registration Statement on Form S-1
    (Registration No. 333-08909)

Gentlemen:

   We have acted as counsel for Costilla Energy, Inc., a Delaware corporation 
(the "Company") in connection with the registration under the Securities Act 
of 1933, as amended (the "Act"), of $100,000,000 of ____% Senior Subordinated 
Notes due 2006 (the "Notes") of the Company to be sold to the several 
Underwriters to be named in Schedule 1 (collectively, the "Underwriters") 
attached to the Underwriting Agreement (the "Underwriting Agreement") to be 
entered into by and between the Underwriters, for whom NationsBanc Capital 
Markets, Inc. and Prudential Securities Incorporated are acting as 
representatives, the Company, and Costilla Energy, L.L.C.  A Registration 
Statement on Form S-1 (Registration No. 333-08909) covering the sale of the 
Notes was filed under the Act with the Securities and Exchange Commission (the 
"Commission") on July 26, 1996, as amended by Amendment No. 1 to be filed 
with the Commission on August 30, 1996 (the "Registration Statement").  

   In reaching the conclusions expressed in this opinion, we have examined 
signed copies of the Registration Statement and all exhibits thereto.  We 
have also examined and relied upon originals, or copies certified to our 
satisfaction, of (i) the Certificate of Incorporation

<PAGE>

Costilla Energy, Inc.
August  30, 1996
Page 2



and Bylaws of the Company, (ii) minutes and records of the corporate 
proceedings of the Company with respect to the issuance of the Notes and 
related matters, (iii) the form of Underwriting Agreement, and (iv) such other 
agreements and instruments relating to the Company as we have deemed necessary 
or appropriate for the purposes of the opinions hereinafter expressed.  In 
rendering such opinions, we have relied, to the extent we deemed reasonable, 
on certificates and certain other information provided to us by officers of the
Company and public officials as to matters of fact of which the maker of such 
certificates or the person providing such information had knowledge, without 
investigation into or verification of such information.  Furthermore, in 
rendering such opinions we have assumed that the signatures on all documents 
examined by us are genuine, that all documents and corporate record books 
submitted to us as originals are authentic, accurate and complete, and that all
documents submitted to use as copies are true, correct and complete copies of 
the originals thereof.  We have also assumed that the Underwriting Agreement 
will be executed in substantially the same form as presented to us.

   Based solely upon the foregoing, subject to the assumptions, limitations 
and qualifications set forth herein, and specifically limited in all respects 
to the laws of the State of Texas, of the United States of America and the 
General Corporation Law of the State of Delaware, we are of the opinion that 
the Notes registered pursuant to the Registration Statement have been duly 
and validly authorized by the Company and, when paid for, issued or sold and 
delivered in accordance with the terms of the Underwriting Agreement and the 
Registration Statement, will be binding obligations of the Company, subject 
to applicable bankruptcy, insolvency, reorganization, fraudulent transfer, 
moratorium or similar laws affecting creditors' rights severally and to 
general principles of equity and the availability of equitable remedies.  
Please note in this regard that we are not licensed to practice law in the 
State of Delaware, but have reviewed Delaware law in connection with the 
opinions expressed herein.

   We hereby consent to the use of this opinion as an exhibit to the 
Registration Statement and to the reference to this Firm under the caption 
"Legal Matters" in the Prospectus forming a part of the Registration 
Statement.  In giving this consent we do not thereby admit that we come 
within the category of persons whose consent is required under the Act or the 
rules and regulations of the Commission promulgated thereunder.

   This opinion is rendered only to the Company and solely for the benefit of 
the Company and the Commission in connection with the registration and the 
issuance of the Notes pursuant to the Registration Statement.  This opinion 
may not be otherwise used,


<PAGE>

Costilla Energy, Inc.
August  30, 1996
Page 3



circulated, quoted, relied upon, or referred to by you or the Commission for 
any other purpose or by any other person, firm or corporation for any 
purpose, without our prior written consent.


                                           Yours very truly,

                                   COTTON, BLEDSOE, TIGHE & DAWSON


                                   By:    /s/ Richard T. McMillan
                                      ------------------------------
                                           Richard T. McMillan



<PAGE>
                                                                EXHIBIT 10.1



August 23, 1996

Costilla Energy, Inc.
400 West Illinois Avenue, 10th Floor
Midland, Texas  79701
Attn: Michael J. Grella

Dear Mike:

We are pleased to advise you that NationsBank of Texas, N.A. ("NATIONSBANK") 
hereby commits (the "COMMITMENT"), subject to the terms and conditions 
outlined in this letter and in the Summary of Terms and Conditions attached 
hereto, incorporated herein and made a part hereof (collectively, this 
"COMMITMENT LETTER") that it will make available to you a credit facility in 
an amount up to $50,000,000 (the "CREDIT FACILITY").  Proceeds of the Credit 
Facility will be used as provided in the Summary of Terms and Conditions.

The Commitment is conditioned upon the preparation, execution and delivery of 
such documents in form and substance satisfactory to us and our counsel (the 
"DEFINITIVE DOCUMENTS"), upon the resolution to our satisfaction of any legal 
or structural issues in connection with the Credit Facility, and upon the 
absence of a material adverse change in Costilla's financial condition, 
operations, prospects or properties from that reflected in the information 
delivered to NationsBank or any of its affiliates in connection with the 
transaction contemplated by this Commitment Letter.  The Commitment is also 
subject to (i) the completion of such legal and financial review as we 
determine to be necessary, (ii) the absence of any factors which we determine 
from such review to adversely affect our ability to offer the Credit Facility 
as set forth in the attached Summary of Terms and Conditions, and (iii) the 
satisfaction of all conditions set forth in this Commitment Letter.

Neither this Commitment Letter nor the Commitment is assignable by you.  
Nothing in this Commitment Letter, express or implied, shall give any person, 
other than the parties hereto, any benefit or any legal or equitable right, 
remedy or claim under this Commitment Letter.  Furthermore, this Commitment 
Letter is confidential and may not be disclosed to any person or entity 
except Costilla's officers, directors, employees and professional advisors.

<PAGE>

Mr. Michael J. Grella
August 23, 1996
Page 2



Costilla agrees to pay NationsBank the fees and expenses as set forth in the 
attached Summary of Terms and Conditions.  In addition, Costilla agrees to 
indemnify and hold NationsBank and its affiliates harmless from and against 
any and all liabilities, claims, losses, damages, penalties, costs, or 
expenses (including without limitation, reasonable fees and expenses of 
counsel)  of any kind or nature whatsoever which in any way or to any extent 
may be imposed on, incurred by, or asserted against us in connection with 
this Commitment Letter, the Definitive Documents, or any of the negotiations, 
transactions and events at any time associated therewith or contemplated 
therein except for any of the foregoing arising from the gross negligence or 
willful misconduct of NationsBank or its affiliates, and upon demand from 
time to time, to reimburse NationsBank and its affiliates for all reasonable 
out-of-pocket costs, expenses and other payments, including but not limited 
to, reasonable legal fees and disbursements incurred or made in connection 
with the Commitment and the preparation, execution and delivery of the 
Definitive Documents, regardless of whether or not the Definitive Documents 
are executed.

Additionally, Costilla agrees to allow NationsBank or any of its affiliates 
to reference this Commitment for the benefit of promoting NationsBank or such 
affiliate.

This Commitment Letter (including the attached Summary of Terms and 
Conditions) sets forth the entire understanding of the parties as to the 
scope of the Commitment and the obligation of NationsBank with respect 
thereto.  The Commitment will expire at 5:00 PM Midland, Texas time on August 
26, 1996 unless accepted prior to such time.  The Commitment will also expire 
on October 4, 1996 if by such date you have not executed and delivered 
Definitive Documents acceptable to us as contemplated in the attached Summary 
of Terms and Conditions.

This Commitment Letter shall be governed by, and construed in accordance 
with, the laws of the State of Texas as applied to contracts made and 
performed within such state, without giving effect to the principles of 
conflicts of laws thereof.  To the fullest extent permitted by applicable 
law, each of NationsBank and Costilla hereby irrevocably submit to the 
jurisdiction of any Texas court or Federal court sitting in Texas, in respect 
of any suit, action or proceeding arising out of or relating to the 
Commitment, this Commitment Letter or the Definitive Documents and agree that 
any such suit, action or proceeding may be heard and determined in any such 
court.  Each of NationsBank and Costilla waive, to the fullest extent 
permitted by applicable law, any objection which it may now or hereafter have 
to the laying of the venue of any such suit, action or proceedings brought in 
any such court, and any claim that any such suit, action or proceeding 
brought in any such court has been brought in an inconvenient forum.

Please indicate your acceptance of the Commitment and your agreement to the 
matters contained in this Commitment Letter by executing this document and 
returning it to us at


<PAGE>

Mr. Michael J. Grella
August 23, 1996
Page 3



or before 5:00 PM August 28, 1996, together with one-fifth of the 
underwriting fee ($50,000) due upon your execution of this Commitment Letter 
with the remainder payable at closing.


Sincerely,

NATIONSBANK OF TEXAS, N.A.


   
By:      /s/  Frank K. Stowers       
    
    -------------------------------- 
    Name:   Frank K. Stowers
    Title:  Vice President



ACCEPTED AND AGREED TO
as of the date first written above

COSTILLA ENERGY, INC.


   
By:     /s/  Michael J. Grella       
    -------------------------------- 
    Name:   Michael J. Grella        
    Title:  President 
    



<PAGE>
   
                        SUMMARY OF TERMS AND CONDITIONS

                                AUGUST 23, 1996

BORROWER:                Costilla Energy, Inc., a Delaware corporation.

AGENT:                   NationsBank of Texas, N.A. ("NATIONSBANK").

ARRANGER:                NationsBanc Capital Markets, Inc. ("NCMI").

LENDERS:                 NationsBank and other financial institutions acceptable
                         to Agent, NCMI and Borrower.

ISSUING LENDER:          NationsBank.

AMOUNT AND TYPE          Revolving Line of Credit in an amount equal to the 
OF CREDIT FACILITY:      Borrowing Base; the initial Borrowing Base will be 
                         $50,000,000.  Prior to the second anniversary date of
                         the Credit Facility, the Borrowing Base will be 
                         redetermined periodically and increased or decreased in
                         the manner described below, but in no event will the 
                         Borrowing Base ever exceed $125,000,000.

                         Beginning on the second anniversary of the date of 
                         the Credit Facility, the Borrowing Base will be 
                         redetermined periodically and may be decreased, but 
                         will not be increased above the amount of the Borrowing
                         Base in effect immediately prior to such 
                         redetermination.  In addition, the Borrowing Base will
                         be further reduced each quarter by an amount equal to
                         one-twelfth of the Borrowing Base in effect on such
                         second anniversary date.
                         
PURPOSE:                 Borrower will use all proceeds of the Credit Facility 
                         for (i) working capital in its existing lines of 
                         business (which include the exploration, operation and 
                         development of oil and gas properties), (ii) 
                         acquisition of oil and gas reserves, and (iii) issuance
                         of letters of credit (sub-limit on letter of credit
                         issuance of $1,000,000).
    

- -------------------------------------------------------------------------------
Costilla Energy, Inc.                    Page 1                     NationsBank
<PAGE>
   

INTEREST RATE:           Agent's fluctuating "Base Rate" (defined as the higher 
                         of Agent's Prime Rate and the Federal Funds Rate plus 
                         1/2%) plus the Applicable Base Rate Margin, based on a
                         360-day year, payable monthly.

                         Agent's reserve adjusted eurodollar rate for periods of
                         1, 2, 3, or 6 months, plus the Applicable Eurodollar 
                         Rate Margin, based on a 360 day year, payable quarterly
                         and at the end of each interest period.
                         
                         Interest on past due principal and interest shall be 
                         payable at the highest lawful rate.
                         
                         The Applicable Margins shall be based upon the 
                         outstanding balances of the Credit Facility, including
                         Letter of Credit Obligations, divided by the Borrowing
                         Base then in effect (expressed in basis points):
                         
<TABLE>
                                                  LESS THAN    GREATER THAN 50%    GREATER THAN 
                                                     50%        /LESS THAN 75%          75%     
                                                  ---------    ----------------    ------------ 
<S>                                               <C>          <C>                 <C>          
                         Base Rate Margin                0              0                 25    
                         Eurodollar Rate Margin        100          137.5              162.5    
</TABLE>

FEES:                    A commitment fee payable quarterly in arrears on the 
                         unutilized portion of the Borrowing Base, and
                         calculated based on a 360-day year (expressed in basis
                         points).
                         

<TABLE>
                                                  LESS THAN    GREATER THAN 50%    GREATER THAN 
                                                     50%        /LESS THAN 75%          75%     
                                                  ---------    ----------------    ------------ 
<S>                                               <C>          <C>                 <C>          
                         Commitment Fee              27.5              32.5             37.5    
</TABLE>

                         Underwriting fee of 50 bp; 20% due upon acceptance  of
                         the commitment and 80% due at closing of the Credit
                         Facility.
    

- -------------------------------------------------------------------------------
Costilla Energy, Inc.                    Page 2                     NationsBank

<PAGE>
   

                         A fee of 1/4% on any increase in the Borrowing Base.
                         
                         Letter of Credit Fees: (i) issuance fee for the account
                         of the Issuing Lender in the amount of  0.125% of the 
                         face amount of each letter of credit issued, and (ii) 
                         letter of credit fee for the pro rata accounts of the 
                         Lenders equal to the greater of (a) the Applicable 
                         Eurodollar Rate Margin per annum of the face amount of 
                         each letter of credit and (b) $500, payable at the time
                         of issuance.

                         Agent's fee of $50,000 per year.

AMORTIZATION/            Beginning on the second anniversary of the date of the 
MATURITY:                Credit Facility, quarterly payments of principal in the
                         amount necessary to cause the outstanding balance of 
                         the Credit Facility to equal the reduced Borrowing 
                         Base.  Due in full on the fifth anniversary of the 
                         Credit Facility.

OPTIONAL                 Permitted at any time without penalty, so long as no 
PREPAYMENTS:             principal bearing interest at a eurodollar rate is paid
                         before the end of the applicable interest period. 

BORROWING BASE           Prior to the second anniversary date of the Credit 
REDUCTIONS:              Facility, Borrower may reduce the Borrowing Base within
                         fifteen days after the date on which the Borrowing Base
                         is redetermined.

REQUIRED                 See requirements under Borrowing Base.
PREPAYMENTS:   

SECURITY AND SUPPORTING  First priority liens and assignments of production 
AGREEMENTS:              covering 70% of Borrower's oil and gas properties and 
                         all related contracts.

                         First priority security interest in and pledge of
                         Borrower's stock in Subsidiaries.

                         Negative Pledge on all other (i) oil and gas properties
                         of Borrower and Subsidiaries and (ii) 
    
- -------------------------------------------------------------------------------
Costilla Energy, Inc.                    Page 3                     NationsBank
<PAGE>
   

                         stock of Subsidiaries now or hereafter owned by 
                         Borrower, and Agreement to Pledge such properties or 
                         stock upon request.

                         All security documentation will be prepared by Agent's
                         counsel and must be satisfactory to Agent and Lenders 
                         in form and substance. 

TITLE ASSURANCES:        Legal opinions or other title assurances satisfactory 
                         to Agent covering certain oil and gas properties to be 
                         mortgaged and assurances from Borrower that title 
                         matters have not materially changed since the title 
                         review which occurred in connection with the 
                         NationsBridge facility.
                         
ENVIRONMENTAL REVIEW:    An environmental report on the oil and gas properties 
                         owned by Borrower, in form and substance and authorship
                         satisfactory to Agent and assurances from Borrower that
                         environmental matters have not materially changed since
                         the environmental due diligence which occurred in 
                         connection with the NationsBridge facility.
                         
BORROWING BASE:          The aggregate outstanding principal balance under the 
                         Credit Facility (including any letters of credit) may 
                         at no time exceed the Borrowing Base, which will be set
                         semi-annually by Agent and Lenders in their sole 
                         discretion (Agent and Borrower shall each have the 
                         right to request additional Borrowing Base 
                         redeterminations but not more than once during any six 
                         month period).  All Borrowing Base redeterminations 
                         will be set by Majority Lenders provided that agreement
                         of 100% of the Lenders will be required to increase the
                         Borrowing Base.  Increases in the BB will not occur 
                         after the second anniversary date.

                         To assist Agent and Lenders in setting the Borrowing 
                         Base, Borrower will furnish by February 28 of each year
                         an annual engineering report on proved oil and gas 
                         properties of Borrower and Subsidiaries, dated as of 
                         January 1 of such year, and prepared by Williamson 
                         Petroleum 
    
- -------------------------------------------------------------------------------
Costilla Energy, Inc.                    Page 4                     NationsBank
<PAGE>
   

                         Consultants, Inc. or other independent petroleum 
                         engineers acceptable to Agent, and Borrower will 
                         furnish by July 31 of each year a supplemental in-house
                         engineering report effective as of July 1.
                         
                         Borrower will furnish to Agent and Lenders with these 
                         engineering reports a report of production and 
                         associated operating statements for the oil and gas
                         properties of Borrower.  Borrower will also furnish to
                         Agent and Lenders a quarterly report of production and
                         associated operating statements for the oil and gas
                         properties of Borrower.

                         If the Borrowing Base ever falls below the outstanding 
                         balance of the Credit Facility (the amount by which the
                         outstanding balance exceeds the Borrowing Base is 
                         herein called the "BORROWING BASE DEFICIENCY"), 
                         Borrower must either (i) prepay the Credit Facility in
                         the amount of the deficit within 10 days after notice
                         thereof by Agent, or elect within such period to repay
                         the Borrowing Base Deficiency in 6 equal consecutive
                         monthly installments which shall be in addition to
                         other principal payments due under the Credit Facility
                         or (ii) mortgage to Agent additional oil and gas
                         properties sufficient to cause an increase in the
                         Borrowing Base by the amount of such Borrowing Base
                         Deficiency.
                         
CONDITIONS OF LENDING:   1. Borrower shall have successfully completed (i) the
                         merger of Costilla Energy, L.L.C. into Costilla Energy,
                         Inc. (the "MERGER"), (ii) the public issuance of 10 
                         year subordinated debt in the net amount of at least
                         $100,000,000 and (iii) equity in the gross amount of at
                         least $60,000,000 upon terms and conditions outlined in
                         the Form S-1 Registration Statements filed with
                         Securities and Exchange Commission on July 26, 1996.

                         2. All documents governing the Credit Facility 
                         (including without limitation a Credit Agreement,
                         Promissory Note, and documents establishing the
                         security rights listed above) must be executed and
    
- -------------------------------------------------------------------------------
Costilla Energy, Inc.                    Page 4                     NationsBank
<PAGE>
   
                         delivered in forms acceptable to Agent and Lenders.

                         3. The Credit Facility and the loan documents must 
                         comply with all applicable laws, contracts, instruments
                         and governmental policies.

                         4. There must be no default at closing or any funding,
                         and all representations and warranties must then be 
                         true.

                         5. Receipt by Agent of:
                         
                            (a)  Closing certificates of senior officers of
                         Borrower, confirming that all representations and
                         warranties are true, that all closing conditions have
                         been satisfied, and such other matters as Agent may
                         specify.
                         
                            (b)  Certificates of public officials as to 
                         Borrower's and Subsidiaries' existence and good 
                         standing.

                            (c)  Such legal opinions of counsel for Borrower
                         and Subsidiaries, and satisfaction or resolution of
                         such other legal requirements or risks, as Agent and
                         its counsel may specify including but not limited to
                         opinions regarding the Merger and the associated
                         transfer of assets and the continuation of liens on
                         those assets.
                         
                            (d)  Title assurances as described above.
                         
                            (e)  Environmental review as described above.
                         
                         6.  There must be no material adverse change in the
                         financial condition, operations, prospects or
                         properties of Borrower or Subsidiaries from that
                         presented to Agent in connection herewith, and no
                         pending or threatened challenge thereto by governmental
                         officials or third parties.

REPRESENTATIONS AND      The Credit Agreement and other loan documents 
    
- -------------------------------------------------------------------------------
Costilla Energy, Inc.                    Page 6                     NationsBank
<PAGE>
   

WARRANTIES:              shall contain such representations and warranties that
                         Agent deems appropriate for this transaction, including
                         without limitation confirmation of various factors 
                         which Agent and Lenders have considered in making their
                         decision to enter into the Credit Facility.
                         
AFFIRMATIVE COVENANTS:   The Credit Agreement and other loan documents shall 
                         contain such affirmative covenants of Borrower and 
                         Subsidiaries as are usual and customary for 
                         transactions of this kind, including without limitation
                         the following affirmative covenants:

                         1.   Borrower will deliver the following financial
                         statements and reports:
                         
                              (a)  Annual audited consolidated financial
                         statements of Borrower and Subsidiaries (with
                         accountants' certificate of no default and officer's
                         certificate of no default) within 105 days after each
                         fiscal year.
                         
                              (b)  Quarterly unaudited consolidated (and
                         consolidating upon the request of Agent) financial
                         statements of Borrower and Subsidiaries (with officer's
                         certificate of no default) within 60 days after each
                         fiscal quarter.
                         
                              (c)  Reports outlined under "BORROWING BASE"
                         above.
                         
                         2.   Agent and Lenders will have general access to
                         information about Borrower and Subsidiaries.
                         
                         3.   Borrower will pay Agent's and Arranger's expenses,
                         including legal fees, in negotiating, syndicating, 
                         administering, enforcing, and defending the various 
                         loan documents and rights of Agent and Lenders 
                         thereunder, together with interest on amounts not 
                         timely paid to the extent permitted by law. Borrower 
                         will pay Lenders' expenses, including legal fees, in 
                         enforcing and 

    
- -------------------------------------------------------------------------------
Costilla Energy, Inc.                    Page 7                     NationsBank
<PAGE>
   

                         defending the various loan documents and Lenders' 
                         rights thereunder, together with interest on amounts 
                         not timely paid to the extent permitted by law.

                         4.   Borrower and Subsidiaries will maintain insurance
                         as is customary in industry and satisfactory to Agent.
                         
                         5.   All transactions among Borrower, Subsidiaries, 
                         Executives and their affiliates shall be on terms no 
                         more favorable than could be obtained from third 
                         parties in an arm's length transaction.

NEGATIVE COVENANTS:      The Credit Agreement and other loan documents shall 
                         contain such negative covenants of Borrower and 
                         Subsidiaries as are usual and customary for 
                         transactions of this type, including without limitation
                         the following negative covenants:
                         
                         1.   Debt (other than trade debt, taxes and other
                         current liabilities according to GAAP, but including
                         guaranties) of Borrower and Subsidiaries will be
                         limited to the Credit Facility, public subordinated
                         debt contemplated hereby, and other debt of Borrower
                         not to exceed $750,000.  Any intercompany debt will be
                         limited to customary intercompany accounts in an amount
                         to be determined.
                         
                         2.   Liens by Borrower and Subsidiaries will be limited
                         to those securing the Credit Facility, and to customary
                         statutory and inchoate liens.
                         
                         3.   Mergers by Borrower and Subsidiaries will be 
                         prohibited unless Borrower is the surviving entity and
                         no Default or Event of Default exists or occurs as a
                         result of such merger.
                         
                         4.   Sales of interests in Borrower's Subsidiaries will
                         be prohibited.  Sales of property by Borrower and its 
                         Subsidiaries will be generally prohibited, 

    
- -------------------------------------------------------------------------------
Costilla Energy, Inc.                    Page 8                     NationsBank
<PAGE>
   

                         EXCEPT THAT assets having an aggregate value of 
                         $750,000 may be sold during the six-month period 
                         following each redetermination of the Borrowing Base 
                         without consent of Lenders.  Borrower shall notify 
                         Agent of each such sale and Agent shall release such
                         property at Borrower's expense.  All other sales of 
                         property must be approved by Agent and Majority Lenders
                         and the Borrowing Base will be reduced by the value 
                         assigned by Lenders to such property.
                         
                         5.   Dividends and other payments to equity owners by 
                         Borrower are not permitted.
                         
                         6.   Investments (or acquisitions) by Borrower and
                         Subsidiaries will be limited to (i) high-grade cash
                         equivalents, (ii) investments in the Moldovan operation
                         in amount not to exceed $2,500,000 per year, (iii) oil
                         and gas reserves to which proved reserves are
                         attributable, (iv) Republic Gas Partners, L.L.C., in an
                         amount not to exceed $1,000,000, (v) existing
                         Promissory Notes from A & P Meter Service and Supply,
                         Inc., and (vi) oil and gas leases to which no proved
                         reserves are attributable in an amount not to exceed
                         $2,500,000 per year.  Investments by Borrower in its
                         subsidiaries (and loans by Borrower to its
                         subsidiaries) will generally be prohibited unless the
                         subsidiary has unconditionally guaranteed the Credit
                         Facility and granted to Agent first perfected liens and
                         security interests in all of its properties to secure
                         the Credit Facility.  Should a Borrowing Base
                         Deficiency or an Event of Default occur, the Agent
                         shall have the right to require that each Subsidiary
                         unconditionally guaranty the Credit Facility and grant
                         to Agent first perfected liens and security interests
                         in all of its assets to secure the Credit Facility.  In
                         the ordinary course of business, cash transfers to and
                         from Borrower's subsidiaries for  customary
                         intercompany accounts will be allowed in an amount to
                         be determined.  Loans and new lines of business will be
                         generally prohibited.
                         
    
- -------------------------------------------------------------------------------
Costilla Energy, Inc.                    Page 9                     NationsBank
<PAGE>
   
                         7.   Borrower's consolidated current ratio will not be
                         less than 1.0 to 1.0.  Current maturities of long term
                         debt will be excluded as current liabilities and up to
                         $10,000,000 of borrowing availability can be included
                         as a current asset.
                         
                         8.   After the transactions contemplated hereby,
                         Borrower's consolidated tangible net worth will not be
                         less than the sum of (i) $30,000,000 plus (ii) 50% of
                         Borrower's consolidated net income earned after June
                         30, 1996, plus (iii) 75% of net proceeds from the sale
                         of equity interests in Borrower after the closing of
                         the Credit Facility.

                         9.   Payments due under leases (other than oil and gas
                         leases) by Borrower and Subsidiaries shall not exceed 
                         $1,000,000 in any fiscal year.

                         10.  Commodity hedging shall be limited in any month 
                         to: (i)  100% of proved production for puts and (ii) 
                         75% of proved production for all other derivative 
                         products.

                         11.  Beginning September 30, 1996, Borrower's ratio of 
                         EBITDA to interest expense shall never be less than 
                         2.0 to 1. The calculation of EBITDA and interest 
                         expense will be based upon: (i) for the period ending
                         September 30, 1996 upon the immediately preceding
                         fiscal quarter annualized, (ii) for the period ending
                         December 31, 1996 the immediately preceding two fiscal
                         quarters annualized, (iii) for the period ending March
                         31, 1997 the immediately preceding three fiscal
                         quarters annualized, and (iv) for the period ending
                         June 30, 1997 and for each fiscal quarter thereafter,
                         the last four fiscal quarters.
                              
                         12.  Neither Borrower nor any of its Subsidiaries 
                         will, directly or indirectly, enter into, create, or 
                         otherwise allow to exist any contract or other
                         consensual restriction on the ability of any subsidiary
                         of Borrower: (i) to pay dividends or make other
                         distributions to Borrower, (ii) to redeem 

    
- -------------------------------------------------------------------------------
Costilla Energy, Inc.                    Page 10                    NationsBank
<PAGE>
   
                         equity interests held in it by Borrower, (iii) to repay
                         loans and other indebtedness owing by it to Borrower, 
                         or (iv) to transfer any of its assets to Borrower.
                         
EVENTS OF DEFAULT:       The Credit Agreement and other loan documents will 
                         contain such events of default as are usual and 
                         customary for transactions of this kind, including 
                         without limitation defaults in payment or performance 
                         under the Credit Facility, misrepresentations, 
                         cross-defaults to other debt instruments or material 
                         obligations, events of default related to ERISA and 
                         insolvency, change of ownership, change in management 
                         and any material adverse change affecting Borrower or 
                         any Subsidiary.

INDEMNIFICATION:         Borrower will generally indemnify Agent, NCMI, their 
                         affiliates and all Lenders under the Credit Facility 
                         against losses in connection with the Credit Facility 
                         and the rights provided to Agent and Lenders in 
                         connection therewith, including without limitation 
                         indemnification against costs and taxes related to the
                         making, commitment to make, failure to take down or 
                         prepayment of loans thereunder or the reservation of 
                         capital in connection therewith.
                         
GENERAL:                 1.   The loan documents will generally be governed by 
                         Texas law.

                         2.   The loan documents as ultimately executed will 
                         constitute the complete agreement of the parties 
                         thereto, without modification by this summary of terms
                         and conditions or any discussions among representatives
                         of Borrower, Agent, Lenders, or any other parties.
                         
                         3.   The loan documents will provide that the parties 
                         thereto will waive, to the maximum extent not 
                         prohibited by law, any right to a trial by jury or to
                         claim or recover special, exemplary, punitive or
                         consequential damages, under or in connection 
    
- -------------------------------------------------------------------------------
Costilla Energy, Inc.                    Page 11                    NationsBank
<PAGE>
   

                         with the loan documents as ultimately executed, or any
                         negotiations, transactions or events associated
                         herewith or therewith or contemplated hereby or
                         thereby.
                         
                         4.   Each Lender will have the right to assign all or 
                         part of its interest in the Credit Facility at its
                         discretion, subject to Borrower's consent which shall
                         not be unreasonably withheld or required if an Event of
                         Default exists, provided that the amount of each such
                         assignment is not less than $10,000,000.  A processing
                         fee in the amount of $2,500 shall be due and payable to
                         Agent upon any assignment of all or part of any
                         Lender's interest in the Credit Facility.  In addition,
                         each Lender shall have the right to sell participations
                         in its interest in the Credit Facility, provided that
                         the amount thereof shall be at least $1,000,000 and
                         that no participant shall have the right to (i)
                         participate in setting the Borrowing Base or (ii)
                         approve any amendment to or waiver of the loan
                         documents except for material changes in the amount and
                         term of the Credit Facility.
                         
                         5.   Agent and Lenders shall have the right to disclose
                         any and all information they have concerning Borrower, 
                         Subsidiaries, their properties and the Credit Facility 
                         to NCMI and any financial institution that may 
                         participate in the syndication of the Credit Facility.
                         
    




- -------------------------------------------------------------------------------
Costilla Energy, Inc.                    Page 12                    NationsBank


<PAGE>
                             CONSOLIDATION AGREEMENT


     This Agreement dated this _______ day of September, 1996, by and between:

          Costilla Energy, Inc. (the "Company") - a Delaware
          corporation;

          Costilla Energy, L.L.C. (the "LLC") - a Texas limited
          liability company;

          CSL Management Corporation ("CSL") - a Texas corporation;

          Valley Gathering Company ("Valley") - a Texas corporation;

          Cadell S. Liedtke ("Liedtke") - an individual of Midland
          County, Texas;

          Michael J. Grella ("Grella") - an individual of Midland
          County, Texas;

          Henry G. Musselman ("Musselman") - an individual of Midland
          County Texas; and

          NationsBanc Capital Corporation ("NBCC") - a Texas
          corporation.

                                 R E C I T A L S

     WHEREAS, the Company has been formed to acquire and consolidate (the
"Consolidation") the following assets or entities:

     (1)  the outstanding common stock of Valley through a cash purchase;

     (2)  the assets of CSL through a cash purchase;

     (3)  the LLC (following the redemption by the LLC of NBCC's redeemable
interests in the LLC (the "Redeemable Interest") owned by NBCC), including: (a)
the stock of the three corporate subsidiaries of the LLC, being Statewide
Minerals, Inc. ("Statewide"); Costilla Petroleum Corporation ("CPC"); and
Costilla Pipeline Corporation ("Pipeline"), all Texas corporations, and (b) the
membership interests of the LLC in two Texas limited liability companies,
Costilla Redeco Energy, L.L.C. ("Energy") and Costilla Redeco Operating, L.L.C.
("Operating") through a merger (the "Merger") of the LLC into the Company
pursuant to Part Ten of Art. 1528n V.A.T.S., and Section 264 of the Delaware
General Corporation Laws.

<PAGE>

     WHEREAS, immediately prior to the Merger, the LLC will distribute
$4,218,215 in cash to the Members of the LLC in the amounts set forth herein;

     WHEREAS, concurrently with the Consolidation, the Company will close
offerings (collectively, the "Offerings") of $100,000,000 ____% senior
subordinated notes due 2006, and 4,000,000 shares of its common stock par value
$.10 per share (the "Company Common Stock") pursuant to the Securities Act of
1933, as amended (the "Securities Act"), as described in those certain
Registration Statements on Form S-1, Registration Nos. 333-08909 and 333-08913,
respectively, (as amended at the time each becomes effective, the "Registration
Statements") of the Company, each filed with the Securities and Exchange
Commission on July 26, 1996; and

     WHEREAS, the parties hereto desire to set forth the terms and conditions of
the Consolidation and provide for certain relationships and obligations among
the parties hereto following the Effective Date (as defined herein).

     NOW, THEREFORE, in consideration of the foregoing and of the mutual
covenants set forth herein, and other good and valuable consideration, the
receipt and sufficiency of which are hereby acknowledged, and intending to be
legally bound hereby, the aforesaid parties hereby agree as follows:

I.   REDEMPTION, DISTRIBUTIONS AND ACQUISITIONS

     A.   REDEMPTION OF REDEEMABLE INTERESTS OF NBCC

          1.   Immediately prior to the Merger, NBCC shall convey, transfer,
assign and sell to the LLC its Redeemable Interest for $15,486,914 (the
"Redemption") payable in cash.  The source of the cash payment required by this
Section I.A.1. shall be an advance to the LLC by the Company from the net
proceeds from the Offerings.

          2.   The Redemption shall be accomplished pursuant to an Assignment of
NBCC's Redeemable Interest substantially in the form attached hereto as Exhibit
"A" (the "Assignment").


                                       2


<PAGE>

          3.   NBCC represents that 

               (a)  the Redeemable Interest is free and clear of all
encumbrances, security interests and liens and are subject only to those
obligations arising from its membership in the LLC, as defined in the LLC's
Regulations.  

               (b)  NBCC will, upon execution of the Assignment, convey good and
indefeasible title to the Redeemable Interests as well as all rights to profits
and capital in respect thereof.

               (c)  NBCC further represents that it has taken all required
corporate action to convey the Redeemable Interests and has acquired all
necessary consents and approvals to consummate the Assignment.  No notice to or
approval by any other person, firm, entity (including governmental authorities),
is required by NBCC to execute and deliver the Assignment.

     B.   CASH DISTRIBUTION TO MEMBERS

          Immediately prior to the Merger, the LLC shall make a cash
distribution to each of its Members as follows:

                    NBCC           $  759,279
                    Liedtke        $1,936,669
                    Grella         $1,051,244
                    Musselman      $  471,023

     The source of the cash payment required by this Section I.B. shall be an
advance to the LLC by the Company from the net proceeds from the Offerings.

     C.   PURCHASE OF VALLEY STOCK

          1.   At the Closing and concurrently with the consummation of the
other transactions contemplated by the Consolidation, the Company shall purchase
all of the issued and outstanding shares of common stock of Valley from each of
Liedtke, Grella and Musselman (collectively, the "Selling Shareholders") for the
cash consideration of $660 per share ($660,000, in the aggregate) as follows:

         Selling Shareholder      No. of Shares       Cash Payment Price
         -------------------      -------------       ------------------
         Liedtke                       540                 $356,400
         Grella                        317                 $204,220
         Musselman                     143                 $ 94,380


                                       3

<PAGE>

          2.   Valley and the Selling Shareholders represent, jointly and
severally, that:

               a.   Valley is a corporation duly organized, validly existing and
in good standing under the laws of the State of Texas.  Valley has all requisite
power and authority to own, operate and carry on its business as now being
conducted.  Valley's capitalization consists of 1,000,000 shares of common
stock, par value $1.00 per share (the "Valley Common Stock"), of which 1,000
shares are issued and outstanding.  There are no other classes of stock
authorized or outstanding.  The issued and outstanding shares of Valley Common
Stock have been validly issued, and are fully paid and non-assessable.  There
are no outstanding options, warrants or similar rights to purchase or convert
any obligation into Valley Common Stock or other securities of Valley.

               b.   Valley has good and marketable title to all of its assets
and properties, tangible and intangible, that are material to Valley's business
and future prospects.  All of Valley's assets are free and clear of all
mortgages, liens, pledges, security interests, encumbrances, equities, claims,
easements, covenants, conditions and restrictions, except as set forth in the
financial statements previously delivered to the Company.

               c.   The Valley Common Stock is owned by each of the Selling
Shareholders free and clear of all liens, security interests or encumbrances. 
Each of the Selling Shareholders has all requisite authority to sell, convey and
assign such shares of Valley Common Stock without the consent of any other
person, firm, agency or other entity, other than such consents as have been
obtained.

               d.   The financial statements of Valley previously delivered to
the Company (i) present fairly the financial position of Valley as at the date
indicated and the results of its operations for the periods specified and (ii)
have been prepared in conformity with generally accepted accounting principles
applied on a consistent basis during the periods involved, except as indicated
therein, for the absence of footnotes and for closing adjustments which would
not be material in amount.  Since the date of such financial statements there
has been no material adverse change in Valley.


                                       4

<PAGE>

          3.   The sale and assignment of the Valley Common Stock shall be
effectuated by the delivery, at Closing, by each of the Selling Shareholders to
the Company, of the original common stock certificates endorsed in blank.

     D.   PURCHASE OF CSL ASSETS

          1.   At the Closing and concurrently with the consummation of the
other transactions contemplated by the Consolidation, the Company shall purchase
all of the assets of CSL for $40,000 payable in cash to CSL.  The source of the
cash payment required by this Section I.D.1. shall be net proceeds from the
Offerings.

          2.   CSL and the Selling Shareholders represent, jointly and severally
that:

               a.   CSL is a corporation duly organized, validly existing and in
good standing under the laws of the State of Texas.  CSL has all requisite power
and authority to own, operate and carry on its business as now being conducted.

               b.   CSL is the sole owner of the assets conveyed hereunder and
has full power and authority to dispose of its assets.  CSL has good and
marketable title to all of its assets and properties, tangible and intangible,
that are material to CSL's business and future prospects.  All of CSL's assets
are free and clear of all mortgages, liens, pledges, security interests,
encumbrances, equities, claims, easements, covenants, conditions and
restrictions, except as set forth in the financial statements previously
delivered to the Company.

               c.   The financial statements of CSL previously delivered to the
Company (i) present fairly the financial position of CSL as at the date
indicated and the results of its operations for the periods specified and (ii)
have been prepared in conformity with generally accepted accounting principles
applied on a consistent basis during the periods involved, except as indicated
therein, for the absence of footnotes and for closing adjustments which would
not be material in amount.  Since the date of such financial statements there
has been no material adverse change in CSL.


                                       5

<PAGE>

          3.   This conveyance shall be accomplished by the execution, by a duly
authorized officer of CSL, of a bill of sale and assignment substantially in the
form attached hereto as Exhibit "B" with a complete description of the assets
conveyed attached thereto, including the assets identified on the attachment to
Exhibit "B".  CSL shall also deliver a certified copy of Directors' and
Shareholders' Resolutions authorizing the sale of all its assets.

II.  THE SECTION 351 TRANSACTIONS

     At the Closing and concurrently with the other transactions contemplated by
the Consolidation, there shall be consummated two transactions pursuant to
Section 351 of the Internal Revenue Code of 1986, as amended (the "Code") as
follows:

     A.   THE MERGER OF LLC INTO THE COMPANY

          1.   ACTIONS TO BE TAKEN.  As a part of the Consolidation, the
following actions shall be taken by the LLC and the Company:

               a.   Simultaneous with the execution of this Agreement, the
Company and the LLC shall adopt and enter into a Plan and Agreement of Merger
(the "Merger Agreement"), a copy of which is attached hereto as Exhibit "C",
providing for the Merger of the LLC with and into the Company effective on the
Effective Date.  For the purposes of this Agreement, the "Effective Date" shall
be the date appropriate certificates of merger are filed with the secretaries of
the States of Texas and Delaware, which date shall be the same date as the date
of Closing, and the "Effective Time" shall be the time the later of such filings
is made on the Effective Date.  For tax purposes, the Merger will be treated as
a contribution of the LLC's assets and liabilities to the Company solely in
exchange for Company Common Stock pursuant to Section 351 of the Code, and a
distribution of the Company Common Stock from the Company to the former Members
of the LLC.

               b.   At the Effective Time the LLC shall be merged with and into
the Company in accordance with the terms and conditions of the Merger Agreement
and Section 351 of the Code; and the separate existence of the LLC shall cease
and the Company shall continue as the surviving entity.  The 


                                       6

<PAGE>

Company and the LLC will cause the Merger to be consummated by filing a 
Certificate of Merger (the "Merger Certificate") with the secretary of the 
States of Texas and Delaware as required by the Delaware General Corporation 
Laws and the Texas Limited Liability Company Act.

               c.   At the Effective Time, by virtue of the Merger and without
any action on the part of any person, the membership interests in the LLC, all
of which are owned by Liedtke, Grella, Musselman and NBCC, shall be converted
into and shall become the number of shares of Common Stock of the Company
determined pursuant to the Merger Agreement and Section II.A.1.e. below.  From
and after the Effective Time, the Company shall possess all of the rights,
privileges and powers of the LLC; all property, rights, privileges, powers and
other interests of the LLC shall be thereafter as effectively the property of
the Company as they were of the LLC; the title to any and all real or personal
property or other interest vested by deed or otherwise in LLC shall vest in the
Company and shall not revert or be in any way impaired by reason of the Merger;
and all rights of creditors and all liens upon any property of the LLC shall be
preserved unimpaired, and all debts, liabilities and duties of the LLC shall
thereafter attach to the Company, and may be enforced against it to the same
extent as if such debts, liabilities and duties had been contracted by it.

               d.   On and after the Effective Time by virtue of the Merger and
without any further action, the Company shall become the owner of all issued and
outstanding shares of Statewide, CPC and Pipeline, and shall become a member in
Energy and Operating.

               e.   Pursuant to the Merger, at the Closing, the Company shall
issue an aggregate of 6,000,000 shares of Company Common Stock to the holders of
the membership interests in the LLC (the "LLC Members") as follows and all
previously issued shares of the Company's Common Stock, if any, in connection
with its organization shall be cancelled:

         LLC Member          No. of Shares of Common Stock to be Issued
         ----------          ------------------------------------------
         Liedtke                               2,656,796
         Grella                                1,558,161
         Musselman                               705,035
         NBCC                                  1,080,008


                                       7

<PAGE>

          Upon the issuance of such shares of Common Stock, they shall be
validly issued, fully paid and nonassessable.  Such number of shares may be
adjusted prior to the Effective Time by an agreement executed by all of the
members, subject to consent of the representatives of the underwriters in the
Offerings.

          2.   Representations and Warranties of the LLC and the LLC Members. 
The LLC and the LLC Members, jointly and severally, represent that:  

               a.   The LLC is a limited liability company, duly organized,
validly existing and in good standing under the laws of the State of Texas.  The
LLC has all requisite power and authority (including all licenses, franchises,
permits and other governmental authorizations as are legally required) to carry
on its business as now being conducted, to own, lease and operate its properties
and assets, and to enter into and carry out its obligations under this
Agreement.  The LLC is qualified to do business in all states other than the
State of Texas wherein such qualification is required, except when the failure
to be so qualified does not have a material adverse effect on the financial
condition or results of operation of the LLC.  The LLC has taken all action
necessary to authorize the execution, delivery and performance of this Agreement
and the other agreements and documents contemplated hereby to which it is a
party.  

               b.   This Agreement has been, and the other agreements and
documents contemplated hereby have been or at Closing will be, duly executed by
the LLC and each constitutes the legal, valid and binding obligation of the LLC,
enforceable in accordance with its respective terms and conditions, except as
enforceability may be limited by bankruptcy, conservatorship, insolvency,
moratorium, reorganization, receivership or similar laws and judicial decisions
affecting the rights of creditors generally and by general principals of equity.
The LLC has full power and authority to execute, deliver and perform this
Agreement which will not violate any requirement of law or its articles of
association, regulations or other organizational documents, nor will it violate
any applicable law, regulation or order of any governmental authority nor any
agreement, indenture, mortgage, deed of trust, voting 


                                       8

<PAGE>

agreement, loan agreement, note agreement or other evidence of indebtedness, 
lease, contract or other instrument to which it is a party or by which its 
property is bound.  

               c.   The LLC has good and defensible title to its assets to be
vested in the Company pursuant to the Merger except for:

                    i.   undeveloped oil and gas leases;

                    ii.  personal property and equipment located on property
subject to oil and gas leases and used in connection with the operation and
development of oil and gas leases; and

                    iii. defects which collectively would not have a material
adverse effect on the business, properties, business prospects, condition
(financial or otherwise) or results of operation of the Company.

          For purposes of this Agreement, good and defensible title shall mean
title that is free from defects as would cause a reasonable doubt in the mind of
a reasonable and prudent purchaser in the area where the property interest is
situated and cause him, if he were purchasing such interest, to refuse to accept
the same at its full agreed value.  The title to certain assets may be subject
to drilling obligations in leases, farmout agreements, operating agreements, gas
purchase contracts, covenants, restrictions, rights, easements, liens and
encumbrances which are valid and in full force and effect as to such properties,
and minor irregularities in title which, collectively, do not interfere with the
operation, use and enjoyment of any such asset in the normal course of business
as presently conducted by the LLC or materially impair the value thereof for
such business.  

               d.   The LLC's assets (except for undeveloped oil and gas leases
and personal property and equipment located on property subject to oil and gas
leases and used in connection with the operation and development of oil and gas
leases) are held by the LLC free and clear of any security interests, mortgages,
pledges, liens, encumbrances, charges, defects or restrictions of any kind or
character other than (i) those described in the preceding paragraph c and; (ii)
those granted to NationsBridge, L.L.C. and its affiliates pursuant to security
agreements, mortgages, assignments and other instruments to secure 


                                       9

<PAGE>

the obligation of the LLC under various loan arrangements.  The oil and gas 
interests of the LLC were acquired in a manner customary in the oil and gas 
industry using reasonable diligence used by prudent purchasers in the area, 
and the developed portion of the oil and gas leases are valid, subsisting and 
enforceable against each of the parties thereof and are in full force and 
effect in accordance with their respective terms (except for such leases that 
have partially terminated as to certain nonproducing lands and/or depths 
pursuant to the terms thereto) and where the failure of such leases to be 
enforceable or to be in full force and effect would not, in either instance, 
have a material adverse effect on the LLC or its business, properties, 
business prospects, conditions (financial or otherwise) or results of 
operations, taken as a whole. 

               e.   There are no actions, suits or proceedings pending or
threatened against or affecting the LLC, or its officers, directors or members
in their capacities as such, before any federal, state or local body or
authority, domestic or foreign, wherein an unfavorable ruling, decision or
finding would have a material adverse effect on its business, properties,
business prospects, conditions (financial or otherwise) or results of
operations.

     B.   THE PUBLIC OFFERING  

     Concurrently with the other transactions contemplated by the Consolidation,
and as a condition precedent thereto, the Company shall have closed an initial
public offering (the "Common Stock Offering") of shares of the Company Common
Stock pursuant to the Securities Act, as described in that certain Registration
Statement on Form S-1, Registration No. 333-08913 filed with the Securities and
Exchange Commission.  Proceeds from the Common Stock Offering shall constitute
"property" contributed to the Company solely in exchange for common stock as
defined in  Code Section 351 and shall be the result of an "underwriting" as
described in the Regulations to the Code at Section 1.351-1(a)(3).


                                      10

<PAGE>

III. REPRESENTATIONS AND WARRANTIES OF THE COMPANY

     In connection with transactions contemplated under Article I and II hereof,
the Company represents to each of the LLC, Valley, CSL, Liedtke, Grella,
Musselman and NBCC that the following representations and warranties are true
and correct as of the closing:

     A.   The Company is a corporation duly organized and validly existing, in
good standing, under the laws of the State of Delaware, with all requisite
corporate power and authority to own and to lease its property and to carry on
its business as now conducted, and is duly qualified and authorized to do
business as a foreign corporation and is in good standing in each jurisdiction
wherein the failure to be so qualified and authorized would have a material
adverse effect on the financial condition or results of operations of the
Company.

     B.   It has full requisite corporate and other power and authority to enter
into this Agreement and to perform its obligations hereunder.  The execution and
delivery of this Agreement by the Company and the consummation by the Company of
the transactions contemplated hereby have been duly authorized by the Board of
Directors of the Company and no other corporate proceeding on the part of the
Company is necessary for the execution and delivery of this Agreement by it. 
This Agreement has been duly executed and delivered by the Company and
constitutes a legal, valid and binding obligation of the Company, enforceable
against it in accordance with its terms.

IV.  REGISTRATION RIGHTS

     A.   INCIDENTAL REGISTRATION.  

          1.  REQUEST FOR REGISTRATION.  If at any time the Company proposes to
file a registration statement under the Securities Act (other than a
registration statement on Form S-4 or Form S-8 or other similar forms providing
for the registration of employee benefits plans) with respect to an offering of
shares of Company Common Stock (the "Shares") for its own account or for the
account of any of Liedtke, Grella, Musselman or NBCC (collectively, the
"Affiliated Holders") (including, without limitation, a "Demand Registration"
pursuant to Section IV.B.), then the Company shall give written notice of such



                                     11


<PAGE>

proposed filing and its distribution plan to each Affiliated Holder owning more
than five percent (5%) of the total outstanding Company Common Stock (each, an
"Eligible Holder") as soon as practicable (but in no event less than twenty (20)
days before the anticipated filing date of such registration statement).  Such
notice shall offer each Eligible Holder the opportunity to have all or any part
of the Shares owned by such Eligible Holder included in the registration
statement proposed to be filed by the Company, and thereby be registered under
the Securities Act (and any related qualification under any applicable state
securities or "blue sky" laws or other compliance) or, at the Company's option,
in a separate registration statement to be filed concurrently with such
registration statement (in either case, "Incidental Registration"). Within
fifteen (15) days after receiving such notice, each Eligible Holder may make a
written request to the Company that any or all of the Eligible Holder's Shares
be included in the Incidental Registration, which notice shall specify the
precise portion of such Eligible Holder's Shares to be so included. Subject to
the provisions of Section IV.A.2., the Company shall include in the Incidental
Registration all Shares in the Company with respect to which the Company has
received such a written request by an Eligible Holder.  Any Eligible Holder
shall be permitted to withdraw all or part of his Shares in the Company from an
Incidental Registration at any time prior to the effective date of the
registration statement filed with respect to such Incidental Registration.

          2.   PRIORITY ON INCIDENTAL REGISTRATION.  The Company shall use its
best efforts to cause the managing underwriter or underwriters of a proposed
underwritten offering by the Company, in connection with which Incidental
Registration is requested, to permit the inclusion of all Shares in the Company
requested by the Eligible Holders (the "Selling Incidental Holders") to be
included in the Incidental Registration on the same terms and conditions as
similar securities of the Company included therein to the extent appropriate.
Notwithstanding the foregoing, if the managing underwriter or underwriters of
such offering deliver a written opinion to the Company that, because of the size
of the offering which the Selling Incidental Holders, the Company and any other
security holders of the Company intend to make, the success of the offering
would be materially and adversely affected by inclusion of more than a specific



                                     12


<PAGE>

number of the Shares requested to be so included, then such registration shall
be comprised of the following Shares:

               a.   PRIMARY REGISTRATION.  If such Incidental
          Registration is incident to a primary registration on behalf
          of the Company, then the Shares to be included in such
          primary registration shall be as follows:

                    (i)   first, the Shares intended to be offered by the
               Company;

                    (ii)  second, the Shares owned and requested to be
                          registered by NBCC; and

                    (iii) third, the Shares owned, and requested to be
                          registered, by the other Selling Incidental
                          Holders in proportion to the ratio that the
                          number of Shares owned by each such remaining
                          Selling Incidental Holder (excluding any
                          Shares to be registered pursuant to
                          subparagraph IV.A.2(a)(ii)) bears to the
                          total number of Shares owned by all such
                          Selling Incidental Members (excluding any
                          Shares to be registered pursuant to
                          subparagraph IV.A.2.(a)(ii)) (or as otherwise
                          agreed); and

                    b.   SECONDARY REGISTRATIONS.  If such Incidental
               Registration is incident to a secondary registration on behalf of
               Affiliated Holders owning Shares (including, a Demand
               Registration under Section IV.B.), then the total number of
               Shares to be included in such secondary registration (the
               "Available Shares") shall be allocated as follows: (i) up to 50%
               to Shares owned, and requested to be registered by, NBCC; and
               (ii) the remainder (to the extent not requested to be registered
               by NBCC) to all other Selling Incidental Holders requesting the
               Company to have their Shares included in such registration, with
               such remaining 




                                     13


<PAGE>

               Available Shares being allocated among such other Selling 
               Incidental Holders in proportion to the total number of Shares
               owned by each such other Selling Incidental Holder bears to
               the total number of Shares owned by all such other Selling
               Incidental Holders.

        3.     ASSIGNMENTS, ETC..  All rights under this Section IV.A.
     shall be freely assignable and such rights are not intended to create
     rights in any person not a party to this Agreement or its assigns.

     B.   DEMAND REGISTRATION.

          1.   REQUEST FOR REGISTRATION.  NBCC may make written requests for
registration under the Securities Act ("Demand Registration") of all or part of
NBCC's Shares, subject to the conditions of this Article IV.  Each such request
shall specify the precise number of Shares proposed to be sold and shall also
specify the intended method of disposition thereof. Upon receiving a request for
a Demand Registration, the Company shall give written notice of such request to
all other Eligible Holders at least twenty (20) days before the anticipated
filing date of such registration statement, and each such Eligible Holder shall
be entitled to participate in such Demand Registration as a Selling Incidental
Holder pursuant to the terms, conditions and limitations set forth in Section
IV.A.  As soon as practicable after receipt of a request for a Demand
Registration, the Company shall file a registration statement on an appropriate
form under the Securities Act for the number of Shares requested by NBCC and any
Selling Incidental Holders, subject to the conditions of this Article IV.

          2.   LIMITATION ON DEMAND REGISTRATION.  No Demand Registration may be
requested by NBCC at any time during which a registration statement filed by the
Company in which NBCC was entitled to participate is effective under the
Securities Act (or would have been entitled but for the delivery by the managing
underwriter or underwriters of the opinion set forth in the second sentence of
Section IV.A.2.) or within ninety (90) days after the closing of any offering
effected pursuant to any such registration statement.  Notwithstanding anything
to the contrary in this Article IV, the Company shall not 



                                     14


<PAGE>

be obligated to effect more than two Demand Registrations for NBCC.  A 
registration shall not count as a Demand Registration: (a) unless a 
registration statement with respect thereto has become effective; (b) if, 
after such registration statement has become effective, such registration is 
interfered with by any stop order, injunction or other order or requirement 
of the Securities and Exchange Commission ("SEC") or other governmental 
agency or court for any reason not attributable to NBCC, and such 
registration statement has not thereafter again become effective; or (c) if 
the conditions to closing specified in the underwriting agreement, if any, 
entered into in connection with such registration are not satisfied or 
waived, other than by reason of a failure on the part of NBCC.

          3.   EFFECTIVE REGISTRATION AND EXPENSES. The Company shall use its
reasonable best efforts to cause each registration statement filed pursuant to a
Demand Registration to become effective under the Securities Act and thereafter
to keep it effective under the Securities Act for a period of ninety (90) days
(subject to extension pursuant to the last paragraph of Section IV.D. hereof). 
The Company shall pay all Registration Expenses (as defined in Section IV.E.17)
in connection with any Demand Registration, whether or not it becomes effective,
except (a) as provided in Section IV.E. or (b) if such Demand Registration is
expected to become effective within the price range estimated by the underwriter
but is withdrawn due to the decision of NBCC.

          4.   SELECTION OF UNDERWRITERS.  If NBCC so elects, the offering
pursuant to such Demand Registration shall be in the form of an underwritten
offering. If any Demand Registration is in the form of an underwritten offering,
the Company shall select and obtain the investment banker or investment bankers
and manager or managers that will administer the offering, subject to the
approval of NBCC (which approval shall not be unreasonably withheld).

     D.   HOLDBACK AGREEMENTS.

          1.   RESTRICTIONS ON PUBLIC SALE BY ELIGIBLE HOLDERS.  Upon the offer
by the Company to include any Affiliated Holders' Shares ("Selling Holders") in
a registration statement filed pursuant to an Incidental Registration or a
Demand Registration (or in case the Company files a registration statement 



                                     15


<PAGE>

for Common Stock and the managing underwriters deliver the opinion set forth 
in the second sentence of Section IV.A.2.), each Eligible Holder agrees not 
to effect any public sale or distribution of the same type of securities 
being registered or a similar security of the Company or any securities 
convertible into or exchangeable or exercisable for such securities, including
a sale pursuant to Rule 144 under the Securities Act, during the fourteen (14)
days prior to, and during a 90-day period beginning on, the effective date of 
such registration statement (except as part of such registration), if and to 
the extent requested by the Company in the case of a non-underwritten public 
offering or if and to the extent requested by the managing underwriter or 
underwriters in the case of an underwritten public offering.

          2.   RESTRICTIONS ON PUBLIC SALE BY THE COMPANY. The Company agrees
that during the fourteen (14) days prior to, and during a 180-day period
beginning on, the effective date of any registration statement filed pursuant to
a Demand Registration, it shall not effect any public or private sale or
distribution of the same type of securities being registered or a similar
security of the Company, or any securities convertible into or exchangeable or
exercisable for securities of the nature of such securities (except as part of
such registration or pursuant to a registration statement on Form S-4 or S-8 or
other similar forms providing for the registration of employee benefits plans).

     E.   REGISTRATION PROCEDURES.    Subject to the other provisions and
limitations contained in this Article IV, whenever any Eligible Holder has
requested that any of its Shares be registered pursuant to an Incidental
Registration or whenever NBCC has requested that any of its Shares be registered
pursuant to a Demand Registration, the Company shall use its best efforts to
effect the registration and the sale of such Shares in accordance with the
intended method of disposition thereof, as soon as practicable, and in
connection with any such request, the Company shall as expeditiously as
possible:

          1.   REGISTRATION STATEMENT.  Prepare and file with the SEC a
registration statement on any form for which the Company then qualifies or which
counsel for the Company shall deem appropriate and which form shall be available
for the sale of the Selling Holders' Shares to be registered thereunder in
accordance with the intended method of distribution thereof, and use its best
efforts to cause such filed 



                                     16


<PAGE>

registration statement to become effective under the Securities Act; provided 
that: (a) in the case of an Incidental Registration, at least five (5) days 
before filing a registration statement or prospectus, or as promptly as 
practicable prior to filing any amendments or supplements thereto, the 
Company shall furnish to one (1) counsel, selected by the Selling Holders, 
copies of all such documents proposed to be filed, which documents shall be 
subject to the review of the Selling Holders and such counsel; (b) in the 
case of a Demand Registration, NBCC and one (1) counsel selected by it shall 
have the right to participate in the preparation of such documents; and (c) 
after the filing of the registration statement, the Company shall promptly 
notify each such Selling Holder and such counsel of comments received from, 
or any stop order issued or threatened by, the SEC and take all reasonable 
actions required to respond to such comments or, as the case may be, prevent 
the entry of such stop order or to remove it, if it has been entered;

          2.   AMENDMENTS AND SUPPLEMENTS TO REGISTRATION STATEMENT.  Prepare
and file with the SEC such amendments and supplements to such registration
statement and the prospectus used in connection therewith as may be necessary to
keep such registration statement effective for the applicable period required by
the terms hereof, which period shall terminate when all Shares covered by such
registration statement have been sold or, in the case of an Incidental
Registration, for such time period as the Company shall determine in its sole
discretion (but not before the expiration of the 90-day period referred to in
Section 4(3) of the Securities Act and Rule 174 thereunder, if applicable) and
comply with the provisions of the Securities Act with respect to the disposition
of all securities covered by such registration statement during such period in
accordance with the intended methods of disposition as set forth in such
registration statement;

          3.   PROPOSED REGISTRATION DOCUMENTS.  Furnish to each Selling Holder,
prior to filing the registration statement, if requested, copies of such
registration statement as proposed to be filed, and thereafter furnish to each
Selling Holder such number of copies of such registration statement, each
amendment and supplement thereto (in each case including all exhibits thereto
and documents incorporated or deemed to be incorporated therein by reference),
the prospectus included in such registration statement



                                     17


<PAGE>

(including each preliminary prospectus), and such other documents as each 
Selling Holder may reasonably request in order to facilitate the disposition 
of the Shares owned by each Selling Holder;

          4.   BLUE SKY QUALIFICATION.  Use its best efforts to register or
qualify such Shares under such other securities or blue sky laws of such
jurisdictions as each Selling Holder reasonably (in light of each Selling
Holder's intended plan of distribution) requests and do any and all other acts
and things which may be reasonably necessary to enable each Selling Holder to
consummate the disposition in such jurisdictions of the Shares owned by each
Selling Holder and keep each such registration or qualification (or exemption
therefrom) effective during the period such registration statement is effective;
provided that the Company shall not be required to: (a) qualify generally to do
business in any jurisdiction where it would not otherwise be required to qualify
but for this subsection; (b) subject itself to taxation in any such
jurisdiction; or (c) consent to general service of process in any such
jurisdiction;

          5.   APPROVAL BY OTHER GOVERNMENTAL AUTHORITIES.  Use its best efforts
to cause such Shares to be registered with or approved by such other
governmental agencies or authorities as may be necessary by virtue of the
business and operations of the Company to enable each Selling Holder to
consummate the disposition of such Shares, provided that the Company shall not
be required to: (a) qualify generally to do business in any jurisdiction where
it would not otherwise be required to qualify, but for this subsection; (b)
subject itself to taxation in any such jurisdiction; or (c) consent to general
service of process in any such jurisdiction;

          6.   NOTICE; AMENDMENT OF PROSPECTUS.  At any time when a prospectus
relating to Shares is required to be delivered under the Securities Act: (a)
notify each Selling Holder of the occurrence of an event requiring the
preparation of a supplement or amendment to such prospectus; (b) prepare and
file such supplement, amendment or any other required document, so that as
thereafter delivered to the purchasers of such Shares, such prospectus shall not
contain an untrue statement of a material fact or omit to state any material
fact required to be stated therein or necessary to make the statements therein
not 



                                     18


<PAGE>

misleading; and (c) promptly make available to each Selling Holder any such
supplement, amendment or other document;

          7.   EXECUTION OF CUSTOMARY AGREEMENTS; FURTHER ACTION.  Enter into
and perform customary agreements (including an underwriting agreement in
customary form with the managing underwriter or underwriters, if any), use its
best efforts to obtain any necessary consents in connection with any proposed
registration and sale of Shares, and take such other actions as are reasonably
required in order to expedite or facilitate the disposition of such Shares;

          8.   INSPECTION AND AVAILABILITY OF RECORDS.  Make available for
inspection by each Selling Holder, any underwriter participating in any
disposition pursuant to such registration statement, and any attorney,
accountant, or other professional retained by any Selling Holder or such
underwriter (collectively, the "Inspectors"), all financial and other records,
pertinent corporate documents, and properties of the Company (collectively, the
"Records") as shall be reasonably necessary to enable them to exercise their due
diligence responsibility, and cause the Company's Officers and employees to
supply all information reasonably requested by any such Inspectors in connection
with such registration statement; provided, however, records which the Company
determines, in good faith, to be confidential and which it notifies the
Inspectors are confidential shall not be disclosed by the Inspectors unless: (a)
in the reasonable judgment of counsel to the Company, the disclosure of such
Records is necessary to avoid or correct a misstatement or omission in such
registration statement or (b) the release of such Records is ordered pursuant to
a subpoena or other order from a court of competent jurisdiction; with each
Selling Holder hereby agreeing that information obtained by him, or on his
behalf, as a result of such inspections shall be deemed confidential and shall
not be used by him as the basis for any market transactions in the securities of
the Company unless and until such is made generally available to the public; and
each Selling Holder hereby further agrees that he shall, upon learning that
disclosure by such Selling Holder of such Records is sought in a court of
competent jurisdiction, give prompt notice to the Company and allow the 



                                     19


<PAGE>

Company, at the Company's expense, to undertake appropriate action to prevent 
disclosure of the Records deemed confidential;

          9.   COMFORT LETTER.  If such sale is pursuant to an underwritten
offering, use its best efforts to obtain a comfort letter or comfort letters
from the Company's independent public accountants in customary form and covering
such matters of the type customarily covered by comfort letters as any Selling
Holder or the managing underwriter or underwriters reasonably request;

          10.  OTHER COMPLIANCE; EARNINGS STATEMENT.  Otherwise use its best
efforts to comply with all applicable rules and regulations of the SEC, and make
available to its security holders as soon as reasonably practicable, an earnings
statement covering a period of twelve (12) months, beginning within three (3)
months after the effective date of the registration statement, which earnings
statement shall satisfy the provisions of Section 11(a) of the Securities Act;

          11.  PROSPECTUS SUPPLEMENT; POST-EFFECTIVE AMENDMENT.  If requested by
the managing underwriter or underwriters, if any, or any Selling Holder in
connection with an underwritten offering pursuant to an Incidental Registration
or a Demand Registration: (i) promptly incorporate in a prospectus supplement or
post-effective amendment such information as the managing underwriter or
underwriters, if any, and/or any Selling Holder reasonably requests to be
included therein, as may be required by applicable laws; and (ii) make all
required filings of such prospectus supplement or such post-effective amendment
as soon as practicable after the Company has received notification of the
matters to be incorporated in such prospectus supplement or post-effective
amendment; provided, however, that the Company shall not be required to take any
action pursuant to this Section IV.E.11. that is not, in the reasonable opinion
of counsel for the Company, in compliance with applicable law;

          12.  REMOVAL OF SUSPENSIONS.  Use its reasonable efforts to obtain the
withdrawal of any order suspending the effectiveness of a registration statement
filed in connection herewith, or the lifting of any suspension of the
qualification (or exemption from qualification) of any of the Shares for sale in
any jurisdiction, at the earliest possible moment;




                                     20


<PAGE>

          13.  SHARE CERTIFICATES.  Cooperate with each Selling Holder and the
managing underwriters, if any, to facilitate the timely preparation and delivery
of certificates, if any, representing Shares to be sold, which certificates or
notes shall not bear any restrictive legends and shall be in a form eligible for
deposit with The Depository Trust Company or other appropriate depository; and
enable such certificates representing Shares to be in such denominations and
registered in such names as the managing underwriters, if any, or holders may
request at least two (2) Business Days prior to any sale of Shares;

          14.  SECURITIES EXCHANGE LISTING.  Cause all such Shares to be listed
on any securities exchange (or on The Nasdaq Stock Market's National Market) on
which similar securities issued by the Company are then listed or traded;
provided, that the applicable listing requirements are satisfied in the opinion
of the Company and its counsel;

          15.  LEGAL OPINION.  Furnish, at the request of any Selling Holder on
the date such securities are delivered to the underwriters for sale pursuant to
such registration or, if such securities are not being sold through
underwriters, on the date the registration statement with respect to such
securities becomes effective, an opinion, dated such date, of counsel
representing the Company for the purposes of such registration, addressed to the
underwriters, if any, and to the Selling Holder making such request, covering
such legal matters with respect to the registration in respect of which such
opinion is being given as such Selling Holder or underwriters may reasonably
request and as are customarily included in such opinions; and

          16.  FURTHER ACTION.  Take such other actions as are reasonably
required in order to expedite or facilitate the disposition of such Shares.

          Notwithstanding the provisions of this Section IV, the Company shall
be entitled to postpone, for a reasonable period of time, the filing of any
registration statement under an Incidental Registration if the Company
determines, in the good faith exercise of its reasonable business judgment, that
such registration and offering could materially interfere with any bona fide
financing, acquisition, or other material business plans of the Company
(including a proposed primary offering by the Company of its own 

                                      21 
<PAGE>

securities) or would require disclosure of non-public information, the 
premature disclosure of which could materially adversely affect the business, 
properties, operations or financial results of the Company; provided, 
however, that the Company shall not be required to disclose to the Selling 
Incidental Holders any such transaction, plan or non-public information.  If 
the Company postpones the filing of a registration statement pursuant hereto, 
it shall promptly notify in writing the Selling Incidental Holders when the 
events or circumstances permitting such postponement have ended and at such 
time shall proceed with the filing of the registration statement as 
requested.  If the Company shall postpone the filing of a registration 
statement pursuant hereto, then the Selling Incidental Holders shall have the 
right to withdraw their request for registration by giving written notice to 
the Company at any time within five (5) days after the date the Company 
notifies such Selling Incidental Holders of its willingness to proceed with 
the filing of the registration statement.  The Company may require each 
Selling Holder to furnish promptly in writing to the Company such information 
regarding the distribution of the Shares as the Company may from time to time 
reasonably request and such other information as may be legally required in 
connection with such registration.

          Each Selling Holder shall cooperate with the Company and, if
applicable, the underwriter or underwriters in providing such information and
executing and delivering such documents as the Company or the underwriter or
underwriters reasonably shall request in connection with any such registration,
and the Company shall not be obligated to include in any such registration any
Shares of any Eligible Holder who does not comply with this paragraph.

          Each Selling Holder agrees that, upon receipt of any notice from the
Company of the happening of any event of the kind described in Section IV.E.6.,
such Selling Holder shall forthwith discontinue disposition of Shares pursuant
to the registration statement covering such Shares, until such Selling Holder's
receipt of the copies of the supplemented or amended prospectus contemplated by
Section IV.E.6. and, if so directed by the Company, such Selling Holder shall
deliver to the Company all copies, other than permanent file copies then in such
Selling Holder's possession, of the most recent prospectus 

                                      22 
<PAGE>

covering such Shares at the time of receipt of such notice. If the Company 
shall give such notice, the Company shall extend the period during which such 
registration statement shall be maintained effective (including the period 
referred to in Section IV.E.2.) by the number of days during the period from 
and including the date of the giving of notice pursuant to Section IV.E.6. 
hereof to the date when the Company shall make available to such Selling 
Holder a prospectus supplemented or amended to conform with the requirements 
or Section IV.E.6.

          17.  REGISTRATION EXPENSES. In connection with any registration
statement required to be filed under this Article IV, the Company shall pay the
following registration expenses (the "Registration Expenses"): (a) all
registration and filing fees; (b) fees and expenses relating to compliance with
securities or blue sky laws (including reasonable fees and disbursements of
counsel in connection with blue sky qualifications of the Shares requested to be
registered); (c) printing expenses (including expenses of printing certificates,
if any, for Shares requested to be registered); (d) internal expenses
(including, without limitation, all salaries and expenses of its Officers and
employees performing legal or accounting duties); (e) any fees and expenses
incurred in connection with the listing of the Shares requested to be registered
on any national securities exchange or automated quotation system on which the
Company's Shares are listed; (f) reasonable fees and disbursements of counsel
for the Company and customary fees and expenses for independent certified public
accountants retained by the Company (including the costs associated with the
delivery by independent certified public accountants of a comfort letter or
comfort letters requested pursuant to Section IV.E.9. hereof); (g) the
reasonable fees and expenses of any special experts or other Persons retained by
the Company in connection with such registration; (h) reasonable fees and
expenses of one counsel (who shall be reasonably acceptable to the Company) for
the Selling Holders incurred in connection with any Incidental Registration
hereunder and reasonable fees and expenses of one counsel (who shall be
reasonably acceptable to the Company) for NBCC incurred in connection with any
Demand Registration hereunder; and (i) messenger, courier, delivery and
telephone expenses related to any registration contemplated hereunder.  The
Company shall not have any obligation to pay any underwriting 

                                      23 
<PAGE>

fee discounts or commissions attributable to the sale of Shares pursuant to 
any Incidental Registration or Demand Registration, or any out-of-pocket 
expenses of any Selling Holder (or the agents who manage his accounts) 
incurred in connection therewith, which amounts shall be the responsibility 
of the Selling Holder or Selling Holders.

     F.   SPECIAL PROVISIONS RELATING TO REGISTRATION RIGHTS.

          1.   ASSIGNMENT. Rights relating to Incidental Registration and Demand
Registration rights granted pursuant to this Article IV are transferable to
transferees of Shares permitted under this Agreement who execute and deliver to
the Company an Addendum to this Agreement in which such transferee agrees to be
bound by this Agreement and to observe and comply with this Agreement and with
all obligations and restrictions imposed hereby.

          2.   LIMITED DEMAND REGISTRATION RIGHTS. Except as set forth in this
Agreement, the Company has not granted to any Person the right to require the
Company to register the Shares in the Company or any other securities of the
Company.  

     G.   INDEMNIFICATION; CONTRIBUTION.

          1.   INDEMNIFICATION BY THE COMPANY. The Company agrees to indemnify
and hold harmless each Selling Holder and, if applicable, its directors and
officers and each Person who controls such Selling Holder within the meaning of
either Section 15 of the Securities Act or Section 20 of the Securities Exchange
Act of 1934, as amended (the "Exchange Act"), from and against any and all
losses, claims, damages, liabilities and expenses (including reasonable legal
and other costs of investigation and defense) (collectively, "Losses") arising
out of or based upon any untrue statement or alleged untrue statement of a
material fact contained in any such registration statement or prospectus
relating to Shares or in any amendment or supplement thereto or in any
preliminary prospectus, or arising out of or based upon any omission or alleged
omission to state therein a material fact required to be stated therein or
necessary to make the statements therein not misleading, except insofar as such
losses, claims, damages, liabilities, or expenses arise out of, or are based
upon, any such untrue statement or omission or allegation 

                                      24 
<PAGE>

thereof based upon information furnished in writing to the Company by such 
Selling Holder or on such Selling Holder's behalf for use therein.  The 
Company also agrees to indemnify any underwriters of the Shares, their 
officers and directors, and each Person who controls such underwriters within 
the meaning of either Section 15 of the Securities Act or Section 20 of the 
Exchange Act on substantially the same basis as the indemnification of 
Selling Holders provided in this Section IV.G.

          2.   INDEMNIFICATION BY SELLING HOLDERS. Each Selling Holder agrees to
indemnify and hold harmless the Company, the Affiliated Holders, its Officers,
Directors and each Person, if any, who controls the Company within the meaning
of either Section 15 of the Securities Act or Section 20 of the Exchange Act
(other than the Selling Holder) to the fullest extent lawful, from and against
all Losses arising out of or based upon any untrue or alleged untrue statement
of a material fact contained in any registration statement or prospectus
relating to the Shares of the Company or in any amendment or supplement thereto
or in any preliminary prospectus, or arising out of or based upon any omission
or alleged omission of a material fact required to be stated therein or
necessary to make the statements therein not misleading, to the extent, but only
to the extent, that such information was furnished in writing by such Selling
Holder or on such Selling Holder's behalf, in such Selling Holder's capacity as
a Selling Holder and not in his capacity as an Officer, expressly for use in any
registration statement or form of prospectus relating to the Shares or any
amendment or supplement thereto, provided, however, that (a) with respect to any
untrue statement or omission or alleged untrue statement or omission made in any
preliminary or final prospectus, the indemnity agreement contained in this
subsection shall not apply to the extent that any such Losses result from the
fact that a current copy of the prospectus was not sent or given to the Person
asserting any such Losses at or prior to the written confirmation of the sale of
the Shares concerned to such Person, if it is determined that it was the
responsibility of the Company or any other Person or entity (other than the
Selling Holder) to provide such Person with a current copy of the prospectus and
such current copy of the prospectus would have cured the defect giving rise to
such Losses and (b) no Selling Holder shall be liable for indemnity in an amount
in excess of the gross proceeds received by such Selling Holder 

                                      25 
<PAGE>

in any Incidental Registration or Demand Registration. Each Selling Holder 
also agrees to indemnify and hold harmless underwriters of the Shares, their 
officers and directors, and each Person who controls such underwriters on 
substantially the same basis as the indemnification of the Company provided 
in this Section IV.G.

          3.   CONDUCT OF INDEMNIFICATION PROCEEDINGS.  If any action or
proceeding (including any governmental investigation) shall be brought or
asserted against any Person entitled to indemnification under Section IV.G.1. or
Section IV.G.2. above ("Indemnified Party") with respect to which indemnity may
be sought from any party who has agreed to provide such indemnification
("Indemnifying Party"), the Indemnified Party shall promptly notify the
Indemnifying Party in writing, and the Indemnifying Party shall assume the
defense thereof, including the employment of counsel reasonably satisfactory to
such Indemnified Party, and shall assume the payment of all expenses relating to
such defense, including without limitation reasonable attorneys' fees. The
Indemnified Party shall have the right to employ separate counsel in any such
action and to participate in the defense thereof, but the fees and expenses of
such counsel shall be at the expense of such Indemnified Party unless: (a) the
Indemnifying Party has agreed to pay such fees and expenses; (b) the
Indemnifying Party shall have failed to promptly assume the defense of such
action or proceeding and to employ counsel reasonably satisfactory to the
indemnified Party; or (c)(i) the named parties to any such action or proceeding
(including any impleaded parties) include both such Indemnified Party and the
Indemnifying Party, and such Indemnified Party shall have been advised by
counsel that there is a conflict of interest on the part of counsel employed by
the Indemnifying Party to represent such Indemnified Party, or (ii) the
Indemnified Party's counsel shall have advised the Indemnified Party that there
may be defenses available to the Indemnified Party that are different from or in
addition to those available to the Indemnifying Party and that the Indemnifying
Party is not able to assert on behalf of or in the name of the Indemnified Party
(in which case of either of (i) or (ii), if such Indemnified Party notifies the
Indemnifying Party in writing that it elects to employ separate counsel at the
expense of the Indemnifying Party), the Indemnifying Party shall not have the
right to assume the defense of such action 

                                      26 
<PAGE>

or proceeding on behalf of such Indemnified Party; it being understood, 
however, that the Indemnifying Party shall not, in connection with any one 
such action or proceeding or separate but substantially similar or related 
actions or proceedings in the same jurisdiction arising out of the same 
general allegations or circumstances, be liable for the fees and expenses of 
more than one separate firm of attorneys (together with appropriate local 
counsel) at any time for all such Indemnified Parties, which firm shall be 
designated in writing by one or more Indemnified Parties that hold a majority 
of the Shares held by all of the Indemnified Parties. The Indemnifying Party 
shall not be liable for any settlement of any such action or proceeding 
effected without its written consent, which consent shall not be unreasonably 
withheld, but if settled with its written consent, or if there be a final 
judgment for the plaintiff in any such action or proceeding, the Indemnifying 
Party shall indemnify and hold harmless such Indemnified Parties from and 
against any loss or liability (to the extent stated above) by reason of such 
settlement or judgment.

          4.   CONTRIBUTION.  If the indemnification provided for in this
Section IV.G. is unavailable to the Indemnified Parties in respect of any Losses
(other than by reason of exceptions provided in Section IV.G.1. or Section
IV.G.2.), then each Indemnifying Party, in lieu of indemnifying such Indemnified
Party, shall contribute to the amount paid or payable by such Indemnified Party
as a result of such Losses: (a) in such proportion as is appropriate to reflect
the relative fault of the Indemnifying Party, on the one hand, and the
Indemnified Party, on the other hand, with respect to the statements or
omissions which resulted in such Losses, or action in respect thereof, as well
as any other relevant equitable considerations; or (b) if the allocation
provided by clause (a) above is not permitted by applicable law, in such
proportion as shall be appropriate to reflect the relative benefits received by
the Indemnifying Party, on the one hand, and the Indemnified Party, on the other
hand, from the offering of the securities covered by such registration
statement; provided, however, that under no circumstances shall the allocation
set forth in this clause (b) be applicable to any Losses arising out of a Demand
Registration effected at the request of NBCC. The relative fault of the
Indemnifying Party, on the one hand, and of the Indemnified Party, on the other
hand, shall be determined by reference to, among other things, whether the
untrue or alleged 

                                      27 
<PAGE>

untrue statement of a material fact or the omission or alleged omission to 
state a material fact relates to information supplied by such party, and such 
party's relative intent, knowledge, access to information, and opportunity to 
correct or prevent such statement or omission. The relative benefits received 
by the Indemnifying Party, on the one hand, and the Indemnified Party, on the 
other hand, shall be deemed to be in the same proportion as the total 
proceeds from the offering (net of underwriting discounts and commissions, 
but before deducting expenses) received by the Indemnifying Party bears to 
the total proceeds (net of underwriting discounts and commissions, but before 
deducting expenses) received by the Indemnified Party.

          The Company and each Selling Holder agree that it would not be just
and equitable if contribution pursuant to this Section IV.G.4. were determined
by pro rata allocation (even if the underwriters were treated as one entity for
such purpose) or by any other method of allocation which does not take into
account the equitable considerations referred to in the immediately preceding
paragraph.  Notwithstanding the provisions of this Section IV.G.4., no Selling
Holder shall be required to contribute any amount in excess of the amount by
which the total price at which the Shares of such Selling Holder were offered to
the public exceeds the amount of any damages which such Selling Holder has
otherwise been required to pay by reason of such untrue or alleged untrue
statement or omission or alleged omission.  No Person guilty of fraudulent
misrepresentation (within the meaning of Subsection 11(f) of the Securities Act)
shall be entitled to contribution from any Person who was not guilty of such
fraudulent misrepresentation.

          5.   SURVIVAL. The indemnity and contribution agreements contained in
this Section IV.G. shall remain operative and in full force and effect
regardless of: (a) any amendment, restatement or termination of this Agreement
or any underwriting agreement; (b) any investigation made by or on behalf of any
Indemnified Party or by or on behalf of the Company; and (c) the consummation of
the sale or successive resale of the Shares, until the expiration of all periods
during which any suit or proceeding of the type for which indemnity may be
claimed under this Section IV.G. ("Indemnifiable Claims") have 

                                      28 
<PAGE>

elapsed, and thereafter until the final and non-appealable resolution of any 
and all Indemnifiable Claims commenced during such periods and the final 
resolution between the Company and any Selling Holder of any and all claims 
made by either party under this Section IV.G. hereof with respect to those 
Indemnifiable Claims.

     G.   Participation in Underwritten Registrations. No Selling Holder may
participate in any underwritten registration hereunder unless such Selling
Holder: (a) agrees to sell his Shares on the basis provided in any underwriting
arrangements approved by the Persons or entities entitled hereunder to approve
such arrangements; and (b) completes and executes all questionnaires, powers of
attorney, indemnities, underwriting agreements, and other documents reasonably
required under the terms of such underwriting arrangements and this Agreement.

     H.   RULE 144.  The Company covenants that it shall file any reports
required to be filed by it under the Securities Act and the Securities Exchange
Act of 1934 and the rules and regulations thereunder, and it shall take such
further action, that any Affiliated Holder may reasonably request to enable such
Affiliated Holder to sell Shares, from time to time, without registration under
the Securities Act but within the limitation of the exemptions provided by (1)
Rule 144 under the Securities Act, as such Rule may be amended from time to
time, or (2) any similar rule or regulation hereafter adopted by the SEC. Upon
the request of any Affiliated Holder, the Company shall deliver to such
Affiliated Holder a written statement as to whether it has complied with such
requirements.

V.   CLOSING.

     A.   TIME AND LOCATION.  The closing of the transactions contemplated by
this Agreement (the "Closing") shall be subject to the accuracy in all material
respects of the representations and warranties of the parties hereto as though
made on an as of the date of Closing and shall take place contemporaneously with
the closing of the Offerings, at such time and place as the parties hereto may
mutually agree.

     B.   OBLIGATIONS AT THE CLOSING.  Subject to the conditions set forth in
this Agreement, at the Closing:

                                      29 
<PAGE>

          1.   the LLC shall have redeemed NBCC's Redeemable Interest as
contemplated by Section I.A. hereof, and made the distribution contemplated by
Section I.B. hereof;

          2.   the sale of the Valley Common Stock shall be consummated in
accordance with Section I.C. hereof;    

          3.   the sale of CSL assets shall be consummated in accordance with
Section I.D. hereof; 

          4.   the Company shall issue and deliver the shares of Company Common
Stock to the LLC Members and the Merger shall be consummated in accordance with
Section II.A. hereof;

          5.   Valley, CSL, the LLC and the Affiliated Holders shall perform,
satisfy and comply in all material respects all other covenants and conditions
required by this Agreement to be performed, satisfied or complied with on or
before the Effective Date; and

          6.   the Company shall perform, satisfy and comply in all material
respects all other covenants and conditions required by this Agreement to be
performed, satisfied or complied with on or before the Effective Date.

VI.  REMEDIES.

     A.   Each of the parties to this Agreement shall be entitled to enforce its
rights under this Agreement specifically, to recover damages by reason of any
breach of any provision of this Agreement and to exercise all of the rights
existing in its favor.  The parties hereto agree and acknowledge that money
damages may not be an adequate remedy for any such breach or threatened breach
of the provisions of this Agreement and that any party may in its sole
discretion, in addition to any other available remedies, apply to any court of
law or equity of competent jurisdiction for and be entitled to receive or be
entitled to, specific performance and injunctive relief in order to enforce or
prevent any violations of the provisions of this Agreement, without the
necessity of demonstrating that it has been irreparably harmed.  The
representations and warranties in this Agreement shall survive the Closing.

                                      30 
<PAGE>

     B.   In the event a party brings an action under this Agreement, the
prevailing party in such dispute shall be entitled to recover from the losing
party any fees, costs and expenses of enforcing any right of such prevailing
party under or with respect to this Agreement, including, without limitation,
the reasonable fees and expenses of its attorneys and accountants and all fees,
costs and expenses of appeals.

VII. MISCELLANEOUS.

     A.   NOTICES.  All notices and other communications required or permitted
to be given hereunder shall be in writing and shall be deemed to have been duly
given if delivered personally, mailed by certified mail (return receipt
requested) or sent by overnight delivery service, facsimile transmission or
telex to the parties at the following addresses or at such other addresses as
shall be specified by the parties by like notice:

     If to the LLC, Valley, CSL or the Company:

               400 W. Illinois
               Suite 1000
               Midland, Texas 79701
               Attention: Michael J. Grella

     If to Liedtke, Grella or Musselman, to each of such persons at the
following address:

               400 W. Illinois
               Suite 1000
               Midland, Texas 79701
     
     If to NBCC:

               100 N. Tryon Street
               Charlotte, North Carolina 28255
               Attention:  Travis Hain and Robert H. Sheridan, III

Notice so given shall, in the case of notice so given by mail, be deemed to be
given and received on the third calendar day after posting; in the case of
notice so given by overnight delivery services, on the date of actual delivery
and, in the case of notice so given by facsimile transmission, telex or personal
delivery, on the date of actual transmission or, as the case may be, on the day
of personal delivery.

                                      31 
<PAGE>

     B.   TERMINATION OF PRIOR AGREEMENTS.  This Agreement fully replaces and
supersedes all prior agreements relating to the common stock of, or the
membership interest or other interest in, the LLC, CSL, Valley or their
respective predecessors, including, but not limited to, (i) the Regulations of
the LLC dated February 17, 1995; (ii) the Membership Subscription Agreement
dated February 17, 1995 among the LLC, NBCC and each other holder of the within-
mentioned purchase interest; (iii) the Buy-Sell Agreement dated February 17,
1995 (the "LLC Buy-Sell Agreement") by and between the LLC and Liedtke, Grella
and Musselman and their respective spouses, being Marion Liedtke, Katherine
Riggs Grella and Melinda Musselman (collectively, "Spouses"); and (iv) the Buy-
Sell Agreement dated February 17, 1995 by and between Liedtke, Grella and
Musselman and their respective Spouses, CSL Management Corporation, Valley
Gathering Company and 511 TEX L.C. (collectively, the "Prior Agreements").  As a
result of the execution of this Agreement, the parties hereto declare the Prior
Agreements to be of no further force and effect and any notices required
thereunder shall be superseded hereby; provided, however, that if the closing
does not incur on or before October 9, 1996, the Prior Agreements shall be
revived in their entirety.

     C.   SEVERABILITY AND REFORMATION.  The parties hereto intend all of the
provisions of this Agreement to be enforced to the fullest extent permitted by
law.  If, however, any provision of this Agreement is held to be illegal,
invalid or unenforceable under present or future law, then such illegality,
invalidity or unenforceability shall not invalidate the entire Agreement.  Such
provision shall be deemed modified to the extent necessary to render it legal,
valid and enforceable, and if no such modification shall render it legal, valid,
and enforceable, then this Agreement shall be construed and enforced as if such
illegal, invalid, or unenforceable provision were never a part thereof, and the
remaining provisions shall remain in full force and effect and shall not be
affected by the illegal, invalid, or unenforceable provision or by its
severance.

     D.   ENTIRE AGREEMENT; AMENDMENT.  This Agreement, together with the
Exhibits attached hereby and those documents expressly referred to herein,
contains the entire understanding and agreement 

                                      32 
<PAGE>

among the parties to this Agreement, and supersedes any other agreement among 
such parties, whether oral or in writing, with respect to the subject matter 
hereof.  This Agreement may not be altered, amended, rescinded or revoked, 
nor may any of its provisions be waived, except by an instrument in writing 
signed by all of the parties hereto or, in the case of an asserted waiver, by 
the party or parties against whom the waiver is sought to be enforced.

     E.   COUNTERPARTS.  This Agreement may be executed in any number of
counterparts and by different parties hereto in separate counterparts, with the
same effect as if all parties had signed the same document.  All such
counterparts shall be deemed an original, shall be construed together and shall
constitute one and the same instrument.

     F.   SUCCESSORS AND ASSIGNS.  This Agreement is intended to bind and inure
to the benefit of, and be enforceable by and against, each of the parties hereto
and their respective successors and assigns.

     G.   GOVERNING LAW AND VENUE.  ALL QUESTIONS CONCERNING THE CONSTRUCTION,
VALIDITY AND INTERPRETATION OF THIS AGREEMENT WILL BE GOVERNED BY AND CONSTRUED
IN ACCORDANCE WITH THE INTERNAL LAW, AND NOT THE LAW OF CONFLICTS, OF THE STATE
OF TEXAS.  THIS AGREEMENT IS PERFORMABLE IN MIDLAND COUNTY, TEXAS, AND VENUE OF
ANY ACTION RELATED OR PERTAINING TO THIS AGREEMENT SHALL LIKE IN MIDLAND COUNTY,
TEXAS.

     IN WITNESS WHEREOF, the parties hereto have executed this Agreement as of
the day and year first above written, to be effective, however, at the Closing.
                              
                              COSTILLA ENERGY, INC.


                              By:                                             
                                 -------------------------------------------- 
                              Name: Cadell S. Liedtke
                              Title: Chairman of the Board


                              COSTILLA ENERGY, L.L.C.



                                      33 
<PAGE>

                              By:                                             
                                 -------------------------------------------- 
                              Name: Michael J. Grella
                              Title: President




                                                                              
                              ----------------------------------------------- 
                              Cadell S. Liedtke, Individually



                              ----------------------------------------------- 
                              Michael J. Grella, Individually


                                                                              
                              ----------------------------------------------- 
                              Henry G. Musselman, Individually


                              NATIONSBANC CAPITAL CORPORATION


                              By:                                             
                                 -------------------------------------------- 
                              Name: 
                              Title: 


                              CSL MANAGEMENT CORPORATION


                              By:                                             
                                 -------------------------------------------- 
                              Name: 
                              Title: 


                              VALLEY GATHERING COMPANY


                              By:                                             
                                 -------------------------------------------- 
                              Name:
                              Title: 
















                                      34 

<PAGE>

                                                     EXHIBIT 10.6




==================================================================




                 *      *      *      *        *

                     1996 STOCK OPTION PLAN

                               OF


                      COSTILLA ENERGY, INC.
                    (A DELAWARE CORPORATION)

                 *      *      *      *        *



==================================================================



<PAGE>

                        TABLE OF CONTENTS

                        *      *      *        

                     1996 STOCK OPTION PLAN

                               OF

                      COSTILLA ENERGY, INC.


==================================================================

SECTION                      SUBJECT                         PAGE


1.   PURPOSE . . . . . . . . . . . . . . . . . . . . . . . . .  1

2.   CERTAIN DEFINITIONS . . . . . . . . . . . . . . . . . . .  1

3.   INCENTIVE STOCK OPTIONS AND NONSTATUTORY STOCK OPTIONS. .  5

4.   ADMINISTRATION. . . . . . . . . . . . . . . . . . . . . .  6
          4.1  GENERAL . . . . . . . . . . . . . . . . . . . .  6
          4.2  ACTIONS OF BOARD. . . . . . . . . . . . . . . .  7
          4.3  CONDITIONAL GRANTS. . . . . . . . . . . . . . .  7

5.   ELIGIBILITY AND PARTICIPATION . . . . . . . . . . . . . .  7
          5.1  ELIGIBLE EMPLOYEES. . . . . . . . . . . . . . .  7
          5.2  OPTION PRICE. . . . . . . . . . . . . . . . . .  8
          5.3  OPTION AGREEMENT. . . . . . . . . . . . . . . .  8

6.   SHARES OF COMMON STOCK SUBJECT TO THE PLAN. . . . . . . .  8
          6.1  MAXIMUM NUMBER. . . . . . . . . . . . . . . . .  8
          6.2  CAPITAL CHANGES . . . . . . . . . . . . . . . .  9

7.   EXERCISE OF STOCK OPTIONS . . . . . . . . . . . . . . . .  9
          7.1  TIME OF EXERCISE. . . . . . . . . . . . . . . .  9
          7.2  SURRENDER OF SHARES IN PAYMENT OF EXERCISE
                PRICE. . . . . . . . . . . . . . . . . . . . . 10
          7.3  USE OF PROMISSORY NOTE; EXERCISE LOANS. . . . . 10
          7.4  STOCK RESTRICTION AGREEMENT . . . . . . . . . . 11
          7.5  TERMINATION OF EMPLOYMENT BEFORE EXERCISE . . . 11
          7.6  GRANT OF SUPPLEMENTAL BONUSES . . . . . . . . . 12
          7.7  OPTION VESTING UPON CHANGE OF CONTROL OF THE
                COMPANY. . . . . . . . . . . . . . . . . . . . 13

<PAGE>

          7.8  STAND-ALONE, ADDITIONAL, TANDEM, AND
                SUBSTITUTE AWARDS. . . . . . . . . . . . . . . 13

8.   LIMITED RIGHTS. . . . . . . . . . . . . . . . . . . . . . 14
          8.1  GRANT OF LIMITED RIGHTS . . . . . . . . . . . . 14
          8.2  EXERCISE OF LIMITED RIGHTS. . . . . . . . . . . 15
          8.3  FORM OF PAYMENT . . . . . . . . . . . . . . . . 16
          8.4  TERMINATION . . . . . . . . . . . . . . . . . . 16

9.   NO CONTRACT OF EMPLOYMENT . . . . . . . . . . . . . . . . 16

10.  NO RIGHTS AS A STOCKHOLDER. . . . . . . . . . . . . . . . 16

11.  NON-TRANSFERABILITY . . . . . . . . . . . . . . . . . . . 17

12.  COMPLIANCE WITH RULE 16b-3. . . . . . . . . . . . . . . . 17

13.  AMENDMENT . . . . . . . . . . . . . . . . . . . . . . . . 18

14.  REGISTRATION OF OPTIONED SHARES . . . . . . . . . . . . . 18

15.  WITHHOLDING TAXES . . . . . . . . . . . . . . . . . . . . 18

16.  FINANCING ARRANGEMENTS. . . . . . . . . . . . . . . . . . 19

17.  NONEXCLUSIVITY OF THE PLAN. . . . . . . . . . . . . . . . 19

<PAGE>

                     1996 STOCK OPTION PLAN

                               OF

                      COSTILLA ENERGY, INC.

1.   PURPOSE.

     The purpose of this 1996 Stock Option Plan (the "Plan") is to enable 
Costilla Energy, Inc. (the "Company"), and such of its subsidiary 
corporations (as defined in Section 424(f) of the Internal Revenue Code of 
1986 (the "Code")) as the Board of Directors of the Company (the "Board") 
shall from time to time designate ("Participating Subsidiaries"), to attract 
and retain qualified employees, and to provide such persons with additional 
motivation to advance the interests of the Company and its Participating 
Subsidiaries.  The Plan provides for the grant of Stock Options, both 
Incentive Stock Options (under Code Section 422) and nonqualified stock 
options (under Code Section 83), Limited Rights, and Supplemental Bonuses to 
employees of the Company. 

2.   CERTAIN DEFINITIONS.

     2.1  "CHANGE OF CONTROL."  The term "Change of Control" shall mean any 
of the following events:

          (A)  any "Person," as such term is used in Sections 13(d) and 14(d) 
of the Exchange Act (other than the Company, any trustee or other fiduciary 
holding securities under an employee benefit plan of the Company, or any 
company owned, directly or indirectly, by the stockholders of the Company in 
substantially the same proportions as their ownership of stock of the 
Company) becomes the "Beneficial Owner" as defined in Rule 13d-3 under the 
Exchange Act 

                                       1

<PAGE>

after (but not as a direct result of) the completion of the Company's initial 
public offering, directly or indirectly, of 25% or more of the combined 
voting power of the Company's outstanding securities. 

          (B)  individuals who constitute the Board on the effective date of 
the Plan (the "Incumbent Board") cease for any reason to constitute at least 
a majority thereof, provided that any person becoming a director subsequent 
to such effective date whose election, or nomination for election, by the 
Company's stockholders, was approved by a vote of at least a majority of the 
directors comprising the Incumbent Board (either by a specific vote or by 
approval of the proxy statement of the Company in which such person is named 
as a nominee for director, without objection to such nomination) shall be, 
for purposes of this clause (B), considered as though such person were a 
member of the Incumbent Board;

          (C)  the stockholders of the Company shall approve a merger, 
consolidation, recapitalization, or reorganization of the Company, a reverse 
stock split of outstanding voting securities, or consummation of any such 
transaction if stockholder approval is not obtained, other than (1) any such 
transaction which would result in at least 50% of the total voting power 
represented by the voting securities of the surviving entity outstanding 
immediately after such transaction being "Beneficially Owned" (as defined 
above) by 75% or more of the holders of outstanding voting securities of the 
Company immediately prior to the transaction, with the voting power of each 
such continuing holder relative to other such continuing holders not 
substantially altered in the transaction, or (2) a merger or consolidation 
effected to implement a recapitalization of the Company (or similar 
transaction) in which no "Person" (as defined above) acquires more than 25% 
of the combined voting power of the Company's then outstanding securities; or 


                                       2

<PAGE>

          (D)  the stockholders of the Company approve a plan of complete 
liquidation of the Company or an agreement for the sale or disposition by the 
Company of all or substantially all of the Company's assets.

     Notwithstanding anything in the foregoing to the contrary, no Change of 
Control shall be deemed to have occurred with respect to any particular 
Employee by virtue of any transaction which results in such Employee, or a 
group of Persons which includes such Employee, acquiring, directly or 
indirectly, 25% or more of the combined voting power of the Company's 
outstanding securities.

     2.2  "COMMON STOCK."   Common Stock means Common Stock, par value $0.10 
per share, of the Company.

     2.3  "EMPLOYEE."   An Employee is an employee of the Company or any 
Participating Subsidiary.

     2.4  "EXCHANGE ACT."   Exchange Act means the Securities Exchange Act of 
1934, as amended from time to time.

     2.5  "FAIR MARKET VALUE."   The Fair Market Value of a share of Common 
Stock on any date shall be the closing price of the Common Stock as reported 
in the Wall Street Journal for securities listed on The Nasdaq Stock Market's 
National Market (the "Nasdaq National Market"), or other exchange on which 
the Common Stock is traded, for the date in question, or if no closing price 
is available, the closing price on the next preceding date for which a 
closing price was so reported, unless otherwise specified by the Board.  If 
the Common Stock is not listed on The Nasdaq National Market or traded on 
another exchange, the Fair Market Value shall be such amount as determined by 
the Board.


                                       3

<PAGE>

     2.6  "LIMITED RIGHT."   A Limited Right is the right to receive payment, 
in cash, following a Change of Control, of an amount equal to the product 
computed by multiplying (i) the excess of (A) the higher of (x) the Minimum 
Price Per Share, if the Change of Control occurs as a result of a 
Transaction, tender offer or exchange offer, or (y) the highest Fair Market 
Value per share during the period commencing thirty days prior to the Change 
of Control and ending immediately prior to the date the Limited Right is 
exercised, over (B) the option price per share under the Stock Option to 
which such Limited Right relates, by (ii) the number of shares of Common 
Stock as to which such Limited Right is being exercised provided that, in the 
case of any ISO (as defined herein), the amount computed under part (A) of 
the foregoing formula shall be equal to the Fair Market Value of Common Stock 
on the date the Limited Right is, in fact, exercised.  

     2.7  "MINIMUM PRICE PER SHARE."   Minimum Price Per Share means the 
highest gross price (before brokerage commissions and soliciting dealer's 
fees) paid or to be paid for a share of Common Stock (whether by way of 
exchange, conversion, distribution or upon liquidation or otherwise) in any 
Transaction, tender offer or exchange offer occurring prior to the date on 
which such Limited Right is exercised.  If the consideration paid or to be 
paid in any such Transaction, tender offer or exchange offer shall consist, 
in whole or in part, of consideration other than cash, the Board shall take 
such action, as in its judgment it deems appropriate, to establish the cash 
value of such consideration, but such valuation shall not be less than the 
value, if any, attributed to such consideration in writing by any party to 
such Transaction, tender offer or exchange offer other than the Company.  

                                       4

<PAGE>


     2.8  "PARTICIPANT."   A Participant is an Employee to whom a Stock 
Option, Limited Right or Supplemental Bonus is granted.

     2.9  "OPTION PRICE."   The purchase price per share of Common Stock 
subject to a Stock Option is set pursuant to Section 5.2.

     2.10 "STOCK OPTION."   A Stock Option is the right granted under the 
Plan to an Employee to purchase, at such time or times and at such Option 
Price or prices as are determined by the Board, the number of shares of 
Common Stock determined by the Board.

     2.11 "SUPPLEMENTAL BONUS."   A Supplemental Bonus is the right to 
receive payment, in shares of Common Stock, cash or a combination of shares 
of Common Stock and cash, of an amount specified by the Board pursuant to 
Section 7.6.

     2.12 "TRANSACTION."   A Transaction is (A) any consolidation or merger 
of the Company in which the Company is not the surviving corporation other 
than a merger solely to effect a reincorporation or a merger of the Company 
as to which stockholder approval is not required pursuant to Section 251(f) 
or 253 of the Delaware General Corporation Law, or (B) any sale, lease, 
exchange or other transfer (in one transaction or a series of related 
transactions) of 50% or more of the assets or earning power of the Company, 
or (C) the adoption of any plan or proposal for the liquidation or 
dissolution of the Company.

     For purposes of this Plan, the Board may, by resolution, clarify the 
date as of which a Change of Control shall be deemed to have occurred.

3.   INCENTIVE STOCK OPTIONS AND NONSTATUTORY STOCK OPTIONS.

     The Stock Options granted under the Plan may be either:


                                       5

<PAGE>

     (a)  Incentive Stock Options ("ISOs") which are intended to be 
"incentive stock options" as that term is defined in Section 422(b) of the 
Code; or 

     (b)  Nonstatutory Stock Options ("NSOs") which are intended to be 
options that do not qualify as "incentive stock options" under Section 422 of 
the Code.

     The individual Option Agreement(s) (as defined in Section 5.3) shall 
clearly designate whether the Stock Options granted are ISOs or NSOs.  
Subject to other provisions of the Plan, a Participant may receive ISOs or 
NSOs.  Subject to other provisions of the Plan, a Participant may receive 
ISOs and NSOs at the same time, provided that the ISOs and NSOs are clearly 
designated as such.

     Except as otherwise expressly provided herein, all of the provisions and 
requirements of the Plan relating to Stock Options shall apply to both ISOs 
and NSOs.  

4.   ADMINISTRATION.

     4.1  GENERAL.  The Plan shall be administered by the Board. Subject to 
the provisions of the Plan, the Board shall have full authority to administer 
the Plan, including authority to grant awards under the Plan and determine 
the terms thereof, to interpret and construe any provision of the Plan and 
any Stock Option, Limited Right or Supplemental Bonus granted thereunder, to 
adopt such rules and regulations for administering the Plan, including those 
it may deem necessary in order to comply with the requirements of the Code or 
in order that Stock Options that are intended to be ISOs will be classified 
as incentive stock options under the Code, or in order to conform to any 
regulation or to any change in any law or regulation applicable thereto, and 
to make all other decisions and determinations under the Plan.  


                                       6

<PAGE>

     4.2  ACTIONS OF BOARD.  All actions taken and all interpretations and 
determinations made by the Board in good faith (including determinations of 
Fair Market Value) shall be final and binding upon all Participants (their 
heirs, personal representative, administrators and assigns), the Company and 
all other interested persons.  No member of the Board shall be personally 
liable for any action, determination or interpretation made in good faith 
with respect to the Plan, and all members of the Board shall, in addition to 
their rights as directors, be fully protected by the Company with respect to 
any such action, determination or interpretation.

     4.3  CONDITIONAL GRANTS.  All Stock Options, Limited Rights and 
Supplemental Bonuses granted prior to the date the Company's Registration on 
Form S-1 with respect to the Common Stock is declared effective by the 
Securities and Exchange Commission are expressly conditioned upon such 
effectiveness.  If such effectiveness is not obtained within one (1) year of 
the Effective Date, such conditionally granted Stock Options, Limited Rights 
and Supplemental Bonuses shall automatically terminate and be of no effect or 
value.  In addition to any other limitations provided herein, no Stock Option 
or Limited Right may be exercised until such Registration Statement is 
declared effective by the Securities and Exchange Commission.

5.   ELIGIBILITY AND PARTICIPATION.

     5.1  ELIGIBLE EMPLOYEES.  Grants of Stock Options, Limited Rights and 
Supplemental Bonuses may be made to Employees.  Any director of the Company 
or of a Participating Subsidiary who is also an Employee shall also be 
eligible, but directors who are not Employees shall not be eligible, to 
receive Stock Options, Limited Rights or Supplemental Bonuses under the Plan. 
 The Board shall from time to time determine the Employees to whom Stock 
Options shall be granted, whether the option is an ISO, an NSO or combination 
of both, the number of shares 


                                       7

<PAGE>

of Common Stock subject to each Stock Option to be granted to each such 
Employee, the Option Price of such Stock Options and the terms and conditions 
of such Stock Options, including the terms of exercise of the Stock Options, 
subject to the provisions of this Plan.

     5.2  OPTION PRICE.  Except as otherwise provided in Section 7.8, the 
Option Price of any ISO or NSO shall not be less than the Fair Market Value 
of a share of Common Stock on the date on which the Stock Option is granted 
and shall not be less than par value of Common Stock.  If an ISO is granted 
to any Employee who, at the time of the grant, owns stock possessing more 
than 10% of the total combined voting power of all classes of stock of the 
Company or any parent or subsidiary corporation of the Company, the Option 
Price of such ISO shall be at least 110% of the Fair Market Value of the 
Common Stock subject to the ISO on the date such ISO is granted, and such ISO 
shall not be exercisable after five years after the date on which it was 
granted.

     5.3  OPTION AGREEMENT.  Each Stock Option shall be evidenced by a 
written agreement ("Option Agreement") containing such terms and provisions 
of the grant as the Board may determine including without limitation those 
terms set by the Board pursuant to Section 5.1 and 7.1 subject to the 
provisions of this Plan, which may be incorporated into the Option Agreement 
by reference.  

6.   SHARES OF COMMON STOCK SUBJECT TO THE PLAN.

     6.1  MAXIMUM NUMBER.  The maximum aggregate number of shares of Common 
Stock that may be issued under the Plan shall be 850,000 shares, subject to 
adjustment as provided in Section 6.2. Such shares may be authorized and 
unissued shares or may be treasury shares.  The aggregate Fair Market Value 
(determined as of the time an ISO is granted) of the Common Stock as to which 
all ISOs granted to an individual may first become exercisable in a 
particular calendar 


                                       8

<PAGE>

year may not exceed $100,000; provided that to the extent that Stock Options 
intended to be ISOs (together with all incentive stock options granted under 
other Company plans to such individual) become exercisable in a given year in 
excess of $100,000, such portion of the Stock Options shall be deemed to be 
NSOs and shall be exercisable as such.  If any shares of Common Stock subject 
to Stock Options are not purchased or otherwise paid for before such Stock 
Options expire or otherwise terminate, unless such Stock Options are 
surrendered upon exercise of Limited Rights, such shares may again be made 
subject to Stock Options or otherwise issued under the Plan.

     6.2  CAPITAL CHANGES.  In the event any changes are made to the shares 
of Common Stock (whether by reason of merger, consolidation, reorganization, 
recapitalization, stock dividend in excess of one percent (1%) at any single 
time, stock split, combination of shares, exchange of shares, extraordinary 
cash dividend, change in corporate structure or otherwise), the Board shall, 
in order to prevent dilution or enlargement of Participant's rights, make 
appropriate adjustments in: (i) the number and kind of shares theretofore 
made subject to Stock Options, and in the Option Price of said shares, and 
(ii) the aggregate number and kind of shares which may be issued under the 
Plan.  If any of the foregoing adjustments shall result in a fractional 
share, the fraction shall be disregarded, and the Company shall have no 
obligation to make any cash or other payment with respect to such a 
fractional share.

7.   EXERCISE OF STOCK OPTIONS.

     7.1  TIME OF EXERCISE.  Subject to the provisions of the Plan, including 
without limitation Section 7.7, the Board, in its discretion, shall determine 
the time when a Stock Option, or a portion of a Stock Option, shall become 
exercisable, and the time when a Stock Option, or a portion of a Stock 
Option, shall expire.  Such time or times shall be set forth in the Option 


                                       9

<PAGE>


Agreement evidencing such Stock Option.  An ISO shall expire, to the extent 
not exercised, no later than the tenth anniversary date of the date on which 
it was granted, and an NSO shall expire, to the extent not exercised, no 
later than 10 years and one day after the date on which it was granted.  The 
Board may accelerate the vesting of any Participant's Stock Option by giving 
written notice to the Participant.  Unless otherwise determined by the 
Committee, the acceleration of the exercise period of a Stock Option shall 
not affect the expiration date of that Stock Option.

     7.2  SURRENDER OF SHARES IN PAYMENT OF EXERCISE PRICE.  The Board, in 
its sole discretion, may permit a Participant to surrender to the Company 
shares of Common Stock as part or full payment for the exercise of a Stock 
Option.  Such surrendered shares shall be valued at their Fair Market Value 
on the date of exercise.  Unless otherwise determined by the Board, any such 
shares surrendered by the Participant shall have been held by him for at 
least six months prior to surrender. 

     7.3  USE OF PROMISSORY NOTE; EXERCISE LOANS.  The Board may, in its sole 
discretion, impose terms and conditions, including conditions relating to the 
manner and timing of payments of the Option Price, on the exercise of Stock 
Options.  Such terms and conditions may include, but are not limited to, 
permitting a Participant to deliver to the Company his promissory note as 
payment for the exercise of a Stock Option; provided that, with respect to 
any promissory note given as payment or partial payment for the exercise of 
an ISO, all terms of such note, including collateral securing the same, shall 
be determined at the time the Stock Option is granted and set forth in the 
Option Agreement.  The Board, in its sole discretion, may authorize the 
Company to make a loan to a Participant in connection with the exercise of 
Stock Options, or 


                                       10

<PAGE>

authorize the Company to make a loan to a Participant in connection with the 
exercise of Stock Options, or authorize the Company to arrange or guaranty 
loans to a Participant by a third party, including in connection with 
broker-assisted cashless exercises.  The foregoing notwithstanding, a 
Participant shall pay at least the par value of the Common Stock to be 
acquired upon exercise of a Stock Option in the form of lawful consideration 
under the Delaware General Corporation Law prior to issuance of such shares.  

     7.4  STOCK RESTRICTION AGREEMENT.  The Board may provide that shares of 
Common Stock issuable upon the exercise of a Stock Option shall, under 
certain conditions, be subject to restrictions whereby the Company has a 
right of first refusal with respect to such shares or a right or obligation 
to repurchase all or a portion of such shares, which restrictions may survive 
a Participant's term of employment with the Company. The acceleration of time 
or times at which the Stock Option becomes exercisable may be conditioned 
upon the Participant's agreement to such restrictions.

     7.5  TERMINATION OF EMPLOYMENT BEFORE EXERCISE.  If a Participant's 
employment with the Company or a Participating Subsidiary shall terminate for 
any reason other than the Participant's disability, any ISO then held by the 
Participant, to the extent then exercisable under the applicable Option 
Agreement(s), shall remain exercisable after the termination of his 
employment for a period of three months from date of termination.  If the 
Participant's employment is terminated because the Participant is disabled 
within the meaning of Section 22(e)(3) of the Code, any ISO then held by the 
Participant, to the extent then exercisable under the applicable Option 
Agreement(s), shall remain exercisable after the termination of his 
employment for a period of one year (but in no event beyond ten years from 
the date of grant of the ISO) by the Participant or his legal representative. 
 If the Stock Option is not exercised during 


                                       11

<PAGE>

the applicable period, it shall be deemed to have been forfeited and of no 
further force or effect.  The period and extent to which an NSO may be 
exercised following termination of employment shall be determined by the 
Board and set forth in the Option Agreement.  Notwithstanding the foregoing, 
a Stock Option, whether an ISO or NSO, held by a Participant at the 
Participant's death shall be exercisable by the Participant's personal 
representative, estate or heirs until the later of (i) the expiration of the 
Stock Option or (ii) one year after death.

     7.6  GRANT OF SUPPLEMENTAL BONUSES.  The Board, either at the time of 
grant or at any time prior to exercise of any NSO or Limited Right, may 
provide for a Supplemental Bonus from the Company or Participating Subsidiary 
in connection with a specified number of shares of Common Stock then 
purchasable, or which may become purchasable, under an NSO, or a specified 
number of Limited Rights which may be or become exercisable.  A Supplemental 
Bonus shall be automatically payable upon the exercise of the NSO or Limited 
Right with regard to which such the Supplemental Bonus was granted.  A 
Supplemental Bonus shall not exceed the amount necessary to reimburse the 
Participant for the income tax liability incurred by him upon the exercise of 
the NSO or upon the exercise of such Limited Right, calculated using the 
maximum combined federal and applicable state income tax rates then in effect 
and taking into account the tax liability incurred by him upon the exercise 
of the NSO or upon the exercise of such Limited Right, calculated using the 
maximum combined federal and applicable state income tax rates than in effect 
and taking into account the tax liability arising from the Participant's 
receipt of the Supplemental Bonus, all as determined by the Committee.  The 
Committee may, in its discretion, elect to pay any part or all of the 
Supplemental Bonus in:  (i) cash; (ii) shares of Common Stock; or (iii) any 
combination of cash and shares of Common Stock; provided that 


                                       12

<PAGE>

bonuses payable in respect of Limited Rights shall be payable only in cash.  
The Board's determination to grant a Supplemental Bonus shall be made by 
giving written notice to the Participant not later than 90 days after the 
related exercise, which notice shall specify the portion which the Board 
elects to pay in cash, shares of Common Stock or a combination thereof.  In 
the event any portion is to be paid in shares of Common Stock, the number of 
shares to be delivered shall be determined by dividing the amount which the 
Board elects to pay in shares of Common Stock by the Fair Market Value of one 
share of Common Stock on the date of exercise.  Any fractional shares 
resulting from any such calculation shall be disregarded.  Said shares, 
together with any cash payable to the Participant, shall be delivered within 
said 90-day period.  

     7.7  OPTION VESTING UPON CHANGE OF CONTROL OF THE COMPANY. In the event 
of a Change of Control of the Company the vesting of Stock Options granted 
pursuant to the Plan shall automatically be accelerated, so that all Stock 
Options outstanding at the time of such Change of Control will be exercisable 
immediately except as otherwise provided in Section 2.1.

     7.8  STAND-ALONE, ADDITIONAL, TANDEM, AND SUBSTITUTE AWARDS. Awards 
granted under the Plan may, in the discretion of the Board, be granted either 
alone or in addition to, in tandem with, or in substitution for, any other 
award granted under the Plan or any other plan of the Company or any 
Participating Subsidiary or any other right of a Participant to receive 
payment from the Company or any Participating Subsidiary.  If an award is 
granted in substitution for another such award, the Board shall require the 
surrender of such other award in consideration for the grant of the new 
award.  Awards granted in addition to or in tandem with other awards may be 
granted either as of the same time as or a different time from the grant of 
such other awards.  The per share Option Price of any Stock Option:


                                       13


<PAGE>
          (A)  Granted in substitution for an outstanding
     award shall be not less than the lesser of the Fair
     Market Value of a share of Common Stock from the date
     such substitute award is granted or such Fair Market
     Value at that date reduced to reflect the fair market
     value (as determined by the Board) at that date of the
     award required to be surrendered by the Participant as
     a condition to receipt of the substitute award; or 
          (B)  Retroactively granted in tandem with an
     outstanding award shall be not less than the lesser of
     the Fair Market Value of a share of Common Stock at the
     date of grant of the later award or at the date of
     grant of the earlier award.

Except for the Option Price required to be paid upon the exercise of Stock 
Options and except as provided in this Section 7.8, only services may be 
required as consideration for the grant of any award under the Plan.

8.   LIMITED RIGHTS.

     8.1  GRANT OF LIMITED RIGHTS.  The Board may in its discretion grant 
Limited Rights to a Participant concurrently with the grant of each ISO or at 
any time with respect to any NSO.  Such Limited Rights shall be exercisable 
with respect to the number of shares of Common Stock which are, or may 
become, purchasable under any such Stock Option.  The Board may, in its 
discretion, specify the terms and conditions of such rights, including 
without limitation the date or dates upon which such rights shall expire and 
become void and unexercisable, except that Limited Rights granted with 
respect to an ISO shall only be exercisable, and shall expire, at the time or 
times the ISO is exercisable and expires, respectively.  Each Participant to 
whom Limited Rights are granted shall be given written notice advising him of 
the grant of such rights and

                                     14
<PAGE>

specifying the terms and conditions of the rights, which shall be subject to 
all the provisions of this Plan.

     8.2  EXERCISE OF LIMITED RIGHTS.  Subject to the limitations set forth 
in Section 8.1, a Limited Right may be exercisable only during the period 
beginning on the first day following the occurrence of a Change of Control 
and ending on the sixtieth day following such date.  Upon the occurrence of a 
tender or exchange offer constituting a Change of Control, a Limited Right 
may be exercised in such manner regardless of whether the Board supports or 
opposes such tender or exchange offer.  A Participant shall exercise his 
Limited Rights by delivering a written notice to the Board specifying the 
number of shares with respect to which he exercises Limited Rights and 
agreeing to surrender the right to purchase an equivalent number of shares of 
Common Stock subject to his Stock Option.  If a Participant exercises Limited 
Rights, payment of his Limited Rights shall be made in accordance with 
Section 8.3 on or before the thirtieth day after the date of exercise of the 
Limited Rights.  A Limited Right shall remain exercisable during the exercise 
periods specified in accordance with Section 8.1 and this Section in the 
event of a termination of employment of the Participant holding the Limited 
Right after a Change of Control; provided, however, that the Limited Right 
shall expire upon the expiration of the exercise period of the Stock Option 
to which it relates.  Notwithstanding the above, upon a termination of the 
employment of the holder of the Limited Right before the occurrence of any 
Change of Control, the Limited Right shall expire immediately upon such 
termination.

     8.3  FORM OF PAYMENT.  If a Participant elects to exercise 
Limited Rights as provided in Section 8.2, the Company shall pay to the 
Participant in cash the amount set forth in Section 2.7 hereof, calculated 
with respect to the shares as to which the Participant has exercised Limited

                                     15
<PAGE>

Rights, within thirty days after the date of exercise of the Limited Rights.  
If such amount is not paid in full within the prescribed period, the Company 
shall be liable to such Participant for the costs of collection of such 
amount, including attorney's fees.

     8.4  TERMINATION.  When a Limited Right is exercised, the Stock Option 
to which it relates, if any, shall cease to be exercisable to the extent of 
the number of shares of Common Stock with respect to which such Limited Right 
was exercised.  Upon the exercise or termination of a Stock Option, any 
Limited Right granted with respect thereto shall terminate to the extent of 
the number of shares as to which such Stock Option was exercised or 
terminated. 

     9.   NO CONTRACT OF EMPLOYMENT.  
          Nothing in this Plan shall confer upon the Participant the right to 
continue in the employ of the Company, or any Participating Subsidiary, nor 
shall it interfere in any way with the right of the Company, or any such 
Participating Subsidiary, to discharge the Participant at any time for any 
reason whatsoever, with or without cause.  Nothing in this Article 9 shall 
affect any rights or obligations of the Company or any Participant under any 
written contract of employment.

                                     16

<PAGE>

     10.  NO RIGHTS AS A STOCKHOLDER. 
          A Participant shall have no rights as a stockholder with respect to 
any shares of Common Stock subject to a Stock Option, until such Stock Option 
is exercised and certificates representing the shares are issued.  Except as 
provided in Section 6.2, no adjustment shall be made in the number of shares 
of Common Stock issued to a Participant, or in any other rights of the 
Participant upon exercise of a Stock Option by reason of any dividend, 
distribution or other right granted to stockholders for which the record date 
is prior to the date of issuance of shares upon exercise of the Participant's 
Stock Option.

    11.  NON-TRANSFERABILITY. 
         No Stock Option, Limited Right or Supplemental Bonus granted under 
this Plan, nor any other rights acquired by a Participant under this Plan, 
shall be assignable or transferable by a Participant, other than by will or 
the laws of descent and distribution, or pursuant to a qualified domestic 
relations order as defined under Section 1041 of the Code or Title I of the 
Employee Retirement Income Security Act of 1974, and any ISO shall be 
exercisable, during the Participant's lifetime, only by him.  In the event of 
a Participant's death, the Stock Option or any Limited Right or Supplemental 
Bonus may be exercised by the personal representative of the Participant's 
estate or, if no personal representative has been appointed, by the successor 
or successors in interest determined under the Participant's will or under 
the applicable laws of descent and distribution. 

     12. COMPLIANCE WITH RULE 16b-3.  
         It is the intent of the Company that the Plan comply in all respects 
with Rule 16b-3 under the Exchange Acct in connection with any award granted 
to a person who is subject to Section 16

                                     17

<PAGE>

of the Exchange Act.  Accordingly, if any provision of the Plan or any 
agreement hereunder does not comply with the requirements of Rule 16b-3 as 
then applicable to any such person, such provision shall be construed or 
deemed amended to the extent necessary to conform to such requirements with 
respect to such person. 

     13.  AMENDMENT.
          The Company by action of the Board may amend, modify or terminate 
this Plan at any time or may amend, modify or terminate any outstanding 
Option Agreement, except that any such amendment, modification or termination 
of the Plan shall be subject to the approval of the Company's stockholders 
within one year after such Board action if such stockholder approval is 
required by any federal or state law or regulation or the rules of any stock 
exchange or automated quotation system on which the Common Stock may be 
listed or quoted, or if the Board in its discretion determines that obtaining 
such stockholder approval is for any reason advisable.  Moreover, no action 
may be taken by the Company without the consent of the affected Participant 
which will materially impair the rights of such Participant under any award 
then outstanding or which will prevent an ISO from continuing to qualify 
under Section 422 of the Code.

    14.  REGISTRATION OF OPTIONED SHARES.  
         No Stock Option shall be exercisable unless the Company's sale of 
such optioned shares is pursuant to an applicable effective registration 
statement under the Securities Act of 1933, as amended, or unless, in the 
opinion of counsel to the Company, the Company's sale of such

                                     18

<PAGE>

optioned shares would be exempt from the registration requirements of the 
Securities Act of 1933, as amended, and unless, in the opinion of such 
counsel, such sale would be exempt from the registration or qualification 
requirements of applicable state securities laws.

    15.  WITHHOLDING TAXES.
         The Company or a Participating Subsidiary may take such steps as the 
Board may deem necessary or appropriate for the withholding of any taxes 
which the Company or the Participating Subsidiary is required by any law or 
regulation or any governmental authority, whether federal, state or local, 
domestic or foreign, to withhold in connection with any Stock Option, Limited 
Right or Supplemental Bonus, and to take such other action as the Board may 
deem necessary or advisable to enable the Company and Participants to satisfy 
obligations for the payment of tax liabilities in excess of such withholding 
obligations relating to any such award.  This authority shall include 
authority to withhold or receive shares or other property and to make cash 
payments in respect thereof in satisfaction of Participant's tax obligations. 

     16.  FINANCING ARRANGEMENTS.
         The Board, in  its discretion, may enter into arrangements with one 
or more banks, brokers or other financial institutions to facilitate the 
exercise, and the disposition of shares acquired upon exercise, of Stock 
Options or Supplemental Bonuses, including, without limitation, arrangements 
for the simultaneous exercise of Stock Options (including a related 
Supplemental Bonus), and sale of the shares acquired upon such exercise.

    17.  NONEXCLUSIVITY OF THE PLAN.
         Neither the adoption of the Plan by the Board nor the submission of 
the Plan to stockholders of the Company for approval shall be construed as 
creating any limitations on the

                                     19

<PAGE>

power or authority of the Board to adopt such other or additional incentive 
or other compensation arrangements or whatever nature as the Board may deem 
necessary or desirable or preclude or limit the continuation of any other 
plan, practice or arrangement for payment of compensation or fringe benefits 
to employees generally, or to any class or group of employees, which the 
Company or any subsidiary now has lawfully put into effect, including, 
without limitation, any retirement, pension, savings and stock purchase plan, 
insurance, death and disability benefits and executive short-term incentive 
plans.

    18.  EFFECTIVE DATE.
         This Plan shall become effective on September 1, 1996 (the "Effective
Date"), subject to the Company's Registration Statement on Form S-1 with respect
to the Common Stock, file number 333-08913, being declared effective by the 
Securities and Exchange Commission.  If no such effectiveness is obtained on or 
before one (1) year of the Effective Date, the Plan shall terminate, and all 
Stock Options, Limited Rights and Supplemental Bonuses conditionally granted 
hereunder shall be null and void and of no force or effect.  No ISO shall be 
granted subsequent to ten years after the Effective Date.  Unless earlier 
terminated by the Board, the Plan shall terminate when no shares of Common Stock
remain reserved and available for issuance and the Company has no further 
obligation with respect to any award granted under the Plan.

      The foregoing 1996 Stock Option Plan of Costilla Energy, Inc. was 
adopted and approved by the Board of Directors and stockholders of the 
Company on the 26th day of August, 1996.


                                     20

<PAGE>


                                   COSTILLA ENERGY, INC.

                                   By: 
                                      -----------------------------------------
                                         Michael J. Grella
                                         President and Chief Operating Officer

                                     21


<PAGE>

                                                        EXHIBIT 10.7














                                                                  
=============================================================================

                           *     *     *     *     *

                      OUTSIDE DIRECTORS STOCK OPTION PLAN

                                      OF

                             COSTILLA ENERGY, INC.
                           (A DELAWARE CORPORATION)

                           *     *     *     *     *

                                                   
=============================================================================
<PAGE>

                               TABLE OF CONTENTS

                                 *     *     *

                      OUTSIDE DIRECTORS STOCK OPTION PLAN

                                      OF

                             COSTILLA ENERGY, INC.

                                                                  
==============================================================================

      1.    PURPOSE OF PLAN. . . . . . . . . . . . . . . . . . . . . . . .   1

      2.    STOCK SUBJECT TO THE PLAN. . . . . . . . . . . . . . . . . . .   1

      3.    PERSONS ELIGIBLE UNDER THE PLAN. . . . . . . . . . . . . . . .   2

      4.    ADMINISTRATION OF THE PLAN . . . . . . . . . . . . . . . . . .   2
            (a)   GENERAL. . . . . . . . . . . . . . . . . . . . . . . . .   2
            (b)   GRANT OF OPTIONS . . . . . . . . . . . . . . . . . . . .   2
            (c)   CONDITIONAL GRANTS . . . . . . . . . . . . . . . . . . .   3
            (d)   CHANGES IN LAW APPLICABLE. . . . . . . . . . . . . . . .   3

      5.    TERMS AND CONDITIONS OF OPTIONS. . . . . . . . . . . . . . . .   3
            (a)   NUMBER OF SHARES . . . . . . . . . . . . . . . . . . . .   3
            (b)   EXERCISE PRICE . . . . . . . . . . . . . . . . . . . . .   4
            (c)   VESTING. . . . . . . . . . . . . . . . . . . . . . . . .   4
            (d)   OPTION PERIOD. . . . . . . . . . . . . . . . . . . . . .   4
                  (1)   GENERAL. . . . . . . . . . . . . . . . . . . . . .   4
                  (2)   TERMINATION OF STATUS AS OUTSIDE DIRECTOR. . . . .   4
                  (3)   DEATH. . . . . . . . . . . . . . . . . . . . . . .   4
            (e)   EXERCISE OF OPTIONS. . . . . . . . . . . . . . . . . . .   5
            (f)   NON-TRANSFERABILITY OF OPTIONS . . . . . . . . . . . . .   5
            (g)   COMPLIANCE WITH SECURITIES LAWS. . . . . . . . . . . . .   5

      6.    MEDIUM AND TIME OF PAYMENT . . . . . . . . . . . . . . . . . .   6

      7.    RIGHTS AS A STOCKHOLDER. . . . . . . . . . . . . . . . . . . .   7

      8.    ADJUSTMENTS ON CHANGES IN CAPITALIZATION OR
              REORGANIZATION . . . . . . . . . . . . . . . . . . . . . . .   7
            (a)   CHANGES IN CAPITALIZATION. . . . . . . . . . . . . . . .   7
            (b)   REORGANIZATION . . . . . . . . . . . . . . . . . . . . .   8
            (c)   FRACTIONAL SHARES. . . . . . . . . . . . . . . . . . . .   8
            (d)   CHANGE IN PAR VALUE. . . . . . . . . . . . . . . . . . .   8

<PAGE>

            (e)   NOTICE OF ADJUSTMENTS. . . . . . . . . . . . . . . . . .   9
            (f)   NON-ADJUSTABLE EVENTS. . . . . . . . . . . . . . . . . .   9
            (g)   RIGHT OF COMPANY TO MAKE ADJUSTMENTS . . . . . . . . . .   9

      9.    TIME OF GRANTING OPTIONS AND OPTION AGREEMENT. . . . . . . . .   9

      10.   NO OBLIGATION TO EXERCISE OPTION . . . . . . . . . . . . . . .  10

      11.   EFFECTIVE DATE OF THE PLAN . . . . . . . . . . . . . . . . . .  10

      12.   TERMINATION OF THE PLAN. . . . . . . . . . . . . . . . . . . .  10

      13.   MODIFICATION, EXTENSION, AND RENEWAL OF OPTIONS. . . . . . . .  10

      14.   AMENDMENT OF THE PLAN. . . . . . . . . . . . . . . . . . . . .  11
 
                                        ii
<PAGE>

                      OUTSIDE DIRECTORS STOCK OPTION PLAN

                                      OF

                             COSTILLA ENERGY, INC.


      1.    PURPOSE OF PLAN.  This Outside Directors Stock Option Plan (the 
"Plan") is intended to encourage ownership of the common stock of COSTILLA 
ENERGY, INC. (the "Company") by Outside Directors (as hereinafter defined) of 
the Company in order to provide additional incentive for such persons to 
promote the success of the business of the Company and to encourage each of 
them to become and remain an Outside Director of the Company by providing 
such persons an opportunity to benefit from any appreciation of the common 
stock of the Company through the issuance of stock options to such persons in 
accordance with the terms of the Plan.  It is further intended that options 
granted pursuant to this Plan (the "Options") shall constitute non-qualified 
stock options within the meaning of the Internal Revenue Code of 1986 (the 
"Code").  

      2.    STOCK SUBJECT TO THE PLAN.  Subject to adjustment as provided in 
Section 8 hereof, an aggregate of 50,000 shares of the common stock, $.10 par 
value, of the Company (the "Common Stock"), will be reserved and authorized 
for issuance upon the exercise of Options, which shares in whole or in part 
shall be authorized, but unissued, shares of the Common Stock or issued 
shares of Common Stock which are reacquired by the Company as determined from 
time to time by the Board of Directors.  The number of shares of Common Stock 
available at any time for the granting of Options under the Plan shall be 
equal to the total number of reserved shares of Common Stock less the number 
of shares of Common Stock

<PAGE>

underlying outstanding Options or which have been issued upon exercise of 
Options.  If an Option ceases to be exercisable in whole or in part, the 
shares represented by such Option shall continue to be available under the 
Plan for purposes of granting Options with respect thereto.

            The Company will not be required upon the exercise of any Option 
to issue or deliver any shares of stock prior to the completion of such 
registration or other qualification of such shares under any State or Federal 
law, rule or regulation as the Company shall determine to be necessary or 
desirable.

      3.    PERSONS ELIGIBLE UNDER THE PLAN.  Only those persons qualifying 
as Outside Directors, as defined herein, are eligible to participate in the 
Plan and receive Options hereunder.  As used herein, the term "Outside 
Directors" means only those directors of the Company who are not executive 
officers or regular salaried employees of the Company as of the date an 
Option is granted.

      4.    ADMINISTRATION OF THE PLAN.

            (a)  GENERAL.  The grant of options under the Plan shall be 
non-discretionary and based solely upon whether a person is eligible as an 
Outside Director.  The ministerial tasks associated with the Plan, including 
without limitation completing option grant documents, determining the 
exercise prices from objective sources and issuing shares of Common Stock 
upon exercise of an Option, shall be performed by the officers of the 
Company.  Such officers shall have no discretion in performing such tasks, 
and must do so in compliance with the terms of the Plan and applicable law.

            (b)  GRANT OF OPTIONS.  Each person who qualifies as an Outside 
Director shall receive, each year such person so qualifies, an Option for 
1,000 shares of Common Stock.  Such an Option shall be granted

OUTSIDE DIRECTORS STOCK OPTION PLAN - Page 2
<PAGE>

an Option shall be granted annually to each Outside Director on the day 
immediately following the date such Outside Director is elected by the 
stockholders of the Company beginning in 1997 and continuing for ten (10) 
years thereafter; provided, that if no election of directors occurs within a 
thirteen (13) month period after the last such election, such an Option shall 
be granted to each Outside Director on the last day of that thirteen (13) 
month period.  

            (c)  CONDITIONAL GRANTS.  All Options granted prior to the date 
the Company's Registration Statement on Form S-1 with respect to the Common 
Stock, file number 333-08913 is declared effective by the Securities and 
Exchange Commission (the "Commission") are expressly conditioned upon such 
effectiveness. If such effectiveness is not obtained within one (1) year from 
the Effective Date, such conditionally granted Options shall automatically 
terminate and be of no effect or value.  In addition to any other limitations 
provided herein, no Option may be exercised until such Registration Statement 
is declared effective by the Commission.

            (d)  CHANGES IN LAW APPLICABLE.  If the laws relating to 
non-qualified stock options are changed, altered or amended during the term 
of the Plan, the Board of Directors shall have full authority and power to 
alter or amend the Plan to conform to such changes in the law without the 
necessity of obtaining stockholder approval, unless such changes require such 
approval.

      5.    TERMS AND CONDITIONS OF OPTIONS.  All Options granted pursuant to 
this Plan must be granted within ten (10) years from the Effective Date.

            (a)  NUMBER OF SHARES.  Each Option shall represent 1,000 shares 
of Common Stock.

OUTSIDE DIRECTORS STOCK OPTION PLAN - Page 3
<PAGE>

            (b)  EXERCISE PRICE.  The purchase price for each share of Common 
Stock purchased upon exercise of an Option shall be equal to the fair market 
value of a share of Common Stock at the time the Option is granted.  The 
"fair market value" per share of Common Stock shall be equal to the closing 
price of the Common Stock as reported on The Nasdaq Stock Market's National 
Market (the "Nasdaq National Market") or other stock exchange on the day the 
Option is granted, so long as the Common Stock is quoted thereon.  If no sale 
is reported on the day the Option is granted, the "fair market value" shall 
be equal to the closing price reported on the next preceding day on which a 
sale of Common Stock is reported. If the Common Stock is not listed on the 
Nasdaq National Market or another stock exchange, the exercise price shall be 
set by the Board of Directors.

            (c)  VESTING.  Each Option shall be fully vested and exercisable 
on the date such Option is granted, subject to the limitations provided in 
Section 4(c) hereof.

            (d)  OPTION PERIOD.

                 (1)   GENERAL.  Each Option shall state the date
      upon which it is granted.  Each Option shall be exercisable
      for a period of ten (10) years from the date of grant.

                 (2)   TERMINATION OF STATUS AS OUTSIDE DIRECTOR. 
      In the event an optionee's status as an Outside Director is
      terminated for any reason other than the death of such
      optionee prior to the full exercise of an Option, such
      optionee may exercise the Option at any time within six (6)
      months after such termination to the extent the optionee
      was entitled to exercise such option on the date of such
      termination; provided, however, that the Option may not be
      exercised after the expiration of the term of the Option.

                 (3)   DEATH.  If an optionee dies while an Outside
      Director of the Company or during the exercise period
      following termination as provided in Section 5(d)(2) above
      and held unexercised Options granted pursuant to the Plan
      at the time of death, such Options may be exercised in whole or 
      in part at any time within one (1) year 

OUTSIDE DIRECTORS STOCK OPTION PLAN - Page 4
<PAGE>

      after the optionee's death by the executors or administrators 
      of the optionee's estate or by any person or persons who acquire
      the Options directly from the optionee by bequest or inheritance;
      provided, however, that no Option shall be exercisable after the 
      expiration of the term of the Option.

            (e)  EXERCISE OF OPTIONS.  To the extent that a holder of an 
Option has a current right to exercise the Option, said Option may be 
exercised from time to time by written notice to the attention of the 
Secretary of the Company at its principal place of business.  Such notice 
shall state the election to exercise the Option and the number of shares in 
respect of which it is being exercised, and shall be signed and dated by the 
person or persons so exercising the Option.  Such notice shall be accompanied 
by payment of the full purchase price of such shares, as provided in Section 
6 hereof.  The Company will deliver a certificate or certificates 
representing such shares as soon as practicable after such notice and payment 
are received.  The certificate or certificates for the shares as to which the 
Option is exercised will be registered on the books of the Company in the 
name of the person or persons exercising the Option.

            (f)  NON-TRANSFERABILITY OF OPTIONS.  An Option granted pursuant 
to the Plan is exercisable only by the optionee during his or her lifetime 
and is not assignable or transferable by him or her other than by will or the 
laws of descent and distribution.

            (g)  COMPLIANCE WITH SECURITIES LAWS.  At the time of exercise of 
any Option, the Company may require the optionee to execute any documents or 
take any action which may be necessary to comply with the Securities Act of 
1933, as amended, or the Securities Exchange Act of 1934, as amended, and the 
rules and regulations promulgated thereunder, or any other applicable federal 
or state laws regulating the sale and issuance of securities; and the Company 
may, if it deems necessary, include provisions in the  option agreements 
authorized under the 

OUTSIDE DIRECTORS STOCK OPTION PLAN - Page 5
<PAGE>

Plan to assure such compliance.  The Company may, from time to time, change 
its requirements with respect to enforcing compliance with federal and state 
securities laws, including without limitation the request for and enforcement 
of agreements of investment intent, such requirements to be determined by the 
Company in its judgment as necessary to assure compliance with such laws.


      6.    MEDIUM AND TIME OF PAYMENT.  The purchase price of the shares of 
the Common Stock purchased upon the exercise of an Option shall be paid in 
full at the time of exercise and shall be payable in cash in United States 
dollars (including cashier's or certified check, bank draft or money order); 
provided, however, that in lieu of such cash the person exercising the Option 
may pay the exercise price in whole or in part by delivering to the Company 
shares of the Common Stock having a fair market value on the date of exercise 
of the stock option (determined by the closing price of the Common Stock on 
the Nasdaq National Market on that day, or if no price is reported on that 
day, on the next preceding day on which a closing price is reported) equal to 
the purchase price for the shares being purchased; except that (i) any 
portion of the purchase price representing a fraction of a share shall in any 
event be paid in cash and (ii) no shares of the Common Stock which have been 
held for less than six months may be delivered in payment of the purchase 
price of a stock option.  Delivery of shares may be accomplished through the 
effective transfer to the Company of shares of Common Stock held by a broker 
or other agent.  The Company will also cooperate with any person exercising 
an Option who participates in a cashless exercise program of a broker or 
other agent under which all or part of the shares received upon exercise of 
the Option are sold through the broker or other agent or under which the 
broker or other agent makes a loan to such person.  Notwithstanding the 
foregoing, the exercise of the Option shall not be deemed to occur and no 

OUTSIDE DIRECTORS STOCK OPTION PLAN - Page 6
<PAGE>

shares of Common Stock will be issued by the Company upon exercise of the 
Option until the Company has received payment of the purchase price in full.  
The date of exercise of an Option shall be the date of full payment of the 
purchase price.  Payment of the purchase price with shares of Common Stock 
will not increase the number of shares of Common Stock that may be issued 
under the Plan as provided in Section 2.  

      7.    RIGHTS AS A STOCKHOLDER.  The holder of an Option shall have no 
rights as a stockholder of the Company with respect to the shares covered by 
his or her Option until the due exercise of the Option and the date of 
issuance of one or more stock certificates to him or her for such shares.  No 
adjustment shall be made for dividends (ordinary or extraordinary, whether in 
cash, securities or other property) or distributions or other rights for 
which the record date is prior to the date such stock certificate(s) are 
issued and delivered, except as provided in Section 8 hereof.  

      8.    ADJUSTMENTS ON CHANGES IN CAPITALIZATION OR REORGANIZATION.

            (a)  CHANGES IN CAPITALIZATION.  Subject to any required action 
by the stockholders of the Company, the number of shares of Common Stock 
covered by the Plan as provided in Section 2 hereof, the number of shares of 
Common Stock covered by each outstanding Option, and the exercise price per 
share specified in each such Option, shall be proportionately adjusted for 
any increase or decrease in the number of issued shares of Common Stock of 
the Company after the date the Option is granted resulting from a subdivision 
or consolidation of shares, or the payment of a stock dividend (but only on 
the Common Stock), stock split, or any other increase or decrease in the 
number of such shares effected without receipt of consideration by the 
Company, so that upon exercise of the Option, the optionee shall receive the 
same proportionate number of shares he or she would have received had he or 
she 

OUTSIDE DIRECTORS STOCK OPTION PLAN - Page 7
<PAGE>

been the holder of all shares subject to his or her outstanding Options 
immediately before the effective date of such change in the number of issued 
shares of the Common Stock of the Company.

            (b)  REORGANIZATION.  Subject to any required action by the 
stockholders of the Company, if the outstanding shares of the Common Stock 
shall be changed into or exchangeable for a different number or kind of 
shares of stock or other securities of the Company or another entity, whether 
through reorganization, reclassification, recapitalization, stock split-up, 
combination of shares, merger or consolidation, then there shall be 
substituted for each share of the Common Stock set forth in Section 2, for 
each share of the Common Stock subject to any then outstanding Option and for 
each share of the Common Stock which may be issued under the Plan but which 
is not then subject to any outstanding Option, the number and kind of shares 
of stock or other securities into which each outstanding share of the Common 
Stock shall be so changed or for which each such share shall be exchangeable.

            (c)  FRACTIONAL SHARES.  No adjustment or substitution provided 
for in this Section 8 shall require the Company to issue or sell a fraction 
of a share or other security.  Accordingly, all fractional shares or other 
securities which result from any such adjustment or substitution shall be 
eliminated and not carried forward to any subsequent adjustment or 
substitution.

            (d)  CHANGE IN PAR VALUE.  In the event of a change in the Common 
Stock of the Company as presently constituted, which change is limited to a 
change of all of its authorized shares with par value into the same number of 
shares with a different par value or without par value, the shares resulting 
from any such change shall be deemed to be the Common Stock within the 
meaning of the Plan.

OUTSIDE DIRECTORS STOCK OPTION PLAN - Page 8
<PAGE>

            (e)  NOTICE OF ADJUSTMENTS.  To the extent that the adjustments 
set forth in the foregoing paragraphs of this Section 8 relate to stock or 
securities of the Company, such adjustments, if any, shall be made by the 
Board of Directors, whose actions in that respect shall be final, binding and 
conclusive.  The Company shall give timely notice of any adjustments made to 
each holder of an Option under this Plan and such adjustments shall be 
effective and binding on the optionee.

            (f)  NON-ADJUSTABLE EVENTS.  Except as expressly provided herein, 
the adjustments provided in this Section 8 shall not be made with respect to 
any increase or decrease in the number of issued shares of Common Stock or 
other securities of the Company caused by (i) the dissolution, liquidation, 
merger, reorganization, consolidation, or spin-off of assets or stock of any 
entity other than the Company; or (ii) any issuance by the Company of shares 
of Common Stock or any other securities upon the receipt of consideration for 
such issuance.  Any such change shall not affect the number or price of 
shares of Common Stock reserved under the Plan or subject to an Option.

            (g)  RIGHT OF COMPANY TO MAKE ADJUSTMENTS.  The grant of an 
Option pursuant to the Plan shall not affect in any way the right or power of 
the Company to make adjustments, reclassifications, reorganizations, or 
changes of its capital or business structure or to merge or consolidate or to 
sell or transfer all or any part of its business or assets.

      9.    TIME OF GRANTING OPTIONS AND OPTION AGREEMENT. Neither anything 
contained in the Plan nor in any resolution adopted or to be adopted by the 
Board of Directors or the stockholders of the Company shall constitute the 
granting of any Option.  The granting of an Option shall be effected only 
when a written Option Agreement acceptable in form and substance to the Board 
of Directors, in accordance with and subject to the terms and conditions 
hereof,

OUTSIDE DIRECTORS STOCK OPTION PLAN - Page 9
<PAGE>

shall have been duly executed by the president or other duly authorized 
officer of the Company and by the person to whom such Option shall be granted 
and delivered to such person.  No person shall have any rights under the Plan 
until such time, if any, as a written Option Agreement shall have been duly 
executed and delivered as set forth in this Section 9.

      10.   NO OBLIGATION TO EXERCISE OPTION.  The granting of an Option 
shall impose no obligation upon the optionee to exercise such Option, or 
purchase any shares of Common Stock.

      11.   EFFECTIVE DATE OF THE PLAN.  The Plan shall become effective on 
September 1, 1996, (the "Effective Date"), subject to the Company's 
Registration Statement on Form S-1 with respect to the Common Stock, file 
number 333-08913, being declared effective by the Commission.  If no such 
effectiveness is obtained on or before one (1) year from the Effective Date, 
the Plan shall terminate, and all Options conditionally granted hereunder 
shall be null and void and of no force or effect.

      12.   TERMINATION OF THE PLAN.  This Plan shall terminate as of the 
expiration of ten (10) years from and after the Effective Date of the Plan or 
at such earlier time as may be determined by the Board of Directors in its 
sole discretion.  Options may be granted under this Plan at any time and from 
time to time prior to its termination.  Any Option outstanding under the Plan 
at the time of its termination shall remain in effect until the Option is 
exercised or its term expires, and the terms and conditions of the Plan shall 
survive and remain in full force and effect as to such Option.

      13.   MODIFICATION, EXTENSION, AND RENEWAL OF OPTIONS. Subject to the 
terms and conditions and within the limitations of the Plan, the Board of 
Directors may modify, extend or renew outstanding Options granted under the 
Plan, or accept the surrender of outstanding Options (to the extent not 
theretofore exercised).  The Board of Directors may, at any time prior 

OUTSIDE DIRECTORS STOCK OPTION PLAN - Page 10
<PAGE>

to the exercise of an Option when the fair market value of the Common Stock 
falls below the exercise price of the Option, modify any outstanding Option 
to specify a lower exercise price or cancel an outstanding Option and grant a 
new Option in replacement therefor at a lower exercise price, which lower 
price shall be equal to the fair market value of the Common Stock (as 
determined by the closing price of the Common Stock on the Nasdaq National 
Market) on the date of such modification or replacement.  Notwithstanding the 
foregoing, however, no modification of an Option shall, without the consent 
of the optionee, alter or impair any rights or obligations under any Option 
theretofore granted under the Plan.

      14.   AMENDMENT OF THE PLAN.  The Board of Directors may at any time 
and from time to time, without obtaining the approval of the stockholders of 
the Company, modify or amend the Plan in such respects as it shall deem 
advisable to conform to any change in the law or in any other respect.  The 
termination or any modification or amendment of the Plan shall not, without 
the consent of the person to whom any Option was previously granted, affect 
his or her rights under an Option theretofore granted to him or her.  

      15.   WITHHOLDING.  The Company may, at any time an Option is granted 
under the Plan, or at the time any Option is exercised, require the Outside 
Director receiving the grant or exercising the Option to pay any amount 
necessary to satisfy federal, state, and local withholding requirements with 
respect to such grant or exercise, such tax withholding may be satisfied at 
the Company's option by the Company withholding of Common Stock to be issued 
as a result of the exercise of the Option.  If shares of Common Stock are 
withheld, the number of shares withheld shall be equal to the dollar amount 
to be withheld divided by the closing price per share of the Common Stock on 
the Nasdaq National Market. 

OUTSIDE DIRECTORS STOCK OPTION PLAN - Page 11
<PAGE>


      The foregoing Outside Directors Stock Option Plan of Costilla Energy, 
Inc. was adopted and approved by the Board of Directors and stockholders of 
the Company on the 26th day of August, 1996.

                                COSTILLA ENERGY, INC.



                                By:
                                    -------------------------------------
                                    Michael J. Grella
                                    President and Chief Operating Officer
 
OUTSIDE DIRECTORS STOCK OPTION PLAN - Page 12


<PAGE>

                                                EXHIBIT  10.9


                      EMPLOYMENT AGREEMENT


     AGREEMENT entered into as of the 1st day of September, 1996,
between COSTILLA ENERGY, INC. (the "Company") and CADELL S.
LIEDTKE ("Liedtke"), but effective only as provided in Section 1.
below.

     In consideration of the mutual agreements herein contained,
the parties hereto agree as follows:

1.   This Agreement shall be effective, if at all, upon the
closing of the transaction contemplated by that certain
registration statement of the Company filed with the Securities
and Exchange Commission on Form S-1 (File No. 333-08913) offering
shares of Company's Common Stock to the public (the "Closing
Date"), and shall continue in effect for a three-year period from
the Closing Date (the "Initial Term"), provided however, this
Agreement will automatically renew for a period of one year, and
successive one-year periods thereafter, unless Liedtke is
notified of its termination in writing by placing such notice in
United States certified mail, return receipt requested, postage
prepaid at the address shown below, at least 90 days prior to the
stated termination date (the "Stated Termination Date) or 90 days
prior to any successive Stated Termination Dated thereafter.  If
the Closing Date shall not have occurred on or prior to December
31, 1996, this Agreement shall be of no force and effect.  This
Agreement may also be terminated by the Company because of
Liedtke's willful misconduct, negligence, inability to perform
the services required, dishonesty, breach of a fiduciary duty,
willful violation of any law, rule, regulation (other than a law,
rule or regulation relating to a traffic violation or similar
offense), or a material breach of any provision of this
Agreement, which remains uncured after 30 days' written notice to
Liedtke.

     1.   The Company may terminate Liedtke's employment
hereunder without cause, effective on the date written notice of
such termination is placed in United States certified mail,
return receipt requested, postage prepaid, addressed to Liedtke
at the address shown below.  Termination without cause will be
deemed to have occurred if the Company significantly reduces
Liedtke's duties and responsibilities in a manner inconsistent
with his experience, training and background; provided, however,
that upon any such termination, Liedtke shall be paid the greater
of the Base Salary then in effect for the remaining term of the
Agreement or one year's salary at the then Base Salary rate.  Any
vested benefits of Liedtke under any plan or agreement shall not
be affected. 

     2.   Liedtke may terminate his employment hereunder upon at
least one month's written notice to the Company placed in United
States certified mail, return receipt requested, postage prepaid
to the address shown below.  If Liedtke terminates his employment
during the first two years of this Agreement, the Company's
obligations under this Agreement shall cease immediately except
as provided below upon receipt of such notice of termination by
the Company and Liedtke 



<PAGE>

will be paid his Base Salary on a pro rata basis through the last 
day worked.  If Liedtke terminates his employment subsequent to the 
second anniversary of this Agreement, he will be paid his Base 
Salary for a one year period following his termination date.

     3.   Liedtke's title during his term of employment shall be
Chairman of the Board and Chief Executive Officer.  During the
term of this Agreement, and subject to the other provisions of
this Agreement, Liedtke shall diligently provide services to the
Company.

     4.   Liedtke agrees that this contract is one for full time
employment, that he will spend no less than 40 hours per week
(subject to legal holidays and vacations as set forth below) at
this employment.  

     5.   As compensation for the services to be rendered by
Liedtke, the Company shall pay Liedtke a Base Salary at the
annual rate of $300,000 beginning on the Closing Date.  Liedtke
shall be considered for periodic salary increases at the
discretion of the Board of Directors.  Notwithstanding the
quotation of the Base Salary at an annual rate, Liedtke will only
be paid on a pro rata basis only for the actual days worked if
his employment is terminated.

     6.   Liedtke shall be entitled to 21 days paid vacation in
each calendar year, earned pro rata each month.  Liedtke shall be
entitled to all paid holidays given by the Company to its senior
executive officers.

     7.   The Company shall reimburse Liedtke for any direct,
reasonable and necessary expenses incurred directly at the
request of the Company in the performance of this Agreement, such
expenses to generally include, but not be limited to, travel,
lodging and meals incurred while away from Midland and any other
directly attributable expenses to carrying out Liedtke's
obligations under this Agreement.

     8.   If, as a result of Liedtke's inability to perform the
essential functions of the duties set out herein, with or without
accommodation,  due to physical or mental illness or injury, and
if Liedtke shall have been absent from his duties hereunder for
more than 180 days within any 365-day period, the Company shall
be entitled to deliver written notice of termination to Liedtke
and if within 30 days after any such written notice of
termination is given, Liedtke shall not have returned to the
performance of his duties in accordance with the terms of this
Agreement, the Company may terminate his employment hereunder
upon written notice placed in United States certified mail,
return receipt requested, postage prepaid to the address shown
below.  Upon the death of Liedtke during the term of this
Agreement, the Company shall continue to pay to Liedtke's estate
the Base Salary for one year following Liedtke's death, following
which the obligations of the Company under this Agreement shall
terminate in their entirety.  Termination of Liedtke's employment
under this paragraph shall not affect Liedtke's entitlement to
any vested benefits provided herein.  


                                    -2-


<PAGE>

     9.   NONCOMPETITION; NONDISCLOSURE.

          (a)  Liedtke agrees to not engage in any Competitive
Activity for one (1) year following the date of his termination
of employment with Company, if Liedtke's employment terminates
during the Initial Term; provided, however, that this Section
10(a) shall not apply if the Company terminates Liedtke's
employment without cause.  For the purposes of this Section
10(a), "Competitive Activity" shall mean activity, without the
written consent of the Board of Directors of the Company (which
consent shall not be unreasonably withheld), consisting of
Liedtke's participation in the management of, or Liedtke's
acquisition of any interest as a director, officer, shareholder,
partner, owner or agent of, in or for any corporation,
partnership or business in competition with the Company's
Business; provided, however, that nothing in this Section 10 it
shall be construed as prohibiting Liedtke from acquiring up to,
but not more than five percent (5%) of the equity or other
interest in any such corporation, partnership or other entity. 
For purposes of this Section 10, the "Company's Business" shall
mean the exploration for, drilling and development of oil and gas
reserves in such areas as the Company is conducting such
activities on thee date of termination.

          (b)  Liedtke agrees not to disclose, either while in
the Company's employ or at any time thereafter, to any person not
employed on a full-time basis by the Company or its affiliates,
or not engaged to render services to the Company or its
affiliates, except with the prior written consent of any officer
authorized to act in the matter by the Board, any confidential
information obtained by Liedtke while in the employ of the
Company, provided, however, that this provision shall not
preclude Liedtke from the use or disclosure of information know
generally to the public or of information not considered
confidential by persons engaged in the business conducted by the
Company or from disclosure required by law or court order; and
further provided that this provision shall cease to apply if the
Company terminates Liedtke's employment without cause.  The
agreement made in this Section 10 shall be in addition to, and
not in limitation or derogation of, any obligations otherwise
imposed by law or by separate agreement upon Liedtke in respect
of confidential information of the Company.

     10.  If any action at law or equity is necessary to enforce
or interpret the terms of this Agreement, the prevailing party
shall be entitled to reasonable attorney's fees, as may be
awarded by the court, costs and necessary disbursements in
addition to any other relief to which it may be entitled.  This
provision shall be binding on the parties without regard to
whether attorney's fees would be due under statute or common law.


     11.  All notices authorized or required by the parties
hereunder shall be given in writing by United States certified
mail, return receipt requested, postage prepaid, and addressed to
the party to whom the notice is given at the addresses shown on
the signature page.  Notices shall be deemed given when deposited
in the United States mail.  Each party shall have the right to
change its addresses at any time and from time to time by giving
written notice thereof to the other.


                                    -3-


<PAGE>

     12.  This Agreement shall be construed under and in
accordance with the laws of the State of Texas. 

     13.  This Agreement shall be binding upon and inure to the
benefit of the parties hereto and their respective heirs,
executors, administrators, legal representatives, successors and
assigns where permitted by this Agreement.  However, the services
to be provided by Liedtke are personal and not performable in
satisfaction of this Agreement by any other person.

     14.  In case any one or more of the provisions contained in
this Agreement shall for any reason be held to be invalid,
illegal or unenforceable in any respect, such invalidity,
illegality or unenforceability shall not affect any other
provisions hereof, and this Agreement shall be construed as if
such invalid, illegal or unenforceable provision had never been
contained herein.

     15.  This Agreement constitutes the sole and only agreement
of the parties hereto and supersedes any prior understandings or
written or oral agreement between the parties respecting the
within subject matter.  The parties agree this contract can be
modified only in writing and that Liedtke will not rely on any
oral representations of any sort or character regarding his
employment status, salary, bonuses or benefits.

     16.  For purposes of this Agreement, notices and all other
communications provided for in this Agreement shall be in writing
and shall be deemed to have been duly given when placed in United
States certified mail, return receipt requested, postage prepaid,
addressed as follows:

          If to Liedtke:

               Cadell S. Liedtke
               900 North F Street
               Midland, Texas 79701

          If to the Company:

               Costilla Energy, Inc.
               P. O. Box 10369
               Midland, Texas  79702

               Attention:  Chairman of the Board

or to such other address as either party may have furnished to
the other in writing in accordance herewith, except that notices
of change of address shall be effective only upon receipt.



                                    -4-


<PAGE>



                                   /s/ Cadell S. Liedtke       
                                   ---------------------------------
                                   CADELL S. LIEDTKE


                                   COSTILLA ENERGY, INC.


                                   By:  /s/ Michael J. Grella  
                                        ----------------------------
                                        Michael J. Grella
                                        President

THE STATE OF TEXAS  )
COUNTY OF MIDLAND   )

     This instrument was acknowledged before me on this the ___ 
day of _____________, 1996, by CADELL S. LIEDTKE.


                                   ---------------------------------------
                                   Notary Public - State of --------------
                                   Print Name: ---------------------------
                                   My Comm. Expires: ---------------------





THE STATE OF TEXAS  )
COUNTY OF MIDLAND   )

     This instrument was acknowledged before me on this ____ day
of ___________ , 1996, by MICHAEL J. GRELLA, as President of
COSTILLA ENERGY, INC., a Delaware corporation, on behalf of said
corporation.

                                   ---------------------------------------
                                   Notary Public - State of Texas
                                   Print Name: ---------------------------
                                   My Commission Expires: ----------------




                                  -5-

<PAGE>

                                                   EXHIBIT 10.10

                      EMPLOYMENT AGREEMENT


     AGREEMENT entered into as of the 1st day of September, 1996,
between COSTILLA ENERGY, INC. (the "Company") and MICHAEL J. GRELLA
("Grella"), but effective only as provided in Section 1. below.

     In consideration of the mutual agreements herein contained,
the parties hereto agree as follows:

1.   This Agreement shall be effective, if at all, upon the
closing of the transaction contemplated by that certain
registration statement of the Company filed with the Securities
and Exchange Commission on Form S-1 (File No. 333-08913) offering
shares of Company's Common Stock to the public (the "Closing
Date"), and shall continue in effect for a three-year period from
the Closing Date (the "Initial Term"), provided however, this
Agreement will automatically renew for a period of one year, and
successive one-year periods thereafter, unless Grella is
notified of its termination in writing by placing such notice in
United States certified mail, return receipt requested, postage
prepaid at the address shown below, at least 90 days prior to the
stated termination date (the "Stated Termination Date) or 90 days
prior to any successive Stated Termination Dated thereafter.  If
the Closing Date shall not have occurred on or prior to December 31,
1996, this Agreement shall be of no force and effect.  This
Agreement may also be terminated by the Company because of
Grella's willful misconduct, negligence, inability to perform
the services required, dishonesty, breach of a fiduciary duty,
willful violation of any law, rule, regulation (other than a law,
rule or regulation relating to a traffic violation or similar
offense), or a material breach of any provision of this
Agreement, which remains uncured after 30 days' written notice to
Grella.

     1.   The Company may terminate Grella's employment
hereunder without cause, effective on the date written notice of
such termination is placed in United States certified mail,
return receipt requested, postage prepaid, addressed to Grella
at the address shown below.  Termination without cause will be
deemed to have occurred if the Company significantly reduces
Grella's duties and responsibilities in a manner inconsistent
with his experience, training and background; provided, however,
that upon any such termination, Grella shall be paid the greater
of the Base Salary then in effect for the remaining term of the
Agreement or one year's salary at the then Base Salary rate.  Any
vested benefits of Grella under any plan or agreement shall not
be affected. 

     2.   Grella may terminate his employment hereunder upon at
least one month's written notice to the Company placed in United
States certified mail, return receipt requested, postage prepaid
to the address shown below. If Grella terminates his employment
during the first two years of this Agreement, the Company's
obligations under this Agreement shall cease immediately except
as provided below upon receipt of such notice of termination by
the Company and Grella 

<PAGE>

will be paid his Base Salary on a pro rata basis through 
the last day worked.  If Grella terminates his employment 
subsequent to the second anniversary of this Agreement, 
he will be paid his Base Salary for a one year period 
following his termination date.

     3.   Grella's title during his term of employment 
shall be President and Chief Operating Officer.  During 
the term of this Agreement, and subject to the other 
provisions of this Agreement, Grella shall diligently 
provide services to the Company.

     4.   Grella agrees that this contract is one for 
full time employment, that he will spend no less than 40 
hours per week (subject to legal holidays and vacations 
as set forth below) at this employment.  

     5.   As compensation for the services to be rendered 
by Grella, the Company shall pay Grella a Base Salary at 
the annual rate of $300,000 beginning on the Closing 
Date.  Grella shall be considered for periodic salary 
increases at the discretion of the Board of Directors.  
Notwithstanding the quotation of the Base Salary at an 
annual rate, Grella will only be paid on a pro rata basis 
only for the actual days worked if his employment is 
terminated.

     6.   Grella shall be entitled to 21 days paid 
vacation in each calendar year, earned pro rata each 
month.  Grella shall be entitled to all paid holidays 
given by the Company to its senior executive officers.

     7.   The Company shall reimburse Grella for any 
direct, reasonable and necessary expenses incurred 
directly at the request of the Company in the performance 
of this Agreement, such expenses to generally include, 
but not be limited to, travel, lodging and meals incurred 
while away from Midland and any other directly 
attributable expenses to carrying out Grella's 
obligations under this Agreement.

     8.   If, as a result of Grella's inability to 
perform the essential functions of the duties set out 
herein, with or without accommodation,  due to physical 
or mental illness or injury, and if Grella shall have 
been absent from his duties hereunder for more than 180 
days within any 365-day period, the Company shall be 
entitled to deliver written notice of termination to 
Grella and if within 30 days after any such written 
notice of termination is given, Grella shall not have 
returned to the performance of his duties in accordance 
with the terms of this Agreement, the Company may 
terminate his employment hereunder upon written notice 
placed in United States certified mail, return receipt 
requested, postage prepaid to the address shown below.  
Upon the death of Grella during the term of this 
Agreement, the Company shall continue to pay to Grella's 
estate the Base Salary for one year following Grella's 
death, following which the obligations of the Company 
under this Agreement shall terminate in their entirety.  
Termination of Grella's employment under this paragraph 
shall not affect Grella's entitlement to any vested 
benefits provided herein.  

                               -2-

<PAGE>

     9.  NONCOMPETITION; NONDISCLOSURE.

          (a)  Grella agrees to not engage in any Competitive
Activity for one (1) year following the date of his termination
of employment with the Company, if Grella's employment terminates
during the Initial Term; provided, however, that this Section
10(a) shall not apply if the Company terminates Grella's
employment without cause.  For the purposes of this Section
10(a), "Competitive Activity" shall mean activity, without the
written consent of the Board of Directors of the Company (which
consent shall not be unreasonably withheld), consisting of
Grella's participation in the management of, or Grella's
acquisition of any interest as a director, officer, shareholder,
partner, owner or agent of, in or for any corporation,
partnership or business in competition with the Company's
Business; provided, however, that nothing in this Section 10 it
shall be construed as prohibiting Grella from acquiring up to,
but not more than five percent (5%) of the equity or other
interest in any such corporation, partnership or other entity. 
For purposes of this Section 10, the "Company's Business" shall
mean the exploration for, drilling and development of oil and gas
reserves in such areas as the Company is conducting such
activities on the date of termination.

          (b)  Grella agrees not to disclose, either while in
the Company's employ or at any time thereafter, to any person not
employed on a full-time basis by the Company or its affiliates,
or not engaged to render services to the Company or its
affiliates, except with the prior written consent of any officer
authorized to act in the matter by the Board, any confidential
information obtained by Grella while in the employ of the
Company, provided, however, that this provision shall not
preclude Grella from the use or disclosure of information know
generally to the public or of information not considered
confidential by persons engaged in the business conducted by the
Company or from disclosure required by law or court order; and
further provided that this provision shall cease to apply if the
Company terminates Grella's employment without cause.  The
agreement made in this Section 10 shall be in addition to, and
not in limitation or derogation of, any obligations otherwise
imposed by law or by separate agreement upon Grella in respect
of confidential information of the Company.

     10.  If any action at law or equity is necessary to enforce
or interpret the terms of this Agreement, the prevailing party
shall be entitled to reasonable attorney's fees, as may be
awarded by the court, costs and necessary disbursements in
addition to any other relief to which it may be entitled.  This
provision shall be binding on the parties without regard to
whether attorney's fees would be due under statute or common law.


     11.  All notices authorized or required by the parties
hereunder shall be given in writing by United States certified
mail, return receipt requested, postage prepaid, and addressed to
the party to whom the notice is given at the addresses shown on
the signature page.  Notices shall be deemed given when deposited
in the United States mail.  Each party shall have the right to
change its addresses at any time and from time to time by giving
written notice thereof to the other.

                               -3-

<PAGE>

     12.  This Agreement shall be construed under and in
accordance with the laws of the State of Texas. 

     13.  This Agreement shall be binding upon and inure to the
benefit of the parties hereto and their respective heirs,
executors, administrators, legal representatives, successors and
assigns where permitted by this Agreement.  However, the services
to be provided by Grella are personal and not performable in
satisfaction of this Agreement by any other person.

     14.  In case any one or more of the provisions contained in
this Agreement shall for any reason be held to be invalid,
illegal or unenforceable in any respect, such invalidity,
illegality or unenforceability shall not affect any other
provisions hereof, and this Agreement shall be construed as if
such invalid, illegal or unenforceable provision had never been
contained herein.

     15.  This Agreement constitutes the sole and only agreement
of the parties hereto and supersedes any prior understandings or
written or oral agreement between the parties respecting the
within subject matter.  The parties agree this contract can be
modified only in writing and that Grella will not rely on any
oral representations of any sort or character regarding his
employment status, salary, bonuses or benefits.

     16.  For purposes of this Agreement, notices and all other
communications provided for in this Agreement shall be in writing
and shall be deemed to have been duly given when placed in United
States certified mail, return receipt requested, postage prepaid,
addressed as follows:

          If to Grella:

               Michael J. Grella
               1 Willow Court
               Midland, Texas 79705

          If to the Company:

               Costilla Energy, Inc.
               P. O. Box 10369
               Midland, Texas  79702

               Attention:  Chairman of the Board

or to such other address as either party may have furnished to
the other in writing in accordance herewith, except that notices
of change of address shall be effective only upon receipt.

                              -4-
<PAGE>

                                        /s/ Michael J. Grella       
                                 ---------------------------------
                                          MICHAEL J. GRELLA       


                                 COSTILLA ENERGY, INC.


                                 By:    /s/ Cadell S. Liedtke  
                                     -----------------------------
                                     Cadell S. Liedtke  
                                     Chairman of the Board

THE STATE OF TEXAS   )
COUNTY OF MIDLAND    )

     This instrument was acknowledged before me on this the ___ 
day of _____________, 1996, by MICHAEL J. GRELLA.


                                   
                                 ---------------------------------
                                 Notary Public - State of --------
                                 Print Name: ---------------------
                                 My Comm. Expires: ---------------





THE STATE OF TEXAS   )
COUNTY OF MIDLAND    )

     This instrument was acknowledged before me on this ____ day
of ___________ , 1996, by CADELL S. LIEDTKE, as Chairman of the
Board of COSTILLA ENERGY, INC., a Delaware corporation, 
on behalf of said corporation.

                                                                 

                                 ---------------------------------
                                 Notary Public - State of Texas
                                 Print Name: ---------------------
                                 My Commission Expires: ---------- 
 

                               -5-

<PAGE>

                                                             EXHIBIT 10.11

                      EMPLOYMENT AGREEMENT


     AGREEMENT entered into as of the 1st day of September, 1996, between 
COSTILLA ENERGY, INC. (the "Company") and HENRY G. MUSSELMAN ("Musselman"), 
but effective only as provided in Section 1. below.

     In consideration of the mutual agreements herein contained, the parties 
hereto agree as follows:

1.   This Agreement shall be effective, if at all, upon the closing of the 
transaction contemplated by that certain registration statement of the 
Company filed with the Securities and Exchange Commission on Form S-1 (File 
No. 333-08913) offering shares of Company's Common Stock to the public (the 
"Closing Date"), and shall continue in effect for a three-year period from 
the Closing Date (the "Initial Term"), provided however, this Agreement will 
automatically renew for a period of one year, and successive one-year periods 
thereafter, unless Musselman is notified of its termination in writing by 
placing such notice in United States certified mail, return receipt 
requested, postage prepaid at the address shown below, at least 90 days prior 
to the stated termination date (the "Stated Termination Date) or 90 days 
prior to any successive Stated Termination Dated thereafter.  If the Closing 
Date shall not have occurred on or prior to December 31, 1996, this Agreement 
shall be of no force and effect.  This Agreement may also be terminated by 
the Company because of Musselman's willful misconduct, negligence, inability 
to perform the services required, dishonesty, breach of a fiduciary duty, 
willful violation of any law, rule, regulation (other than a law, rule or 
regulation relating to a traffic violation or similar offense), or a material 
breach of any provision of this Agreement, which remains uncured after 30 
days' written notice to Musselman.

     1.   The Company may terminate Musselman's employment hereunder without 
cause, effective on the date written notice of such termination is placed in 
United States certified mail, return receipt requested, postage prepaid, 
addressed to Musselman at the address shown below.  Termination without cause 
will be deemed to have occurred if the Company significantly reduces 
Musselman's duties and responsibilities in a manner inconsistent with his 
experience, training and background; provided, however, that upon any such 
termination, Musselman shall be paid the greater of the Base Salary then in 
effect for the remaining term of the Agreement or one year's salary at the 
then Base Salary rate.  Any vested benefits of Musselman under any plan or 
agreement shall not be affected. 

     2.   Musselman may terminate his employment hereunder upon
at least one month's written notice to the Company placed in
United States certified mail, return receipt requested, postage
prepaid to the address shown below.  If Musselman terminates his
employment during the first two years of this Agreement, the
Company's obligations under this Agreement shall cease
immediately except as provided below upon receipt of such notice
of termination by the Company 


                                        

<PAGE>

and Musselman will be paid his Base Salary on a pro rata basis through the 
last day worked.  If Musselman terminates his employment subsequent to the 
second anniversary of this Agreement, he will be paid his Base Salary for a 
one year period following his termination date.

     3.   Musselman's title during his term of employment shall be Executive 
Vice President.  During the term of this Agreement, and subject to the other 
provisions of this Agreement, Musselman shall diligently provide services to 
the Company.

     4.   Musselman agrees that this contract is one for full time 
employment, that he will spend no less than 40 hours per week (subject to 
legal holidays and vacations as set forth below) at this employment.  

     5.   As compensation for the services to be rendered by Musselman, the 
Company shall pay Musselman a Base Salary at the annual rate of $215,000 
beginning on the Closing Date.  Musselman shall be considered for periodic 
salary increases at the discretion of the Board of Directors.  
Notwithstanding the quotation of the Base Salary at an annual rate, Musselman 
will only be paid on a pro rata basis only for the actual days worked if his 
employment is terminated.

     6.   Musselman shall be entitled to 21 days paid vacation in each 
calendar year, earned pro rata each month.  Musselman shall be entitled to 
all paid holidays given by the Company to its senior executive officers.

     7.   The Company shall reimburse Musselman for any direct, reasonable 
and necessary expenses incurred directly at the request of the Company in the 
performance of this Agreement, such expenses to generally include, but not be 
limited to, travel, lodging and meals incurred while away from Midland and 
any other directly attributable expenses to carrying out Musselman's 
obligations under this Agreement.

     8.   If, as a result of Musselman's inability to perform the essential 
functions of the duties set out herein, with or without accommodation,  due 
to physical or mental illness or injury, and if Musselman shall have been 
absent from his duties hereunder for more than 180 days within any 365-day 
period, the Company shall be entitled to deliver written notice of 
termination to Musselman and if within 30 days after any such written notice 
of termination is given, Musselman shall not have returned to the performance 
of his duties in accordance with the terms of this Agreement, the Company may 
terminate his employment hereunder upon written notice placed in United 
States certified mail, return receipt requested, postage prepaid to the 
address shown below.  Upon the death of Musselman during the term of this 
Agreement, the Company shall continue to pay to Musselman's estate the Base 
Salary for a period of one year Musselman's death, following which the 
obligations of the Company under this Agreement shall terminate in their 
entirety.  Termination of Musselman's employment under this paragraph shall 
not affect Musselman's entitlement to any vested benefits provided herein.  


                                       -2-

<PAGE>

     9.  NONCOMPETITION; NONDISCLOSURE.

          (a)  Musselman agrees to not engage in any Competitive Activity for 
one (1) year following the date of his termination of employment with 
Company, if Musselman's employment terminates during the Initial Term; 
provided, however, that this Section 10(a) shall not apply if the Company 
terminates Musselman's employment without cause.  For the purposes of this 
Section 10(a), "Competitive Activity" shall mean activity, without the 
written consent of the Board of Directors of the Company (which consent shall 
not be unreasonably withheld), consisting of Musselman's participation in the 
management of, or Musselman's acquisition of any interest as a director, 
officer, shareholder, partner, owner or agent of, in or for any corporation, 
partnership or business in competition with the Company's Business; provided, 
however, that nothing in this Section 10 it shall be construed as prohibiting 
Musselman from acquiring up to, but not more than five percent (5%) of the 
equity or other interest in any such corporation, partnership or other 
entity. For purposes of this Section 10, the "Company's Business" shall mean 
the exploration for, drilling and development of oil and gas reserves in such 
areas as the Company is conducting such activities on thee date of 
termination.

          (b)  Musselman agrees not to disclose, either while in the 
Company's employ or at any time thereafter, to any person not employed on a 
full-time basis by the Company or its affiliates, or not engaged to render 
services to the Company or its affiliates, except with the prior written 
consent of any officer authorized to act in the matter by the Board, any 
confidential information obtained by Musselman while in the employ of the 
Company, provided, however, that this provision shall not preclude Musselman 
from the use or disclosure of information know generally to the public or of 
information not considered confidential by persons engaged in the business 
conducted by the Company or from disclosure required by law or court order; 
and further provided that this provision shall cease to apply if the Company 
terminates Musselman's employment without cause.  The agreement made in this 
Section 10 shall be in addition to, and not in limitation or derogation of, 
any obligations otherwise imposed by law or by separate agreement upon 
Musselman in respect of confidential information of the Company.

     10.  If any action at law or equity is necessary to enforce or interpret 
the terms of this Agreement, the prevailing party shall be entitled to 
reasonable attorney's fees, as may be awarded by the court, costs and 
necessary disbursements in addition to any other relief to which it may be 
entitled.  This provision shall be binding on the parties without regard to 
whether attorney's fees would be due under statute or common law.

     11.  All notices authorized or required by the parties hereunder shall 
be given in writing by United States certified mail, return receipt 
requested, postage prepaid, and addressed to the party to whom the notice is 
given at the addresses shown on the signature page.  Notices shall be deemed 
given when deposited in the United States mail.  Each party shall have the 
right to change its addresses at any time and from time to time by giving 
written notice thereof to the other.


                                       -3-

<PAGE>

     12.  This Agreement shall be construed under and in accordance with the 
laws of the State of Texas. 

     13.  This Agreement shall be binding upon and inure to the benefit of 
the parties hereto and their respective heirs, executors, administrators, 
legal representatives, successors and assigns where permitted by this 
Agreement.  However, the services to be provided by Musselman are personal 
and not performable in satisfaction of this Agreement by any other person.

     14.  In case any one or more of the provisions contained in this 
Agreement shall for any reason be held to be invalid, illegal or 
unenforceable in any respect, such invalidity, illegality or unenforceability 
shall not affect any other provisions hereof, and this Agreement shall be 
construed as if such invalid, illegal or unenforceable provision had never 
been contained herein.

     15.  This Agreement constitutes the sole and only agreement of the 
parties hereto and supersedes any prior understandings or written or oral 
agreement between the parties respecting the within subject matter.  The 
parties agree this contract can be modified only in writing and that 
Musselman will not rely on any oral representations of any sort or character 
regarding his employment status, salary, bonuses or benefits.

     16.  For purposes of this Agreement, notices and all other 
communications provided for in this Agreement shall be in writing and shall 
be deemed to have been duly given when placed in United States certified 
mail, return receipt requested, postage prepaid, addressed as follows:

          If to Musselman:

               Henry G. Musselman
               3 Deerfield Drive
               Midland, Texas 79705

          If to the Company:

               Costilla Energy, Inc.
               P. O. Box 10369
               Midland, Texas  79702

               Attention:  Chairman of the Board

or to such other address as either party may have furnished to the other in 
writing in accordance herewith, except that notices of change of address 
shall be effective only upon receipt.


                                       -4-

<PAGE>

                                     /s/ Henry G. Musselman       
                                   ---------------------------------------
                                   HENRY G. MUSSELMAN


                                   COSTILLA ENERGY, INC.


                                   By:    /s/ Cadell S. Liedtke   
                                   ---------------------------------------
                                           Cadell S. Liedtke
                                           Chairman of the Board

THE STATE OF TEXAS   )
COUNTY OF MIDLAND    )

     This instrument was acknowledged before me on this the ______  day of 
_____________, 1996, by HENRY G. MUSSELMAN.

                                   ---------------------------------------
                                   Notary Public - State of --------------
                                   Print Name: ---------------------------
                                   My Comm. Expires: ---------------------



THE STATE OF TEXAS   )
COUNTY OF MIDLAND    )

     This instrument was acknowledged before me on this ____ day of 
____________ , 1996, by CADELL S. LIEDTKE, as Chairman of the Board of 
COSTILLA ENERGY, INC., a Delaware corporation, on behalf of said corporation.



                                   ---------------------------------------
                                   Notary Public - State of Texas
                                   Print Name: ---------------------------
                                   My Commission Expires: ----------------

                                       -5-



<PAGE>




                             PURCHASE AND SALE AGREEMENT

                                    by and between

                          PARKER & PARSLEY DEVELOPMENT L.P.

                                         and

                           PARKER & PARSLEY PRODUCING L.P.

                                      as Seller

                                         and

                            COSTILLA PETROLEUM CORPORATION

                                         and

                               COSTILLA ENERGY, L.L.C.

                                     as Purchaser



                                    APRIL 3, 1995


<PAGE>


                             PURCHASE AND SALE AGREEMENT

    This PURCHASE AND SALE AGREEMENT (this "AGREEMENT") is made as of April 3,
1995, by and between PARKER & PARSLEY DEVELOPMENT L.P., a Texas limited
partnership (for itself individually and as the successor by merger with Parker
& Parsley Development Company and P&P Producing, Inc. ("PPDLP"), and PARKER &
PARSLEY PRODUCING L.P., a Delaware limited partnership f/k/a Bridge Oil Company,
L.P. ("PPPLP", and, together with PPDLP, "SELLER"), and COSTILLA PETROLEUM
CORPORATION, a Texas corporation ("CPC") and COSTILLA ENERGY, L.L.C., a Texas
limited liability company ("CELLC", and, together with CPC, "PURCHASER").


                                      RECITALS:

    WHEREAS, on or about April 3, 1995, Seller and Purchaser entered into a
Purchase and Sale Agreement whereby Seller agreed to sell and Purchaser agreed
to purchase Seller's interests in certain oil and gas leases, agreements,
contracts, real property, personal property, equipment and related rights (the
"PRIOR AGREEMENT"); and

    WHEREAS, Seller and Purchaser now desire to amend and restate the Prior
Agreement as this Agreement.

    NOW, THEREFORE, for good and valuable consideration and for the mutual
covenants contained herein, Seller and Purchaser hereby agree as follows:


                            ARTICLE 1.  SALE AND PURCHASE

    1.1  EFFECTIVE TIME.  The effective time and date of the purchase and sale
contemplated hereby shall be 7:00 a.m., April 1, 1995, at the site of the
respective Subject Properties (the "EFFECTIVE TIME").

    1.2  SALE AND PURCHASE.  Subject to the terms and conditions herein
contained, at Closing and as of the Effective Time, Seller shall sell, assign,
transfer and convey to Purchaser,  and Purchaser shall purchase and receive, the
following described assets, less and except the Excluded Assets (the "ASSETS"):

    (a)  all interest of Seller as of the Effective Time (the "SALE INTEREST")
         in and to (i) the wells, leases and/or units described in Exhibit "A"
         attached hereto and incorporated herein, (ii) the oil, gas and mineral
         leasehold estates and fee estates appurtenant to wells, leases and/or
         units described in Exhibit "A" attached hereto, upon which such wells
         are located or with respect to which such wells are associated, and
         (iii) all other interests in oil, gas and other minerals of whatever
         nature appurtenant to wells, leases and/or units described in Exhibit
         "A" attached hereto, including, without limitation, all fee estates,
         fee mineral and royalty interests, working interests, farmout rights
         and overriding royalty interests (reference being hereby made to
         Seller's records and files located at 303 W. Wall, Suite 101, Midland,
         Texas, for a more complete description of said leases, leasehold and
         fee estates and interests), together with all of Seller's right, title
         and interest in respect of and in any pooled, communitized or unitized
         acreage of which any such leasehold, fee or other interest is a part
         and all of the rights incident thereto (the "SUBJECT PROPERTIES");


                                          1

<PAGE>

    (b)  to the extent attributable or allocable to the Subject Properties, all
         interest of Seller (including, without limitation, leasehold) as of
         the Effective Time in and to: (i) all wells (including but not limited
         to the wells described in Exhibit "A" and all other oil, gas,
         injection and water wells), equipment, lease equipment, signage,
         gathering pipelines, gas facilities, gathering systems, gathering,
         storage, distribution, treating, processing and disposal facilities
         and tanks, vehicles, tools, buildings, inventory and all other real or
         tangible personal property and fixtures which are located on or
         directly and solely related to the Subject Properties, including,
         without limitation, items of personal property described in Exhibit
         "A-1"; (ii) all oil, gas, mineral and other hydrocarbon substances
         produced on or after the Effective Time; (iii) to the extent the same
         are assignable or transferable by Seller, all orders, contracts, title
         opinions and documents, abstracts of title, leases, deeds, unitization
         agreements, pooling agreements, operating agreements, division of
         interest statements, participation agreements, and all other
         agreements and instruments; (iv) all surface leasehold and fee
         estates, easements, rights-of-way, licenses, authorizations, permits
         and similar rights and interests, subject to the rights of third
         parties; (v) except as expressly provided otherwise herein, all
         warranties, covenants, indemnities  and representations from third
         parties, and all claims, rights and causes of action against third
         parties, asserted and unasserted, known and unknown; (vi) to the
         extent assignable and subject to the rights of third parties, lease
         files, land files, operating files, well files, oil and gas sales
         contract files, gas processing files, logs, test data, production
         histories, division order files, abstracts, title files and materials,
         and all other books, files and records (the "RECORDS"), and all rights
         thereto, subject to the rights of third parties; and (vii) all other
         rights, privileges, benefits and powers conferred upon the owner and
         holder of interests in the Subject Properties; and

    (c)  to the extent necessary for the ownership, use or development of the
         Subject Properties and subject to the rights of third parties, the
         right of ingress and egress with respect to the SF Interests (as
         defined below).

    1.3  EXCLUDED ASSETS.  Notwithstanding anything in this Agreement to the
contrary, the Assets do not include and Purchaser agrees and acknowledges that
each Seller respectively  has reserved from the Assets and hereby reserves unto
itself any and all rights, titles and interests in and to (a) (1) fee, fee
mineral and royalty interests which were conveyed to PPPLP by all or any of
Santa Fe Energy Resources, Inc. ("SFER"), Santa Fe Energy Operating Partners,
L.P. ("SFEOP") or SFER Properties-A, Inc. ("SFERP-A") or any of their respective
Affiliates, and (2) or arising under that certain Exploration Agreement dated
April 8, 1994, between SFEOP and PPPLP and all property rights, grants, and
interests created, made or evidenced by such Exploration Agreement
(collectively, the "SF INTERESTS"), (b) the right of ingress and egress for the
purpose of mining, drilling, exploring, operating, holding, producing and
developing the SF Interests for oil, gas, minerals and other hydrocarbon
substances, and (c) seismic, geologic and geophysical records and data not
expressly described in Section 1.2(b)(vi) above ((a) through (c), collectively,
the "EXCLUDED ASSETS").


                              ARTICLE 2.  CONSIDERATION

    2.1  CONSIDERATION.   As consideration for this Agreement and the transfer
of the Assets, at Closing, Purchaser shall pay to Seller $53,578,954 (the
"PURCHASE PRICE"), as may be  adjusted pursuant hereto (the "ADJUSTED PURCHASE
PRICE").  The Purchase Price has been allocated by Purchaser as provided on
Exhibit "A".


                                          2

<PAGE>

    2.2  MANNER OF PAYMENT.  At Closing, except as provided in the following
Section 2.3, Purchaser shall pay Seller or Seller's designee the Adjusted
Purchase Price by wire transfer of immediately available funds as follows:

                   Account:            Parker & Parsley Development L.P.
                   Account No:         1290288845
                                       NationsBank of Texas, N.A.
                   ABA Routing No:     111000025
                   Attention:          Frank Stowers
                                       NationsBank of Texas-Midland
                                       (915) 685-2179

    2.3  LIKE KIND EXCHANGE OPTION.  Seller and Purchaser hereby agree that
Seller, in lieu of the sale of the Assets to Purchaser for the cash
consideration provided herein, shall have the right at any time prior to Closing
to assign all or a portion of its rights under this Agreement to a qualified
intermediary in order to accomplish the transactions contemplated hereby in a
manner that will comply, either in whole or in part, with the requirements of a
like kind exchange pursuant to Section 1031 of the Internal Revenue Code of
1986, as amended ("CODE").  In the event Seller assigns its rights under this
Agreement pursuant to this Section 2.3, Seller agrees to notify Purchaser in
writing of such assignment before Closing.  If Seller assigns its rights under
this Agreement, Purchaser agrees to (i) consent to Seller's assignment of its
rights in this Agreement, (ii) deposit the Adjusted Purchase Price with the
qualified escrow or qualified trust account designated by Seller at Closing, and
(iii) take such further actions, at Seller's cost, as are reasonably required to
effectuate the transactions contemplated hereby pursuant to Code Section 1031,
but, in so acting, Purchaser shall have no liability to any party in connection
with such actions.  All risks associated with any like kind exchange and
compliance thereof with applicable laws, rules and regulations shall be the sole
responsibility of Seller, and Seller agrees to indemnify and hold Purchaser
harmless from and against all costs, expenses, liabilities and obligations which
arise as a result of Purchaser's agreement contained in this Section 2.3.

    2.4  DEPOSIT.  Contemporaneously with the execution of this Agreement,
Purchaser will pay to Seller $1,600,000, which shall be wired in accordance with
the instructions contained in Section 2.2 above.  If Closing occurs, such amount
and all interest accrued thereon (the "DEPOSIT")  shall be applied to reduce the
Adjusted Purchase Price.  If Closing does not occur, the Deposit shall be
applied as provided in Section 10.2.  Until disposed of in accordance with the
terms of this Agreement, the Deposit shall be held and invested by Seller in
marketable obligations issued or unconditionally guaranteed by the United States
of America or an instrumentality or agency thereof and entitled to the full
faith and credit of the United States of America, or in money market and/or
mutual funds that invest solely in such obligations.

                                 ARTICLE 3.  DEFECTS

    3.1  DEFINITION OF ACCEPTABLE TITLE.  As used herein, the term 
"ACCEPTABLE TITLE" shall mean, as to the Subject Properties, such right, 
title and interest that (a) entitles Seller to receive not less than the net 
revenue interest set forth in Exhibit "A" of all oil, gas and associated 
liquid and gaseous hydrocarbons produced, saved and marketed from the 
respective Subject Properties, (b) obligates Seller to bear costs and 
expenses relating to the maintenance, development, and operation of all wells 
located on the respective Subject Properties in an amount not greater than 
the working interest set forth in Exhibit "A", unless there is a 
corresponding increase in the applicable net revenue interest, and (c) except 
for Permitted Encumbrances, is free and clear of all liens, claims and 
encumbrances; PROVIDED, however that (i) the presence of a preferential right 
to purchase provision shall not be considered to be a Defect (as defined in 
Section 3.5 below); and (ii) if Purchaser demonstrates before or after 
Closing, subject to Section 13.12 below, that Seller does not have or cannot 
convey

                                          3

<PAGE>

Acceptable Title to a well described in Exhibit "A" and, if so demonstrated
after Closing, that Purchaser did not receive at Closing an adjustment to the
Purchase Price or other consideration on account of such matter, and if Seller
owns fee mineral interests or other interests underlying the applicable
proration or spacing unit on which such well is located, Seller shall resolve
such matter by, at Seller's option, either (1) granting a lease (on mutually
acceptable terms) on all or part of such interests, or (2) conveying (which
conveyance may be limited in term, similar to an oil and gas lease) all or part
of such interests to Purchaser and, if so resolved, such matter shall not be
considered a Defect for any purpose hereunder if the interest so conveyed, or
leased, will (after considering, in the case of a lease, the royalty reserved to
Seller under the lease) be sufficient so that, after giving effect thereto, such
matter will no longer exist (a "FURTHER CONVEYANCE"); PROVIDED, however, that
such Further Conveyance shall be limited to depths from the surface of the
ground down to the deepest producing zone from which production is being
obtained (from the subject well) at the Effective Time insofar as such depths
underlie the proration or spacing unit attributable to such well. Purchaser
acknowledges and agrees that any net revenue interests and working interests
reflected on Exhibit "A" are for the convenience of Seller and Purchaser and
included solely for the purpose of determining Acceptable Title prior to
Closing; Seller does not and shall not represent or warrant that the Sale
Interest is equal to any such interests in any respect, but agrees that (i) for
purposes of determining Defects prior to Closing, with respect to those Subject
Properties listed on Exhibit "A" with "0.0000" "APO" interests, the "APO"
interests shall be deemed to be the same as the corresponding "BPO" interests,
and (ii) Purchaser may assert as a Title Defect (as defined in and pursuant to
Section 3.5 below) any matter reasonably expected to reduce the net revenue
interest assigned to such Subject Property or any matter reasonably expected to
increase the working interest assigned to such Subject Property unless there is
a corresponding increase in the applicable net revenue interest.

    3.2  DEFINITION OF PERMITTED ENCUMBRANCES.  As used herein, the term
"PERMITTED ENCUMBRANCES" shall mean the following items, provided none of the
following items shall operate to increase the working interest of Seller as set
forth in Exhibit "A" for any of the Subject Properties, without a corresponding
increase in the applicable net revenue interest, or decrease the net revenue
interest of Seller set forth in Exhibit "A" for any of the Subject Properties:

    (a)  lessors' royalties, overriding royalties, production payments,
         reversionary interests and similar burdens;

    (b)  division orders and sales contracts;

    (c)  preferential rights to purchase not identified in writing to Seller
         pursuant to Section 3.7 below, or, if so identified, with respect to
         which (i) waivers are obtained from the appropriate parties, (ii) the
         appropriate time period for asserting such rights has expired without
         an exercise of such rights, or (iii) appropriate parties have
         exercised such rights and the Purchase Price has been adjusted where
         appropriate with reference to the value allocated in Exhibit  "A" to
         the affected Asset ("PREFERENTIAL RIGHTS");

    (d)  rights to consent to assignments required by this Agreement held by
         Persons other than governmental entities and not identified in writing
         to Seller pursuant to Section 3.7 below, or, if so identified, with
         respect to which (i) waivers or consents are obtained from the
         appropriate parties, or (ii) the prescribed time period for denying
         such consent has expired;


                                          4

<PAGE>

    (e)  materialman's, mechanic's, repairman's, employee's, contractor's,
         operator's, tax, and other similar liens or charges arising in the
         ordinary course of business for obligations that are not delinquent
         and that will be paid and discharged in the ordinary course of
         business;

    (f)  rights to consent by, required notices to, filings with, or other
         actions by governmental entities in connection with the sale or
         conveyance of oil and gas leasehold and fee estates or interests
         therein, which consents, notices, filings and/or other actions are
         customarily obtained after closing;

    (g)  easements, rights-of-way, servitudes, permits, surface leases and
         other rights in respect of surface operations affecting the Assets
         which in the aggregate are not such as to interfere materially with
         the operation or use of any of the Subject Properties or materially
         reduce the value thereof;

    (h)  rights reserved to or vested in any governmental, statutory or public
         authority to control or regulate any of the Assets in any manner, and
         all applicable laws, rules and orders of any governmental authority
         affecting the Assets which in the aggregate are not such as to
         interfere materially with the operation or use of any  of the Subject
         Properties or materially reduce the value thereof;

    (i)  operating agreements, unit agreements, unit operating agreements,
         pooling agreements and pooling designations affecting the Subject
         Properties which are of public record or contained in the Records or
         otherwise available to Purchaser and all actions taken or operations
         occurring in the normal course of business pursuant to such
         instruments;

    (j)  Title Defects that Purchaser may have expressly waived in writing or
         which are deemed to have been waived pursuant to Section 3.6;

    (k)  all conveyances, reservations and exceptions of public record or
         contained  in the Records affecting the Assets which in the aggregate
         are not such as to interfere materially with the operation or use of
         any of the Subject Properties or materially reduce the value thereof;
         and

    (l)  all other liens, charges, encumbrances, contracts, agreements,
         instruments, obligations, defects and irregularities affecting the
         Assets which in the aggregate are not such as to interfere materially
         with the operation or use of the affected Subject Properties or
         materially reduce the value thereof.

    3.3  ENVIRONMENTAL AND PHYSICAL ASSESSMENT.   Purchaser shall have the
right to make an environmental and other physical assessment of the Assets
during the period ("EXAMINATION PERIOD") beginning on the date of execution of
this Agreement and ending on June 1, 1995.  During Seller's normal business
hours, Purchaser and its Representatives shall have the right to enter upon the
Assets and all buildings and improvements thereon, inspect the same, conduct
soil and water tests and borings, and generally conduct such tests,
examinations, investigations and studies as may be reasonably necessary or
appropriate for the preparation of appropriate environmental and other reports
relating to the Assets, their condition, and the presence of wastes or
contaminants.  Seller shall be provided 48 hours prior notice of  such
activities and shall have the right to witness all such tests and
investigations.  Purchaser shall keep any data or information acquired by all
such examinations and the results of all analyses of such data and information
strictly confidential and not disclose any of the same to any Person unless
otherwise required by law or regulation and then only after written notice to
Seller of the need for disclosure and the identity of all intended recipients.
Seller hereby grants


                                          5

<PAGE>
Purchaser access to the Assets to conduct its environmental and other physical
assessment upon the condition that, in accordance with Section 9.2, Purchaser
hereby indemnifies and holds Seller and its Affiliates and their respective
Representatives harmless from and against any and all claims for or related to
personal injury or property damage arising out of or as a result of the
activities of Purchaser or its Representatives on the Assets in conducting such
environmental and physical assessments.  If during the Examination Period,
Purchaser determines in good faith that (i) there is a condition or circumstance
which constitutes a violation of applicable law or regulation, or (ii) there is
a claim, demand, filing, investigation, action, suit or other legal or
administrative proceeding asserted or otherwise initiated by a governmental
authority and arising from or related to the Subject Properties or the ownership
or operation of any thereof ("ENVIRONMENTAL DEFECT"), Purchaser may include
notice of such Defect in any Notice of Defects delivered hereunder, and the
value of  such Defect asserted by Purchaser shall not be limited to the value of
the Subject Properties so affected; PROVIDED, that any such matter not included
in a Notice of Defects shall be waived by Purchaser.

    3.4  IDENTIFIED CLAIMS.  During the Examination Period and in accordance
with Section 4.12, Seller shall make available to Purchaser for examination and
copying (at Purchaser's cost) any of the Records and Seller's accounting records
relating to the Assets as Purchaser may reasonably request.  Seller shall also
permit Purchaser's Representatives to consult with Seller's employees and
Seller's independent contractors who have knowledge concerning the Assets during
normal business hours regarding such records; PROVIDED, that such consultation
shall not unreasonably disrupt the performance by such employee or independent
contractor of his or its duties with Seller.  If during the Examination Period,
Purchaser determines in good faith that (i) royalties, rentals or other payments
due in respect of the Assets prior to the Effective Time have not been paid
(except for those amounts in suspense), or (ii) there are unsatisfied claims,
demands, liabilities or obligations in respect of the Assets based upon
omissions, events or occurrences prior to the Effective Time (collectively,
"IDENTIFIED CLAIMS"), Purchaser may include notice of such Identified Claims in
any Notice of Defects delivered hereunder; PROVIDED, that any such matter not
included in a Notice of Defects shall be waived by Purchaser.

    3.5  NOTICE OF DEFECTS.  If any matter is discovered by Purchaser that, in
Purchaser's reasonable, good faith opinion, would (a) cause any of the Sale
Interest not to be Acceptable Title (a "TITLE DEFECT"); (b) constitute a breach
of Seller's representations, warranties and agreements contained herein (a
"CONTRACT DEFECT"); (c) constitute an Environmental Defect; or (d) constitute an
Identified Claim ((a) through (d) individually, a "DEFECT", and collectively,
the "DEFECTS"), then Purchaser may provide written notice (a "NOTICE OF
DEFECTS") thereof actually delivered to Seller not later than noon, June 2,
1995; PROVIDED, however, that any notice concerning a Contract Defect not
discoverable from an examination of the Records, public records, Purchaser's
records, the records of any purchaser of production attributable to the Subject
Properties or a physical inspection of the Assets may be delivered to Seller on
or before noon of the business day immediately before the Closing Date, and
that, if so delivered, Purchaser's sole remedy therefor shall be as provided in
Section 3.6, with the procedure therein provided applicable thereto the same as
if such Contract Defect had been included in any Notice of Defects delivered not
later than noon, June 2, 1995 (i.e., the value of any such Contract Defect shall
be included in the value of any other Defects included in a Notice of Defects,
or, if no Notice of Defects has been provided, then such Contract Defect only
may be included in a Notice of Defects then given to Seller). A Notice of
Defects shall specifically identify the Defect and include (i) the Purchaser's
purported value of each specific Defect, (ii) an identification of each affected
Asset, (iii) Purchaser's basis for determining the existence and value of such
Defect, together with all associated reports, opinions, data, valuations,
assessments, conclusions and supporting calculations, and (iv) Purchaser's
statement of steps necessary to cure each such Defect to its satisfaction, all
of which shall be kept strictly confidential by Seller, except to the extent
required by law, regulation or order of any court or other governmental
authority or as may be necessary to address Defects identified in a Notice of
Defects.


                                          6

<PAGE>

    3.6  REMEDY FOR DEFECTS.  In Seller's sole discretion, but without
obligation, it may, at its sole cost, take such steps as are reasonably
necessary to cure Defects identified in a Notice of Defects.  In the event
Seller is unable or elects not to cure any or all Defects, Seller and Purchaser
may, at Seller's option, meet and use their best efforts to agree in good faith
on the validity of each Defect claim and the need for and amount of any mutually
acceptable Purchase Price adjustment.  Purchaser's asserted Title Defect
adjustments shall be made with reference (as a maximum) to the allocated value
for each affected Asset as set forth in Exhibit "A".  If the parties cannot
agree on the need for or the amount of a claimed Purchase Price adjustment,
Purchaser shall accept and purchase the Assets, including any Asset subject to a
Defect, as provided herein; PROVIDED, however, that (i) if the aggregate net
amount of Purchase Price adjustments asserted by Purchaser, PLUS the amount of
any uninsured Casualty Losses and Casualty Losses not fully covered by insurance
(to the extent of such deficiency only), PLUS the value of any of the Subject
Properties (with reference to the allocated value thereof on Exhibit "A" as a
maximum) taken in condemnation or under the right of eminent domain prior to the
end of the Examination Period, or with respect to which proceedings for such
purposes shall be pending or threatened in writing at such time, equals or
exceeds $3,500,000, or (ii) if the aggregate value of Preferential Rights to be
exercised at Closing equals or exceeds 30% of the Purchase Price, then Seller or
Purchaser may, upon written notice to the other, terminate this Agreement,
without liability or further obligation to the other party, subject to Section
10.2. Seller shall have no obligation hereunder to any Person to sell, convey,
deliver or otherwise transfer all or any part of the Assets if Purchaser or
Seller terminates this Agreement pursuant to the foregoing clause (ii).
Purchaser agrees and acknowledges that Seller has no obligation to adjust the
Purchase Price with respect to Defects.  If Closing occurs, Purchaser shall be
deemed to have waived or assumed any and all claims, known and unknown, arising
from or related to any and all Defects or title to or other condition of the
Assets, including, without limitation, whether or not identified in a Notice of
Defects, and notwithstanding the fact that Seller may not have cured any such
Defect(s) to Purchaser's satisfaction, and Seller shall have no obligation with
respect thereto.  As used in this Agreement, the "AGGREGATE NET AMOUNT"  of
Purchase Price adjustments shall be determined by subtracting from the value of
all Defects asserted by Purchaser (i) the value of all interests by which
Seller's actual interests in the Subject Properties exceeds the net revenue
interests set forth on Exhibit  "A" hereto, and (ii) the value of Defects
asserted by Purchaser which are cured or otherwise resolved to Purchaser's
reasonable satisfaction.  If Purchaser provides Seller with a Notice of Defects,
Purchaser shall provide Seller copies of all pertinent portions of applicable
title opinions, data and curative information available to it to enable the
parties to make such determination.

    3.7  PREFERENTIAL PURCHASE RIGHTS AND CONSENTS TO ASSIGN.  Upon written
notification to Seller by Purchaser identifying Persons (and their addresses)
holding preferential rights to purchase affecting the Subject Properties or the
right to consent with respect to any assignments required hereby, other than
such consents of governmental authorities which are usually obtained in the
normal course of business after Closing, actually received by Seller not later
than the earlier of (i) fifteen (15) days prior to the Closing Date, or (ii)
five (5) business days prior to the latest date prior to Closing permitted by
the subject agreement for such notice to be provided,  Seller shall send notice
of this Agreement to all such Persons (y) offering to sell to each such Person
the Subject Properties for which a preferential right is held on and subject to
the terms hereof and for the same allocated value for such Subject Properties
reflected on Exhibit "A", or (z) requesting, where appropriate, consent to any
assignment required in connection herewith.  Purchaser shall be entitled to
review and approve the form of all such notices; PROVIDED, that such approval
shall not be unreasonably withheld or delayed.  If, prior to Closing, any of
such Persons asserting a preferential purchase right notifies Seller that it
intends to consummate the purchase of the Subject Properties to which it holds a
preferential



                                          7

<PAGE>

purchase right pursuant to the terms and conditions hereof, then, subject to
clause (ii) of Section 3.6 above, such Subject Properties shall be excluded from
the Assets to be conveyed to Purchaser under this Agreement and the Purchase
Price shall be reduced by the allocated value of such Subject Properties
reflected in Exhibit "A"; PROVIDED, however, that if the holder of such
preferential right fails to consummate the purchase of such Subject Properties
on the Closing Date, then Seller shall promptly so notify Purchaser, and Seller
shall sell immediately to Purchaser, and Purchaser shall purchase from Seller,
for a price equal to the allocated value of such Subject Properties and upon the
other terms of this Agreement, the Subject Properties to which the preferential
purchase right was asserted. All Subject Properties for which a preferential
purchase right has not been asserted prior to Closing by the holder of such
right, or with respect to which Closing does not occur on the Closing Date
following the assertion of a preferential purchase right, shall be sold to
Purchaser at Closing pursuant and subject to the provisions of this Agreement.
If one (1) or more of the holders of any preferential purchase rights notifies
Seller subsequent to Closing that it intends to assert its preferential purchase
right, Seller shall give notice thereof to Purchaser, whereupon Purchaser shall
satisfy all such preferential purchase right obligations of Seller to such
holders and shall indemnify and hold Seller harmless from and against any and
all claims, liabilities, losses, costs and expenses (including, without
limitation, court costs and reasonable attorneys' fees) in connection therewith,
and Purchaser shall be entitled to receive (and Seller hereby assigns to
Purchaser all of Seller's rights to) all proceeds received from such holders in
connection with such preferential purchase rights;  Purchaser shall indemnify
and hold harmless Seller from and against any and all claims, liabilities,
losses, costs and expenses (including, without limitation, court costs and
reasonable attorneys' fees) asserted or incurred at any time (whether before or
after Closing) with respect to or arising directly or indirectly from the claims
of any Person to a preferential purchase right affecting any of the Assets
transferred to Purchaser hereunder.


            ARTICLE 4.  SELLER'S REPRESENTATIONS,WARRANTIES AND COVENANTS

    Seller represents, warrants to and covenants with Purchaser that (PROVIDED,
that each of PPDLP and PPPLP, respectively, makes such representations,
warranties and covenants solely with respect to itself and not as to the other):

    4.1  EXISTENCE.  PPDLP and PPPLP are limited partnerships, duly formed,
validly existing and in good standing under the laws of the State of Texas and
the State of Delaware, respectively.

    4.2  POWER.  Seller has the requisite power and authority to enter into and
perform this Agreement and the transactions contemplated hereby. The execution,
delivery and performance of this Agreement by Seller, and the transactions
contemplated hereby, will not (a) violate any provision of Seller's articles or
agreement of limited partnership or other governing documents, (b) conflict
with, result in a breach of, constitute a default (or an event that with the
lapse of time or notice, or both would constitute a default) under any agreement
or instrument to which Seller is a party or by which Seller is bound, (c) to the
best knowledge and belief of Seller,


                                          8

<PAGE>

violate any judgment, order, ruling, or decree applicable to Seller and entered
or delivered in a proceeding in which Seller was or is a named party, or (d) to
the best knowledge and belief of Seller, violate any applicable law, rule or
regulation.

    4.3  AUTHORIZATION.   The execution, delivery and performance of this
Agreement and the transactions contemplated hereby have been duly and validly
authorized by all requisite action on the part of Seller.  This Agreement has
been duly executed and delivered on behalf of Seller, and at the Closing all
documents and instruments required hereunder to be executed and delivered by
Seller shall be duly executed and delivered.  This Agreement and such documents
and instruments shall constitute legal, valid and binding obligations of  Seller
enforceable in accordance with their terms subject, however, to the effect of
bankruptcy, insolvency, reorganization, moratorium and similar laws from time to
time in effect relating to the rights and remedies of creditors, as well as to
general principles of equity (regardless of whether such enforceability is
considered in a proceeding in equity or at law).

    4.4  BROKERS.  Seller has incurred no obligation or liability, contingent
or otherwise, for brokers' or finders' fees in respect of the matters provided
for in this Agreement which will be the responsibility of Purchaser, and any
such obligation or liability that might exist shall be the sole obligation of
Seller.

    4.5  FOREIGN PERSON.   Seller is not a "FOREIGN PERSON" within the meaning
of the Code.

    4.6  NO LIENS.  The Assets are not subject to any valid and enforceable
security interests, liens or mortgages.

    4.7  VALID AGREEMENTS.  Material oil and gas leases and other material
contracts and agreements constituting a part of the Assets are valid and in full
force and effect, and Seller is not, or with the lapse of time or giving of
notice or both will not be, in material breach or material default, with respect
to any of its obligations thereunder and no party has given or threatened to
give Seller notice of any material default thereunder.

    4.8  NO RESERVATIONS.  There are no reservations which affect the Assets
other than those currently of public record.

    4.9  PERMITS.  Seller possesses all material licenses, permits,
certificates, orders, approvals and authorizations necessary to own the Assets
and to carry on its business as now being conducted.

    4.10 COMPLIANCE WITH LAW.  Seller is in material compliance with all laws,
ordinances, rules, regulations and orders applicable to the Assets, including,
without limitation, all environmental laws, ordinances, rules, regulations and
orders, except to the extent of any non-compliance that is not reasonably
expected to result in a material adverse affect on the Assets; however, Seller
has not received any notice of any claimed noncompliance therewith.  Seller is


                                          9

<PAGE>

not aware of any facts, conditions or circumstances in connection with, related
to or associated with the Assets that could reasonably be expected to give rise
to any claim or assertion that Seller, the Assets or the ownership or operation
of any thereof is not in material compliance with any applicable law, rule,
regulation, ordinance, or order of any governmental authority or with any term
or conditions of any applicable permit, license, approval, consent, certificate
or other authorization.

    4.11 TAXES.  All ad valorem, property, production, severance, excise, and
similar taxes and assessments based on or measured by the ownership of property
or the production of hydrocarbons or the receipt of proceeds therefrom
attributable to the Assets that have become due and payable have been properly
and timely paid, except to the extent of any failure that is not reasonably
expected to result in a material adverse effect on the Assets.

    4.12 ACCESS TO RECORDS.  Seller will provide Purchaser through Closing
access to the Records during normal business hours at their place of storage,
and, at Purchaser's cost, will assist Purchaser in obtaining access to and the
right to review and copy Records pertaining to the Subject Properties not in
Seller's possession or control.  From and after the date of the execution of
this Agreement through the Closing Date, Seller shall not add to or remove from
the Records any contracts, instruments, documents or other materials except for
such additions and removals as are done in the ordinary course of business with
respect to ongoing operations.

    4.13 NO CALL.  No Person has any option to purchase or similar right under
any agreement with respect to production attributable to the Assets which could
reasonably be expected to materially and adversely affect the value of  the
Assets, taken as a whole.

    4.14 LITIGATION.  No pending litigation or other proceeding in which Seller
(or its direct predecessor in title) is a named party affects any of the Assets,
and no litigation or other proceeding has been threatened in writing with
respect to any of the Assets, except as described in the Disclosure Schedule
attached hereto.

    4.15 NO "TAKE-OR-PAY" COMMITMENTS.  Seller is not obligated by virtue of a
prepayment arrangement, a "take-or-pay" arrangement, a production payment or any
other arrangement to deliver hydrocarbons from the Subject Properties at some
future time without then or thereafter receiving full payment therefor.

    4.16 ROYALTIES.  All royalties, rentals and other payments due with respect
to the Assets have been properly and timely paid.

    4.17 ACCESS.  No condition exists upon any of the Subject Properties which
is reasonably expected to restrict access thereto.


                                          10

<PAGE>

             LIMITATION AND DISCLAIMER OF REPRESENTATIONS AND WARRANTIES

THE EXPRESS REPRESENTATIONS AND WARRANTIES OF SELLER CONTAINED IN THIS AGREEMENT
ARE EXCLUSIVE AND ARE IN LIEU OF ALL OTHER REPRESENTATIONS AND WARRANTIES,
EXPRESS, IMPLIED, STATUTORY, OR OTHERWISE, AND, EXCEPT FOR THE REPRESENTATIONS
AND WARRANTIES CONTAINED IN SECTIONS 4.1 THROUGH 4.5 (WHICH SHALL SURVIVE
CLOSING) THE REPRESENTATIONS AND WARRANTIES CONTAINED HEREIN SHALL TERMINATE IN
ALL RESPECTS UPON CLOSING.  ANY ASSIGNMENT AND BILL OF SALE OR OTHER CONVEYANCE
EXECUTED AND DELIVERED PURSUANT HERETO SHALL BE: (a) WITHOUT ANY WARRANTY OR
REPRESENTATION OF TITLE, EITHER EXPRESS, IMPLIED, STATUTORY OR OTHERWISE; (b)
WITHOUT ANY EXPRESS, IMPLIED, STATUTORY OR OTHER WARRANTY OR REPRESENTATION AS
TO THE CONDITION, QUANTITY, QUALITY, FITNESS FOR A PARTICULAR PURPOSE,
CONFORMITY TO MODELS OR SAMPLES OF MATERIALS OR MERCHANTABILITY OF ANY OF THE
ASSETS OR THEIR FITNESS FOR ANY PURPOSE; AND (c) WITHOUT ANY OTHER EXPRESS,
IMPLIED, STATUTORY OR OTHER WARRANTY OR REPRESENTATION WHATSOEVER.  AT CLOSING,
PURCHASER SHALL HAVE INSPECTED OR WAIVED ITS RIGHT TO INSPECT THE RECORDS AND
THE ASSETS FOR ALL PURPOSES AND SATISFIED ITSELF AS TO THE PHYSICAL AND
ENVIRONMENTAL CONDITION OF THE ASSETS, BOTH SURFACE AND SUBSURFACE, INCLUDING
BUT NOT LIMITED TO CONDITIONS SPECIFICALLY RELATED TO THE PRESENCE, RELEASE OR
DISPOSAL OF HAZARDOUS SUBSTANCES.  PURCHASER IS RELYING SOLELY UPON ITS OWN
INSPECTION OF THE ASSETS, AND, PURCHASER SHALL ACCEPT ALL OF THE SAME IN THEIR
"AS IS, WHERE IS" CONDITION.  IN ADDITION, SELLER MAKES NO WARRANTY OR
REPRESENTATION, EXPRESS, IMPLIED, STATUTORY OR OTHERWISE, AS TO THE ACCURACY OR
COMPLETENESS OF ANY DATA, REPORTS, RECORDS, PROJECTIONS, INFORMATION OR
MATERIALS NOW, HERETOFORE OR HEREAFTER FURNISHED OR MADE AVAILABLE TO PURCHASER
IN CONNECTION WITH THIS AGREEMENT, INCLUDING, WITHOUT LIMITATION, ANY
DESCRIPTION OF THE ASSETS, PRICING ASSUMPTIONS, OR QUALITY OR QUANTITY OF
HYDROCARBON RESERVES (IF ANY) ATTRIBUTABLE TO THE ASSETS OR THE ABILITY OR
POTENTIAL OF THE ASSETS TO PRODUCE HYDROCARBONS OR THE ENVIRONMENTAL CONDITION
OF THE ASSETS OR ANY OTHER MATTERS CONTAINED IN CONFIDENTIAL INFORMATION OR ANY
OTHER MATERIALS FURNISHED OR MADE AVAILABLE TO PURCHASER BY SELLER OR BY
SELLER'S AGENTS OR REPRESENTATIVES.  ANY AND ALL SUCH DATA, RECORDS, REPORTS,
PROJECTIONS, INFORMATION AND OTHER MATERIALS FURNISHED BY SELLER OR BY SELLER'S
AGENTS OR REPRESENTATIVES OR OTHERWISE MADE AVAILABLE TO PURCHASER ARE PROVIDED
TO PURCHASER AS A CONVENIENCE, AND SHALL NOT CREATE OR GIVE RISE TO ANY
LIABILITY OF OR AGAINST SELLER.  ANY RELIANCE ON OR USE OF THE SAME SHALL BE AT
PURCHASER'S SOLE RISK.  THE ASSIGNMENTS AND BILLS OF SALE OR OTHER CONVEYANCES
TO BE DELIVERED


                                          11
<PAGE>

BY SELLER AT CLOSING SHALL EXPRESSLY SET FORTH THE LIMITATIONS AND DISCLAIMERS
OF REPRESENTATIONS AND WARRANTIES CONTAINED IN THIS PARAGRAPH.

    Seller covenants and agrees that from and after the execution of this
Agreement and until the Closing Date:

    4.18 MAINTENANCE OF ASSETS.  Seller will not sell, transfer, assign, convey
or otherwise dispose of any of the Assets subject to Seller's direct control,
other than (a)  oil, gas and other hydrocarbons produced, saved and sold in the
ordinary course of business, (b) personal property and equipment which is
replaced with property and equipment of comparable or better value and utility
in the ordinary and routine maintenance and operation of the Subject Properties,
and (c) as required in connection with any exercise of preferential rights or as
otherwise required to satisfy obligations to third parties under contracts
presently existing.

    4.19 NO ENCUMBRANCES.  Seller will not create any lien, security interest
or encumbrance on the Sale Interest, the oil or gas attributable to the Assets,
or the proceeds thereof, other than Permitted Encumbrances.

    4.20 OPERATIONS.  With respect to any of the Subject Properties operated by
Seller or a third party, Seller will, subject to the rights of affected parties
under applicable agreements:

         (a)  cause the Subject Properties to be developed, maintained and
              operated in compliance with applicable laws, ordinances, rules,
              regulations and orders and in a prudent, good and workmanlike
              manner, maintain insurance now in force with respect to the
              Subject Properties, and pay or cause to be paid all costs and
              expenses in connection therewith;

         (b)  not participate in the drilling of any new well on the Subject
              Properties or fail to participate in operations on the Subject
              Properties proposed by other parties, without the advance written
              consent of Purchaser, which consent or non-consent must be given
              by Purchaser within three (3) days of the notice from Seller;

         (c)  not take any action or fail to take any action which is
              reasonably expected to result in any termination of the leases
              forming a part of the Subject Properties;

         (d)  perform and comply with all of its obligations under agreements
              relating to or affecting the Subject Properties;

         (e)  carry on its business with respect to the Subject Properties in
              substantially the same manner as it has heretofore, not
              introducing any new method of management, operation or accounting
              with respect to the Subject


                                          12

<PAGE>

Properties except as may be required by applicable statutes, rules or
regulations or by applicable presently existing contractual obligations;

         (f)  not enter into or assume any contract, agreement or commitment
              which is not in the ordinary course of business as heretofore
              conducted or which involves payments, receipts or potential
              liabilities with respect to the Subject Properties of more than
              $25,000, excluding emergency expenditures; and

         (g)  not resign or otherwise voluntarily relinquish its rights as
              operator of any Subject Property for which it serves as operator
              on the date hereof.

         (h)  not grant any preferential right to purchase or similar right or
              agree to require the consent of any party to the transfer and
              assignment of the Assets to Purchaser, subject to existing
              contractual obligations;

         (i)  not enter into any gas sales contract or crude oil sales or
              supply contract with respect to the Subject Properties which is
              not terminable without penalty upon notice of  thirty (30) days
              or less;

         (j)  not enter into any transaction the effect of which, considered as
              a whole, would be to cause Seller's ownership interest in any of
              the Subject Properties to be altered from its ownership interest
              as of the date hereof;

         (k)  not enter into any settlement of or relinquish any outstanding
              receivables which are a part of the Assets (including, without
              limitations, the right to receive any retroactive price
              adjustments, take-or-pay monies, FERC mandated refunds,
              accounting adjustments, tax adjustments, and Minerals Management
              Service refunds);

         (l)  if any approval or consent by any federal, state or local
              governmental authority is required to vest Acceptable Title to
              any of the Sale Interest in Purchaser at Closing, exercise its
              best efforts, as reasonably requested in writing by Purchaser, to
              obtain all such required approvals or consents at Purchaser's
              expense;

         (m)  through Closing, give prompt written notice to Purchaser of any
              notice of default (or written threat of default, whether disputed
              or denied) received or given by Seller under any instrument or
              agreement affecting the Subject Properties to which Seller is a
              party or by which it or any of the Subject Properties is bound;
              and

         (n)  to the extent it can do so without violating any third party
              agreement and subject to the rights of third parties, exercise
              its best efforts to provide (as


                                          13

<PAGE>

              soon as practicable) Purchaser with a copy of each authority for
              expenditure and contract affecting the Subject Properties entered
              into after the date hereof; PROVIDED, however, that the provision
              of such matters to Purchaser is for informational purposes only
              and that Purchaser shall have no right to comment upon or object
              to any such matter that is otherwise not in violation of this
              Agreement.


          ARTICLE 5.  REPRESENTATIONS, WARRANTIES AND COVENANTS OF PURCHASER

    Purchaser represents and warrants to and covenants with Seller that
(PROVIDED, that each of CPC and CELLC, respectively, makes such representations,
warranties and covenants solely with respect to itself and not as to the other):

    5.1  EXISTENCE.  CELLC is a limited liability company duly organized,
validly existing and in good standing under the laws of the State of Texas.  CPC
is a corporation duly organized, validly existing and in good standing under the
laws of the State of Texas.

    5.2  POWER.  Purchaser has the requisite power and authority to enter into
and perform this Agreement and the transactions contemplated hereby.  The
execution, delivery and performance of this Agreement by Purchaser, and the
transactions contemplated hereby, will not (a) violate any provision of any
Purchaser's certificate or articles of incorporation or organization, as the
case may be, bylaws, regulations or other governing documents; (b) to the best
knowledge and belief of Purchaser, conflict with, result in a breach of,
constitute a default (or an event that with the lapse of time or notice, or both
would constitute a default) under any agreement or instrument to which Purchaser
is a party or by which Purchaser is bound, (c) to the best knowledge and belief
of Purchaser, violate any judgment, order, ruling, or decree applicable to
Purchaser and entered or delivered in a proceeding in which Purchaser was or is
a named party; or (d) to the best knowledge and belief of Purchaser, violate any
applicable law, rule or regulation.

    5.3  AUTHORIZATION.  The execution, delivery and performance of this
Agreement and the transactions contemplated hereby have been duly and validly
authorized by all requisite action on the part of Purchaser.  This Agreement has
been duly executed and delivered on behalf of Purchaser, and at the Closing all
documents and instruments required hereunder to be executed and delivered by
Purchaser shall have been duly executed and delivered.  This Agreement and such
documents and  instruments shall constitute legal, valid and binding obligations
of Purchaser enforceable in accordance with their terms, subject, however, to
the effect of bankruptcy, insolvency, reorganization, moratorium and similar
laws from time to time in effect relating to the rights and remedies of
creditors, as well as to general  principles of equity (regardless of whether
such enforceability is considered in a proceeding in equity or at law).


                                          14

<PAGE>

    5.4  BROKERS.  Purchaser has not incurred any obligation or liability,
contingent or otherwise, for brokers' or finders' fees in respect of the matters
provided for in this Agreement which will be the responsibility of Seller, and
any such obligation or liability that might exist shall be the sole obligation
of Purchaser.

    5.5  INVESTMENT INTENT.  Purchaser is acquiring the Assets for Purchaser's
own account for investment, and not with a view to, or for resale in connection
with, any distribution thereof within the meaning of the Securities Act of 1933,
and shall not resell any or all of the Assets except in compliance with all
applicable securities laws.

    5.6  ADDITIONAL INTERESTS.  If offered in writing to Purchaser by PPDLP,
Purchaser shall have the option to purchase, upon essentially the same terms and
conditions as contained herein, all additional right, title and interest, if
any, in and to the Assets acquired after the Effective Time by PPDLP, and, if
such option is exercised, the consideration paid therefor shall be the purchase
price paid by PPDLP.  Notwithstanding the immediately preceding sentence,
Purchaser shall purchase at Closing all interests in any of the Assets (which
are purchased by Purchaser) and described on Appendix I attached hereto offered
by the Persons identified on Appendix I for the purchase price described on
Appendix I (which amount has been included in the Purchase Price), whether or
not such interests are acquired by PPDLP prior to Closing, unless such interests
are subject to Defects specifically included in any Notice of Defects delivered
hereunder, in which case, at PPDLP's sole option, (i) such affected interest
shall be excluded from the Assets and the Purchase Price shall be reduced by the
Purchase Price allocated thereto on Appendix I, or (ii) the Purchase Price shall
be reduced by the purchase price allocated thereto on Appendix I and such
interest shall be conveyed to Purchaser at Closing as a part of the Assets. All
such interests acquired by Purchaser shall be deemed to be a part of the Sale
Interest for all purposes.


                      ARTICLE 6.  SELLER'S CONDITIONS OF CLOSING

    Seller's obligation to consummate the transactions provided for herein is
subject only to the satisfaction or waiver by Seller on or before the Closing
Date of the following conditions:

    6.1  REPRESENTATIONS.  The representations and warranties of Purchaser
contained in Article 5 shall be true and correct in all material respects on the
Closing Date as though made on and as of that date.

    6.2  PERFORMANCE.  Purchaser shall have performed in all material respects
the obligations, covenants and agreements hereunder to be performed by it at or
prior to the Closing.


                                          15
<PAGE>

    6.3  OFFICER'S CERTIFICATE.  Each Purchaser shall have delivered to Seller
a certificate of an executive officer dated the Closing Date, certifying on
behalf of such Purchaser that the conditions set forth in Sections 6.1 and 6.2
have been fulfilled.

    6.4  PENDING MATTERS.  No suit, action or other proceeding by a third party
or a governmental authority shall be pending or threatened which seeks
substantial damages from Seller in connection with, or seeks to restrain, enjoin
or otherwise prohibit, the consummation of the transactions contemplated by this
Agreement.

    6.5  HSR ACT.  The waiting period required by the HSR Act (as defined in
Section 13.20 below) shall have expired or been terminated.


                    ARTICLE 7.  PURCHASER'S CONDITIONS OF CLOSING

    Purchaser's obligation to consummate the transactions provided for herein
is subject only to the satisfaction or waiver by Purchaser on or before the
Closing Date of the following conditions:

    7.1  REPRESENTATIONS.  The representations and warranties of Seller
contained in Article 4 shall be true and correct in all material respects on the
Closing Date as though made on and as of that date.

    7.2  PERFORMANCE.  Seller shall have performed in all material respects the
obligations, covenants and agreements hereunder to be performed by it at or
prior to the Closing.

    7.3  OFFICER'S CERTIFICATE.  Seller shall have delivered to Purchaser
certificates of  executive officers of Seller's respective general partners,
dated the Closing Date, certifying on behalf of such Seller that the conditions
set forth in Sections 7.1 and  7.2 have been fulfilled.

    7.4  PENDING MATTERS.  No suit, action or other proceeding by a third party
or a governmental authority shall be pending or threatened which seeks
substantial damages from Purchaser in connection with or, seeks to restrain,
enjoin or otherwise prohibit, the consummation of the transactions contemplated
by this Agreement.

    7.5  HSR ACT.  The waiting period required by the HSR Act (as defined in
Section 13.20 below) shall have expired or been terminated.


                                 ARTICLE 8.  CLOSING

    8.1  TIME AND PLACE OF CLOSING.  If the conditions to Closing have been
satisfied or expressly waived by the party entitled to the benefits thereof, the
consummation of the transactions contemplated hereby ("CLOSING") shall take
place at Seller's offices in Midland,


                                          16

<PAGE>

Texas, on June 12, 1995, at 9:00 a.m, or at  such other place and time or in
such other manner agreed upon by Seller and Purchaser ("CLOSING DATE");
PROVIDED, that Seller shall have the right to extend Closing for up to thirty
(30) days to respond to any Notice of Defects provided by Purchaser and that any
extension by Seller shall not serve to provide Purchaser rights not otherwise
expressly provided herein, nor to extend any rights of Purchaser contained
herein, including, without limitation, those contained in Section 3.5.

    8.2  CLOSING OBLIGATIONS.  At the Closing,

    (a)  Seller shall execute, acknowledge and deliver to Purchaser an
         Assignment  and Bill of Sale in substantially the form attached hereto
         as Exhibit "B", conveying the Assets to Purchaser as provided hereby;

    (b)  Seller and Purchaser shall execute, acknowledge and deliver transfer
         orders or letters in lieu thereof directing all purchasers of
         production to make payment to Purchaser of proceeds attributable to
         the Sale Interest;

    (c)  Purchaser shall deliver the Adjusted Purchase Price as provided in
         Article 2;

    (d)  Purchaser and Seller shall execute and deliver a settlement statement
         (the "PRELIMINARY SETTLEMENT STATEMENT") prepared by Seller and
         setting forth the Purchase Price and all adjustments thereto agreed
         upon by the parties, using the best information available, subject to
         Section 13.18; and

    (e)  Purchaser and Seller shall execute such other instruments and take
         such other action as may be necessary to carry out their respective
         obligations under this Agreement.


                         ARTICLE 9.  POST-CLOSING OBLIGATIONS

    9.1  RECEIPTS AND CREDITS; SUSPENSE FUNDS.  Subject to the terms hereof,
all monies, refunds, proceeds, receipts, credits and income attributable to the
purchased Assets (a) for all periods of time from and after the Effective Time
shall be the sole property and entitlement of the Purchaser, and, to the extent
received by Seller, Seller shall fully disclose and account therefor to
Purchaser promptly, and (b) for all periods of time prior to the Effective Time
shall be the sole property and entitlement of Seller to the extent received by
Purchaser or Seller prior to the Final Accounting Date or allocated to Seller in
the Final Accounting, and if received by Purchaser, Purchaser shall fully
disclose and account therefore to Seller promptly. Purchaser shall pay Seller
for Seller's share of hydrocarbons attributable to the purchased Assets in
storage above the pipeline connection or in transit on the Effective Time at the
purchaser's then posted field price for hydrocarbons of like grade and gravity
in the relevant field, net of all applicable taxes.  Seller and Purchaser
recognize that as of the Effective Time there may be over or under imbalances
with respect to gas production, gathering, transportation or processing
attributable


                                          17

<PAGE>

to the Subject Properties ("IMBALANCES") and hereby agree that (i) Imbalances
shall not be included in any Identified Claims asserted hereunder, and (ii) the
Subject Properties will be conveyed specifically subject to Imbalances which
exist as of the Effective Time, with Purchaser, as of Closing, bearing and
assuming all obligations with respect to any overproduction account or liability
and receiving the benefit of and being credited with any underproduction account
or credit.  At Closing, Seller shall deliver to Purchaser all amounts in
Seller's possession due third party owners of interests in the Subject
Properties, and Purchaser agrees that it shall be solely responsible for the
disposition of such funds, the payment thereof to the rightful owners and the
payment, if any, of royalty thereon (the "SUSPENSE FUNDS").

    9.2  COSTS AND LIABILITIES; INDEMNITY.

         (a)  As used in this Agreement, "CLAIMS" shall include costs,
              expenses, obligations, claims, demands, causes of action,
              liabilities, damages, fines, penalties and judgments of any kind
              or character, whether matured or unmatured, absolute or
              contingent, accrued or unaccrued, liquidated or unliquidated,
              known or unknown, and all costs and fees (including, without
              limitation, interest, attorneys' fees, costs of experts, court
              costs and costs of investigation) incurred in connection
              therewith, including, but not limited to claims arising from or
              directly or indirectly related to royalty, operating, suspense
              and capital obligations attributable to the purchased Assets.  As
              used in this Section 9.2, "ASSETS" shall include the Suspense
              Funds.

         (b)  Notwithstanding anything in this Agreement to the contrary, it is
              the express intent and agreement of Seller and Purchaser that, if
              Closing occurs, Purchaser shall accept the purchased Assets in
              their "AS IS, WHERE IS" condition, subject to any and all
              defects, deficiencies, irregularities and claims related or
              attributable in any manner  thereto, including, without
              limitation, Title Defects, Contract Defects, Environmental
              Defects, Identified Claims or any other matter affecting in any
              respect the title or physical condition of,  or the right to own,
              use, operate, develop or enjoy, the purchased Assets, whether
              known or unknown, liquidated or unliquidated, fixed or
              contingent, direct or indirect.

         (c)  At Closing and without further action or documentation, Purchaser
              (i) shall assume, be responsible for and comply with all duties
              and obligations, express or implied, arising at any time with
              respect to the purchased Assets, including, without limitation
              (1) those arising under or by virtue of any lease, contract,
              agreement, document, permit, law, statute, rule, regulation or
              order of any governmental authority or court (specifically
              including, without limitation, any governmental request or other
              requirement to plug, re-plug or abandon any well of whatsoever
              type, status or classification, or take any clean-up, remedial or
              other


                                          18

<PAGE>

              action with respect to the purchased Assets), (2) preferential
              rights to purchase and (3) third party consents; (ii) shall
              assume, be responsible for and pay all claims affecting or
              arising, directly or indirectly, at any time in connection with
              the purchased Assets, including, without limitation, claims for
              personal or property injury or damage, environmental cleanup,
              remediation, or compliance, or for any other relief, arising
              directly or indirectly from or incident to, the use, occupation,
              operation, maintenance or abandonment of or production from the
              purchased Assets, or condition of the purchased Assets, whether
              latent or patent, including, without limitation, contamination of
              property or premises with Naturally Occurring Radioactive
              Materials ("NORM"), and whether or not arising solely from or
              contributed to by the negligence in any form, whether active or
              passive, or of any kind or nature, of Seller or its predecessors
              in title or their respective agents, employees or contractors;
              and (iii) shall defend, indemnify and hold Seller harmless from
              any and all claims arising, asserted or due at any time in
              connection with the foregoing.

         (d)  From and after Closing, any claim for indemnity hereunder shall
              be made by written notice, together with a written description of
              any claims asserted stating the nature and basis of such claim
              and, if ascertainable, the amount thereof.  Purchaser shall have
              a period of twenty (20) days after receipt of such notice within
              which to respond thereto or, in the case of a claim which
              requires a shorter time for response, then within such shorter
              period as specified by Seller in such notice (the "NOTICE
              PERIOD").  If Purchaser denies liability hereunder or fails to
              provide the defense for any claim, Seller may defend or
              compromise the claim as it deems appropriate without prejudice to
              any of Seller's rights hereunder, with no right of Purchaser to
              approve or disapprove any actions taken in connection therewith
              by Seller.  If Purchaser accepts liability and responsibility for
              the defense of any claim, it shall so notify Seller as soon as is
              practicable prior to the expiration of the Notice Period and
              undertake the defense or compromise of such claim with counsel
              selected by Purchaser and reasonably acceptable to Seller.  If
              Purchaser undertakes the defense or compromise of such claim,
              Seller shall be entitled, at its own expense, to participate in
              such defense.  No compromise or settlement of any claim shall be
              made without reasonable notice to Seller, and without the prior
              written approval of Seller, which approval shall not be
              unreasonably withheld or delayed, unless such compromise or
              settlement includes a general and complete release of Seller, its
              Affiliates and their respective Representatives in respect of the
              matter, with prejudice, and with no express or written admission
              of liability on the part of Seller, its Affiliates and their
              respective Representatives, and no constraints on the future
              conduct of its or their respective businesses.


                                          19

<PAGE>

         (e)  Seller shall have the right at all times to participate, at its
              sole cost, in the preparation for any hearing or trial related to
              the indemnities set forth in this Agreement, as well as the right
              to appear on its own behalf or to retain separate counsel to
              represent it at any such hearing or trial.

         (f)  THE INDEMNITIES PROVIDED IN THIS AGREEMENT SHALL EXTEND TO SELLER
              AND ITS AFFILIATES AND ANY PERSON WHO AT ANY TIME HAS SERVED OR
              IS SERVING AS A DIRECTOR, OFFICER, EMPLOYEE, CONSULTANT, INVITEE
              OR AGENT THEREOF (EACH A "REPRESENTATIVE"), AND EACH OF THEIR
              RESPECTIVE HEIRS, EXECUTORS, SUCCESSORS AND ASSIGNS, AND SHALL
              APPLY TO ALL CLAIMS SUBJECT TO INDEMNITY HEREUNDER, INCLUDING
              THOSE BASED ON NEGLIGENCE OF ANY NATURE, INCLUDING SOLE
              NEGLIGENCE, SIMPLE NEGLIGENCE, CONCURRENT NEGLIGENCE, ACTIVE
              NEGLIGENCE, PASSIVE NEGLIGENCE, STRICT LIABILITY OR FAULT OF
              SELLER (OR ANY OTHER INDEMNIFIED PARTY) OR ANY OTHER THEORY OF
              LIABILITY OR FAULT, WHETHER OF LAW (WHETHER COMMON OR STATUTORY)
              OR IN EQUITY; PROVIDED, HOWEVER, PURCHASER SHALL NOT BE LIABLE
              FOR OR INDEMNIFY SELLER FOR ANY CLAIM ASSERTED BY PURCHASER AND
              ARISING FROM A BREACH BY SELLER OF THIS AGREEMENT.  THE
              INDEMNIFICATION PROVISIONS OF THIS SECTION 9.2 SHALL BE IN
              ADDITION TO ANY OTHER INDEMNITY PROVISIONS CONTAINED IN THIS
              AGREEMENT, AND IT IS EXPRESSLY UNDERSTOOD AND AGREED THAT THE
              TERMS OF THIS SECTION 9.2 SHALL CONTROL OVER ANY CONFLICTING OR
              CONTRADICTING TERMS OR PROVISIONS CONTAINED IN THIS AGREEMENT,
              AND SHALL SURVIVE CLOSING.

    9.3  FURTHER ASSURANCES.  After Closing, Seller and Purchaser agree to take
such further actions and to execute, acknowledge and deliver all such further
documents that are necessary or useful in carrying out the purposes of this
Agreement or of any document delivered pursuant hereto.

    9.4  DELIVERY OF RECORDS.  As soon as reasonably possible but no later than
thirty (30) days after the Closing Date, Seller shall deliver originals (or
copies where originals are not available) of the Records to Purchaser; PROVIDED,
that Seller (i) shall exercise its best efforts to provide Purchaser at Closing
or as soon thereafter as is practicable with all Records necessary to assume and
conduct operations of the Assets, and (ii) shall have the right to retain, as
its own, original Records that pertain to the Excluded Assets and copies of all
other Records.


                                          20

<PAGE>


    9.5  ACCOUNTING FOR SUBJECT PROPERTIES.  At the request of Purchaser,
Seller shall continue to account for all Subject Properties presently operated
by it through the last day of the month in which Closing occurs, in accordance
with its customary procedures; PROVIDED, however, that such accounting shall be
for Purchaser's sole benefit and at Purchaser's sole risk and that Purchaser
shall indemnify Seller for such activities in accordance with Section 9.2.

    9.6  ACCESS TO DATA.  Subject to the rights of third parties and to the
extent attributable to the purchased Subject Properties, Seller shall provide
Purchaser reasonable access at their place of storage to all seismic, geologic
and geophysical records and data not obtained from SFER, SFEOP, SFERP-A or any
of their respective Affiliates and in Seller's possession as of the Effective
Time.  Subject to the rights of third parties and Seller's proprietary rights,
Seller shall provide Purchaser with reasonable access to Seller's books and
records after Closing as necessary for Purchaser to prepare its financial
statements.


                               ARTICLE 10.  TERMINATION

    10.1 RIGHT OF TERMINATION.  This Agreement and the transactions
contemplated hereby may be terminated at any time at or prior to the Closing:

         (a)  By Seller if Closing does not occur on or before July 12, 1995;

         (b)  By mutual consent of the parties;

         (c)  By Purchaser or Seller in accordance with Section 3.6;

         (d)  By Purchaser by notice delivered to Seller on or before Closing
              if all conditions described in Article 7 shall not have been met
              and such noncompliance shall not have been caused or waived by
              the actions or inactions of Purchaser; or

         (e)  By Seller by notice delivered to Purchaser on or before Closing
              if (i) all conditions described in Article 6 shall not have been
              met and such noncompliance shall not have been caused or waived
              by the actions or inactions of Seller, or (ii) Purchaser has not
              made the filings and requests required of it by the first
              sentence of Section 13.20 prior to April 17, 1995.

    10.2 EFFECT OF TERMINATION.  If this Agreement is terminated pursuant to
Section 10.1, this Agreement shall become void and of no further force or effect
(except for the provisions of Sections 4.4, 5.4,  13.1 through 13.11 and 13.14
through 13.17, each of which shall survive such termination and continue in full
force and effect); PROVIDED, however, (i) that if either party is in material
default of its obligations under this Agreement at the time this Agreement is so
terminated, such defaulting party shall continue to be liable to the other party
for damages and


                                          21

<PAGE>

other remedies available at law or in equity (including, without limitation, for
specific performance) in respect of such default and such liability shall not be
affected by such termination; and (ii) if this Agreement is so terminated by
Purchaser, in the absence of a default hereunder by Purchaser, the Deposit shall
be returned to Purchaser, or if so terminated by Seller, as the result of a
default hereunder by Purchaser, the Seller may, in its sole discretion, elect to
retain the Deposit as liquidated damages (it being agreed by the parties that
damages in said event would be extremely difficult to determine, and that the
Deposit represents a fair and reasonable estimate of such damages under the
circumstances, and does not constitute a penalty).  Notwithstanding anything to
the contrary contained in this Agreement, upon any termination of this Agreement
pursuant to Section 10.1 by Seller, in the absence of a material default
hereunder by Seller, Seller shall be free immediately to enjoy all rights of
ownership of the Assets and may sell, transfer, encumber or otherwise dispose of
the Assets to any party without any restriction under this Agreement and without
any impairment of its rights hereunder to recover damages from Purchaser arising
from any default hereunder by Purchaser; PROVIDED, that Seller's right to seek
specific performance of Purchaser's obligations hereunder shall be waived upon
any such disposition of the Assets and that its right to seek or recover any
other damages shall be waived upon its election to retain the Deposit.


                                  ARTICLE 11.  TAXES

    11.1      APPORTIONMENT OF AD VALOREM AND PROPERTY TAXES.  All ad valorem
taxes, real property taxes, personal property taxes, and similar obligations
concerning the Assets with respect to the tax period in which the Effective Time
occurs ("PROPERTY TAXES") shall be apportioned as of the Effective Time between
Seller and Purchaser.  Seller shall file or cause to be filed all required
reports and returns incident to the Property Taxes and shall pay or cause to be
paid to the taxing authorities all Property Taxes relating to the tax period in
which the Effective Time occurs.  Purchaser shall pay to Seller Purchaser's pro
rata portion of Property Taxes within thirty (30) days after receipt of Seller's
invoice therefor.

    11.2      SALES TAXES.  The Purchase Price excludes any sales taxes or
other taxes required to be paid in connection with the sale of property pursuant
to this Agreement.  Purchaser shall be liable for all sales, use and other
taxes, conveyance, transfer and recording fees and real estate transfer stamps
or taxes that may be imposed on any transfer of property pursuant to this
Agreement.  These taxes shall be collected and remitted under applicable law.
Purchaser shall indemnify and hold Seller harmless with respect to the payment
of any of these taxes including any interest or penalties assessed thereon.

    11.3      OTHER TAXES.  All taxes (other than income taxes) which are 
imposed on or with respect to the production of oil, natural gas or other 
hydrocarbons or minerals or the receipt of proceeds therefrom (including but 
not limited to severance, production, and excise taxes) shall be apportioned 
between the parties based upon  the respective shares of production taken by 
the parties. From and after Closing, Purchaser shall be responsible for 
paying or withholding or

                                          22

<PAGE>

causing to be paid or withheld all such taxes and for filing all statements,
returns, and documents incident thereto.

    11.4      COOPERATION.  Each party to this Agreement shall provide the
other party with reasonable access to all relevant documents, data and other
information which may be required by the other party for the purpose of
preparing tax returns and responding to any audit by any taxing jurisdiction.
Each party to this Agreement shall cooperate with all reasonable requests of the
other party made in connection with contesting the imposition of taxes.
Notwithstanding anything to the contrary in this Agreement, neither party to
this Agreement shall be required at any time to disclose to the other party any
tax return or other confidential tax information.


                     ARTICLE 12.  PHYSICAL CONDITION OF THE ASSETS

    12.1      PRIOR USE OF ASSETS.  THE ASSETS HAVE BEEN USED FOR OIL AND GAS
DRILLING AND PRODUCING OPERATIONS AND RELATED OIL FIELD OPERATIONS.  PHYSICAL
CHANGES IN THE LAND MAY HAVE OCCURRED AS A RESULT OF SUCH USES.  THE ASSETS ALSO
MAY INCLUDE BURIED PIPELINES AND OTHER EQUIPMENT,  WHETHER OR NOT OF A SIMILAR
NATURE, THE LOCATIONS OF WHICH MAY NOT NOW BE KNOWN BY SELLER OR READILY
APPARENT BY A PHYSICAL INSPECTION OF THE PROPERTY.  PURCHASER UNDERSTANDS THAT
SELLER DOES NOT HAVE THE REQUISITE INFORMATION WITH WHICH TO DETERMINE THE EXACT
NATURE OR CONDITION OF THE ASSETS OR THE AFFECT ANY SUCH USE HAS HAD ON THE
PHYSICAL CONDITION OF THE LANDS BURDENED BY THE ASSETS.

    12.2      ASSUMPTION OF ASSETS IN PRESENT CONDITION.  PURCHASER
ACKNOWLEDGES THAT (i) THE CONSUMMATION OF THIS AGREEMENT BY PURCHASER SHALL BE
ON THE BASIS OF ITS OWN INVESTIGATION OF THE PHYSICAL CONDITION OF THE ASSETS,
INCLUDING, WITHOUT LIMITATIONS, SUBSURFACE CONDITION; (ii) THE ASSETS HAVE BEEN
USED IN THE MANNER AND FOR THE PURPOSES SET FORTH ABOVE AND THAT PHYSICAL
CHANGES TO THE ASSETS AND THE LANDS BURDENED THEREBY MAY HAVE OCCURRED AS A
RESULT OF SUCH USE; AND (iii) NORM AND MAN-MADE MATERIAL FIBERS ("MMMF") MAY BE
PRESENT AT SOME LOCATIONS.  PURCHASER ACKNOWLEDGES THAT NORM IS A NATURAL
PHENOMENON ASSOCIATED WITH MANY OIL FIELDS IN THE UNITED STATES AND THROUGHOUT
THE WORLD. PURCHASER SHALL MAKE ITS OWN DETERMINATION OF THIS PHENOMENON AND
OTHER CONDITIONS.  SELLER DISCLAIMS ANY LIABILITY ARISING OUT OF OR IN
CONNECTION WITH ANY PRESENCE OF NORM OR MMMF ON OR AFFECTING THE ASSETS.  IN
ACCORDANCE WITH SECTION 9.2 AND AT CLOSING, PURCHASER SHALL ASSUME THE RISK THAT
THE PURCHASED ASSETS MAY CONTAIN WASTES OR CONTAMINANTS AND ADVERSE PHYSICAL
CONDITIONS, INCLUDING THE PRESENCE OF PIPELINES, EQUIPMENT AND OTHER ITEMS OF
PERSONAL PROPERTY, AND WASTES OR CONTAMINANTS WHICH MAY

                                          23

<PAGE>

NOT HAVE BEEN REVEALED BY PURCHASER'S INVESTIGATION.  IN ACCORDANCE WITH SECTION
9.2 AND AT CLOSING, ALL RESPONSIBILITY AND LIABILITY RELATED TO DISPOSALS,
SPILLS, WASTES, OR CONTAMINATION, OR OTHER ADVERSE PHYSICAL CONDITIONS ON,
BELOW, OR RELATED TO OR AFFECTING THE PURCHASED ASSETS SHALL BE ASSUMED BY
PURCHASER AND PURCHASER SHALL, NOTWITHSTANDING WHEN THE BASIS FOR ANY CLAIM,
ACTION, SUIT, JUDGMENT (INCLUDING, WITHOUT LIMITATION, THOSE FOR DEATH, PERSONAL
INJURY OR PROPERTY DAMAGE) SHALL HAVE OCCURRED, INDEMNIFY, DEFEND AND HOLD
SELLER HARMLESS THEREFROM PURSUANT TO SECTION 9.2.

    12.3      CASUALTY LOSS.  In the event of any material damage by fire or
other casualty to any of the Assets prior to the Closing ("CASUALTY LOSS"), this
Agreement shall remain in full force and effect, and as to each affected Asset,
Seller shall at its election either collect (and when collected pay over to
Purchaser) or assign to Purchaser any and all insurance claims related to such
damage, and Purchaser shall take title to the affected Asset without reduction
in the Purchase Price.


                             ARTICLE  13.  MISCELLANEOUS

    13.1       GOVERNING LAW.  This Agreement and all instruments executed in
accordance herewith shall be governed by and interpreted in accordance with the
laws of the State of Texas, without regard to conflict of law rules that would
direct  application of the laws of another jurisdiction, except to the extent
that it is mandatory that the law of the jurisdiction wherein the Assets are
located shall apply.  In the event of any litigation or other proceeding in
connection with this Agreement, the venue for any such proceeding shall be in a
court of competent jurisdiction located in Midland County, Texas, and the
prevailing party shall be entitled to recover its reasonable attorney's fees and
costs incurred therein from the other party, in addition to any damages awarded.

    13.2      ENTIRE AGREEMENT.  This Agreement, the letter agreement of even
date between the parties, the Assignment and Bill of Sale and the
Confidentiality Agreement dated February 17, 1995, as amended, between CPC,
CELLC and Parker & Parsley Petroleum Company (the "CONFIDENTIALITY AGREEMENT")
constitute the entire agreement between the parties and supersede all prior
agreements, understandings,  negotiations and discussions, whether oral or
written, of the parties.  No supplement, amendment, alteration, modification,
waiver or termination of this Agreement shall be binding unless executed in
writing by the parties hereto.

    13.3       WAIVER.  No waiver of any of the provisions of this Agreement
shall be deemed or shall constitute a waiver of any other provisions hereof
(whether or not similar), nor shall such waiver constitute a continuing waiver
unless otherwise expressly provided.


                                          24

<PAGE>

    13.4       CAPTIONS.  The captions in this Agreement are for convenience
only and shall not be considered a part of or affect the construction or
interpretation of any provision of this Agreement.

    13.5      ASSIGNABILITY.  Except pursuant to a like kind exchange pursuant
to Section 2.3, neither party hereto shall assign (whether before, at or after
Closing) this Agreement or any of its rights or obligations hereunder without
the prior written consent of the other party, which may be withheld for any or
no reason.  Any assignment made without such consent shall be void.  Except as
otherwise provided herein, this Agreement shall be binding upon and inure to the
benefit of the parties hereto and their respective permitted successors and
assigns; PROVIDED, that Seller agrees (i) that Purchaser may submit its written
request received on or before June 2, 1995, that Seller consent to the
conveyance at Closing of certain of the Assets to Valley Gathering Company, a
Texas corporation and an Affiliate of Purchaser, and (ii) that Seller shall not
unreasonably withhold its consent to such request; PROVIDED, that for the
purposes of this Agreement, expressly including, without limitation, Article 9,
all such Assets conveyed to Valley Gathering Company shall be deemed to be
Assets purchased hereunder by Purchaser.

    13.6       NOTICES.  Any notice provided or permitted to be given under
this Agreement shall be in writing, and may be served by personal delivery or by
registered or certified U.S. mail, addressed to the party to be notified,
postage prepaid, return receipt requested.  Notice deposited in the mail in the
manner hereinabove described shall be deemed to have been given and received on
the date of the delivery as shown on the return receipt.  Notice served in any
other manner (including by facsimile delivery) shall be deemed to have been
given and received only if and when actually received by the addressee.  For
purposes of notice, the addresses of the parties shall be as follows:

SELLER:

    Parker & Parsley Development L.P.
    Parker & Parsley Producing L.P.
    Attn:  Tim Leach and W.T. Howard
    303 W. Wall, Suite 101
    Midland, Texas  79701
    Telephone:     (915) 683-4768
    Fax:           (915) 571-5208

    with copy to:  David W. Copeland
                   303 W. Wall, Suite 101
                   Midland, Texas  79701
                   Telephone:  (915) 683-4768
                   Fax:        (915) 571-5815


                                          25

<PAGE>

PURCHASER:

    Costilla Energy, L.L.C.
    Attn: Cliff Hair
    511 West Texas
    Midland, Texas  79701
    Telephone:     (915) 683-3092
    Fax:           (915) 685-0841

    with copy to:  Michael J. Grella
                   511 West Texas
                   Midland, Texas  79701
                   Telephone:     (915) 683-3092
                   Fax:           (915) 685-0841

Each party shall have the right, upon giving three (3) days prior notice to the
other in the manner hereinabove provided, to change its address for purposes of
notice to any other appropriate street address.

    13.7       DTPA WAIVER.  TO THE EXTENT APPLICABLE TO THE ASSETS OR ANY
PORTION THEREOF, EACH PURCHASER HEREBY WAIVES THE PROVISIONS OF THE TEXAS
DECEPTIVE TRADE PRACTICES ACT, CHAPTER 17, SUBCHAPTER E, SECTIONS 17.41 THROUGH
17.63, INCLUSIVE (OTHER THAN SECTION 17.555, WHICH IS NOT WAIVED), TEX. BUS. &
COM. CODE.  IN ORDER TO  EVIDENCE ITS ABILITY TO GRANT SUCH WAIVER, PURCHASER
HEREBY REPRESENTS AND WARRANTS TO SELLER THAT IT (i) IS IN THE BUSINESS OF
SEEKING OR ACQUIRING, BY PURCHASE OR LEASE, GOODS OR SERVICES FOR COMMERCIAL OR
BUSINESS USE; (ii) HAS ASSETS OF $5,000,000 OR MORE ACCORDING TO ITS MOST RECENT
FINANCIAL STATEMENT PREPARED IN ACCORDANCE WITH GENERALLY ACCEPTED ACCOUNTING
PRINCIPLES; (iii) HAS KNOWLEDGE AND EXPERIENCE IN FINANCIAL, BUSINESS AND OIL
AND GAS MATTERS THAT ENABLE IT TO EVALUATE THE MERITS AND RISKS OF THE
TRANSACTIONS CONTEMPLATED HEREBY; (iv) IS NOT IN A SIGNIFICANTLY DISPARATE
BARGAINING POSITION; AND (v) THAT THIS WAIVER IS A MATERIAL AND INTEGRAL PART OF
THIS AGREEMENT AND THE CONSIDERATION THEREOF.

    13.8      EXPENSES.  Each party shall be solely responsible for all
expenses incurred by it in connection with this transaction (including, without
limitation, fees and expenses of its own legal counsel and accountants).

    13.9       SEVERABILITY.  If any term or other provision of this Agreement
is invalid, illegal or incapable of being enforced under any rule of law, all
other conditions and provisions of this Agreement shall nevertheless remain in
full force and effect so long as the economic or legal

                                          26

<PAGE>

substance of the transactions contemplated hereby is not affected in a
materially adverse manner with respect to either party.

    13.10     DAMAGES.   The parties waive any rights to punitive and
incidental or consequential damages resulting from a breach of this Agreement.

    13.11     NO THIRD PARTY BENEFICIARY.  This Agreement is not intended to
create, nor shall it be construed to create, any rights in any third party under
doctrines concerning third party beneficiaries.

    13.12     SURVIVAL.  The representations and warranties of the parties
under this Agreement shall not survive, but shall terminate upon and be
extinguished by, Closing; PROVIDED, however, that (i) all representations,
waivers, covenants, agreements and indemnities contained entirely within
Sections 1.2, 3.1, 3.6, 4.1 through 4.5 and 5.1 through 5.6, and Articles 9, 11,
12 or 13 of this Agreement shall survive the Closing, and (ii) Seller's
obligation with respect to Further Conveyances (as defined in Section 3.1 above)
shall expire on the first anniversary of the Closing Date with respect to
matters not asserted prior to such anniversary date with the specificity
required of Notice of Defects given hereunder; FURTHER PROVIDED, that,
notwithstanding anything herein to the contrary, Purchaser expressly agrees and
acknowledges that it shall have no remedy or recourse against Seller or its
Affiliates or any of their respective Representatives with respect to the
condition of the Assets or any representation or warranty made in connection
with this Agreement, except as expressly provided by Section 3.6.

    13.13     COUNTERPARTS.  This Agreement may be executed in one or more
counterparts, each of which shall be deemed an original, but all of which
together shall constitute one and the same instrument.

    13.14     CERTAIN DEFINITIONS.  As used in this Agreement, (a) the term
"AFFILIATE" means, as to any Person, each other Person that directly or
indirectly (through one or more intermediaries or otherwise) controls, is
controlled by, or is under common control with, such Person; (b) the term
"PERSON" means an individual, corporation, partnership, association, joint stock
company, trust or trustee thereof, estate or executor thereof, unincorporated
organization or joint venture, court or other governmental unit or any agency or
subdivision thereof, or any other legally recognizable entity; and (c) the terms
"TO [SELLER'S OR PURCHASER'S, AS THE CASE MAY BE] KNOWLEDGE"  or "KNOWN TO"  and
other terms of similar import shall mean, with respect to the referenced party,
only the then existing actual non-privileged knowledge of any president or vice
president of such party or of such party's general or managing partner or agent,
as the case may be, and are not intended to imply that such party in fact has
actual knowledge of the subject matter to which such terms apply.

    13.15     CONSTRUCTION OF AMBIGUITY.  In the event of any ambiguity in any
of the terms or conditions of this Agreement, including any exhibits hereto and
whether or not placed of record, such ambiguity shall not be construed for or
against any party hereto on the basis that such party did or did not author the
same.

                                          27

<PAGE>

    13.16     WAIVER OF JURY TRIAL.  SELLER AND PURCHASER DO HEREBY IRREVOCABLY
WAIVE, TO THE FULLEST EXTENT PERMITTED BY LAW, ANY AND ALL RIGHT TO A TRIAL BY
JURY IN ANY ACTION, SUIT OR OTHER LEGAL PROCEEDING BASED UPON, ARISING OUT OF OR
RELATING TO THIS AGREEMENT OR THE TRANSACTIONS CONTEMPLATED HEREBY.

    13.17     PUBLICITY.  Seller and Purchaser shall consult with each other
with regard to all publicity and other releases and disclosures to be made prior
to, at or after Closing concerning this Agreement and the transactions
contemplated hereby, which are not otherwise expressly permitted by the
Confidentiality Agreement, and, except as required by applicable law or the
applicable rules or regulations of any governmental body or stock exchange,
neither party shall make any disclosure or issue any publicity or other release
without the prior written consent of the other party, which consent shall not be
unreasonably withheld or delayed.


    13.18  ACCOUNTING.

    A.   Seller shall deliver to Purchaser on or before the fourth business day
         prior to Closing the Preliminary Settlement Statement setting forth
         any adjustments to the Purchase Price provided for in or required by
         this Agreement, using estimates where actual amounts are not known at
         the Closing.  The Preliminary Settlement Statement shall be prepared
         in accordance with this Agreement and with standard industry and
         accounting practices.  In connection with the preparation of the
         Preliminary Settlement Statement, the Purchase Price shall be (1)
         increased by (a) the costs and expenses that are attributable to the
         Subject Properties for the period from the Effective Time to the
         Closing Date that are paid by Seller, and (b) other amounts due Seller
         and contemplated hereby, and (2) reduced by (a) proceeds received by
         Seller for hydrocarbons attributable to the Subject Properties
         produced after the Effective Time, and (b) other amounts due Purchaser
         and contemplated hereby.

    B.   As soon as reasonably practicable after the Closing, but not later
         than ninety (90) days thereafter Seller shall prepare, in accordance
         with this Agreement and with standard industry and accounting
         practices, and deliver to Purchaser, a final accounting statement
         showing the proration and calculation of credits and payment
         obligations of Purchaser and Seller hereunder.  As soon as reasonably
         practicable thereafter, Purchaser shall deliver to Seller a written
         report containing any changes that Purchaser  proposes to be made to
         such statement.  The parties shall use their best efforts to reach
         agreement (the "FINAL ACCOUNTING") on the final accounting statement
         on or before the 120th day after the Closing Date (such date the
         "FINAL ACCOUNTING DATE", whether or not Seller and Purchaser have
         agreed on the Final Accounting).  Once the Final Accounting has been
         agreed to by Purchaser and Seller, there shall be no further
         adjustments to the Purchase Price.  At Closing, Purchaser shall assume
         and acquire all rights, obligations and

                                          28

<PAGE>

         liabilities relating to the purchased Assets whether arising before or
         after the Effective Time, as provided in Article 9.

    13.19     OPERATORSHIP.  Seller does not represent to Purchaser that
Purchaser will automatically succeed to the operatorship of any given Subject
Property as to which Seller is currently the operator.  Purchaser recognizes and
agrees that Purchaser will be required to comply with applicable operating
agreements, unit operating agreements or other similar contracts relating to any
elections or other selection procedures in order to succeed Seller as operator.

    13.20     HSR ACT.  The parties shall exercise their best efforts to file
(or will cause their ultimate parent entities to file) with the United States
Federal Trade Commission and the United States Department of Justice all
notifications and reports required for the transaction contemplated hereby under
the Hart-Scott-Rodino Antitrust Improvements Act of 1976 ("HSR ACT"), and shall
request early termination of the prescribed waiting period.  Both parties shall
use their best efforts to promptly supply any supplemental or additional
information which may be requested in connection therewith pursuant to the HSR
Act and shall comply in all material respects with the requirements of the HSR
Act.  Closing of the transaction contemplated hereby shall not occur unless and
until all necessary filings and notifications under the HSR Act have been made,
including the provision of any required additional information or documents, and
the waiting period referred to in such Act shall have expired or terminated.

    13.21     SELLER'S EMPLOYEES.  Purchaser will interview and evaluate in
accordance with its normal employment procedures those Persons employed by
Seller in connection with the Subject Properties and identified by letter of
even date herewith from Seller to Purchaser who desire to be considered for
employment by Purchaser, and will offer in writing employment to those Persons
for whom Purchaser in its sole discretion determines a need.  If Purchaser fails
to offer such employment to all of such Persons, Purchaser shall not, as a
result of such failure, otherwise be in default under this Agreement, but shall
be required to reimburse Seller for severance benefits paid by Seller to each
such Person not offered employment by Purchaser; PROVIDED, that such
reimbursement shall not exceed that amount determined by multiplying each such
employee's normal weekly wage by ten (10).  Persons offered employment with
Purchaser will be offered employment at their current work location with
compensation and benefits comparable to those provided to Purchaser's current
employees performing similar tasks, or, if none, with compensation and benefits
comparable to those provided by Seller, and Purchaser, with respect to its
policies and procedures, will (i) give all such Persons credit for years of
employment with Seller or its Affiliates, and (ii) waive or cause the waiver of
all waiting periods required before new employees of Purchaser are normally
entitled to Purchaser's employee benefits of any and all nature, or make other
accommodations equivalent to such a waiver.  Such offers shall be made prior to
Closing, but shall be contingent upon the occurrence of Closing and such
employment shall not commence until Closing.  If any such Person employed by
Purchaser is terminated by Purchaser within six (6) months of Closing, Purchaser
shall pay such Person a severance benefit equal to the amount determined by
multiplying each such employee's normal weekly wage by ten (10).  Purchaser
shall have no obligation under this Section 13.21

                                          29

<PAGE>

with respect to Persons offered employment by Purchaser pursuant to this Section
13.21 who decline such employment.

    13.22     OPINIONS OF COUNSEL.  Upon execution hereof, Purchaser and Seller
shall deliver to the other the opinion of  its counsel, reasonably acceptable to
the receiving party, to the effect that (a) such party is authorized and
empowered to enter into and consummate and perform this Agreement, (b) this
Agreement will be binding upon and enforceable against such party according to
its terms, and (c) no further resolutions or approvals of such party are
necessary to authorize and empower such party to consummate this Agreement and
perform hereunder; such opinion to be in form and substance reasonably
acceptable to the receiving party.



                     [REMAINDER OF PAGE LEFT BLANK INTENTIONALLY]


                                          30

<PAGE>

     EXECUTED as of the date first set forth above.

                             SELLER:

                             PARKER & PARSLEY DEVELOPMENT L.P.,
                               by Parker & Parsley Petroleum USA, Inc.,
                                  General Partner


                             By: /s/ T.A. Leach
                                ----------------------------------------------
                                T. A. Leach, Senior Vice President

                             PARKER & PARSLEY PRODUCING L.P.,
                               by Parker & Parsley, Inc., General Partner


                             By: /s/ T.A. Leach
                                ----------------------------------------------
                                T.A. Leach, Senior Vice President

                             PURCHASER:

                             COSTILLA PETROLEUM CORPORATION


                             By: /s/ Michael J. Grella
                                ----------------------------------------------
                                Michael J. Grella, President

                             COSTILLA ENERGY, L.L.C.


                             By: /s/ Cadell S. Liedtke
                                ----------------------------------------------
                                Cadell S. Liedtke, Chief Executive Officer


                             By: /s/ Henry G. Musselman
                                ----------------------------------------------
                                Henry G. Musselman, Vice President



                                          31


<PAGE>








                             PURCHASE AND SALE AGREEMENT

                                    by and between

                          PARKER & PARSLEY DEVELOPMENT L.P.

                                         and

                           PARKER & PARSLEY PRODUCING L.P.

                                         AND

                         PARKER & PARSLEY GAS PROCESSING CO.

                                      as Seller

                                         and

                            COSTILLA PETROLEUM CORPORATION

                                         and

                               COSTILLA ENERGY, L.L.C.

                                     as Purchaser



                                    MARCH 8, 1996







<PAGE>


                                  TABLE OF CONTENTS

ARTICLE 1.  SALE AND PURCHASE .............................................   1
    1.1  Effective Time ...................................................   1
    1.2  Sale and Purchase ................................................   1
    1.3  Excluded Assets ..................................................   2
    1.4  Pipeline .........................................................   2

ARTICLE 2.  CONSIDERATION .................................................   3
    2.1  Consideration ....................................................   3
    2.2  Manner of Payment ................................................   3
    2.3  Like Kind Exchange Option ........................................   3
    2.4  Deposit ..........................................................   3

ARTICLE 3.  DEFECTS .......................................................   3
    3.1  Definition of Acceptable Title ...................................   3
    3.2  Definition of Permitted Encumbrances .............................   4
    3.3  Environmental and Physical Assessment ............................   5
    3.4  Identified Claims ................................................   6
    3.5  Notice of Defects ................................................   6
    3.6  Remedy for Defects ...............................................   7
    3.7  Preferential Purchase Rights and Consents to Assign ..............   7

ARTICLE 4.  SELLER'S REPRESENTATIONS,WARRANTIES AND COVENANTS .............   8
    4.1  Existence ........................................................   8
    4.2  Existence ........................................................   8
    4.3  Power ............................................................   8
    4.4  Authorization ....................................................   9
    4.5  Brokers ..........................................................   9
    4.6  Foreign Person ...................................................   9
    4.7  No Liens .........................................................   9
    4.8  Valid Agreements .................................................   9
    4.9  No Reservations ..................................................   9
    4.10 Permits ..........................................................   9
    4.11 Compliance with Law ..............................................   9
    4.12 Taxes ............................................................   9
    4.13 Access to Records ................................................   9
    4.14 No Call ..........................................................  10
    4.15 Litigation .......................................................  10
    4.16 No "Take-or-Pay" Commitments .....................................  10
    4.17 Royalties ........................................................  10
    4.18 Access ...........................................................  10
    4.19 NGPA Status ......................................................  10
    4.20 Use of Assets ....................................................  10
    4.21 Take or Pay; Discounts ...........................................  10
    4.22 FERC .............................................................  10
    LIMITATION AND DISCLAIMER OF REPRESENTATIONS AND WARRANTIES ...........  11
    4.23 Maintenance of Assets ............................................  11
    4.24 No Encumbrances ..................................................  12
    4.25 Operations .......................................................  12

<PAGE>

ARTICLE 5.  REPRESENTATIONS, WARRANTIES AND COVENANTS OF PURCHASER ........  13
    5.1  Existence ........................................................  13
    5.2  Power ............................................................  13
    5.3  Authorization ....................................................  13
    5.4  Brokers ..........................................................  14
    5.5  Investment Intent ................................................  14
    5.6  Additional Interests .............................................  14

ARTICLE 6.  SELLER'S CONDITIONS OF CLOSING ................................  14
    6.1  Representations ..................................................  14
    6.2  Performance ......................................................  14
    6.3  Officer's Certificate ............................................  14
    6.4  Pending Matters ..................................................  14
    6.5  HSR Act ..........................................................  14

ARTICLE 7.  PURCHASER'S CONDITIONS OF CLOSING .............................  15
    7.1  Representations ..................................................  15
    7.2  Performance ......................................................  15
    7.3  Officer's Certificate ............................................  15
    7.4  Pending Matters ..................................................  15
    7.5  HSR Act ..........................................................  15
    7.6  Pipeline .........................................................  15

ARTICLE 8.  CLOSING .......................................................  15
    8.1  Time and Place of Closing ........................................  15
    8.2  Closing Obligations ..............................................  15

ARTICLE 9.  POST-CLOSING OBLIGATIONS ......................................  16
    9.1  Receipts and Credits; Suspense Funds .............................  16
    9.2  Costs and Liabilities; Indemnity .................................  16
    9.3  Further Assurances ...............................................  18
    9.4  Delivery of Records ..............................................  18

ARTICLE 10.  TERMINATION ..................................................  19
    10.1 Right of Termination .............................................  19
    10.2 Effect of Termination ............................................  19

ARTICLE 11.  TAXES ........................................................  20
    11.1 Apportionment of Ad Valorem and Property Taxes ...................  20
    11.2 Sales Taxes ......................................................  20
    11.3 Other Taxes ......................................................  20
    11.4 Cooperation ......................................................  20

ARTICLE 12.  PHYSICAL CONDITION OF THE ASSETS .............................  20
    12.1 Prior Use of Assets ..............................................  20
    12.2 Assumption of Assets in Present Condition ........................  20
    12.3 Casualty Loss ....................................................  21

<PAGE>

ARTICLE  13.  MISCELLANEOUS ...............................................  21
    13.1  Governing Law ...................................................  21
    13.2  Entire Agreement ................................................  21
    13.3  Waiver ..........................................................  21
    13.4  Captions ........................................................  22
    13.5  Assignability ...................................................  22
    13.6  Notices .........................................................  22
    13.7  DTPA Waiver .....................................................  23
    13.8  Expenses ........................................................  23
    13.9  Severability ....................................................  23
    13.10 Damages .........................................................  23
    13.11 No Third Party Beneficiary ......................................  23
    13.12 Survival ........................................................  23
    13.13 Counterparts ....................................................  24
    13.14 Certain Definitions .............................................  24
    13.15 Construction of Ambiguity .......................................  24
    13.16 Waiver of Jury Trial ............................................  24
    13.17 Publicity .......................................................  24
    13.18 Accounting ......................................................  24
    13.19 Operatorship ....................................................  25
    13.20 HSR Act .........................................................  25
    13.21 Seller's Employees ..............................................  25
    13.22 Opinions of Counsel .............................................  25

Disclosure Schedule
Schedule I    -    Excluded Equipment
Exhibit "A"   -    Subject Properties
Exhibit "A-1" -    Leasehold Estates
Exhibit "A-2" -    Certain Personal Property
Exhibit "A-3" -    Pipeline Map
Appendix I    -    Additional Interests


<PAGE>

                             PURCHASE AND SALE AGREEMENT


    This PURCHASE AND SALE AGREEMENT (this "AGREEMENT") is made as of March 8,
1996, by and between PARKER & PARSLEY DEVELOPMENT L.P., a Texas limited
partnership ("PPDLP"), PARKER & PARSLEY PRODUCING L.P., a Delaware limited
partnership ("PPPLP"), and PARKER & PARSLEY GAS PROCESSING CO., a Delaware
corporation acting as the Trustee of Three Rivers Pipeline Business Trust, a
Pennsylvania business trust ("PPGP", and, together with PPDLP and PPPLP,
"SELLER"), and COSTILLA PETROLEUM CORPORATION, a Texas corporation ("CPC") and
COSTILLA ENERGY, L.L.C., a Texas limited liability company ("CELLC", and,
together with CPC, "PURCHASER").


                                      RECITALS:

    WHEREAS, Seller has agreed to sell and Purchaser has agreed to purchase
Seller's interests in certain oil and gas leases, agreements, contracts, real
property, personal property, equipment and related rights.

    NOW, THEREFORE, for good and valuable consideration and for the mutual
covenants contained herein, Seller and Purchaser hereby agree as follows:

                            ARTICLE 1.  SALE AND PURCHASE

    1.1  EFFECTIVE TIME.  The effective time and date of the purchase and sale
contemplated hereby shall be 7:00 a.m., January 1, 1996, at the site of the
respective Subject Properties (the "EFFECTIVE TIME").

    1.2  SALE AND PURCHASE.  Subject to the terms and conditions herein
contained, at Closing and as of the Effective Time, Seller shall sell, assign,
transfer and convey to Purchaser,  and Purchaser shall purchase and receive, the
following described assets, less and except the Excluded Assets (the "ASSETS"):

    (a)  all interest of Seller as of the Effective Time (the "SALE INTEREST")
         in and to (1) the wells, leases and/or units described in Exhibit "A"
         attached hereto and incorporated herein; (2) the oil, gas and mineral
         leasehold estates and fee estates appurtenant to wells, leases and/or
         units described in Exhibit "A" attached hereto, upon which such wells
         are located or with respect to which such wells are associated,
         including the leasehold estates described in Exhibit "A-1"; (3) all
         other interests in oil, gas and other minerals of whatever nature
         appurtenant to wells, leases and/or units described in Exhibit "A"
         attached hereto, including, without limitation, all fee estates, fee
         mineral and royalty interests, working interests, farmout rights and
         overriding royalty interests; (4) any pooled, communitized or unitized
         acreage of which any such leasehold, fee or other interest is a part
         and all of the rights incident thereto; (5) the gas processing plant
         and appurtenant lands located in Karnes County, Texas, known as the
         Person Processing Plant; and (6) that certain 8-inch pipeline
         extending approximately 119 miles from a point 2.5 miles each of
         Mobil Pipe Line Company's terminal near Midland, Pennsylvania to a
         point at Mobil Pipe Line Company's terminal near Hollidaysburg,
         Pennsylvania and located in Allegheny, Beaver, Blair, Cambria, Indiana
         and Westmoreland Counties, Pennsylvania, and that certain 4-inch
         lateral line extending from such 8-inch line to McKees Rocks,
         Allegheny County, Pennsylvania, known as the Three Rivers Pipeline and
         as depicted on Exhibit "A-3" attached hereto (the "PIPELINE"),


                                          1

<PAGE>


         together with all appurtenant easements, rights-of-way, easements,
         surface leases, fee estates and other real property rights (reference
         being hereby made to Seller's records and files located at 303 W.
         Wall, Suite 101, Midland, Texas, and at Seller's Yatesboro Field
         office, Yatesboro, Pennsylvania, for a more complete description of
         said leases, leasehold and fee estates and interests, plant and
         pipeline)  (collectively, the "SUBJECT PROPERTIES");

    (b)  to the extent attributable or allocable to the Subject Properties, all
         interest of Seller (including, without limitation, leasehold) as of
         the Effective Time in and to: (1) all wells (including but not limited
         to the wells described in Exhibit "A" and all other oil, gas,
         injection and water wells), equipment, lease equipment, signage,
         gathering pipelines, gas facilities, gathering systems, gathering,
         storage, distribution, treating, processing and disposal facilities
         and tanks, vehicles, tools, buildings, inventory and all other real or
         tangible personal property and fixtures which are located on or
         directly and solely related to the Subject Properties, including,
         without limitation, items of personal property described in Exhibit
         "A-2"; (2) all oil, gas, mineral and other hydrocarbon substances
         produced on or after the Effective Time; (3) to the extent the same
         are assignable or transferable by Seller, all orders, contracts, title
         opinions and documents, abstracts of title, leases, deeds, unitization
         agreements, pooling agreements, operating agreements, division of
         interest statements, participation agreements, gas purchase, sale,
         transportation and processing agreements, and all other agreements and
         instruments; (4) all surface leasehold and fee estates, easements,
         rights-of-way, licenses, authorizations, permits and similar rights
         and interests, subject to the rights of third parties; (5) except as
         expressly provided otherwise herein, all warranties, covenants,
         indemnities  and representations from third parties, and all claims,
         rights and causes of action against third parties, asserted and
         unasserted, known and unknown; (6) to the extent assignable and
         subject to the rights of third parties, lease files, land files,
         operating files, well files, oil and gas sales contract files, gas
         processing files, logs, test data, production histories, division
         order files, abstracts, title files and materials, and all other
         books, files and records (the "RECORDS"), and all rights thereto,
         subject to the rights of third parties; and (7) all other rights,
         privileges, benefits and powers conferred upon the owner and holder of
         interests in the Subject Properties; and

    (c)  to the extent necessary for the ownership, use or development of the
         Subject Properties and subject to the rights of third parties, the
         right of ingress and egress with respect to the SF Interests (as
         defined below).

    1.3  EXCLUDED ASSETS.  Notwithstanding anything in this Agreement to the
contrary, the Assets do not include and Purchaser agrees and acknowledges that
each Seller respectively  has reserved from the Assets and hereby reserves unto
itself any and all rights, titles and interests in and to (a) (1) fee, fee
mineral and royalty interests which were conveyed to PPPLP by all or any of
Santa Fe Energy Resources, Inc. ("SFER"), Santa Fe Energy Operating Partners,
L.P. ("SFEOP") or SFER Properties-A, Inc. ("SFERP-A") or any of their respective
Affiliates, and (2) or arising under that certain Exploration Agreement dated
April 8, 1994, between SFEOP and PPPLP and all property rights, grants, and
interests created, made or evidenced by such Exploration Agreement
(collectively, the "SF INTERESTS"), (b) the right of ingress and egress for the
purpose of mining, drilling, exploring, operating, holding, producing and
developing the SF Interests for oil, gas, minerals and other hydrocarbon
substances, (c) seismic, geologic and geophysical records and data not expressly
described in Section 1.2(b)(6) above, and (d) the equipment described on
Schedule I attached hereto ((a) through (d), collectively, the "EXCLUDED
ASSETS").


                                          2

<PAGE>


    1.4  PIPELINE.  At Purchaser's option and subject to Seller's written
consent given hereafter, which may be withheld or denied for any or no reason,
Purchaser may elect to acquire Three Rivers Pipeline Business Trust, a
Pennsylvania business trust, for the Agreed Value, as herein defined, but which
for all purposes hereunder shall be deemed to be $3,500,000.

                              ARTICLE 2.  CONSIDERATION

    2.1  CONSIDERATION.   As consideration for this Agreement and the transfer
of the Assets, at Closing, Purchaser shall pay to Seller $45,098,590 (the
"PURCHASE PRICE"), as may be  adjusted pursuant hereto (the "ADJUSTED PURCHASE
PRICE").  On or before April 8, 1996, Purchaser will provide to Seller an
allocation of the Purchase Price among the Subject Properties based upon
Purchaser's engineered value for each such property as of the Effective Date
(the "AGREED VALUE").

    2.2  MANNER OF PAYMENT.  At Closing, except as provided in the following
Section 2.3, Purchaser shall pay Seller or Seller's designee the Adjusted
Purchase Price by wire transfer of immediately available funds as follows:

              Account:            Parker & Parsley Development L.P.
              Account No:         1290288845
                                  NationsBank of Texas, N.A.
              ABA Routing No:     111000025
              Attention:          Frank Stowers
                                  NationsBank of Texas-Midland
                                  (915) 685-2179

    2.3  LIKE KIND EXCHANGE OPTION.  Seller and Purchaser hereby agree that
Seller, in lieu of the sale of the Assets to Purchaser for the cash
consideration provided herein, shall have the right at any time prior to Closing
to assign all or a portion of its rights under this Agreement to a qualified
intermediary in order to accomplish the transactions contemplated hereby in a
manner that will comply, either in whole or in part, with the requirements of a
like kind exchange pursuant to Section 1031 of the Internal Revenue Code of
1986, as amended ("CODE").  In the event Seller assigns its rights under this
Agreement pursuant to this Section 2.3, Seller agrees to notify Purchaser in
writing of such assignment before Closing.  If Seller assigns its rights under
this Agreement, Purchaser agrees to (i) consent to Seller's assignment of its
rights in this Agreement, (ii) deposit the Adjusted Purchase Price with the
qualified escrow or qualified trust account designated by Seller at Closing, and
(iii) take such further actions, at Seller's cost, as are reasonably required to
effectuate the transactions contemplated hereby pursuant to Code Section 1031,
but, in so acting, Purchaser shall have no liability to any party in connection
with such actions.  All risks associated with any like kind exchange and
compliance thereof with applicable laws, rules and regulations shall be the sole
responsibility of Seller, and Seller agrees to indemnify and hold Purchaser
harmless from and against all costs, expenses, liabilities and obligations which
arise as a result of Purchaser's agreement contained in this Section 2.3.

    2.4  DEPOSIT. Purchaser will pay to Seller (a) $500,000 contemporaneously
with the execution of this Agreement ("FIRST INSTALLMENT"), and (b) an
additional $1,500,000 on or before 11:00 a.m., March 18, 1996 ("SECOND
INSTALLMENT") as a performance deposit hereunder, each of which shall be wired
in accordance with the instructions contained in Section 2.2 above.  If Closing
occurs, such amount and all interest accrued thereon (the "DEPOSIT") shall be
applied to reduce the Adjusted Purchase Price.  If Closing does not occur, the
Deposit shall be applied as provided in Section 10.2.  Until disposed of in
accordance with the terms of this Agreement, the Deposit shall be held and
invested by Seller in marketable obligations issued or unconditionally
guaranteed by the United States


                                          3

<PAGE>


of America or an instrumentality or agency thereof and entitled to the full
faith and credit of the United States of America, or in money market and/or
mutual funds that invest solely in such obligations.

                                 ARTICLE 3.  DEFECTS

    3.1  DEFINITION OF ACCEPTABLE TITLE.  As used herein, the term "ACCEPTABLE
TITLE" shall mean, as to the Subject Properties, such right, title and interest
that (a) entitles Seller to receive not less than the net revenue interest set
forth in Exhibit "A" of all oil, gas and associated liquid and gaseous
hydrocarbons produced, saved and marketed from the respective Subject
Properties, (b) obligates Seller to bear costs and expenses relating to the
maintenance, development, and operation of all wells located on the respective
Subject Properties in an amount not greater than the working interest set forth
in Exhibit "A", unless there is a corresponding increase in the applicable net
revenue interest, and (c) except for Permitted Encumbrances, is free and clear
of all liens, claims and encumbrances; PROVIDED, however that (i) the presence
of a preferential right to purchase provision shall not be considered to be a
Defect (as defined in Section 3.5 below); and (ii) if Purchaser demonstrates
before or after Closing, subject to Section 13.12 below, that Seller does not
have or cannot convey Acceptable Title to a well described in Exhibit "A" and,
if so demonstrated after Closing, that Purchaser did not receive at Closing an
adjustment to the Purchase Price or other consideration on account of such
matter, and if Seller owns fee mineral interests or other interests underlying
the applicable proration or spacing unit on which such well is located, Seller
shall resolve such matter by, at Seller's option, either (1) granting a lease
(on mutually acceptable terms) on all or part of such interests, or (2)
conveying (which conveyance may be limited in term, similar to an oil and gas
lease) all or part of such interests to Purchaser and, if so resolved, such
matter shall not be considered a Defect for any purpose hereunder if the
interest so conveyed, or leased, will (after considering, in the case of a
lease, the royalty reserved to Seller under the lease) be sufficient so that,
after giving effect thereto, such matter will no longer exist (a "FURTHER
CONVEYANCE"); PROVIDED, however, that such Further Conveyance shall be limited
to depths from the surface of the ground down to the deepest producing zone from
which production is being obtained (from the subject well) at the Effective Time
insofar as such depths underlie the proration or spacing unit attributable to
such well. Purchaser acknowledges and agrees that any net revenue interests and
working interests reflected on Exhibit "A" are for the convenience of Seller and
Purchaser and included solely for the purpose of determining Acceptable Title
prior to Closing; Seller does not and shall not represent or warrant that the
Sale Interest is equal to any such interests in any respect, but agrees that (i)
for purposes of determining Defects prior to Closing, with respect to those
Subject Properties listed on Exhibit "A" with "0.0000" "APO" interests, the
"APO" interests shall be deemed to be the same as the corresponding "BPO"
interests, and (ii) Purchaser may assert as a Title Defect (as defined in and
pursuant to Section 3.5 below) any matter reasonably expected to reduce the net
revenue interest assigned to such Subject Property or any matter reasonably
expected to increase the working interest assigned to such Subject Property
unless there is a corresponding increase in the applicable net revenue interest.


    3.2  DEFINITION OF PERMITTED ENCUMBRANCES.  As used herein, the term
"PERMITTED ENCUMBRANCES" shall mean the following items, provided none of the
following items shall operate to increase the working interest of Seller as set
forth in Exhibit "A" for any of the Subject Properties, without a corresponding
increase in the applicable net revenue interest, or decrease the net revenue
interest of Seller set forth in Exhibit "A" for any of the Subject Properties:

    (a)  lessors' royalties, overriding royalties, production payments,
         reversionary interests and similar burdens;

    (b)  division orders and sales contracts;


                                          4

<PAGE>


    (c)  preferential rights to purchase not identified in writing to Seller
         pursuant to Section 3.7 below, or, if so identified, with respect to
         which (1) waivers are obtained from the appropriate parties, (2) the
         appropriate time period for asserting such rights has expired without
         an exercise of such rights, or (3) appropriate parties have exercised
         such rights and the Purchase Price has been adjusted by the Agreed
         Value ("PREFERENTIAL RIGHTS");

    (d)  rights to consent to assignments required by this Agreement held by
         Persons other than governmental entities and not identified in writing
         to Seller pursuant to Section 3.7 below, or, if so identified, with
         respect to which (1) waivers or consents are obtained from the
         appropriate parties, or (2) the prescribed time period for denying
         such consent has expired;

    (e)  materialman's, mechanic's, repairman's, employee's, contractor's,
         operator's, tax, and other similar liens or charges arising in the
         ordinary course of business for obligations that are not delinquent
         and that will be paid and discharged in the ordinary course of
         business;

    (f)  rights to consent by, required notices to, filings with, or other
         actions by governmental entities in connection with the sale or
         conveyance of oil and gas leasehold and fee estates or interests
         therein, which consents, notices, filings and/or other actions are
         customarily obtained after closing;

    (g)  easements, rights-of-way, servitudes, permits, surface leases and
         other rights in respect of surface operations affecting the Assets
         which in the aggregate are not such as to interfere materially with
         the operation or use of any of the Subject Properties or materially
         reduce the value thereof;

    (h)  rights reserved to or vested in any governmental, statutory or public
         authority to control or regulate any of the Assets in any manner, and
         all applicable laws, rules and orders of any governmental authority
         affecting the Assets which in the aggregate are not such as to
         interfere materially with the operation or use of any  of the Subject
         Properties or materially reduce the value thereof;

    (i)  operating agreements, unit agreements, unit operating agreements,
         pooling agreements and pooling designations affecting the Subject
         Properties which are of public record or contained in the Records or
         otherwise available to Purchaser and all actions taken or operations
         occurring in the normal course of business pursuant to such
         instruments;

    (j)  Title Defects that Purchaser may have expressly waived in writing or
         which are deemed to have been waived pursuant to Section 3.6;

    (k)  all conveyances, reservations and exceptions of public record or
         contained  in the Records affecting the Assets which in the aggregate
         are not such as to interfere materially with the operation or use of
         any of the Subject Properties or materially reduce the value thereof;
         and

    (l)  all other liens, charges, encumbrances, contracts, agreements,
         instruments, obligations, defects and irregularities affecting the
         Assets which in the aggregate are not such as to interfere materially
         with the operation or use of the affected Subject Properties or
         materially reduce the value thereof.


                                          5

<PAGE>


    3.3  ENVIRONMENTAL AND PHYSICAL ASSESSMENT.   Purchaser shall have the
right to make an environmental and other physical assessment of the Assets
during the period ("EXAMINATION PERIOD") beginning on the date of execution of
this Agreement and ending at noon on May 20, 1996.  During Seller's normal
business hours, Purchaser and its Representatives shall have the right to enter
upon the Assets and all buildings and improvements thereon, inspect the same,
conduct soil and water tests and borings, and generally conduct such tests,
examinations, investigations and studies as may be reasonably necessary or
appropriate for the preparation of appropriate environmental and other reports
relating to the Assets, their condition, and the presence of wastes or
contaminants.  Seller shall be provided 48 hours prior notice of  such
activities and shall have the right to (i) witness all such tests and
investigations, (ii) receive an equal distribution of all samples taken by
Purchaser and its Representatives, and (iii) prohibit such tests and
investigations which it reasonably believes could materially damage its
properties or business interests; PROVIDED, that Purchaser shall have the right
to exclude the Asset subject to such prohibition from this Agreement by written
notice delivered with any Notice of Defects, in which case the Purchase Price
shall be reduced by the Agreed Value.  Purchaser shall keep any data or
information acquired by all such examinations and the results of all analyses of
such data and information strictly confidential and not disclose any of the same
to any Person unless otherwise required by law or regulation and then only after
written notice to Seller of the need for disclosure and the identity of all
intended recipients.  Seller hereby grants Purchaser access to the Assets to
conduct its environmental and other physical assessment upon the condition that,
in accordance with Section 9.2, Purchaser hereby indemnifies and holds Seller
and its Affiliates and their respective Representatives harmless from and
against any and all claims for or related to personal injury or property damage
arising out of or as a result of the activities of Purchaser or its
Representatives on the Assets in conducting such environmental and physical
assessments.  If during the Examination Period, Purchaser determines in good
faith that (i) there is a condition or circumstance which constitutes a
violation of applicable law or regulation, or (ii) there is a claim, demand,
filing, investigation, action, suit or other legal or administrative proceeding
asserted or otherwise initiated by a governmental authority and arising from or
related to the Subject Properties or the ownership or operation of any thereof
("ENVIRONMENTAL DEFECT"), Purchaser may include notice of such Defect in any
Notice of Defects delivered hereunder, and the value of  such Defect asserted by
Purchaser shall not be limited to the value of the Subject Properties so
affected; PROVIDED, that any such matter not included in a Notice of Defects
shall be and hereby is waived by Purchaser.

    3.4  IDENTIFIED CLAIMS.  During the Examination Period and in accordance
with Section 4.12, Seller shall make available to Purchaser for examination and
copying (at Purchaser's cost) any of the Records and Seller's accounting records
relating to the Assets as Purchaser may reasonably request.  Seller shall also
permit Purchaser's Representatives to consult with Seller's employees and
Seller's independent contractors who have knowledge concerning the Assets during
normal business hours regarding such records; PROVIDED, that such consultation
shall not unreasonably disrupt the performance by such employee or independent
contractor of his or its duties with Seller.  If during the Examination Period,
Purchaser determines in good faith that (i) royalties, rentals or other payments
due in respect of the Assets prior to the Effective Time have not been paid
(except for those amounts in suspense), or (ii) there are unsatisfied claims,
demands, liabilities or obligations in respect of the Assets based upon
omissions, events or occurrences prior to the Effective Time (collectively,
"IDENTIFIED CLAIMS"), Purchaser may include notice of such Identified Claims in
any Notice of Defects delivered hereunder; PROVIDED, that any such matter not
included in a Notice of Defects shall be and hereby is waived by Purchaser.

    3.5  NOTICE OF DEFECTS.  If any matter is discovered by Purchaser that, in
Purchaser's reasonable, good faith opinion, would (a) cause any of the Sale
Interest not to be Acceptable Title (a "TITLE DEFECT"); (b) constitute a breach
of Seller's representations, warranties and agreements contained herein (a
"CONTRACT DEFECT"); (c) constitute an Environmental Defect; or (d) constitute an


                                          6

<PAGE>


Identified Claim ((a) through (d) to the extent that each such matter exceeds an
individual value of $5,000, individually, a "DEFECT", and collectively, the
"DEFECTS"), then Purchaser may provide written notice (a "NOTICE OF DEFECTS")
thereof actually delivered to Seller not later than noon, May 20, 1996;
PROVIDED, however, that any notice concerning a Contract Defect not discoverable
from an examination of the Records, public records, Purchaser's records, the
records of any purchaser of production attributable to the Subject Properties or
a physical inspection of the Assets may be delivered to Seller on or before noon
of the business day immediately before the Closing Date, and that, if so
delivered, Purchaser's sole remedy therefor shall be as provided in Section 3.6,
with the procedure therein provided applicable thereto the same as if such
Contract Defect had been included in any Notice of Defects delivered not later
than noon, May 20, 1996 (i.e., the value of any such Contract Defect shall be
included in the value of any other Defects included in a Notice of Defects, or,
if no Notice of Defects has been provided, then such Contract Defect only may be
included in a Notice of Defects then given to Seller). A Notice of Defects shall
specifically identify the Defect and include (i) the Purchaser's purported value
of each specific Defect, (ii) an identification of each affected Asset, (iii)
Purchaser's basis for determining the existence and value of such Defect,
together with all associated reports, opinions, data, valuations, assessments,
conclusions and supporting calculations, and (iv) Purchaser's statement of steps
necessary to cure each such Defect to its satisfaction, all of which shall be
kept strictly confidential by Seller, except to the extent required by law,
regulation or order of any court or other governmental authority or as may be
necessary to address Defects identified in a Notice of Defects.

    3.6  REMEDY FOR DEFECTS.  In Seller's sole discretion, but without
obligation, it may, at its sole cost, take such steps as are reasonably
necessary to cure Defects identified in a Notice of Defects.  In the event
Seller is unable or elects not to cure any or all Defects, Seller and Purchaser
may, at Seller's option, meet and use their best efforts to agree in good faith
on the validity of each Defect claim and the need for and amount of any mutually
acceptable Purchase Price adjustment.  Purchaser's asserted Title Defect
adjustments shall be made with reference (as a maximum) to the Agreed Value for
each affected Asset.  If the parties cannot agree on the need for or the amount
of a claimed Purchase Price adjustment, Purchaser shall accept and purchase the
Assets, including any Asset subject to a Defect, as provided herein; PROVIDED,
however, that (i) if the aggregate net amount of Purchase Price adjustments
asserted by Purchaser, PLUS the amount of any uninsured Casualty Losses and
Casualty Losses not fully covered by insurance (to the extent of such deficiency
only), PLUS the value of any of the Subject Properties (with reference to the
Agreed Value thereof as a maximum) taken in condemnation or under the right of
eminent domain prior to the end of the Examination Period, or with respect to
which proceedings for such purposes shall be pending or threatened in writing at
such time, equals or exceeds $3,150,000, or (ii) if the aggregate value of
Preferential Rights to be exercised at Closing equals or exceeds 30% of the
Purchase Price, then Seller or Purchaser may, upon written notice to the other,
terminate this Agreement, without liability or further obligation to the other
party, subject to Section 10.2. Seller shall have no obligation hereunder to any
Person to sell, convey, deliver or otherwise transfer all or any part of the
Assets if Purchaser or Seller terminates this Agreement pursuant to the
foregoing clause (ii). Purchaser agrees and acknowledges that Seller has no
obligation to adjust the Purchase Price with respect to Defects.  If Closing
occurs, Purchaser shall be deemed to have waived or assumed any and all claims,
known and unknown, arising from or related to any and all Defects or title to or
other condition of the Assets, including, without limitation, whether or not
identified in a Notice of Defects, and notwithstanding the fact that Seller may
not have cured any such Defect(s) to Purchaser's satisfaction, and Seller shall
have no obligation with respect thereto.  As used in this Agreement, the
"AGGREGATE NET AMOUNT"  of Purchase Price adjustments shall be determined by
subtracting from the value of all Defects asserted by Purchaser (y) the value of
all interests by which Seller's actual interests in the Subject Properties
exceeds the net revenue interests set forth on Exhibit  "A" hereto, and (z) the
value of Defects asserted by Purchaser which are cured or otherwise resolved to
Purchaser's reasonable satisfaction.  If Purchaser provides Seller with a Notice


                                          7

<PAGE>


of Defects, Purchaser shall provide Seller copies of all pertinent portions of
applicable title opinions, data and curative information available to it to
enable the parties to make such determination.

    3.7  PREFERENTIAL PURCHASE RIGHTS AND CONSENTS TO ASSIGN.  Upon written
notification to Seller by Purchaser identifying Persons (and their addresses)
holding preferential rights to purchase affecting the Subject Properties or the
right to consent with respect to any assignments required hereby, other than
such consents of governmental authorities which are usually obtained in the
normal course of business after Closing, actually received by Seller not later
than the earlier of (i) fifteen (15) days prior to the Closing Date, or (ii)
five (5) business days prior to the latest date prior to Closing permitted by
the subject agreement for such notice to be provided,  Seller shall send notice
of this Agreement to all such Persons (y) offering to sell to each such Person
the Subject Properties for which a preferential right is held on and subject to
the terms hereof and for the Agreed Value, or (z) requesting, where appropriate,
consent to any assignment required in connection herewith.  Purchaser shall be
entitled to review and approve the form of all such notices; PROVIDED, that such
approval shall not be unreasonably withheld or delayed.  If, prior to Closing,
any of such Persons asserting a preferential purchase right notifies Seller that
it intends to consummate the purchase of the Subject Properties to which it
holds a preferential purchase right pursuant to the terms and conditions hereof,
then, subject to clause (ii) of Section 3.6 above, such Subject Properties shall
be excluded from the Assets to be conveyed to Purchaser under this Agreement and
the Purchase Price shall be reduced by the Agreed Value; PROVIDED, however, that
if the holder of such preferential right fails to consummate the purchase of
such Subject Properties on the Closing Date, then Seller shall promptly so
notify Purchaser, and Seller shall sell immediately to Purchaser, and Purchaser
shall purchase from Seller, for the Agreed Value and upon the other terms of
this Agreement, the Subject Properties to which the preferential purchase right
was asserted. All Subject Properties for which a preferential purchase right has
not been asserted prior to Closing by the holder of such right, or with respect
to which Closing does not occur on the Closing Date following the assertion of a
preferential purchase right, shall be sold to Purchaser at Closing pursuant and
subject to the provisions of this Agreement.  If one (1) or more of the holders
of any preferential purchase rights notifies Seller subsequent to Closing that
it intends to assert its preferential purchase right, Seller shall give notice
thereof to Purchaser, whereupon Purchaser shall satisfy all such preferential
purchase right obligations of Seller to such holders and shall indemnify and
hold Seller harmless from and against any and all claims, liabilities, losses,
costs and expenses (including, without limitation, court costs and reasonable
attorneys' fees) in connection therewith, and Purchaser shall be entitled to
receive (and Seller hereby assigns to Purchaser all of Seller's rights to) all
proceeds received from such holders in connection with such preferential
purchase rights;  Purchaser shall indemnify and hold harmless Seller from and
against any and all claims, liabilities, losses, costs and expenses (including,
without limitation, court costs and reasonable attorneys' fees) asserted or
incurred at any time (whether before or after Closing) with respect to or
arising directly or indirectly from the claims of any Person to a preferential
purchase right affecting any of the Assets transferred to Purchaser hereunder.


            ARTICLE 4.  SELLER'S REPRESENTATIONS,WARRANTIES AND COVENANTS

    Seller represents, warrants to and covenants with Purchaser that (PROVIDED,
that each of PPDLP and PPPLP, respectively, makes such representations,
warranties and covenants solely with respect to itself and not as to the other):

    4.1  EXISTENCE.  PPDLP and PPPLP are each limited partnerships, duly
formed, validly existing and in good standing under the laws of the State of
Texas and the State of Delaware, respectively.


                                          8

<PAGE>


    4.2  EXISTENCE.  PPGP is a corporation duly organized, validly existing and
in good standing under the laws of the State of Delaware, and is the sole
Trustee of Three Rivers Pipeline Business Trust.  Three Rivers Pipeline Business
Trust is a business trust duly formed, legally existing and in good standing
under the laws of the State of Pennsylvania.

    4.3  POWER.  Seller has the requisite power and authority to enter into and
perform this Agreement and the transactions contemplated hereby. The execution,
delivery and performance of this Agreement by Seller, and the transactions
contemplated hereby, will not (a) violate any provision of Seller's articles or
agreement of limited partnership or other governing documents, (b) conflict
with, result in a breach of, constitute a default (or an event that with the
lapse of time or notice, or both would constitute a default) under any agreement
or instrument to which Seller is a party or by which Seller is bound, (c) to the
best knowledge and belief of Seller, violate any judgment, order, ruling, or
decree applicable to Seller and entered or delivered in a proceeding in which
Seller was or is a named party, or (d) to the best knowledge and belief of
Seller, violate any applicable law, rule or regulation.

    4.4  AUTHORIZATION.   The execution, delivery and performance of this
Agreement and the transactions contemplated hereby have been duly and validly
authorized by all requisite action on the part of Seller.  This Agreement has
been duly executed and delivered on behalf of Seller, and at the Closing all
documents and instruments required hereunder to be executed and delivered by
Seller shall be duly executed and delivered.  This Agreement and such documents
and instruments shall constitute legal, valid and binding obligations of  Seller
enforceable in accordance with their terms subject, however, to the effect of
bankruptcy, insolvency, reorganization, moratorium and similar laws from time to
time in effect relating to the rights and remedies of creditors, as well as to
general principles of equity (regardless of whether such enforceability is
considered in a proceeding in equity or at law).

    4.5  BROKERS.  Seller has incurred no obligation or liability, contingent
or otherwise, for brokers' or finders' fees in respect of the matters provided
for in this Agreement which will be the responsibility of Purchaser, and any
such obligation or liability that might exist shall be the sole obligation of
Seller.

    4.6  FOREIGN PERSON.   Seller is not a "FOREIGN PERSON" within the meaning
of the Code.

    4.7  NO LIENS.  The Assets are not subject to any valid and enforceable
security interests, liens or mortgages.

    4.8  VALID AGREEMENTS.  Material oil and gas leases and other material
contracts and agreements constituting a part of the Assets are valid and in full
force and effect, and Seller is not, or with the lapse of time or giving of
notice or both will not be, in material breach or material default, with respect
to any of its obligations thereunder and no party has given or threatened to
give Seller notice of any material default thereunder.

    4.9  NO RESERVATIONS.  There are no reservations which affect the Assets
other than those currently of public record.

    4.10 PERMITS.  Seller possesses all material licenses, permits,
certificates, orders, approvals and authorizations necessary to own the Assets
and to carry on its business as now being conducted.

    4.11 COMPLIANCE WITH LAW.  Seller is in material compliance with all laws,
ordinances, rules, regulations and orders applicable to the Assets, including,
without limitation, all environmental laws, ordinances, rules, regulations and
orders, except to the extent of any non-compliance that is not reasonably
expected to result in a material adverse affect on the Assets; however, Seller
has not


                                          9

<PAGE>


received any notice of any claimed noncompliance therewith.  Seller is not aware
of any facts, conditions or circumstances in connection with, related to or
associated with the Assets that could reasonably be expected to give rise to any
claim or assertion that Seller, the Assets or the ownership or operation of any
thereof is not in material compliance with any applicable law, rule, regulation,
ordinance, or order of any governmental authority or with any term or conditions
of any applicable permit, license, approval, consent, certificate or other
authorization.

    4.12 TAXES.  All ad valorem, property, production, severance, excise, and
similar taxes and assessments based on or measured by the ownership of property
or the production of hydrocarbons or the receipt of proceeds therefrom
attributable to the Assets that have become due and payable have been properly
and timely paid, except to the extent of any failure that is not reasonably
expected to result in a material adverse effect on the Assets.

    4.13 ACCESS TO RECORDS.  Seller will provide Purchaser through Closing
access to the Records during normal business hours at their place of storage,
and, at Purchaser's cost, will assist Purchaser in obtaining access to and the
right to review and copy Records pertaining to the Subject Properties not in
Seller's possession or control.  From and after the date of the execution of
this Agreement through the Closing Date, Seller shall not add to or remove from
the Records any contracts, instruments, documents or other materials except for
such additions and removals as are done in the ordinary course of business with
respect to ongoing operations.

    4.14 NO CALL.  No Person has any option to purchase or similar right under
any agreement with respect to production attributable to the Assets which could
reasonably be expected to materially and adversely affect the value of  the
Assets, taken as a whole.

    4.15 LITIGATION.  No pending litigation or other proceeding in which Seller
(or its direct predecessor in title) is a named party affects any of the Assets,
and no litigation or other proceeding has been threatened in writing with
respect to any of the Assets, except as described in the Disclosure Schedule to
be attached hereto on or before the fifteenth day hereafter; PROVIDED, that
either Seller or Purchaser may exclude from this Agreement any Assets (other
than the Pipeline with respect to pending proceedings concerning an increase in
existing tariffs) subject to such proceedings and the Purchase Price shall be
reduced by the Agreed Value.

    4.16 NO "TAKE-OR-PAY" COMMITMENTS.  Seller is not obligated by virtue of a
prepayment arrangement, a "TAKE-OR-PAY" arrangement, a production payment or any
other arrangement to deliver hydrocarbons from the Subject Properties at some
future time without then or thereafter receiving full payment therefor.

    4.17 ROYALTIES.  All royalties, rentals and other payments due with respect
to the Assets have been properly and timely paid.

    4.18 ACCESS.  No condition exists upon any of the Subject Properties which
is reasonably expected to restrict access thereto.

    4.19 NGPA STATUS.  Seller has obtained and maintained for its period of
Seller's ownership all approvals and has filed all reports and other matters
necessary to maintain and operate the entirety of the Pipeline under and
pursuant to Section 311 of the Natural Gas Policy Act of 1978 and all rules,
regulations and orders promulgated thereunder (the "NGPA").

    4.20 USE OF ASSETS.  The Pipeline has been used by Seller solely for the
transportation and sale of pipeline quality natural gas.


                                          10

<PAGE>


    4.21 TAKE OR PAY; DISCOUNTS.  The Pipeline is not subject to any contracts
under which it is required to take or pay for, or take and pay for, or purchase
minimum quantities of natural gas.  The Pipeline is not obligated to deliver,
process or transport any gas or products thereof without being entitled to
receive payment at the full agreed upon rate for such delivery, processing or
transportation.

    4.22 FERC.

         (a)  To the extent that the operations of the Pipeline are subject to
              a tariff approved by the Federal Energy Regulatory Commission
              ("FERC"), those operations are in material compliance with such
              tariffs;

         (b)  the Seller has no actual refund obligation imposed in connection
              with the Pipeline under an order issued by FERC; and

         (c)  Seller has not received notice that a customer of the Pipeline
              has made a complaint against the Pipeline which is currently
              pending before FERC, nor notice that any customer has threatened
              to make such a complaint.

             LIMITATION AND DISCLAIMER OF REPRESENTATIONS AND WARRANTIES

THE EXPRESS REPRESENTATIONS AND WARRANTIES OF SELLER CONTAINED IN THIS AGREEMENT
ARE EXCLUSIVE AND ARE IN LIEU OF ALL OTHER REPRESENTATIONS AND WARRANTIES,
EXPRESS, IMPLIED, STATUTORY, OR OTHERWISE, AND, EXCEPT FOR THE REPRESENTATIONS
AND WARRANTIES CONTAINED IN SECTIONS 4.1 THROUGH 4.5 (WHICH SHALL SURVIVE
CLOSING) THE REPRESENTATIONS AND WARRANTIES CONTAINED HEREIN SHALL TERMINATE IN
ALL RESPECTS UPON CLOSING.  ANY ASSIGNMENT AND BILL OF SALE OR OTHER CONVEYANCE
EXECUTED AND DELIVERED PURSUANT HERETO SHALL BE: (a) WITHOUT ANY WARRANTY OR
REPRESENTATION OF TITLE, EITHER EXPRESS, IMPLIED, STATUTORY OR OTHERWISE; (b)
WITHOUT ANY EXPRESS, IMPLIED, STATUTORY OR OTHER WARRANTY OR REPRESENTATION AS
TO THE CONDITION, QUANTITY, QUALITY, FITNESS FOR A PARTICULAR PURPOSE,
CONFORMITY TO MODELS OR SAMPLES OF MATERIALS OR MERCHANTABILITY OF ANY OF THE
ASSETS OR THEIR FITNESS FOR ANY PURPOSE; AND (c) WITHOUT ANY OTHER EXPRESS,
IMPLIED, STATUTORY OR OTHER WARRANTY OR REPRESENTATION WHATSOEVER.  AT CLOSING,
PURCHASER SHALL HAVE INSPECTED OR WAIVED ITS RIGHT TO INSPECT THE RECORDS AND
THE ASSETS FOR ALL PURPOSES AND SATISFIED ITSELF AS TO THE PHYSICAL AND
ENVIRONMENTAL CONDITION OF THE ASSETS, BOTH SURFACE AND SUBSURFACE, INCLUDING
BUT NOT LIMITED TO CONDITIONS SPECIFICALLY RELATED TO THE PRESENCE, RELEASE OR
DISPOSAL OF HAZARDOUS SUBSTANCES.  PURCHASER IS RELYING SOLELY UPON ITS OWN
INSPECTION OF THE ASSETS, AND, PURCHASER SHALL ACCEPT ALL OF THE SAME IN THEIR
"AS IS, WHERE IS" CONDITION.  IN ADDITION, SELLER MAKES NO WARRANTY OR
REPRESENTATION, EXPRESS, IMPLIED, STATUTORY OR OTHERWISE, AS TO THE ACCURACY OR
COMPLETENESS OF ANY DATA, REPORTS, RECORDS, PROJECTIONS, INFORMATION OR
MATERIALS NOW, HERETOFORE OR HEREAFTER FURNISHED OR MADE AVAILABLE TO PURCHASER
IN CONNECTION WITH THIS AGREEMENT, INCLUDING, WITHOUT LIMITATION, ANY
DESCRIPTION OF THE ASSETS, PRICING ASSUMPTIONS, OR QUALITY OR QUANTITY OF
HYDROCARBON RESERVES (IF ANY) ATTRIBUTABLE TO THE ASSETS OR THE ABILITY OR
POTENTIAL OF THE ASSETS TO PRODUCE HYDROCARBONS OR THE ENVIRONMENTAL CONDITION
OF THE ASSETS OR ANY OTHER MATTERS CONTAINED IN CONFIDENTIAL INFORMATION OR ANY
OTHER MATERIALS FURNISHED OR MADE AVAILABLE TO PURCHASER BY SELLER OR BY
SELLER'S AGENTS OR REPRESENTATIVES.  ANY AND ALL SUCH DATA, RECORDS, REPORTS,
PROJECTIONS, INFORMATION AND OTHER MATERIALS FURNISHED BY SELLER OR BY SELLER'S
AGENTS OR REPRESENTATIVES OR OTHERWISE MADE AVAILABLE TO PURCHASER OR


                                          11

<PAGE>


PURCHASER'S REPRESENTATIVES ARE PROVIDED TO OR FOR THE BENEFIT OF PURCHASER AS A
CONVENIENCE, AND SHALL NOT CREATE OR GIVE RISE TO ANY LIABILITY OF OR AGAINST
SELLER OR SELLER'S AGENTS OR REPRESENTATIVES.  ANY RELIANCE ON OR USE OF THE
SAME SHALL BE AT PURCHASER'S SOLE RISK.  THE ASSIGNMENTS AND BILLS OF SALE OR
OTHER CONVEYANCES TO BE DELIVERED BY SELLER AT CLOSING SHALL EXPRESSLY SET FORTH
THE LIMITATIONS AND DISCLAIMERS OF REPRESENTATIONS AND WARRANTIES CONTAINED IN
THIS PARAGRAPH.

    Seller covenants and agrees that from and after the execution of this
Agreement and until the Closing Date:

    4.23 MAINTENANCE OF ASSETS.  Seller will not sell, transfer, assign, convey
or otherwise dispose of any of the Assets subject to Seller's direct control,
other than (a)  oil, gas and other hydrocarbons produced, saved and sold in the
ordinary course of business, (b) personal property and equipment which is
replaced with property and equipment of comparable or better value and utility
in the ordinary and routine maintenance and operation of the Subject Properties,
and (c) as required in connection with any exercise of preferential rights or as
otherwise required to satisfy obligations to third parties under contracts
presently existing.

    4.24 NO ENCUMBRANCES.  Seller will not create any lien, security interest
or encumbrance on the Sale Interest, the oil or gas attributable to the Assets,
or the proceeds thereof, other than Permitted Encumbrances.

    4.25 OPERATIONS.  Seller will, subject to the rights of affected parties
under applicable agreements:

         (a)  cause the Subject Properties to be developed, maintained and
              operated in compliance with applicable laws, ordinances, rules,
              regulations and orders and in a prudent, good and workmanlike
              manner, maintain all permits, certificates, licenses,
              authorizations and insurance now in force with respect to the
              Subject Properties, and pay or cause to be paid all costs and
              expenses in connection therewith;

         (b)  not participate in the drilling of any new well on the Subject
              Properties or fail to participate in operations on the Subject
              Properties proposed by other parties, without the advance written
              consent of Purchaser, which consent (which may not be
              unreasonably withheld) or non-consent must be given by Purchaser
              within three (3) days of the notice from Seller;

         (c)  not take any action or fail to take any action which is
              reasonably expected to result in any termination of the leases
              forming a part of the Subject Properties;

         (d)  perform and comply with all of its obligations under agreements
              relating to or affecting the Subject Properties;

         (e)  carry on its business with respect to the Subject Properties in
              substantially the same manner as it has heretofore, not
              introducing any new method of management, operation or accounting
              with respect to the Subject Properties except as may be required
              by applicable statutes, rules or regulations or by applicable
              presently existing contractual obligations;


                                          12

<PAGE>


         (f)  not enter into or assume any contract, agreement or commitment
              which is not in the ordinary course of business as heretofore
              conducted or which involves payments, receipts or potential
              liabilities with respect to the Subject Properties of more than
              $25,000, excluding emergency expenditures; and

         (g)  not resign or otherwise voluntarily relinquish its rights as
              operator of any Subject Property for which it serves as operator
              on the date hereof.

         (h)  not grant any preferential right to purchase or similar right or
              agree to require the consent of any party to the transfer and
              assignment of the Assets to Purchaser, subject to existing
              contractual obligations;

         (i)  not enter into any gas sales contract or crude oil sales or
              supply contract with respect to the Subject Properties which is
              not terminable without penalty upon notice of  thirty (30) days
              or less;

         (j)  not enter into any transaction the effect of which, considered as
              a whole, would be to cause Seller's ownership interest in any of
              the Subject Properties to be altered from its ownership interest
              as of the date hereof;

         (k)  not enter into any settlement of or relinquish any outstanding
              receivables which are a part of the Assets (including, without
              limitations, the right to receive any retroactive price
              adjustments, take-or-pay monies, FERC mandated refunds,
              accounting adjustments, tax adjustments, and Minerals Management
              Service refunds);

         (l)  if any approval or consent by any federal, state or local
              governmental authority is required to vest Acceptable Title to
              any of the Sale Interest in Purchaser at Closing, exercise its
              best efforts, as reasonably requested in writing by Purchaser, to
              obtain all such required approvals or consents at Purchaser's
              expense;

         (m)  through Closing, give prompt written notice to Purchaser of any
              notice of default (or written threat of default, whether disputed
              or denied) received or given by Seller under any instrument or
              agreement affecting the Subject Properties to which Seller is a
              party or by which it or any of the Subject Properties is bound;
              and

         (n)  to the extent it can do so without violating any third party
              agreement and subject to the rights of third parties, exercise
              its best efforts to provide (as soon as practicable) Purchaser
              with a copy of each authority for expenditure and contract
              affecting the Subject Properties entered into after the date
              hereof; PROVIDED, however, that the provision of such matters to
              Purchaser is for informational purposes only and that Purchaser
              shall have no right to comment upon or object to any such matter
              that is otherwise not in violation of this Agreement.


                                          13

<PAGE>


          ARTICLE 5.  REPRESENTATIONS, WARRANTIES AND COVENANTS OF PURCHASER

    Purchaser represents and warrants to and covenants with Seller that
(PROVIDED, that each of CPC and CELLC, respectively, makes such representations,
warranties and covenants solely with respect to itself and not as to the other):

    5.1  EXISTENCE.  CELLC is a limited liability company duly organized,
validly existing and in good standing under the laws of the State of Texas.  CPC
is a corporation duly organized, validly existing and in good standing under the
laws of the State of Texas.

    5.2  POWER.  Purchaser has the requisite power and authority to enter into
and perform this Agreement and the transactions contemplated hereby.  The
execution, delivery and performance of this Agreement by Purchaser, and the
transactions contemplated hereby, will not (a) violate any provision of any
Purchaser's certificate or articles of incorporation or organization, as the
case may be, bylaws, regulations or other governing documents; (b) to the best
knowledge and belief of Purchaser, conflict with, result in a breach of,
constitute a default (or an event that with the lapse of time or notice, or both
would constitute a default) under any agreement or instrument to which Purchaser
is a party or by which Purchaser is bound, (c) to the best knowledge and belief
of Purchaser, violate any judgment, order, ruling, or decree applicable to
Purchaser and entered or delivered in a proceeding in which Purchaser was or is
a named party; or (d) to the best knowledge and belief of Purchaser, violate any
applicable law, rule or regulation.

    5.3  AUTHORIZATION.  The execution, delivery and performance of this
Agreement and the transactions contemplated hereby have been duly and validly
authorized by all requisite action on the part of Purchaser.  This Agreement has
been duly executed and delivered on behalf of Purchaser, and at the Closing all
documents and instruments required hereunder to be executed and delivered by
Purchaser shall have been duly executed and delivered.  This Agreement and such
documents and  instruments shall constitute legal, valid and binding obligations
of Purchaser enforceable in accordance with their terms, subject, however, to
the effect of bankruptcy, insolvency, reorganization, moratorium and similar
laws from time to time in effect relating to the rights and remedies of
creditors, as well as to general  principles of equity (regardless of whether
such enforceability is considered in a proceeding in equity or at law).

    5.4  BROKERS.  Purchaser has not incurred any obligation or liability,
contingent or otherwise, for brokers' or finders' fees in respect of the matters
provided for in this Agreement which will be the responsibility of Seller, and
any such obligation or liability that might exist shall be the sole obligation
of Purchaser.

    5.5  INVESTMENT INTENT.  Purchaser is acquiring the Assets for Purchaser's
own account for investment, and not with a view to, or for resale in connection
with, any distribution thereof within the meaning of the Securities Act of 1933,
and shall not resell any or all of the Assets except in compliance with all
applicable securities laws.

    5.6  ADDITIONAL INTERESTS.  If offered in writing to Purchaser by PPDLP,
Purchaser shall have the option to purchase, upon essentially the same terms and
conditions as contained herein, all additional right, title and interest, if
any, in and to the Assets acquired after the Effective Time by PPDLP, and, if
such option is exercised, the consideration paid therefor shall be the purchase
price paid by PPDLP.  Notwithstanding the immediately preceding sentence,
Purchaser shall purchase at Closing all interests in any of the Assets (which
are purchased by Purchaser) and described on Appendix I attached hereto offered
by the owners thereof for the purchase price described on Appendix I (which
amount has not been included in the Purchase Price), whether or not such
interests are acquired by


                                          14

<PAGE>


PPDLP prior to Closing, unless such interests are subject to Defects
specifically included in any Notice of Defects delivered hereunder, in which
case, at Seller's sole option, (i) such affected interest shall be excluded from
the Assets and the Purchase Price shall be reduced by the purchase price
allocated thereto on Appendix I, or (ii) the Purchase Price shall be reduced by
the purchase price allocated thereto on Appendix I and such interest shall be
conveyed to Purchaser at Closing as a part of the Assets. All such interests
acquired by Purchaser shall be deemed to be a part of the Sale Interest for all
purposes.


                      ARTICLE 6.  SELLER'S CONDITIONS OF CLOSING

    Seller's obligation to consummate the transactions provided for herein is
subject only to the satisfaction or waiver by Seller on or before the Closing
Date of the following conditions:

    6.1  REPRESENTATIONS.  The representations and warranties of Purchaser
contained in Article 5 shall be true and correct in all material respects on the
Closing Date as though made on and as of that date.

    6.2  PERFORMANCE.  Purchaser shall have performed in all material respects
the obligations, covenants and agreements hereunder to be performed by it at or
prior to the Closing.

    6.3  OFFICER'S CERTIFICATE.  Each Purchaser shall have delivered to Seller
a certificate of an executive officer dated the Closing Date, certifying on
behalf of such Purchaser that the conditions set forth in Sections 6.1 and 6.2
have been fulfilled.

    6.4  PENDING MATTERS.  No suit, action or other proceeding by a third party
or a governmental authority shall be pending or threatened which seeks
substantial damages from Seller in connection with, or seeks to restrain, enjoin
or otherwise prohibit, the consummation of the transactions contemplated by this
Agreement.

    6.5  HSR ACT.  The waiting period required by the HSR Act (as defined in
Section 13.20 below) shall have expired or been terminated.

                    ARTICLE 7.  PURCHASER'S CONDITIONS OF CLOSING

    Purchaser's obligation to consummate the transactions provided for herein
is subject only to the satisfaction or waiver by Purchaser on or before the
Closing Date of the following conditions:

    7.1  REPRESENTATIONS.  The representations and warranties of Seller
contained in Article 4 shall be true and correct in all material respects on the
Closing Date as though made on and as of that date.

    7.2  PERFORMANCE.  Seller shall have performed in all material respects the
obligations, covenants and agreements hereunder to be performed by it at or
prior to the Closing.

    7.3  OFFICER'S CERTIFICATE.  Seller shall have delivered to Purchaser
certificates of  executive officers of Seller's respective general partners,
dated the Closing Date, certifying on behalf of such Seller that the conditions
set forth in Sections 7.1 and  7.2 have been fulfilled.

    7.4  PENDING MATTERS.  No suit, action or other proceeding by a third party
or a governmental authority shall be pending or threatened which seeks
substantial damages from Purchaser in connection


                                          15

<PAGE>


with or, seeks to restrain, enjoin or otherwise prohibit, the consummation of
the transactions contemplated by this Agreement.

    7.5  HSR ACT.  The waiting period required by the HSR Act (as defined in
Section 13.20 below) shall have expired or been terminated.

    7.6  PIPELINE.  Purchaser's obligation to consummate the transaction
provided for herein with respect to the Pipeline shall be subject to Purchaser
having obtained, prior to or at Closing, every operating right (including
rights-of-way, easements and contracts), license, permit or federal, state or
local governmental approval (including without limitation, those required of any
federal, state or local governmental authority which are not assignable by
Seller or must be issued to Purchaser in its own name) and which is necessary in
order for Purchaser to acquire, own, possess and operate the Pipeline and to
conduct the business of the Pipeline as a gas transportation system, failing in
which (unless waived by Purchaser) the Purchase Price shall be reduced at
Closing by the Agreed Value of  the Pipeline, which Seller and Purchaser agree
for all purposes hereunder is $3,500,000.


                                 ARTICLE 8.  CLOSING

    8.1  TIME AND PLACE OF CLOSING.  If the conditions to Closing have been
satisfied or expressly waived by the party entitled to the benefits thereof, the
consummation of the transactions contemplated hereby ("CLOSING") shall take
place at Seller's offices in Midland, Texas, on May 31, 1996, at 9:00 a.m, or at
such other place and time or in such other manner agreed upon by Seller and
Purchaser ("CLOSING DATE"); PROVIDED, that Seller shall have the right to extend
Closing for up to thirty (30) days to respond to any Notice of Defects provided
by Purchaser and that any extension by Seller shall not serve to provide
Purchaser rights not otherwise expressly provided herein, nor to extend any
rights of Purchaser contained herein, including, without limitation, those
contained in Section 3.5.

    8.2  CLOSING OBLIGATIONS.  At the Closing,

    (a)  Seller shall execute, acknowledge and deliver to Purchaser (or its
         designee pursuant to Section 13.5) conveyance documents in mutually
         acceptable form and substance consistent herewith, by which the Assets
         shall be conveyed as provided hereby;

    (b)  Seller and Purchaser shall execute, acknowledge and deliver transfer
         orders or letters in lieu thereof directing all purchasers of
         production to make payment to Purchaser of proceeds attributable to
         the Sale Interest;

    (c)  Purchaser shall deliver the Adjusted Purchase Price as provided in
         Article 2;

    (d)  Purchaser and Seller shall execute and deliver a settlement statement
         (the "PRELIMINARY SETTLEMENT STATEMENT") prepared by Seller and
         setting forth the Purchase Price and all adjustments thereto agreed
         upon by the parties, using the best information available, subject to
         Section 13.18; and

    (e)  Purchaser and Seller shall execute such other instruments and take
         such other action as may be necessary to carry out their respective
         obligations under this Agreement.


                                          16

<PAGE>


                         ARTICLE 9.  POST-CLOSING OBLIGATIONS

    9.1  RECEIPTS AND CREDITS; SUSPENSE FUNDS.  Subject to the terms hereof,
all monies, refunds, proceeds, receipts, credits, receivables, accounts and
income attributable to the purchased Assets (a) for all periods of time from and
after the Effective Time shall be the sole property and entitlement of the
Purchaser, and, to the extent received by Seller, Seller shall fully disclose
and account therefor to Purchaser promptly, and (b) for all periods of time
prior to the Effective Time shall be the sole property and entitlement of Seller
to the extent received by Purchaser or Seller prior to the Final Accounting Date
or allocated to Seller in the Final Accounting, and if received by Purchaser,
Purchaser shall fully disclose and account therefore to Seller promptly.
Purchaser shall pay Seller for Seller's share of hydrocarbons attributable to
the purchased Assets in storage above the pipeline connection or in transit on
the Effective Time at the purchaser's then posted field price for hydrocarbons
of like grade and gravity in the relevant field, net of all applicable taxes.
Seller and Purchaser recognize that as of the Effective Time there may be over
or under imbalances with respect to gas production, gathering, transportation or
processing attributable to the Subject Properties ("IMBALANCES") and hereby
agree that (i) Imbalances shall not be included in any Identified Claims
asserted hereunder (except as provided in the proviso following the next
clause), and (ii) the Subject Properties will be conveyed specifically subject
to Imbalances which exist as of the Effective Time, with Purchaser, as of
Closing, bearing and assuming all obligations with respect to any overproduction
account or liability and receiving the benefit of and being credited with any
underproduction account or credit; PROVIDED, however, that with respect to
Subject Properties that are subject to gas balancing agreements, Purchaser (x)
may include any net overproduced Imbalance as an Identified Claim hereunder, or
(y) at Closing shall pay Seller an amount determined by multiplying the net
underproduced Imbalance by $1.00/MCF.  At Closing, Seller shall deliver to
Purchaser all amounts in Seller's possession due third party owners of interests
in the Subject Properties, and Purchaser agrees that it shall be solely
responsible for the disposition of such funds, the payment thereof to the
rightful owners and the payment, if any, of royalty thereon (the "SUSPENSE
FUNDS").

    9.2  COSTS AND LIABILITIES; INDEMNITY.

         (a)  As used in this Agreement, "CLAIMS" shall include costs,
              expenses, obligations, claims, demands, causes of action,
              liabilities, damages, fines, penalties and judgments of any kind
              or character, whether matured or unmatured, absolute or
              contingent, accrued or unaccrued, liquidated or unliquidated,
              known or unknown, and all costs and fees (including, without
              limitation, interest, attorneys' fees, costs of experts, court
              costs and costs of investigation) incurred in connection
              therewith, including, but not limited to claims arising from or
              directly or indirectly related to royalty, operating, suspense
              and capital obligations attributable to the purchased Assets.  As
              used in this Section 9.2, "ASSETS" shall include the Suspense
              Funds.

         (b)  Notwithstanding anything in this Agreement to the contrary, it is
              the express intent and agreement of Seller and Purchaser that, if
              Closing occurs, Purchaser shall accept the purchased Assets in
              their "AS IS, WHERE IS" condition, subject to any and all
              defects, deficiencies, irregularities and claims related or
              attributable in any manner  thereto, including, without
              limitation, Title Defects, Contract Defects, Environmental
              Defects, Identified Claims or any other matter affecting in any
              respect the title or physical condition of,  or the right to own,
              use, operate, develop or enjoy, the purchased Assets, whether
              known or unknown, liquidated or unliquidated, fixed or
              contingent, direct or indirect.


                                          17

<PAGE>


         (c)  At Closing and without further action or documentation, Purchaser
              (1) shall assume, be responsible for and comply with all duties
              and obligations, express or implied, arising at any time with
              respect to the purchased Assets, including, without limitation
              (i) those arising under or by virtue of any lease, contract,
              agreement, document, permit, law, statute, rule, regulation or
              order of any governmental authority or court (specifically
              including, without limitation, any governmental request or other
              requirement to plug, re-plug or abandon any well of whatsoever
              type, status or classification, or take any clean-up, remedial or
              other action with respect to the purchased Assets), (ii)
              preferential rights to purchase and (iii) third party consents;
              (2) shall assume, be responsible for and pay all claims affecting
              or arising, directly or indirectly, at any time in connection
              with the purchased Assets, including, without limitation, claims
              for personal or property injury or damage, environmental cleanup,
              remediation, or compliance, or for any other relief, arising
              directly or indirectly from or incident to, the use, occupation,
              operation, maintenance or abandonment of or production from the
              purchased Assets, or condition of the purchased Assets, whether
              latent or patent, including, without limitation, contamination of
              property or premises with Naturally Occurring Radioactive
              Materials ("NORM"), and whether or not arising solely from or
              contributed to by the negligence in any form, whether active or
              passive, or of any kind or nature, of Seller or its predecessors
              in title or their respective agents, employees or contractors;
              and (3) shall defend, indemnify and hold Seller harmless from any
              and all claims arising, asserted or due at any time in connection
              with the foregoing.

         (d)  From and after Closing, any claim for indemnity hereunder shall
              be made by written notice, together with a written description of
              any claims asserted stating the nature and basis of such claim
              and, if ascertainable, the amount thereof.  Purchaser shall have
              a period of twenty (20) days after receipt of such notice within
              which to respond thereto or, in the case of a claim which
              requires a shorter time for response, then within such shorter
              period as specified by Seller in such notice (the "NOTICE
              PERIOD").  If Purchaser denies liability hereunder or fails to
              provide the defense for any claim, Seller may defend or
              compromise the claim as it deems appropriate without prejudice to
              any of Seller's rights hereunder, with no right of Purchaser to
              approve or disapprove any actions taken in connection therewith
              by Seller.  If Purchaser accepts liability and responsibility for
              the defense of any claim, it shall so notify Seller as soon as is
              practicable prior to the expiration of the Notice Period and
              undertake the defense or compromise of such claim with counsel
              selected by Purchaser and reasonably acceptable to Seller.  If
              Purchaser undertakes the defense or compromise of such claim,
              Seller shall be entitled, at its own expense, to participate in
              such defense.  No compromise or settlement of any claim shall be
              made without reasonable notice to Seller, and without the prior
              written approval of Seller, which approval shall not be
              unreasonably withheld or delayed, unless such compromise or
              settlement includes a general and complete release of Seller, its
              Affiliates and their respective Representatives in respect of the
              matter, with prejudice, and with no express or written admission
              of liability on the part of Seller, its Affiliates and their
              respective Representatives, and no constraints on the future
              conduct of its or their respective businesses.


                                          18

<PAGE>


         (e)  Seller shall have the right at all times to participate, at its
              sole cost, in the preparation for any hearing or trial related to
              the indemnities set forth in this Agreement, as well as the right
              to appear on its own behalf or to retain separate counsel to
              represent it at any such hearing or trial.

         (f)  THE INDEMNITIES PROVIDED IN THIS AGREEMENT SHALL EXTEND TO SELLER
              AND ITS AFFILIATES AND ANY PERSON WHO AT ANY TIME HAS SERVED OR
              IS SERVING AS A DIRECTOR, OFFICER, EMPLOYEE, CONSULTANT, INVITEE
              OR AGENT THEREOF (EACH A "REPRESENTATIVE"), AND EACH OF THEIR
              RESPECTIVE HEIRS, EXECUTORS, SUCCESSORS AND ASSIGNS, AND SHALL
              APPLY TO ALL CLAIMS SUBJECT TO INDEMNITY HEREUNDER, INCLUDING
              THOSE BASED ON NEGLIGENCE OF ANY NATURE, INCLUDING SOLE
              NEGLIGENCE, SIMPLE NEGLIGENCE, CONCURRENT NEGLIGENCE, ACTIVE
              NEGLIGENCE, PASSIVE NEGLIGENCE, STRICT LIABILITY OR FAULT OF
              SELLER (OR ANY OTHER INDEMNIFIED PARTY) OR ANY OTHER THEORY OF
              LIABILITY OR FAULT, WHETHER OF LAW (WHETHER COMMON OR STATUTORY)
              OR IN EQUITY; PROVIDED, HOWEVER, PURCHASER SHALL NOT BE LIABLE
              FOR OR INDEMNIFY SELLER FOR ANY CLAIM ASSERTED BY PURCHASER AND
              ARISING FROM A BREACH BY SELLER OF THIS AGREEMENT.  THE
              INDEMNIFICATION PROVISIONS OF THIS SECTION 9.2 SHALL BE IN
              ADDITION TO ANY OTHER INDEMNITY PROVISIONS CONTAINED IN THIS
              AGREEMENT, AND IT IS EXPRESSLY UNDERSTOOD AND AGREED THAT THE
              TERMS OF THIS SECTION 9.2 SHALL CONTROL OVER ANY CONFLICTING OR
              CONTRADICTING TERMS OR PROVISIONS CONTAINED IN THIS AGREEMENT,
              AND SHALL SURVIVE CLOSING.

    9.3  FURTHER ASSURANCES.  After Closing, Seller and Purchaser agree to take
such further actions and to execute, acknowledge and deliver all such further
documents that are necessary or useful in carrying out the purposes of this
Agreement or of any document delivered pursuant hereto.

    9.4  DELIVERY OF RECORDS.  As soon as reasonably possible but no later than
thirty (30) days after the Closing Date, Seller shall deliver originals (or
copies where originals are not available) of the Records to Purchaser; PROVIDED,
that Seller (i) shall exercise its best efforts to provide Purchaser at Closing
or as soon thereafter as is practicable with all Records necessary to assume and
conduct operations of the Assets, and (ii) shall have the right to retain, as
its own, original Records that pertain to the Excluded Assets and copies of all
other Records.

    9.5  ACCESS TO DATA.  Subject to the rights of third parties and to the
extent attributable to the purchased Subject Properties, Seller shall provide
Purchaser reasonable access at their place of storage to all seismic, geologic
and geophysical records and data not obtained from SFER, SFEOP, SFERP-A or any
of their respective Affiliates and in Seller's possession as of the Effective
Time.  Subject to the rights of third parties and Seller's proprietary rights,
Seller shall provide Purchaser with reasonable access to Seller's books and
records after Closing as necessary for Purchaser to prepare its financial
statements.

                               ARTICLE 10.  TERMINATION

    10.1 RIGHT OF TERMINATION.  This Agreement and the transactions
contemplated hereby may be terminated at any time at or prior to the Closing:


                                          19

<PAGE>


         (a)  by Seller if Closing does not occur on or before July 1, 1996;

         (b)  by mutual consent of the parties;

         (c)  by Purchaser or Seller in accordance with Section 3.6;

         (d)  by Purchaser by notice delivered to Seller on or before Closing
              if all conditions described in Article 7 shall not have been met
              and such noncompliance shall not have been caused or waived by
              the actions or inactions of Purchaser;

         (e)  by Seller by notice delivered to Purchaser on or before Closing
              if (1) all conditions described in Article 6 shall not have been
              met and such noncompliance shall not have been caused or waived
              by the actions or inactions of Seller, or (2) Purchaser has not
              made the filings and requests required of it by the first
              sentence of Section 13.20 prior to April 20, 1996; or

         (f)  by Seller if the Second Installment is not made in accordance
              herewith.

    10.2 EFFECT OF TERMINATION.  If this Agreement is terminated pursuant to
Section 10.1, this Agreement shall become void and of no further force or effect
(except for the provisions of Sections 4.4, 5.4,  13.1 through 13.11 and 13.14
through 13.17, each of which shall survive such termination and continue in full
force and effect); PROVIDED, however, (i) that if either party is in material
default of its obligations under this Agreement at the time this Agreement is so
terminated, such defaulting party shall continue to be liable to the other party
for damages and other remedies available at law or in equity (including, without
limitation, for specific performance) in respect of such default and such
liability shall not be affected by such termination; and (ii) if this Agreement
is so terminated by Purchaser, in the absence of a default hereunder by
Purchaser, the Deposit shall be returned to Purchaser, or if so terminated by
Seller, as the result of a default hereunder by Purchaser, the Seller may, in
its sole discretion, elect to retain the Deposit as liquidated damages (it being
agreed by the parties that damages in said event would be extremely difficult to
determine, and that the Deposit represents a fair and reasonable estimate of
such damages under the circumstances, and does not constitute a penalty).
Notwithstanding anything to the contrary contained in this Agreement, upon any
termination of this Agreement pursuant to Section 10.1 by Seller, in the absence
of a material default hereunder by Seller, Seller shall be free immediately to
enjoy all rights of ownership of the Assets and may sell, transfer, encumber or
otherwise dispose of the Assets to any party without any restriction under this
Agreement and without any impairment of its rights hereunder to recover damages
from Purchaser arising from any default hereunder by Purchaser; PROVIDED, that
Seller's right to seek specific performance of Purchaser's obligations hereunder
shall be waived upon any such disposition of the Assets and that its right to
seek or recover any other damages shall be waived upon its election to retain
the Deposit, if, and only if the First Installment and Second Installment have
been paid in accordance herewith.


                                  ARTICLE 11.  TAXES

    11.1 APPORTIONMENT OF AD VALOREM AND PROPERTY TAXES.  All ad valorem taxes,
real property taxes, personal property taxes, and similar obligations concerning
the Assets with respect to the tax period in which the Effective Time occurs
("PROPERTY TAXES") shall be apportioned as of the Effective Time between Seller
and Purchaser.  Seller shall file or cause to be filed all required reports and
returns incident to the Property Taxes and shall pay or cause to be paid to the
taxing authorities all Property Taxes relating to the tax period in which the
Effective Time occurs.  Purchaser shall pay to Seller


                                          20

<PAGE>


Purchaser's pro rata portion of Property Taxes within thirty (30) days after
receipt of Seller's invoice therefor.

    11.2 SALES TAXES.  The Purchase Price excludes any sales taxes or other
taxes required to be paid in connection with the sale of property pursuant to
this Agreement.  Purchaser shall be liable for all sales, use and other taxes,
conveyance, transfer and recording fees and real estate transfer stamps or taxes
that may be imposed on any transfer of property pursuant to this Agreement.
These taxes shall be collected and remitted under applicable law.  Purchaser
shall indemnify and hold Seller harmless with respect to the payment of any of
these taxes including any interest or penalties assessed thereon.

    11.3 OTHER TAXES.  All taxes (other than income taxes) which are imposed on
or with respect to the production of oil, natural gas or other hydrocarbons or
minerals or the receipt of proceeds therefrom (including but not limited to
severance, production, and excise taxes) shall be apportioned between the
parties based upon  the respective shares of production taken by the parties.
From and after Closing, Purchaser shall be responsible for paying or withholding
or causing to be paid or withheld all such taxes and for filing all statements,
returns, and documents incident thereto.

    11.4 COOPERATION.  Each party to this Agreement shall provide the other
party with reasonable access to all relevant documents, data and other
information which may be required by the other party for the purpose of
preparing tax returns and responding to any audit by any taxing jurisdiction.
Each party to this Agreement shall cooperate with all reasonable requests of the
other party made in connection with contesting the imposition of taxes.
Notwithstanding anything to the contrary in this Agreement, neither party to
this Agreement shall be required at any time to disclose to the other party any
tax return or other confidential tax information.

                     ARTICLE 12.  PHYSICAL CONDITION OF THE ASSETS

    12.1 PRIOR USE OF ASSETS.  THE ASSETS HAVE BEEN USED FOR OIL AND GAS
DRILLING AND PRODUCING OPERATIONS AND RELATED OIL FIELD OPERATIONS.  PHYSICAL
CHANGES IN THE LAND MAY HAVE OCCURRED AS A RESULT OF SUCH USES.  THE ASSETS ALSO
MAY INCLUDE BURIED PIPELINES AND OTHER EQUIPMENT,  WHETHER OR NOT OF A SIMILAR
NATURE, THE LOCATIONS OF WHICH MAY NOT NOW BE KNOWN BY SELLER OR READILY
APPARENT BY A PHYSICAL INSPECTION OF THE PROPERTY.  PURCHASER UNDERSTANDS THAT
SELLER DOES NOT HAVE THE REQUISITE INFORMATION WITH WHICH TO DETERMINE THE EXACT
NATURE OR CONDITION OF THE ASSETS OR THE AFFECT ANY SUCH USE HAS HAD ON THE
PHYSICAL CONDITION OF THE LANDS BURDENED BY THE ASSETS.

              12.2 ASSUMPTION OF ASSETS IN PRESENT CONDITION.  PURCHASER
ACKNOWLEDGES THAT (i) THE CONSUMMATION OF THIS AGREEMENT BY PURCHASER SHALL BE
ON THE BASIS OF ITS OWN INVESTIGATION OF THE PHYSICAL CONDITION OF THE ASSETS,
INCLUDING, WITHOUT LIMITATIONS, SUBSURFACE CONDITION; (ii) THE ASSETS HAVE BEEN
USED IN THE MANNER AND FOR THE PURPOSES SET FORTH ABOVE AND THAT PHYSICAL
CHANGES TO THE ASSETS AND THE LANDS BURDENED THEREBY MAY HAVE OCCURRED AS A
RESULT OF SUCH USE; AND (iii) NORM AND MAN-MADE MATERIAL FIBERS ("MMMF") MAY BE
PRESENT AT SOME LOCATIONS.  PURCHASER ACKNOWLEDGES THAT NORM IS A NATURAL
PHENOMENON ASSOCIATED WITH MANY OIL FIELDS IN THE UNITED STATES AND THROUGHOUT
THE WORLD. PURCHASER SHALL MAKE ITS OWN DETERMINATION OF THIS PHENOMENON AND
OTHER CONDITIONS.  SELLER DISCLAIMS ANY LIABILITY ARISING OUT OF OR IN
CONNECTION WITH ANY PRESENCE OF NORM OR MMMF ON OR AFFECTING THE ASSETS.  IN
ACCORDANCE WITH SECTION 9.2 AND AT CLOSING, PURCHASER SHALL ASSUME THE RISK THAT
THE PURCHASED ASSETS


                                          21

<PAGE>


MAY CONTAIN WASTES OR CONTAMINANTS AND ADVERSE PHYSICAL CONDITIONS, INCLUDING
THE PRESENCE OF PIPELINES, EQUIPMENT AND OTHER ITEMS OF PERSONAL PROPERTY, AND
WASTES OR CONTAMINANTS WHICH MAY NOT HAVE BEEN REVEALED BY PURCHASER'S
INVESTIGATION.  IN ACCORDANCE WITH SECTION 9.2 AND AT CLOSING, ALL
RESPONSIBILITY AND LIABILITY RELATED TO DISPOSALS, SPILLS, WASTES, OR
CONTAMINATION, OR OTHER ADVERSE PHYSICAL CONDITIONS ON, BELOW, OR RELATED TO OR
AFFECTING THE PURCHASED ASSETS SHALL BE ASSUMED BY PURCHASER AND PURCHASER
SHALL, NOTWITHSTANDING WHEN THE BASIS FOR ANY CLAIM, ACTION, SUIT, JUDGMENT
(INCLUDING, WITHOUT LIMITATION, THOSE FOR DEATH, PERSONAL INJURY OR PROPERTY
DAMAGE) SHALL HAVE OCCURRED, INDEMNIFY, DEFEND AND HOLD SELLER HARMLESS
THEREFROM PURSUANT TO SECTION 9.2.

              12.3 CASUALTY LOSS.  In the event of any material damage by fire
or other casualty to any of the Assets prior to the Closing ("CASUALTY LOSS"),
this Agreement shall remain in full force and effect, and as to each affected
Asset, Seller shall at its election either collect (and when collected pay over
to Purchaser) or assign to Purchaser any and all insurance claims related to
such damage, and Purchaser shall take title to the affected Asset without
reduction in the Purchase Price.

                             ARTICLE  13.  MISCELLANEOUS

              13.1  GOVERNING LAW.  This Agreement and all instruments executed
in accordance herewith shall be governed by and interpreted in accordance with
the laws of the State of Texas, without regard to conflict of law rules that
would direct  application of the laws of another jurisdiction, except to the
extent that it is mandatory that the law of the jurisdiction wherein the Assets
are located shall apply.  In the event of any litigation or other proceeding in
connection with this Agreement, the venue for any such proceeding shall be in a
court of competent jurisdiction located in Midland County, Texas, and the
prevailing party shall be entitled to recover its reasonable attorney's fees and
costs incurred therein from the other party, in addition to any damages awarded.


              13.2  ENTIRE AGREEMENT.  This Agreement, all agreements and
instruments executed in connection herewith and the Confidentiality Agreement
dated January 22, 1996, between CPC, CELLC and Parker & Parsley Petroleum
Company (the "CONFIDENTIALITY AGREEMENT") constitute the entire agreement
between the parties and supersede all prior agreements, understandings,
negotiations and discussions, whether oral or written, of the parties.  No
supplement, amendment, alteration, modification, waiver or termination of this
Agreement shall be binding unless executed in writing by the parties hereto.

              13.3  WAIVER.  No waiver of any of the provisions of this
Agreement shall be deemed or shall constitute a waiver of any other provisions
hereof (whether or not similar), nor shall such waiver constitute a continuing
waiver unless otherwise expressly provided.

              13.4  CAPTIONS.  The captions in this Agreement are for
convenience only and shall not be considered a part of or affect the
construction or interpretation of any provision of this Agreement.

              13.5  ASSIGNABILITY.  Except pursuant to a like kind exchange
pursuant to Section 2.3, neither party hereto shall assign (whether before, at
or after Closing) this Agreement or any of its rights or obligations hereunder
without the prior written consent of the other party, which may be withheld for
any or no reason.  Any assignment made without such consent shall be void.
Except as otherwise provided herein, this Agreement shall be binding upon and
inure to the benefit of the parties hereto and their respective permitted
successors and assigns; PROVIDED, that Seller agrees that at Purchaser's written
request received on or before May 1, 1996, Seller will convey at Closing


                                          22

<PAGE>


the Assets to Purchaser and its Affiliates, including without limitation, to
Valley Gathering Company, a Texas corporation, in the proportions identified in
such written request; further PROVIDED, that for the purposes of this Agreement,
expressly including, without limitation, Article 9, all such Assets conveyed to
Valley Gathering Company or any other Affiliate of Purchaser shall be deemed to
be Assets purchased hereunder by Purchaser for all purposes.

              13.6  NOTICES.  Any notice provided or permitted to be given
under this Agreement shall be in writing, and may be served by personal delivery
or by registered or certified U.S. mail, addressed to the party to be notified,
postage prepaid, return receipt requested.  Notice deposited in the mail in the
manner hereinabove described shall be deemed to have been given and received on
the date of the delivery as shown on the return receipt.  Notice served in any
other manner (including by facsimile delivery) shall be deemed to have been
given and received only if and when actually received by the addressee.  For
purposes of notice, the addresses of the parties shall be as follows:

SELLER:

         Parker & Parsley Development L.P.
         Parker & Parsley Producing L.P.
         Attn:  Tim Leach and W.T. Howard
         303 W. Wall, Suite 101
         Midland, Texas  79701
         Telephone:     (915) 683-4768
         Fax:           (915) 571-5050

         with copy to:       David W. Copeland
                             303 W. Wall, Suite 101
                             Midland, Texas  79701
                             Telephone:     (915) 683-4768
                             Fax:           (915) 571-5815



PURCHASER:

         Costilla Energy, L.L.C.
         Attn: Cliff Hair
         511 West Texas
         Midland, Texas  79701
         Telephone:     (915) 683-3092
         Fax:           (915) 685-0841

         with copy to:       Michael J. Grella
                             511 West Texas
                             Midland, Texas  79701
                             Telephone:     (915) 683-3092
                             Fax:           (915) 685-0841

Each party shall have the right, upon giving three (3) days prior notice to the
other in the manner hereinabove provided, to change its address for purposes of
notice to any other appropriate street address.


                                          23

<PAGE>


              13.7  DTPA WAIVER.  TO THE EXTENT APPLICABLE TO THE ASSETS OR ANY
PORTION THEREOF, EACH PURCHASER HEREBY WAIVES THE PROVISIONS OF THE TEXAS
DECEPTIVE TRADE PRACTICES ACT, CHAPTER 17, SUBCHAPTER E, SECTIONS 17.41 THROUGH
17.63, INCLUSIVE (OTHER THAN SECTION 17.555, WHICH IS NOT WAIVED), TEX. BUS. &
COM. CODE.  IN ORDER TO  EVIDENCE ITS ABILITY TO GRANT SUCH WAIVER, PURCHASER
HEREBY REPRESENTS AND WARRANTS TO SELLER THAT IT (i) IS IN THE BUSINESS OF
SEEKING OR ACQUIRING, BY PURCHASE OR LEASE, GOODS OR SERVICES FOR COMMERCIAL OR
BUSINESS USE; (ii) HAS ASSETS OF $5,000,000 OR MORE ACCORDING TO ITS MOST RECENT
FINANCIAL STATEMENT PREPARED IN ACCORDANCE WITH GENERALLY ACCEPTED ACCOUNTING
PRINCIPLES; (iii) HAS KNOWLEDGE AND EXPERIENCE IN FINANCIAL, BUSINESS AND OIL
AND GAS MATTERS THAT ENABLE IT TO EVALUATE THE MERITS AND RISKS OF THE
TRANSACTIONS CONTEMPLATED HEREBY; (iv) IS NOT IN A SIGNIFICANTLY DISPARATE
BARGAINING POSITION; AND (v) THAT THIS WAIVER IS A MATERIAL AND INTEGRAL PART OF
THIS AGREEMENT AND THE CONSIDERATION THEREOF.

              13.8  EXPENSES. Each party shall be solely responsible for all
expenses incurred by it in connection with this transaction (including, without
limitation, fees and expenses of its own legal counsel and accountants).

              13.9  SEVERABILITY. If any term or other provision of this
Agreement is invalid, illegal or incapable of being enforced under any rule of
law, all other conditions and provisions of this Agreement shall nevertheless
remain in full force and effect so long as the economic or legal substance of
the transactions contemplated hereby is not affected in a materially adverse
manner with respect to either party.

              13.10  DAMAGES. The parties waive any rights to punitive and
incidental or consequential damages resulting from a breach of this Agreement.

              13.11  NO THIRD PARTY BENEFICIARY.  This Agreement is not
intended to create, nor shall it be construed to create, any rights in any third
party under doctrines concerning third party beneficiaries.

              13.12  SURVIVAL.  The representations and warranties of the
parties under this Agreement shall not survive, but shall terminate upon and be
extinguished by, Closing; PROVIDED, however, that (i) all representations,
waivers, covenants, agreements and indemnities contained entirely within
Sections 1.2, 3.1, 3.6, 3.7, 4.1 through 4.5 and 5.1 through 5.6, and Articles
9, 11, 12 or 13 of this Agreement shall survive the Closing, and (ii) Seller's
obligation with respect to Further Conveyances (as defined in Section 3.1 above)
shall expire on the first anniversary of the Closing Date with respect to
matters not asserted prior to such anniversary date with the specificity
required of Notice of Defects given hereunder; FURTHER PROVIDED, that,
notwithstanding anything herein to the contrary, Purchaser expressly agrees and
acknowledges that it shall have no remedy or recourse against Seller or its
Affiliates or any of their respective Representatives with respect to the
condition of the Assets or any representation or warranty made in connection
with this Agreement, except as expressly provided by Section 3.6.

              13.13  COUNTERPARTS.  This Agreement may be executed in one or
more counterparts, each of which shall be deemed an original, but all of which
together shall constitute one and the same instrument.

              13.14  CERTAIN DEFINITIONS.  As used in this Agreement, (a) the
term "AFFILIATE" means, as to any Person, each other Person that directly or
indirectly (through one or more


                                          24

<PAGE>


intermediaries or otherwise) controls, is controlled by, or is under common
control with, such Person; (b) the term "PERSON" means an individual,
corporation, partnership, association, joint stock company, trust or trustee
thereof, estate or executor thereof, unincorporated organization or joint
venture, court or other governmental unit or any agency or subdivision thereof,
or any other legally recognizable entity; and (c) the terms "TO [SELLER'S OR
PURCHASER'S, AS THE CASE MAY BE] KNOWLEDGE"  or "KNOWN TO"  and other terms of
similar import shall mean, with respect to the referenced party, only the then
existing actual non-privileged knowledge of any president or vice president of
such party or of such party's general or managing partner or agent, as the case
may be, and are not intended to imply that such party in fact has actual
knowledge of the subject matter to which such terms apply.

              13.15  CONSTRUCTION OF AMBIGUITY.  In the event of any ambiguity
in any of the terms or conditions of this Agreement, including any exhibits
hereto and whether or not placed of record, such ambiguity shall not be
construed for or against any party hereto on the basis that such party did or
did not author the same.

              13.16  WAIVER OF JURY TRIAL.  SELLER AND PURCHASER DO HEREBY
IRREVOCABLY WAIVE, TO THE FULLEST EXTENT PERMITTED BY LAW, ANY AND ALL RIGHT TO
A TRIAL BY JURY IN ANY ACTION, SUIT OR OTHER LEGAL PROCEEDING BASED UPON,
ARISING OUT OF OR RELATING TO THIS AGREEMENT OR THE TRANSACTIONS CONTEMPLATED
HEREBY.

              13.17  PUBLICITY.  Seller and Purchaser shall consult with each
other with regard to all publicity and other releases and disclosures to be made
prior to, at or after Closing concerning this Agreement and the transactions
contemplated hereby, which are not otherwise expressly permitted by the
Confidentiality Agreement, and, except as required by applicable law or the
applicable rules or regulations of any governmental body or stock exchange,
neither party shall make any disclosure or issue any publicity or other release
without the prior written consent of the other party, which consent shall not be
unreasonably withheld or delayed.

              13.18  ACCOUNTING.

              A.   Seller shall deliver to Purchaser on or before the fourth
                   business day prior to Closing the Preliminary Settlement
                   Statement setting forth any adjustments to the Purchase
                   Price provided for in or required by this Agreement, using
                   estimates where actual amounts are not known at the Closing.
                   The Preliminary Settlement Statement shall be prepared in
                   accordance with this Agreement and with standard industry
                   and accounting practices.  In connection with the
                   preparation of the Preliminary Settlement Statement, the
                   Purchase Price shall be (1) increased by (a) the costs and
                   expenses that are attributable to the Subject Properties for
                   the period from the Effective Time to the Closing Date that
                   are paid, incurred or assessed by Seller (including,
                   administrative overhead for wells operated by Seller and
                   attributable to Seller's interest in such wells), and (b)
                   other amounts due Seller and contemplated hereby, and (2)
                   reduced by (a) proceeds received by Seller for hydrocarbons
                   attributable to the Subject Properties  produced after the
                   Effective Time, and (b) other amounts due Purchaser and
                   contemplated hereby.

              B.   As soon as reasonably practicable after the Closing, but not
                   later than ninety (90) days thereafter Seller shall prepare,
                   in accordance with this Agreement and with standard industry
                   and accounting practices, and


                                          25

<PAGE>



                   deliver to Purchaser, a final accounting statement showing
                   the proration and calculation of credits and payment
                   obligations of Purchaser and Seller hereunder.  As soon as
                   reasonably practicable thereafter, Purchaser shall deliver
                   to Seller a written report containing any changes that
                   Purchaser  proposes to be made to such statement.  The
                   parties shall use their best efforts to reach agreement (the
                   "FINAL ACCOUNTING") on the final accounting statement on or
                   before the 120th day after the Closing Date (such date the
                   "FINAL ACCOUNTING DATE", whether or not Seller and Purchaser
                   have agreed on the Final Accounting).  Once the Final
                   Accounting has been agreed to by Purchaser and Seller, there
                   shall be no further adjustments to the Purchase Price.

              13.19  OPERATORSHIP.  Seller does not represent to Purchaser that
Purchaser will automatically succeed to the operatorship of any given Subject
Property as to which Seller is currently the operator.  Purchaser recognizes and
agrees that Purchaser will be required to comply with applicable operating
agreements, unit operating agreements or other similar contracts relating to any
elections or other selection procedures in order to succeed Seller as operator.

              13.20  HSR ACT.  The parties shall exercise their best efforts to
file (or will cause their ultimate parent entities to file) with the United
States Federal Trade Commission and the United States Department of Justice all
notifications and reports required for the transaction contemplated hereby under
the Hart-Scott-Rodino Antitrust Improvements Act of 1976 ("HSR ACT"), and shall
request early termination of the prescribed waiting period.  Both parties shall
use their best efforts to promptly supply any supplemental or additional
information which may be requested in connection therewith pursuant to the HSR
Act and shall comply in all material respects with the requirements of the HSR
Act.  Closing of the transaction contemplated hereby shall not occur unless and
until all necessary filings and notifications under the HSR Act have been made,
including the provision of any required additional information or documents, and
the waiting period referred to in such Act shall have expired or terminated.

              13.21  SELLER'S EMPLOYEES.  Purchaser will interview and evaluate
in accordance with its normal employment procedures those Persons (not to exceed
30) employed by Seller in connection with the Subject Properties and identified
by letter dated on or before fifteen days hereafter from Seller to Purchaser who
desire to be considered for employment by Purchaser, and will offer in writing
employment to those Persons for whom Purchaser in its sole discretion determines
a need.  If Purchaser fails to offer such employment to all of such Persons,
Purchaser shall not, as a result of such failure, otherwise be in default under
this Agreement, but shall be required to reimburse Seller for severance benefits
paid by Seller to each such Person not offered employment by Purchaser;
PROVIDED, that such reimbursement shall not exceed that amount determined by
multiplying each such employee's normal weekly wage by ten (10).  Persons
offered employment with Purchaser will be offered employment at their current
work location with compensation and benefits comparable to those provided to
Purchaser's current employees performing similar tasks, or, if none, with
compensation and benefits comparable to those provided by Seller.  Such offers
shall be made at least fifteen (15) days prior to Closing, but shall be
contingent upon the occurrence of Closing and such employment shall not commence
until Closing.  If any such Person employed by Purchaser is terminated by
Purchaser within six (6) months of Closing, Purchaser shall pay such Person a
severance benefit equal to the amount determined by multiplying each such
employee's normal weekly wage by ten (10).  Purchaser shall have no obligation
under this Section 13.21 with respect to Persons offered employment by Purchaser
pursuant to this Section 13.21 who decline such employment, except that the
foregoing


                                          26

<PAGE>


provisions shall apply to the extent that such Person accepts employment with
Purchaser or any of its Affiliates within twelve (12) months of Closing.

              13.22  OPINIONS OF COUNSEL.  Not later than March 18, 1996,
Purchaser and Seller shall deliver to the other the opinion of  its counsel,
reasonably acceptable to the receiving party, to the effect that (a) such party
is authorized and empowered to enter into and consummate and perform this
Agreement, (b) this Agreement will be binding upon and enforceable against such
party according to its terms, and (c) no further resolutions or approvals of
such party are necessary to authorize and empower such party to consummate this
Agreement and perform hereunder; such opinion to be in form and substance
reasonably acceptable to the receiving party.

                     [REMAINDER OF PAGE LEFT BLANK INTENTIONALLY]


                                          27

<PAGE>

                    EXECUTED as of the date first set forth above.

                                  SELLER:

                                PARKER & PARSLEY DEVELOPMENT L.P.,
                                 by Parker & Parsley Petroleum USA, Inc.,
                                    General Partner


                              By:    /s/ T. A. Leach
                                     -------------------------------------
                                     T. A. Leach, Executive Vice President

                                PARKER & PARSLEY PRODUCING L.P.,
                                 by Parker & Parsley, Inc., General Partner


                                By:  /s/ T.A. Leach
                                     -------------------------------------
                                     T.A. Leach, Executive Vice President

                                PARKER & PARSLEY GAS PROCESSING CO.,
                                 Trustee of Three Rivers Pipeline Business
                                   Trust


                                By:  /s/ T.A. Leach
                                     -------------------------------------
                                     T.A. Leach, Vice President


                                PURCHASER:

                                COSTILLA PETROLEUM CORPORATION


                                By:  /s/ Michael J. Grella
                                     -------------------------------------
                                     Michael J. Grella, President

                                COSTILLA ENERGY, L.L.C.


                                By:  /s/ Michael J. Grella
                                     -------------------------------------
                                     Michael J. Grella, President


                                          28

<PAGE>

                                                              EXHIBIT 10.16


                               SUPPLEMENTAL AGREEMENT
                                         TO
                                 PURCHASE AND JOINT
                                EXPLORATION AGREEMENT


This Supplemental Agreement (the "Supplement") to that certain Purchase and 
Joint Exploration Agreement dated February 21, 1996, (the "Agreement") 
between and among Costilla Energy, L.L.C., a Texas limited liability company 
("Costilla"), Costilla Redeco Energy, L.L.C., a Texas limited liability 
company the members of which are Costilla and Costilla Petroleum Corporation 
("Costilla-Redeco"), and Resource Development Company Limited, L.L.C. (DE), a 
Delaware limited liability company ("REDECO"), is entered into this the 7th 
day of August, 1996, between and among Costilla, Costilla-Redeco, and REDECO.

                               R E C I T A L S

     (a)  All terms defined in the Agreement shall have the same meaning when 
used in this Supplement.

     (b)  REDECO has heretofore agreed to assign to Costilla 50% of REDECO's 
rights and obligations under the Concession in accordance with and pursuant 
to the terms of the Agreement for valuable consideration previously received.

     (c)  By this Agreement, Costilla and REDECO are agreeing to modify 
certain provisions of the Agreement as set forth below in satisfaction of 
REDECO's obligation to assign an interest in the Concession to Costilla and 
Costilla-Redeco.


                                    I.

                          MEMBERSHIP IN REDECO


     1.1  MEMBERSHIP OF COSTILLA-REDECO. Costilla-Redeco shall be admitted as 
a member of REDECO effective as of the date hereof with a sharing ratio of 
50%. The Operating Agreement of REDECO (the "Operating Agreement") shall be 
amended concurrently herewith by adoption of the Resolutions of the Members 
of REDECO attached hereto as Exhibit "A" to reflect the addition of 
Costilla-Redeco as a member of REDECO.

     1.2  MEMBERSHIP OF REDECO INTERNATIONAL. The current members of 
REDECO, save and except Costilla-Redeco, will assign their membership interest 
in REDECO to REDECO International Ltd., a company organized under 
the laws of Guernsey ("Internationally"), such that International will have a 
50% membership and ownership interest in REDECO. Costilla-Redeco hereby 
consents to the admission of International as a member of REDECO to the 
extent of the membership interest in REDECO so transferred by other members 
to International.

<PAGE>

Supplemental Agreement
August 7, 1996
Page 2


     1.3  FURTHER AGREEMENT. The parties hereto agree to make further 
revisions in the Operating Agreement as needed to accomplish the following:

     (a)  Incorporate the rights and duties of the parties as contained in 
          the Agreement within the context of the parties doing business as 
          members in a limited liability company,

     (b)  Memorialize the limitation on REDECO that it only shall be 
          permitted to engage in a trade or business outside of the territory 
          of the United States of America,

     (c)  Recognize that International shall succeed to certain of the rights 
          and duties of REDECO under the Agreement since Costilla Redeco is now 
          a member of REDECO,

     (d)  Recognize the obligations of the members of REDECO to manage public 
          announcements in a manner consistent with the securities laws of 
          Canada and the United States, and

     (e)  Address such other items as to which all of the parties agree.


                                       II.

                             RIGHTS OF THE PARTIES


     Until such time as the Operating Agreement is revised as described 
above, the terms of the Agreement shall take precedence over the terms of the 
Operating Agreement as to the rights and obligations of the parties other 
than their relationship as members in a limited liability company. Should the 
parties fail to agree on the further revisions above referenced within thirty 
(30) days hereof, Costilla-Redeco shall after an additional thirty (30) days 
assign its membership interest in REDECO to a designee of International and 
the parties shall be reinstated to all rights and duties recited in the 
Agreement.


                                       III.

                            ASSIGNMENT ON CONCESSION


     Notwithstanding Costilla-Redeco's membership in REDECO, the parties 
hereto agree that they shall each make best efforts to obtain approval by 
Moldova of assignment of a direct interest in the Concession itself to either 
of Costilla-Redeco or International should either such party so request such 
an assignment. Should Costilla-Redeco receive such an approval of assignment, 
it agrees to remain a member in REDECO at least to the minimum extent 
required to preserve the partnership aspects of that limited liability 
company unless a new member can be added without material economic 
disadvantage to either of REDECO or Costilla.

<PAGE>

Supplemental Agreement
August 7, 1996
Page 3


                                   IV.

                           COUNTERPART EXECUTION

     This Supplement is executed in multiple original counterparts and each 
such counterpart shall be deemed an original agreement for all purposes; 
provided no party shall be bound to this Supplement unless and until all 
parties have executed a counterpart.


                                    V.

                                  WAIVER

     No waiver by any party of any one or more defaults by another party in 
the performance of this Supplement or the Agreement shall operate or be 
construed as a wavier of any future default or defaults by the same party, 
whether of a like or of a different character. Except as expressly provided 
in this Supplement or the Agreement no party shall be deemed to have waived, 
released or modified any of its rights under this Supplement or the Agreement 
unless such party has expressly stated, in writing, that it does waive, 
release or modify such right.


EXECUTED as of the day, month and year first set forth above.

                                       COSTILLA ENERGY, L.L.C.

                                       By: /s/ Michael J. Grella
                                          ------------------------------------

                                       Name: Michael J. Grella
                                            ----------------------------------

                                       Title: President and Chief Operating
                                              Officer
                                             ---------------------------------


                                       REDECO DEVELOPMENT COMPANY LIMITED, 
                                       L.L.C. (DE)

                                       By: /s/ William C. Liedtke
                                          ------------------------------------

                                       Name: William C. Liedtke
                                            ----------------------------------

                                       Title: Executive Vice President 
                                             ---------------------------------


                                       COSTILLA REDECO ENERGY, L.L.C.

                                       By: Costilla Energy, L.L.C.

                                       By: /s/ Michael J. Grella
                                          ------------------------------------

                                       Name: Michael J. Grella
                                            ----------------------------------

                                       Title: President and Chief Operating
                                              Officer
                                             ---------------------------------



<PAGE>

                                                      EXHIBIT 10.17

- -------------------------------------------------------------------

                 *      *      *      *        *

                      BONUS INCENTIVE PLAN

                               OF


                      COSTILLA ENERGY, INC.
                    (A DELAWARE CORPORATION)

                 *      *      *      *        *

- -------------------------------------------------------------------



<PAGE>


                        TABLE OF CONTENTS

                        *      *      *        

                      BONUS INCENTIVE PLAN

                               OF

                      COSTILLA ENERGY, INC.


- -----------------------------------------------------------------

SECTION                      SUBJECT                         PAGE
- -------                      -------                         ----

1.   PURPOSE OF PLAN . . . . . . . . . . . . . . . . . . . . .  1

2.   DEFINITIONS . . . . . . . . . . . . . . . . . . . . . . .  1

3.   ADMINISTRATION OF THE PLAN. . . . . . . . . . . . . . . .  2

4.   RESERVES FOR INCENTIVE AWARDS . . . . . . . . . . . . . .  3

5.   PARTICIPATION IN THE PLAN . . . . . . . . . . . . . . . .  4

6.   SELECTION OF PARTICIPANTS FOR INCENTIVE AWARDS. . . . . .  4

7.   AWARDS OF INCENTIVE COMPENSATION. . . . . . . . . . . . .  5

8.   PAYMENT OR DISTRIBUTION OF AWARDS . . . . . . . . . . . .  6

9.   FORFEITURE OF BENEFITS. . . . . . . . . . . . . . . . . .  6

10.  COMPLIANCE WITH SECURITIES LAWS . . . . . . . . . . . . .  6

11.  INCLUSION OF AWARD AS INCOME. . . . . . . . . . . . . . .  7

12.  WITHHOLDING . . . . . . . . . . . . . . . . . . . . . . .  7

13.  AMENDMENT OR TERMINATION. . . . . . . . . . . . . . . . .  8

14.  NO RIGHT TO EMPLOYMENT; OFFICIAL CAPACITY . . . . . . . .  8


<PAGE>


15.  EFFECTIVE DATE AND TERM . . . . . . . . . . . . . . . . .  9






<PAGE>




                      BONUS INCENTIVE PLAN


                               OF


                      COSTILLA ENERGY, INC.



     1.   PURPOSE OF PLAN.  This Bonus Incentive Plan (the
"Plan") is intended to attract and retain individuals of
outstanding competence and to promote the growth and development
of the Company or a Subsidiary (as hereinafter defined) by
providing incentive compensation as a reward for those officers,
directors, employees and advisors of the Company or a Subsidiary
who contribute by their ability, industry, loyalty, ingenuity, or
exceptional service to the management, development achievement of
planned corporate financial and operational goals, and successful
operations of the Company or a Subsidiary.
     2.   DEFINITIONS.     For purposes of the Plan, the
following terms shall have the ascribed meanings unless otherwise
clearly apparent from the context:
          "AWARD" - means a distribution in (i) cash, (ii) shares
of the Common Stock of the Company, or (iii) any combination of
cash and shares of Common Stock to be made to a Participant for a
Fiscal Year as determined in accordance with the provisions of
the Plan.
          "BENEFICIARY" - means a Participant designated by the
Board of Directors to receive an Award.
          "BOARD OF DIRECTORS" - means the Board of Directors of
the Company.


                               1


<PAGE>

          "COMMON STOCK" - means the common stock, $.10 par value
per share, of the Company.
          "COMPANY" - means Costilla Energy, Inc.
          "EMPLOYEE" - means a person who is in the regular
employment of the Company or a Subsidiary as determined by the
personnel rules and practices of the Company or a Subsidiary, as
applicable.
          "FISCAL YEAR" - means the taxable year of the Company
or a Subsidiary ending December 31.
          "PARTICIPANT" - means (i) an officer, director or
advisor of the Company or a Subsidiary as of the last day of the
Fiscal Year or (ii) any Employee who (a) has completed a minimum
of 180 days of service with the Company or a Subsidiary, and (b)
is employed by the Company or a Subsidiary as of the last day of
the Fiscal Year; provided, however, that any such person who owns
ten percent (10%) or more of the outstanding shares of Common
Stock at any time during a Fiscal Year shall not qualify as a
Participant and is not eligible for Awards under the Plan for
that Fiscal Year.
          "PLAN" - means this Bonus Incentive Plan of the
Company.
          "SUBSIDIARY" - means any corporation of which capital
stock possessing fifty percent (50%) or more of the total
combined voting power of all classes of its outstanding capital
stock entitled to vote generally in the election of directors is
owned in the aggregate by the Company directly or indirectly
through one or more Subsidiaries.


                                 2


<PAGE>

     3.   ADMINISTRATION OF THE PLAN.  The Plan shall be
administered by the Board of Directors.  Subject to the express
provisions and limitations of the Plan, the Board of Directors
shall have the authority and power to construe the Plan and to
adopt, prescribe, amend and rescind rules and regulations
relating to the Plan, and to make all determinations necessary or
advisable for administering the Plan, including the selection of
Participants to receive Awards.  No member of the Board of
Directors shall be liable for any action or determination made in
good faith with respect to the Plan.
          All determinations, decisions and directions made or
given by the Board of Directors under the Plan shall be final and
conclusive.  The decision of the Board of Directors on any
question concerning or involving the interpretation or
administration of the Plan shall be final and conclusive, and
nothing in the Plan shall be deemed to give any Participant, his
legal representative or assigns, any right to participate in the
Plan except to such extent, if any, as the Board of Directors may
have determined or approved pursuant to the provisions of the
Plan.
     4.   RESERVES FOR INCENTIVE AWARDS.  In order to fund the
payment of Awards of Common Stock granted to Participants in
accordance with the terms of the Plan, the Company shall
authorize and reserve for issuance under the Plan an aggregate of
100,000 shares of the Common Stock, subject to adjustment as
hereinafter provided.  In addition, in order to fund payment of
Awards of cash granted to Participants pursuant to the Plan, the
Board of Directors may from time to time either (i) establish a
cash reserve out of the general operating funds of the Company in
such amount as the Board of Directors shall in its discretion
determine to be reasonable or advisable or (ii) elect to fund and
distribute such cash Awards directly out of the general operating
funds of the Company.  Subject to any required action by the
stockholders of 

                                 3


<PAGE>

the Company, (a) the number of shares of Common Stock covered by 
and reserved for issuance under the Plan shall be appropriately 
adjusted for any increase or decrease in the number of issued 
shares of Common Stock of the Company resulting from a subdivision 
or consolidation of the shares of Common Stock of the Company or 
the payment of a stock dividend (but only on the Common Stock), 
stock split, or any other increase or decrease in the number of 
such shares effected without receipt of consideration by the 
Company; and (b) if the outstanding shares of Common Stock are 
changed or exchangeable for a different number or kind of shares of 
stock or other securities of the Company or another entity, then 
there shall be substituted for each share of Common Stock covered 
by and reserved for issuance under the Plan the number and kind of 
shares of stock or other securities into which each outstanding 
share of the Common Stock shall be changed or for which each such 
share shall be exchangeable.
     5.   PARTICIPATION IN THE PLAN.  During the existence of the
Plan, each individual officer, director, Employee, or advisor of
the Company or a Subsidiary shall be eligible to participate in
the Plan for each Fiscal Year in which such individual qualifies
as a Participant as defined in Section 2 hereof.  The Board of
Directors may give due consideration to the recommendations and
comments submitted by officers, managers and department heads of
the Company or a Subsidiary, as applicable, with respect to the
performance of Employees of the Company or a Subsidiary.
     6.   SELECTION OF PARTICIPANTS FOR INCENTIVE AWARDS.  In
determining the Participants who will receive Awards, the Board
of Directors shall consider, among such other factors as it shall
deem relevant, (a) the profitability of the Company or the
Subsidiary, (b) the success of the Company or the Subsidiary in
achieving its projected financial objectives for the Fiscal Year,
(c) 

                                 4


<PAGE>


the Participant's tenure with the Company or Subsidiary, (d)
the Participant's duties and responsibilities, level of
performance, salary level, and contributions to the success of
the Company or the Subsidiary, (e) the abilities and success of
the Participant in aiding and supporting the achievement of
operational or production goals or achieving administrative
expense ratios, (f) the cash position of the Company or
Subsidiary, as appropriate, and (g) such other factors as the
Committee deems appropriate and relevant, including, but not
limited to, the recommendations and comments, if any, submitted
by officers, managers and department heads of the Company or
Subsidiary, as applicable, with respect to the respective
Participants of the Plan.
     7.   AWARDS OF INCENTIVE COMPENSATION.  Within sixty (60)
days after the expiration of each Fiscal Year, the Board of
Directors, after considering the factors set forth in Section 6,
shall determine (i) the Beneficiaries who shall be entitled to
receive Awards for such Fiscal Year, (ii) the amount of the Award
to be paid or distributed to each Beneficiary for such Fiscal
Year, and (iii) whether such Award shall be made in cash, shares
of Common Stock or a combination thereof.  The amount of the
Award shall be distributed by the Company to each designated
Beneficiary as specified in Section 8 hereof.  The Company shall
not be liable for interest on any Award of cash granted under the
Plan.  An Award in Common Stock shall not entitle the Beneficiary
to have any shares registered or recorded in the Beneficiary's
name, nor shall such Beneficiary have any rights as a stockholder
with respect to such shares, until such time as a stock
certificate evidencing such shares is delivered to him or her
pursuant to the terms of the Award and this Plan.  No Beneficiary
to whom an Award has been made shall have any rights to the Award
other than to receive the Award at the time and in the form
specified by the Board of Directors, which right may not be
assigned or transferred except by will or by the laws of descent


                                 5


<PAGE>


and distribution.  Unless a Beneficiary has filed written
instructions with the Company to the contrary, any Award payable
with respect to a deceased Beneficiary shall be paid to the
Beneficiary's surviving spouse, if any; otherwise, such Award
shall be paid to the Beneficiary's estate.
     8.   PAYMENT OR DISTRIBUTION OF AWARDS.  Awards of any
Fiscal Year shall be in cash or in shares of Common Stock or a
combination of cash and shares of Common Stock, as the Board of
Directors shall determine in its sole discretion.  Any Award
which becomes payable or distributable pursuant to the Plan shall
be paid or distributed to the designated  Beneficiary as soon as
administratively feasible and  practicable after the approval
thereof by the Board of Directors.
     9.   FORFEITURE OF BENEFITS.  Any officer, director,
Employee or advisor of the Company or Subsidiary, as applicable,
who fails for any reason to qualify as a Participant of the Plan,
shall not be eligible to participate in the Plan, or having
initially qualified as a Participant, but thereafter for any
reason ceases to so qualify as specified in Section 2 hereof,
shall forfeit his or her participation in the Plan and shall not
be entitled to any Award for such Fiscal Year, unless the Board
of Directors shall specifically determines otherwise. 
Notwithstanding the preceding, in the event of  such
disqualification by death or permanent disability of a
Participant, the Board of Directors shall determine whether an
Award should be paid or distributed to such Participant.  The
determination of the Board of Directors in the exercise of its
sole discretion shall be final and binding upon anyone claiming
by or through such a Participant.
     10.  COMPLIANCE WITH SECURITIES LAWS.  At the time of any
Award of shares of Common Stock under the Plan, the Company may
require the Beneficiary thereof to execute any documents or take
any action which may be then necessary to comply with the
Securities Act of 


                                 6


<PAGE>

1933, as amended (the "Securities Act") and the
rules and regulations promulgated thereunder, or any other
applicable federal or state laws regulating the sale and issuance
of securities.  
     11.  INCLUSION OF AWARD AS INCOME.  The amount of any Award
granted to a Beneficiary under the Plan shall be subject to
inclusion in the gross income of the Beneficiary in the year such
Award is paid or distributed to the Beneficiary.  Any such Award
of Common Stock shall be reported as income in an amount equal to
the fair market value of such Common Stock as of the date such
Common Stock is awarded to the Beneficiary.  The fair market
value shall be deemed to be the closing price of the Common Stock
on The Nasdaq Stock Market's National Market on the day the Award
in Common Stock is granted or, if no sale of the Common Stock of
the Company is reported on such market on such day, on the next
preceding day on which a closing price is reported.
     12.  WITHHOLDING.  Whenever a Beneficiary shall recognize
compensation income as a result of an Award of cash granted under
the Plan, the Company shall deduct and withhold the applicable
federal income and employment tax withholding due on such cash
Award and remit such withheld amount to the Internal Revenue
Service in accordance with the applicable provisions of the
Internal Revenue Code (the "Code") and the regulations
promulgated thereunder.  Whenever a Beneficiary shall recognize
compensation income as a result of an Award of Common Stock
granted under the Plan, either (i) the Company shall deduct and
withhold the applicable federal income and employment tax
withholding due on such Award of Common Stock from any Award of
cash that may have been granted to the Beneficiary at the same
time as the Award of Common Stock and remit such withheld amount
to the Internal Revenue Service in accordance with the applicable
provisions of the Code and the regulations promulgated
thereunder, or (ii) the 


                                 7


<PAGE>

Beneficiary shall remit in cash to the Company the applicable 
federal income and employment tax withholding which the Company is 
required to remit to the Internal Revenue Service in accordance 
with the applicable provisions of the Code and the regulations 
promulgated thereunder.
     13.  AMENDMENT OR TERMINATION.  The Board of Directors may,
at any time and from time to time without the necessity of
obtaining approval of the stockholders of the Company, amend,
modify, change, suspend, or terminate, in whole or in part, any
or all of the provisions of the Plan, except that no such
amendment, modification, change, suspension, or termination shall
affect any right of any Participant to receive Awards made prior
to the effective date thereof.
     14.  NO RIGHT TO EMPLOYMENT; OFFICIAL CAPACITY.  No
provision contained in this Plan shall be deemed to grant unto
any Participant or his legal representative or assigns, or any
other person or entity claiming under or through a Participant,
any contract or other right to participate in the benefits of the
Plan other than as expressly set forth herein.  Nothing in the
Plan shall be construed as constituting a commitment, guarantee,
arrangement, agreement or understanding of any kind or nature
that the Company or Subsidiary will continue to employ, retain,
elect or designate an individual (whether or not a Participant)
in any capacity; nor shall the Plan affect in any way the right
of the Company or a Subsidiary to terminate the employment,
association, designation or official capacity of any individual
(whether or not a Participant) at any time with or without cause. 
     15.  EFFECTIVE DATE AND TERM.  This Plan shall become
effective upon the closing date of the initial public offering of
the Common Stock of the Company pursuant to the Securities Act
and shall remain in effect until termination by the Board of
Directors.  


                                 8


<PAGE>

     The foregoing Bonus Incentive Plan of Costilla Energy, Inc.
was adopted by the Board of Directors and stockholders of the
Company on the 26th day of August, 1996.

                              COSTILLA ENERGY, INC.


                              By:          
                                   -------------------------------------
   
                                   Michael J. Grella
    
                                   President and Chief Executive Officer





                                       9



<PAGE>


                                                     EXHIBIT 16.1



                     ELMS, FARIS & CO., P.C.


                         August 27, 1996



Securities and Exchange Commission
450 5th Street, N.W.
Washington, D.C. 20549

     Re:  Costilla Energy, Inc.

Gentlemen:

          In September 1995, Costilla Energy, Inc. (the
"Company") changed its principal accountants from Elms, Faris &
Co., P.C. to KPMG Peat Marwick, LLP.  This change of the
Company's principal accountants requires certain disclosures,
pursuant to Item 304(a) of Regulation S-K, in each of the
Registration Statements on Form S-1 filed by the Company on July
26, 1996, file numbers 333-08913 and 333-08909.  Representatives
of Elms, Faris & Co., P.C. have reviewed such disclosure in each
of the Registration Statements, and agree with those statements
made by the Company in response to Item 304(a) of Regulation S-K.

                              Very truly yours,


                              ELMS, FARIS & CO., P.C.




<PAGE>
                                                                    EXHIBIT 23.1
 
                        CONSENT OF INDEPENDENT AUDITORS
 
The Members
Costilla Energy, L.L.C.
 
    We consent to the use of our reports included herein and to the reference to
our firm under the heading "Experts" in the Prospectus.
 
                                          KPMG PEAT MARWICK LLP
 
Midland, Texas
   
August 30, 1996
    

<PAGE>
                                                                    EXHIBIT 23.3
 
                        CONSENT OF INDEPENDENT AUDITORS
 
The Members
Costilla Energy, L.L.C.
 
    We consent to the use of our reports included herein and to the reference to
our firm under the heading "Experts" in the Prospectus.
 
                                          ELMS, FARIS & CO., P.C.
 
Midland, Texas
   
August 30, 1996
    


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