MESA CAPITAL CORP
S-1, 1994-01-14
OIL & GAS FIELD EXPLORATION SERVICES
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<PAGE>   1
 
    AS FILED WITH THE SECURITIES AND EXCHANGE COMMISSION ON JANUARY 14, 1994
                                           REGISTRATION STATEMENT NO. 33-
- --------------------------------------------------------------------------------
- --------------------------------------------------------------------------------
                       SECURITIES AND EXCHANGE COMMISSION
                             WASHINGTON, D.C. 20549

                            ------------------------
 
                                    FORM S-1
            REGISTRATION STATEMENT UNDER THE SECURITIES ACT OF 1933

                            ------------------------
 
                                   MESA INC.
                               MESA OPERATING CO.
                            MESA CAPITAL CORPORATION
           (Exact name of registrants as specified in their charters)
 
<TABLE>
<S>                              <C>                                <C>
             TEXAS                          1311                        75-2394500
           DELAWARE                         1311                        75-2516853
           DELAWARE                         9999                        75-2115388
(State or other jurisdiction of  (Primary Standard Industrial        (I.R.S. Employer
incorporation or organization)   Classification Code Number)        Identification No.)
</TABLE>
 
                          2001 ROSS AVENUE, SUITE 2600
                              DALLAS, TEXAS 75201
                                 (214) 969-2200
    (Address, including zip code, and telephone number, including area code,
                  of registrant's principal executive offices)
 
                               WILLIAM D. BALLEW
                                 301 SOUTH POLK
                             AMARILLO, TEXAS 79101
                                 (806) 378-1000
           (Name, address, including zip code, and telephone number,
                   including area code, of agent for service)
 
                                   Copies to:
                               STEPHEN A. MASSAD
                             BAKER & BOTTS, L.L.P.
                         ONE SHELL PLAZA, 910 LOUISIANA
                              HOUSTON, TEXAS 77002

                            ------------------------
 
     APPROXIMATE DATE OF COMMENCEMENT OF PROPOSED SALE OF THE SECURITIES 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. /X/
 
                                REGISTRATION FEE
 
<TABLE>
<CAPTION>
- --------------------------------------------------------------------------------------------------
- --------------------------------------------------------------------------------------------------
                                                               PROPOSED MAXIMUM
TITLE OF EACH CLASS                           PROPOSED MAXIMUM     AGGREGATE
OF SECURITIES TO BE            AMOUNT TO BE    OFFERING PRICE      OFFERING         AMOUNT OF
  REGISTERED                    REGISTERED       PER NOTE(1)       PRICE(1)     REGISTRATION FEE
- --------------------------------------------------------------------------------------------------
<S>                              <C>                <C>           <C>                <C>
12 3/4% Secured Discount
  Notes due June 30, 1998....    $51,000,000        87.5%         $44,625,000        $15,388
- --------------------------------------------------------------------------------------------------
- --------------------------------------------------------------------------------------------------
</TABLE>
 
 
(1) Estimated pursuant to Rule 457(c) solely for the purpose of calculating the
    amount of the registration fee.
 
     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>   2
 
                             CROSS REFERENCE SHEET
 
                   PURSUANT TO RULE 501(b) OF REGULATION S-K
 
<TABLE>
<CAPTION>
                     ITEM NUMBER AND HEADING                   LOCATION OR CAPTION IN PROSPECTUS
      ------------------------------------------------------   ---------------------------------
<S>   <C>                                                      <C>
  1.  Forepart of the Registration Statement and Outside
      Front Cover Page of Prospectus........................   Outside Front Cover Page of
                                                                 Prospectus
  2.  Inside Front and Outside Back Cover Pages of
      Prospectus............................................   Inside Front and Outside Back
                                                                 Cover Pages of Prospectus;
                                                                 Available Information
  3.  Summary Information, Risk Factors and Ratio of
      Earnings to Fixed Charges.............................   Prospectus Summary; Risk Factors;
                                                                 The Company; Selected Financial
                                                                 Data
  4.  Use of Proceeds.......................................   Prospectus Summary; Use of
                                                                 Proceeds
  5.  Determination of Offering Price.......................   Not Applicable
  6.  Dilution..............................................   Not Applicable
  7.  Selling Security Holders..............................   Not Applicable
  8.  Plan of Distribution..................................   Outside Front Cover Page of
                                                                 Prospectus; Plan of
                                                                 Distribution
  9.  Description of Securities to be Registered............   Outside Front Cover Page of
                                                                 Prospectus; Description of the
                                                                 Secured Notes
 10.  Interests of Named Experts and Counsel................   Legal Opinions
 11.  Information with Respect to the Registrant............   Outside Front Cover Page of
                                                                 Prospectus; Additional
                                                                 Information; Prospectus
                                                                 Summary; Risk Factors; The
                                                                 Company; Unocal Litigation and
                                                                 Settlement; Market Prices of
                                                                 Secured Notes; Historical and
                                                                 Pro Forma Capitalization;
                                                                 Selected Financial Data;
                                                                 Management's Discussion and
                                                                 Analysis of Financial Condition
                                                                 and Results of Operations;
                                                                 Business; Management; Executive
                                                                 Compensation; Security
                                                                 Ownership of Principal Owners
                                                                 and Management; Description of
                                                                 the Secured Notes; Financial
                                                                 Statements
 12.  Disclosure of Commission Position on Indemnification
      for Securities Act Liabilities........................   Not Applicable
</TABLE>
<PAGE>   3
 
     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.
 
                 SUBJECT TO COMPLETION, DATED JANUARY 14, 1994
 
PROSPECTUS
 
                                  $51,000,000
 
                                 {MESA LOGO}


                12 3/4% SECURED DISCOUNT NOTES DUE JUNE 30, 1998

     The 12 3/4% Secured Discount Notes due June 30, 1998 (the "Secured Notes")
are the joint and several obligations of MESA Inc. (the "Company"), Mesa
Operating Co. ("MOC") and Mesa Capital Corporation ("Capital" and, together with
the Company and MOC, the "Obligors"). The Secured Notes do not bear interest
through June 30, 1995. At December 31, 1993, the Accreted Value (as specified in
the terms of the Secured Notes) of each Secured Note was $830.77 and the
aggregate Accreted Value for all Secured Notes offered was $42.4 million. Such
Accreted Value will increase at a rate of 12 3/4% per annum, compounded
semiannually on each June 30 and December 31, through and including June 30,
1995. From and after July 1, 1995, the Secured Notes will accrue interest at a
rate of 12 3/4% per annum, payable only in cash. Interest will be payable
semiannually in arrears on June 30 and December 31 of each year, beginning
December 31, 1995. See "Description of the Secured Notes -- Yield and Interest."
 
     The obligations of the Obligors under the Secured Notes are secured by
liens on the Collateral (as defined) described herein. Such liens are
subordinate to prior liens securing the $69.5 million of obligations under the
revolving credit agreement of the Company and MOC outstanding as of December 31,
1993 and any future first lien debt of the Obligors, subject to the limitations
described herein ("First Lien Debt"). See "Description of the Secured
Notes -- Security." The Secured Notes are senior in right of payment to the
Obligors' outstanding Subordinated Notes (as defined) and subordinate to all
existing and future First Lien Debt of the Obligors. The Secured Notes rank pari
passu with respect to the Obligors' Unsecured Notes (as defined). See
"Description of the Secured Notes -- Ranking." The Secured Notes may be redeemed
at the option of the Obligors, in whole at any time or in part from time to
time, at the redemption prices set forth herein. In addition, the Obligors will
be required to redeem or make an offer to purchase Secured Notes under certain
circumstances. See "Description of Secured Notes -- Mandatory Retirement" and
"-- Change in Control."
 
     The Secured Notes offered hereby will be issued pursuant to the same
indenture under which the Obligors currently have outstanding $569,277,000 face
amount (at maturity) of Secured Notes, which Secured Notes were issued in
connection with the Obligors' recently completed debt exchange offer. The
Secured Notes offered hereby will be fungible with the currently outstanding
Secured Notes. The Secured Notes are not listed for trading on any national
securities exchange, but are traded in the over-the-counter market by certain
dealers who from time to time are willing to make a market in the Secured Notes.
 
     The proceeds of the sale of the Secured Notes offered hereby will be used
to fund all or a portion of the Company's $42.75 million share of the payment to
be made to Unocal Corporation ("Unocal") to settle a lawsuit by Unocal against
the Company and other defendants. The settlement of the lawsuit with Unocal is
subject to court approval, and this Offering will not be consummated unless and
until such court approval is obtained. A hearing before the court is currently
scheduled for               , 1994 to determine the fairness, reasonableness and
adequacy of the settlement and whether it should be approved by the court. See
"Unocal Litigation and Settlement."
 
     The consummation of this Offering is also conditional upon the sale of an
aggregate amount of Secured Notes that would result in proceeds of at least $40
million, before deducting expenses of the Company estimated at $          ,
unless a Prospectus Supplement hereto otherwise provides. The Secured Notes may
be offered and sold at a fixed price or prices, which may be changed, or from
time to time at market prices prevailing at the time of sale, at prices related
to such prevailing market prices or at negotiated prices. Based on discussions
with dealers, the Obligors believe that, as of January 12, 1994, offered prices
by such dealers for Secured Notes were higher than the Accreted Value of the
Secured Notes as of that date.
 
     Offers to purchase Secured Notes are being considered by the Obligors on a
continuing basis. The Obligors may sell Secured Notes directly or through
underwriters or agents acting on a best efforts basis or as otherwise indicated
in a Prospectus Supplement. See "Plan of Distribution." If any agents of the
Obligors or any underwriters are involved in the sale of any Secured Notes in
respect of which this Prospectus is being delivered, the names of such agents or
underwriters and any applicable commissions or discounts will be set forth in a
Prospectus Supplement. The net proceeds to the Obligors from such sale will also
be set forth in a Prospectus Supplement.
 
     SEE "RISK FACTORS" FOR A DISCUSSION OF CERTAIN FACTORS THAT SHOULD BE
CONSIDERED BY PROSPECTIVE PURCHASERS OF THE SECURED NOTES OFFERED HEREBY.

                             ---------------------
 
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 THIS PROSPECTUS. ANY
       REPRESENTATION TO THE CONTRARY IS A CRIMINAL OFFENSE.
 
               THE DATE OF THIS PROSPECTUS IS             , 1994
<PAGE>   4
 
                             ADDITIONAL INFORMATION
 
     The Company has filed with the Securities and Exchange Commission (the
"Commission") a Registration Statement on Form S-1 (the "Registration
Statement") under the Securities Act with respect to the Secured Notes offered
by this Prospectus. This Prospectus constitutes a part of the Registration
Statement and does not contain all of the information set forth in the
Registration Statement, certain parts of which are omitted from this Prospectus
as permitted by the rules and regulations of the Commission. Statements made in
this Prospectus regarding the contents of any contract, agreement or other
document are not necessarily complete. With respect to each contract, agreement
or other document filed with the Commission as an exhibit to the Registration
Statement, reference is made to the exhibit for further information regarding
the contents thereof, and each such statement is qualified in its entirety by
such reference. For further information regarding the Company and the Secured
Notes offered hereby, reference is made to the Registration Statement, including
the exhibits and schedules thereto.
 
     The Registration Statement, including the exhibits and schedules thereto,
are available for inspection at, and copies of such materials may be obtained at
prescribed rates from, the public reference facilities maintained by the
Commission at its principal offices located at Judiciary Plaza, 450 Fifth
Street, N.W., Washington, D.C. 20549 and at its regional offices located at
Northwestern Atrium Center, 500 West Madison Street, Suite 1400, Chicago,
Illinois 60601 and 75 Park Place, 14th Floor, New York, New York 10007.
 
     The Company is subject to the informational requirements of the Securities
Exchange Act of 1934 and in accordance with that Act files reports, proxy
statements and other information with the Commission. Such reports, proxy
statements and other information can be inspected and copied at the principal
and regional offices of the Commission set forth above. Such reports, proxy
statements and other information concerning the Company can also be inspected at
the office of the New York Stock Exchange, 20 Broad Street, New York, New York
10005, the exchange on which the Company's Common Stock and the Subordinated
Notes are listed.
 
                                        2
<PAGE>   5
 
                                    SUMMARY
 
     The following summary is qualified in its entirety by the more detailed
information and financial statements appearing elsewhere in this Prospectus.
Potential investors are urged to read the more detailed information set forth
elsewhere in this Prospectus. A Glossary of frequently used capitalized and
other specialized terms is attached as Annex A (located inside the back cover).
 
MESA
 
     MESA Inc. is one of the largest independent natural gas producers in the
United States. Mesa owns proved natural gas, natural gas liquids and oil
reserves estimated as of December 31, 1992 at approximately 1.8 trillion cubic
feet of natural gas equivalents. Over 70% of Mesa's total equivalent proved
reserves is natural gas and almost all of its other reserves are natural gas
liquids. Substantially all of Mesa's reserves are proved developed reserves.
 
     Mesa's principal producing properties are in the Hugoton field of southwest
Kansas and the West Panhandle field of Texas, which together account for over
95% of Mesa's equivalent proved reserves at December 31, 1992. These two fields
are in the same producing trend and contain shallow natural gas reserves that
are expected to produce beyond the year 2020. The Hugoton field is the largest
producing gas field in the continental United States. Mesa also owns and
operates natural gas processing plants located in both of these fields which are
capable of processing substantially all of Mesa's natural gas production in
these fields. Mesa considers itself one of the most efficient operators of
shallow natural gas properties in the United States.
 
     Mesa holds all of its assets and conducts its operations through its
subsidiaries, all of which are wholly-owned following a January 1994
restructuring that converted the general partner interests in the subsidiaries
to common stock of Mesa. The Company's direct corporate subsidiaries are:
 
     - Mesa Operating Co. ("MOC"), which owns all of Mesa's oil and gas
       properties, other than Mesa's Hugoton field natural gas properties, as
       well as an approximate 81% limited partnership interest in Hugoton 
       Capital Limited Partnership ("HCLP") and certain other assets;
 
     - Mesa Midcontinent Co. ("MMC"), which owns principally cash and
       securities, as well as an approximate 19% limited partnership interest in
       HCLP; and
 
     - Mesa Holding Co. ("MHC"), which owns principally cash, as well as the
       outstanding capital stock of Mesa Environmental Ventures Co. ("Mesa
       Environmental").
 
The Company's other significant subsidiaries, owned indirectly, are:
 
     - HCLP, a limited partnership which owns substantially all of Mesa's
       Hugoton field natural gas properties; and
 
     - Mesa Environmental, which is engaged in promoting the use of natural gas
       as a motor vehicle fuel and developing and marketing natural gas fuel
       equipment for the transportation market.
 
     Capital is a wholly owned finance subsidiary of MOC.
 
     Mesa's business strategy includes (i) continuing its effort to strengthen
its financial condition by raising equity capital and applying the proceeds
thereof to retire debt, and issuing new lower cost debt to refinance its
existing high cost debt securities, (ii) maximizing the value of its existing
high-quality, long-life reserves through efficient operating and marketing
practices, (iii) increasing its capability to process natural gas and to extract
natural gas liquids and helium by expanding and modernizing processing
facilities, (iv) conducting selective exploratory and development activities,
principally in existing areas of operations, and (v) promoting the use of
natural gas as a motor vehicle fuel and developing and marketing natural gas
fuel equipment for the transportation market. See "Business."
 
                                        3
<PAGE>   6
 
PURPOSE OF THE OFFERING
 
     The proceeds of the sale of the Secured Notes offered hereby will be used
to fund all or a portion of Mesa's share of the payment to be made to Unocal
Corporation to settle a lawsuit by Unocal against Mesa and other defendants. See
"Unocal Litigation and Settlement." The Secured Notes will be issued pursuant to
the same indenture (the "Secured Indenture") under which the Obligors currently
have outstanding $569,277,000 face amount (at maturity) of Secured Notes, which
Secured Notes were issued in connection with the Obligors' recently completed
debt exchange offer. The Secured Notes offered hereby will be fungible with the
currently outstanding Secured Notes. The issuance of the additional amount of
Secured Notes offered hereby was expressly contemplated in the Secured Indenture
for the purpose of settling or compromising the Unocal lawsuit. See "Description
of the Secured Notes -- Provisions Relating to the Issuance of the Additional
Secured Notes Offered Hereby."
 
     The Unocal lawsuit was originally filed in 1986 against Mesa Petroleum Co.,
a predecessor of the Company, certain subsidiaries of Mesa Petroleum Co. and
certain other parties. The lawsuit alleged that the defendants had purchased and
sold Unocal common shares within a six-month period in 1985 in transactions
subject to Section 16(b) of the Securities Exchange Act of 1934, resulting in
alleged short-swing profits of approximately $99 million that were recoverable
by Unocal under Section 16(b). The plaintiffs also asked the Court to grant
pre-judgment interest, which amount could currently exceed $50 million. Mesa and
the other defendants contended that none of the transactions in Unocal shares
were subject to Section 16(b) and, further, that no profit was realized.
However, in light of the significant uncertainties relating to continuing the
litigation and other relevant circumstances, Mesa determined that entering into
a settlement agreement with Unocal (the "Settlement Agreement") would be in the
best interests of Mesa and its stockholders.
 
     Pursuant to the Settlement Agreement, the Mesa and the other defendants
have agreed to pay to Unocal an aggregate of $47.5 million, of which $42.75
million will be paid by Mesa and $4.75 million will be paid by certain other
defendants not affiliated with Mesa. The Settlement Agreement is subject to
approval of the Federal District Court for the Central District of California,
following a hearing to determine the fairness, reasonableness and adequacy of
the amounts to be paid pursuant to the Settlement Agreement and whether the
Settlement Agreement should be approved by the Court. Such hearing is currently
scheduled for                , 1994. The Secured Notes offered hereby will not
be issued unless and until such approval is received. See "Plan of
Distribution."
 
     Both the Settlement Agreement and the Exchange Offer described below have
or had as a principal goal the reduction of near term financial risk to Mesa so
as to permit Mesa to undertake, subject to market conditions, an orderly
recapitalization. Mesa will seek to deleverage its balance sheet principally
through the public or private sale of equity securities and the application of
the proceeds therefrom to repay debt, and by reducing the interest expense on
its remaining debt by refinancing such debt at lower rates. Mesa believes that
the combination of the Exchange Offer and the Settlement has removed the actual
and potential requirement for large cash outflows from Mesa until at least
December 1995, at which time Mesa will begin making semiannual cash interest
payments on the Discount Notes, which interest begins accruing on June 30, 1995,
or until June 1996, when Mesa's unsecured discount notes mature.
 
EXCHANGE OFFER
 
     On August 26, 1993, Mesa completed an exchange offer (the "Exchange Offer")
for all of the outstanding 13 1/2% Subordinated Notes due May 1, 1999 (the
"13 1/2% Subordinated Notes") and 12% Subordinated Notes due August 1, 1996 (the
"12% Subordinated Notes" and, together with the 13 1/2% Subordinated Notes, the
"Subordinated Notes") of the Obligors. Pursuant to the Exchange Offer,
approximately $586.3 million aggregate principal amount of Subordinated Notes
were tendered and accepted for exchange, and the Obligors issued approximately
$569.3 million aggregate principal amount ($472.9 million accreted value at
December 31, 1993) of Secured Notes, approximately $178.8 aggregate principal
amount ($148.6 million accreted value at December 31, 1993) of 12 3/4% Discount
Notes due June 30, 1996 (the "Unsecured Notes" and, together with the Secured
Notes, the "Discount Notes") and approximately $29.3 million aggregate principal
amount of 0% Convertible Notes due June 30, 1998 (the "Convertible
 
                                        4
<PAGE>   7
 
Notes"). The terms and provisions of the Secured Notes and the Unsecured Notes
are substantially similar, except with respect to security, maturity and
redemption provisions. Pursuant to the terms of the indenture governing the
Convertible Notes, all of the previously outstanding Convertible Notes have been
converted into approximately 7.5 million shares of the Company's common stock
(the "Common Stock").
 
     The Exchange Offer reduced the Obligors' cash requirements through December
1995, which enhances the Obligors' ability to service their debt obligations and
make capital expenditures from available cash and operating cash flows.
Specifically, completion of the Exchange Offer enabled the Obligors to replace
substantially all of their Subordinated Notes, which in the aggregate had cash
interest requirements of $75 million per year through August 1996, with
securities that do not require interest payments until December 1995. In
exchange for accepting the deferral of interest payments, tendering Subordinated
Noteholders obtained, among other things, second lien security interests in
certain assets to collateralize the Secured Notes received in the Exchange
Offer, improved ranking of their securities relative to non-tendering
Subordinated Noteholders, better covenant protection and debt securities
convertible into equity of the Company.
 
     The Exchange Offer also altered the timing of required principal repayments
by the Obligors. The 12% Subordinated Notes mature in 1996 and the 13 1/2%
Subordinated Notes mature in 1999. The Exchange Offer had the effect of moving
approximately $115 million of scheduled principal payments from 1996 to 1998 and
approximately $293 million of scheduled principal payments from 1999 to 1998. In
addition, the Exchange Offer resulted in exchanging Subordinated Noteholders
receiving Convertible Notes in exchange for a portion of their Subordinated
Notes. The Convertible Notes were convertible into shares of Common Stock at the
option of the holders at any time and by Mesa at any time after November 26,
1993. In December 1993, the Obligors converted all of the outstanding
Convertible Notes into shares of Common Stock. As a result, a portion of each
exchanging Subordinated Noteholder's debt securities was converted into equity.
 
     Concurrently with the Exchange Offer, Mesa's bank lenders agreed to amend
Mesa's Credit Agreement in order to extend the payment of a portion of the
outstanding principal, which otherwise would have matured in June 1994 (or
earlier as a result of the then current default in the payment of interest on
the Subordinated Notes, which default was cured upon completion of the Exchange
Offer), and to amend certain covenants thereunder, including a reduction of
Mesa's tangible adjusted equity requirement. In return, the banks received,
among other things, additional security, earlier payment of a portion of the
outstanding principal and an increase in the rate of interest payable on the
Credit Agreement. Pursuant to the amendments, upon the completion of the
Exchange Offer, Mesa repaid $20.6 million of borrowings under the Credit
Agreement and made additional principal payments of $18.7 million in the fourth
quarter of 1993. The Credit Agreement requires that Mesa make additional
principal payments of $19.5 million in the first half of 1994 and $50 million
(including cash collateralization of $10.4 million in letters of credit) on June
30, 1995.
 
                                  THE OFFERING
 
Issue......................  12 3/4% Secured Discount Notes due June 30, 1998.
 
Yield......................  The yield to maturity of a Secured Note is 12 3/4%,
                               based on the following terms of the Secured Notes
                               (expressed per $1,000 face amount): (i) the
                               Accreted Value of a Secured Note of approximately
                               $830.77 at December 31, 1993, (ii) the increase
                               in Accreted Value of a Secured Note to $1,000
                               from December 31, 1993 through and including June
                               30, 1995, (iii) cash interest payments at 12 3/4%
                               per annum paid semiannually in arrears
                               thereafter, and (iv) the payment of $1,000
                               (representing the Accreted Value as of December
                               31, 1993 of approximately $830.77 plus the
                               cumulative increase in Accreted Value from
                               December 31, 1993 through and including June 30,
                               1995, totaling approximately $169.23) at
                               maturity. The Accreted Value of each $1,000 face
                               amount of Secured Notes at each June 30 and
                               Decem-
 
                                        5
<PAGE>   8
 
                               ber 31 from December 31, 1993 through and
                               including June 30, 1995 is shown in the table
                               below.
 
<TABLE>
<CAPTION>
                                                                                  ACCRETED VALUE
                                                                                  --------------
                                <S>                                               <C>
                                December 31, 1993...............................    $ 830.7709
                                June 30, 1994...................................      883.7326
                                December 31, 1994...............................      940.0705
                                June 30, 1995 and thereafter....................    1,000.0000
</TABLE>
 
Interest...................  The Secured Notes do not bear interest through June
                               30, 1995. However, the Accreted Value of the
                               Secured Notes will increase from December 31,
                               1993 through and including June 30, 1995 at a
                               rate of 12 3/4% per annum, compounded
                               semiannually on each June 30 and December 31. On
                               July 1, 1995, each Secured Note will have a final
                               Accreted Value of $1,000 (or an integral multiple
                               thereof). From and after July 1, 1995 the Secured
                               Notes will accrue interest at a rate of 12 3/4%
                               per annum, payable only in cash. Such interest
                               will be payable semiannually in arrears on June
                               30 and December 31 of each year, beginning
                               December 31, 1995.
 
Obligors...................  The Secured Notes are the joint and several
                               obligations of the Company, MOC and Capital.
 
Security...................  The obligations of the Obligors under the Secured
                               Notes are secured by (i) a mortgage and security
                               agreement granting a second lien on certain
                               properties and related assets and contractual
                               rights of MOC in the West Panhandle field of
                               Texas and (ii) a pledge agreement granting a
                               second lien and security interest in a 65%
                               limited partnership interest in HCLP (which will
                               be increased to approximately 77% upon issuance
                               of the Secured Notes offered hereby), which is
                               part of the limited partnership interest in HCLP
                               owned by MOC. Such liens are subordinate to prior
                               liens to secure the $69.5 million of First Lien
                               Debt (as defined) outstanding under the Credit
                               Agreement at December 31, 1993 and any future
                               First Lien Debt, subject to the limitations
                               described herein. In addition, the right of the
                               Trustee for the Secured Notes to exercise rights
                               with respect to the Collateral is subject to the
                               terms of an Intercreditor Agreement with the
                               collateral agent for the holders of such First
                               Lien Debt. See "Description of the Secured
                               Notes -- Security."
 
Mandatory Retirement.......  In the event that as of August 31, 1994 or August
                               31, 1995, the Obligors have Mandatory Retirement
                               Funds (as defined), the Obligors will be required
                               to redeem or make an offer to purchase Secured
                               Notes with such funds on the terms described
                               herein. The indenture for the Unsecured Notes
                               contains a similar provision, and Mandatory
                               Retirement Funds will first be applied to redeem
                               or offer to purchase all outstanding Unsecured
                               Notes and then to redeem or offer to purchase
                               Secured Notes.
 
Optional Redemption........  The Secured Notes may be redeemed at the option of
                               the Obligors, in whole at any time or in part
                               from time to time, at redemption prices ranging
                               from a current price of 110.25% of the Accreted
                               Value thereof at the redemption date and
                               declining on a semiannual basis to 100% at July
                               1, 1996, as set forth herein, plus accrued
                               interest thereon to the redemption date if such
                               date is on or after July 1, 1995.
 
                                        6
<PAGE>   9
 
Change in Control..........  In the event of a Change in Control (as defined),
                               the Obligors will be required to make an offer to
                               purchase all of the Secured Notes, (a) at a price
                               equal to 101% of the Accreted Value thereof on
                               the date of purchase if such date is on or prior
                               to June 30, 1995, and (b) at a price equal to
                               101% of the face amount thereof plus accrued
                               interest thereon to the date of purchase if such
                               date is on or after July 1, 1995.
 
Covenants..................  The Secured Indenture restricts, among other
                               things, the ability of the Obligors to acquire
                               Subordinated Notes, incur additional First Lien
                               Debt and other Debt, pay dividends or
                               distributions on the capital stock of the
                               Company, make investments and make changes in
                               their business. The Secured Indenture also
                               restricts the ability of the Obligors to dispose
                               of Collateral.
 
Ranking....................  The Secured Notes are senior in right of payment to
                               the Obligors' Subordinated Notes and subordinate
                               to all existing and future First Lien Debt of the
                               Obligors. The Secured Notes rank pari passu with
                               respect to the Unsecured Notes. As of December
                               31, 1993, the Obligors had $69.5 million of First
                               Lien Debt outstanding, consisting of $59.1
                               million of borrowings and $10.4 million of letter
                               of credit obligations under the Credit Agreement.
                               In addition, HCLP had outstanding $541.6 million
                               of secured notes at December 31, 1993, which,
                               because HCLP is not an obligor under the Secured
                               Notes, are structurally senior to the Secured
                               Notes with respect to the assets of HCLP. As of
                               December 31, 1993, $178.8 million face amount (at
                               maturity) of Unsecured Notes was also
                               outstanding.
 
Market for Secured Notes...  The currently outstanding Secured Notes are traded
                               in the over-the-counter market by certain dealers
                               who from time to time are willing to make a
                               market in Secured Notes. Prices and trading
                               volume of the Secured Notes in the
                               over-the-counter market are not reported and are
                               difficult to monitor. See "Market Prices of
                               Secured Notes." The Secured Notes offered hereby
                               will be fungible with the currently outstanding
                               Secured Notes.
 
                                        7
<PAGE>   10
 
                         SELECTED FINANCIAL INFORMATION
 
     The following table sets forth summary selected historical financial and
operating information of Mesa as of the dates and for the periods indicated
(dollar amounts in thousands, except per share data and ratios). This table
should be read in conjunction with the Consolidated Financial Statements of the
Company and the related notes thereto included elsewhere in this Prospectus.
 
<TABLE>
<CAPTION>
                                NINE MONTHS ENDED
                                  SEPTEMBER 30                               YEARS ENDED DECEMBER 31
                             -----------------------     ---------------------------------------------------------------
                              1993(a)       1992(a)       1992(a)       1991(a)        1990          1989        1988
                             ---------     ---------     ---------     ---------     ---------     ---------   ---------
<S>                          <C>           <C>           <C>           <C>           <C>           <C>         <C>
RESULTS OF OPERATIONS:
  Revenues.................. $ 157,029     $ 158,646     $ 237,112     $ 249,546     $ 329,597     $ 326,909   $ 327,310
  Operating income..........    14,426         6,866        26,221        34,128        43,389        28,225      33,984
  Gains (losses) on
    dispositions of
    properties, net of
    impairments.............     9,600        12,250        12,250        33,749       (81,029)       29,113      13,299
  Net income (loss).........   (59,013)      (71,723)      (89,232)      (79,163)     (200,276)      (60,414)     44,181
  Net income (loss)
    per share...............     (1.53)        (1.86)        (2.31)        (2.05)        (5.19)        (1.56)       1.12
  Dividends per share.......        --            --            --            --           .85          6.80        7.30
BALANCE SHEET (AT END OF
  PERIOD):
  Working capital........... $  73,222     $  91,907     $ 102,853     $ 216,875     $   1,790     $ 144,028   $ 386,876
  Property, plant and
    equipment, net.......... 1,217,047     1,306,617     1,280,251     1,330,276     1,810,318     2,063,216   2,293,764
  Total assets.............. 1,560,102     1,704,165     1,676,523     1,832,816     2,168,002     2,625,623   3,000,439
  Long-term debt, including
    current maturities...... 1,268,984     1,286,155     1,286,155     1,310,705     1,521,740     1,631,490   1,581,521
  Minority interest.........     5,412         8,717         7,961        11,815        15,234        24,552      40,311
  Stockholders' equity......   127,053       201,861       184,352       273,584       352,747       585,741     912,832
PRODUCTION AND RESERVES:
  Production:
    Natural gas (MMcf)......    58,082        63,254        89,527       108,522       137,333       137,167     116,414
    Natural gas liquids
      (MBbls)...............     3,341         3,453         4,840         4,725         3,753         3,225       3,304
    Oil and condensate
      (MBbls)...............       496           752           984           767         1,480         2,984       2,975
    Equivalent natural gas
      (MMcfe)...............    81,104        88,484       124,471       141,474       168,731       174,421     154,088
  Estimated proved reserves
    (at end of period):(b)
    Natural gas (MMcf)......                             1,276,049     1,367,968     1,920,797     2,110,219   2,251,295
    Natural gas liquids
      (MBbls)...............                                80,124        79,269        91,787        75,714      79,235
    Oil and condensate
      (MBbls)...............                                 7,268         3,956         9,880        10,881      20,509
    Equivalent natural gas
      (MMcfe)...............                             1,800,401(b)  1,867,318(b)  2,530,799(b)  2,629,789   2,849,759
OTHER DATA:
  Ratio of earnings to fixed
    charges(c)..............    (d)           (d)           (d)           (d)           (d)           (d)          1.44x
  Fixed charges in excess of
    earnings(d)............. $  61,562     $  74,821     $  93,086     $  82,582     $ 208,925     $  49,755          --
  Pro forma fixed charges
    in excess of
    earnings(e)............. $  65,737     $  78,996     $  98,711            --            --            --          --
</TABLE>
 
- ---------------
 
(a) Financial position and results of operations as of and for the nine months
    ended September 30, 1993 and 1992 and the years ended December 31, 1992 and
    1991 reflect the effects of the sales of oil and gas properties and the
    replacement and refinancing of long-term debt in the first half of 1991.
 
(b) In addition to the proved reserves disclosed above, Mesa owned proved helium
    and carbon dioxide (CO2) reserves at December 31 as follows: 1992, 5,634
    MMcf of helium and 46,457 MMcf of CO2; 1991, 5,705 MMcf of helium and 44,837
    MMcf of CO2; 1990, 5,658 MMcf of helium and 44,797 MMcf of CO2. See
    "Business -- Reserves."
 
(c) For purposes of calculating the ratio of earnings to fixed charges, earnings
    consist of net income (loss) after depreciation, depletion and amortization,
    but before fixed charges, income taxes, minority interest and the loss of an
    investment accounted for under the equity method. Fixed charges consist of
    interest expense.
 
(d) Earnings were not adequate to cover fixed charges in the indicated periods.
 
(e) The computations of the pro forma ratio of earnings to fixed charges for the
    year ended December 31, 1992 and for the nine month periods ended September
    30, 1992 and 1993 assume that $42.8 million Accreted Value of additional
    Secured Notes offered hereby was issued on January 1 of the respective
    periods and assume that the general partner's minority interest in Mesa's
    subsidiaries was converted to Common Stock on January 1 of the respective
    periods.
 
                                        8
<PAGE>   11
 
                                  RISK FACTORS
 
     Prospective investors should consider carefully the following factors
relating to the business of the Company and the Offering, together with the
information and financial data set forth elsewhere in this Prospectus, prior to
purchasing any Secured Notes.
 
     Adverse Financial Condition and High Leverage. At September 30, 1993, Mesa
had outstanding approximately $1.2 billion of long-term debt. Mesa's primary
cash requirements, after paying operating expenses and general and
administrative expenses, are principal and interest payments on its debt and
capital expenditures. Over the next two years, Mesa will incur annual cash
interest costs of less than $5 million on the $13.7 million principal amount of
Subordinated Notes outstanding and amounts outstanding under the Credit
Agreement. There are no interest payments due under the Discount Notes until
December 31, 1995. Interest payments on the HCLP Secured Notes are expected to
total approximately $50 million to $55 million per year for the next two years.
Under the Credit Agreement, $18.7 million of principal was paid in the fourth
quarter of 1993, $19.5 million is due in the first half of 1994 and $50 million
is due on June 30, 1995 (including cash collateralization of $10.4 million of
letter of credit obligations). There are no principal payments due under the
Subordinated Notes or the Discount Notes until 1996. The scheduled amortization
of the HCLP Secured Notes is $42.9 million in 1994 and $39.3 million in 1995.
The proceeds from production of HCLP's Hugoton properties are dedicated to
service the HCLP Secured Notes before any cash may be distributed to Mesa.
Mesa's capital expenditure requirements are estimated to be $23.5 million in
1994 and $15.4 million in 1995.
 
     At September 30, 1993, Mesa had $73.2 million of working capital; and cash
and securities totaled $122.2 million. Working capital at that date included a
$37.4 million note receivable, which was collected in October 1993. Of the
$122.2 million of cash and securities, $23.4 million was held at HCLP.
 
     After giving effect to this Offering and the use of proceeds therefrom as
described in "Use of Proceeds" and the conversion of the Convertible Notes into
Common Stock, the Company would have had total pro forma long-term indebtedness
of approximately $1.2 billion at September 30, 1993 (as if such events had
occurred on that date) and pro forma fixed charges in excess of earnings of
$65.7 million and $98.7 million for the nine months ended September 30, 1993 and
the year ended December 31, 1992, respectively (as if such events had occurred
at the beginning of such periods). See "Historical and Pro Forma Capitalization"
and "Selected Financial Information."
 
     During the next two years, Mesa expects to be able to service its debt and
make capital expenditures with cash generated by operating activities and with
existing cash and securities balances. On December 31, 1995, Mesa will begin
making interest payments on the Discount Notes. Assuming no changes in Mesa's
capital structure prior to such date, Mesa will be required to make cash
interest payments related to the Discount Notes totaling approximately $48
million (approximately $51 million if the additional Secured Notes offered
hereby are issued) on December 31, 1995 and payments totaling approximately $84
million (approximately $90 million if the additional Secured Notes offered
hereby are issued) during 1996. In addition, Unsecured Notes in the amount of
$178.8 million and 12% Subordinated Notes in the amount of $6.3 million become
due in mid-1996. Mesa's current financial forecasts indicate that Mesa will be
unable to fund such payments in 1996 with cash flows from operating activities
and existing cash and securities balances. Depending on industry and market
conditions, Mesa may generate cash by selling assets or issuing new debt or
equity securities. However, Mesa has limited ability to sell assets since its
two largest assets, its interests in the Hugoton and West Panhandle fields, are
pledged under long-term debt agreements. After the June 30, 1995 repayment of
the balances outstanding under the Credit Agreement, Mesa would have $82.5
million of first lien borrowing capacity on the West Panhandle field properties.
See "Description of the Secured Notes -- Limitation on Incurrence of First Lien
Debt." Mesa's current business strategy includes continuing its effort to
strengthen its financial condition by raising equity capital and applying the
proceeds thereof to retire debt, and issuing new lower-cost debt to refinance
its existing high cost debt securities. There can be no assurance that Mesa will
be able to raise equity capital or otherwise refinance its debt.
 
     As a result of the potential adverse consequences discussed above relating
to certain principal and interest payments due in 1996 on Mesa's debt, Mesa's
independent public accountants' report, as reissued for this Prospectus,
contains an "emphasis-of-a-matter" paragraph which calls attention to such
matters.
 
                                        9
<PAGE>   12
 
     In addition, the Secured Indenture, as well the indenture governing the
Unsecured Notes and the Credit Agreement, impose operating and financial
restrictions on Mesa. Such restrictions will affect, and in many respects limit
or prohibit, among other things, the ability of Mesa to incur additional
indebtedness, create liens, sell assets, engage in merger and acquisition
transactions and make dividend and other payments. The leveraged position of
Mesa and the restrictive covenants contained in these indentures and the Credit
Agreement could significantly limit the ability of Mesa to respond to changing
business or economic conditions or to respond to substantial declines in
operating results. See "Description of the Secured Notes" and "Management's
Discussion and Analysis of Financial Condition and Results of
Operations -- Capital Resources and Liquidity."
 
     Additional Indebtedness Resulting from Increase in Accreted Value. The
Accreted Value of the Discount Notes will increase from December 31, 1993
through June 30, 1995 at a rate of 12 3/4% per annum, compounded semiannually.
Consequently, the overall indebtedness of Mesa will increase each year through
June 30, 1995 in an amount equal to the increase in the Accreted Value of the
Discount Notes during such year. From December 31, 1993 to June 30, 1995, and
assuming no redemptions, the Accreted Value of each Secured Note and each
Unsecured Note will increase by $169.23, or an aggregate of approximately $126.6
million for all Secured Notes and Unsecured Notes outstanding. Mesa's cash
interest requirements have been substantially reduced as a result of the
Exchange Offer, given that the Discount Notes do not currently bear interest and
will not begin to accrue interest until July 1, 1995, with interest being
payable thereafter semiannually in arrears on each June 30 and December 31,
beginning December 31, 1995.
 
     Litigation. Mesa is involved in certain litigation, including a lawsuit
brought by and on behalf of Unocal seeking recovery of more than $150 million,
which, if decided adversely to Mesa, would have a material adverse effect on
Mesa. Mesa is offering the Secured Notes offered hereby to fund its share of the
settlement payment with respect to the Unocal litigation. See "Unocal Litigation
and Settlement."
 
     Mesa's independent public accountants have included an explanatory
paragraph in their report on Mesa's 1992 Consolidated Financial Statements,
which is included elsewhere in this Prospectus. Such paragraph describes the
Unocal case discussed in the Notes to the Consolidated Financial Statements, and
indicates that an unfavorable judgment would have a material adverse effect on
the Company's financial position and results of operations.
 
     Uncertainty of Natural Gas Prices. Revenues generated from Mesa's
operations are highly dependent upon the sales price of, and demand for, natural
gas and natural gas liquids. As of December 31, 1992, over 70% of Mesa's proved
reserves, calculated on an energy-equivalent basis, were natural gas and
substantially all of its other reserves were natural gas liquids.
 
     In recent years, prices for natural gas have declined for a number of
reasons, including a nationwide oversupply of gas. The average sales price
received by Mesa for natural gas declined from approximately $2.92 per Mcf in
1983 to $1.84 per Mcf in 1987 to $1.46 per Mcf in 1991. Both the 1990/1991 and
1991/1992 winter periods were much warmer than normal resulting in lower heating
season natural gas prices. Aggregate demand for natural gas did, however,
increase each year. Low drilling activity in the U.S. during the past several
years resulted in a failure to replace reserves and Hurricane Andrew disrupted
natural gas supplies from the prolific Gulf Coast region during September and
October of 1992. As a result, 1992 natural gas market prices were higher than in
1991 and the average price received by Mesa for natural gas produced during 1992
was $1.66 per Mcf. The average price received by Mesa for natural gas produced
during the first nine months of 1993 was $1.77 per Mcf.
 
     For 1992, the annual average Gulf Coast Henry Hub cash market price for
natural gas, as reported by Natural Gas Week was $1.80 per MMBtu. For the first
nine months of 1993, the monthly average Gulf Coast Henry Hub cash market price
for natural gas ranged from $1.69 per MMBtu to $2.35 per MMBtu, and the average
of such nine monthly average prices was $2.08 per MMBtu. Mesa cannot predict
whether the recent increase in natural gas prices is likely to continue or
whether such prices will remain at current levels for the remainder of the year
or in future years.
 
     Market prices for natural gas are volatile and are the result of a number
of factors outside of Mesa's control, including changing economic conditions,
governmental regulations, seasonal weather conditions, natural gas storage
levels and markets for alternative energy sources, among other things. Mesa
cannot predict
 
                                       10
<PAGE>   13
 
how developments in these or related areas will affect the markets for natural
gas or how such effects will impact Mesa's operations.
 
     Uncertainty in Estimates of Production. Revenues generated from Mesa's
operations are also highly dependent on the quantities of natural gas and
natural gas liquids sold. Mesa's producing properties in the Hugoton field and
the West Panhandle field are subject to production limitations imposed by state
regulatory authorities, by contracts or both. See "Business -- Properties" for a
discussion of, among other things, the allocation of allowables to Mesa's
properties. Consequently, Mesa's actual future production may be substantially
affected by factors outside of Mesa's control.
 
     Declining Reserve Base. In recent years, the majority of Mesa's capital
expenditures have been dedicated to developing and upgrading its existing
long-life reserve base through infill drilling of its Hugoton reserves,
additions to its compression and gathering system and pipeline interconnects,
and the construction and expansion of gas processing plants. A relatively modest
amount of expenditures have been made to explore for or develop new reserve
positions. Assuming continuance of this capital expenditure policy and absent
substantial positive revisions to its estimated reserves, Mesa expects that its
annual production of reserves will exceed estimated reserve additions in future
years, and that Mesa's reserves will decline accordingly. Mesa expects its
annual production, expressed as a percentage of the prior year-end estimated
reserves, to increase from approximately 6% in 1992 to approximately 11% by
1999.
 
     Estimates of Reserves and Future Net Revenues. Petroleum engineering is not
an exact science. Information relating to Mesa's oil and gas reserves is based
upon engineering estimates. Estimates of economically recoverable oil and gas
reserves and of future net revenues necessarily depend upon a number of variable
factors and assumptions, such as historical production from the area compared
with production from other producing areas, the assumed effects of regulations
by governmental agencies and assumptions concerning future oil and gas prices,
future operating costs, severance and excise taxes, development costs and
workover and remedial costs, all of which may in fact vary considerably from
actual results. For these reasons, 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 revenues expected therefrom prepared by different engineers or by the
same engineers at different times may vary substantially. Actual production,
revenues and expenditures with respect to Mesa's reserves will likely vary from
estimates, and such variances may be material.
 
     The present values of future net revenues referred to in this Prospectus
should not be construed as the current market value of the estimated oil and gas
reserves attributable to Mesa's properties. In accordance with applicable
requirements of the Commission, the estimated discounted future net revenues
from proved reserves are generally based on prices and costs as of the date of
the estimate, whereas actual future prices and costs may be materially higher or
lower. Actual future net revenues also will be affected by factors such as the
amount and timing of actual production, supply and demand for oil and gas,
curtailments or increases in consumption by gas purchasers, changes in
governmental regulations or taxation, the impact of inflation on costs, general
and administrative costs and interest expense. The timing of actual future net
revenues from proved reserves, and thus their actual present value, will be
affected by the timing of both the production and the incurrence of expenses in
connection with development and production of oil and gas properties. In
addition, the 10% discount factor, which is required by the Commission to be
used to calculate discounted future net revenues for reporting purposes, is not
necessarily the most appropriate discount factor based on interest rates in
effect from time to time and risks associated with the oil and gas industry.
 
     Operating Hazards; Limited Insurance Coverage. Mesa is subject to all of
the operating hazards and risks normally incident to drilling for or producing
oil and natural gas and processing and transporting gas, including blowouts,
cratering, pollution and fires, each of which could result in damage to or
destruction of oil and gas wells, producing formations or production, pipeline
or processing facilities or damage to persons or other property. As is common in
the industry, Mesa is not fully insured against all of these risks.
 
     Trading Market. As of December 31, 1993, $569.3 million face value (at
maturity) of Secured Notes was outstanding. The Secured Notes are not listed for
trading on any national securities exchange, but are traded in the
over-the-counter market by certain dealers who from time to time are willing to
make a market in Secured Notes. These Secured Notes are currently traded by
appointment by certain market makers. No assurance can be given that an active
market for the Secured Notes will continue or as to the liquidity of such
 
                                       11
<PAGE>   14
 
market. Accordingly, no assurance can be given that a holder of the Secured
Notes will be able to sell such Secured Notes in the future or as to the price
at which such sale may occur. The liquidity of the market for the Secured Notes
and the prices at which the Secured Notes trade will depend upon the amount of
such issue outstanding, the number of holders thereof, the interest of
securities dealers in maintaining a market in the Secured Notes and other
factors beyond the Obligors' control. In addition, no assurance can be given as
to the relationship that the current market prices of Secured Notes will bear to
the market prices of the Secured Notes after the Offering.
 
     Security for the Secured Notes. The Secured Notes will be secured by (i)
the Mortgage granting a second lien on certain properties and related assets and
contractual rights of MOC in the West Panhandle field of Texas and (ii) the
Pledge Agreement granting a second lien and security interest in an
approximately 77% limited partnership interest in HCLP (which is part of the 81%
limited partnership interest in HCLP owned by MOC). Such liens will be
subordinate to a lien securing the First Lien Debt, which currently consists of
the outstanding obligations under the Credit Agreement. There can be no
assurance that, following an acceleration after an Event of Default (as defined
in the Secured Indenture), the proceeds from the sale of such Collateral
remaining after satisfaction of all amounts owing in respect of First Lien Debt
and allocable to the Secured Notes would be sufficient, either alone or when
combined with proceeds from the sale of other assets not constituting Collateral
and allocable to the Secured Notes, to satisfy all amounts due on the Secured
Notes. The ability of the holders of Secured Notes to realize upon the
Collateral will also be subject to certain limitations in the Secured Indenture,
the Mortgage, the Pledge Agreement and the Intercreditor Agreement dated as of
August 26, 1993 among the Secured Trustee and the collateral agent for the
holders of First Lien Debt and would be further restricted by applicable law in
the event of a bankruptcy proceeding involving one or more of the Obligors. See
"Description of the Secured Notes -- Security." In addition, HCLP has
outstanding HCLP Secured Notes which, because HCLP will not be an Obligor under
the Secured Notes, are effectively senior to the Secured Notes with respect to
the assets of HCLP. The incurrence of First Lien Debt and other additional
indebtedness by the Obligors and their subsidiaries will be restricted by the
Secured Indenture. See "Description of the Secured Notes."
 
     Governmental Regulation and Environmental Matters. Mesa is subject to
various local, state and federal laws and regulations including environmental
laws and regulations. Mesa believes that it is in substantial compliance with
such laws and regulations. However, significant liability could be imposed on
Mesa for damages, clean up costs and penalties in the event of certain
discharges into the environment. See "Business -- Regulation and Prices."
 
     Funding of Change of Control Offer. In the event of a Change in Control (as
defined in the Secured Indenture), the Obligors would be required to make an
offer to purchase all of the Secured Notes. As of September 30, 1993, after
giving effect to the Offering and the application of the net proceeds therefrom,
the Obligors would not have sufficient funds available to purchase all of the
outstanding Secured Notes were they to be tendered in response to an offer made
as a result of a Change in Control. See "Description of the Secured
Notes -- Change in Control."
 
                                       12
<PAGE>   15
 
                                  THE COMPANY
 
     Mesa Entities. The Company is a holding company and conducts its operations
through its subsidiaries. The Company's direct corporate subsidiaries are MOC,
MMC and MHC and its other significant subsidiaries, owned indirectly, are HCLP
and Mesa Environmental. Unless the context otherwise requires, the term "Mesa"
means the Company and its subsidiaries taken as a whole and includes the
Company's predecessors, Mesa Limited Partnership (the "Partnership") and Mesa
Petroleum Co. ("Original Mesa"). Mesa maintains its principal executive offices
at 2001 Ross Avenue, Suite 2600, Dallas, Texas 75201, where its telephone number
is (214) 969-2200. For additional discussion of Mesa's business and its
subsidiaries, see "Business."
 
HISTORY OF MESA
 
     Overview. In 1964, Mr. Pickens founded Mesa to conduct exploration and
drilling activities in the U.S. and Canada. Mesa's reserves grew principally
through drilling until 1969, when Mesa acquired the Hugoton Production Company,
increasing gas reserves by more than 15 times. In the 1970's, exploration and
development activities were focused in Canada, the mid-continent and Permian
Basin areas of the United States, and offshore in the Gulf of Mexico. In 1976,
Mesa also discovered the 200 million barrel Beatrice oil field offshore Scotland
in the North Sea and was the operator of and a 25% owner in such field.
Anticipating changing political climates, in 1979 Mesa sold its properties in
Canada and the North Sea for substantial gains. Proceeds were used to reduce
debt and acquire additional reserves in the Hugoton field. During the early
1980's, Mesa began to consolidate its operations and to reduce its capital
expenditures and used its excess financial capacity to invest in undervalued
companies.
 
     The Partnership was formed in 1985 as the successor to Original Mesa. In
the mid-to-late 1980's, Mesa's operations were primarily focused in the Gulf
Coast and Hugoton areas. At such time, the domestic oil and gas industry was
characterized by increased costs for finding new reserves, excess supplies of
reserves and lower prices for natural gas. Consequently, Mesa reduced
expenditures for exploratory drilling and instead focused on development
activities principally in the Hugoton field. In the process, Mesa reduced its
exploration and development expenditures from a 1981 to 1985 five year total of
$1.1 billion to a 1986 to 1991 six year total of $177 million. Mesa distributed
substantially all of its available operating cash flow to its owners from 1986
through the first quarter of 1990. Mesa suspended the payment of distributions
in 1990 and has not paid any dividends since that time.
 
     Oil and Gas Property Acquisitions. Based on the belief at the time that
purchasing reserves was a more cost efficient method of reserve replacement than
exploratory drilling and that natural gas prices would increase or remain
stable, from 1986 to 1988 Mesa made two major acquisitions which increased its
proved reserves from 1.4 Tcfe to 2.8 Tcfe of natural gas. In 1986, Mesa acquired
the assets of Pioneer Corporation, which were principally located in the West
Panhandle field in Texas, in exchange for equity securities. In 1988, Mesa
formed Mesa Midcontinent Limited Partnership ("MMLP"), the predecessor to MMC,
to acquire the assets and liabilities of Tenneco Inc.'s mid-continent division,
which were primarily located in the Hugoton field and in the mid-continent area
of Oklahoma and Texas.
 
     Financing Activities. Shortly after the Pioneer acquisition in June 1986,
Mesa sold approximately $400 million of additional equity securities in a public
offering, the proceeds of which were added to working capital and used for
general purposes. In August 1986, Mesa issued $300 million of the 12%
Subordinated Notes, the proceeds of which were used to repay bank debt. To fund
the Tenneco property acquisition in late 1988, Mesa Operating Limited
Partnership ("MOLP"), the predecessor to MOC, and MMLP incurred an aggregate of
approximately $700 million in bank debt (a portion of which was repaid
immediately through the resale of certain of the purchased properties). In 1989,
Mesa issued $300 million of the 13 1/2% Subordinated Notes, and used the net
proceeds to repay bank debt.
 
     As the market for natural gas deteriorated during the late 1980's and 1990,
Mesa began actively considering various alternatives to reduce debt and, if
possible, to extend the maturities of the debt under its bank credit facilities.
At December 31, 1990, Mesa's debt aggregated approximately $1.5 billion
(including current maturities), approximately $914 million of which was bank
debt due to be repaid within five years.
 
     Faced with this heavy debt burden and foreseeing little prospect for a
substantial and sustained increase in natural gas prices in the near future,
Mesa decided to sell assets and to refinance a substantial portion of the
 
                                       13
<PAGE>   16
 
bank debt. In the first half of 1991, Mesa sold, for $428 million in cash and
the assumption of approximately $9 million in liabilities, properties in
Oklahoma, Texas, New Mexico and Colorado that had represented about 17% of its
reserves at year-end 1990. The proceeds from the property sales were applied
principally to repay bank debt and increase cash. In June 1991, Mesa formed
HCLP, to which MOLP and MMLP transferred substantially all of their Hugoton
field properties. HCLP also assumed approximately $550 million of bank debt, due
in installments through 1995, secured by Hugoton properties. HCLP then issued
$616.5 million of the HCLP Secured Notes having maturities of up to 21 years and
used the proceeds to repay the bank debt and fund a $66 million liquidity
reserve account. As a result, Mesa was able to extend the maturities of its debt
to more closely match the anticipated production from the Hugoton field
properties. At the same time, Mesa refinanced the remaining $100 million of
outstanding bank debt through the establishment of the Credit Agreement.
 
     As a result of the 1991 asset sales and refinancing, Mesa retired the $914
million in bank indebtedness that had been outstanding at year-end 1990. These
transactions also provided Mesa with $169 million of cash. A portion of these
funds has since been used to supplement Mesa's cash flows to make principal and
interest payments and capital expenditures.
 
     Corporate Conversion. In December 1991, the Partnership effected a
conversion to corporate form (the "Corporate Conversion") by transferring
substantially all of its assets and liabilities to the Company in exchange for
all of the Company's outstanding Common Stock. The Partnership then distributed
the Common Stock to its unitholders and dissolved.
 
     Exchange Offer. On August 26, 1993, Mesa consummated the Exchange Offer,
pursuant to which approximately $586.3 million aggregate principal amount of
Subordinated Notes (and related accrued interest claims) were exchanged for
Secured Notes, Unsecured Notes, Convertible Notes and cash. Mesa believes that
the Exchange Offer has decreased Mesa's near term financial risk and increased
the likelihood that Mesa will realize the benefits of expected greater cash flow
and asset value to the extent natural gas prices increase. In particular,
completion of the Exchange Offer and the related amendment to Mesa's Credit
Agreement have reduced Mesa's cash requirements through December 31, 1995. See
"Management's Discussion and Analysis of Financial Condition and Results of
Operations."
 
     Subsidiary Restructuring. Effective January 5, 1994, in order to simplify
Mesa's organizational and capital structure, Mesa effected a series of mergers
which resulted in the conversion of each of Mesa's subsidiary partnerships,
other than HCLP, into corporate form. Pursuant to these mergers, MOLP was merged
into MOC, MMLP was merged into MMC, Mesa Holding Limited Partnership ("MHLP"),
the predecessor of MHC, was merged into MHC, and Mesa Environmental Ventures
Limited Partnership ("MEVLP") was merged into Mesa Environmental. Pursuant to
these mergers, all of the general partner interests in the Company's subsidiary
partnerships held directly or indirectly by Boone Pickens were converted into
the number of shares of Common Stock of the Company contemplated by the
Conversion Agreement dated December 31, 1991, between the Company and Mr.
Pickens. As a result, all of Mesa's subsidiaries are now wholly owned by the
Company. Unless the context otherwise requires, the terms "MOC", "MMC", "MHC"
and Mesa Environmental include their predecessors, MOLP, MMLP, MHLP and MEVLP,
respectively.
 
                                       14
<PAGE>   17
 
                        UNOCAL LITIGATION AND SETTLEMENT
 
THE UNOCAL LITIGATION
 
     In 1986, Original Mesa and certain other parties were sued in the Federal
District Court for the Central District of California by David Colan ("Colan"),
a purported stockholder of Unocal, in a lawsuit styled Colan, et al. v. Mesa
Petroleum Co., et al. Unocal, originally named as a nominal defendant, was
subsequently realigned as a plaintiff in the case. Pursuant to Section 16(b) of
the Securities Exchange Act of 1934, plaintiffs allege that "short-swing
profits" allegedly realized upon disposition of certain shares of Unocal common
stock in 1985 are recoverable by Unocal from the defendants. As a result of the
reorganization of Original Mesa into the Partnership and the subsequent
reorganization of the Partnership into the Company, the Company and MOLP assumed
responsibility for this lawsuit. In 1993, the Court granted a motion by Unocal
to add certain other affiliates of the Company as additional defendants.
 
     Under Section 16(b), any profit realized by a holder of more than 10% of a
listed equity security from any purchase and sale of such security within any
period of less than six months is recoverable by the issuer of such security,
provided the holder owned more than 10% of such security immediately prior to
both the purchase and sale in question. In 1984 and 1985, Mesa Partners II, a
general partnership in which a subsidiary of Original Mesa was a general partner
with a 90% interest, purchased 23.7 million Unocal shares, or approximately
13.6% of the total shares then outstanding. The last 6.7 million of these shares
were purchased in a single block trade from a dealer as principal in March 1985
at $48.10 per share. Prior to such purchase, Mesa Partners II owned
approximately 9.8% of the outstanding Unocal shares. In May 1985, Mesa Partners
II tendered its 23.7 million Unocal shares to a Unocal exchange offer.
Thereafter, it entered into a settlement agreement with Unocal which, among
other things, permitted Mesa Partners II to participate in the exchange. In the
exchange, Mesa Partners II received $565 million aggregate principal amount of
Unocal senior notes (equivalent to $72 per share in respect of 7.8 million
shares) and 15.9 million Unocal shares that traded immediately thereafter at per
share prices in the low $30's.
 
     Plaintiffs allege that the 6.7 million shares purchased in March 1985 were
purchased not in a single purchase but rather in multiple purchases, with the
dealer acting as agent for Mesa Partners II. The defendants deny that
allegation. In 1989, the District Court found that there were material issues of
fact in dispute on such question and thus denied a motion by the defendants for
summary judgment on that issue.
 
     In 1990, the District Court held that the disposition of Unocal stock by
the defendants was not a "sale" under Section 16(b) because it was an unorthodox
transaction with no potential for speculative abuse, and thus the Court granted
an opinion in favor of the defendants for judgment in the case. Following an
appeal by the plaintiffs, the U.S. Court of Appeals for the Ninth Circuit
reversed that ruling in 1991 and further held that the plaintiffs were entitled
to a summary judgment to the effect that the disposition of the stock was a
Section 16(b) sale. The U.S. Supreme Court denied the defendants' petition for a
writ of certiorari in May 1992.
 
     The case was then remanded to the District Court for disposition of the
remaining issues. In November 1992 the defendants moved for summary judgment
that a 1985 settlement agreement between the Mesa Defendants and Unocal released
the defendants from any potential liability in the case. In March 1993, the
Court denied the defendants' motion and granted the plaintiffs' cross-motion
holding that, as a matter of law, the settlement agreement did not release the
claim asserted by Unocal in the lawsuit.
 
     Plaintiffs also alleged that at least 3.7 million shares are subject to
Section 16(b) and that Unocal is entitled to recover alleged profits of
approximately $99 million plus prejudgment interest (which at the Court's
discretion may or may not be granted to a successful Section 16(b) plaintiff) in
an amount currently exceeding $50 million. Mesa would have no liability in the
case if it prevailed on either of the following grounds: (i) that the 1985
acquisition of the 6.7 million shares of Unocal was, as Mesa contends, effected
in a single purchase, or (ii) that the Mesa Defendants realized no profit on the
disposition of any Unocal shares that might be deemed subject to Section 16(b).
 
     Since remand of the case to the District Court in mid-1992, trial of the
case had been repeatedly delayed by the Court due to the Court's calendar. Most
recently, the District Court had set a trial date of February 22, 1994, but the
Court had indicated that further delay was a possibility.
 
                                       15
<PAGE>   18
 
THE SETTLEMENT AGREEMENT
 
     The Settlement Agreement was entered into on January 11, 1994 between (i)
Unocal and Colan, (ii) the Company and certain of its affiliates and (iii) the
other partners of Mesa Partners II and certain of their affiliates
(collectively, the "Unaffiliated Entities").
 
     Under the terms of the Settlement Agreement, Mesa and the Unaffiliated
Entities will pay Unocal an aggregate of $47,500,000, with $42,750,000 of such
amount to be paid by Mesa and $4,750,000 to be paid by the Unaffiliated
Entities. In return, the lawsuit will be dismissed with prejudice.
 
     The Settlement Agreement provides that the Settlement amount will be paid
in cash, together with interest on such amount from a specified number of days
after the Judgment Date to the date of payment at an annual rate of 10% (or in
certain events 12%). Payment is to be made under the Settlement Agreement on the
earliest date after the Judgment Date upon which Mesa can complete the issuance
and sale of the Secured Notes referred to in the Settlement Agreement (i.e., the
Secured Notes offered hereby), but in any event not later than 60 calendar days
after the Judgment Date. The term "Judgment Date" means the day on which the
Court enters a judgment approving the Settlement.
 
     The Settlement Agreement contemplates that Mesa will issue and sell to one
or more third parties Secured Notes in an aggregate principal amount sufficient
to generate cash proceeds equal to all or substantially all of the portion of
the Settlement amount payable by Mesa. The Settlement Agreement provides that if
Mesa is unable to effect such a sale by the 60th day after the Judgment Date,
then, unless the parties otherwise agree, the Settlement Agreement will
terminate and the parties will jointly request the Court to set the earliest
practicable trial date.
 
     A hearing before the District Court is currently scheduled for          ,
1994 to determine the fairness, reasonableness and adequacy of the Settlement
and whether it should be approved by the Court. Unocal security holders will be
given notice of the hearing and will be entitled to appear at the hearing and to
object to the fairness, adequacy and reasonableness of the Settlement. Any such
objecting security holder may be entitled to appeal any order of the District
Court approving the Settlement. The Settlement Agreement contemplates the
Settlement would be consummated upon approval by the District Court
notwithstanding any such objection or appeal. In the event any such appeal were
to be filed and were to result in reversal of the District Court's approval, the
Settlement Agreement contemplates that the parties would be restored to their
pre-Settlement positions and the lawsuit reinstated.
 
                                USE OF PROCEEDS
 
     The net proceeds to be received by the Company from the sale of the Secured
Notes offered hereby are estimated to be approximately $     million. The net
proceeds of the Offering will be used, together with cash on hand, to fund
Mesa's $42.75 million share of the settlement payment with respect to the Unocal
lawsuit. See "Unocal Litigation and Settlement."
 
                         MARKET PRICES OF SECURED NOTES
 
     The Secured Notes are traded in the over-the-counter market by certain
dealers who from time to time are willing to make a market in such securities.
Prices and trading volume of the Secured Notes in the over-the-counter market
are not reported and are difficult to monitor. To the extent that Secured Notes
are traded, prices may fluctuate widely depending on, among other things, the
trading volume and the balance between buy and sell orders. See "Risk
Factors -- Trading Market."
 
                                       16
<PAGE>   19
 
                    HISTORICAL AND PRO FORMA CAPITALIZATION
 
     The following table sets forth the historical consolidated capitalization
of Mesa as of September 30, 1993 and the pro forma consolidated capitalization
of Mesa as adjusted to give effect to the Offering, as if the Offering had been
consummated on September 30, 1993. In addition, the pro forma consolidated
capitalization of Mesa is adjusted to give effect to (i) the conversion of the
Convertible Notes into Common Stock as discussed at Note (b) below and (ii) the
conversion of the General Partner's interest into Common Stock as discussed at
Note (c) below, as if such transactions had occurred on September 30, 1993. This
table should be read in conjunction with the Consolidated Financial Statements
of the Company and the related notes thereto included elsewhere in this
Prospectus.
 
<TABLE>
<CAPTION>
                                                                      AS OF SEPTEMBER 30, 1993
                                                                      ------------------------
                                                                      HISTORICAL     PRO FORMA
                                                                      ----------     ---------
                                                                           (IN THOUSANDS)
<S>                                                                   <C>            <C>
Current maturities on long-term debt:
  HCLP Secured Notes................................................  $   42,850    $   42,850
  Credit Agreement..................................................      38,216        38,216
  Other.............................................................       5,305         5,305
                                                                      ----------    ----------
                                                                          86,371        86,371
                                                                      ----------    ----------
Long-term debt:
  HCLP Secured Notes................................................     498,750       498,750
  Credit Agreement..................................................      39,646        39,646
  Secured Notes (a).................................................     458,767       501,517
  Unsecured Notes (a)...............................................     144,124       144,124
  Convertible Notes (b).............................................      27,600            --
  12% Subordinated Notes............................................       6,336         6,336
  13 1/2% Subordinated Notes........................................       7,390         7,390
                                                                      ----------    ----------
                                                                       1,182,613     1,197,763
                                                                      ----------    ----------
Minority interest (c)...............................................       5,412            --
Stockholders' equity (d)............................................     127,053       117,315
                                                                      ----------    ----------
                                                                      $1,401,449    $1,401,449
                                                                      ==========    ==========                     
</TABLE>                                                              
 
- ---------------
 
(a) Represents the Accreted Value at September 30, 1993 of (i) the $569.3
    million face amount (at maturity) of Secured Notes issued in the Exchange
    Offer, (ii) the $178.8 million face amount (at maturity) of Unsecured Notes
    issued in the Exchange Offer and (iii) in the case of the pro forma amount,
    the $42.8 million Accreted Value of Secured Notes offered hereby which are
    assumed to be issued for the purpose of satisfying the Settlement Agreement.
 
(b) Subsequent to September 30, 1993, and pursuant to the terms of the indenture
    governing the Convertible Notes, the outstanding Convertible Notes were
    converted into approximately 7.1 million shares of the Company's Common
    Stock.
 
(c) On January 5, 1994, the Company effected a series of merger transactions
    which resulted in the conversion of MOLP, MMLP and MHLP to corporate form.
    In addition, effective January 5, 1994, all of the General Partner's
    interests were converted to Common Stock, thereby eliminating the minority
    interest.
 
(d) Pro forma stockholders' equity reflects a $42.8 million loss associated with
    the performance of the Settlement Agreement, and the issuances of shares of
    Common Stock as discussed at Notes (b) and (c) above.
 
                                       17
<PAGE>   20
 
                         SELECTED FINANCIAL INFORMATION
 
     The following table sets forth selected financial and operating information
of Mesa as of the dates and for the periods indicated (dollar amounts in
thousands, except per share data). This table should be read in conjunction with
the Consolidated Financial Statements of the Company and the related notes
thereto included elsewhere in this Prospectus.
 
<TABLE>
<CAPTION>
                                    NINE MONTHS ENDED
                                      SEPTEMBER 30                               YEARS ENDED DECEMBER 31
                                 -----------------------   --------------------------------------------------------------------
                                  1993(a)      1992(a)      1992(a)        1991(a)          1990           1989         1988
                                 ----------   ----------   ----------     ----------     ----------     ----------   ----------
<S>                              <C>          <C>          <C>            <C>            <C>            <C>          <C>
RESULTS OF OPERATIONS:
  Revenues...................... $  157,029   $  158,646   $  237,112     $  249,546     $  329,597     $  326,909   $  327,310
  Operating income..............     14,426        6,866       26,221         34,128         43,389         28,225       33,984
  Gains (losses) on dispositions
    of properties, net of
    impairments.................      9,600       12,250       12,250         33,749        (81,029)        29,113       13,299
  Net income (loss).............    (59,013)     (71,723)     (89,232)       (79,163)      (200,276)       (60,414)      44,181
  Net income (loss) per share...      (1.53)       (1.86)       (2.31)         (2.05)         (5.19)         (1.56)        1.12
  Dividends per share...........         --           --           --             --            .85           6.80         7.30
BALANCE SHEET (AT END OF
  PERIOD):
  Working capital............... $   73,222   $   91,907   $  102,853     $  216,875     $    1,790     $  144,028   $  386,876
  Property, plant and equipment,
    net.........................  1,217,047    1,306,617    1,280,251      1,330,276      1,810,318      2,063,216    2,293,764
  Total assets..................  1,560,102    1,704,165    1,676,523      1,832,816      2,168,002      2,625,623    3,000,439
  Long-term debt, including
    current maturities..........  1,268,984    1,286,155    1,286,155      1,310,705      1,521,740      1,631,490    1,581,521
  Minority interest.............      5,412        8,717        7,961         11,815         15,234         24,552       40,311
  Stockholders' equity..........    127,053      201,861      184,352        273,584        352,747        585,741      912,832
PRODUCTION AND RESERVES:
  Production:
    Natural gas (MMcf)..........     58,082       63,254       89,527        108,522        137,333        137,167      116,414
    Natural gas liquids
      (MBbls)...................      3,341        3,453        4,840          4,725          3,753          3,225        3,304
    Oil and condensate
      (MBbls)...................        496          752          984            767          1,480          2,984        2,975
    Equivalent natural gas
      (MMcfe)...................     81,104       88,484      124,471        141,474        168,731        174,421      154,088
  Estimated proved reserves (at
    end of period):(b)
    Natural gas (MMcf)..........                            1,276,049      1,367,968      1,920,797      2,110,219    2,251,295
    Natural gas liquids
      (MBbls)...................                               80,124         79,269         91,787         75,714       79,235
    Oil and condensate
      (MBbls)...................                                7,268          3,956          9,880         10,881       20,509
    Equivalent natural gas
      (MMcfe)...................                            1,800,401(b)   1,867,318(b)   2,530,799(b)   2,629,789    2,849,759
OTHER DATA:
  Ratio of earnings to fixed
    charges(c)..................    (d)          (d)          (d)            (d)            (d)            (d)            1.44X
  Fixed charges in excess of
    earnings(d)................. $   61,562   $   74,821   $   93,086     $   82,582     $  208,925     $   49,755           --
  Pro forma fixed charges
    in excess of earnings(e).... $   65,737   $   78,996   $   98,711             --             --             --           --
</TABLE>
 
- ---------------
 
(a) Financial position and results of operations as of and for the nine months
     ended September 30, 1993 and 1992 and the years ended December 31, 1992 and
     1991 reflect the effects of the sales of oil and gas properties and the
     replacement and refinancing of long-term debt in the first half of 1991.
 
(b) In addition to the proved reserves disclosed above, Mesa owned proved helium
     and carbon dioxide (CO2) reserves at December 31 as follows: 1992, 5,634
     MMcf of helium and 46,457 MMcf of CO2; 1991, 5,705 MMcf of helium and
     44,837 MMcf of CO2; 1990, 5,658 MMcf of helium and 44,797 MMcf of CO2. See
     "Business -- Reserves."
 
(c) For purposes of calculating the ratio of earnings to fixed charges, earnings
     consist of net income (loss) after depreciation, depletion and
     amortization, but before fixed charges, income taxes, minority interest and
     the loss of an investment accounted for under the equity method. Fixed
     charges consist of interest expense.
 
(d) Earnings were not adequate to cover fixed charges in the indicated periods.
 
(e) The computations of the pro forma ratio of earnings to fixed charges for the
     year ended December 31, 1992 and for the nine month periods ended September
     30, 1992 and 1993 assume that $42.8 million Accreted Value of additional
     Secured Notes offered hereby was issued on January 1 of the respective
     periods and assume that the general partner's minority interest in Mesa's
     subsidiaries was converted to Common Stock on January 1 of the respective
     periods.
 
                                       18
<PAGE>   21
 
                    MANAGEMENT'S DISCUSSION AND ANALYSIS OF
                 FINANCIAL CONDITION AND RESULTS OF OPERATIONS
 
     This discussion should be read in conjunction with the Consolidated
Financial Statements of the Company included elsewhere in this Prospectus.
 
RESULTS OF OPERATIONS
 
 NINE MONTHS ENDED SEPTEMBER 30, 1993 COMPARED WITH NINE MONTHS ENDED SEPTEMBER
 30, 1992
 
     Mesa incurred a net loss of $59.0 million for the nine months ended
September 30, 1993 compared with a net loss of $71.7 million for the same period
in 1992.
 
     REVENUES. The following table presents the revenues, production and average
prices from sales of natural gas, natural gas liquids and oil and condensate for
the nine months ended September 30, 1993 and 1992.
 
<TABLE>
<CAPTION>
                                                                      NINE MONTHS ENDED
                                                                        SEPTEMBER 30
                                                                   -----------------------
                                                                     1993           1992
                                                                   --------       --------
    <S>                                                            <C>            <C>
    Revenues (in thousands):
      Natural gas................................................  $101,340       $102,631
      Natural gas liquids........................................    43,781         40,894
      Oil and condensate.........................................     8,743         14,279
    Production:
      Natural gas (MMcf).........................................    58,082         63,254
      Natural gas liquids (MBbls)................................     3,341          3,453
      Oil and condensate (MBbls).................................       496            752
    Average Prices:
      Natural gas (per Mcf)......................................  $   1.76       $   1.59
      Natural gas liquids (per Bbl)..............................     13.06          11.84
      Oil and condensate (per Bbl)...............................     17.49          18.83
</TABLE>
 
     Natural gas revenues for the nine months ended September 30, 1993 and 1992
include losses of $.3 million ($.01 per Mcf) and gains of $6.2 million ($.10 per
Mcf), respectively, related to hedges of natural gas production in the natural
gas futures market.
 
     Natural gas production has declined in 1993 primarily as a result of
decreases in Gulf Coast production. The Company's Hugoton and West Panhandle
field production have increased in 1993. These increases, however, have been
substantially offset by a decrease in gas balancing volumes in the West
Panhandle field. Oil and condensate production has decreased in 1993 as a result
of property sales.
 
     Actual natural gas prices received, excluding the effects of hedging in the
futures market, increased by $.28 per Mcf, or more than 19%, for the nine months
ended September 30, 1993 compared with the same period in 1992. The increases
are attributable to higher spot market prices during each month in 1993 compared
with 1992. Natural gas liquids prices increased for the nine months ended
September 30, 1993 compared to the same period in 1992 primarily due to the
increase in demand for propane caused by the colder 1993 winter.
 
     COSTS AND EXPENSES. Mesa's costs and expenses decreased from $151.8 million
for the nine months ended September 30, 1992 to $142.6 million for the same
period in 1993. Lease operating expenses increased from $31.5 million for the
nine months ended September 30, 1992 to $38.6 million for the same period in
1993 primarily as a result of increased costs in the West Panhandle field.
Exploration charges decreased from $9.1 million for the nine months ended
September 30, 1992 to $2.2 million for the same period in 1993 as a result of
exploratory dry hole expense in the Gulf Coast area in 1992. Depreciation,
depletion and amortization expenses decreased from $79.6 million for the nine
months ended September 30, 1992 to $70.3 million for the same period in 1993.
This decrease is due primarily to lower production.
 
                                       19
<PAGE>   22
 
     OTHER INCOME (EXPENSE). Interest expense decreased $3.1 million for the
nine months ended September 30, 1993 from the same period in 1992 primarily as a
result of $61.4 million in debt repayments during 1993.
 
     Mesa's results of operations for the nine months ended September 30, 1993
and 1992 were significantly affected by gains on sales of oil and gas properties
and gains and losses from securities transactions. In the nine month period
ended September 30, 1993, Mesa sold certain oil and gas properties resulting in
a net gain of $9.6 million compared with a net gain of $12.3 million on
properties sold in the same period in 1992. Proceeds from sales during the nine
month period ended September 30, 1993 and 1992 totaled $26.1 million and $11.4
million, respectively. Mesa recognized gains from securities transactions of
$5.8 million and $10.5 million for the nine months ended September 30, 1993 and
1992, respectively.
 
     Other income (expense) for the nine months ended September 30, 1993
includes a gain of $13.8 million resulting from collection of $37.4 million from
Bicoastal Corporation ("Bicoastal") in October 1993. During 1993, Mesa expensed
approximately $9.7 million of costs associated with the completion of the
Exchange Offer.
 
  COMPARISON OF YEARS ENDED DECEMBER 31, 1992, 1991 AND 1990
 
     For the years ended December 31, 1992, 1991 and 1990, Mesa reported
consolidated net losses of $89.2 million, $79.2 million and $200.3 million,
respectively. Sales of oil and gas properties have had a significant effect on
the results of operations of Mesa in each of the three years. The following
table presents a summary of the results of operations for Mesa for the years
ended December 31 (in thousands).
 
<TABLE>
<CAPTION>
                                                        1992          1991          1990
                                                      ---------     ---------     ---------
    <S>                                               <C>           <C>           <C>
    Revenues........................................  $ 237,112     $ 249,546     $ 329,597
    Costs and expenses..............................   (210,891)     (215,418)     (286,208)
                                                      ---------     ---------     ---------
    Operating income................................     26,221        34,128        43,389
    Interest expense, net of interest income........   (129,888)     (134,258)     (170,256)
    Other income (expense)..........................      2,185       (12,782)        7,620
                                                      ---------     ---------     ---------
    Loss before results of property sales...........   (101,482)     (112,912)     (119,247)
    Gains (losses) on dispositions of oil and
      gas properties................................     12,250        33,749       (81,029)
                                                      ---------     ---------     ---------
    Net loss........................................  $ (89,232)    $ (79,163)    $(200,276)
                                                      ---------     ---------     ---------
                                                      ---------     ---------     ---------
</TABLE>
 
     In 1992, Mesa sold oil and gas properties located in Canada and in 1991
sold properties located primarily in Oklahoma, the Texas Panhandle and the San
Juan Basin of New Mexico. Losses associated with Oklahoma and Texas Panhandle
properties sold in 1991 were accrued in the fourth quarter of 1990. Property
sales in 1990 consisted primarily of natural gas processing plants in Oklahoma.
Proceeds from these sales were used to reduce long-term debt and increase cash.
Results of operations related to sold properties are included in Mesa's results
through the closing dates of such sales. The following table presents the
contribution made to the operating results of Mesa by the sold properties, for
each of the three years ended December 31 (dollars in thousands).
 
<TABLE>
<CAPTION>
                                                          1992         1991         1990
                                                        ---------    ---------    ---------
    <S>                                                 <C>          <C>          <C>
    Revenues..........................................  $   1,398    $  20,362    $ 116,366
    Production costs..................................       (295)      (8,127)     (29,259)
                                                        ---------    ---------    ---------
                                                        $   1,103    $  12,235    $  87,107
                                                        ---------    ---------    ---------
                                                        ---------    ---------    ---------
    Proceeds from sales...............................  $  11,424    $ 428,063    $  40,098
                                                        ---------    ---------    ---------
                                                        ---------    ---------    ---------
    Production:
      Natural gas (MMcf)..............................        521        7,252       39,297
      Natural gas liquids (MBbls).....................         22          176          671
      Oil and condensate (MBbls)......................         24          139          815
    Reserves sold (MMcfe).............................     19,435      414,063       12,610
</TABLE>
 
                                       20
<PAGE>   23
 
     REVENUES. The following table presents the revenues, production and average
prices related to Mesa's sales of natural gas, natural gas liquids and oil and
condensate for the years ended December 31 (dollars in thousands, except per Mcf
and per Bbl data).
 
<TABLE>
<CAPTION>
                                                             1992        1991        1990
                                                           --------    --------    --------
    <S>                                                    <C>         <C>         <C>
    Revenues:
      Natural gas........................................  $157,672    $169,907    $232,220
      Natural gas liquids................................  $ 59,669    $ 62,031    $ 55,507
      Oil and condensate.................................  $ 18,701    $ 16,111    $ 33,780
    Production:
      Natural gas (MMcf).................................    89,527     108,522     137,333
      Natural gas liquids (MBbls)........................     4,840       4,725       3,753
      Oil and condensate (MBbls).........................       984         767       1,480
    Average Price:
      Natural gas (per Mcf)..............................  $   1.72    $   1.54    $   1.61
      Natural gas liquids (per Bbl)......................  $  12.32    $  13.07    $  14.57
      Oil and condensate (per Bbl).......................  $  18.86    $  20.23    $  22.28
</TABLE>
 
     Natural gas revenues reported above include gains of $5.6 million ($.06 per
Mcf) in 1992, gains of $8.3 million ($.08 per Mcf) in 1991 and losses of $1.0
million ($.01 per Mcf) in 1990, related to hedges of natural gas production in
the natural gas futures market.
 
     Natural gas production decreased by 21% from 1990 to 1991 and by an
additional 18% from 1991 to 1992. The aggregate two-year decrease totaled almost
48 Bcf or 35%. The decrease from 1990 to 1991 resulted primarily from sales of
oil and gas properties in early 1991. The 1991 to 1992 decrease resulted
primarily from Mesa's reduced share of allowables in the Hugoton field. West
Panhandle field production increased in each of 1991 and 1992 and partially
offset the aggregate production decreases in other areas. Effective January 1,
1991, Mesa and Colorado Interstate Gas Company ("CIG") entered into a contract
which entitles Mesa to 77% of the ultimate reserves and production from the West
Panhandle field. As a result of this contract, Mesa records its share of the
total field production as revenue, even though its actual sales volumes are
presently less than 77% of the total field production. Entitlement production in
excess of sales totaled 4.8 Bcf in 1991 and 6.8 Bcf in 1992. See additional
discussion below under "Production Allocation Agreement." The remainder of the
increase in West Panhandle production in 1991 and 1992 is attributable to
additional sales to industrial customers.
 
     Mesa's production from the Hugoton field is affected by the allowables set
for the entire field and by the portion of allowables allocated to Mesa's wells.
Allowables are assigned to individual wells and are influenced by the relative
production, testing and drilling practices of all producers in the field, as
well as the relative pressure and deliverability performance of each well.
Beginning in October 1991 and continuing through 1992, Mesa's share of field
allowables was reduced, causing production to decline nearly 30% from 1990 to
1992. Mesa expects 1993 production to increase to approximately 59 Bcfe from 55
Bcfe in 1992 and for production thereafter to increase substantially as Mesa's
share of field allowables returns to higher historical levels. However, because
Mesa has no control over the actions of other producers, it cannot predict with
certainty the extent or timing of the expected increase.
 
     Natural gas liquids production increased by almost 29% from 1990 to 1992
primarily as a result of increased West Panhandle field production, including
entitlement production as discussed above, partially offset by the decrease in
Hugoton field production. Oil and condensate production decreased from 1990 to
1991 due to sales of oil and gas properties in early 1991. Production increased
in 1992 due to successful development drilling in the Gulf Coast and Rocky
Mountain areas.
 
     Natural gas prices decreased in 1991 compared with 1990 as overall supplies
continued to exceed demand. Both the 1990/1991 and 1991/1992 winter periods were
much warmer than normal resulting in lower heating season natural gas prices.
Aggregate demand for natural gas did, however, increase each year. Low drilling
activity in the U.S. during the past several years resulted in a failure to
replace reserves and Hurricane Andrew disrupted natural gas supplies from the
prolific Gulf Coast region during September and October. As a result, 1992
natural gas market prices were higher than in 1991.
 
                                       21
<PAGE>   24
 
     Oil and condensate prices decreased in 1991 and 1992 reflecting the
continuing downturn in market prices since the end of the Persian Gulf war in
early 1991. Natural gas liquids prices generally fluctuate with oil prices.
 
     Other revenues in 1990 consisted primarily of processing income related to
certain natural gas processing plants owned by Mesa. These plants were sold in
September 1990.
 
     COSTS AND EXPENSES. Mesa's costs and expenses declined by approximately 25%
from 1990 to 1991 primarily as a result of the early 1991 oil and gas property
sales. Costs and expenses in 1992 were slightly lower than in 1991. Exploration
charges were $5.3 million greater in 1992 than in 1991 as a result of
exploratory dry hole expense in the Gulf Coast area in 1992. Depreciation,
depletion and amortization expense was $3 million lower in 1992 than 1991 due
primarily to lower production. Certain components of lease operating expenses
and production and other taxes decreased in 1992 from 1991 as a result of the
1991 property sales. These decreases, however, were substantially offset by an
increase in ad valorem taxes in Kansas and the accrual of production and
gathering costs associated with entitlement production in the West Panhandle
field. See additional discussion below under "Production Allocation Agreement."
 
     OTHER INCOME (EXPENSE). Interest costs decreased $36 million from 1990 to
1991 primarily as a result of $263 million in debt repayments made with proceeds
from property sales. Interest expense decreased $7 million from 1991 to 1992
primarily due to a $49 million decrease in weighted average debt outstanding.
 
     Mesa recognized $6.5 million of expenses in 1991 and $2.1 million in 1992
associated with the conversion to corporate form.
 
     PRODUCTION ALLOCATION AGREEMENT. Effective January 1, 1991, Mesa entered
into a Production Allocation Agreement ("PAA") with CIG which allocates 77% of
reserves and production from the West Panhandle field to Mesa and 23% to CIG.
During 1991, Mesa produced and sold 58% of total production from the field and
61% in 1992; the balance of field production was sold by CIG. Mesa records its
ownership interest in natural gas sales as revenue. The difference between the
net value of production sold by Mesa and the net value of its 77% entitlement is
accrued as a gas balancing receivable. The revenues and costs associated with
such accrued production are included in current year results of operations.
 
     The following table presents the incremental effect on production and
results of operations of entitlement sales recorded in excess of actual sales as
a result of the PAA for the years ended December 31 (dollars in thousands).
 
<TABLE>
<CAPTION>
                                                                    1992        1991
                                                                  --------     -------
        <S>                                                       <C>          <C>
        Revenues accrued........................................  $ 23,270     $17,378
        Costs and expenses accrued..............................    (6,073)     (4,362)
        Depreciation, depletion and amortization................   (10,764)     (7,741)
                                                                  --------     -------
                                                                  $  6,433     $ 5,275
                                                                  --------     -------
                                                                  --------     -------
        Production accrued:
          Natural gas (MMcf)....................................     6,772       4,834
          Natural gas liquids (MBbls)...........................       972         671
</TABLE>
 
     At December 31, 1992, the long-term gas balancing receivable, net of
accrued costs, relating to the PAA was $30.2 million, which is included in other
assets in the consolidated balance sheet. The provisions of the PAA allow for
periodic and ultimate cash balancing to occur. The PAA also provides that CIG
may not take in excess of its 23% share of ultimate production.
 
CAPITAL RESOURCES AND LIQUIDITY
 
  FINANCIAL CONDITION AND CASH REQUIREMENTS
 
     Mesa owns and operates its oil and gas properties through direct and
indirect subsidiaries. HCLP owns substantially all of Mesa's Hugoton field
natural gas properties. HCLP was established in 1991 to own these properties and
to issue the HCLP Secured Notes. The assets and cash flows of HCLP are dedicated
to service HCLP's debt and are not available to pay creditors of the Company or
its subsidiaries other than HCLP.
 
                                       22
<PAGE>   25
 
MOC owns all of Mesa's interest in the West Panhandle field of Texas and the
Gulf Coast and the Rocky Mountain areas. MOC owns an approximate 81% limited
partnership interest in HCLP. Other significant subsidiaries are MMC, which owns
cash and investments as well as an approximate 19% limited partnership interest
in HCLP, and MHC, which owns Mesa's claims against Bicoastal. MHC collected its
$37.4 million note receivable from Bicoastal in October 1993 and collected an
additional $4.6 million from Bicoastal in December 1993, which additional amount
represents interest. MOC, MMC and MHC are the successors to the former
subsidiary partnerships of the Company. The subsidiary partnerships were
converted to corporate form on January 5, 1994, pursuant to a series of merger
transactions. See "The Company."
 
     The following table summarizes certain components of Mesa's financial
position and cash flows as of and for the nine months ended September 30, 1993
(in thousands).
 
<TABLE>
<CAPTION>
                                                                         OTHER
                                                                      SUBSIDIARIES
                                              MOLP(a)       HCLP        COMBINED        TOTAL
                                              --------    --------    ------------    ---------
    <S>                                       <C>         <C>         <C>             <C>
    DEBT
      HCLP Secured Notes....................  $     --    $541,600      $     --      $ 541,600
      Credit Agreement and other............    83,167          --            --         83,167
      Secured Notes.........................   458,767          --            --        458,767
      Unsecured Notes.......................   144,124          --            --        144,124
      Convertible Notes.....................    27,600          --            --         27,600
      12% Subordinated Notes................     6,336          --            --          6,336
      13 1/2% Subordinated Notes............     7,390          --            --          7,390
                                              --------    --------    ------------    ---------
                                              $727,384    $541,600      $     --      $1,268,984
                                              --------    --------    ------------    ---------
                                              --------    --------    ------------    ---------
    Cash and securities(b)..................  $ 17,650    $ 23,422      $ 81,098      $ 122,170
    Note receivable(b)......................        --          --        37,428         37,428
    Working capital (deficit)...............   (23,016)    (22,393)      118,631         73,222
    Restricted cash (in noncurrent
      assets)...............................        --      62,543            --         62,543
    Operating cash flows before interest....  $ 35,485    $ 55,112      $   (872)     $  89,725
    Interest payments, net(c)...............   (27,301)    (51,921)        1,425        (77,797)
                                              --------    --------    ------------    ---------
    Cash flows from operating activities....  $  8,184    $  3,191      $    553      $  11,928
                                              --------    --------    ------------    ---------
                                              --------    --------    ------------    ---------
</TABLE>
 
- ---------------
 
(a) MOLP was merged into MOC on January 5, 1994.
 
(b) Included in working capital (deficit). The note receivable was collected in
     October 1993.
 
(c) Cash interest payments, net of interest income.
 
     The HCLP Secured Notes, for which HCLP is the sole obligor, are secured by
the Hugoton field properties and are due in semiannual installments through
August 2012, but may be repaid earlier depending on the rate of production from
the properties. The Credit Agreement, as amended, is a $90 million credit
facility under which $77.9 million of borrowings and $10.4 million of letter of
credit obligations were outstanding at September 30, 1993. The Credit Agreement
is secured by a first lien on MOC's West Panhandle properties, the Company's
equity interest in MOC and a 65% equity interest in HCLP (to be increased to a
77% interest upon the sale of the Secured Notes offered hereby). Borrowings
under the Credit Agreement are due in various installments through June 1995.
The Company and MOC are obligors under the Credit Agreement. The Secured Notes
are due in 1998 and are secured by second liens on MOC's West Panhandle
properties and a 65% equity interest in HCLP (to be increased to a 77% interest
upon the sale of the Secured Notes offered hereby). The Convertible Notes
outstanding at September 30, 1993 were converted into 7.1 million shares of
Common Stock during the fourth quarter of 1993. The Unsecured Notes are due in
1996. The 12% Subordinated Notes (unsecured debt) have a stated maturity of
August 1996 and the 13 1/2% Subordinated Notes (unsecured debt) have a stated
maturity of May 1999. The Secured Notes, Unsecured Notes and both issues of
Subordinated Notes are obligations of MOC, Capital and the Company. The Secured
Notes and the Unsecured Notes are collectively referred to herein as the
Discount Notes.
 
                                       23
<PAGE>   26
 
     The following tables summarize Mesa's 1992 actual and 1993 through 1996
forecast cash requirements, assuming no changes in capital structure, for
interest, debt principal and capital expenditures (in thousands).
 
<TABLE>
<CAPTION>
                                       ACTUAL                       FORECAST
                                      --------    --------------------------------------------
                                        1992        1993        1994        1995        1996
                                      --------    --------    --------    --------    --------
    <S>                               <C>         <C>         <C>         <C>         <C>
    HCLP
      Interest payments, net(a).....  $ 51,704    $ 50,000    $ 47,500    $ 43,600    $ 39,000
      Principal repayments..........    24,550      39,300      42,900      39,300      45,400
      Capital expenditures(b).......     3,180       6,800      11,200       1,700          --
                                      --------    --------    --------    --------    --------
                                      $ 79,434    $ 96,100    $101,600    $ 84,600    $ 84,400
                                      --------    --------    --------    --------    --------
                                      --------    --------    --------    --------    --------
    MOC
      Interest payments, net(a).....  $ 77,464    $ 27,200    $  3,500    $ 51,000    $ 96,100
      Principal repayments..........        --      41,000      24,800      39,600     185,100
      Capital expenditures(b).......    66,021      27,100      12,300      13,700      15,000
                                      --------    --------    --------    --------    --------
                                      $143,485    $ 95,300    $ 40,600    $104,300    $296,200
                                      --------    --------    --------    --------    --------
                                      --------    --------    --------    --------    --------
</TABLE>
 
- ---------------
 
(a) Cash interest payments, net of interest income.
 
(b) Forecast capital expenditures represent Mesa's best estimate of drilling and
     facilities expenditures required to sustain maximum economic production
     from its existing properties during the forecast period. Contractual
     commitments with a major gas purchaser in the Hugoton field require
     expenditures, primarily for compression, of approximately $7.1 million by
     HCLP during 1993 through 1995. In addition, MOC had contractual commitments
     during 1993 of approximately $25.2 million, primarily related to completion
     of a gas processing plant.
 
     On August 26, 1993, Mesa completed the Exchange Offer whereby new debt
securities (including the Discount Notes) were issued in exchange for
substantially all of the 12% and 13 1/2% Subordinated Notes. The Discount Notes
accrue, but do not pay, interest through June 30, 1995, after which interest
will be payable semiannually in cash, commencing December 31, 1995. The Exchange
Offer results in deferrals of $75 million of annual interest payments which
would have been paid through June 30, 1995.
 
     In connection with the Exchange Offer, Mesa and its bank lenders amended
the Credit Agreement in order to extend the payment of a portion of the
outstanding principal, which was scheduled to mature in June 1994 (or earlier as
a result of the then current default in the payment of interest on the
Subordinated Notes, which default was cured upon completion of the Exchange
Offer), and to amend certain covenants thereunder, including a reduction in
Mesa's tangible adjusted equity requirement. In return, the banks received,
among other things, additional security, earlier payment of a portion of the
outstanding principal and an increase in the rate of interest payable on the
loans.
 
     Mesa's independent public accountants included an explanatory paragraph in
their report on Mesa's 1992 consolidated financial statements which described a
potential debt covenant default under the Credit Agreement, which raised
substantial doubt about Mesa's ability to continue as a going concern. Mesa's
consolidated financial statements were prepared assuming that Mesa will continue
as a going concern. Accordingly, no adjustments were made to the consolidated
financial statements to reflect any possible liquidation of assets which may be
required in the event of bankruptcy. As a result of the completion of the
Exchange Offer and the related amendments to the Credit Agreement, Mesa believes
it will have significantly greater cash flow and available cash balances over
the next two years whether or not production and prices increase. In conjunction
with the filing of this Prospectus, Mesa's independent public accountants
reissued their report on Mesa's 1992 consolidated financial statements. As a
result of the successful completion of the Exchange Offer and the related
amendments to the Credit Agreement, the explanatory paragraph was not included
in the reissued independent public accountants' report.
 
                                       24
<PAGE>   27
 
  DEBT COVENANTS
 
     The amended Credit Agreement contains restrictive covenants which require
Mesa to maintain tangible adjusted equity, as defined, of at least $50 million
and a ratio of cash flow and available cash to debt service, as each is defined,
of at least 1.50 to 1. At September 30, 1993, tangible adjusted equity was $132
million and the ratio was 2.11 to 1. Mesa expects to accrue a loss of
approximately $43 million in the fourth quarter of 1993 representing its share
of the settlement. In addition, assuming no changes in its capital structure,
Mesa expects to continue to report losses from operations in the foreseeable
future.
 
     The indentures governing the Discount Notes restrict, among other things,
Mesa's ability to incur additional indebtedness, pay dividends, acquire stock or
make investments, loans and advances. The amended Credit Agreement also
restricts, among other things, Mesa's ability to incur additional indebtedness,
create liens, pay dividends, acquire stock or make investments, loans and
advances.
 
  LITIGATION AND CONTINGENCIES
 
     The Company and certain other parties are defendants in a lawsuit which
relates to an investment in Unocal in 1985. This lawsuit, more fully described
under "Unocal Litigation and Settlement" and in the Notes to the Consolidated
Financial Statements of the Company, asserts that certain profits allegedly
realized by the defendants upon the disposition of Unocal common stock in 1985
are recoverable by Unocal pursuant to Section 16(b) of the Securities Exchange
Act of 1934. A trial was scheduled to begin February 22, 1994. On January 11,
1994, Mesa entered into the Settlement Agreement whereby the defendants have
agreed to pay to Unocal an aggregate of $47.5 million, of which $42.8 million
will be paid by Mesa and $4.7 million will be paid by certain other unaffiliated
third parties. The Settlement Agreement is subject to approval by the Court,
following notice by Unocal to its security holders. Mesa intends to fund
substantially all of its portion of the settlement amount with proceeds from
issuance of Secured Notes offered hereby. If the Settlement Agreement is not
approved by the Court and the case is ultimately tried, no determination can be
made at this time as to the ultimate outcome of the litigation. If the
plaintiffs were to prevail and were awarded a judgment (including interest) in
the range of their estimate of $150 million, payment of such amount would have a
material adverse effect on Mesa's financial position and results of operations.
Such a payment would remove a substantial amount of cash from Mesa at a time
when cash flows from operating activities may not be sufficient to service debt
and fund capital expenditures and other obligations. Such a payment could also
reduce tangible adjusted equity, as defined, below the Credit Agreement
requirement of $50 million. In the event of an adverse judgment, Mesa could be
required to post an appeal bond or other security in the amount of the judgment
in order to stay execution pending any appeal.
 
     Mesa is also a defendant in various other lawsuits and legal proceedings
and, as the successor entity to the Partnership and Original Mesa, has assumed
certain other obligations from those entities. Mesa does not expect the
resolution of any of these other matters to have a material adverse effect on
its results of operations or financial position. See "Business -- Legal
Proceedings."
 
  COMPANY RESOURCES AND ALTERNATIVES
 
     Mesa's cash flows from operating activities are substantially dependent on
the amount of oil and gas produced and the price received for such production.
Production and prices received from HCLP properties, together with cash held
within HCLP, are expected, under Mesa's current operating plan, to generate
sufficient cash flow to meet HCLP's required principal and interest obligations.
However, HCLP cash flows are not expected to be sufficient to permit HCLP to
distribute any excess cash to MOC and MMC until at least 1995. With the
consummation of the Exchange Offer, production and prices at MOC are expected to
be sufficient to cover its cash interest obligations over the next two years
with cash from operating activities. MOC and Mesa's subsidiaries other than HCLP
may also supplement cash flows from operating activities with available cash and
securities balances.
 
     On December 31, 1995, Mesa will begin making interest payments on the
Discount Notes. Assuming no changes in Mesa's capital structure prior to such
date, Mesa will be required to make cash interest payments related to the
Discount Notes totaling approximately $48 million (approximately $51 million if
the additional Secured Notes offered hereby are issued) on December 31, 1995 and
payments totaling approximately $84 million (approximately $90 million if the
additional Secured Notes offered hereby are issued) during
 
                                       25
<PAGE>   28
 
1996. In addition, Unsecured Notes in the amount of $178.8 million and 12%
Subordinated Notes in the amount of $6.3 million become due in mid-1996. Mesa's
current financial forecasts indicate that Mesa will be unable to fund such
payments in 1996 with cash flows from operating activities and existing cash and
securities balances. Depending on industry and market conditions, Mesa may
generate cash by selling assets or issuing new debt or equity securities.
However, Mesa has limited ability to sell assets since its two largest assets,
its interests in the Hugoton and West Panhandle fields, are pledged under
long-term debt agreements. After the June 30, 1995 repayment of the balances
outstanding under the Credit Agreement, Mesa would have $82.5 million of first
lien borrowing capacity on the West Panhandle field properties. See "Description
of the Secured Notes -- Limitation on Incurrence of First Lien Debt." Mesa's
current business strategy includes continuing its effort to strengthen its
financial condition by raising equity capital and applying the proceeds thereof
to retire debt, and issuing new lower-cost debt to refinance its existing high
cost debt securities. There can be no assurance that Mesa will be able to raise
equity capital or otherwise refinance its debt.
 
     In the event the Settlement of the Unocal Litigation is not approved by the
Court and a subsequent adverse outcome in the Unocal litigation, Mesa could
pursue a variety of options including sales of assets, settlement discussions to
reduce the amount of the award or to limit bond requests or negotiations to
obtain relief from certain debt obligations to banks or noteholders. Mesa could
also consider seeking protection from creditors under the Federal Bankruptcy
Code. Mesa's choice from among its alternatives would depend on numerous factors
including the amount of the judgment, bond or security requirements, Mesa's
financial condition and conditions in the oil and gas industry.
 
OTHER
 
     Mesa recognizes its ownership interest in natural gas sales as revenue.
Actual production quantities sold may be different from Mesa's ownership share
in a given period. Mesa records these differences as gas balancing receivables
or as deferred revenue. Net gas balancing underproduction represented
approximately 1.5% of total equivalent production in the nine months ended
September 30, 1993 compared with 15% during the same period in 1992. The gas
balancing receivable or deferred revenue component of natural gas and natural
gas liquids sales in future periods is dependent on future rates of production,
field allowables and the amount of production taken by Mesa or by its joint
interest partners.
 
     Mesa invests from time to time in marketable equity and other securities
and in commodity and futures contracts, primarily related to crude oil and
natural gas. Mesa also enters into natural gas futures contracts as a hedge
against natural gas price fluctuations.
 
     Management does not anticipate that inflation will have a significant
effect on Mesa's operations.
 
                                       26
<PAGE>   29
 
                                    BUSINESS
 
     Mesa is primarily engaged in the production and development of and
exploration for natural gas and oil in the United States. Mesa's principal
business strategy includes (i) continuing its effort to strengthen its financial
condition by raising equity capital and applying the proceeds thereof to retire
debt, and issuing new lower cost debt to refinance its existing high cost debt
securities, (ii) maximizing the value of its existing high-quality, long-life
reserves through efficient operating and marketing practices, (iii) increasing
its capability to process natural gas and to extract natural gas liquids and
helium by expanding and modernizing processing facilities, (iv) conducting
selective exploratory and development activities, principally in existing areas
of operations, and (v) promoting the use of natural gas as a motor vehicle fuel
and developing and marketing natural gas fuel equipment for the transportation
market.
 
     Mesa considers itself one of the most efficient operators of shallow
natural gas properties in the United States. At December 31, 1992, Mesa owned
approximately 1.8 Tcf of equivalent proved natural gas reserves, making it one
of the largest independent oil and gas companies in the United States. Over 95%
of Mesa's reserves are located in the Hugoton field of southwest Kansas and in
the West Panhandle field of Texas. At December 31, 1992, the estimated future
net cash flows before income taxes from Mesa's proved reserves, as determined in
accordance with the regulations of the Commission, were approximately $2.4
billion and had a net present value before income taxes of approximately $1.2
billion. Over 70% of Mesa's total equivalent proved reserves are natural gas,
and substantially all such reserves are proved developed reserves. The balance
of Mesa's reserves are principally natural gas liquids, which are extracted from
its natural gas through gas processing plants. See "-- Reserves."
 
     At December 31, 1985, Mesa owned approximately 1.4 Tcf of equivalent proved
natural gas reserves. From the end of 1985 through 1988, Mesa increased its
ownership of gas reserves by acquiring approximately 1.1 Tcf of equivalent
proved gas reserves in its 1986 acquisition of Pioneer Corporation and over 500
Bcf of equivalent proved gas reserves in its 1988 acquisition of oil and gas
properties from Tenneco Inc.
 
     During the period from January 1, 1989 through December 31, 1992, Mesa sold
certain producing and undeveloped oil and gas properties in Oklahoma, the Texas
Panhandle, New Mexico, Colorado and Canada for a total of over $600 million. The
reserves associated with the properties sold totaled approximately 564 Bcfe of
natural gas. The substantial portion of these property sales, totaling over 426
Bcfe of natural gas and approximately $430 million, occurred in the first half
of 1991. The proceeds from the sales of oil and gas properties were used
principally to reduce bank debt and to supplement cash reserves.
 
     Mesa conducts its operations through various direct and indirect
subsidiaries, including MOC, MMC, MHC and Mesa Environmental, each a Delaware
corporation, and HCLP, a Delaware limited partnership. HCLP owns substantially
all of Mesa's Hugoton field natural gas properties. MOC owns all of Mesa's other
oil and gas properties as well as an approximate 81% interest in HCLP. MHC and
MMC own principally cash and various investments and, in the case of MMC, an
approximate 19% interest in HCLP. Mesa Environmental is engaged in promoting the
use of natural gas as a motor vehicle fuel and developing and marketing natural
gas fuel systems for the transportation market.
 
                                       27
<PAGE>   30
 
     At December 31, 1993, Mesa employed 383 persons (including 56 persons
employed by HCLP and 44 employed by Mesa Environmental).
 
MOC
 
     MOC's properties account for approximately 677 Bcfe, or 38% of Mesa's total
equivalent proved reserves at December 31, 1992. MOC's properties are located
primarily in the West Panhandle field of Texas, but also include interests in
the Gulf of Mexico offshore Louisiana and Texas, and the Rocky Mountain area.
MOC also owns an approximate 81% limited partnership interest in HCLP. In
addition, MOC owns helium attributable to its West Panhandle field properties,
which it began extracting in early 1993, as well as helium produced from HCLP's
Hugoton properties, which it began extracting in November 1993.
 
     MOC is the Company's principal operating subsidiary. Most of Mesa's
employees are employed by MOC, and MOC is generally responsible for all of
Mesa's operations, administration and marketing, including the operations of
HCLP pursuant to the services agreement described below.
 
     MOC has entered into a services agreement with HCLP pursuant to which MOC
operates HCLP's Hugoton field properties and provides certain services necessary
to market production therefrom, process remittances of production revenues and
perform certain other administrative functions in exchange for a services fee.
The services fee totaled approximately $11 million in 1993.
 
HCLP
 
     HCLP's properties account for 1,123 Bcfe, or 62% of Mesa's total equivalent
proved reserves at December 31, 1992. All of HCLP's proved reserves are in the
Hugoton field in southwest Kansas. Substantially all of Mesa's Hugoton property
interests (including gathering systems, compression and gas processing
facilities, but excluding helium reserves and the deep Hugoton reserves beneath
those owned by HCLP) are owned by HCLP, an indirect wholly owned subsidiary of
the Company. HCLP owns the new Satanta Plant which was constructed by MOC, and
MOC operates the plant under a long-term lease. The plant, which processes
approximately 85% of HCLP's production, was completed in the third quarter of
1993.
 
     HCLP was formed in 1991 to own substantially all of Mesa's Hugoton
properties and to issue the HCLP Secured Notes. The indenture and mortgage for
the HCLP Secured Notes contain various covenants which, among other things,
limit HCLP's ability to sell or acquire oil and gas property interests, incur
additional indebtedness, make unscheduled capital expenditures, make
distributions of property or funds subject to the mortgage, or enter into
certain types of long-term contracts or forward sales of production. The
agreements also require HCLP to maintain a separate existence from the Company.
The assets of HCLP are not available to pay creditors of the Company or its
subsidiaries other than HCLP.
 
OTHER SUBSIDIARIES
 
     MMC does not own any direct interests in oil and gas properties but does
own an approximate 19% limited partnership interest in HCLP. At September 30,
1993, MMC held approximately $42.6 million of cash and securities and also had
an intercompany payable of $59.1 million to MOC.
 
     MHC principally conducts various investment activities. At September 30,
1993, MHC held $37.7 million of cash and securities, and also had recorded
receivables aggregating $37.4 million from Bicoastal, which was collected in the
fourth quarter of 1993. At September 30, 1993, MHC had an intercompany payable
to MOC of $88.7 million.
 
     MHC also owns the equity of Mesa Environmental.
 
     Mesa Environmental was established to promote, expand and participate in
the development of the natural gas vehicle ("NGV") market. See "-- The NGV
Business" below.
 
     Capital is a wholly owned finance subsidiary of MOC.
 
     None of MMC, MHC and Mesa Environmental is an Obligor with respect to the
Secured Notes, the Unsecured Notes or the Subordinated Notes.
 
                                       28
<PAGE>   31
 
PROPERTIES
 
     Mesa's principal properties are in the Hugoton field of southwest Kansas
and the West Panhandle field of Texas, which together account for over 95% of
Mesa's equivalent proved reserves at December 31, 1992. These two fields are in
the same producing trend and contain shallow gas reserves which are expected to
produce beyond the year 2020. The Hugoton field is the largest producing gas
field in the continental United States.
 
  Hugoton Field
 
     Mesa's Hugoton field properties, substantially all of which are owned by
HCLP, accounted for 63% of Mesa's equivalent proved reserves and 67% of the
present value of estimated future net cash flows before income taxes, as of
December 31, 1992. The Hugoton field accounted for approximately 40%, 44% and
39% of Mesa's revenues from the sales of natural gas, natural gas liquids, and
oil for the years ended December 31, 1992, 1991 and 1990, respectively. The
percentage of total Mesa revenues increased in 1991 due to sales of other
properties. Such percentage declined in 1992 as a result of lower production
caused by allowable restrictions discussed below. The percentage of revenues
from the Hugoton field has been less than the percentage of equivalent proved
reserves due primarily to the longer life of the Hugoton properties compared to
Mesa's other properties.
 
     Gas from the Hugoton field is sold in the interstate and intrastate
markets, and thus is subject to state and federal laws and regulations. The
Kansas Corporation Commission (the "KCC") is the state regulatory agency
responsible for setting field market demand (allowables) and prorating
production between wells in the field through the assignment of allowables to
each well. The sale of gas is also subject to the rules and regulations of the
Federal Energy Regulatory Commission (the "FERC").
 
     ALLOWABLE PRODUCTION. Twice each year, the KCC sets the fieldwide allowable
necessary to meet the Hugoton market demand for the summer and winter production
periods. The fieldwide allowable for the Hugoton field increased from 487 Bcf in
1991 to 578 Bcf in 1993.
 
     The fieldwide allowable is allocated among individual wells based on each
well's pressure, deliverability and acreage. The allowables assigned to
individual wells are influenced by the relative production, testing and drilling
practices of all producers in the field, as well as the relative pressure and
deliverability performance of each well.
 
     Generally, fieldwide allowables have been influenced by overall gas market
supply and demand in the U.S., as well as the specific "nominations" for gas
from the parties who produce or purchase gas from the field. The following table
sets forth the fieldwide allowables from 1979 through 1993 and Mesa's
approximate percentage of the fieldwide allowables.
 
<TABLE>
<CAPTION>
                                                               FIELDWIDE         MESA
                                                               ALLOWABLE       ALLOWABLE
        YEAR                                                     (BCF)       PERCENTAGE(1)
        ----                                                   ---------     -------------
        <S>                                                    <C>           <C>
        1979.................................................     692             13.3%
        1980.................................................     517             12.8
        1981.................................................     475             13.0
        1982.................................................     460             12.6
        1983.................................................     325             11.9
        1984.................................................     372             11.5
        1985.................................................     370             11.6
        1986.................................................     377             11.6
        1987.................................................     331             11.8
        1988.................................................     422             12.6
        1989.................................................     467             13.7
        1990.................................................     500             13.6
        1991.................................................     487             12.3
        1992.................................................     516              9.5
        1993.................................................     578              8.5
</TABLE>
 
- ---------------
 
(1) The Mesa Allowable Percentage represents the gross percentage assigned to
    wells operated by Mesa, which approximates Mesa's overall net ownership
    interest in both operated and non-operated properties.
 
                                       29
<PAGE>   32
 
     As the table demonstrates, fieldwide allowables have generally increased
since 1987. However, as a result of the less aggressive production and drilling
practices of other operators in the field between 1989 and 1991, the pressures
and deliverability of Mesa's wells declined relative to those of other
operators, and Mesa's assigned share of field allowables was reduced beginning
in October 1991.
 
     Due to Mesa's reduced share of the field allowable, Mesa's Hugoton
production was 55 Bcfe in 1992 compared to 72 Bcfe in 1991. Mesa's 1993
production from the Hugoton field is estimated to be approximately 56 Bcfe.
Further increases are expected in future years with Mesa's allowable share
returning to higher levels as other operators in the field produce their
shortfalls relative to Mesa's past production. However, Mesa has no control over
production practices of other Hugoton operators and it cannot predict with
certainty the extent or timing of the expected increases.
 
     The KCC held hearings from August 1992 to September 1993 to consider
regulatory changes to the manner in which fieldwide allowables are allocated
among individual wells within the Hugoton field. Specifically, the KCC
considered proposals from various producer groups to amend calculations of well
deliverability, the allocation of allowables based on acreage and infill wells,
and the makeup of underages from prior periods. On December 3, 1993, the KCC
held an administrative conference to announce its findings and recommendations.
Mesa expects the KCC to issue an order implementing the changes in the first
quarter of 1994. Generally, Mesa expects the changes to increase the allowables
assigned to its wells, thus increasing its allowed production. However, it is
unclear at present when the new guidelines will become effective. If the rules
are revised as announced by the KCC and implemented as Mesa expects, Mesa
estimates that it will be permitted to produce an aggregate of an additional 15
to 20 Bcf over the three year period after implementation.
 
     INFILL DRILLING. In 1986, the KCC approved the drilling of a second
(infill) well on each 480-acre or larger spacing unit in the Hugoton field,
beginning January 1, 1987. During each calendar year, producers were permitted
to drill up to 25% of the total number of infill wells for which they qualify.
From January 1, 1987 through December 31, 1993, Mesa participated in 382 infill
wells, essentially completing its infill drilling program related to properties
it operates. Mesa anticipates participating in approximately 19 additional
infill wells, principally on properties not operated by Mesa. Pressures and
deliverabilities measured in the infill wells exceed such amounts in the
original wells. Well performance data indicates that, as a result of infill
drilling, significant reserves will be added to those reflected as proved
reserves in the estimates of DeGolyer and MacNaughton, independent petroleum
engineering consultants ("D&M"), set forth under "-- Reserves." In addition to
the Hugoton infill drilling program, Mesa has invested approximately $26 million
in Hugoton compression and pumping unit facilities and pipeline interconnects
since 1989 to increase production capacity and marketing flexibility.
 
     HUGOTON GAS SALES. Mesa's Hugoton production is sold at market prices. A
substantial portion of Mesa's Hugoton field production is subject to gas
purchase contracts with Western Resources, Inc. ("WRI"), formerly The Kansas
Power and Light Company, and Williams Natural Gas Company ("Williams").
 
     Mesa entered into two gas contracts with WRI effective January 1, 1990. The
WRI contracts expire in May 1995 and provide, among other things, for seasonal
take requirements at market prices and a release for sale to other parties of
gas not nominated for purchase by WRI. The contracts provide for annual
purchases by WRI of 34.0 Bcf of gas in 1993, 37.5 Bcf in 1994 and 19.9 Bcf
during the first five months of 1995. These annual contract quantities are
subject to various seasonal requirements. Under the contracts, WRI pays market
prices as determined monthly based on a price index published by a third party.
The average price received for gas sold to WRI during the year ended December
31, 1992 was $1.56 per Mcf, on a volume of 25.3 Bcf. The average price for the
first nine months of 1993 was $1.86 per Mcf, on a volume of 22.2 Bcf.
 
     Mesa also entered into a gas purchase contract with Williams effective as
of December 1, 1989. Under the contract, Williams has the right to purchase
certain volumes of natural gas produced during each winter season (November
through March) from that portion of the Hugoton field that is connected to the
Williams pipeline system. The Williams contract is for a term equal to the life
of the leases for the properties covered by the contract. Under the contract,
Williams has the right to purchase, during each winter season, a volume of gas
up to 50% (or after the 1994-95 winter season, 60%) of the lesser of (i) the
applicable allowable established by the KCC for the properties covered by the
contract or (ii) the deliverability of such properties. All natural gas produced
from such properties that is not nominated for purchase by Williams is released
for
 
                                       30
<PAGE>   33
 
sale by Mesa to third parties. Williams will pay market prices for natural gas
nominated and taken by it. Williams has not exercised its right to purchase gas
pursuant to this agreement in previous years, thus releasing such volumes for
sale to other parties.
 
     Historically, approximately one-half of Mesa's Hugoton production has been
processed through the Ulysses gas processing plant (which has a capacity of 160
MMcf of natural gas per day) for the extraction of natural gas liquids.
Beginning in 1990, approximately 60% of the remaining Hugoton production was
processed at a plant owned by a third party. Mesa began construction of the new
Satanta Plant in August 1992. The Satanta Plant has the capacity to process 250
MMcf of natural gas per day, enabling Mesa to extract natural gas liquids from
up to 85% of its Hugoton field properties. The Satanta Plant also has the
ability to extract helium from the gas stream. The Satanta Plant was completed
in the third quarter of 1993 at a cost of approximately $43 million. In December
1993, the Satanta Plant averaged 225 MMcf per day of inlet gas, 11,000 Bbl per
day of natural gas liquids production and 430 Mcf per day of crude helium
production.
 
  West Panhandle Field
 
     Mesa, through MOC, has substantial natural gas reserves in the West
Panhandle field in Texas. As of December 31, 1992, these properties represented
approximately 32% of Mesa's total equivalent proved reserves, and approximately
29% of the present value of estimated future net revenues before income taxes.
Production from the West Panhandle field accounted for approximately 39%, 36%
and 24% of Mesa's revenue from the combined sales of natural gas, natural gas
liquids and oil for the years ended December 31, 1992, 1991 and 1990,
respectively. The increase in 1991 and 1992 is attributable to (i) higher sales
volumes, (ii) the recording of revenues for which cash has not yet been received
under a contractual gas balancing arrangement and (iii) the decline in revenues
from other areas due to property sales and reduced Hugoton production. See "Gas
Balancing Sales" below.
 
     Mesa's West Panhandle reserves and production are owned and controlled
pursuant to a contract with CIG originally executed in 1928 by predecessors of
both companies, and which has been amended and supplemented many times,
including the PAA effective as of January 1, 1991 and an amendment to the PAA
effective as of January 1, 1993 (collectively, the "B" Contract). Under the "B"
Contract and associated agreements Mesa operates the wells and production
equipment and has the right to sell gas production from the West Panhandle field
to its customers, without any geographical restrictions. CIG performs certain
administrative functions and owns and operates the gathering system by which
Mesa's production is transported to its Fain natural gas processing plant (the
"Fain Plant"). Each party reimburses the other for certain costs and expenses
incurred for the joint account.
 
     Pursuant to the "B" Contract, Mesa's share of wet gas production from the
field (i.e. gas produced at the wellhead before processing and before reduction
for royalties) is limited to 35 Bcf for 1993 and 32 Bcf per year for 1994
through 1996. Beginning January 1, 1997 and thereafter, Mesa will be entitled to
take all wet gas production during the winter months (November through March).
Also, beginning January 1, 1997, Mesa will be entitled to take all wet gas
production during the summer months (April through October) in excess of the
following CIG daily and seasonal entitlement: 1997-1999 (40 MMcf per day; 8.5
Bcf annually), 2000 (35 to 40 MMcf per day; 7.56 Bcf annually), 2001 and
thereafter until CIG produces its 23% share of ultimate production (35 MMcf per
day; 7 Bcf annually).
 
     Notwithstanding the above winter and summer entitlement, Mesa is entitled
to produce and sell 77% of the ultimate wet gas production from the properties
and CIG is entitled to 23%. Mesa is further limited to a daily wet gas
production of 120 MMcf. In 1993, Mesa's production totaled approximately 35 Bcf
of wet gas.
 
     NATURAL GAS LIQUIDS EXTRACTION. Wet gas produced from the West Panhandle
field contains an average of 1,175 MMBtu per Mcf (compared to typical content of
1,000 MMBtu per Mcf of gas). Therefore, Mesa's share of production taken is
processed through the Fain Plant to extract natural gas liquids.
 
     Mesa has recently completed an expansion of the Fain Plant to increase its
inlet capacity from 90 MMcf per day to 120 MMcf per day. The Fain Plant now has
the daily capacity to produce 11,400 barrels per day of natural gas liquids and
is capable of extracting up to 480 Mcf per day of crude helium.
 
     Mesa, Mid-American Pipeline and MAPCO Natural Gas Liquids Inc. ("MAPCO")
have entered into a new transportation and fractionation agreement effective
December 1, 1993 with respect to the Satanta Plant
 
                                       31
<PAGE>   34
 
and effective April 1, 1994 with respect to the Fain Plant. The agreement has a
term of 7 years and reduces the fee MAPCO charges Mesa to transport and
fractionate natural gas liquids at MAPCO's Conway, Kansas facility.
 
     WEST PANHANDLE GAS SALES CONTRACTS. Natural gas that has been processed at
the Fain Plant (residue or dry gas) is sold to the local gas distribution
utility that serves residential and commercial customers in and around Amarillo
and to a number of industrial customers in the Amarillo area.
 
     Approximately 10 Bcf per year of residue gas is sold to the local utility
under the terms of a long-term contract in existence since 1949, as periodically
amended and supplemented. The contract specified a pricing formula which
resulted in a price per Mcf of $2.71 in 1990, $2.76 in 1991 and $2.81 in 1992
for these volumes.
 
     In mid-1992, Mesa and the local utility entered into a pricing amendment
for the five-year period 1993-1997. Beginning in 1993, 70% of volumes sold to
the utility under this contract are being sold at fixed prices beginning at
$2.71 per Mcf in 1993 and escalating at 5% per annum in 1994 and 1995 and then
at 7 1/2% per annum in 1996 and 1997. The other 30% of volumes under this
contract are being sold at a regional market index price based on spot prices
plus $.10 per Mcf. Prices for 1998 and beyond will be determined by
renegotiation. The average price received for the first nine months of 1993 was
$2.50 per Mcf.
 
     Mesa's principal industrial customer of West Panhandle field gas production
is an intrastate pipeline company which serves an electric power generation
facility. In 1990, Mesa entered into a five-year contract with the pipeline to
supply gas to the electric power facility. This contract provides for minimum
annual volumes of 7 Bcf in 1993, 8.4 Bcf in 1994 and 8.4 Bcf in 1995 at fixed
prices per MMBtu of $1.64, $1.71 and $1.79 for the respective years. Mesa has
historically made sales to the pipeline for the electric power customer in
excess of the minimum volumes specified in the contract at prices negotiated
each month. In 1992, Mesa sold 7.5 Bcf to the pipeline for an average price of
$1.52 per Mcf. Sales to the pipeline in the first nine months of 1993 totaled
9.1 Bcf for an average price of $1.59 per Mcf.
 
     Other industrial customers in the Amarillo area purchase natural gas from
Mesa under short to intermediate term contracts. These sales totaled
approximately 5.1 Bcf in 1992 and 3.7 Bcf in the first nine months of 1993. Mesa
intends to continue to seek new customers in the area for additional West
Panhandle field gas production.
 
     GAS BALANCING SALES. The West Panhandle field's current annual production
allowable is approximately 53 Bcf of wet gas production. CIG is entitled to sell
to its customers gas not sold by Mesa, subject to the gas balancing provisions
included in the PAA. To the extent CIG currently takes production in excess of
its 23% share, Mesa retains a right to take more than its 77% share in future
years to balance.
 
     Mesa records 77% of total "B" Contract production as revenues. The
difference between Mesa's 77% entitlement and the amount of production actually
sold by Mesa to its customers is recorded monthly as revenue from the production
and sale of hydrocarbons with corresponding accruals for operating costs,
production taxes, depreciation, depletion and amortization and gas balancing
receivables. At September 30, 1993, a long-term gas balancing receivable
relating to the "B" Contract of $32.4 million was recorded in Mesa's balance
sheet in other assets.
 
  Other Properties
 
     Mesa's other producing areas at December 31, 1992, which together comprised
less than 5% of Mesa's reserves at such date, were the Gulf Coast and the Rocky
Mountain area. Because of the short life and high productivity of these
properties, they accounted for approximately 15% of Mesa's 1992 total oil and
gas production.
 
     Mesa has working interests in a number of offshore blocks on which 3-D
seismic either has been shot and with respect to which Mesa personnel are
currently evaluating reserve potential, or on which Mesa is in the process of
acquiring 3-D seismic to evaluate potential reserve addition opportunities. It
is possible that if reserves are discovered, they can be recovered through
existing production facilities, thus significantly reducing development costs
and accelerating the time at which production status can be realized.
 
                                       32
<PAGE>   35
 
     A portion of Mesa's interests in the Hugoton field is held by its working
interest in properties subject to the Mesa Royalty Trust. A portion of Mesa's
working interests in the Gulf Coast properties is subject to the Mesa Offshore
Trust.
 
     In the second quarter of 1993, Mesa entered into two separate agreements to
sell oil and gas properties in the Rocky Mountain and Hugoton regions (see Note
5 to Mesa's Consolidated Financial Statements for the nine months ended
September 30, 1993 included elsewhere in this Prospectus). The first sale,
totaling $6.5 million, closed on April 30, 1993. The second sale, totaling $19
million, closed on June 24, 1993. The proceeds were used to supplement available
cash.
 
     Mesa's non-oil and gas tangible properties consist of certain buildings and
equipment located primarily in Amarillo and Dallas, Texas and certain other
items including automobiles and aircraft. Non-oil and gas tangible properties
comprise less than 5% of Mesa's net property costs.
 
THE NGV BUSINESS
 
     Background of Mesa's Involvement in the Industry. Mesa believes that the
NGV market will develop and expand significantly in the 1990s, particularly in
light of (i) the provisions of the recently enacted National Energy Policy Act
of 1992, (ii) the provisions of the amendments to the 1990 Federal Clean Air Act
which require the use of alternative fuels by certain motor vehicle fleets,
(iii) the requirements of numerous state and municipal environmental
regulations, (iv) generally increased awareness of the adverse environmental and
pollution effects of crude oil based motor fuels and (v) the development of more
efficient equipment to convert gasoline and diesel burning vehicles to operate
on natural gas.
 
     In September 1991, Mesa purchased a 70% interest in CleanFuels Inc.
("CleanFuels"), a Martinsburg, West Virginia company focused on the development
and sales of vehicle conversion equipment for NGVs and the installation of
vehicle conversion equipment. In March 1992, Mesa established Mesa Environmental
to own its investment in CleanFuels and to expand Mesa's involvement to all
aspects of the emerging NGV industry. Shortly after its inception, Mesa
Environmental purchased the remaining 30% of CleanFuels and relocated the
company to Mesa Environmental's headquarters in Fort Worth, Texas. In November
1992, Mesa Environmental acquired Garretson Equipment Co., Inc. ("Garretson") of
Mt. Pleasant, Iowa, a designer and manufacturer of natural gas and propane fuel
systems for vehicles and stationary engines.
 
     Business Strategy. Mesa Environmental's goal is to become a leading
provider of NGV conversion equipment and fueling services. Mesa Environmental's
present strategy for reaching this goal includes (i) the development,
manufacture and sale of engine-specific, under-the-hood conversion equipment
which meets the most stringent emissions standards; (ii) pursuing opportunities
in selected foreign markets, particularly Mexico, for conversion equipment
sales, fleet conversions and administration of conversion and fueling programs;
and (iii) pursuing developing opportunities in markets for related products such
as fuel tanks, compressor and dispenser systems, as well as expanding the
marketing effort of Garretson products.
 
     As of September 30, 1993, MHLP had invested approximately $12.5 million in
Mesa Environmental (approximately $4 million of which was used to purchase
CleanFuels and Garretson) and expects to continue to fund its overhead and
business development. Mesa Environmental is a start-up business in a newly
developing industry and the ultimate capital investment required to insure its
viability is uncertain. In addition, Mesa cannot predict when, or if, Mesa
Environmental's operations will begin to earn a profit.
 
RESERVES
 
     Proved reserve estimates for the HCLP Hugoton properties and the West
Panhandle field were prepared in accordance with Commission guidelines by D&M.
The reserve estimates for Mesa's deep Hugoton (non-HCLP), Gulf Coast and Rocky
Mountain properties were prepared by Mesa's engineers, also in accordance with
Commission guidelines. The D&M estimates represent approximately 95% of the
total proved reserves. The summary report prepared by Mesa is filed as an
exhibit to the Registration Statement of which this Prospectus is a part and is
incorporated by reference herein.
 
                                       33
<PAGE>   36
 
     The following table summarizes the estimated proved reserves and estimated
future cash flows associated with Mesa's oil and gas properties as of December
31, 1992 (dollar amounts in thousands):
 
<TABLE>
        <S>                                                                <C>
        Proved reserves:
           Natural gas (MMcf).............................................  1,276,049
           Natural gas liquids, oil and condensate (MBbls)................     87,392
        Future cash inflows..............................................  $3,802,614
        Operating costs..................................................   (828,505)
        Production and ad valorem taxes..................................   (443,294)
        Development and abandonment costs................................   (122,860)
        Future income taxes..............................................   (302,492)
                                                                           ----------
          Future net cash flows..........................................  $2,105,463
                                                                           ----------
                                                                           ----------
        Present value of future net cash flows discounted at 10%
          ("NPV")........................................................  $1,037,181
                                                                           ----------
                                                                           ----------
        NPV before income taxes..........................................  $1,167,694
                                                                           ----------
                                                                           ----------
</TABLE>
 
     In accordance with Commission guidelines, future prices for natural gas
were based on market prices as of December 31, 1992 without future escalation
and, where applicable, contract terms (including fixed and determinable price
escalations under existing contracts). Market prices as of December 31, 1992
were used for future sales of oil, condensate and natural gas liquids. Future
operating costs, production and ad valorem taxes and capital costs were based on
current costs as of year-end 1992, with no escalation.
 
     Over 70% of Mesa's equivalent proved reserves at December 31, 1992 are
natural gas. The natural gas prices in effect at December 31, 1992 (having a
weighted average of $1.94 per Mcf) may not be the most appropriate or
representative prices to use for estimating the value of the reserves since such
prices were influenced by the seasonal demand for natural gas. The average price
received by Mesa for sales of natural gas in 1992 was $1.66 per Mcf. Assuming
all other variables used in the calculation of reserve data are held constant,
Mesa estimates that each $.10 change in the average sales price per Mcf for
natural gas production would affect Mesa's estimated future net cash flows and
present value thereof, before income taxes, by $115 million and $54 million,
respectively.
 
     Mesa's internal estimates of proved reserves for the Hugoton and West
Panhandle areas exceed those of D&M by approximately 25%, or about 450 Bcfe. The
difference is primarily attributable to different estimates of the reserves that
will ultimately be recovered as a result of the Hugoton infill drilling program.
 
     There are numerous uncertainties inherent in estimating quantities of
proved reserves and in projecting the future rates of production and timing of
development expenditures. Reserve data represent estimates only and should not
be construed as being exact. Moreover, the discounted future net cash flows
should not be construed as the current market value of the proved oil and gas
reserves or the costs that would be incurred to obtain equivalent reserves. A
market value determination would include many additional factors including (i)
anticipated future changes in oil and gas prices, production and development
costs; (ii) an allowance for return on investment; (iii) the value of additional
reserves, not considered proved at present, which may be recovered as a result
of further exploration and development activities; and (iv) other business
risks.
 
     During 1992, Mesa filed Form EIA-23, which includes those reserve estimates
prepared by D&M and Mesa as described above, with the Energy Information
Administration of the Department of Energy ("EIA"). Such reserve estimates did
not vary from those estimates contained herein by more than five percent.
 
     The estimated quantities of proved oil and gas reserves, the standardized
measure of future net cash flows from proved oil and gas reserves, and the
changes in the standardized measure of future net cash flows from proved oil and
gas reserves for each of the three years in the period ended December 31, 1992,
appears in Supplemental Financial Data, which is set forth as part of the
Consolidated Financial Statements of the Company and the related notes thereto
set forth elsewhere in this Prospectus.
 
NATURAL GAS SALES
 
     Mesa sells its natural gas production under both short (spot market) and
long-term gas sales contracts. Substantially all of Mesa's gas sales are made at
market prices, with the exception of West Panhandle field volumes that are sold
to a utility under an arrangement that provided for fixed prices in 1992 and,
beginning in 1993, fixed prices for 70% of those volumes and certain other
volumes sold to industrial customers in the Amarillo area. See
" -- Properties -- West Panhandle Field."
 
                                       34
<PAGE>   37
 
PRODUCTION AND PRICES
 
     Allowable production for Mesa's properties is regulated by various state
agencies. Over 71% of Mesa's 1992 production was natural gas. Due to the
seasonal nature of the demand for natural gas, gas production from Mesa's
properties and sales price varies on a seasonal basis. Production volumes and
prices are generally higher during the first and fourth quarters of each
calendar year.
 
     The following table summarizes Mesa's oil and gas production, average sales
prices and average production costs:
 
<TABLE>
<CAPTION>
                                       NINE MONTHS
                                          ENDED
                                      SEPTEMBER 30                 YEAR ENDED DECEMBER 31
                                     ---------------   ----------------------------------------------
                                      1993     1992     1992     1991      1990      1989      1988
                                     ------   ------   ------   -------   -------   -------   -------
<S>                                  <C>      <C>      <C>      <C>       <C>       <C>       <C>
Production:
  Natural gas (MMcf)................ 58,082   63,254   89,527   108,522   137,333   137,167   116,414
  Natural gas liquids (MBbls).......  3,341    3,453    4,840     4,725     3,753     3,225     3,304
  Oil and condensate (MBbls)........    496      752      984       767     1,480     2,984     2,975
Average price*:
  Natural gas (per Mcf)............. $ 1.76   $ 1.59   $ 1.72   $  1.54   $  1.61   $  1.65   $  1.79
  Natural gas liquids (per Bbl).....  13.06    11.84    12.32     13.07     14.57      9.71      9.28
  Oil and condensate (per Bbl)......  17.49    18.83    18.86     20.23     22.28     17.23     14.56
Average production cost per Mcfe.... $  .66   $  .50   $  .50   $   .47   $   .51   $   .53   $   .50
</TABLE>
 
- ---------------
 
* The average natural gas price for the nine months ended September 30, 1993 and
  1992 and the years ended December 31, 1992, 1991 and 1990 reflects $(.01) per
  Mcf, $.10 per Mcf, $.06 per Mcf, $.08 per Mcf and $(.01) per Mcf,
  respectively, related to hedges of natural gas production in the natural gas
  futures market.
 
PRODUCING ACREAGE AND WELLS; UNDEVELOPED ACREAGE
 
     Mesa's ownership of oil and gas acreage held by production, producing wells
and undeveloped oil and gas acreage as of September 30, 1993 is set forth in the
table below.
 
<TABLE>
<CAPTION>
                                                                                 UNDEVELOPED
                                  PRODUCING ACREAGE      PRODUCING WELLS           ACREAGE
                                 -------------------     ----------------     -----------------
                                  GROSS        NET       GROSS      NET       GROSS       NET
                                 -------     -------     -----     ------     ------     ------
    <S>                          <C>         <C>         <C>       <C>        <C>        <C>
    ONSHORE U.S.
      Kansas.................    258,994     231,239     1,294       984.1      4,800      4,800
      North Dakota...........      5,760       4,258        10         3.5      3,771      2,518
      Texas..................    241,353     191,044       587       450.1      5,210      4,593
      Wyoming................     11,715       4,603         6         1.3     17,498     12,297
      Other..................      4,606       2,847         8         1.3     35,373     24,214
                                 -------     -------     -----     -------     ------     ------
         Total Onshore.......    522,428     433,991     1,905     1,440.3     66,652     48,422
                                 -------     -------     -----     -------     ------     ------
    OFFSHORE U.S.
      Louisiana..............     88,274      46,022        77        32.5          0          0
      Texas..................     73,808      15,233        46         7.6          0          0
                                 -------     -------     -----     -------     ------     ------
         Total Offshore......    162,082      61,255       123        40.1     66,652     48,422
                                 -------     -------     -----     -------     ------     ------
      Grand Total............    684,510     495,246     2,028     1,480.4     66,652     48,422
                                 -------     -------     -----     -------     ------     ------
                                 -------     -------     -----     -------     ------     ------
</TABLE>
 
     The total onshore and offshore producing wells shown above consist of 1,966
gross (1,461.9 net) gas wells and 62 gross (18.4 net) oil wells in the United
States.
 
     In June 1992, Mesa sold its 12.5 percent gross overriding royalty interest
in approximately 290,000 undeveloped and 234,000 producing acres in Canada. At
September 30, 1993, Mesa also owned royalty interests in approximately 41,743
non-producing and 77,066 producing net acres of minerals in the United States.
 
                                       35
<PAGE>   38
 
DRILLING ACTIVITIES
 
     The following table sets forth Mesa's drilling activity for each of the six
years in the six year period ended December 31, 1993, including the number of
net exploratory and development productive and dry wells drilled. At December
31, 1993, Mesa was not participating in the drilling of any wells.
 
<TABLE>
<CAPTION>
                         1993             1992             1991             1990              1989             1988
                     ------------     ------------     ------------     -------------     ------------     ------------
                     GROSS   NET      GROSS   NET      GROSS   NET      GROSS    NET      GROSS   NET      GROSS   NET
                     -----   ----     -----   ----     -----   ----     -----   -----     -----   ----     -----   ----
<S>                  <C>     <C>      <C>     <C>      <C>     <C>      <C>     <C>       <C>     <C>      <C>     <C>
EXPLORATORY WELLS
  Productive.....       --     --         5    4.1         6    4.7        --      --         5    1.6        --     --
  Dry............        1    1.0         1     .4         1     .2         5     3.1         5    2.6        --     --
DEVELOPMENT WELLS
  Productive.....       43   28.9        22   16.5        26   10.9       146   120.8       151   88.6       133   91.9
  Dry............       --     --        --     --        --     --        --      --         2     .2         3     .3
                     -----   ----     -----   ----     -----   ----     -----   -----     -----   ----     -----   ----
Total............       44   29.9        28   21.0        33   15.8(1)    151   123.9(1)    163   93.0       136   92.2
                     -----   ----     -----   ----     -----   ----     -----   -----     -----   ----     -----   ----
                     -----   ----     -----   ----     -----   ----     -----   -----     -----   ----     -----   ----
</TABLE>
 
- ---------------
 
(1) The decrease in drilling activity after 1990 reflects the completion of
    Mesa's infill drilling program in the Hugoton field.
 
INVESTMENT ACTIVITIES
 
     Mesa invests from time to time in marketable equity and other securities of
other companies and in commodity and futures contracts, primarily related to
crude oil and natural gas. Mesa also enters into natural gas futures contracts
as a hedge against natural gas price fluctuations.
 
OPERATING HAZARDS AND UNINSURED RISKS
 
     Mesa's oil and gas activities are subject to all of the risks normally
incident to exploration for and production of oil and gas, including blowouts,
cratering and fires, each of which could result in damage to life and property.
Offshore operations are subject to a variety of operating risks, such as
hurricanes and other adverse weather conditions and lack of access to existing
pipelines or other means of transporting production. Furthermore, offshore oil
and gas operations are subject to extensive governmental regulations, including
certain regulations that may, in certain circumstances, impose absolute
liability for pollution damages, and to interruption or termination by
governmental authorities based on environmental or other considerations. In
accordance with customary industry practices, Mesa carries insurance against
some, but not all, of these risks. Losses and liabilities resulting from such
events would reduce revenues and increase costs to Mesa to the extent not
covered by insurance.
 
COMPETITION
 
     The oil and gas business is highly competitive in the search for,
acquisition of and sales of oil and gas. Mesa's competitors in these endeavors
include the major oil and gas companies, independent oil and gas concerns, and
individual producers and operators, as well as major pipeline companies, many of
which have financial resources greatly in excess of those of Mesa. Mesa believes
that its competitive position is affected by, among other things, price,
contract terms and quality of service.
 
     Mesa is one of the largest owners of natural gas reserves in the United
States. Mesa's major gas sales contracts (See "Business-Properties") allow
production not sold to the contract purchaser to be sold to other purchasers in
the spot market. Production from Mesa's properties has access to a substantial
portion of the major metropolitan markets in the United States through numerous
pipelines and other purchasers. Mesa is not dependent upon any single purchaser
or small group of purchasers.
 
     Mesa believes that its competitive position is enhanced by its substantial
long life reserve holdings and related deliverabilities, its flexibility to sell
such reserves in a diverse number of markets at competitive prices and its
ability to produce its reserves at a low cost.
 
                                       36
<PAGE>   39
 
LEGAL PROCEEDINGS
 
  Unocal Lawsuit
 
     For a discussion of the Unocal lawsuit and the pending settlement thereof,
see "Unocal Litigation and Settlement" and "Management's Discussion and Analysis
of Financial Condition and Results of Operations."
 
  Preference Unitholders
 
     The Company and Mr. Pickens are defendants in lawsuits related to the
Corporate Conversion, styled Odmark, et al. v. Mesa Limited Partnership, et al.,
Gerardo, et al. v. Mesa Limited Partnership, et al., and McBride Trust, et al.
v. Mesa Limited Partnership, et al., pending in the U.S. District Court for the
Northern District of Texas-Dallas Division. The first two lawsuits have been
certified as class actions and the third is an individual action by or on behalf
of former holders of preference units of the Partnership. All three allege
substantially the same claims under the federal securities laws and common law.
Plaintiffs allege, among other things, that (i) the proxy materials delivered to
unitholders in connection with the Corporate Conversion contained material
misstatements and omissions, (ii) the general partners of the Partnership
breached fiduciary duties to the preference unitholders in structuring the
transaction and allocating the common stock of the Company and (iii) the
Corporate Conversion was not properly approved by the unitholders of the
Partnership because certain procedural requirements of the partnership agreement
were allegedly not met. The Company and the other defendants have denied the
allegations and believe they are without merit. Plaintiffs seek an order
requiring payment to the former preference unitholders of $164 million in
respect of the preferential distribution rights of their units, a declaration
declaring the Corporate Conversion void and rescinding it, unspecified
compensatory and punitive damages and other relief. Discovery has commenced.
 
     The Company and the other defendants have denied the plaintiffs'
allegations. Several lawsuits making allegations substantially the same as those
referenced in clauses (i) and (ii) above were filed by preference unitholders in
Delaware Chancery Court in 1991 following the proposal of the Corporate
Conversion. In December 1991, the Chancery Court denied the plaintiffs' request
for a preliminary injunction to enjoin consummation of the Corporate Conversion.
In August 1992, the Chancery Court granted a motion by the plaintiffs to dismiss
the Delaware lawsuits and awarded attorneys' fees to plaintiffs' counsel.
 
  Masterson Lawsuit
 
     In 1986, MOLP acquired rights in certain properties located in the West
Panhandle field of Texas when it acquired the assets of Pioneer Corporation. In
particular, MOLP acquired an interest in gas production from an oil and gas
lease (the "Gas Lease") dated April 30, 1955, between R. B. Masterson, et al.,
as lessor, and CIG, as lessee.
 
     In February 1992, the current lessors of the Gas Lease sued CIG in Federal
District Court in Amarillo, Texas, claiming that CIG had underpaid royalties due
under the Gas Lease. The plaintiffs alleged that the underpayment was the result
of CIG's using an improper gas sales price upon which to calculate royalties,
and that the proper price should have been determined pursuant to a pricing
clause in a July 1, 1967 amendment to the Gas Lease. The complaint did not
specify the damages sought and appeared to relate only to royalties for periods
after October 1, 1988. The plaintiffs also sought a declaration by the court as
to the proper price to be used for calculating future royalties.
 
     In August 1992, CIG filed a third party complaint against MOLP for any such
royalty underpayments which may be allocable to MOLP's interest in the Gas
Lease.
 
     On December 22, 1992, the plaintiffs filed a Second Amended Complaint,
including both CIG and MOLP as defendants, again alleging that the use of an
erroneous price in calculating royalties resulted in underpayments of royalties,
but for the first time alleging that the underpayments amounted to approximately
$250 million (including interest) and covered the period July 1, 1967 to
present. MOLP was subsequently dismissed by the plaintiffs for procedural
reasons, but remains in the case as a defendant in CIG's third party complaint.
 
     The plaintiffs have recently filed court papers alleging royalty
underpayments of approximately $450 million (including interest at 10%) covering
the period July 1, 1967 to the present. In addition, the plaintiffs
 
                                       37
<PAGE>   40
 
seek exemplary damages. Management believes that MOLP has several defenses to
plaintiffs' claims, including (i) that the royalties for all periods were
properly computed and paid and (ii) that plaintiffs' claims with respect to all
periods prior to October 1, 1988 (which appear to account for the large majority
of the claims) were explicitly released by a 1988 written agreement among
plaintiffs, CIG and MOLP and are further barred by the statute of limitations.
If the plaintiffs were to prevail, the manner in which any resulting liability
would be shared between MOLP and CIG would depend on the resolution of issues
relating to the contractual agreements and the relationship between MOLP, CIG
and the lessors during the period in question. No trial date has been set.
 
                             REGULATION AND PRICES
 
     Mesa'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 affected by
price control, tax, conservation, environmental and other laws relating to the
petroleum industry, by changes in such laws and by constantly changing
administrative regulations.
 
NATURAL GAS REGULATIONS
 
     Until January 1, 1993, Mesa was subject to direct federal regulation by the
FERC with respect to certain of its sales of natural gas. The principal impact
of these regulations historically was the regulation of prices received for
natural gas produced and sold for resale in interstate commerce in the United
States. In addition, the approval of the FERC was required for both the
commencement and the abandonment of certain interstate gas sales.
 
     The transportation and the sale for resale of natural gas in interstate
commerce have been regulated pursuant to the Natural Gas Act of 1938 (the
"NGA"). However, beginning in late 1978, the maximum selling prices of certain
categories of gas sold by entities such as Mesa, whether sold in interstate or
intrastate commerce, were regulated as "first sales" pursuant to the Natural Gas
Policy Act of 1978 (the "NGPA"). Both of these statutes are administered by the
FERC and have had direct application to producer sales like those made by Mesa.
On July 26, 1989, the Natural Gas Wellhead Decontrol Act of 1989 (the "Decontrol
Act") was enacted. The Decontrol Act removed, as of January 1, 1993, all
remaining federal price controls from natural gas sold in "first sales" and
eliminated any requirement to secure FERC approval for the commencement and
abandonment of interstate gas sales.
 
     Historically, interstate pipeline companies have generally acted as
wholesale merchants by purchasing natural gas from producers and reselling the
gas to other interstate pipelines, local distribution companies and large
end-users. Under the NGA and NGPA, the transportation and sale of natural gas by
interstate pipeline companies have been and continue to be subject to extensive
regulation, and the construction of new pipelines, the extension of existing
pipelines and the commencement and cessation of sales or transportation services
by pipeline companies generally require prior FERC authorization.
 
     Commencing in 1985, the FERC promulgated a series of orders and regulations
adopting changes that significantly affect the transportation and marketing of
natural gas. These changes were intended to foster competition in the natural
gas industry by, among other things, inducing or mandating that interstate
pipeline companies provide nondiscriminatory transportation services to
producers, distributors and other shippers ("open access" requirements). These
changes commenced with FERC Order 436 and continued with FERC Orders 500 and
500-I.
 
     In October 1985, FERC Order 436 allowed pipelines to apply for one-time
authorization to provide open-access transportation to anyone seeking such
service. FERC's stated goal by such action was to create and enhance competition
in natural gas markets by requiring that access to the interstate transportation
facilities necessary to reach all markets be provided on an open and
nondiscriminatory basis. Order 436 was vacated by the courts and replaced by an
interim rule, Order 500, which readopted the majority of Order 436 with changes
to respond to the problems which the court found with Order 436. One principal
problem was the resolution of liabilities incurred by open access pipelines
under existing take or pay contracts with their historic producer suppliers.
Among other things, Order 500 provided to the interstate pipelines a crediting
mechanism to assist them in dealing with these take or pay obligations. The
final rule was issued as Order 500-H on
 
                                       38
<PAGE>   41
 
December 13, 1989. Order 500-H was generally upheld by the United States Court
of Appeals on August 24, 1990, although certain portions were remanded to the
FERC for further consideration. These remaining issues, concerning pregranted
abandonment and the use of certain types of passthrough mechanisms by interstate
pipelines to recover take-or-pay costs, are currently being addressed by the
FERC in separate proceedings and will be subject to further appellate review.
Mesa cannot predict what further action the FERC or the federal courts may take
regarding these remaining issues or what impact, if any, such action might have
on Mesa's business.
 
     On April 8, 1992, the FERC issued Order 636 requiring further restructuring
of the sales and transportation services provided by interstate pipeline
companies. Order 636 amended certain existing regulations and adopted certain
new regulations governing all interstate pipelines that perform open access
transportation. The FERC considered the changes necessary to improve the
competitive structure of the interstate natural gas pipeline industry and to
complete the creation of a regulatory framework putting gas sellers into more
direct contractual relations with gas buyers than has historically been the
case. Order 636 reflects the FERC's finding that under the preexisting
regulatory structure, such interstate pipelines and other gas merchants,
including producers, do not compete on an equal basis. The FERC asserts that
Order 636 is designed to equalize that marketplace. This equalization process is
being implemented through negotiated settlements in individual pipeline service
restructuring proceedings, designed specifically to "unbundle" those services
(e.g. transportation, sales and storage) provided by many interstate pipelines
so that producers of natural gas may secure services from the most economical
source, whether interstate pipelines or other parties. In many instances, the
result of the FERC initiatives may be to substantially reduce or bring to an end
the interstate pipelines' traditional role as wholesalers of natural gas in
favor of providing only natural gas storage and transportation services. These
restructuring proceedings resulting from Order 636 have continued throughout
1993, with the vast majority of pipelines having already received FERC orders
approving their compliance filings, subject to various conditions. Thus, the
current 1993-94 winter heating season is the first such period during which the
FERC's Order 636 procedures will be operative.
 
     Although Order 636 does not regulate gas producers such as Mesa, the FERC
has stated that Order 636 is intended to foster increased competition within all
phases of the natural gas industry. It is unclear what impact, if any, increased
competition within the natural gas industry under Order 636 will have on Mesa as
a producer. Furthermore, although the FERC earlier denied a stay of the
effectiveness of Order 636, thus assuring that its requirements will be
implemented, because the requirements of Order 636 are being implemented through
individual restructuring proceedings on a pipeline-by-pipeline basis, it is
impossible to predict what effect Order 636 will have on Mesa and its gas
marketing efforts. In addition, in response to numerous requests that the FERC
grant rehearing of Order 636, on August 3, 1992 and November 27, 1992 the FERC
issued its Orders 636-A and 636-B, which largely confirmed the provisions and
goals previously set forth in Order 636, and otherwise made relatively modest
changes to its prior rule. Numerous petitions seeking judicial review of Orders
636, 636-A and 636-B have been filed. In addition, numerous petitions have been
filed seeking judicial review of FERC's actions in approving, modifying or
denying various proposals put forth in individual pipeline restructuring
proceedings. Because the restructuring requirements that have emerged to date in
the individual pipeline proceedings are in some instances different from those
of Orders 636, 636-A and 636-B as originally promulgated, it is not possible to
predict what effect, if any, the final rules resulting from these many orders
will have on Mesa, although open access transportation as envisioned by these
orders may further enhance Mesa's ability to market gas to a wider variety of
markets than would otherwise be the case.
 
STATE AND OTHER REGULATION
 
     All of the jurisdictions in which Mesa owns producing oil and gas
properties have statutory provisions regulating the production and sale of crude
oil and natural gas. The regulations often require permits for the drilling of
wells but extend also to the spacing of wells, the prevention of waste of oil
and gas resources, the rate of production, prevention and clean-up of pollution
and other matters. In Texas, the Railroad Commission regulates the amount of oil
and gas produced within the state by assigning to each well or proration unit an
allowable rate of production. Certain other jurisdictions, including Kansas,
impose similar restrictions. See "Business -- Properties" for a discussion of
recent changes to Mesa's allowables in the Hugoton field.
 
                                       39
<PAGE>   42
 
     Certain producing states, including Texas, Louisiana and Oklahoma, have
recently adopted or considered adopting measures that alter the methods
previously used to prorate gas production from wells located in these states.
For example, the new Texas rules provide for reliance on information filed
monthly by well operators, in addition to historical production data for the
well during comparable past periods, to arrive at an allowable. This is in
contrast to historic reliance on forecasts of upcoming takes filed monthly by
purchasers of natural gas in formulating allowables, a procedure which resulted
in substantial excess allowables over volumes actually produced. Mesa cannot
predict what ultimate effect the new prorationing regulations will have on its
production of gas or whether other states will adopt similar or other gas
prorationing procedures.
 
     On October 24, 1992, comprehensive national energy legislation was enacted
which focused on electrical power, renewable energy sources and conservation.
The legislation guarantees equal treatment of domestic and imported natural gas
supplies, mandates expanded use of natural gas and other alternative fuels
vehicles, funds natural gas research and development, permits continued offshore
drilling and use of natural gas feedstock for electric generation, and adopts
various conservation measures designed to reduce consumption of imported oil.
Mesa cannot predict what effect, if any, this legislation will have on its
business.
 
FEDERAL ROYALTY MATTERS
 
     By a letter dated May 3, 1993 directed to thousands of producers holding
interests in federal leases, the Interior Department announced its
interpretation of existing federal leases to require the payment of royalties on
past natural gas contract settlements which were entered into in the 1980s and
1990s to resolve, among other things, take-or-pay and minimum take claims by
producers against pipelines and other buyers. The Interior Department's letter
set forth various theories of liability, all founded on the Department's
interpretation of the term "gross proceeds" as used in federal leases and
pertinent federal regulations. In an effort to ascertain the amount of such
potential royalties, the Interior Department sent a letter to producers on June
18, 1993 requiring producers to provide all data on all natural gas contract
settlements, regardless of whether gas produced from federal leases was involved
in the settlement. Mesa received a copy of this information demand letter. In
response to the Interior Department's action, in July of 1993 various industry
associations and others filed suit in the United States District Court for the
Northern District of West Virginia seeking an injunction to prevent the
collection of royalties on natural gas contract settlement amounts under the
Interior Department's theories. The lawsuit has recently been transferred to the
United States District Court in Washington, D.C. Because this lawsuit is pending
and because of the complex nature of the calculations necessary to determine
potential additional royalty liability under the Interior Department's theories,
it is impossible to predict what, if any, additional or different royalty
obligation the Interior Department may assert with respect to any of Mesa's
prior natural gas contract settlements. Likewise, Mesa cannot predict what
effect, if any, the Interior Department's claims will have on it.
 
OTHER
 
     Various federal, state and local laws and regulations regulating the
discharge of materials into the environment or otherwise specifically relating
to the protection of the environment may directly or indirectly affect Mesa's
operations. Mesa is not involved in any administrative or judicial proceedings
arising under federal, state or local environment protection laws and
regulations which would have a material adverse impact on Mesa's financial
position or results of operations.
 
                                       40
<PAGE>   43
 
                                   MANAGEMENT
 
DIRECTORS AND OFFICERS
 
     The following table sets forth the name, age and five-year employment
history of each director and officer of the Company.
 
<TABLE>
<CAPTION>
         NAME AND AGE                     BUSINESS EXPERIENCE OVER PAST FIVE YEARS
- ------------------------------  -------------------------------------------------------------
<S>                             <C>
Boone Pickens, age 65.........  January 1992-Present, Chairman of the Board of Directors and
                                  Chief Executive Officer of the Company; October 1985-December
                                  1991, General Partner of the Partnership; 1964-January
                                  1987, Chairman of the Board of Directors, President and
                                  founder of Original Mesa.
Paul W. Cain, age 55..........  January 1992-Present, Director, President and Chief Operating
                                  Officer of the Company; August 1986-December 1991, President
                                  and Chief Operating Officer of the Partnership; January
                                  1986-August 1986, Executive Vice President of the
                                  Partnership; Director of Bicoastal.
John S. Herrington, age 54....  January 1992-Present, Director of the Company; December 1991-
                                  Present, personal investments and real estate activities;
                                  May 1990-November 1991, Chairman of the Board of Harcourt
                                  Brace Jovanovich, Inc. (publishing); May 1989-May 1990,
                                  Director of Harcourt Brace Jovanovich, Inc.; February
                                  1985-January 1989, Secretary of Energy of the United
                                  States.
Wales H. Madden, Jr., age       
  66..........................  January 1992-Present, Director of the Company; December 1985-
                                  December 1991, Member of the Advisory Committee of the     
                                  Partnership; 1964-January 1987, Director of Original Mesa; 
                                  Self-employed attorney and businessman for more than the   
                                  last five years; Director of Boatman's First National Bank 
                                  of Amarillo and Uniform Printing and Supply of Boston.     
Fayez S. Sarofim, age 65......  January 1992-Present, Director of the Company; Chairman of
                                  the Board and President of Fayez Sarofim & Co. (investment
                                  advisor) for more than the last five years; Director of
                                  Teledyne, Inc., Unitrin, Inc., Argonaut Group, Inc. and
                                  Imperial Holly Corporation.
Robert L. Stillwell, age 57...  January 1992-Present, Director of the Company; December 1985-
                                  December 1991, Member of the Advisory Committee of the
                                  Partnership; 1969-January 1987, Director of Original Mesa;
                                  Partner in the law firm of Baker & Botts, L.L.P., Houston,
                                  Texas, for more than the last five years.
J. R. Walsh, Jr., age 69......  January 1992-Present, Director of the Company; December 1985-
                                  December 1991, Member of the Advisory Committee of the
                                  Partnership; 1982-January 1987, Director of Original Mesa;
                                  President and Chairman of the Board of United Mud Service
                                  Company (oil and gas service company) for more than the
                                  last five years.
Dennis E. Fagerstone, age       
  45..........................  January 1992-Present, Vice President-Exploration and        
                                  Production of the Company; May 1991-December 1991, Vice     
                                  President-Exploration and Production of the Partnership;  
                                  June 1988-May 1991, Vice President-Operations of the      
                                  Partnership; January 1986-June 1988, Manager-Operations of
                                  the Partnership.                                          
S. Leonard Hruzek, Jr., age     
  39..........................  January 1992-Present, Vice President-Marketing and Land of   
                                  the Company; May 1991-December 1991, Vice President-Marketing
                                  of the Partnership; February 1990-May 1991, Vice President 
                                  and Controller of the Partnership; June 1987-February 1990,
                                  Controller of the Partnership.                             
</TABLE>
 
                                       41
<PAGE>   44
 
<TABLE>
<CAPTION>
         NAME AND AGE                     BUSINESS EXPERIENCE OVER PAST FIVE YEARS
- ------------------------------  -------------------------------------------------------------
<S>                             <C>
Andrew J. Littlefair, age       
  33..........................  January 1992-Present, Vice President-Public Affairs of the     
                                  Company; August 1987-December 1991, Assistant to the General   
                                  Partner of the Partnership; January 1984-August 1987, Staff  
                                  Assistant to the President of the United States,             
                                  Washington, D.C.                                             
Charles L. Carpenter, age       
  55..........................  April 1992-Present, General Counsel and Secretary of the     
                                  Company; October 1988-March 1992, Chief Counsel-Marketing of 
                                  Oryx Energy; June 1983-October 1988, Chief Counsel-General 
                                  Legal Services of Oryx Energy.                             
William D. Ballew, age 35.....  January 1992-Present, Controller of the Company; May 1991-
                                  December 1991, Controller of the Partnership; January
                                  1991-May 1991, Manager-Accounting of the Partnership;
                                  December 1988-December 1990, Assistant to the Controller of
                                  the Partnership; July 1986-December 1988, Audit Manager for
                                  Price Waterhouse, Dallas, Texas.
</TABLE>
 
     Each director of the Company who was not also an employee of the Company or
its subsidiaries received compensation of $20,000 in 1993. Directors who are
also employees of the Company receive no remuneration for their services as
Directors.
 
     The Board of Directors of the Company held five meetings in 1993, each of
which was attended by all members. The Board of Directors has the following
standing committees: the Audit Committee, the Compensation Committee and the
Stock Option Committee. It does not have a Nominating Committee.
 
     The Audit Committee is composed of Messrs. Herrington, Madden and Walsh.
Its primary functions are (i) the recommendation of independent public
accountants, (ii) the review of the independence of the independent public
accountants, audit engagement and other professional services of the independent
public accountants, and (iii) provision for the availability to the independent
public accountants of all aspects of the Company's accounting practices and
procedures. The Audit Committee held two meetings in 1993.
 
     The Compensation Committee is composed of Messrs. Sarofim, Stillwell and
Walsh. The Compensation Committee held three meetings in 1993. The Stock Option
Committee, which administers the 1991 Stock Option Plan (the "Option Plan"), is
also composed of Messrs. Sarofim, Stillwell and Walsh. The Stock Option
Committee held three meetings in 1993.
 
     In September 1990, the Company and Mr. Pickens entered into a consent
decree to settle allegations by the Commission that the Company and Mr. Pickens
had violated Sections 17(a)(2) and 17(a)(3) of the Securities Act in connection
with a proposal made by the Company in February 1988 to acquire Homestake Mining
Company. Under the terms of the settlement, without admitting or denying any of
the Commission's allegations, the Company and Mr. Pickens consented to the entry
of a judgment enjoining them from future violations of such sections. The
Commission's allegations related to the Company's February 1988 press release
announcing its offer to acquire Homestake and its subsequent sales of Homestake
shares. The Company deposited $2.3 million in a fund for disbursement to other
persons who purchased Homestake shares at the time of the 1988 offer.
 
LIMITATION OF DIRECTOR LIABILITY
 
     The Articles of Incorporation of the Company contain a provision that
limits the liability of the Company's directors as permitted by the Texas
Business Corporation Act. The provision eliminates the personal liability of
directors to the Company and its shareholders may be unable to recover monetary
damages against directors for negligent or grossly negligent acts or omissions
in violation of their duty of care. The provision does not change the liability
of a director for breach of his duty of loyalty to the Company or to
shareholders, acts or omissions not in good faith or which involve intentional
misconduct or a knowing violation of law, an act or omission for which the
liability of a director is expressly provided for by an applicable statute, or
in respect of any transaction from which a director received an improper
personal benefit. Pursuant to the Articles of Incorporation, the liability of
directors will be further limited or eliminated without action by shareholders
if Texas law is amended to further limit or eliminate the personal liability of
directors.
 
                                       42
<PAGE>   45
 
INDEMNIFICATION ARRANGEMENTS
 
     The Company's Bylaws provide for the indemnification of its executive
officers and directors, and the advancement to them of expenses in connection
with proceedings and claims, to the fullest extent permitted by the Texas
Business Corporation Act. The Company has also entered into indemnification
agreements with its executive officers and directors that contractually provide
for indemnification and expense advancement and include related provisions meant
to facilitate the indemnitees' receipt of such benefits. In addition, the
Company purchased customary directors' and officers' liability insurance
policies for its directors and officers. The Bylaws and agreements with
directors and officers also provide for indemnification for amounts (i) in
respect of the deductibles for such insurance policies, (ii) that exceed the
liability limits of such insurance policies and (iii) that would have been
covered by prior insurance policies of the Company or its predecessors. Such
indemnification may be made even though directors and officers would not
otherwise be entitled to indemnification under other provisions of the Bylaws or
such agreements.
 
BTC PARTNERS
 
     The Company has entered into an agreement with BTC Partners, Inc. ("BTC"),
a Delaware corporation, pursuant to which BTC provides certain financial and
advisory services to the Company. BTC regularly functions as part of Mesa's
management team with respect to financial and other matters. Pursuant to the
agreement, BTC receives an annual retainer and may, in the discretion of the
Company, be paid additional fees for services it renders in connection with
financing transactions, debt restructuring activities, acquisitions or
dispositions of properties or assets and other transactions with respect to
which BTC assists the Company. Such amounts are payable in respect of BTC's
services to the Company in evaluating, negotiating and implementing such
transactions. The agreement also provides that the Company will provide BTC
certain other benefits and support services. The agreement may be terminated at
any time by either the Company or BTC. Employees of BTC devote a substantial
portion of their time to the affairs of the Company, but the arrangement with
BTC allows BTC and its employees to engage in unrelated business activities. The
controlling stockholder of BTC is Sidney Tassin.
 
                                       43
<PAGE>   46
 
                             EXECUTIVE COMPENSATION
 
COMPENSATION OF EXECUTIVE OFFICERS
 
     The table set forth below contains certain information regarding
compensation earned by, awarded to, or paid to the Chief Executive Officer and
the other four most highly compensated executive officers of Mesa for services
rendered to Mesa during the years 1991-1993.
 
                           SUMMARY COMPENSATION TABLE
 
<TABLE>
<CAPTION>
                                                                                              LONG-TERM
                                                                                             COMPENSATION
                                                            ANNUAL COMPENSATION              OPTIONS/SARS
                                                   --------------------------------------      (NO. OF
                NAME AND                                                     OTHER ANNUAL    UNDERLYING      ALL OTHER
          PRINCIPAL POSITIONS             YEAR      SALARY       BONUS       COMPENSATION      SHARES)      COMPENSATION(5)
- ----------------------------------------  ----     --------     --------     ------------    -----------    ------------
<S>                                       <C>      <C>          <C>          <C>             <C>            <C>
Boone Pickens...........................  1993     $675,000     $      0             --(4)     275,000       $  114,750(6)
  Chairman of the                         1992      960,000            0(2)          --        800,000        1,047,707(7)
  Board of Directors                      1991           --(1)        --(3)          --              0               --(17)
  and Chief Executive Officer
Paul W. Cain............................  1993      400,020      225,000             --(4)     100,000          106,253(8)
  President and Chief                     1992      400,020            0(2)          --        150,000          273,040(9)
  Operating Officer                       1991      455,748      200,000             --              0               --(17)
Dennis E. Fagerstone....................  1993      199,980       75,000             --(4)      10,000           46,747(10)
  Vice President -- Exploration           1992      199,980      106,323(2)          --         50,000           72,740(11)
  and Production                          1991      170,225      179,442             --              0               --(17)
S. Leonard Hruzek, Jr...................  1993      150,000       50,000             --(4)           0           34,000(12)
  Vice President-- Marketing              1992      150,000       99,089(2)          --         40,000           58,892(13)
  and Land                                1991      135,245      131,141             --              0               --(17)
Andrew J. Littlefair....................  1993      115,980       75,000             --(4)      25,000           32,467(14)
  Vice President -- Public Affairs        1992      109,980       92,330(2)          --         30,000           47,583(15)
                                          1991(16)       --           --             --             --               --(17)
</TABLE>
 
- ---------------
 
 (1) As General Partner of the Partnership, Mr. Pickens was not entitled to an
     annual salary. The Partnership Agreement of the Partnership provided that
     the General Partner was entitled to receive a management fee in an
     aggregate amount equal to 1% of the cash distributions to holders of units
     of the Partnership, but not to exceed 1% of the annual cash distributions
     per common unit multiplied by 90,000,000. No distributions on the common
     units were made in 1991. Accordingly, the General Partner did not receive a
     management fee for 1991. The Partnership Agreement also provided that the
     General Partner was entitled to receive an acquisition fee, payable in
     cash, in connection with the acquisition of certain properties and assets
     by the Partnership and a securities gain fee on certain gains realized by
     the Partnership on certain investments, including the purchase and sale of
     marketable securities and futures contracts. The General Partner received a
     fee of $373,853 in 1991.
 
 (2) Bonuses paid to the executive officers of Mesa in 1992 include bonus
     payments with respect to performance in 1992 as well as the unpaid portion
     of deferred bonuses awarded in 1990 and 1991. The following amounts were
     paid to the executive officers of Mesa for services rendered during 1992:
     $0 to Mr. Pickens; $0 to Mr. Cain; $28,000 to Mr. Fagerstone; $25,000 to
     Mr. Hruzek; and $32,000 to Mr. Littlefair. The balance of the 1992 Bonus
     column amounts represent the acceleration of the deferred portion of
     bonuses for prior years that were paid to each individual in the above
     table in connection with the cancellation of employee life insurance
     policies on July 1, 1992 (see discussion under "Bonus Plan" and "Key
     Employee Life Insurance" below.)
 
 (3) Mr. Pickens did not participate in Mesa's bonus plan (see separate
     discussion below under "Bonus Plan") while serving as General Partner of
     the Partnership.
 
 (4) Apart from the compensation set forth in the summary compensation table and
     under the plans and pursuant to the transactions described below, other
     compensation paid for services during the year ended December 31, 1993, to
     each individual named in the summary compensation table aggregated less
     than 10% of the total salary and bonus reported for such individual in the
     summary compensation table, or $50,000, if lower.
 
                                       44
<PAGE>   47
 
 (5) Except as reflected in other notes, "All Other Compensation" consists
     principally of three items. First, Mesa maintains an Employees Premium Plan
     and a Profit Sharing Plan, both of which are retirement plans (the
     "Retirement Plans"), for all employees (see separate discussion below).
     Employer contributions to these Retirement Plans are limited by the
     Internal Revenue Code (the "Code") to a total of $30,000 per year. Mesa
     contributed 17% of each employee's total 1993 compensation to the
     Retirement Plans. Second, to the extent that 17% of an employee's total
     compensation exceeded $30,000 (all employees with total compensation in
     excess of $176,470), Mesa, as a matter of policy, paid the excess amount in
     cash to such employee. Third, prior to July 1, 1992, Mesa maintained a key
     employee life insurance program (see separate discussion below) for each
     executive officer and certain other key employees for which Mesa paid the
     majority of the premiums.
 
 (6) Includes the following: a $30,000 Retirement Plans contribution; an $84,750
     payment for a Retirement Plans contribution in excess of the Code
     contribution limitation as described in Note 5 above.
 
 (7) Includes the following: $114,244 of life insurance premiums; a $30,000
     Retirement Plans contribution; a $133,200 payment for a Retirement Plans
     contribution in excess of the Code contribution limitation as described in
     Note 5 above. Also includes cancellation of the previous deferred
     compensation plan for which $3,590,345 had been previously expensed and
     accrued and which was replaced by a split-dollar life insurance program
     that was funded in 1992 at a premium cost of $4,360,608. The net amount
     attributable to 1992 is reflected in the summary compensation table.
 
 (8) Includes the following: a $30,000 Retirement Plans contribution; a $76,253
     payment for a Retirement Plans contribution in excess of the Code
     contribution limitation as described in Note 5 above.
 
 (9) Includes the following: $28,266 of life insurance premiums; a $30,000
     Retirement Plans contribution; a $38,003 payment for a Retirement Plans
     contribution in excess of the Code contribution limitation as described in
     Note 5 above. Also includes cancellation of the previous deferred
     compensation plan for which $323,229 had been previously expensed and
     accrued and which was replaced by a split-dollar life insurance program
     that was funded in 1992 at a premium cost of $500,000. The net amount
     attributable to 1992 is reflected in the summary compensation table.
 
(10) Includes the following: a $30,000 Retirement Plans contribution; a $16,747
     payment for a Retirement Plans contribution in excess of the Code
     contribution limitation as described in Note 5 above.
 
(11) Includes the following: $6,840 of life insurance premiums; a $30,000
     Retirement Plans contribution; a $35,900 payment for a Retirement Plans
     contribution in excess of the Code contribution limitation as described in
     Note 5 above.
 
(12) Includes the following: a $30,000 Retirement Plans contribution; a $4,000
     payment for a Retirement Plans contribution in excess of the Code
     contribution limitation as described in Note 5 above.
 
(13) Includes the following: $3,280 of life insurance premiums; a $30,000
     Retirement Plans contribution; a $25,612 payment for a Retirement Plans
     contribution in excess of the Code contribution limitation as described in
     Note 5 above.
 
(14) Includes the following: a $30,000 Retirement Plans contribution; a $2,467
     payment for a Retirement Plans contribution in excess of the Code
     contribution limitation as described in Note 5 above.
 
(15) Includes the following: $2,187 of life insurance premiums; a $30,000
     Retirement Plans contribution; a $15,396 payment for a Retirement Plans
     contribution in excess of the Code contribution limitation as described in
     Note 5 above.
 
(16) Mr. Littlefair was not an officer of Mesa in 1991.
 
(17) Other compensation amounts are not required to be reported for fiscal years
     ending before December 15, 1992.
 
                                       45
<PAGE>   48
 
BONUS PLAN
 
     The Company has a bonus plan (the "Bonus Plan") under which it may award
bonuses to employees for any calendar year. The amount of the awards to be made
from the Bonus Plan is within the discretion of the Compensation Committee. The
awards are determined by reference to achievement of certain established
objectives by such individuals for the Bonus Plan year, although awards may be
made even if all such objectives are not fully achieved.
 
     Awards to employees other than officers and certain managers generally vest
and are paid in three annual installments. Participants' interests in the awards
vest on December 31 of each year and awards are generally paid near year-end or
in the first quarter of the following year. Deferred bonus awards are deemed
invested in a money market account earning simple interest. In the event of an
offer to acquire all of the business and assets of the Company (or any other
actual change in the control or management of the Company) that is not
previously approved or authorized by the Board of Directors, all unpaid bonus
award installments would be automatically accelerated and paid in full without
regard to the payment schedule provided for in the Bonus Plan.
 
     In prior years, Bonus Plan awards to officers generally vested and were
paid in three installments. However, on July 1, 1992, in conjunction with the
cancellation of the key employee life insurance policies for certain of its
officers and other employees, the Company accelerated the unpaid portion of
bonuses awarded in 1990 and 1991 to such officers and employees (see discussion
under "Key Employee Life Insurance" below). In addition, bonuses for performance
in 1993 were paid to the officers in a lump sum payment in November 1993 as
reflected in the summary compensation table.
 
KEY EMPLOYEE LIFE INSURANCE
 
     The Company has in the past maintained an insurance program for the benefit
of its officers and certain other key employees. The Company paid the major
portion of insurance premiums on policies covering the lives of such persons.
Death benefits were payable to the participant's beneficiaries in the amount
equal to five times the employee's final rate of compensation, and in the case
of Mr. Pickens, five times $1,200,000; the remaining balance would have been
payable to the Company. In the event of retirement or termination for reasons
other than total disability, the participant had the option to continue all or
any portion of the insurance policy at his expense. Any portion not retained by
the participant could be retained by the Company, and the Company would
reimburse the participant for premium payments made that had accrued to the
benefit of the Company.
 
     On July 1, 1992, the Company cancelled the key employee life insurance
policies for certain of its officers, including the officers named in the
summary compensation table, and other employees and collected the aggregate cash
surrender value of $1,210,859. At the same time, the Company accelerated the
deferred portion of bonuses awarded in previous years to such officers and
employees as described in Note 2 to the summary compensation table.
 
DEFERRED COMPENSATION
 
     Prior to June 29, 1992, the Company maintained a deferred compensation
program which provided for payments by the Company to Mr. Pickens and Mr. Cain
(or their surviving beneficiaries) of post-retirement deferred compensation at
the rate of one-half of the participant's final rate of compensation (subject to
minimum amounts specified in the agreements) for a period of 10 years following
the date of retirement, disability or death. As of June 29, 1992, a total of
$3,590,345 had been accrued for Mr. Pickens and $323,229 for Mr. Cain under this
program. To satisfy its accrued and future obligations so that such program
could be discontinued, the Company established the split-dollar life insurance
plan effective June 29, 1992 and executed two separate agreements with Mr.
Pickens and Mr. Cain. The Company purchased insurance policies for Mr. Pickens
and Mr. Cain for a total cost of $4,360,608 and $500,000, respectively. Upon the
purchase of such policies, the Company discontinued the deferred compensation
program without any further obligation to the participants. Both split-dollar
insurance agreements provided that they would terminate during the participant's
lifetime upon the first to occur of (a) either the Company or the participant
giving written notice to the other party that it desired to terminate the
agreement, or (b) the participant attaining age 70.
 
                                       46
<PAGE>   49
 
     The split-dollar life insurance agreements between the Company and Messrs.
Pickens and Cain have been terminated. Mr. Pickens' agreement was terminated
January 5, 1993, and Mr. Cain's agreement was terminated November 12, 1992, and
the cash surrender value of the policies were paid to each individual. The
Company agreed to release the collateral assignment of the policy and release
the participant from any obligation to repay the Company for premium costs and
other amounts specifically set forth in the agreement. Accordingly, the Company
has no further liability under the life insurance policies or under the previous
deferred compensation plan.
 
EMPLOYEES PREMIUM AND PROFIT SHARING PLANS
 
     Mesa maintains the Retirement Plans for the benefit of its employees. Each
year, the Company is required to contribute to the Employees Premium Plan 5% of
the total compensation (as defined in the plan) paid to participants and may
also contribute up to 12% of the total compensation (as defined) to the Profit
Sharing Plan. Participants become 30% vested in their account balances in the
Retirement Plans after three years of service and 40% vested after four years of
service. Participants become vested an additional 20% for each additional year
of service through year seven.
 
     Effective December 31, 1991, all participants were fully vested in their
account balances in the Retirement Plans as a result of certain property
dispositions consummated in 1990 and 1991. Participants shall remain fully
vested in their 1991 balances, but contributions in 1992 and future years under
the Retirement Plans will be subject to the vesting schedule described above.
 
     Prior years of service with the Company's predecessors are counted in the
vesting schedule. Amounts accumulated are distributable under certain
circumstances, including termination of the Retirement Plans.
 
LIMITATION ON CONTRIBUTIONS TO BENEFIT PLANS
 
     Total employer contributions to the Retirement Plans for the account of a
participant in any calendar year are limited as specified by the Code. The Code
provides that annual additions to a participant's account not exceed the lesser
of $30,000 or 25% of the amount of the participant's annual compensation. The
Company, in its discretion, may determine to make cash payment of amounts
attributable to an employee's participation in the Retirement Plans to the
extent they exceed the Code limitations. As a matter of general policy for
employees of the Company, the Company makes annual cash payments directly to
employees to the extent that the annual additions to the account of each such
employee pursuant to the Retirement Plans would exceed the Code limitations.
 
CREDIT SUPPORT OF COMMON UNIT PURCHASES
 
     The Partnership provided credit support by acting as a co-maker on certain
loans made by commercial banks in prior years to Messrs. Cain, Fagerstone,
Hruzek and Littlefair, and certain other employees (not including Mr. Pickens),
the proceeds of which were used to purchase common units of the Partnership in
open market transactions. In conjunction with the Corporate Conversion, the
Company assumed the credit support obligations. The largest aggregate amount
outstanding during 1993 totaled $300,000 to Mr. Cain, $196,244 to Mr.
Fagerstone, $0 to Mr. Hruzek and $0 to Mr. Littlefair. At December 31, 1993, the
unpaid principal balance of such loans totaled $0 to Mr. Cain and $113,731 to
Mr. Fagerstone. Principal on the loan is payable by the employee in quarterly
installments and is due and payable in full on December 1, 1994. The loan bears
interest at a rate of approximately 4.1% per annum. The note is secured by a
certificate of deposit issued to the Company by such commercial bank, bearing
interest at an amount of 2.6% per annum, and in an aggregate amount
approximately equal to the amount owed under the loan. Pursuant to an agreement
between the employee and the Company, the employee will cause the Company to be
relieved of its obligations under such loan upon the termination of employment
for any reason, including death. As between the employee and the Company, the
employee has sole responsibility and liability for repayment of all principal
and interest under his loan and has agreed to indemnify the Company from any
liability or obligation with respect to or arising out of such loan. The purpose
of these arrangements was to encourage and facilitate significant equity
ownership by such key employees.
 
                                       47
<PAGE>   50
 
COMMON STOCK PURCHASE PLAN
 
     The Company has established a common stock purchase program whereby
employees can buy common stock through after-tax payroll deductions. All
full-time employees of the Company and its participating affiliates are eligible
to participate.
 
CERTAIN TRANSACTIONS
 
     The Company permits Mr. Pickens and his affiliates to use Mesa's properties
and assets such as equipment, computers, aircraft and other transportation
equipment for noncompany purposes on terms that are not disadvantageous to Mesa;
however, such terms may be more favorable to Mr. Pickens than those otherwise
available to him. Mr. Pickens and his affiliates were charged a total of $79,002
in 1993, $125,027 in 1992 and $157,500 in 1991 for use of these assets
(principally use of aircraft).
 
     Mesa periodically conducts business meetings and events and hosts customers
and business associates at facilities owned by Mr. Pickens, principally a ranch
and hunting facility. Mesa pays for the use of these facilities at rates
comparable to those charged for similar facilities owned by third parties. In
1993, Mesa paid Mr. Pickens $157,000 in 1993, $149,750 in 1992 and $131,450 in
1991 for the use of the facilities.
 
OPTION PLAN
 
     The Option Plan was approved by stockholders in connection with the
Corporate Conversion in December 1991. The purpose of the Option Plan and the
options issued thereunder is to serve as an incentive to, and to retain, certain
key persons whose training, experience and ability are important to the success
of the Company. Pursuant to the Option Plan, the Option Committee is given the
authority to designate plan participants, to determine the terms and provisions
of options granted thereunder and to supervise the administration of the plan. A
total of 2,000,000 shares of common stock are subject to the plan.
 
     Shares of common stock subject to an option are awarded at an exercise
price that is equivalent to at least 100% of the fair market value of the common
stock on the date the option is granted. The purchase price of the shares as to
which the option is exercised is payable in full at exercise in cash or in
shares of common stock previously held by the optionee for more than six months,
valued at their fair market value on the date of exercise. Subject to Option
Committee approval and to certain legal limitations, an optionee may pay all or
any portion of the purchase price by electing to have the Company withhold a
number of shares of common stock having a fair market value equal to the
purchase price. Options granted under the Option Plan include a limited right of
relinquishment which permits an optionee, in lieu of purchasing the entire
number of shares subject to purchase thereunder and subject to consent of the
Option Committee, to relinquish all or part of the unexercised portion of an
option, to the extent exercisable, for cash and/or shares of common stock in an
amount representing the appreciation in market value of the shares subject to
such options over the exercise price thereof. In its discretion, the Option
Committee may provide for the acceleration of any unvested installments of
outstanding options. The Board of Directors may amend, alter or discontinue the
Option Plan, subject in certain cases to stockholder approval.
 
     The options granted from January 1, 1992 through December 31, 1993 have
exercise prices and vesting schedules as set forth in the following table.
 
<TABLE>
<CAPTION>
            EXERCISE                                           VESTING SCHEDULE
NUMBER OF   PRICE PER   ----------------------------------------------------------------------------------------------
 OPTIONS      SHARE              30%                     55%                     80%                     100%
- ---------   ---------   ----------------------  ----------------------  ----------------------  ----------------------
<S>         <C>         <C>                     <C>                     <C>                     <C>
1,196,000   $ 6.8125    July 10, 1992           January 10, 1993        January 10, 1994        January 10, 1995
  10,000       4.125    November 19, 1992       May 19, 1993            May 19, 1994            May 19, 1995
 156,000     11.6875    April 2, 1993           October 2, 1993         October 2, 1994         October 2, 1995
 120,950      5.8125    November 18, 1993       May 18, 1994            May 18, 1995            May 18, 1996
 485,000       7.375    May 10, 1994            November 10, 1994       November 10, 1995       November 10, 1996
</TABLE>
 
                                       48
<PAGE>   51
 
OPTION/SAR GRANTS IN LAST FISCAL YEAR
 
     Options granted to the Chief Executive Officer and the other four most
highly compensated executive officers of the Company in 1993 are as follows:
 
<TABLE>
<CAPTION>
                                                                                     POTENTIAL REALIZED
                                       PERCENT OF                                     VALUE AT ASSUMED
                        NUMBER OF        TOTAL                                      ANNUAL RATES OF STOCK
                          SHARES      OPTIONS/SARS                                   PRICE APPRECIATION
                        UNDERLYING     GRANTED TO    EXERCISE                          FOR OPTION TERM
                       OPTIONS/SARS   EMPLOYEES IN   OR BASE                        ---------------------
         NAME            GRANTED          1993       PRICE(1)    EXPIRATION DATE      5%($)      10%($)
- ---------------------- ------------   ------------   --------   -----------------   ---------   ---------
<S>                    <C>            <C>            <C>        <C>                 <C>         <C>
Boone Pickens.........    275,000        45.38%       $7.375    November 10, 2003   1,275,477   3,232,309
Paul W. Cain..........    100,000        16.50%        7.375    November 10, 2003     463,810   1,175,385
Dennis E.
  Fagerstone..........     10,000         1.65%        7.375    November 10, 2003      46,381     117,539
S. Leonard Hruzek,
  Jr..................         --           --            --                   --          --          --
Andrew J.
  Littlefair..........     25,000         4.13%        7.375    November 10, 2003     115,952     293,846
</TABLE>
 
- ---------------
 
(1) Of the options listed in the foregoing table, 30% will be vested and
     exercisable beginning May 10, 1994, 55% will be vested and exercisable
     beginning November 10, 1994, 80% will be vested and exercisable beginning
     November 10, 1995 and 100% will be vested and exercisable beginning
     November 10, 1996.
 
AGGREGATED OPTION/SAR EXERCISES IN LAST FISCAL YEAR AND FISCAL YEAR END
OPTION/SAR VALUES
 
     Options exercised in 1993, and the number and value of exercisable and
unexercisable options at December 31, 1993, for the Chief Executive Officer and
the other four most highly compensated executive officers of the Company are as
follows:
 
<TABLE>
<CAPTION>
                                YEAR ENDED                   NUMBER OF SHARES
                             DECEMBER 31, 1993            UNDERLYING UNEXERCISED         VALUE OF UNEXERCISED IN-
                        ---------------------------            OPTIONS/SARS               THE-MONEY OPTIONS/SARS
                           NUMBER OF                       AT DECEMBER 31, 1993            AT DECEMBER 31, 1993
                        SHARES ACQUIRED     VALUE      ----------------------------    ----------------------------
         NAME             ON EXERCISE      REALIZED    EXERCISABLE    UNEXERCISABLE    EXERCISABLE    UNEXERCISABLE
- ----------------------- ---------------    --------    -----------    -------------    -----------    -------------
<S>                     <C>                <C>         <C>            <C>              <C>            <C>
Boone Pickens..........          --        $     --      440,000         635,000           $ 0             $ 0
Paul W. Cain...........          --              --       82,500         167,500             0               0
Dennis E. Fagerstone...          --              --       27,500          32,500             0               0
S. Leonard Hruzek,
  Jr...................          --              --       22,000          18,000             0               0
Andrew J. Littlefair...          --              --       16,500          38,500             0               0
</TABLE>
 
     At December 31, 1993, the Company's common stock per share closed at
$5.625. The exercise price of the granted options reflected in the above table
are $6.8125 and $7.375 per share. Thus, no outstanding options were in-the-money
at such date.
 
COMPENSATION COMMITTEE INTERLOCKS AND INSIDER PARTICIPATION
 
     Mr. Stillwell, a director and member of the Compensation and Option
Committees, is a partner in the law firm of Baker & Botts, L.L.P. The Company
retained Baker & Botts, L.L.P. and incurred legal fees for services of such firm
in 1993. Baker & Botts, L.L.P. has also been retained to provide legal services
in 1994.
 
     Mr. Sarofim, a director and member of the Compensation and Option
Committees, is Chairman of the Board, President and owner of a majority of the
outstanding capital stock of Fayez Sarofim & Co., which acts as an investment
advisor to certain employee benefit plans of the Company. During the year ended
December 31, 1993, Fayez Sarofim & Co. earned $139,687 for such services.
 
                                       49
<PAGE>   52
 
             SECURITY OWNERSHIP OF PRINCIPAL OWNERS AND MANAGEMENT
 
SECURITY OWNERSHIP OF MANAGEMENT
 
     The following table presents certain information as to the beneficial
ownership of the Company's Common Stock as of January 10, 1994 by the directors
and officers of the Company, individually and as a group.
 
<TABLE>
<CAPTION>
                                                                                   PERCENTAGE
                                                          NUMBER OF SHARES OF          OF
                                                            COMMON STOCK(1)       COMMON STOCK
                                                          -------------------     ------------
    <S>                                                        <C>                  <C>
    Board of Directors:
      Paul W. Cain......................................         130,139             *
      John S. Herrington................................          10,000             *
      Wales H. Madden, Jr...............................           5,000             *
      Boone Pickens(2)..................................       3,040,126            6.28%
      Fayez S. Sarofim..................................         400,000             *
      Robert L. Stillwell...............................          26,500             *
      J.R. Walsh, Jr.(3)................................          25,520             *
    Officers:
      Dennis E. Fagerstone..............................          49,084             *
      S. Leonard Hruzek, Jr.............................          36,815             *
      Andrew J. Littlefair..............................          33,613             *
      Charles L. Carpenter..............................           5,500             *
      William D. Ballew.................................          26,103             *
    Directors and Officers as a group (12 persons)......       3,788,400            7.53%
</TABLE>
 
- ---------------
  * Less than 0.1%
 
(1)  Includes shares issuable upon the exercise of options that are exercisable
     within sixty days of January 10, 1994, as follows: 640,000 shares for Mr.
     Pickens, 120,000 for Mr. Cain, 40,000 for Mr. Fagerstone, 32,000 for Mr.
     Hruzek, 24,000 for Mr. Littlefair, 5,500 for Mr. Carpenter, 24,000 for Mr.
     Ballew and 885,500 for all directors and officers as a group.
 
(2)  The above amounts include 7,545 shares of Common Stock owned by several
     trusts for Mr. Pickens' children, of which he is a trustee and over which
     he has sole voting and investment power over such shares, although he has
     no economic interest therein. The above amounts exclude 2,798 shares of
     Common Stock owned by Mrs. Pickens as her separate property, as to which
     Mr. Pickens disclaims beneficial ownership and with respect to which he
     does not have or share voting or investment power.
 
(3)  Excludes 1,027 shares of Common Stock owned by Mrs. Walsh as her separate
     property, as to which Mr. Walsh disclaims beneficial ownership and with
     respect to which he does not have or share voting or investment power.
 
                                       50
<PAGE>   53
 
CERTAIN BENEFICIAL OWNERS
 
     The table below sets forth certain information as of January 10, 1994
regarding each person or "group" (as that term is used in Section 13(d)(3) of
the Securities Exchange Act of 1934) known by the Company to own beneficially
more than 5% of the Common Stock. Information is based on the most recent
Schedule 13D or 13G filed by such holder with the Commission or other
information provided by the holder to the Company.
 
<TABLE>
<CAPTION>
                                                               AMOUNT AND NATURE OF BENEFICIAL
                                                                          OWNERSHIP
                                                            --------------------------------------
                                                                                       PERCENTAGE
                                                            NUMBER OF SHARES OF            OF
           NAME AND ADDRESS OF BENEFICIAL OWNER                COMMON STOCK           COMMON STOCK
- ----------------------------------------------------------  -------------------       ------------
<S>                                                         <C>                       <C>
Boone Pickens.............................................       3,040,026(1)             6.28%
2600 Trammell Crow Center
2001 Ross Avenue
Dallas, Texas 75201
FMR Corp. ................................................       4,816,959(2)            11.95%
82 Devonshire Street
Boston, Massachusetts 02109
</TABLE>
 
- ---------------
 
(1) See notes (1) and (2) to the table under "Security Ownership of Management"
     above.
 
(2) The Schedule 13G filed by FMR Corp. states that such firm has the sole power
     to vote or to direct the vote of 157,855 shares, and the sole power to
     dispose or to direct the disposition of 4,816,959 shares. Furthermore,
     various persons have the right to receive or the power to direct the
     receipt of dividends from, or the proceeds from the sale of, the Common
     Stock. The interest of one person, Fidelity Magellan Fund, an investment
     company, amounts to 2,047,641 shares, or 5.08% of the total outstanding
     shares of Common Stock at November 30, 1993.
 
                                       51
<PAGE>   54
 
                        DESCRIPTION OF THE SECURED NOTES
 
     The Secured Notes offered hereby will be issued under the Indenture dated
as of May 1, 1993, between the Obligors and Harris Trust and Savings Bank, as
trustee (the "Secured Trustee"), as amended by the First Supplemental Indenture
dated as of January 5, 1994, between the Obligors and the Trustee (as so amended
and supplemented, the "Secured Indenture"). The following summaries of certain
provisions of each of the Secured Notes, the Secured Indenture, the related
Security Instruments and the Intercreditor Agreement do not purport to be
complete and are subject to, and qualified in their entirety by reference to,
all of the provisions of such documents, including those terms made part of the
Secured Indenture by reference to the Trust Indenture Act of 1939 as in effect
on the date of the Secured Indenture. Copies of the Secured Indenture, the
related Security Instruments and the Intercreditor Agreement have been filed as
exhibits to the Registration Statement of which this Prospectus is a part.
 
     See "-- Certain Definitions Used in the Secured Indenture" below for the
meanings assigned to certain capitalized terms in this section.
 
GENERAL
 
     The Secured Notes will be issued only in registered form, without coupons,
in denominations of $1,000 face amount (at maturity) and integral multiples of
$1,000. The Secured Notes will be limited to an aggregate face amount (at
maturity) equal to the sum of (i) $569,277,000, which was the aggregate face
amount (at maturity) of Secured Notes issued pursuant to the Exchange Offer plus
(ii) the maximum aggregate face amount (at maturity) of Secured Notes being
offered hereby, which additional Secured Notes will be issued pursuant to the
provisions of the Secured Indenture described below under the caption
"Additional Secured Notes." The Secured Notes offered hereby will be fungible
with the currently outstanding Secured Notes. The Secured Notes are the joint
and several obligations of the Company, MOC and Capital.
 
MATURITY DATE
 
     The Secured Notes will mature on June 30, 1998.
 
YIELD AND INTEREST
 
     The yield to maturity of a Secured Note is 12 3/4%. This yield to maturity
is based on the following terms of the Secured Notes (expressed per $1,000 face
amount): (i) the Accreted Value of a Secured Note of approximately $830.77 at
December 31, 1993, (ii) the increase in Accreted Value of a Secured Note to
$1,000 from December 31, 1993 through and including June 30, 1995, (iii) cash
interest payments at 12 3/4% per annum paid semiannually in arrears thereafter,
and (iv) the payment of $1,000 (representing the Accreted Value as of December
31, 1993 of approximately $830.77 plus the cumulative increase in Accreted Value
from December 31, 1993 through and including June 30, 1995, totalling
approximately $169.23) at maturity.
 
     The Secured Notes do not bear any cash interest through and including June
30, 1995. However, the Accreted Value of the Secured Notes will increase from
December 31, 1993 through and including June 30, 1995, at a rate of 12 3/4% per
annum, compounded semiannually and each June 30 and December 31. On July 1,
1995, the Secured Notes will have a final Accreted Value of an integral multiple
of $1,000. From and after July 1, 1995, the Secured Notes will accrue interest
at a rate of 12 3/4% per annum, payable semiannually in arrears on each June 30
and December 31, commencing December 31, 1995, to holders of record at the close
of business on the June 15 or December 16 next preceding such June 30 or
December 31. Interest shall be payable in cash only.
 
     Accreted Value and interest is payable, and the Secured Notes are
transferable, at the offices or agencies of the Secured Trustee in New York, New
York and Chicago, Illinois, provided that payment of interest may be made at the
Obligors' option by check mailed to the registered holders of the Secured Notes
at their addresses appearing in the Secured Note registers. No service charge
shall be made for any registration of transfer or exchange of the Secured Notes,
but the Obligors or the Secured Trustee may require payment of a sum sufficient
to cover any transfer tax or any similar governmental charge payable in
connection therewith.
 
                                       52
<PAGE>   55
 
     The Obligors shall pay interest on overdue amounts, to the extent permitted
by law, at the rate of 12 3/4% per annum, compounded semiannually.
 
PROVISIONS RELATING TO THE ISSUANCE OF THE ADDITIONAL SECURED NOTES OFFERED
HEREBY
 
     The Secured Indenture provides that
 
          (a) The Obligors may issue additional Secured Notes (i.e., in addition
     to the $569,277,000 face amount (at maturity) currently outstanding) in an
     aggregate face amount (at maturity) not to exceed the amount contemplated
     by clause (c) below for the purpose of settling or compromising in its
     entirety, or satisfying or compromising in its entirety any judgment
     entered in, the Unocal lawsuit. See "Business -- Legal Proceedings."
 
          (b) Effective upon the authentication and issuance of any additional
     Secured Notes, the Company and/or MOC shall grant to the Secured Trustee
     for the pro rata benefit of the holders of Secured Notes (including those
     persons in whose name the additional Secured Notes being offered in the
     Offering will be registered) a lien upon and security interest in a limited
     partnership interest in HCLP, as further provided in clause (c) below. Such
     security interest shall be subordinate, junior and inferior to the lien and
     security interest granted upon and in such partnership interest in favor of
     the holders of any First Lien Debt (including, without limitation, the
     lending banks under the Credit Agreement) and shall be granted pursuant to
     either (i) an amendment or supplement to the Pledge Agreement or (ii) an
     additional pledge agreement substantially in the form of the Pledge
     Agreement and granting to the Secured Trustee for the benefit of the
     holders of Secured Notes a lien and security interest in such limited
     partnership interest of like tenor and effect as that granted pursuant to
     the Pledge Agreement. Upon the execution and delivery thereof, the limited
     partnership interest pledged shall constitute "HCLP Collateral" for all
     purposes under the Secured Indenture.
 
          (c) In respect of each 1% limited partnership interest in HCLP (out of
     100% of all partnership interests in HCLP) with respect to which the
     Company and/or MOC grants a security interest to the Secured Trustee, the
     Obligors may issue up to $4,248,036 aggregate face amount (at maturity)
     ($3,250,000 Accreted Value at May 1, 1993) of additional Secured Notes.
 
RANKING OF SECURED NOTES
 
     The indebtedness evidenced by the Secured Notes is subordinate in right of
payment to the extent set forth in the Secured Indenture to all existing and
future First Lien Debt of any of the Obligors. The indebtedness evidenced by the
Secured Notes ranks senior in right of payment to the Obligors' 12% Subordinated
Notes and 13 1/2% Subordinated Notes. The Secured Notes rank pari passu with the
Unsecured Notes.
 
     In the event and during the continuation of any Senior Debt Default (as
defined below) in respect of the First Lien Debt of any Obligor, no payment
shall be made by such Obligor on the Secured Notes (including any deposit
pursuant to the Secured Notes and any payment in respect of any repurchase,
redemption or other retirement of any Secured Notes) unless and until such
Senior Debt Default shall have been remedied, nor shall any such payment
(including any deposit pursuant to the Secured Notes and any payment in respect
of any repurchase, redemption or other retirement of any Secured Notes) be made
if after giving effect, as if paid, to such payment, any Senior Debt Default of
any Obligor would exist; provided that, with respect to a Senior Debt Default of
any Obligor, other than a default in any principal (including mandatory
prepayments) or interest payment with respect to First Lien Debt of such
Obligor, such Obligor will not be prevented from making any regularly scheduled
payment of principal or interest on the Secured Notes as and when the same shall
become payable in accordance with their terms by such Obligor for a period
exceeding the greater of (i) 120 days after the receipt by holders of such First
Lien Debt of notice from such Obligor of such Senior Debt Default and (ii) any
period during which the First Lien Debt in respect of which a Senior Debt
Default so exists has been declared due and payable in its entirety and (x) such
acceleration has not been rescinded or annulled or (y) such First Lien Debt has
not been paid in full. Upon any distribution of assets of any Obligor in
connection with any winding up or liquidation of such Obligor or any
reorganization, bankruptcy or other similar proceeding with respect to any
Obligor, the holders of all First Lien Debt of such Obligor will first be
entitled to receive payment in full of all such First Lien Debt before the
holders of the Secured Notes will be
 
                                       53
<PAGE>   56
 
entitled to receive any payment on such Secured Notes from such Obligor. No part
of the Secured Notes shall have any claim to the assets of any Obligor on a
parity with or prior to the claim of the holders of such First Lien Debt of such
Obligor.
 
     At December 31, 1993, $69.5 million of First Lien Debt was outstanding,
consisting of $59.1 million of borrowings and $10.4 million in letter of credit
obligations under the Credit Agreement. In addition, HCLP had outstanding $541.6
million principal amount of HCLP Secured Notes at December 31, 1993. Because the
Obligors' interest in HCLP is an equity interest as partner, holders of
indebtedness of HCLP would have a priority with respect to the assets of HCLP
over the Obligors' interest in the event of a liquidation or bankruptcy of HCLP.
The Secured Indenture restricts the incurrence of additional First Lien Debt (as
defined) and other Debt by the Obligors and their Qualified Subsidiaries (as
defined). HCLP is not a Qualified Subsidiary. See "-- Limitation on Incurrence
of First Lien Debt" and "-- Limitation on Incurrence of Other Debt" below.
 
     As a result of the above-described provisions, in the event of the
insolvency of an Obligor or any subsidiary, holders of the Secured Notes may
recover ratably less than general creditors of such Obligor or subsidiary.
 
SECURITY
 
     The Obligors' obligation to pay the Secured Notes is secured by a Deed of
Trust, Assignment of Production, Security Agreement and Financing Statement (the
"Mortgage") and a Security Agreement, Pledge and Financing Statement (the
"Pledge Agreement" and, together with the Mortgage, the "Security Instruments").
The Security Instruments grant a second lien on and security interest in all
right, title and interest of MOC in (i) the "B" Contract and the leases
described or referred to therein, all hydrocarbons, helium and other minerals
in, under, upon, produced or to be produced or which may be produced therefrom,
all contractual rights related thereto, the operating equipment used thereon and
the revenues and proceeds thereof or related thereto (the "West Panhandle
Collateral"), and (ii) a 65% limited partnership interest in HCLP (which will be
increased to approximately 77% upon issuance of the Secured Notes offered
hereby), being part of the limited partnership interest in HCLP owned by MOC
(the "HCLP Collateral" and, together with the West Panhandle Collateral, the
"Collateral"), to the Secured Trustee, as trustee, as security for the Obligors'
obligations under the Secured Indenture and the Secured Notes. The lien of the
Security Instruments with respect to the Collateral is subordinated to the lien
with respect to such Collateral securing the Credit Agreement and any other
First Lien Debt created or incurred hereafter as provided herein. The Secured
Trustee's interest in the Collateral equally and ratably secures the Secured
Notes, including both the currently outstanding Secured Notes and the Secured
Notes offered hereby. Currently, the HCLP Collateral consists of only a 65%
limited partnership interest in HCLP. The additional approximately 12% HCLP
limited partnership interests are being pledged by MOC in connection with the
Offering and as contemplated by the provisions of the Secured Indenture
described above under the caption "Additional Secured Notes." The Security
Instruments provide that, in the event no First Lien Debt is outstanding, upon a
foreclosure on the Collateral, pursuant to the Security Instruments, and a
disposition of such Collateral, the proceeds from such disposition will be
applied to pay all amounts owing with respect to outstanding Secured Notes.
 
     Intercreditor Agreement. The rights of the Secured Trustee under the
Security Instruments are, during any period in which any First Lien Debt is
outstanding, subject to the terms of an Intercreditor Agreement dated as of
August 26, 1993 among Societe Generale, Southwest Agency, as agent for the Banks
under the Credit Agreement (the "Agent Bank"), the Secured Trustee and the
trustee for the Unsecured Notes (the "Intercreditor Agreement"). In the
Intercreditor Agreement, the Secured Trustee and the Agent Bank agreed that the
lien of the Agent Bank in the Collateral is senior, superior and prior to the
lien of the Secured Trustee in the Collateral and that the lien of the Secured
Trustee in the Collateral is subordinate, junior and inferior to that of the
Agent Bank. In addition, the Secured Trustee and the trustee for the Unsecured
Notes acknowledged and agreed that the Discount Notes are subordinate, junior
and inferior to the obligations of the Company and MOC under the Credit
Agreement.
 
     Among other things, the Intercreditor Agreement provides that (i) upon the
occurrence of an event of default under the Credit Agreement, the Agent Bank may
exercise any of its rights under the Credit Agreement and the related security
instruments with respect to the Collateral, (ii) except as specifically
 
                                       54
<PAGE>   57
 
provided in the Intercreditor Agreement, the Secured Trustee may not, without
the prior written consent of the Agent Bank, exercise any of its rights with
respect to the Collateral, including seeking to foreclose upon its lien against
the Collateral or any part thereof and (iii) the Intercreditor Agreement shall
not limit the ability of the Secured Trustee and the trustee for the Unsecured
Notes or the holders of Secured Notes or Unsecured Notes to accelerate the
maturity of such Secured Notes or Unsecured Notes or to file claims in respect
thereof in any bankruptcy or insolvency proceeding involving an Obligor. The
Intercreditor Agreement also provides that if, after the occurrence of an event
of default under the Credit Agreement, the Agent Bank proposes to release its
lien on any Collateral in connection with the sale thereof (i) pursuant to the
Credit Agreement and the related security instruments or (ii) by any Obligor,
then the Secured Trustee shall execute and deliver to the Agent Bank such
releases, termination statements and other release documents as the Agent Bank
may request to release the Secured Trustee's lien on such Collateral. The
Intercreditor Agreement also provides that if, prior to the occurrence of an
event of default under the Credit Agreement, the Agent Bank consents to a sale,
exchange, release or other disposition of Collateral, the Secured Trustee and
the trustee for the Unsecured Notes shall be deemed to have consented thereto
provided that any such transaction complies with the applicable provisions of
the Secured Indenture described below under the captions "Disposition of
Collateral and Other Assets" and "Release of Collateral."
 
     The Intercreditor Agreement provides that the proceeds of any sale or other
disposition of any Collateral and the proceeds from any casualty insurance
insuring any Collateral shall be distributed in the following order of priority:
(i) first to the Agent Bank for its reasonable costs and expenses in connection
with matters relating to the Collateral, (ii) second, to the Agent Bank in an
amount equal to the unpaid obligations under the Credit Agreement (including
cash collateral for any outstanding letters of credit), (iii) third, to the
Secured Trustee for application in accordance with the Secured Indenture and
(iv) fourth, any surplus then remaining from such proceeds shall be distributed
to the Obligors, or to whomever may be lawfully entitled to receive the same, or
as a court of competent jurisdiction may direct.
 
DISPOSITION OF COLLATERAL AND OTHER ASSETS
 
     The Secured Indenture provides that MOC may not effect a Collateral Sale
unless the provisions of either clause (a) or clause (b) below are satisfied.
 
          (a) If the Cash Proceeds from such Collateral Sale equal or exceed the
     Release Price applicable to such Collateral, an amount of Cash Proceeds
     equal to (x) the Release Price applicable to such Collateral less (y) an
     amount equal to the aggregate amount of any payments that the Obligors are
     required (pursuant to or as contemplated by the agreements governing any
     First Lien Debt then outstanding) to make from such Cash Proceeds in
     respect of such First Lien Debt, shall immediately become Collateral upon
     receipt thereof by MOC and shall be deposited into the Collateral Account.
 
          (b) If the Cash Proceeds from such Collateral Sale are less than the
     Release Price applicable to such Collateral, an amount of Cash Proceeds
     equal to (x) all of the Cash Proceeds received as a result of such
     Collateral Sale(s) less (y) an amount equal to the aggregate amount of any
     payments that the Obligors are required (pursuant to or as contemplated by
     the agreements governing any First Lien Debt then outstanding) to make from
     such Cash Proceeds in respect of such First Lien Debt, shall immediately
     become Collateral upon receipt thereof by MOC and shall be deposited into
     the Collateral Account. In such an event, the Cash Proceeds to be paid to
     MOC pursuant to such Collateral Sale shall not be less than the fair market
     value of the Collateral sold pursuant to such sale. For any Collateral Sale
     or series of related Collateral Sales subject to this clause (b) in which
     the aggregate purchase price exceeds $10,000,000, MOC shall deliver to the
     Trustee an opinion of an Independent Financial Advisor to the effect that
     the aggregate consideration received is not less than the fair market value
     of the Collateral sold.
 
          (c) The amount of Cash Proceeds required to be deposited into the
     Collateral Account with respect to a Collateral Sale pursuant to clause (a)
     or (b) above is referred to herein as the "Release Amount" with respect to
     such Collateral.
 
     The Secured Indenture also provides that (a) no Obligor may sell, assign,
lease, transfer, convey or otherwise dispose of any asset that does not
constitute Collateral, including its equity interest in any subsidiary,
 
                                       55
<PAGE>   58
 
unless the consideration paid to such Obligor is not less than the fair market
value of such asset and (b) MOC shall not consent, in its capacity as a limited
partner of HCLP, to the sale or other disposition by HCLP, of any property
pursuant to Section 6.10 of the HCLP partnership agreement for less than fair
market value thereof.
 
RELEASE OF COLLATERAL
 
     The Secured Indenture provides that upon receipt of a release request from
the Obligors, and subject to certain conditions, the Secured Trustee shall
release all or a part of the Collateral from the Security Interests. Any such
release request shall certify that one of the conditions set forth below
(together with certain other conditions), have been, or simultaneously with or
immediately following the release will be, fulfilled: (i) the Collateral will be
released in compliance with certain provisions of the Secured Indenture
regarding, among other things, disposition or replacement of machinery or
equipment and disposition of inventory or accounts receivable in the ordinary
course of business; or (ii) there is a substitution of Substitute Collateral (as
defined); or (iii) there is a deposit of Cash Collateral; or (iv) the Collateral
to be released is insurance proceeds and such Collateral is used to commence,
continue or complete the repair, restoration, replacement or rebuilding of
Property that was damaged, destroyed or injured and for which such insurance
proceeds were paid, substantially to the condition and character of such
Property immediately prior to such damage, destruction or injury; or (v) the
Obligors represent in the release request that Collateral held in the Collateral
Account that is to be released will be used, and within 60 days is used, either
to make payments of the Stated Price (without any premium) of the Secured Notes
in connection with optional redemptions of Secured Notes pursuant to the Secured
Indenture or to otherwise purchase Secured Notes; or (vi) the Obligors represent
in the release request that the Collateral is to be released in connection with
a Collateral Sale made in compliance with the covenant described under the
caption "Disposition of Collateral and Other Assets" above and that the Release
Amount with respect to such Collateral Sale will be deposited into the
Collateral Account; or (vii) all of the conditions precedent to the termination
of the Security Instrument under which the lien in the Collateral to be released
was created, or to the release of such Collateral from the lien created by such
Security Instrument, as set forth in such Security Instrument, have been
satisfied; or (viii) a Requisite Majority have consented in writing to such
release of Collateral from the Security Interests.
 
IMPAIRMENT OF SECURITY INTEREST
 
     The Secured Indenture provides that the Obligors may not, and may not
permit any subsidiary to, take any action that would have the result of
impairing the Security Interests unless such action is (i) permitted by the
Security Instruments, or (ii) in the case of Collateral Sales, taken in
compliance with the requirements of the covenant described under the caption
"Disposition of Collateral and Other Assets" above.
 
AMENDMENTS TO B CONTRACT
 
     The Secured Indenture provides that, after the date Secured Notes were
first issued (i.e., August 26, 1993), the Obligors may not amend, modify or
supplement the terms of the B Contract (as defined in the Mortgage) if such
amendment, modification or supplement (taken as a whole together with all other
amendments, modifications and supplements being concurrently effected) would
have a material adverse effect on the Secured Notes, the holders thereof or the
Collateral.
 
MANDATORY RETIREMENT
 
     The Secured Indenture provides that on or before each Mandatory Retirement
Notice Date (as defined below) on which the amount of Mandatory Retirement Funds
(as defined below) exceeds zero, the Obligors shall either (a) in accordance
with the redemption provisions of the Secured Indenture, mail a notice of
redemption stating that the Applicable Amount of Secured Notes (as defined
below) issued thereunder will be redeemed on the related Mandatory Retirement
Date (as defined below) or (b) make an offer to purchase (a "Retirement Offer")
the Applicable Amount of Secured Notes issued thereunder, such purchase to be
effected on the related Mandatory Retirement Date. The purchase or redemption
price for any mandatory retirement of Secured Notes shall be equal to the Stated
Price of the Secured Notes as of such Mandatory Retirement Date.
 
                                       56
<PAGE>   59
 
     The indenture for the Unsecured Notes has a covenant substantially similar
to the foregoing covenant. The Obligors shall be required to redeem or purchase
(pursuant to a Retirement Offer or otherwise) all of the outstanding Unsecured
Notes before any Secured Notes can be redeemed or purchased in respect of
Mandatory Retirement Funds. In connection with any such offer to purchase
Secured Notes, the Obligors would comply with all applicable tender offer rules,
including, without limitation, Section 14(e) of the Exchange Act and the rules
promulgated thereunder and any other then applicable regulatory requirements.
 
     The Credit Agreement prohibits the Obligors from redeeming, purchasing or
otherwise acquiring any of the Secured Notes or other subordinated debt,
provided, however, that, notwithstanding the foregoing, if no default under the
Credit Agreement has occurred and is continuing immediately prior to and after
giving effect to such a redemption, purchase or other acquisition, Mesa may
redeem, or otherwise acquire, Secured Notes and subordinated debt (i) through
the application of the net proceeds from the issuance or sale of certain
refinancing debt or of equity securities of Mesa or (ii) in an amount not to
exceed $75,000,000 (in addition to amounts permitted by clause (i) above) after
the aggregate commitment of the banks is equal to or less than $50 million and
either Mesa has prevailed at trial in the Unocal lawsuit (as described herein)
or such lawsuit has otherwise been resolved, settled or terminated. See
"Business -- Legal Proceedings." Any future credit agreements or other
agreements relating to First Lien Debt to which the Company or MOC becomes a
party may contain similar restrictions and provisions. In the event the Secured
Indentures require the Obligors to apply Mandatory Retirement Funds to redeem or
purchase Secured Notes at a time when the Obligors are prohibited from doing so,
the Obligors could seek the consent of their lenders to redeem or purchase
Secured Notes or could attempt to refinance the borrowings that contain such
prohibition. If the Obligors did not obtain such a consent or repay such
borrowings, the Obligors would remain prohibited from redeeming or purchasing
the Secured Notes. In such case, the Obligors' failure to redeem or purchase
tendered Secured Notes would constitute an Event of Default under the Secured
Indenture. In such circumstances, the subordination provisions in the Secured
Indenture would likely restrict payments to the holders of the Secured Notes.
 
OPTIONAL REDEMPTION
 
     The Secured Notes may be redeemed at the option of the Obligors, in whole
at any time or in part from time to time, upon at least 30 days' but not more
than 60 days' notice, by payment of the following redemption prices (expressed
as percentages of the Accreted Value thereof as of the redemption date) if
redeemed during the six month period beginning January 1 or July 1, as the case
may be, of the years indicated below:
 
<TABLE>
<CAPTION>
        YEAR                                                    JANUARY 1     JULY 1
        ----                                                    ---------    ---------
        <S>                                                     <C>          <C>
        1994..................................................   110.250%     107.494%
        1995..................................................   105.032%     102.867%
        1996..................................................   100.956%     100.000%
</TABLE>
 
and thereafter at 100% of the Accreted Value of the Secured Notes as of the
redemption date, plus, if the redemption date is after June 30, 1995, accrued
but unpaid interest on the Secured Notes to the redemption date.
 
     If less than all of the Secured Notes are to be redeemed, the Secured Notes
shall, as nearly as is practicable without requiring the issuance of any
fractional Secured Notes and consistent with the provisions of such Secured
Indenture, be redeemed pro rata from the holders thereof. The Secured Trustee
shall select, in a manner consistent with the preceding sentence, the Secured
Notes to be redeemed; provided that if pro rata redemption is not then permitted
by any applicable law, rule or regulation, the Secured Trustee shall select
Secured Notes to be redeemed by lot or by such other method that complies with
the requirements of any exchange on which such Secured Notes may then be listed
or that such Secured Trustee otherwise considers appropriate. If any Secured
Note is to be redeemed in part only, the notice of redemption relating to such
Secured Note shall state the portion of the face amount (at maturity) (in
integral multiples of $1,000) to be redeemed and that a new certificate or
certificates representing the Secured Notes in face amount (at maturity) equal
to the unredeemed portion thereof will be issued in the name of the holder
thereof upon surrender of the original Secured Note.
 
                                       57
<PAGE>   60
 
LIMITATION ON RESTRICTED PAYMENTS
 
     The Secured Indenture provides that the Obligors may not, and may not
permit any of their subsidiaries to, directly or indirectly make any loans,
advances or capital contributions to HCLP in an amount greater than the amount
permitted by clause (iii)(1) of the covenant described under the caption
"Restrictions on Investments, Loans and Advances" below or make any loans,
advances or capital contributions to Non-Qualified Subsidiaries other than HCLP
in an aggregate amount exceeding $4,000,000 per fiscal year or declare or pay
any dividend or distribution (other than a dividend or distribution of Equity
Securities of the Company) in respect of any Equity Securities of the Company or
purchase, redeem or otherwise acquire or retire for value any Equity Securities
of the Company or purchase, redeem or otherwise acquire or retire for value
(other than at maturity or pursuant to mandatory sinking fund or redemption
provisions) any Subordinated Debt (all such loans, advances or capital
contributions (in an amount exceeding the amount permitted by clause (iii)(1) of
the covenant described under the caption "Restrictions on Investments, Loans and
Advances" below) to HCLP and all such loans, advances or capital contributions
(in an amount exceeding $4,000,000 per fiscal year) to Non-Qualified
Subsidiaries other than HCLP, and all such dividends, distributions, purchases,
redemptions or other acquisitions or retirements being collectively referred to
as "Restricted Payments"), unless (i) no Default or Event of Default shall have
occurred and be continuing at the time of such Restricted Payment and no Event
of Default shall occur as a consequence thereof, and (ii) after giving effect to
such Restricted Payment, all Restricted Payments made subsequent to June 30,
1993 (other than acquisitions and retirements of Equity Securities and
Subordinated Debt described in clause (x) or (y) below) do not exceed the sum
of: (1) 40% of Consolidated Net Income if positive, or 100% of Consolidated Net
Income if negative, in each case as earned subsequent to June 30, 1993 and (2)
the net proceeds of the issuance or sale after June 30, 1993 of (a) Equity
Securities of the Company and (b) Debt (except for the Convertible Notes) issued
after consummation of the Exchange Offer that has been converted into Equity
Securities of the Company; provided, however, that the foregoing provisions
shall not prevent (w) the payment of any dividend or distribution within 60 days
after the date of declaration thereof, if at said date of declaration the
conditions in clauses (i) and (ii) above were satisfied or (x) the acquisition
or retirement of any Equity Securities by exchange for, or out of the proceeds
of a substantially concurrent issuance or sale of, other Equity Securities or
(y) the acquisition or retirement of any Subordinated Debt by exchange for, or
out of the proceeds of a substantially concurrent issuance or sale, of Equity
Securities of the Company or Refinancing Debt permitted by the Secured Indenture
or (z) the payment of any dividend on any class or series of preferred stock
that has been issued in exchange for, or the net proceeds from the issuance or
sale of which have been used to purchase, redeem or otherwise acquire or retire
Secured Notes, Unsecured Notes or any Refinancing Debt issued in respect of
Secured Notes or Unsecured Notes, provided that the annual dividend rate on such
preferred stock does not exceed the annual interest rate on such Debt (or, if
such Debt provided for periodic accretion of principal in lieu of interest, the
annual accretion on such Debt) and that no mandatory redemption or sinking fund
payments are required on such preferred stock prior to July 1, 1998.
Notwithstanding the foregoing, the Obligors may not make any Restricted Payment
before December 31, 1995, except for any Restricted Payment described in clause
(y) or above.
 
LIMITATION ON INCURRENCE OF FIRST LIEN DEBT
 
     The Secured Indenture provides that the Obligors may not, and may not
permit any subsidiaries of the Company to, create, incur, issue, assume or
otherwise become liable with respect to any First Lien Debt unless immediately
thereafter the aggregate principal amount (including reimbursement obligations
under letters of credit) of First Lien Debt then outstanding shall not exceed
the greater of (i) such amount of First Lien Debt outstanding immediately prior
thereto or (ii) $82,500,000 multiplied by the difference between 1 minus the
quotient of (x) the aggregate amount of net proceeds of all Collateral Sales
occurring after the date hereof and prior to the time of determination that are
used to repay First Lien Debt divided by (y) the sum of the Secured Debt Amount
immediately prior to such time plus the sum of the respective Stated Prices of
all Secured Notes retired, redeemed, repurchased or otherwise acquired by any of
the Obligors prior to such time (such Stated Prices being determined as of the
respective date of such retirement, redemption, repurchase or acquisition).
 
                                       58
<PAGE>   61
 
LIMITATION ON INCURRENCE OF OTHER DEBT
 
     The Secured Indenture provides that, except for permitted First Lien Debt,
the Obligors may not, and may not permit any of their Qualified Subsidiaries to,
create, incur, issue, assume, guaranty or otherwise become liable (including,
without limitation, by merger, amalgamation or consolidation with or acquisition
of any person) with respect to (i) any Debt, other than the Secured Notes and
the Unsecured Notes, that is pari passu with the Secured Notes, or any
Subordinated Debt that has either a sinking fund obligation or principal payment
requirement on or prior to June 30, 1998, unless, immediately after giving
effect to the incurrence of such Debt and the application of the proceeds
therefrom, the Cash Flow Coverage Ratio shall be greater than or equal to 2.25
to 1.0, or (ii) any other Subordinated Debt unless, immediately after giving
effect to the incurrence of such Debt and the application of the proceeds
therefrom, the Cash Flow Coverage Ratio shall be greater than or equal to 2.0 to
1.0.
 
     Notwithstanding the limitations imposed by the foregoing paragraph, any of
the Obligors and any of their Qualified Subsidiaries may, directly or
indirectly, create, incur, issue, assume, guaranty or otherwise become liable
with respect to any or all of the following:
 
          (i) Debt set forth on Schedule 1 to the Secured Indenture (the
     "Existing Debt"), subject to any increase thereon permitted by clause
     (viii) of the covenant described under the caption "Restrictions on
     Investments, Loans and Advances" below and subject to any reduction thereof
     required by the covenant described under the caption "Repayment of
     Intercompany Debt" below;
 
          (ii) the Secured Notes and the Unsecured Notes, together with any
     other obligations under the Indenture therefor;
 
          (iii) obligations in respect of the Subordinated Notes and the
     Indenture therefor;
 
          (iv) additional Secured Notes, if any, issued in accordance with the
     Secured Indenture as described under the caption "Additional Secured Notes"
     above (i.e., the Secured Notes being offered in the Offering);
 
          (v) Debt issued in exchange for, or to refund or refinance, all or any
     portion of any Debt permitted under clauses (i) through and including this
     clause (v) of this covenant (any such Debt issued in exchange or to refund
     or refinance being referred to herein as "Refinancing Debt"); provided,
     however, that such Refinancing Debt (a) shall be issued by no person in
     addition to the issuer or issuers of the Debt being refinanced; (b) shall
     not have increased the amount of Consolidated Debt (net of any cash
     reserves required to be maintained for the benefit of the holders of the
     Refinancing Debt and funded with proceeds of such Refinancing Debt) other
     than in an amount no greater than the reasonable out-of-pocket costs and
     expenses incurred by the issuer of such Refinancing Debt in connection with
     the negotiation, documentation, sale and closing of the applicable
     refunding or refinancing, as the case may be; (c) shall have an average
     life to maturity equal to or longer than that of the Debt being refinanced
     (determined as of the date of the proposed refinancing); (d) shall be at
     least as junior or no more senior in right of payment to the Secured Notes,
     as the case may be, as the Debt being refinanced and (e) shall have been
     approved by the board of directors of the Company, taking into account the
     obligations of the Obligors under the Secured Indenture and the Secured
     Notes; provided, however, that such approval shall be required only if such
     Refinancing Debt has an aggregate principal amount or accreted value at the
     time of issuance (including all available commitments thereunder) of more
     than $10,000,000;
 
          (vi) Permitted Purchase Money Debt;
 
          (vii) any additional Debt issued in payment of interest on any Debt;
     provided that the Debt being issued in payment of interest is of like tenor
     and terms as the Debt on which it is paid;
 
          (viii) any Margin Debt incurred in connection with investments
     permitted by clause (vii) of the covenant described under the caption
     "Restrictions on Investments, Loans and Advances" below; and
 
          (ix) Debt incurred by the Obligors other than pursuant to clauses (i)
     through and including (viii) of this covenant; provided that (1) the
     aggregate principal amount of such Debt at any time outstanding shall not
     exceed $10,000,000 and (2) such Debt shall be Subordinated Debt.
 
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<PAGE>   62
 
CHANGE IN CONTROL
 
     The Secured Indenture requires the Obligors (or their successors in the
event a Change in Control occurs pursuant to a transaction permitted by the
covenant described under the caption "Merger, Consolidation and Sale of Assets"
below) to make an offer to purchase all of the Secured Notes on the 90th day
following the date on which a Change in Control occurs, at a price equal to 101%
of the Accreted Value thereof as of the payment date plus accrued but unpaid
interest thereon to the payment date, if such date is after June 30, 1995. This
provision could have the effect of deterring or delaying a change in control of
the Company. In connection with any such offer, the Obligors would comply with
all applicable tender offer rules, including without limitation, Section 14(e)
of the Exchange Act and the rules promulgated thereunder and any other then
applicable regulatory requirements.
 
     The Credit Agreement prohibits the Obligors from redeeming, purchasing or
otherwise acquiring any of the Secured Notes or other subordinated debt,
provided, however, that, notwithstanding the foregoing, if no default under the
Credit Agreement has occurred and is continuing immediately prior to and after
giving effect to such a redemption, purchase or other acquisition, Mesa may
redeem, or otherwise acquire, such Secured Notes and subordinated debt (i)
through the application of the net proceeds from the issuance or sale of certain
refinancing debt or of equity securities of Mesa or (ii) in an amount not to
exceed $75,000,000 (in addition to amounts permitted by clause (i) above) after
the aggregate commitment of the banks is equal to or less than $50 million and
either Mesa has prevailed at trial in the Unocal lawsuit (as described herein)
or such lawsuit has otherwise been resolved, settled or terminated. See
"Business -- Legal Proceedings." The Credit Agreement also provides that certain
change of control events of the Company would constitute a default thereunder.
Any future credit agreements or other agreements relating to First Lien Debt to
which the Company or MOC becomes a party may contain similar restrictions and
provisions. In the event a Change in Control occurs at a time when the Obligors
are prohibited from purchasing the Secured Notes, the Obligors could seek the
consent of their lenders to the purchase of the Secured Notes or could attempt
to refinance the borrowings that contain such prohibition. If the Obligors did
not obtain such a consent or repay such borrowings, the Obligors would remain
prohibited from purchasing the Secured Notes. In such case, the Obligors'
failure to purchase tendered Secured Notes would constitute an Event of Default
under the Secured Indenture. In such circumstances, the subordination provisions
in the Secured Indenture would likely restrict payments to the holders of the
Secured Notes.
 
RESTRICTIONS ON ACTIVITIES OF CAPITAL
 
     The Secured Indenture provides that Capital may not engage in any business
not related directly or indirectly to the incurrence of Debt outstanding on May
1, 1993 or permitted by the Secured Indenture. In addition, the Secured
Indenture provides that Capital may not create or otherwise acquire any
subsidiary.
 
TRANSACTIONS WITH AFFILIATES
 
     The Secured Indenture provides that the Obligors will not, and will not
permit any subsidiary of the Company to, (i) sell, lease, exchange, swap,
transfer or otherwise dispose of any of their respective properties, assets or
securities to, (ii) purchase or lease any property, assets or securities from,
(iii) make any investment in, or (iv) enter into any contract or agreement with
or for the benefit of, an affiliate (an "Affiliate Transaction"), other than
Affiliate Transactions which the board of directors of the Company reasonably
and in good faith determines (a) are on terms at least as favorable to the
Obligor or the subsidiary contemplating such Affiliate Transaction as could be
obtained from an unaffiliated party or (b) in the event no comparable
transaction with an unaffiliated third party is available, on terms that are
fair from a financial point of view to such Obligor or subsidiary, as the case
may be, (but in respect of any such Affiliate Transaction or series or related
Affiliate Transactions involving an amount, or consideration having a fair
value, in excess of $1,000,000, only with the concurrence in such determination
of a majority of the Disinterested Directors who are not also employees,
officers, directors, partners or otherwise affiliated with any other party to
such transaction); provided, however, that this covenant shall not limit, or be
applicable to, (A) any allocation, reimbursement, indemnification or other
payment paid or accrued to, or transaction with, an affiliate pursuant to the
agreement of limited partnership of any subsidiary of the Company that is a
partnership, (B) the use or leasing by any affiliate of any property (including,
but not limited to, office equipment, computers, vehicles, aircraft and office
space) of any Obligor or any subsidiary of the Company if such Obligor or
subsidiary is
 
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<PAGE>   63
 
reimbursed based on the incremental cost to such Obligor or subsidiary of such
usage or (C) any indemnification or similar payment made to any director or
officer (1) in accordance with the corporate charter or bylaws of the Company or
any subsidiary, (2) under any agreement or (3) under applicable law.
 
RESTRICTIONS ON INVESTMENTS, LOANS AND ADVANCES
 
     The Secured Indenture provides that the Obligors may not, and may not
permit any of their Qualified Subsidiaries to, make or permit to exist any
loans, advances or capital contributions to, or make any investment in, or
purchase or commit to purchase any stock or other securities of (including
evidences of indebtedness of or other interests in), any person, other than (i)
as shown on Schedule 2 to the Secured Indenture ("Existing Loans and Advances"),
subject to reduction pursuant to the covenant described under the caption
"Repayment of Intercompany Debt" below; (ii) Permitted Investments; (iii) loans,
advances or capital contributions to HCLP, (1) to the extent necessary for HCLP
to avoid any default on the HCLP Secured Notes or to permit HCLP to make
payments, which if not made, would result in the imposition of any premiums or
other penalties on the HCLP Secured Notes plus (2) in an aggregate amount during
any fiscal year equal to such amount of loans, advances or capital contributions
as shall be made during such year as a Restricted Payment pursuant to and in
accordance with the covenant described under the caption "Limitation on
Restricted Payments;" (iv) loans, advances or capital contributions to
Non-Qualified Subsidiaries other than HCLP in an aggregate amount during any
fiscal year less than or equal to the sum of (1) $4,000,000 plus (2) such
amount, if any, as shall be made during such year as a Restricted Payment
pursuant to and in accordance with the covenant described under the caption
"Limitation on Restricted Payments;" (v) current trade and customer accounts
receivable that are for goods furnished or services rendered in the ordinary
course of business and are payable in accordance with customary trade terms;
(vi) Energy Futures Contracts acquired or entered into for hedging purposes;
(vii) Energy Futures Contracts acquired or entered into for purposes other than
hedging, and stocks or other securities (but not including (a) uncovered short
sales of individual securities, and (b) uncovered put or call options on
individual securities or which relate to securities indices) other than those
permitted pursuant to clauses (i) through (vi) above, provided that the sum of
the aggregate amount on deposit in respect of such Energy Futures Contracts plus
amounts on deposit to collateralize obligations to purchase securities in the
future pursuant to short sales plus the aggregate cost of such stocks or other
securities, shall not exceed, at any one time outstanding, the sum of
$25,000,000 plus 100% of the aggregate profits realized on all such investments
after June 30, 1993 minus 100% of the aggregate losses realized on all such
investments after June 30, 1993; and (viii) loans, advances or capital
contributions to Qualified Subsidiaries made in the ordinary course of business
to meet reasonable working capital requirements, provided that the principal
purpose of each of such loans, advances or capital contributions is not to favor
any person (other than such Qualified Subsidiary) over the holders of the
Secured Notes.
 
LIMITATIONS ON ACQUISITIONS
 
     The Secured Indenture provides that the Obligors may not acquire, and shall
not permit any Qualified Subsidiary to acquire (whether by merger,
consolidation, purchase of assets, purchase of capital stock, or other business
combination), any other person that is not engaged in a business (or aspect
thereof) in which the Company or any of its subsidiaries was engaged as of May
1, 1993.
 
REPAYMENT OF INTERCOMPANY DEBT
 
     The Secured Indenture provides that on or before the earlier of (i) the
date of issuance of any additional Secured Notes in accordance with the Secured
Indenture (i.e., the Secured Notes being offered hereby) and (ii) January 1,
1995, (x) MHC shall, to the extent it has assets sufficient to do so, repay its
Debt to MOC and (y) MMC shall, to the extent it has assets sufficient to do so,
repay its Debt to MOC; provided, however, that notwithstanding the foregoing,
each of MHC and MMC shall be required to repay its respective Debt to MOC
pursuant to this covenant only to the extent that its respective Debt to MOC
exceeds $5,000,000. For purposes of this covenant, each 1% limited partnership
interest in HCLP shall be valued at $5,000,000 and other non-cash assets shall
be valued at book value. Mesa intends to cause MMC and MHC to repay their
intercompany debt as required by the Secured Indenture prior to completion of
this Offering.
 
     Prior to the date on which it has reduced the balance of its respective
Debt to MOC to an amount not in excess of $5,000,000, MHC and MMC, respectively,
shall not engage in any business activity other than
 
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<PAGE>   64
 
(i) owning and operating the assets it currently owns or (ii) making any
investment or effecting any transaction permitted by the covenant described
under the caption "Restrictions on Investments, Loans and Advances" above.
 
RESTRICTION ON CHANGES IN BUSINESS
 
     The Secured Indenture provides that neither the Company nor MOC may engage
in the conduct of any business other than the Oil and Gas Business; provided,
however, that, nothing in this covenant shall be deemed to prohibit the Company
or MOC from acquiring, owning or controlling, at any time, any equity interest
in any other person, provided that such acquisition, ownership or control is not
prohibited by the terms hereof.
 
     "Oil and Gas Business" means (i) the acquisition, exploration, development,
operation and disposition of interests in oil, gas and other hydrocarbon
properties, (ii) the gathering, marketing, treating, processing, selling and
transporting of any production from such interests or properties, (iii) any
business relating to or arising from exploration for or development, production,
treatment, processing, transportation or marketing of oil, gas and other
minerals and products produced in association therewith, and (iv) any activity
necessary, appropriate or incidental to the activities described in the
foregoing clauses (i) through (iii) of this definition.
 
LIMITATION ON COMPENSATION OF EXECUTIVE OFFICERS
 
     The Obligors shall not, and shall not permit any subsidiary to, (a) make,
or incur or otherwise accrue any obligation to make, during any year, any
payment, in cash or other assets, of salary or bonus compensation to any
executive officer of any Obligor unless the aggregate amount of such payments
and accruals to such officer in such year (i) has been determined to be
reasonable and appropriate by the board of directors of the Company, with the
concurrence in such determination of a majority of the Disinterested Directors,
or by a committee consisting of Disinterested Directors and (ii) would not
exceed $2,000,000, if such year is 1993, 1994 or 1995, or the product of
$2,000,000 and the COLA Percentage for such year, if such year is 1996 or a
subsequent year, (b) make any payment, in cash or other assets, of salary or
bonus compensation to any such officer during any year, if the aggregate amount
of such payments to such officer in such year would exceed $980,000, if such
year is 1993, 1994 or 1995, or the product of $980,000 and the COLA Percentage
for such year if such year is 1996 or a subsequent year, or (c) make, during any
year, any payment to any such officer of any obligation accrued during any prior
year for salary or bonus compensation, unless (x) the year of such payment is
1996 or a subsequent year and (y) at the time of such payment the Obligors are
permitted by the terms of the first sentence of the covenant described under the
caption "Limitation on Restricted Payments" above to make or pay a Restricted
Payment equal to or greater than the amount of such payment; provided that
clause (a) (ii) above shall not restrict the amount of any payment or accrual,
if at the time of such payment or accrual, no Unsecured Notes are outstanding
and the Obligors are permitted by the terms of the first sentence of the
covenant described under the caption "Limitation on Restricted Payments" above
to make or pay a Restricted Payment equal to or greater than the amount of such
payment or accrual; and, provided further that the amount of any payment made
during any year of any obligation accrued during a prior year shall not be
subject to clause (a) or clause (b) above, if such payment is not prohibited by
clause (c) above. "COLA Percentage" for any year means the greater of (i) 100%
and (ii) the quotient (expressed as a percentage) of (i) the United States
Department of Labor's U.S. Consumer Price Index-All Items (All Urban Consumers)
at December 31 of the year immediately preceding such year divided by (ii) such
index at May 1, 1993.
 
RATING OF SECURITIES; LISTING
 
     In the Secured Indenture, the Obligors agreed to use reasonable efforts to
cause (a) the Secured Notes to be rated by Standard & Poor's Corporation, (b)
Standard & Poor's Corporation to continue rating the Secured Notes at all times
and (c) the Secured Notes to be listed on a national securities exchange. Mesa
does not currently meet the listing requirements for the listing of the Secured
Notes on the New York Stock Exchange.
 
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<PAGE>   65
 
MERGER, CONSOLIDATION AND SALE OF ASSETS
 
     The Secured Indenture provides that neither the Company nor MOC may
consolidate with, merge into or sell, lease or transfer all or substantially all
of its respective assets as an entirety to any person unless (a) the successor,
which may be a corporation, a partnership, a business association or a trust
organized and existing under the laws of the United States or any State thereof
or the District of Columbia, expressly assumes the obligations of the Company or
MOC under the Secured Indenture and the Secured Notes, (b) immediately before
and immediately after giving effect to such transaction, no Event of Default,
and no event which is, or after notice or passage of time or both, would become
an Event of Default, shall have occurred and be continuing and (c) if the other
party to the transaction has outstanding any Debt immediately prior to such
transaction, the successor person could, immediately after giving effect to such
transaction on a pro forma basis, incur at least $1.00 of additional Debt in
accordance with the covenant described under the caption "Limitation on
Incurrence of Other Debt;" provided, however, that the foregoing provisions
shall not prevent MOC from consolidating with, merging into, or selling, leasing
or transferring all or substantially all of its assets as an entirety to the
Company provided that the conditions in clauses (a) and (b) above are satisfied.
The Secured Indenture provides that Capital may not consolidate with, merge into
or sell, lease or transfer all or substantially all of its assets as an entirety
to any person unless (i) the resulting, surviving or transferee person is the
Company or MOC or a corporation organized and existing under the laws of the
United States or any State thereof or the District of Columbia that is a wholly
owned Qualified Subsidiary and expressly assumes the obligations of Capital
under the Secured Indenture and the Secured Notes and (ii) immediately before
and immediately after giving effect to such transaction, no Event of Default,
and no event which is, or, after notice or passage of time or both, would become
an Event of Default, shall have occurred and be continuing. Notwithstanding the
foregoing, MOC may consolidate with, merge into or transfer all or part of its
assets to the Company, and any Qualified Subsidiary other than MOC and Capital
may consolidate with, merge into or sell, lease or transfer all or part of its
assets to the Company or any other Qualified Subsidiaries.
 
DEFEASANCE
 
     So long as no Senior Debt Default exists or would result therefrom, the
Obligors may terminate their obligations under the Secured Indenture at any time
by delivering all outstanding Secured Notes to the Secured Trustee for
cancellation. So long as no Senior Debt Default exists or would result
therefrom, the Obligors may, subject to certain conditions, also terminate all
of their obligations under the Secured Indenture, other than their obligations
in respect of payment of principal of and interest on the Secured Notes issued
thereunder, at any time by depositing in trust with the Secured Trustee or a
paying agent other than the Obligors money, non-callable U.S. Government
obligations or beneficial interests in one or more mutual funds which invest
solely in U.S. Government obligations and which are rated in the highest
applicable rating category by a nationally recognized statistical rating
organization, in each case in an amount sufficient to pay all remaining
indebtedness on the Secured Notes.
 
MODIFICATION AND WAIVER
 
     Amendments and supplements to the Secured Indenture may be made by the
Obligors and the Secured Trustee with the written consent of a Requisite
Majority of the outstanding Secured Notes; provided that no such amendment or
supplement may, without the consent of the holder of each Secured Note affected
thereby, (i) reduce the percentage of the aggregate face amount of the Secured
Notes necessary to modify, amend or waive any provision of the Secured Indenture
or the Secured Notes; (ii) reduce the rate or change the time for payment of
interest on any Secured Note; (iii) reduce the face amount of or change the
fixed maturity of any Secured Note or portion thereof payable on acceleration
prior to maturity or alter the redemption provisions with respect thereto; (iv)
waive a default in the payment of principal of, interest on or redemption
payment or payment upon mandatory retirement of or a Change in Control with
respect to any Secured Note; (v) impair the right to institute suit for the
enforcement of any payment on or with respect to any Secured Note; (vi) make any
Secured Note payable in a currency other than that stated therein; (vii) amend
the definition of "Accreted Value" in the Secured Indenture or the application
of such term in connection with redemptions or repurchases of Secured Notes or
(viii) modify the subordination provisions of the Secured Indenture in a manner
adverse to the holders of the Secured Notes. Subject to the foregoing, a
Requisite Majority of the outstanding Secured Notes may waive certain past
defaults and may waive
 
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<PAGE>   66
 
compliance by any or all of the Obligors with the covenants described above
without notice to any other holder. An amendment to the Secured Indenture may
not adversely affect the rights under the subordination provisions thereof of
the holders of any issue of Senior Debt of any Obligor without the consent of
such holders. In addition, the Obligors and the Secured Trustee may modify and
amend the Secured Indenture without the consent of any holder in order to cure
ambiguities or to make certain other changes that will not affect adversely the
rights of any holder.
 
EVENTS OF DEFAULT AND NOTICE THEREOF
 
     The term "Event of Default" when used in the Secured Indenture means any
one of the following: (i) failure to pay interest on the Secured Notes for 30
days, principal of Secured Notes when due or payments to redeem or purchase the
Secured Notes as described under "-- Mandatory Retirement" or "-- Change in
Control" above (in each case regardless of whether such payment is prohibited by
the subordination provisions of the Secured Indenture); (ii) failure of any
Obligor to perform any of its other covenants after notice and a grace period;
(iii) occurrence and continuation beyond any applicable grace period of any
payment default on, or any other default causing (or, in the case of the Company
or MOC, permitting) acceleration of, any indebtedness of any Obligor or a
significant subsidiary of the Company for money borrowed, including under the
Indenture for the Unsecured Notes (provided, in the case of the Company or MOC,
that the aggregate principal amount of such indebtedness shall exceed $10
million); provided that, if any such default is cured or waived and any such
acceleration rescinded, or such debt is repaid, such Event of Default under the
Secured Indenture and any consequent acceleration of the Secured Notes shall be
automatically rescinded, so long as such rescission does not conflict with any
judgment or decree; (iv) the rendering against any Obligor or any significant
subsidiary of the Company of (a) final judgments for the payment of an aggregate
amount exceeding $10 million that remain undischarged for a period (during which
execution thereof shall not be effectively stayed) of 60 days after the date on
which any period for appeal has expired or (b) final judgments, individually or
in the aggregate, in an amount of $10 million or more that shall remain
undischarged and in respect of which judgment liens shall have been perfected on
a substantial portion of the assets of the Obligors or any portion of the
Collateral; and (v) occurrence of certain events of bankruptcy, insolvency or
reorganization with respect to any Obligor or any significant subsidiary of the
Company.
 
     The Secured Indenture provides that the Secured Trustee shall, within 30
days after the occurrence of any default (the term "default" to include the
events specified above without grace or notice) known to it, give to the holders
of the Secured Notes notice of such default, provided that, except in the case
of a payment default with respect to any of the Secured Notes, the Secured
Trustee shall be protected in withholding such notice if it in good faith
determines that the withholding of such notice is in the interest of the holders
of the Secured Notes. The Secured Indenture requires the Obligors to certify to
the Secured Trustee quarterly as to whether any default occurred during such
quarter.
 
     In case an Event of Default (other than an Event of Default resulting from
the bankruptcy, insolvency or reorganization of an Obligor) shall occur and be
continuing under the Secured Indenture, the Secured Trustee or the holders of at
least 25% in aggregate face amount (at maturity) of the Secured Notes then
outstanding, by notice in writing to the Obligors (and to the Secured Trustee if
given by the holders of the Secured Notes), may declare the Stated Price of the
Secured Notes then outstanding to be due and payable immediately. In case an
Event of Default resulting from certain events of bankruptcy, insolvency or
reorganization of an Obligor shall occur, the Stated Price of the Secured Notes
then outstanding shall become due and payable immediately without any
declaration or other act on the part of the Secured Trustee or the holders of
the Secured Notes. Such acceleration may be annulled and past defaults (except,
unless theretofore cured, a default in payment of the Stated Price of or
interest on the Secured Notes) may be waived by the holders of a Requisite
Majority, upon the conditions to be provided in the Secured Indenture.
 
     The Secured Indenture provides that no holder of a Secured Note may pursue
any remedy under the Secured Indenture unless the Secured Trustee shall have
failed to act for a period of 60 days after notice to the Secured Trustee of an
Event of Default, receipt by the Secured Trustee of a request from holders of at
least 25% in face amount (at maturity) of the Secured Notes to pursue such
remedy and the offer to the Secured Trustee of indemnity satisfactory to it;
however, such provision does not affect the right of a holder of the Secured
Notes to sue for enforcement of any overdue payment thereon.
 
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<PAGE>   67
 
REPORTS TO SECURITYHOLDERS
 
     Each Obligor shall file with the Trustee copies of its annual reports and
of the information, documents and other reports which it is required to file
with the SEC under the Exchange Act. If Mesa is not a reporting company under
the Exchange Act, it shall file with the Trustee financial statements and a
"Management's Discussion and Analysis of Financial Condition and Results of
Operations," each comparable to that which Mesa would have been required to file
with the SEC if it were a reporting company under the Exchange Act. For so long
as the Secured Notes remain outstanding, Mesa will mail or cause to be mailed
copies of all such documents and reports to the holders of the Secured Notes.
 
THE SECURED TRUSTEE
 
     Harris Trust and Savings Bank is the trustee and collateral agent under the
Secured Indenture and the Security Instruments. The Secured Indenture contains
certain limitations on the right of the Secured Trustee, as a creditor of the
Obligors, to obtain payment of claims in certain cases, or to realize on certain
property received in respect of any such claim as security or otherwise. The
Secured Trustee is permitted to engage in other transactions; however, if it
acquires any conflicting interest (as defined), it must eliminate such conflict
or resign.
 
     The holders of a majority in principal amount or face amount (at maturity),
as applicable, of all outstanding Secured Notes shall have the right to direct
the time, method and place of conducting any proceeding for any remedy or
exercising any power available to the Secured Trustee under the Secured
Indenture.
 
GOVERNING LAW
 
     The Secured Indenture and the Secured Notes provide that they will be
governed by the laws of the State of New York.
 
CERTAIN DEFINITIONS USED IN THE SECURED INDENTURE
 
     "Accreted Value" with respect to any Secured Note means, as of May 1, 1993,
76.506% of the stated principal amount of such Secured Note, and as of any date
after May 1, 1993 and prior to July 1, 1995 as of which the Accreted Value is
being calculated (the "Calculation Date"), (a) if the Calculation Date is prior
to June 30, 1993, an amount equal to the sum of (i) the Accreted Value of such
Secured Note as of May 1, 1993 plus (ii) the accrued amortization of the
original issue discount from (but excluding) May 1, 1993 to (and including) the
Calculation Date, calculated as the product of (x) 2.0814% of the Accreted Value
of such Secured Note as of May 1, 1993 and (y) a fraction, the numerator of
which is the number of days from (but excluding) May 1, 1993 to (and including)
the Calculation Date (assuming a 360-day year of twelve 30-day months), and the
denominator of which is 60 or (b) if the Calculation Date is a June 30 or
December 31, the percentage of the stated principal amount of such Secured Note
as of such date as shown in the table below or (c) if the Calculation Date is
not a June 30 or December 31, an amount equal to the sum of (i) the Accreted
Value of such Secured Note as of the then most recent to have occurred of the
June 30 or December 31, as the case may be, immediately preceding the
Calculation Date plus (ii) the accrued amortization of the original issue
discount from (but excluding) such immediately preceding June 30 or December 31
to (and including) the Calculation Date, calculated as the product of (x) 6.375%
of the Accreted Value of the Secured Note as of such immediately preceding June
30 or December 31 and (y) a fraction, the numerator of which is the number of
days from (but excluding) such immediately preceding June 30 or December 31 to
(and including) the Calculation Date (assuming a 360-day year of twelve 30-day
months), and the denominator of which is 180. The Accreted Value of each Secured
Note as of each June 30 and December 31 prior to July 1, 1995 shall be an amount
in dollars equal to a percentage of the face amount (at maturity) of such
Secured Note as set forth below:
 
<TABLE>
<CAPTION>
                                                               JUNE 30      DECEMBER 31
                                                               --------     -----------
        <S>                                                    <C>          <C>
        1993.................................................   78.098%       83.077%
        1994.................................................   88.373%       94.007%
        1995.................................................  100.000%
</TABLE>
 
                                       65
<PAGE>   68
 
On and after June 30, 1995, the Accreted Value of each Secured Note shall be
equal to 100% of the stated principal amount thereof.
 
     "Applicable Amount of Secured Notes" means, with respect to a Mandatory
Retirement Date under the Secured Indenture, (i) if such Mandatory Retirement
Date is on or prior to June 30, 1995, Secured Notes having, as of such Mandatory
Retirement Date, an aggregate Accreted Value equal to the amount of Mandatory
Retirement Funds as of the corresponding Mandatory Retirement Notice Date, or
(ii) if such Mandatory Retirement Date is on or after July 1, 1995, Secured
Notes having an aggregate face amount (at maturity) equal to the excess of (x)
the amount of Mandatory Retirement Funds as of the corresponding Mandatory
Retirement Notice Date over (y) the aggregate amount of accrued but unpaid
interest on the Secured Notes to the applicable Mandatory Retirement Date.
 
     "Base EBITDA" means (a) for the one-year period ending June 30, 1994, the
sum of the Quarterly Base EBITDA amounts with respect to each of the calendar
quarters comprising such period, and (b) for the two-year period ending June 30,
1995, the sum of the Quarterly Base EBITDA amounts with respect to each of the
calendar quarters comprising such period.
 
     "Bicoastal Collections" means any distributions to the Obligors or any of
their subsidiaries pursuant to that certain Amended and Restated Plan of
Reorganization dated as of June 2, 1992, as modified by the Modification to
Amended and Restated Plan of Reorganization of Bicoastal Corporation, dated
August 27, 1992, as confirmed by an order dated September 14, 1992 entered
pursuant to 11 U.S.C. sec.1129 by the United States Bankruptcy Court, Middle
District of Florida, Tampa Division, and any amendments or modifications
thereto.
 
     "Cash Flow" of any person means, for any period, the sum (without
duplication) for such person and its subsidiaries on a consolidated basis of the
following for such period: (i) operating income (loss) before minority interest
and extraordinary items, (ii) depreciation, depletion and amortization expense,
(iii) impairment and abandonment expense, and (iv) other non-cash items
decreasing operating income, less other non-cash items increasing operating
income.
 
     "Cash Flow Coverage Ratio" means the ratio of (i) the sum of Designated
Cash Flow (as defined below) plus Net Interest Expense (as defined below) for
the latest period of four full fiscal quarters for which financial information
is available immediately prior to the date of the transaction giving rise to the
need to calculate the Cash Flow Coverage Ratio to (ii) Net Interest Expense for
such period of four full fiscal quarters, in each case determined on a pro forma
basis as if such transaction (including the incurrence of such Debt, and all
other Debt incurred after the end of such period of four full fiscal quarters
and on or prior to the date of such transaction, and the application of the
proceeds therefrom) had been consummated at the beginning of such period.
 
     "Cash Proceeds" means, with respect to a Collateral Sale, the amount of
cash received by the Company or MOC in connection with such Collateral Sale,
less (i) all sales, transfer, income and other taxes payable as a result of such
Collateral Sale, and (ii) the out-of-pocket expenses incurred in connection with
or as a result of such sale.
 
     "Change in Control" is defined as the acquisition by any person (together
with its affiliates), in one or more transactions, of beneficial ownership of
50% or more in voting power of the outstanding capital stock of the Company. For
purposes of the definition, "beneficial ownership" of securities includes,
without limitation, the right to vote or direct the vote of, or the right to
dispose or direct the disposition of, such securities.
 
     "Collateral Account" means a custodial account maintained by the Secured
Trustee, as collateral agent, for the benefit of the holders of Secured Notes,
into which Release Amounts with respect to Collateral Sales are deposited
pursuant to the Secured Indenture or any of the Security Instruments and, under
certain circumstances, insurance proceeds in respect of West Panhandle
Collateral are to be transferred pursuant to the Mortgage.
 
     "Collateral Sale" means a sale, assignment, lease, transfer, conveyance or
other disposition of any of the Collateral.
 
     "Consolidated Debt" means, for any date, the amount of Debt of the Company
and its Qualified Subsidiaries as of such date, determined on a consolidated
basis in accordance with GAAP.
 
                                       66
<PAGE>   69
 
     "Consolidated Net Income" of any person means, for any period, the
aggregate net income (or loss) of such person and its subsidiaries for such
period on a consolidated basis, determined in accordance with GAAP, provided
that (a) the net income or loss of any other person in which such person or any
subsidiary thereof has an interest (which interest does not cause the net income
of such other person to be consolidated with the net income of such person in
accordance with GAAP) shall be excluded and instead an amount equal to any
dividends or distributions paid to such person or its subsidiaries by such other
person in such period shall be included and (b) the net income (or loss) of any
other person acquired in a pooling of interest transaction for any period prior
to the date of such acquisition shall be excluded.
 
     "D&M Report" means the reserve report dated December 31, 1992 prepared by
DeGolyer and MacNaughton, independent petroleum consultants, with respect to
Properties that include the West Panhandle Collateral.
 
     "Debt" of an entity is defined as the following, whether outstanding on the
date of the Secured Indenture or thereafter created or incurred: (a) any
liability of such entity (1) for borrowed money, (2) evidenced by a note,
debenture or similar instrument (including a purchase money obligation) given in
connection with the acquisition of or exchange for any property or assets (other
than inventory or similar property acquired in the ordinary course of business),
including securities and Debt, or (3) in respect of letters of credit issued for
its account; (b) any liability of others described in clause (a) that such
entity has guaranteed or which is otherwise its legal liability or which is
secured by assets of such person; (c) any amendment, renewal, extension or
refunding of any liability of the types referred to in the preceding clauses (a)
and (b); and (d) in the case of the Company, any preferred stock of any
Qualified Subsidiary (as defined under "Mandatory Retirement" below), except for
preferred stock issued to the Company or any other Qualified Subsidiary;
provided that "Debt" of an entity shall not include any liability of such entity
for employee compensation or for inventory or similar property acquired in the
ordinary course of business or for services.
 
     "Designated Cash Flow" means, for any period, Cash Flow of the Company and
its subsidiaries on a consolidated basis, determined in accordance with GAAP,
for such period, less (a) HCLP Required Cash Flow for such period, less (b) Cash
Flow of any other Non-Qualified Subsidiary of the Company for such period, less
(c) any equity contributions, advances or loans to any Non-Qualified Subsidiary
made during such period and plus (d) cash actually distributed, advanced or
loaned by a Non-Qualified Subsidiary to the Company or to any Qualified
Subsidiary during such period.
 
     "Disinterested Directors" of the Company means members of the board of
directors of the Company who are not employees, officers or affiliates (or
employees, officers or general partners of such affiliates) of the Company;
provided, however, that for the purposes of this definition, no person shall be
deemed to be an affiliate of the Company solely because such person is a member
of the board of directors of the Company.
 
     "Energy Futures Contracts" means energy futures and other contracts,
options, forward pricing or sale arrangements or other energy related derivative
securities.
 
     "Equity Securities" of the Company means capital stock or other equity
interests in the Company or warrants, options or other rights to acquire capital
stock or other equity interests in the Company (but excluding, prior to its
conversion or exchange, any debt security (excluding the Convertible Notes) that
is convertible into, or exchangeable for, capital stock).
 
     "Excess Sale Proceeds" for any period, means the excess of (i) 50% of the
sum of (x) the aggregate net cash proceeds received during such period from the
sale by the Company or any of its Qualified Subsidiaries during such period of
any oil and gas properties (other than West Panhandle Collateral or any
partnership interest in HCLP) plus (y) Bicoastal Collections received by the
Company or any of its subsidiaries during such period over (ii) the amount of
such net cash proceeds and Bicoastal Collections applied during such period to
repay or retire Debt outstanding under the Credit Agreement.
 
     "First Lien Debt" means any obligations (including, without limitation, any
obligations payable under the Credit Agreement) secured by a lien upon or
security interest in the Collateral, which lien or security interest is senior
or prior to the liens and security interests created by the Mortgage and the
Pledge Agreement.
 
     "Forward Sale" means any advance payment agreement or other arrangement
pursuant to which Operating, having received full payment of the purchase price
for a specified quantity of Hydrocarbons upon
 
                                       67
<PAGE>   70
 
entering such agreement or arrangement, is required to deliver, in one or more
installments subsequent to the date of such agreement or arrangement, such
quantity of Hydrocarbons to the purchaser of such Hydrocarbons pursuant to and
during the term of such agreement or arrangement.
 
     "Fractional Sale" means a sale of an undivided percentage interest in the
assets sold pursuant to such sale.
 
     "GAAP" means generally accepted accounting principles as in effect in the
United States of America as of any date of determination.
 
     "HCLP Required Cash Flow" means, for any period, Cash Flow of HCLP for such
period that is not permitted by the terms of the mortgage securing the HCLP
Secured Notes to be distributed by HCLP free of the lien of such mortgage.
 
     "Helium" means any interest in helium processed at MOC's Satanta Plant, as
shown in the most recent Reserve Report that includes all such Helium.
 
     "Helium EBITDA Reduction Percentage" means, with respect to a reduction of
Helium Quarterly Base EBITDA amounts resulting from a Forward Sale of Helium,
the quotient (stated as a percentage) of (a) the Reduction Percentage Numerator
and (b) the Reduction Percentage Denominator. For purposes of this definition
(a) "Reduction Percentage Numerator" means the volume of Helium deliverable
pursuant such sale and (b) "Reduction Percentage Denominator" means the total
volume of Helium owned by MOC.
 
     "Helium Quarterly Base EBITDA" means, with respect to any calendar quarter
set forth below, the amount, in dollars, set forth below opposite such calendar
quarter; provided, that upon each Forward Sale by MOC of any Helium after June
30, 1993, Helium Quarterly Base EBITDA with respect to any calendar quarter
beginning after the date of such sale, shall be an amount equal to the product
of (a) the Helium Quarterly Base EBITDA amount in effect immediately prior to
such sale with respect to such calendar quarter and (b) the excess of (i) 100%
over (ii) the Helium EBITDA Reduction Percentage with respect to such sale.
 
<TABLE>
<CAPTION>
                                                                              HELIUM
                                                                            ----------
        <S>                                                                 <C>
        September 30, 1993................................................     910,000
        December 31, 1993.................................................   1,596,000
        March 31, 1994....................................................   2,053,000
        June 30, 1994.....................................................     225,000
        September 30, 1994................................................   1,517,000
        December 31, 1994.................................................   2,659,000
        March 31, 1995....................................................   2,864,000
        June 30, 1995.....................................................     314,000
</TABLE>
 
     "Hydrocarbons" has the meaning given to such term in the Mortgage.
 
     "Independent Financial Advisor" means an accounting, appraisal or
investment banking firm of nationally recognized standing which is qualified to
perform the task for which such firm has been engaged and is independent with
respect to the Obligors.
 
     "Interest Expense" means, for any person for any period, interest expense
of such person for such period, including the amortization of original issue
discount and the interest component of any capitalized lease obligation, less,
to the extent included in such interest expense, amortization of costs incurred
in connection with the issuance of Debt of such person and interest paid or to
be paid in capital stock of such person.
 
     "Interest Income" means, for any person for any period, interest and
dividend income of such person for such period, and dividend income includes
distributions, to the extent of current accumulated earnings, on equity
investments (other than in subsidiaries).
 
     "Mandatory Retirement Date" means, when used with respect to a Mandatory
Retirement Notice Date, a date selected by the Obligors that is not less than 30
nor more than 40 days after such Mandatory Retirement Notice Date.
 
                                       68
<PAGE>   71
 
     "Mandatory Retirement Funds" means, as of any Mandatory Retirement Notice
Date, an amount equal to 90% of the excess of the sum of (a) Cash Flow of the
Company for the period beginning July 1, 1993 and ending on the June 30 prior to
such Mandatory Retirement Notice Date plus (b) if no Debt is outstanding under
the Credit Agreement on such June 30, any Excess Sale Proceeds for such period,
over the sum of (i) Senior Debt Retirement for such period, (ii) Permitted
Capital Expenditures for such period, (iii) Base EBITDA for such period, (iv)
Qualified Interest Expense for such period and (v) Cash Flow of Non-Qualified
Subsidiaries for such period; provided that Mandatory Retirement Funds as of
such Mandatory Retirement Notice Date shall not exceed the excess of (i) the
change from May 1, 1993 to such June 30 in the aggregate Accreted Value of the
Secured Notes then outstanding plus the change from May 1, 1993 to such June 30
in the aggregate Accreted Value (as defined in the Indenture for the Unsecured
Notes) of the Unsecured Notes then outstanding over (ii) the aggregate amount of
the Accreted Value of Secured Notes redeemed, repurchased or otherwise acquired
prior to such Mandatory Retirement Notice Date (such Accreted Value to be
determined as of the date of such redemption, repurchase or other acquisition),
plus the aggregate amount of the Accreted Value (as defined in the Indenture for
the Unsecured Notes) of Unsecured Notes (x) redeemed, repurchased or otherwise
acquired prior to such Mandatory Retirement Notice Date or (y) required to be
acquired on such Mandatory Retirement Date pursuant to the indenture for the
Unsecured Notes (such Accreted Value to be determined, in each case, as of the
date of such redemption, repurchase or other acquisition) plus any amounts made
available for purchases pursuant to any prior Retirement Offer to purchase
Secured Notes or any prior Retirement Offer (as defined in the indenture for the
Unsecured Notes) to purchase Unsecured Notes but not so applied because such
offer was undersubscribed.
 
     "Mandatory Retirement Notice Date" means August 31, 1994 or August 31,
1995.
 
     "Margin Debt" means Debt incurred to purchase or carry investments in
stocks or other securities permitted by the covenant described under the caption
"Restrictions on Investments, Loans and Advances" above.
 
     "Net Interest Expense" means, for any period, the excess of (i) Designated
Interest Expense for such period over (ii) Designated Interest Income for such
period. "Designated Interest Expense" means, for any period, Interest Expense of
the Company and its subsidiaries on a consolidated basis for such period,
determined in accordance with GAAP, less Interest Expense of HCLP and all other
Non-Qualified Subsidiaries for such period. "Designated Interest Income" means,
for any period, Interest Income of the Company and its subsidiaries on a
consolidated basis for such period, determined in accordance with GAAP, less any
Interest Income of HCLP and all other Non-Qualified Subsidiaries for such
period.
 
     "Non-Qualified Subsidiary" means HCLP and any subsidiary that at the time
of determination is designated as a Non-Qualified Subsidiary by the Company in
writing to the Secured Trustee (including each subsidiary of HCLP and of the
subsidiary so designated); provided, however, that neither MOC nor Capital may
be designated as a Non-Qualified Subsidiary and neither MHC nor MMC,
respectively, may be designated as a Non-Qualified Subsidiary prior to the date
on which it has reduced its respective Debt to MOC to an amount not in excess of
$5,000,000. Once a subsidiary has been designated a Non-Qualified Subsidiary,
the Company may not revoke such designation unless (a) immediately before and
immediately after giving effect to such revocation, no Event of Default, and no
event which is, or after notice or passage of time or both, would become an
Event of Default, shall have occurred and be continuing and (b) if such Non-
Qualified Subsidiary has outstanding any Debt immediately prior to such
revocation, the Company could, immediately after giving effect to such
revocation on a pro forma basis, incur at least $1.00 of additional Debt in
accordance with the covenant described under the caption "Limitation on
Incurrence of Debt" below. The Company has designated Mesa Environmental as a
Non-Qualified Subsidiary.
 
     "Non West Panhandle EBITDA Reduction Percentage" means, with respect to a
reduction of Non West Panhandle Quarterly Base EBITDA amounts resulting from a
sale of Non West Panhandle Property, the quotient (stated as a percentage) of
(a) the Reduction Percentage Numerator and (b) the Reduction Percentage
Denominator. For purposes of this definition (a) "Reduction Percentage
Numerator" means (i) if such sale of Non West Panhandle Property is an Oil and
Gas Property Sale, the volume of proved reserves of natural gas equivalents
attributable to the Properties sold pursuant to such sale, as specified in the
most recent Reserve Report that includes all reserves constituting the
Properties sold pursuant to such sale, or (ii) if such sale of Non West
Panhandle Property is a Forward Sale, the volume of natural gas equivalents
deliverable
 
                                       69
<PAGE>   72
 
pursuant to such sale on and after the first anniversary of the date of such
sale; and (b) "Reduction Percentage Denominator" means (i) if such sale of Non
West Panhandle Property is an Oil and Gas Property Sale, the total volume of
proved reserves of natural gas equivalents attributable to all of the Non West
Panhandle Property in the most recent Reserve Report that includes all of the
Non West Panhandle Property or (ii) if such sale of Non West Panhandle Property
is a Forward Sale, the total volume of proved reserves of natural gas
equivalents attributable to all of the Non West Panhandle Property in the most
recent Reserve Report that includes all of the Non West Panhandle Property.
 
     "Non West Panhandle Property" means any interest in any oil, gas or other
Hydrocarbon Property owned by MOC, except for (a) an interest in HCLP or (b) any
property comprising a portion of the West Panhandle Collateral.
 
     "Non West Panhandle Quarterly Base EBITDA" means, with respect to any
calendar quarter set forth below, the amount, in dollars, set forth below
opposite such calendar quarter; provided, that upon each sale by MOC of any Non
West Panhandle Property after June 30, 1993, Non West Panhandle Quarterly Base
EBITDA with respect to any calendar quarter beginning after the date of such
sale, shall be an amount equal to the product of (a) the Non West Panhandle
Quarterly Base EBITDA amount in effect immediately prior to such sale with
respect to such calendar quarter and (b) the excess of (i) 100% over (ii) the
Non West Panhandle EBITDA Reduction Percentage with respect to such sale.
 
<TABLE>
<CAPTION>
                                                                    NON WEST PANHANDLE
                                                                   QUARTERLY BASE EBITDA
                                                                   ---------------------
        <S>                                                        <C>
        September 30, 1993.......................................         5,840,000
        December 31, 1993........................................         8,420,000
        March 31, 1994...........................................        10,393,000
        June 30, 1994............................................         1,138,000
        September 30, 1994.......................................         7,677,000
        December 31, 1994........................................        13,459,000
        March 31, 1995...........................................         9,053,000
        June 30, 1995............................................           992,000
</TABLE>
 
     "Oil and Gas Property Sale" means a sale of Hydrocarbon reserves
attributable to a particular well or wells.
 
     "Permitted Capital Expenditures" for any period shall mean the aggregate
amount of capital expenditures by the Company and its Qualified Subsidiaries for
such period, provided that Permitted Capital Expenditures shall not exceed the
sum of (i) $28,000,000 for the one-year period ending June 30, 1994 or
$53,000,000 for the two-year period ending June 30, 1995, and (ii) any
additional capital expenditures incurred for the purpose of complying with legal
or regulatory requirements, or for complying with contractual requirements in
existence on May 1, 1993, or for replacing or maintaining the productive
capacity of the Company's oil and gas properties and facilities, during such
period.
 
     "Permitted Investments" means (a) direct obligations of, and obligations
fully guaranteed by, the United States of America or any agency or
instrumentality of the United States of America, (b) demand and time deposits
with, and certificates of deposit and bankers' acceptances issued by, any bank
or trust company organized under the laws of the United States of America or any
State thereof whose unsecured, unguaranteed long-term debt obligations are rated
not less than "A" (or the then equivalent rating) by the rating service of
Standard & Poor's Corporation or of Moody's Investors Service, Inc., or whose
unsecured, unguaranteed commercial paper obligations are rated not less than
"A-2" (or the then equivalent rating) by the rating service of Standard & Poor's
Corporation or not less than "P-2" (or the then equivalent rating) by the rating
service of Moody's Investors Service, Inc., or upon the discontinuance of both
of such services, such other nationally recognized rating service or services,
as the case may be, as shall be selected by the Obligors with the consent of the
Trustee, (c) repurchase agreements pursuant to a written agreement with respect
to any obligation described in clauses (a) and (b) above (provided that such
agreements are entered into on terms and conditions substantially similar to the
terms and conditions set forth in the form of Master Repurchase Agreement
promulgated by the Public Securities Association with a "Buyer's Margin Amount",
as defined therein, as least equal to 95%) entered into with entities whose
unsecured, unguaranteed long-term debt
 
                                       70
<PAGE>   73
 
obligations are rated not less than "A" (or the then equivalent rating) by the
rating service of Standard & Poor's Corporation or of Moody's Investors Service,
Inc., or whose unsecured, unguaranteed commercial paper obligations are rated
not less than "A" (or the then equivalent rating) by the rating service of
Standard & Poor's Corporation or of Moody's Investors Service, Inc., (d)
commercial paper (including both noninterest-bearing discount obligations and
interest-bearing obligations payable on demand or on a specified date not later
than 270 days from the date of acquisition thereof and having a rating of not
less than "A-2" (or the then equivalent rating) by the rating service of
Standard & Poor's Corporation or not less than "P-2" (or the then equivalent
rating) by the rating service of Moody's Investors Service, Inc., or upon the
discontinuance of both of such services, such other nationally recognized rating
service or services, as the case may be, as shall be selected by the Obligors
with the consent of the Trustee, (e) participations (purchased from any bank
whose unsecured, unguaranteed long-term debt obligations are rated not less than
"A" (or the then equivalent rating) by the rating service of Standard & Poor's
Corporation or of Moody's Investors Service, Inc., without recourse to the
selling bank as a part of an established investment program of such bank
pursuant to which it regularly sells participations to other persons for short
term investment) in unsecured debt (not to include debt of any person in excess
of $10,000,000) of its major corporate customers (whose debt instruments are,
without support from the joint or guaranty liability of any other person, rated
"investment grade") of such bank, bearing interest at or below the prime rate or
similar rate of such bank and having a maturity not later than ninety (90) days
from the date of purchase thereof, (f) cash maintained in brokerage accounts,
and (g) direct obligations of any money market fund or other similar investment
company all of whose investments consist of obligations described in the
foregoing clauses of this definition and that is rated "Am" or higher by the
rating service of Standard & Poor's Corporation or of Moody's Investors Service,
Inc.
 
     "Permitted Purchase Money Debt" means Debt incurred solely for the purpose
of financing the acquisition of tangible personal Property acquired for use in
the ordinary course of business in an aggregate principal amount at any time
outstanding not to exceed $3,000,000.
 
     "Physical Asset Sale" means a sale (other than an Oil and Gas Property Sale
or a Forward Sale) of any Property for aggregate consideration exceeding
$5,000,000.
 
     "Qualified Interest Expense" for any period shall mean Interest Expense
paid during the period on outstanding Senior Debt of the Obligors or on any
Refinancing Debt of the Obligors to the extent the net proceeds from the
issuance or sale of such Refinancing Debt were used to redeem or retire Secured
Notes.
 
     "Qualified Subsidiary" means a subsidiary that is not a Non-Qualified
Subsidiary.
 
     "Quarterly Base EBITDA" means, with respect to any calendar quarter, the
sum of (a) West Panhandle Quarterly Base EBITDA with respect to such calendar
quarter, (b) Non West Panhandle Quarterly Base EBITDA with respect to such
calendar quarter and (c) Helium Quarterly Base EBITDA with respect to such
calendar quarter.
 
     "Release Price" with respect to a Collateral Sale, means, as of any date of
determination, (a) if the Collateral sold is West Panhandle Collateral, an
amount equal to 120% of the product of (i) the West Panhandle Collateral Sale
Percentage, (ii) 60% and (iii) the Secured Debt Amount at such date less the
amount of cash or other assets on deposit in the Collateral Account at such
date; and (b) if the Collateral sold is HCLP Collateral, an amount equal to 120%
of the product of (i) the percentage interest in HCLP Collateral sold, (ii) 40%
and (iii) the Secured Debt Amount at such date less the amount of cash or other
assets on deposit in the Collateral Account at such date.
 
     "Requisite Majority" means, with respect to any vote, action, direction,
consent or waiver by holders of Secured Notes, the holders of at least
two-thirds in aggregate face amount at stated maturity of the outstanding
Secured Notes for which responses to a solicitation of such vote, action,
consent or waiver have been received; provided, however, that a "Requisite
Majority" shall in no event be less than the holders of a majority in aggregate
face amount at stated maturity of all Secured Notes then outstanding.
 
     "Reserve Report" means a report prepared with respect to Hydrocarbon
reserves in accordance with guidelines published by the SEC and, to the maximum
extent possible consistent with such guidelines, in substantially the form of
the D&M Report.
 
                                       71
<PAGE>   74
 
     "Secured Debt Amount" means, as of any date of determination, the sum of
(i) the aggregate Accreted Value of the Secured Notes on such date, if such date
is on or prior to June 30, 1995, or 100% of the principal amount of the Secured
Notes plus accrued but unpaid interest thereon to such date, if such date is
after June 30, 1995 and (ii) the principal amount of First Lien Debt outstanding
on such date.
 
     "Senior Debt Default" when used with respect to an Obligor means any
default in the payment of the principal of or sinking fund installments, if any,
due with respect to, fees in respect of or interest on, any First Lien Debt of
such Obligor or any default, or any event which, with notice or lapse of time or
both, would constitute a default, in any other agreement, term or condition
contained in any agreement under which any First Lien Debt of such Obligor is
issued or secured.
 
     "Senior Debt Retirement" for a period shall mean (i) $60,000,000 for the
one-year period ending June 30, 1994 and (ii) $110,000,000 for the two-year
period ending June 30, 1995.
 
     "Stated Price" means, with respect to any Secured Note as of any date of
determination, (i) the Accreted Value thereof on the date of determination, if
such date is on or prior to June 30, 1995 or (ii) 100% of the face amount (at
maturity) thereof plus accrued but unpaid interest thereon to the date of
determination, if such date is after June 30, 1995, and, in the cases, and only
in the cases, of an optional redemption of Secured Notes effected pursuant to
the terms of the Secured Notes, or of an offer to purchase any Secured Note made
pursuant to the Change in Control provisions of the Secured Indenture, the
premium (if any) payable pursuant to such terms of the Secured Notes or such
Change in Control provisions, as applicable.
 
     "Subordinated Debt" means Debt that, by its terms, is junior in right of
payment to the Secured Notes.
 
     "West Panhandle Collateral Sale Percentage" means, (a) with respect to a
Collateral Sale of all the West Panhandle Collateral, 100% and (b) with respect
to a Collateral Sale of a portion of the West Panhandle Collateral, the quotient
(stated as a percentage) of (a) the Sale Percentage Numerator and (b) the Sale
Percentage Denominator. For purposes of this definition, (a) "Sale Percentage
Numerator" means (i) if such Collateral Sale is a Fractional Sale of the West
Panhandle Collateral, the undivided percentage interest in the West Panhandle
Collateral sold pursuant to such Collateral Sale, or (ii) if such Collateral
Sale is an Oil and Gas Property Sale, the volume of proved reserves of natural
gas equivalents attributable to the portion of the West Panhandle Collateral
sold pursuant to such Collateral Sale, as specified in the D&M Report, or (iii)
if such Collateral Sale is a Forward Sale, the volume of natural gas equivalents
deliverable pursuant to such Collateral Sale on and after the first anniversary
of such date, or (iv) if the Collateral Sale is a Physical Asset Sale, the net
book value, as of the date of the most recent balance sheet of the Company prior
to the date of determination, of the assets sold pursuant to such Collateral
Sale; and (b) "Sale Percentage Denominator" means (i) if such Collateral Sale is
a Fractional Sale of the West Panhandle Collateral, 1, or (ii) if such
Collateral Sale is an Oil and Gas Property Sale, 581,790,000 Mcfe, or (iii) if
such Collateral Sale is a Forward Sale, the total volume of proved reserves of
natural gas equivalents attributable to the West Panhandle Collateral in the
most recent Reserve Report that includes all reserves constituting West
Panhandle Collateral, or (iv) if such Collateral Sale is a Physical Asset Sale,
the net book value, as of the date of the most recent balance sheet of the
Company prior to the date of determination, of all the West Panhandle
Collateral.
 
     "West Panhandle EBITDA Reduction Percentage" means, with respect to a
reduction of West Panhandle Quarterly Base EBITDA amounts resulting from a
Collateral Sale of a portion of West Panhandle Collateral, the quotient (stated
as a percentage) of (a) the Sale Percentage Numerator and (b) the Sale
Percentage Denominator. For purposes of this definition, (a) "Sale Percentage
Numerator" means (i) if such Collateral Sale is a Fractional Sale of the West
Panhandle Collateral, the undivided percentage interest in the West Panhandle
Collateral sold pursuant to such Collateral Sale, or (ii) if such Collateral
Sale is an Oil and Gas Property Sale, the volume of proved reserves of natural
gas equivalents attributable to the portion of the West Panhandle Collateral
sold pursuant to such Collateral Sale, as specified in the D&M Report, or (iii)
if such Collateral Sale is a Forward Sale, the volume of natural gas equivalents
deliverable pursuant to such Collateral Sale on and after the first anniversary
of the date of such Forward Sale, or (iv) if the Collateral Sale is a Physical
Asset Sale, the net book value, as of the date of the most recent balance sheet
of the Company prior to the date of determination, of the assets sold pursuant
to such Collateral Sale; and (b) "Sale Percentage Denominator" means (i) if such
Collateral Sale is a Fractional Sale of the West Panhandle
 
                                       72
<PAGE>   75
 
Collateral, 1, or (ii) if such Collateral Sale is an Oil and Gas Property Sale,
581,790,000 Mcfe, or (iii) if such Collateral Sale is a Forward Sale, the total
volume of proved reserves of natural gas equivalents attributable to the West
Panhandle Collateral in the most recent Reserve Report that includes all
reserves constituting West Panhandle Collateral, or (iv) if such Collateral Sale
is a Physical Asset Sale, the net book value, as of the date of the most recent
balance sheet of the Company prior to the date of determination, of all the West
Panhandle Collateral.
 
     "West Panhandle Quarterly Base EBITDA" means, with respect to any calendar
quarter set forth below, the amount, in dollars, set forth below opposite such
calendar quarter; provided, that upon each sale by MOC of a portion of the West
Panhandle Collateral after June 30, 1993, West Panhandle Quarterly Base EBITDA
with respect to any calendar quarter beginning after the date of such sale,
shall be an amount equal to the product of (a) the West Panhandle Quarterly Base
EBITDA amount in effect immediately prior to such sale with respect to such
calendar quarter and (b) the excess of (i) 100% over (ii) the West Panhandle
EBITDA Reduction Percentage with respect to such sale.
 
<TABLE>
<CAPTION>
                                                                      WEST PANHANDLE
                                                                   QUARTERLY BASE EBITDA
                                                                   ---------------------
        <S>                                                        <C>
        September 30, 1993.......................................         6,739,000
        December 31, 1993........................................        14,577,000
        March 31, 1994...........................................        11,562,000
        June 30, 1994............................................         1,266,000
        September 30, 1994.......................................         8,540,000
        December 31, 1994........................................        14,972,000
        March 31, 1995...........................................        12,210,000
        June 30, 1995............................................         1,337,000
</TABLE>
 
                  CERTAIN U.S. FEDERAL INCOME TAX CONSEQUENCES
 
SCOPE AND LIMITATIONS
 
     This section discusses the material federal income tax consequences under
current law of the ownership and disposition of Secured Notes that are acquired
in the Offering. It does not, however, discuss every aspect of federal income
taxation that may be relevant to a particular taxpayer under special
circumstances or to foreign corporations or persons who are not citizens of the
United States or who are otherwise subject to special tax treatment under the
federal income tax laws, and it does not discuss the effect of any applicable
foreign, state, or local tax laws.
 
     Except as otherwise indicated, statements of legal conclusion regarding tax
treatments, tax effects or tax consequences that are set forth in this section
reflect the opinion of Baker & Botts, L.L.P., counsel for the Obligors. The
conclusions are based primarily upon the Internal Revenue Code of 1986, as
amended (the "Code"), the existing regulations thereunder, and the current
rulings and decisions interpreting such provisions, all of which are subject to
change, possibly with retroactive effect. Such conclusions also take into
account the proposed treasury regulations under Sections 1271-1275 of the Code.
Proposed regulations, however, are not legally binding and may be modified
before becoming final or may be withdrawn without ever becoming final.
 
     No ruling has been requested from the Internal Revenue Service ("IRS") on
any aspect of the Offerings, and the IRS may disagree with some conclusions set
forth below.
 
     ACCORDINGLY, NOTEHOLDERS ARE URGED TO CONSULT THEIR OWN TAX ADVISORS.
 
STATED INTEREST
 
     The receipt of stated interest on the Secured Notes will not be taxable to
Noteholders but, rather, such stated interest will be included in the original
issue discount ("OID") reportable under the rules described below.
 
                                       73
<PAGE>   76
 
ORIGINAL ISSUE DISCOUNT
 
     The Secured Notes will be issued with OID within the meaning of Section
1273(a) of the Code. The amount of OID on the Secured Notes will equal the
excess of their "Redemption Price" over their "Issue Price." The "Redemption
Price" will equal the sum of the face amount and the aggregate amount of stated
interest payments to be made over the life of the Secured Notes. The "Issue
Price" of the Secured Notes will be the first price at which a substantial
portion of the Secured Notes are sold to the public in the Offering. All Secured
Notes acquired by a particular Noteholder in the Offering will be treated as a
single debt instrument for purposes of applying the OID rules.
 
     The OID described in the preceding paragraph will accrue daily on the
Secured Notes on a constant yield basis over their term. Each Noteholder
generally must include in income for each taxable year the daily portion of OID
that accrues during such year while he holds the Notes (including the purchase
date and excluding the disposition date). The daily portion is determined by
allocating to each day of an accrual period (generally, each six-month period
or, in the case of the initial period, the shorter period from the issue date) a
pro rata portion of an amount determined by multiplying (i) the "adjusted issue
price" of the Secured Notes at the beginning of the accrual period by (ii) 50%
of their yield to maturity (determined on the basis of semi-annual compounding
and without reference to actual interest payments). The "adjusted issue price"
of the Secured Notes at the beginning of an accrual period will equal their
Issue Price, increased by the aggregate amount of OID that has accrued on the
Secured Notes in all prior accrual periods, and decreased by all payments
(including stated interest payments) made during all prior accrual periods.
 
     A Noteholder's tax basis in the Secured Notes will be increased by the OID
includible in his taxable income under the foregoing rules and will be reduced
by any amounts (including stated interest) received by him with respect to the
Notes.
 
     The Company will report to each Noteholder and to the IRS for each calendar
year the amount of OID attributable to the Secured Notes while held by such
Noteholder for such year.
 
MARKET DISCOUNT
 
     The market discount rules may affect resale of the Secured Notes. If a
person purchases a Secured Note at a market discount and thereafter recognizes
gain upon its disposition, such gain will be taxable as ordinary interest income
to the extent of the market discount that accrued during the period the
purchaser held such Note. Generally, market discount will exist on the purchase
of a Secured Note if the purchase price is less than the sum of the Issue Price
of the Note and the OID accrued thereon prior to such purchase. Thus, market
discount will not exist on Secured Notes that are purchased in the Offering,
except for those Notes (if any) that are purchased for less than the Issue
Price. Market discount income is recognized on a gift of a Note, as well as upon
its sale.
 
DISPOSITION OF SECURED NOTES
 
     A Noteholder will recognize gain or loss upon a sale, redemption, or other
taxable disposition of a Secured Note measured by the difference between (i) the
amount of cash and the fair market value of property received and (ii) his tax
basis in the Note. Subject to the market discount rules discussed above, such
gain or loss will be capital gain or loss if the property disposed of is a
capital asset in the hands of the Noteholder.
 
BACKUP WITHHOLDING
 
     Under the backup withholding rules, interest otherwise payable to a holder
of Secured Notes and the proceeds from any disposition of Secured Notes may be
subject to backup withholding at a rate of 31% unless the Noteholder (i) is a
corporation or comes within certain other exempt categories and, demonstrates
that fact when required, or (ii) provides a correct taxpayer identification
number, certifies as to no loss of exemption from backup withholding, and
otherwise complies with applicable requirements of the backup withholding rules.
 
                                       74
<PAGE>   77
 
                              PLAN OF DISTRIBUTION
 
     Offers to purchase Secured Notes are being considered by the Obligors on a
continuing basis. The Obligors may sell Secured Notes directly or through
underwriters or agents acting on a best efforts basis or as otherwise indicated
in a Prospectus Supplement. Any such underwriter or agent involved in the offer
and sale of the Secured Notes will be named in an applicable Prospectus
Supplement.
 
     The proceeds of the sale of the Secured Notes offered hereby will be used
to fund all or a portion of the Company's $42.75 million share of the settlement
payment to be made to Unocal. The settlement of the lawsuit with Unocal is
subject to court approval, and this Offering will not be consummated unless and
until such court approval is obtained. A hearing before the court is currently
scheduled for March   , 1994 to determine the fairness, reasonableness and
adequacy of the settlement and whether it should be approved by the court. See
"Unocal Litigation and Settlement."
 
     The consummation of this Offering is also conditioned upon the sale of an
aggregate amount of Secured Notes that would result in proceeds of at least $40
million, before deducting expenses of the Company estimated at $          ,
unless a Prospectus Supplement hereto otherwise provides. The Secured Notes may
be offered and sold at a fixed price or prices, which may be changed, or from
time to time at market prices prevailing at the time of sale, at prices related
to such prevailing market prices or at negotiated prices. Based on discussions
with dealers, the Obligors believe that, as of January 12, 1994, offered prices
by such dealers for Secured Notes were higher than the Accreted Value of the
Secured Notes as of that date.
 
     The Obligors also may, from time to time, authorize underwriters acting as
agents of the Obligors to offer and sell the Secured Notes upon the terms and
conditions set forth in any Prospectus Supplement. In connection with the sale
of Secured Notes, underwriters may be deemed to have received compensation from
the Obligors in the form of underwriting discounts or commissions and may also
receive commissions from purchasers of Secured Notes for whom they may act as
agent. Underwriters may sell Secured Notes to or through dealers, and such
dealers may receive compensation in the form of discounts, concessions or
commissions from the underwriters and/or commissions (which may be changed from
time to time) from the purchasers for whom they may act as agent.
 
     If the Obligors, directly or through agents, solicit offers to purchase
Secured Notes, the Obligors reserve the sole right to accept and, together with
their agents, to reject, in whole or in part, any proposed purchase of Secured
Notes.
 
     Any underwriting compensation paid by the Obligors to underwriters or
agents in connection with the offering of Secured Notes, and any discounts,
concessions or commissions allowed by underwriters to participating dealers,
will be set forth in an applicable Prospectus Supplement. Underwriters, dealers
and agents participating in the distribution of the Secured Notes may be deemed
to be underwriters under the Securities Act, and any discounts and commissions
received by them and any profit realized by them on resale of the Secured Notes
may be deemed to be underwriting discounts and commissions under the Securities
Act. Underwriters, dealers and agents may be entitled, under agreements with the
Obligors, to indemnification against and contribution toward certain civil
liabilities, including liabilities under the Securities Act, and to
reimbursement by the Obligors for certain expenses. Unless otherwise indicated
in a Prospectus Supplement, any such agent will be acting on a best efforts
basis for the period of its appointment.
 
     Delayed Delivery Arrangements. If so indicated in an applicable Prospectus
Supplement, the Obligors will authorize underwriters or other persons acting as
the Obligors' agents to solicit offers by certain institutions to purchase
Secured Notes from the Obligors at the public offering price set forth in such
Prospectus Supplement pursuant to Delayed Delivery Contracts ("Contracts")
providing for payment and delivery on the date or dates stated in such
Prospectus Supplement. Each Contract will be for an amount not less than, and
the aggregate principal amount of Secured Notes sold pursuant to Contracts shall
not be less nor more than, the respective amounts stated in such Prospectus
Supplement. Institutions with whom Contracts, when authorized, may be made
include commercial and savings banks, insurance companies, pension funds,
investment companies, education and charitable institutions and other
institutions, but will in all cases be subject to the approval of the Obligors.
Unless otherwise stated in a Prospectus Supplement, contracts will not be
subject to any conditions except (i) the purchase by an institution of the
Secured Notes covered by its Contracts shall not at the time of delivery be
prohibited under the laws of any jurisdiction in the United States
 
                                       75
<PAGE>   78
 
to which such institution is subject, (ii) approval of the Settlement Agreement
shall have been granted by the Court having jurisdiction over the Unocal
litigation, (iii) an amount of Secured Notes that would result in proceeds of at
least $40 million, before deducting expenses of the Company estimated at
$       , are sold, and (iv) if the Secured Notes are being sold to
underwriters, the Obligors shall have sold to such underwriters the total
principal amount of the Secured Notes less the principal amount thereof covered
by Contracts. Agents and underwriters will have no responsibility in respect of
the delivery or performance of Contracts.
 
                                 LEGAL OPINIONS
 
     The validity of the issuance of the Secured Notes offered by this
Prospectus will be passed upon for the Company by Baker & Botts, L.L.P., Dallas,
Texas. Robert L. Stillwell, a partner of Baker & Botts, L.L.P., is a director of
the Company.
 
                                    EXPERTS
 
     The Consolidated Financial Statements of the Company included in this
Prospectus and the financial statement schedules of the Company included
elsewhere in the Registration Statement of which this Prospectus is a part, to
the extent and for the periods indicated in their reports, have been audited by
Arthur Andersen & Co., independent public accountants, as indicated in their
reports with respect thereto, and are included herein in reliance upon the
authority of said firm as experts in giving said reports. Reference is made to
the report on the Consolidated Financial Statements, which includes an
explanatory paragraph that describes the litigation discussed in Notes 2, 9 and
14 of those Consolidated Financial Statements.
 
     The evaluation of DeGolyer and MacNaughton, independent consulting
petroleum engineers, of certain of Mesa's proved reserves of oil and natural gas
and related information set forth herein and based on such evaluation are
included herein in reliance upon the authority of such firm as an expert with
respect to such matters.
 
                                       76
<PAGE>   79
 
                   INDEX TO CONSOLIDATED FINANCIAL STATEMENTS
 
<TABLE>
<CAPTION>
                                                                                        PAGE
                                                                                        ----
<S>                                                                                     <C>
MESA Inc. Consolidated Financial Statements for the
  Nine Months Ended September 30, 1993 and 1992 (Unaudited)
  Consolidated Statements of Operations...............................................  F-2
  Consolidated Balance Sheets.........................................................  F-3
  Consolidated Statements of Cash Flows...............................................  F-4
  Consolidated Statement of Changes in Stockholders' Equity...........................  F-5
  Notes to Consolidated Financial Statements..........................................  F-6
MESA Inc. Consolidated Financial Statements for the
  Years Ended December 31, 1992, 1991 and 1990
  Report of Independent Public Accountants............................................  F-21
  Consolidated Statements of Operations...............................................  F-22
  Consolidated Balance Sheets.........................................................  F-23
  Consolidated Statements of Cash Flows...............................................  F-24
  Consolidated Statement of Changes in Stockholders' Equity...........................  F-25
  Notes to Consolidated Financial Statements..........................................  F-26
  Supplemental Financial Data.........................................................  F-43
</TABLE>
 
                                       F-1
<PAGE>   80
 
                                   MESA INC.
 
                     CONSOLIDATED STATEMENTS OF OPERATIONS
                     (IN THOUSANDS, EXCEPT PER SHARE DATA)
                                  (UNAUDITED)
 
<TABLE>
<CAPTION>
                                                                          NINE MONTHS ENDED
                                                                            SEPTEMBER 30
                                                                       -----------------------
                                                                         1993          1992
                                                                       ---------     ---------
<S>                                                                    <C>           <C>
REVENUES:
  Natural gas........................................................  $ 101,340     $ 102,631
  Natural gas liquids................................................     43,781        40,894
  Oil and condensate.................................................      8,743        14,279
  Other..............................................................      3,165           842
                                                                       ---------     ---------
                                                                         157,029       158,646
                                                                       ---------     ---------
COSTS AND EXPENSES:
  Lease operating....................................................     38,582        31,490
  Production and other taxes.........................................     15,012        12,634
  Exploration charges................................................      2,178         9,099
  General and administrative.........................................     16,514        18,954
  Depreciation, depletion and amortization...........................     70,317        79,603
                                                                       ---------     ---------
                                                                         142,603       151,780
                                                                       ---------     ---------
OPERATING INCOME.....................................................     14,426         6,866
                                                                       ---------     ---------
OTHER INCOME (EXPENSE):
  Interest income....................................................      8,156        10,891
  Interest expense...................................................   (105,000)     (108,129)
  Gains on dispositions of oil and gas properties....................      9,600        12,250
  Securities gains...................................................      5,778        10,525
  Other..............................................................      8,027        (4,126)
                                                                       ---------     ---------
                                                                         (73,439)      (78,589)
                                                                       ---------     ---------
NET LOSS.............................................................  $ (59,013)    $ (71,723)
                                                                       ---------     ---------
                                                                       ---------     ---------
NET LOSS PER COMMON SHARE............................................  $   (1.53)    $   (1.86)
                                                                       ---------     ---------
                                                                       ---------     ---------
AVERAGE COMMON SHARES OUTSTANDING....................................     38,615        38,571
                                                                       ---------     ---------
                                                                       ---------     ---------
</TABLE>
 
         (See accompanying notes to consolidated financial statements.)
 
                                       F-2
<PAGE>   81
 
                                   MESA INC.
 
                          CONSOLIDATED BALANCE SHEETS
                     (IN THOUSANDS, EXCEPT PER SHARE DATA)
 
                                     ASSETS
 
<TABLE>
<CAPTION>
                                                                     SEPTEMBER 30,     DECEMBER 31,
                                                                         1993              1992
                                                                     -------------     ------------
                                                                      (UNAUDITED)
<S>                                                                  <C>               <C>
CURRENT ASSETS:
  Cash and cash investments........................................    $ 104,840        $  157,197
  Marketable securities............................................       17,330            11,918
  Accounts receivable..............................................       35,473            44,637
  Notes receivable.................................................       37,428                --
  Other............................................................        4,389             5,498
                                                                     -------------     ------------
          Total current assets.....................................      199,460           219,250
                                                                     -------------     ------------
PROPERTY, PLANT AND EQUIPMENT:
  Oil and gas properties, wells and equipment, using the successful
     efforts method of accounting..................................    1,842,145         1,851,555
  Office and other.................................................       40,750            40,601
  Accumulated depreciation, depletion and amortization.............     (665,848)         (611,905)
                                                                     -------------     ------------
                                                                       1,217,047         1,280,251
                                                                     -------------     ------------
OTHER ASSETS:
  Restricted cash of subsidiary partnership........................       62,543            64,339
  Notes receivable.................................................           --            30,315
  Gas balancing receivable.........................................       44,429            42,089
  Other............................................................       36,623            40,279
                                                                     -------------     ------------
                                                                         143,595           177,022
                                                                     -------------     ------------
                                                                       $1,560,102       $1,676,523
                                                                     -------------     ------------
                                                                     -------------     ------------
                               LIABILITIES AND STOCKHOLDERS' EQUITY
CURRENT LIABILITIES:
  Current maturities on long-term debt.............................    $  86,371        $   44,555
  Accounts payable and accrued liabilities.........................       34,360            39,397
  Interest payable.................................................        5,507            32,445
                                                                     -------------     ------------
          Total current liabilities................................      126,238           116,397
                                                                     -------------     ------------
LONG-TERM DEBT.....................................................    1,182,613         1,241,600
                                                                     -------------     ------------
DEFERRED REVENUE...................................................       23,104            25,982
                                                                     -------------     ------------
OTHER LIABILITIES..................................................       95,682           100,231
                                                                     -------------     ------------
CONTINGENCIES
MINORITY INTEREST..................................................        5,412             7,961
                                                                     -------------     ------------
STOCKHOLDERS' EQUITY:
  Preferred stock, $.01 par value, authorized 10,000,000 shares; no
     shares issued and outstanding.................................           --                --
  Common stock, $.01 par value, authorized 100,000,000 shares;
     outstanding 39,010,467 and 38,570,544 shares, respectively....          390               386
  Additional paid-in capital.......................................      274,908           273,198
  Accumulated deficit..............................................     (148,245)          (89,232)
                                                                     -------------     ------------
                                                                         127,053           184,352
                                                                     -------------     ------------
                                                                       $1,560,102       $1,676,523
                                                                     -------------     ------------
                                                                     -------------     ------------
</TABLE>
 
         (See accompanying notes to consolidated financial statements.)
 
                                       F-3
<PAGE>   82
 
                                   MESA INC.
 
                     CONSOLIDATED STATEMENTS OF CASH FLOWS
                                 (IN THOUSANDS)
                                  (UNAUDITED)
 
<TABLE>
<CAPTION>
                                                                           NINE MONTHS ENDED
                                                                             SEPTEMBER 30
                                                                         ---------------------
                                                                           1993         1992
                                                                         --------     --------
<S>                                                                      <C>          <C>
CASH FLOWS FROM OPERATING ACTIVITIES:
  Net loss.............................................................  $(59,013)    $(71,723)
  Adjustments to reconcile net loss to net cash from operating
     activities:
     Depreciation, depletion and amortization..........................    70,317       79,603
     Gains on dispositions of oil and gas properties...................    (9,600)     (12,250)
     Accreted interest on discount notes...............................    30,536           --
     Accrued interest exchanged for discount notes.....................    15,395           --
     Natural gas hedging activities....................................       324       (8,971)
     Securities gains..................................................    (5,778)     (10,525)
     Changes in operating receivables and payables.....................   (36,578)     (20,837)
     Other.............................................................     6,325       11,207
                                                                         --------     --------
     Cash provided by (used in) operating activities...................    11,928      (33,496)
                                                                         --------     --------
CASH FLOWS FROM INVESTING ACTIVITIES:
  Capital expenditures.................................................   (22,440)     (56,849)
  Changes in marketable securities, net................................       384       (4,746)
  Proceeds from dispositions of oil and gas properties.................    26,118       11,429
  Collection of notes receivable.......................................     5,943       21,078
  Other................................................................    (6,015)      (6,455)
                                                                         --------     --------
     Cash provided by (used in) investing activities...................     3,990      (35,543)
                                                                         --------     --------
CASH FLOWS FROM FINANCING ACTIVITIES:
  Repayments of long-term debt.........................................   (61,388)     (24,550)
  Debt issue costs and other...........................................    (6,887)      (3,651)
                                                                         --------     --------
     Cash used in financing activities.................................   (68,275)     (28,201)
                                                                         --------     --------
NET DECREASE IN CASH AND CASH INVESTMENTS..............................   (52,357)     (97,240)
CASH AND CASH INVESTMENTS AT BEGINNING OF PERIOD.......................   157,197      232,155
                                                                         --------     --------
CASH AND CASH INVESTMENTS AT END OF PERIOD.............................  $104,840     $134,915
                                                                         --------     --------
                                                                         --------     --------
</TABLE>
 
         (See accompanying notes to consolidated financial statements.)
 
                                       F-4
<PAGE>   83
 
                                   MESA INC.
 
           CONSOLIDATED STATEMENT OF CHANGES IN STOCKHOLDERS' EQUITY
                                 (IN THOUSANDS)
                                  (UNAUDITED)
 
<TABLE>
<CAPTION>
                                                           COMMON STOCK     ADDITIONAL
                                                          ---------------    PAID-IN     ACCUMULATED
                                                          SHARES   AMOUNT    CAPITAL       DEFICIT
                                                          ------   ------   ----------   -----------
<S>                                                       <C>      <C>      <C>          <C>
Balance, December 31, 1992..............................  38,571    $386     $ 273,198    $ (89,232)
  Net loss..............................................      --      --            --      (59,013)
  Common Stock issued for 0% Convertible Notes..........     439       4         1,710           --
                                                          ------   ------   ----------   -----------
Balance, September 30, 1993.............................  39,010    $390     $ 274,908    $(148,245)
                                                          ------   ------   ----------   -----------
                                                          ------   ------   ----------   -----------
</TABLE>
 
         (See accompanying notes to consolidated financial statements.)
 
                                       F-5
<PAGE>   84
 
                                   MESA INC.
 
                   NOTES TO CONSOLIDATED FINANCIAL STATEMENTS
                               SEPTEMBER 30, 1993
                                  (UNAUDITED)
 
(1) ORGANIZATION AND SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES
 
     MESA Inc., a Texas corporation, was formed in connection with a transaction
(the Corporate Conversion) which reorganized the business of Mesa Limited
Partnership (the Partnership). The Partnership was formed in 1985 to succeed to
the business of Mesa Petroleum Co. (Original Mesa). Unless the context otherwise
requires, as used herein the term "Company" refers to MESA Inc. and its
subsidiaries taken as a whole and includes its predecessors.
 
     The consolidated financial statements of the Company for the nine-month
periods ended September 30, 1993 and 1992 are unaudited but reflect, in the
opinion of management, all adjustments (which include only normal recurring
adjustments) necessary to fairly present the results for such periods. The
accompanying financial statements should be read in conjunction with the audited
consolidated financial statements and notes thereto contained in the Annual
Report of the Company for the year ended December 31, 1992.
 
PRINCIPLES OF CONSOLIDATION
 
     The Company owns and operates its oil and gas properties and other assets
through various direct and indirect subsidiary partnerships. At the beginning of
1993, the Company owned a 95.86% limited partnership interest and the general
partner (the General Partner) owned a 4.14% general partner interest in the
direct subsidiary partnerships. The debt exchange described in Notes 2, 4 and 6
included issuance of approximately $29.3 million of 0% convertible notes which
were convertible into approximately 7.5 million shares of common stock. As of
September 30, 1993, $1.7 million of 0% convertible notes had been converted into
439,923 shares of common stock. As a result, the Company's limited partnership
interest in the direct subsidiary partnerships has increased to 95.90% and the
General Partner's interest has decreased to 4.10%. Conversion of the remaining
0% convertible notes to common stock in the fourth quarter of 1993 will further
increase the Company's limited partnership interest to 96.51% and further
decrease the General Partner's interest to 3.49%. The accompanying consolidated
financial statements reflect the consolidated accounts of the Company and the
subsidiary partnerships after elimination of intercompany transactions. The
General Partner's interest is reflected as a minority interest. See Note 10 for
a discussion of recent events affecting the General Partner's interest and the
Company's subsidiary partnerships.
 
     Certain reclassifications have been made to amounts reported in previous
years to conform to 1993 presentation.
 
STATEMENTS OF CASH FLOWS
 
     For purposes of the statements of cash flows, the Company classifies all
cash investments with original maturities of three months or less as cash and
cash investments.
 
INVESTMENTS
 
     Investments in marketable securities are stated at the lower of cost or
market value and are classified as current or noncurrent, depending on
management's intent at the balance sheet date. Periodic changes in the stated
value of the marketable securities portfolios are reflected in income in the
case of current investments and in stockholders' equity in the case of
noncurrent investments. The cost of securities sold is determined on the
first-in, first-out basis. The Company also enters into various futures
contracts which are not accounted for as hedges of existing assets and are
periodically adjusted to market prices. Gains and losses from such contracts are
included in securities gains in the statement of operations.
 
     In May 1993, the Financial Accounting Standards Board issued Statement of
Financial Accounting Standards (SFAS) No. 115, "Accounting for Certain
Investments in Debt and Equity Securities," which is
 
                                       F-6
<PAGE>   85
 
                                   MESA INC.
 
           NOTES TO CONSOLIDATED FINANCIAL STATEMENTS -- (CONTINUED)
 
required to be adopted in 1994. SFAS No. 115 addresses the accounting and
reporting for investments in equity securities that have readily determinable
fair values and for all investments in debt securities. The Company's current
portfolio of securities would be classified as trading securities under the
provisions of SFAS No. 115 and would be reported at fair value, with unrealized
gains and losses included in earnings. Purchases, sales and the related gains
and losses associated with the Company's securities transactions are currently
reported as cash flows from investing activities in the cash flow statement.
Under the provisions of SFAS No. 115, transactions in trading securities will be
classified as cash flows from operating activities. The Company does not expect
the adoption of SFAS No. 115 to have a material effect on its financial position
or results of operations.
 
OIL AND GAS PROPERTIES
 
     Under the successful efforts method of accounting, all costs of acquiring
unproved oil and gas properties and drilling and equipping exploratory wells are
capitalized pending determination of whether the properties have proved
reserves. If an exploratory well is determined to be nonproductive, the drilling
and equipment costs of the well are expensed at that time. All development
drilling and equipment costs are capitalized. Capitalized costs of proved
properties and estimated future dismantlement and abandonment costs are
amortized on a property-by-property basis using the unit-of-production method.
Geological and geophysical costs and delay rentals are expensed as incurred.
 
     Unproved properties are periodically assessed for impairment of value and a
loss is recognized at the time of impairment. The aggregate carrying value of
proved properties is periodically compared with the undiscounted future net cash
flows from proved reserves, determined in accordance with Securities and
Exchange Commission (SEC) regulations, and a loss is recognized if permanent
impairment of value is determined to exist. A loss is recognized on proved
properties expected to be sold in the event that carrying value exceeds expected
sales proceeds.
 
NET LOSS PER COMMON SHARE
 
     The computations of net loss per common share are based on the weighted
average number of common shares outstanding during each period.
 
FAIR VALUE OF FINANCIAL INSTRUMENTS
 
     The Company's financial instruments consist of cash, marketable securities,
short-term trade receivables and payables, notes receivable, restricted cash and
long-term debt. The carrying values of cash, marketable securities, short-term
trade receivables and payables, notes receivable and restricted cash approximate
fair value. The fair value of long-term debt is estimated based on the market
prices for the Company's publicly traded debt and on current rates available for
similar debt with similar maturities and security for the Company's remaining
debt.
 
GAS REVENUES
 
     The Company recognizes its ownership interest in natural gas sales as
revenue. Actual production quantities sold by the Company may be different than
its ownership share of production in a given period. If the Company's sales
exceed its ownership share of production, the differences are recorded as
deferred revenue. Gas balancing receivables are recorded when the Company's
ownership share of production exceeds sales. The Company also accrues production
expenses related to its ownership share of production. At September 30, 1993,
the Company had produced and sold a net 11.9 billion cubic feet (Bcf) of natural
gas less than its ownership share of production and had recorded gas balancing
receivables, net of deferred revenues, of approximately $24.4 million.
 
                                       F-7
<PAGE>   86
 
                                   MESA INC.
 
           NOTES TO CONSOLIDATED FINANCIAL STATEMENTS -- (CONTINUED)
 
     The Company periodically enters into natural gas futures contracts as a
hedge against natural gas price fluctuations. Gains or losses on such futures
contracts are deferred and recognized as natural gas revenue when the hedged
production occurs. The Company recognized a gain of $6.2 million related to
hedging activities during the first nine months of 1992 as compared to a loss of
$.3 million for the same period in 1993. At September 30, 1993, the Company had
no deferred gains or losses related to hedging activities and did not own any
natural gas futures contracts accounted for as hedges.
 
TAXES
 
     The Company provides for income taxes using the asset and liability method
under which deferred income taxes are recognized for the tax consequences of
"temporary differences" by applying enacted statutory tax rates applicable to
future years to differences between the financial statement carrying amounts and
the tax bases of existing assets and liabilities. The effect on deferred taxes
of a change in tax laws or tax rates is recognized in income in the period that
includes the enactment date.
 
     On August 10, 1993, the Omnibus Budget Reconciliation Act of 1993 (the Act)
was signed into law resulting in, among other things, an increase in the top
Federal corporate income tax rate from 34% to 35%, effective January 1, 1993.
This and other tax law changes resulting from the Act did not have a material
effect on the Company's net deferred tax asset or related valuation allowance.
Such valuation allowance completely offsets the Company's net deferred tax asset
recorded as of January 1, 1993.
 
     See Note 10 for a discussion of a recent event relating to federal income
taxes.
 
(2) RESOURCES AND LIQUIDITY
 
FINANCIAL CONDITION
 
     At September 30, 1993, the Company's long-term debt, net of current
maturities, totaled $1.2 billion (see Note 4). The Company also had $73.2
million of working capital; cash and securities totaled $122.2 million. Working
capital includes a $37.4 million note receivable, which was collected in October
1993 (see Note 7). Of the $122.2 million of cash and securities, $23.4 million
is held in Hugoton Capital Limited Partnership (HCLP), an indirect subsidiary
partnership. The assets of HCLP, which also holds substantially all of the
Company's Hugoton field natural gas properties, $62.5 million of restricted cash
and $541.6 million of secured debt, are dedicated to service HCLP's debt and are
not available to pay creditors of the Company or its other subsidiaries. See
Note 4 for additional discussion.
 
     The Company's cash flows from operating activities are substantially
dependent on the amount of oil and gas produced and the prices received for such
production. Production and prices received from HCLP properties, together with
cash held within HCLP, are expected, under the Company's current operating plan,
to generate sufficient cash flow to meet HCLP's required principal and interest
obligations. However, HCLP cash flows are not expected to be sufficient to
permit HCLP to distribute any excess cash to Company subsidiaries other than
HCLP until at least 1995. During the third quarter, the Company completed the
debt exchange (Debt Exchange) described in Note 4. The notes issued in the Debt
Exchange replaced substantially all of the Company's $600 million of previously
outstanding long-term subordinated notes. The Debt Exchange will result in the
deferral of annual cash interest payments of approximately $75 million through
June 30, 1995. With the consummation of the Debt Exchange, production and prices
at Company subsidiaries other than HCLP are expected, in the aggregate, to be
sufficient to cover cash interest obligations over the next two years with cash
from operating activities. The Company's subsidiaries other than HCLP may also
supplement cash flows from operating activities with available cash and
securities balances.
 
     Completion of the Debt Exchange also resulted in an amendment to the
majority of the Company's bank credit agreement (Credit Agreement), which
included advancing the maturity of $41 million of principal payments from 1994
to 1993 but also extending the maturity of $40 million of principal and $10
million of
 
                                       F-8
<PAGE>   87
 
                                   MESA INC.
 
           NOTES TO CONSOLIDATED FINANCIAL STATEMENTS -- (CONTINUED)
 
letter of credit obligations from 1994 to 1995. The Company believes that
completion of the Debt Exchange and Credit Agreement amendments have increased
its ability to obtain traditional equity or debt financing in the future to
repay or refinance its indebtedness. Depending on industry conditions, the
Company may also generate or preserve cash by selling assets, reducing capital
expenditures or pursuing other alternatives. As a result of the completion of
the Debt Exchange and the related amendments to the Credit Agreement, the
Company believes that it will have significantly greater cash flow and available
cash balances over the next two to three years, subject to matters discussed
below under "Litigation," whether or not production and prices increase.
 
LONG-TERM DEBT DEFAULT
 
     In conjunction with the negotiation and execution of the Debt Exchange, the
Company did not make the $29.3 million of interest payments due on May 1, 1993
or the $9 million of interest payments due on August 1, 1993 relating to its 12%
and 13 1/2% subordinated notes (Subordinated Notes) resulting in events of
default under the terms of the Subordinated Note indentures and under cross
default provisions of the Credit Agreement. On August 26, 1993, interest
payments with respect to Subordinated Notes which remained outstanding after the
Debt Exchange were made to the trustee under such indentures for distribution to
holders of the remaining Subordinated Notes and, therefore, the events of
default have been cured.
 
LITIGATION
 
     The Company is subject to various lawsuits, the most significant of which
relates to a 1985 investment in Unocal Corporation (Unocal). A trial had been
scheduled to begin February 22, 1994. As described in Note 8, a significant
judgment against the Company in the Unocal lawsuit would have a material adverse
effect on the financial position and results of operations of the Company.
Payment of such a judgment would remove a substantial amount of cash from the
Company at a time when cash flows from operating activities may not be
sufficient to service debt and fund capital expenditures and other obligations.
Such a payment could also reduce tangible adjusted equity, as defined, below the
$50 million level required under the amended Credit Agreement. In the event of
an adverse judgment, the Company could be required to post a bond or other
security in the amount of the judgment in order to stay execution pending any
appeal. See Note 10 for a discussion of recent events relating to the Unocal
litigation.
 
     In the event of an adverse decision, the Company could pursue a variety of
options including sales of assets, settlement discussions to reduce the amount
of the award or to limit bond requests or negotiations to obtain relief from
certain debt obligations to banks or noteholders. The Company could also
consider seeking protection from creditors under the Federal Bankruptcy Code.
The Company's choice from among its alternatives would depend on numerous
factors including the amount of the judgment, bond or security requirements, the
financial condition of the Company and conditions in the oil and gas industry.
 
(3) MARKETABLE SECURITIES
 
     The current value of marketable securities is as follows (in thousands):
 
<TABLE>
<CAPTION>
                                                             SEPTEMBER 30,     DECEMBER 31,
                                                                 1993              1992
                                                             -------------     ------------
        <S>                                                  <C>               <C>
        Cost...............................................     $17,330          $ 12,167
        Unrealized gain (loss).............................         291              (249)
                                                             -------------     ------------
          Market Value.....................................     $17,621          $ 11,918
                                                             -------------     ------------
                                                             -------------     ------------
</TABLE>
 
     For the nine months ended September 30, 1993, the Company recognized a net
gain of $5.8 million from its investments in securities and futures contracts
compared with net gains for the same period in 1992 of
 
                                       F-9
<PAGE>   88
 
                                   MESA INC.
 
           NOTES TO CONSOLIDATED FINANCIAL STATEMENTS -- (CONTINUED)
 
$10.5 million. The net securities gains do not include gains or losses from
natural gas futures contracts accounted for as hedges of natural gas production.
Hedge gains or losses are included in natural gas revenue in the period in which
the hedged production occurs (see Note 1).
 
     The net gains and losses recognized during a period include both realized
and unrealized gains and losses. During the nine month period ended September
30, 1993, the Company realized net gains of $4.6 million from securities
transactions and futures contracts. Net realized gains totaled $5.1 million for
the nine month period ended September 30, 1992.
 
(4) LONG-TERM DEBT
 
     Long-term debt and current maturities are as follows (in thousands):
 
<TABLE>
<CAPTION>
                                                             SEPTEMBER 30,     DECEMBER 31,
                                                                 1993              1992
                                                             -------------     ------------
        <S>                                                  <C>               <C>
        HCLP Secured Notes.................................    $ 541,600        $  580,850
        Credit Agreement...................................       77,862           100,000
        12 3/4% secured discount notes.....................      458,767                --
        12 3/4% unsecured discount notes...................      144,124                --
        0% convertible notes...............................       27,600                --
        12% subordinated notes.............................        6,336           300,000
        13 1/2% subordinated notes.........................        7,390           300,000
        Other..............................................        5,305             5,305
                                                             -------------     ------------
                                                               1,268,984         1,286,155
        Current maturities.................................      (86,371)          (44,555)
                                                             -------------     ------------
        Long-term debt.....................................    $1,182,613       $1,241,600
                                                             -------------     ------------
                                                             -------------     ------------
</TABLE>
 
HCLP SECURED NOTES
 
     In 1991, HCLP, which holds substantially all of the Company's Hugoton field
natural gas properties, issued $616 million of secured notes (HCLP Secured
Notes) in a private placement with a group of institutional lenders. The
issuance replaced $550 million of bank debt and funded a $66 million restricted
cash balance within HCLP. The restricted cash balance is available to supplement
cash flows from the HCLP properties in the event such cash flows are not
sufficient to fund principal and interest payments on the HCLP Secured Notes
when due. As the HCLP Secured Notes are repaid, the required restricted cash
balance is reduced.
 
     The HCLP Secured Notes were issued in 15 series and have final stated
maturities extending through 2012 but can be retired earlier depending on the
rate of production from the Hugoton properties. As of September 30, 1993, $75.0
million has been repaid as scheduled. The HCLP Secured Notes outstanding on
September 30, 1993 bear interest at fixed rates ranging from 8.80% to 11.30%
(weighted average 10.21%). Principal and interest payments are made
semiannually. Provisions in the HCLP Secured Note agreements require interest
rate premiums to be paid to the noteholders in the event that the HCLP Secured
Notes are repaid more rapidly or slowly than scheduled in the agreements. Such
premiums, if required, would increase the effective interest rate of the HCLP
Secured Notes.
 
     The HCLP Secured Note agreements contain various covenants which, among
other things, limit HCLP's ability to sell or acquire oil and gas property
interests, incur additional indebtedness, make unscheduled capital expenditures,
make distributions of property or funds subject to the mortgage, or enter into
certain types of long-term contracts or forward sales of production. The
agreements also require HCLP to maintain separate existence from the Company.
The assets of HCLP are dedicated to service HCLP's debt and are not available to
pay creditors of the Company or its subsidiaries other than HCLP.
 
                                      F-10
<PAGE>   89
 
                                   MESA INC.
 
           NOTES TO CONSOLIDATED FINANCIAL STATEMENTS -- (CONTINUED)
 
     Revenues received from production from HCLP's Hugoton properties are
deposited in a collection account maintained by a collateral agent (Collateral
Agent). The Collateral Agent releases or reserves funds, as appropriate, for the
payment of royalties, taxes, operating costs, capital expenditures and principal
and interest on the HCLP Secured Notes. Only after all required payments have
been made may any remaining funds held by the Collateral Agent be released from
the mortgage.
 
     In connection with the formation of HCLP and the issuance of the HCLP
Secured Notes, Mesa Operating Limited Partnership (MOLP), a direct Company
subsidiary which owns 81% of HCLP, entered into a services agreement with HCLP
pursuant to which MOLP will provide certain services necessary to operate the
Hugoton field properties and market production therefrom, process remittances of
production revenues and perform certain other administrative functions in
exchange for a services fee which totaled approximately $8 million for the nine
months ended September 30, 1993.
 
     The restricted cash balance and cash held by the Collateral Agent for
payment of interest and principal on the HCLP Secured Notes are invested by the
Collateral Agent under the terms of a guaranteed investment contract (GIC) with
Morgan Guaranty Trust Co. of New York (Morgan). Morgan was paid $13.9 million at
the date of issuance of the HCLP Secured Notes to guarantee that funds invested
under the GIC would earn an interest rate equivalent to the weighted average
coupon rate on the outstanding principal balance of the HCLP Secured Notes
(10.21% at September 30, 1993). A portion of this amount may be refunded if the
HCLP Secured Notes are repaid earlier than if HCLP had produced according to its
scheduled production, depending primarily on prevailing interest rates at that
time.
 
     In the first quarter of 1992, the Company contributed $32 million in cash
to HCLP, which amount was not subject to the mortgage, a portion of which has
been used to supplement HCLP's cash flows in order to make scheduled principal
payments. At September 30, 1993, approximately $10.1 million of HCLP's cash was
not subject to the mortgage but is available to be used to supplement HCLP's
cash flow in the future.
 
     HCLP had cash balances as follows (in thousands):
 
<TABLE>
<CAPTION>
                                                             SEPTEMBER 30,     DECEMBER 31,
                                                                 1993              1992
                                                             -------------     ------------
        <S>                                                  <C>               <C>
        Cash included in current assets....................     $23,422          $ 64,141
                                                             -------------     ------------
                                                             -------------     ------------
        Restricted cash included in noncurrent assets......     $62,543          $ 64,339
                                                             -------------     ------------
                                                             -------------     ------------
</TABLE>
 
CREDIT AGREEMENT
 
     As of June 30, 1993, the Company had borrowed $100 million under the $150
million Credit Agreement and had outstanding $10.6 million in letter of credit
obligations secured by the Credit Agreement. The Credit Agreement was previously
scheduled to mature in June 1994. Upon consummation of the Debt Exchange (see
"Discount Notes" below and Note 2), the Company and its bank lenders amended the
Credit Agreement. Pursuant to the amendment, the Credit Agreement was reduced to
a $90 million credit facility providing for $80 million of initial borrowings
and $10 million in letter of credit obligations. Accordingly, the Company made a
$20 million principal payment under the Credit Agreement on August 26, 1993 and
agreed to make additional principal payments of $10 million in the fourth
quarter of 1993, $30 million in the first half of 1994, $40 million in the
second quarter of 1995, and to cash collateralize $10 million in letters of
credit obligations in the second quarter of 1995.
 
     The terms of the Credit Agreement require prepayment with respect to the
next principal payment due in the amount of one-half of any proceeds from
collections under the note receivable from Bicoastal Corporation (Bicoastal)
(see Note 7). As a result of collections from Bicoastal totaling $41.0 million
in the third and fourth quarters of 1993, $10.5 million of the $30 million due
in the first half of 1994 will be prepaid in the fourth quarter of 1993.
 
                                      F-11
<PAGE>   90
 
                                   MESA INC.
 
           NOTES TO CONSOLIDATED FINANCIAL STATEMENTS -- (CONTINUED)
 
     The rate of interest payable on borrowings under the Credit Agreement is
the prime rate plus  1/2% or the Eurodollar rate plus 2 1/2% until borrowings
are reduced to $50 million, and thereafter reduced, subject to certain
conditions, to a rate equal to the Eurodollar rate plus 1 1/2% or the prime
rate. The Credit Agreement is secured by a first lien on the Company's West
Panhandle field properties, by the Company's equity interest in MOLP and by a
65% equity interest in HCLP.
 
     The amendments to the Credit Agreement reduced the Company's tangible
adjusted equity requirement, as defined, from $150 million to $50 million and
increased the Company's required ratio of cash flow and available cash to debt
service requirement, as each is defined, from at least 1.25 to 1 to 1.50 to 1.
At September 30, 1993, the Company's tangible adjusted equity, as defined, was
$132 million and the ratio of cash flow and available cash to debt service was
2.11 to 1.
 
     The provisions of the Credit Agreement prohibit the Company from paying any
dividends to equity holders, other than those paid in the form of equity
securities.
 
DISCOUNT NOTES
 
     The Debt Exchange was consummated on August 26, 1993. Under the terms of
the Debt Exchange, holders of approximately $293.7 million aggregate principal
amount of 12% subordinated notes and $292.6 million aggregate principal amount
of 13 1/2% subordinated notes (together with $28.6 million of accrued interest
claims thereon) received approximately $435.5 million initial accreted value, as
defined, of 12 3/4% secured discount notes due June 30, 1998; $136.9 million
initial accreted value, as defined, of 12 3/4% unsecured discount notes due June
30, 1996 (together, the Discount Notes); $29.3 million principal amount of 0%
convertible notes due June 30, 1998 (collectively, the New Notes); and, in the
case of 13 1/2% subordinated noteholders, $13.2 million in cash. The New Notes,
which rank pari passu with each other, are senior in right of payment to the
remaining Subordinated Notes and subordinate to all permitted first lien debt,
including the Credit Agreement.
 
     The Discount Notes will bear no interest through June 30, 1995; however,
the accreted value, as defined, of both series will increase from May 1, 1993
through June 30, 1995 at 12 3/4% per year, compounded semiannually, with the
first compounding date being June 30, 1993. After June 30, 1995, each series
will accrue interest at an annual rate of 12 3/4%, payable in cash semiannually
in arrears, with the first payment due December 31, 1995. The 0% convertible
notes bear no interest and are convertible at the option of the noteholders at
any time into shares of the Company's common stock at the rate of $3.896 per
share. As of September 30, 1993, $1.7 million of the 0% convertible notes had
been converted into 439,923 shares of common stock. If not earlier converted,
and subject to certain conditions, the 0% convertible notes are subject to
conversion at the option of the Company after November 25, 1993. The Company
intends to cause such conversion of any remaining 0% convertible notes before
December 31, 1993.
 
     The 12 3/4% secured discount notes are secured by second liens on the
Company's West Panhandle field properties and a 65% equity interest in HCLP,
both of which currently secure the Credit Agreement. The Company's right to
maintain first lien debt is limited to $82.5 million.
 
     The indentures governing the Discount Notes, among other things, restrict
the Company's ability to incur additional indebtedness, pay dividends, acquire
stock or make investments, loans and advances.
 
SUBORDINATED NOTES
 
     The 12% subordinated notes are unsecured and mature in 1996. Interest on
these notes is payable quarterly and, at the option of the Company, may be paid
in Common Stock of the Company. The 13 1/2% subordinated notes are unsecured and
mature in 1999. Interest on these notes is payable semiannually in cash.
 
                                      F-12
<PAGE>   91
 
                                   MESA INC.
 
           NOTES TO CONSOLIDATED FINANCIAL STATEMENTS -- (CONTINUED)
 
INTEREST AND MATURITIES
 
     The aggregate interest payments made during the nine months ended September
30, 1993 and 1992 were $86.0 million and $111.8 million, respectively.
Approximately $45.9 million of interest incurred during the nine months ended
September 30, 1993 has been deferred under the terms of the Debt Exchange until
the repayment dates of the Discount Notes. Such interest is included in interest
expense in the statement of operations.
 
     The scheduled repayments on long-term debt for the last three months of
1993 and for the four succeeding years are as follows (in millions):
 
<TABLE>
<CAPTION>
                                                        1993    1994    1995     1996    1997
                                                        -----   -----   -----   ------   -----
    <S>                                                 <C>     <C>     <C>     <C>      <C>
    HCLP Secured Notes................................  $  --   $42.9   $39.3   $ 45.4   $46.7
    Credit Agreement(1)...............................   18.7    19.5    39.6       --      --
    12 3/4% unsecured discount notes..................     --      --      --    178.8      --
    12% subordinated notes............................     --      --      --      6.3      --
    Other.............................................    5.3      --      --       --      --
                                                        -----   -----   -----   ------   -----
              Total...................................  $24.0   $62.4   $78.9   $230.5   $46.7
                                                        -----   -----   -----   ------   -----
                                                        -----   -----   -----   ------   -----
</TABLE>
 
- ---------------
 
(1) Excludes $10 million in letter of credit obligations required to be cash
collateralized in 1995.
 
FAIR VALUE OF LONG-TERM DEBT
 
     Based on borrowing rates currently available for secured debt with similar
maturities and credit rating, the fair value of the HCLP Secured Notes at
September 30, 1993 is estimated to be approximately $623 million.
 
     Based on borrowing rates currently available for bank loans with similar
collateral, the fair value of the borrowings under the Credit Agreement at
September 30, 1993 is estimated to be its carrying value.
 
     The Discount Notes are publicly traded but not listed on a national
exchange. Based on trading prices available at September 30, 1993, the fair
value of the 12 3/4% secured discount notes was $464.0 million and the fair
value of the 12 3/4% unsecured discount notes was $137.7 million.
 
     The 12% and 13 1/2% subordinated notes are publicly traded but have not
experienced significant activity since consummation of the Debt Exchange. Based
on recent trades, the fair value of the 12% and 13 1/2% subordinated notes is
not materially different from their carrying value.
 
     Based on the current financial condition of the Company, there is no
assurance that the Company could obtain borrowings under long-term debt
agreements with terms similar to those described above and receive proceeds
approximating the estimated fair values.
 
(5) PROPERTY SALES
 
     On April 30, 1993, the Company sold a portion of its Rocky Mountain area
properties for $7.1 million, after adjustments, and recorded a gain on the sale
of approximately $4.1 million. The Company also retained a reversionary interest
in the properties under which the Company will receive a 50% net profits
interest in the properties after the purchaser has recovered its investment and
certain other costs and expenses.
 
     On June 24, 1993, the Company sold its interest in the deep portion of the
Hugoton field not owned by HCLP for approximately $19 million, after
adjustments, and recorded a gain on the sale of approximately $5.5 million.
 
                                      F-13
<PAGE>   92
 
                                   MESA INC.
 
           NOTES TO CONSOLIDATED FINANCIAL STATEMENTS -- (CONTINUED)
 
     These properties were expected to contribute approximately $5 million to
the Company's 1993 cash flows. The proceeds from these sales were added to
available cash.
 
(6) STOCKHOLDERS' EQUITY
 
     At September 30, 1993, the Company had outstanding 39.0 million shares of
common stock and the Company owned a 95.90% limited partnership interest in its
direct subsidiary partnerships and the General Partner owned a 4.10% interest.
The General Partner's interest is convertible into approximately 1.7 million
shares of common stock. See Note 10 for a discussion of recent events affecting
the General Partner's interest and the Company's subsidiary partnerships.
 
     Approximately $1.7 million of 0% convertible notes were converted into
439,923 shares of common stock in September 1993. Approximately 7.1 million
additional shares of common stock are issuable in exchange for the remaining
$27.6 million of 0% convertible notes. See Notes 2 and 4 for a discussion of the
Debt Exchange.
 
     The Company also has authorized 10 million shares of preferred stock. No
shares of preferred stock have been issued as of September 30, 1993.
 
(7) NOTES RECEIVABLE
 
     As of September 30, 1993, notes receivable consist entirely of claims
against Bicoastal. A plan of reorganization for Bicoastal was approved by the
Bankruptcy Court in September 1992 and the Company collected approximately $28.1
million in 1992 and $3.6 million in July 1993. At September 30, 1993, the
Company had remaining allowed principal claims of $37.4 million which were
collected in October 1993. The October 1993 collection resulted in a third
quarter gain of approximately $13.8 million, which represented the amount of
proceeds collected in excess of the recorded note receivable. The Company may
also collect certain interest amounts, although the timing and amount of such
collection, if any, is uncertain.
 
(8) CONTINGENCIES
 
UNOCAL
 
     The Company is subject to a lawsuit relating to the investment in Unocal by
Original Mesa and certain other defendants (collectively, the Mesa Defendants).
This suit, filed in 1986 in Federal District Court in Los Angeles, alleges that,
pursuant to Section 16(b) of the Securities Exchange Act of 1934, "short-swing
profits" allegedly realized by the Mesa Defendants upon disposition of certain
shares of Unocal common stock in 1985 are recoverable by Unocal. The case is
currently scheduled to begin trial on February 22, 1994. The Company will have
no liability in the case if it prevails on either of the following grounds: (i)
that the 1985 acquisition of 6.7 million shares of Unocal was, as the Company
contends, effected in a single purchase, or (ii) that the Mesa Defendants
realized no profit on the disposition of any Unocal shares that might be deemed
subject to Section 16(b).
 
     No determination can be made at this time as to the ultimate outcome of the
litigation. If the plaintiffs were to prevail and were awarded a judgment
(including interest) in the range of their estimate of $150 million, payment of
such damages would have a material adverse effect on the financial position and
results of operations of the Company. Consequences to the Company of an adverse
decision are discussed in Note 2. See Note 10 for a discussion of recent events
relating to the Unocal litigation.
 
MASTERSON
 
     In February 1992, the current lessors of an oil and gas lease (the Gas
Lease) dated April 30, 1955, between R. B. Masterson, et al., as lessor, and
Colorado Interstate Gas Company (CIG), as lessee, sued CIG in Federal District
Court in Amarillo, Texas, claiming that CIG had underpaid royalties due under
the Gas
 
                                      F-14
<PAGE>   93
 
                                   MESA INC.
 
           NOTES TO CONSOLIDATED FINANCIAL STATEMENTS -- (CONTINUED)
 
Lease. The Company owns an interest in the Gas Lease. The plaintiffs alleged
that the underpayment was the result of CIG's use of an improper gas sales price
upon which to calculate royalties, and that the proper price should have been
determined pursuant to a pricing clause in a July 1, 1967 amendment to the Gas
Lease. The complaint did not specify the damages sought and appeared to relate
only to royalties for periods after October 1, 1988. The plaintiffs also sought
a declaration by the court as to the proper price to be used for calculating
future royalties.
 
     In August 1992, CIG filed a third-party complaint against the Company for
any such royalty underpayments which may be allocable to the Company's interest
in the Gas Lease.
 
     On December 22, 1992, the plaintiffs filed a Second Amended Complaint,
including both CIG and the Company as defendants, again alleging that the use of
an improper price in calculating royalties resulted in underpayments of royalty,
but for the first time alleging that the underpayments amounted to approximately
$250 million (including interest) and covered the period July 1, 1967 to
present. In addition, the plaintiffs seek exemplary damages.
 
     The plaintiffs have dismissed their claims against the Company for reasons
relating to the jurisdiction of the federal court; however, the third-party
complaint by CIG against the Company is not affected by the dismissal.
 
     The plaintiffs have recently filed court papers alleging royalty
underpayments of approximately $450 million (including interest at 10%) covering
the period July 1, 1967 to the present. In addition, the plaintiffs seek
exemplary damages. Management believes that the Company has several defenses to
plaintiffs' claims, including (i) that the royalties for all periods were
properly computed and paid and (ii) that plaintiffs' claims with respect to all
periods prior to October 1, 1988 (which appear to account for the substantial
portion of the claims) were explicitly released by a 1988 written agreement
among plaintiffs, CIG and the Company and are further barred by the statute of
limitations. If the plaintiffs were to prevail, the manner in which any
resulting liability would be shared between the Company and CIG would depend on
the resolution of issues relating to the contractual agreements and the
relationship between the Company, CIG and the lessors during the period in
question.
 
     No determination can be made at this time as to the ultimate outcome of the
litigation and no trial date has been set.
 
PREFERENCE UNITHOLDERS
 
     The Company is a defendant in lawsuits related to the Corporate Conversion
pending in the U.S. District Court for the Northern District of Texas -- Dallas
Division. Plaintiffs allege, among other things, that (i) the proxy materials
delivered to unitholders in connection with the Corporate Conversion contained
material misstatements and omissions, (ii) the general partner of the
Partnership breached fiduciary duties to the preference unitholders in
structuring the transaction and allocating the common stock of the Company and
(iii) the Corporate Conversion was not properly approved by the unitholders of
the Partnership because certain procedural requirements of the partnership
agreement were allegedly not met. The Company and the other defendants have
denied the allegations and believe they are without merit. Plaintiffs seek an
order requiring payment to the former preference unitholders of $164 million in
respect of the preferential distribution rights of their units, a declaration
declaring the Corporate Conversion void and rescinding it, unspecified
compensatory and punitive damages and other relief.
 
OTHER
 
     The Company is also a defendant in other lawsuits and has assumed
liabilities relating to Original Mesa and the Partnership. The Company does not
expect the resolution of the Masterson lawsuit and preference
 
                                      F-15
<PAGE>   94
 
                                   MESA INC.
 
           NOTES TO CONSOLIDATED FINANCIAL STATEMENTS -- (CONTINUED)
 
unitholder lawsuits or any of these other matters to have a material effect on
its financial position or results of operations.
 
(9) CONDENSED CONSOLIDATING FINANCIAL STATEMENTS
 
     The Company conducts its operations through various direct and indirect
subsidiaries. The Company's direct subsidiaries are MOLP, Mesa Midcontinent
Limited Partnership (MMLP)and Mesa Holding Limited Partnership (MHLP). MOLP owns
all of the Company's interest in the West Panhandle field of Texas, the Gulf
Coast and the Rocky Mountain area, as well as an approximate 81% limited
partnership interest in HCLP. MMLP owns an approximate 19% limited partnership
interest in HCLP. HCLP owns substantially all of the Company's Hugoton field
natural gas properties and is liable for the HCLP Secured Notes (see Note 4).
The assets and cash flows of HCLP are dedicated to service the HCLP Secured
Notes and are not available to pay creditors of the Company or its subsidiaries
other than HCLP. MOLP and the Company are liable for the Credit Agreement, the
Subordinated Notes and the New Notes. Mesa Capital Corp. (Mesa Capital), a
wholly owned subsidiary of MOLP, is also an obligor under the Subordinated Notes
and the New Notes. Mesa Capital is a financing subsidiary and has insignificant
assets and results of operations. Mesa Capital is included with MOLP in the
condensed consolidating financial statements. See Note 10 for a discussion of
recent events affecting the Company's subsidiary partnerships.
 
                                      F-16
<PAGE>   95
 
                                   MESA INC.
 
           NOTES TO CONSOLIDATED FINANCIAL STATEMENTS -- (CONTINUED)
 
     The following are condensed consolidating financial statements of MESA
Inc., HCLP, MOLP and the Company's other direct and indirect subsidiaries
combined (in millions):
 
CONDENSED CONSOLIDATING BALANCE SHEETS
 
<TABLE>
<CAPTION>
                                                                 OTHER       CONSOLIDATION       THE
                                         MESA                   COMPANY           AND          COMPANY
SEPTEMBER 30, 1993                       INC.   HCLP   MOLP   SUBSIDIARIES    ELIMINATION    CONSOLIDATED
- ------------------                       ----   ----   ----   ------------   -------------   ------------
<S>                                      <C>    <C>    <C>    <C>            <C>             <C>
Assets:
  Cash and cash investments............  $ --   $ 23   $ 15       $ 67           $  --          $  105
  Other current assets.................    --     12     29         53              --              94
                                         ----   ----   ----       ----           -----          ------
     Total current assets..............    --     35     44        120              --             199
                                         ----   ----   ----       ----           -----          ------
  Property, plant and equipment, net...    --    665    551          1              --           1,217
  Investment in subsidiaries...........   136     --     41        189            (366)             --
  Intercompany receivables.............    --     --    138         --            (138)             --
  Other noncurrent assets..............    --     88     53          3              --             144
                                         ----   ----   ----       ----           -----          ------
                                         $136   $788   $827       $313           $(504)         $1,560
                                         ----   ----   ----       ----           -----          ------
                                         ----   ----   ----       ----           -----          ------
Liabilities and Equity:
  Current liabilities..................  $ --   $ 58   $ 66       $  2           $  --          $  126
  Long-term debt.......................    --    499    684         --              --           1,183
  Intercompany payables................     9     --     --        148            (157)             --
  Other noncurrent liabilities.........    --     --    106         13              --             119
  Minority interest....................    --     --     --         --               5               5
  Partners'/Stockholders' equity
     (deficit).........................   127    231    (29)       150            (352)            127
                                         ----   ----   ----       ----           -----          ------
                                         $136   $788   $827       $313           $(504)         $1,560
                                         ----   ----   ----       ----           -----          ------
                                         ----   ----   ----       ----           -----          ------
DECEMBER 31, 1992
- -----------------
Assets:
  Cash and cash investments............  $ --   $ 64   $ 16       $ 77           $  --          $  157
  Other current assets.................    --     22     31          9              --              62
                                         ----   ----   ----       ----           -----          ------
     Total current assets..............    --     86     47         86              --             219
                                         ----   ----   ----       ----           -----          ------
  Property, plant and equipment, net...    --    682    598         --              --           1,280
  Investment in subsidiaries...........   193     --     51        191            (435)             --
  Intercompany receivables.............    --     --    138         --            (138)             --
  Other noncurrent assets..............    --     91     56         30              --             177
                                         ----   ----   ----       ----           -----          ------
                                         $193   $859   $890       $307           $(573)         $1,676
                                         ----   ----   ----       ----           -----          ------
                                         ----   ----   ----       ----           -----          ------
Liabilities and Equity:
  Current liabilities..................  $ --   $ 74   $ 40       $  2           $  --          $  116
  Long-term debt.......................    --    542    700         --              --           1,242
  Intercompany payables................     9     --     --        142            (151)             --
  Other noncurrent liabilities.........    --     --    113         13              --             126
  Minority interest....................    --     --     --         --               8               8
  Partners'/Stockholders' equity
     (deficit).........................   184    243     37        150            (430)            184
                                         ----   ----   ----       ----           -----          ------
                                         $193   $859   $890       $307           $(573)         $1,676
                                         ----   ----   ----       ----           -----          ------
                                         ----   ----   ----       ----           -----          ------
</TABLE>
 
                                      F-17
<PAGE>   96
 
                                   MESA INC.
 
           NOTES TO CONSOLIDATED FINANCIAL STATEMENTS -- (CONTINUED)
 
CONDENSED CONSOLIDATING STATEMENTS OF OPERATIONS
 
NINE MONTHS ENDED:
 
<TABLE>
<CAPTION>
                                                                 OTHER       CONSOLIDATION       THE
                                         MESA                   COMPANY           AND          COMPANY
SEPTEMBER 30, 1993                       INC.   HCLP   MOLP   SUBSIDIARIES    ELIMINATION    CONSOLIDATED
- ------------------                       ----   ----   ----   ------------   -------------   ------------
<S>                                      <C>    <C>    <C>    <C>            <C>             <C>
Revenues...............................  $--    $ 68   $ 89       $ --            $ --           $157
                                         ----   ----   ----       ----            ----           ----
Costs and Expenses:
  Operating, exploration and taxes.....   --      19     37         --              --             56
  General and administrative...........   --     --      15          2              --             17
  Depreciation, depletion and
     amortization......................   --      23     47         --              --             70
                                         ----   ----   ----       ----            ----           ----
                                          --      42     99          2              --            143
                                         ----   ----   ----       ----            ----           ----
Operating Income (Loss)................   --      26    (10)        (2)             --             14
                                         ----   ----   ----       ----            ----           ----
Interest Expense, Net of Interest
  Income...............................   --     (37)   (61)         1              --            (97)
Intercompany Interest Income
  (Expense)............................   --     --      12        (12)             --             --
Security Gains (Losses)................   --     --       7         (1)             --              6
Equity in Loss of Subsidiaries.........   (59)   --      (9)        (2)             70             --
Minority Interest......................   --     --     --          --               3              3
Other..................................   --     --      (7)        17               5             15
                                         ----   ----   ----       ----            ----           ----
Net Income (Loss)......................  $(59)  $(11)  $(68)      $  1            $ 78           $(59)
                                         ----   ----   ----       ----            ----           ----
                                         ----   ----   ----       ----            ----           ----
SEPTEMBER 30, 1992
- ------------------
Revenues...............................  $--    $ 50   $109       $ --            $ --           $159
                                         ----   ----   ----       ----            ----           ----
Costs and Expenses:
  Operating, exploration and taxes.....   --      15     38         --              --             53
  General and administrative...........   --     --      19         --              --             19
  Depreciation, depletion and
     amortization......................   --      23     57         --              --             80
                                         ----   ----   ----       ----            ----           ----
                                          --      38    114         --              --            152
                                         ----   ----   ----       ----            ----           ----
Operating Income (Loss)................   --      12     (5)        --              --              7
                                         ----   ----   ----       ----            ----           ----
Interest Expense, Net of Interest
  Income...............................   --     (39)   (60)         2              --            (97)
Intercompany Interest Income
  (Expense)............................   --     --      13        (13)             --             --
Security Gains.........................   --     --       5          6              --             11
Equity in Loss of Subsidiaries.........   (70)   --     (22)        (5)             97             --
Minority Interest......................   --     --     --          --               3              3
Other..................................    (2)   --      (1)        (2)              9              4
                                         ----   ----   ----       ----            ----           ----
Net Loss...............................  $(72)  $(27)  $(70)      $(12)           $109           $(72)
                                         ----   ----   ----       ----            ----           ----
                                         ----   ----   ----       ----            ----           ----
</TABLE>
 
                                      F-18

<PAGE>   97
 
                                   MESA INC.
 
           NOTES TO CONSOLIDATED FINANCIAL STATEMENTS -- (CONTINUED)
 
CONDENSED CONSOLIDATING STATEMENTS OF CASH FLOWS
 
NINE MONTHS ENDED:
 
<TABLE>
<CAPTION>
                                                                 OTHER       CONSOLIDATION       THE
                                         MESA                   COMPANY           AND          COMPANY
SEPTEMBER 30, 1993                       INC.   HCLP   MOLP   SUBSIDIARIES    ELIMINATION    CONSOLIDATED
- ------------------                       ----   ----   ----   ------------   -------------   ------------
<S>                                      <C>    <C>    <C>    <C>            <C>             <C>
Cash Flows from Operating Activities...  $--    $  3    $ 8       $  1         $    --             $ 12
                                         ----   ----   ----     ------         --------          ------
Cash Flows from Investing Activities:
  Capital expenditures.................   --      (6)   (15)        (1)             --              (22)
  Proceeds from sales of oil and gas
     properties........................   --     --      23          3              --               26
  Securities transactions, net.........   --     --       9         (9)             --              --
  Other................................   --     --       4          2               (6)            --
                                         ----   ----   ----     ------         --------          ------
                                          --      (6)    21         (5)              (6)              4
                                         ----   ----   ----     ------         --------          ------
Cash Flows from Financing Activities:
  Repayments of long-term debt.........   --     (39)   (22)       --               --              (61)
  Other................................   --       2     (9)        (6)               6              (7)
                                         ----   ----   ----     ------         --------          ------
                                          --     (37)   (31)        (6)               6             (68)
                                         ----   ----   ----     ------         --------          ------
Net Decrease in Cash and Cash
  Investments..........................  $--    $(40)   $(2)      $(10)          $  --             $(52)
                                         ----   ----   ----     ------         --------          ------
                                         ----   ----   ----     ------         --------          ------
SEPTEMBER 30, 1992
- ------------------
Cash Flows from Operating Activities...  $--     $(8)  $(28)      $  3           $  --             $(33)
                                         ----   ----   ----     ------         --------          ------
Cash Flows from Investing Activities:
  Capital expenditures.................   --      (2)   (55)        --              --              (57)
  Proceeds from sales of oil and gas
     properties........................   --     --      11         --              --               11
  Securities transactions, net.........   --     --      (3)        (2)             --               (5)
  Contributions to subsidiaries........   --     --     (25)        (7)              32             --
  Other................................   --     --       7         22              (14)             15
                                         ----   ----   ----     ------         --------          ------
                                          --      (2)   (65)        13               18             (36)
                                         ----   ----   ----     ------         --------          ------
Cash Flows from Financing Activities:
  Repayments of long-term debt.........   --     (25)    --        --               --              (25)
  Contributions from equityholders.....   --      32     --        --               (32)            --
  Other................................   --      (1)    (2)       (14)              14              (3)
                                         ----   ----   ----     ------         --------          ------
                                          --       6     (2)       (14)             (18)            (28)
                                         ----   ----   ----     ------         --------          ------
Net Increase (Decrease) in Cash and
  Cash Investments.....................  $--     $(4)  $(95)      $  2           $  --             $(97)
                                         ----   ----   ----     ------         --------          ------
                                         ----   ----   ----     ------         --------          ------
</TABLE>
 
NOTES TO CONDENSED CONSOLIDATING FINANCIAL STATEMENTS
 
(a) These condensed consolidated financial statements should be read in
     conjunction with the consolidated financial statements and notes thereto of
     the Company of which this note is an integral part.
 
(b) As of September 30, 1993, MESA Inc. owns a 95.90% limited partnership
     interest in each of MOLP, MMLP and MHLP. The General Partner owns 4.10% of
     each of these subsidiary partnerships. These condensed consolidating
     financial statements present MESA Inc.'s investment in its subsidiaries and
     MOLP's and MMLP's investments in HCLP using the equity method. Under this
     method, investments are recorded at cost and adjusted for the parent
     company's ownership share of the subsidiary's cumulative results of
     operations. In addition, investments increase in the amount of
     contributions to subsidiaries and decrease in the amount of distributions
     from subsidiaries.
 
(c) The consolidation and elimination entries (i) eliminate the equity method
     investment in subsidiaries and equity in loss of subsidiaries, (ii)
     eliminate the intercompany payables and receivables, (iii) eliminate other
     transactions between subsidiaries including contributions and distributions
     and (iv) establish the General Partner's minority interest in the
     consolidated results of operations and financial position of the Company.
 
                                      F-19
<PAGE>   98
 
                                   MESA INC.
 
           NOTES TO CONSOLIDATED FINANCIAL STATEMENTS -- (CONTINUED)
 
(10) SUBSEQUENT EVENTS
 
  Unocal Settlement
 
     On January 11, 1994, the Company entered into a settlement agreement with
respect to the Unocal lawsuit described in Note 8 above, whereby the Company and
the other defendants have agreed to pay to Unocal an aggregate of $47.5 million,
of which $42.75 million will be paid by the Company and $4.75 million will be
paid by certain other unaffiliated third parties. The settlement agreement is
subject to approval by the Court, following notice by Unocal to its security
holders. The Company intends to fund substantially all of its portion of the
settlement amount with proceeds from issuance of additional 12 3/4% secured
discount notes. If the settlement agreement is not approved by the Court, the
agreement will terminate and the parties will jointly request the Court to set
the earliest practicable trial date. The Company expects to accrue a loss in the
amount of its share of the settlement in the fourth quarter of 1993.
 
  Stockholders' Equity/Minority Interest
 
     During the fourth quarter of 1993, the remaining 0% convertible notes
outstanding at September 30, 1993 in the amount of $27.6 million were converted
into approximately 7.1 million shares of common stock of the Company.
 
     On December 31, 1993, the General Partner exercised his right to convert a
portion of his general partner interests in the direct subsidiary partnerships
into shares of common stock of the Company, converting approximately one-fourth
of his general partner interests into an aggregate of 416,890 shares of common
stock. On January 5, 1994, the Company effected a series of merger transactions
which resulted in the conversion of each of its subsidiary partnerships, other
than HCLP, to corporate form. Pursuant to these mergers, MOLP was merged into
Mesa Operating Co., MMLP was merged into Mesa Midcontinent Co., and MHLP was
merged into Mesa Holding Co. Pursuant to these mergers, all of the remaining
general partnership interests in the Company's subsidiary partnerships held
directly or indirectly by the General Partner were converted into an aggregate
of 1,250,670 shares of common stock, thereby eliminating the minority interest.
 
  Taxes
 
     In 1993, the Internal Revenue Service (IRS) completed two field
examinations of the tax returns filed by Original Mesa for 1984 through 1987 tax
years. In the fourth quarter of 1993, the IRS completed its administrative
review of the field examinations and presented the Company with an additional
tax assessment of approximately $7.7 million. In December 1993, the Company made
a payment to the IRS of approximately $13 million, which payment includes
interest, in full settlement of all claims. The Company is fully reserved for
the additional tax assessment relating to the 1984 through 1987 tax years.
 
                                      F-20
<PAGE>   99
 
                    REPORT OF INDEPENDENT PUBLIC ACCOUNTANTS
 
To MESA Inc.:
 
     We have audited the accompanying consolidated balance sheets of MESA Inc.
(a Texas corporation) as of December 31, 1992 and 1991, and the related
consolidated statements of operations, cash flows and changes in stockholders'
equity for each of the three years in the period ended December 31, 1992. These
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 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 audits provide a reasonable basis for our opinion.
 
     As discussed further in Note 14 to the consolidated financial statements,
the Company has prepared financial forecasts which indicate that the Company's
cash flows from operating activities and existing cash and securities balances
will be insufficient to fund certain principal and interest payments in 1996 on
the Company's debt. Depending on industry and market conditions, the Company may
generate cash by selling assets or issuing new debt or equity securities.
However, the Company has a limited ability to sell assets and there can be no
assurances that the Company will be able to raise equity capital or otherwise
refinance its debt.
 
     In our opinion, the consolidated financial statements referred to above
present fairly, in all material respects, the financial position of MESA Inc. as
of December 31, 1992 and 1991, and the results of its operations and its cash
flows for each of the three years in the period ended December 31, 1992, in
conformity with generally accepted accounting principles.
 
     As discussed further in Notes 2 and 9 to the consolidated financial
statements, the Company is subject to a lawsuit asserting that "short-swing
profits" allegedly realized upon disposition of certain shares of Unocal
Corporation (Unocal) common stock are recoverable by Unocal pursuant to Section
16(b) of the Securities Exchange Act of 1934. No determination can be made at
this time as to the ultimate outcome of the litigation. Accordingly, no
provision for any liability that may result upon adjudication has been made in
the accompanying consolidated financial statements. As discussed in Notes 2 and
9, an unfavorable judgment would have a material adverse effect on the Company's
financial position and results of operations. As discussed further in Note 14 to
the consolidated financial statements, the Company and Unocal have entered into
a settlement agreement with respect to the Unocal lawsuit. No determination can
be made at this time as to whether the terms of the settlement agreement will be
met or whether the settlement will be consummated.
 
                                            ARTHUR ANDERSEN & CO.
 
Houston, Texas
March 12, 1993 (except with respect to
  the matters discussed in Note 14, as to
  which the date is January 13, 1994)
 
                                      F-21
<PAGE>   100
 
                                   MESA INC.
 
                     CONSOLIDATED STATEMENTS OF OPERATIONS
                            YEARS ENDED DECEMBER 31
                     (IN THOUSANDS, EXCEPT PER SHARE DATA)
 
<TABLE>
<CAPTION>
                                                            1992          1991          1990
                                                          ---------     ---------     ---------
<S>                                                       <C>           <C>           <C>
REVENUES:
  Natural gas...........................................  $ 157,672     $ 169,907     $ 232,220
  Natural gas liquids...................................     59,669        62,031        55,507
  Oil and condensate....................................     18,701        16,111        33,780
  Other.................................................      1,070         1,497         8,090
                                                          ---------     ---------     ---------
                                                            237,112       249,546       329,597
                                                          ---------     ---------     ---------
COSTS AND EXPENSES:
  Lease operating.......................................     43,859        46,869        61,381
  Production and other taxes............................     18,631        18,945        24,828
  Exploration charges...................................     10,008         4,691         8,507
  General and administrative............................     24,460        27,837        27,711
  Depreciation, depletion and amortization..............    113,933       117,076       163,781
                                                          ---------     ---------     ---------
                                                            210,891       215,418       286,208
                                                          ---------     ---------     ---------
OPERATING INCOME........................................     26,221        34,128        43,389
                                                          ---------     ---------     ---------
OTHER INCOME (EXPENSE):
  Interest income.......................................     13,504        16,512        16,444
  Interest expense......................................   (143,392)     (150,770)     (186,700)
  Gains (losses) on dispositions of oil and gas
     properties.........................................     12,250        33,749       (81,029)
  Securities gains (losses).............................      7,808        (2,060)         (452)
  Minority interest in loss.............................      3,854         3,419         8,649
  Other.................................................     (9,477)      (14,141)         (577)
                                                          ---------     ---------     ---------
                                                           (115,453)     (113,291)     (243,665)
                                                          ---------     ---------     ---------
NET LOSS................................................  $ (89,232)    $ (79,163)    $(200,276)
                                                          ---------     ---------     ---------
                                                          ---------     ---------     ---------
NET LOSS PER COMMON SHARE...............................  $   (2.31)    $   (2.05)    $   (5.19)
                                                          ---------     ---------     ---------
                                                          ---------     ---------     ---------
DIVIDENDS PER COMMON SHARE..............................  $      --     $      --     $     .85
                                                          ---------     ---------     ---------
                                                          ---------     ---------     ---------
AVERAGE COMMON SHARES OUTSTANDING.......................     38,571        38,571        38,571
                                                          ---------     ---------     ---------
                                                          ---------     ---------     ---------
</TABLE>
 
         (See accompanying notes to consolidated financial statements)
(The consolidated statements of operations reflect the reorganization described
                                  in Note 1.)
 
                                      F-22
<PAGE>   101
 
                                   MESA INC.
 
                          CONSOLIDATED BALANCE SHEETS
                                  DECEMBER 31
                       (IN THOUSANDS, EXCEPT SHARE DATA)
 
                                     ASSETS
 
<TABLE>
<CAPTION>
                                                                        1992          1991
                                                                      ----------    ----------
<S>                                                                   <C>           <C>
CURRENT ASSETS:
  Cash and cash investments.........................................  $  157,197    $  232,155
  Marketable securities.............................................      11,918        28,183
  Accounts receivable...............................................      44,637        44,005
  Other.............................................................       5,498         5,107
                                                                      ----------    ----------
          Total current assets......................................     219,250       309,450
                                                                      ----------    ----------
PROPERTY, PLANT AND EQUIPMENT:
  Oil and gas properties, wells and equipment, using the successful
     efforts method of accounting...................................   1,851,555     1,790,224
  Office and other..................................................      40,601        41,861
  Accumulated depreciation, depletion and amortization..............    (611,905)     (501,809)
                                                                      ----------    ----------
                                                                       1,280,251     1,330,276
                                                                      ----------    ----------
OTHER ASSETS:
  Restricted cash of subsidiary partnership.........................      64,339        65,381
  Notes receivable..................................................      30,315        58,496
  Gas balancing receivable..........................................      42,089        23,888
  Other.............................................................      40,279        45,325
                                                                      ----------    ----------
                                                                         177,022       193,090
                                                                      ----------    ----------
                                                                      $1,676,523    $1,832,816
                                                                      ----------    ----------
                                                                      ----------    ----------
                            LIABILITIES AND STOCKHOLDERS' EQUITY
CURRENT LIABILITIES:
  Current maturities on long-term debt..............................  $   44,555    $    6,310
  Accounts payable and accrued liabilities..........................      39,397        53,164
  Interest payable..................................................      32,445        33,101
                                                                      ----------    ----------
          Total current liabilities.................................     116,397        92,575
                                                                      ----------    ----------
LONG-TERM DEBT......................................................   1,241,600     1,304,395
                                                                      ----------    ----------
DEFERRED REVENUE....................................................      25,982        36,203
                                                                      ----------    ----------
OTHER LIABILITIES...................................................     100,231       114,244
                                                                      ----------    ----------
CONTINGENCIES
MINORITY INTEREST...................................................       7,961        11,815
                                                                      ----------    ----------
STOCKHOLDERS' EQUITY:
  Preferred stock, $.01 par value, authorized 10,000,000 shares; no
     shares issued and outstanding..................................          --            --
  Common stock, $.01 par value, authorized 100,000,000 shares;
     outstanding 38,570,544 and 38,570,544 shares; respectively.....         386           386
  Additional paid-in capital........................................     273,198       273,198
  Accumulated deficit...............................................     (89,232)           --
                                                                      ----------    ----------
                                                                         184,352       273,584
                                                                      ----------    ----------
                                                                      $1,676,523    $1,832,816
                                                                      ----------    ----------
                                                                      ----------    ----------
</TABLE>
 
         (See accompanying notes to consolidated financial statements)
 (The consolidated balance sheets reflect the reorganization described in Note
                                      1.)
 
                                      F-23
<PAGE>   102
 
                                   MESA INC.
 
                     CONSOLIDATED STATEMENTS OF CASH FLOWS
                            YEARS ENDED DECEMBER 31
                                 (IN THOUSANDS)
 
<TABLE>
<CAPTION>
                                                            1992          1991          1990
                                                          ---------     ---------     ---------
<S>                                                       <C>           <C>           <C>
CASH FLOWS FROM OPERATING ACTIVITIES:
  Net loss..............................................  $ (89,232)    $ (79,163)    $(200,276)
  Depreciation, depletion and amortization..............    113,933       117,076       163,781
  Securities (gains) losses.............................     (7,808)        2,060           452
  (Gains) losses on dispositions of oil and gas
     properties.........................................    (12,250)      (33,749)       81,029
  Increase in gas balancing receivables.................    (17,772)      (15,520)       (4,376)
  Decrease in deferred natural gas revenue..............    (10,287)       (5,296)       (6,392)
  Minority interest in loss.............................     (3,854)       (3,419)       (8,649)
  (Increase) decrease in accounts receivable............       (585)       18,611        (3,784)
  Increase (decrease) in payables and accrued
     liabilities........................................     (7,814)       11,909       (19,414)
  Other.................................................      7,230        22,469        11,445
                                                          ---------     ---------     ---------
          Cash provided by (used in) operating
            activities..................................    (28,439)       34,978        13,816
                                                          ---------     ---------     ---------
CASH FLOWS FROM INVESTING ACTIVITIES:
  Capital expenditures and acquisitions.................    (69,201)      (31,864)      (36,513)
  Proceeds from dispositions of oil and gas
     properties.........................................     11,424       428,063        40,098
  Sales of marketable securities........................    126,217       164,071       574,849
  Purchases of marketable securities....................   (102,161)     (132,051)     (367,583)
  Collection of notes receivable........................     28,181           224            56
  Other.................................................    (11,494)      (28,764)      (18,257)
                                                          ---------     ---------     ---------
          Cash provided by (used in) investing
            activities..................................    (17,034)      399,679       192,650
                                                          ---------     ---------     ---------
CASH FLOWS FROM FINANCING ACTIVITIES:
  Cash distributions to equity owners...................         --            --       (97,190)
  Long-term borrowings..................................         --       716,550       210,000
  Repayments of long-term debt..........................    (24,550)     (927,585)     (319,750)
  Funding of restricted cash balance....................         --       (66,061)           --
  Debt issuance costs...................................         --       (15,621)           --
  Other.................................................     (4,935)      (17,589)         (102)
                                                          ---------     ---------     ---------
          Cash used in financing activities.............    (29,485)     (310,306)     (207,042)
                                                          ---------     ---------     ---------
NET INCREASE (DECREASE) IN CASH AND CASH INVESTMENTS....    (74,958)      124,351          (576)
CASH AND CASH INVESTMENTS AT BEGINNING OF YEAR..........    232,155       107,804       108,380
                                                          ---------     ---------     ---------
CASH AND CASH INVESTMENTS AT END OF YEAR................  $ 157,197     $ 232,155     $ 107,804
                                                          ---------     ---------     ---------
                                                          ---------     ---------     ---------
</TABLE>
 
         (See accompanying notes to consolidated financial statements)
(The consolidated statements of cash flows reflect the reorganization described
                                  in Note 1.)
 
                                      F-24
<PAGE>   103
 
                                   MESA INC.
 
           CONSOLIDATED STATEMENTS OF CHANGES IN STOCKHOLDERS' EQUITY
                                 (IN THOUSANDS)
 
<TABLE>
<CAPTION>
                                                        COMMON STOCK      ADDITIONAL
                                                      ----------------     PAID-IN      ACCUMULATED
                                                      SHARES    AMOUNT     CAPITAL        DEFICIT
                                                      ------    ------    ----------    -----------
<S>                                                   <C>       <C>       <C>           <C>
Balance, December 31, 1989..........................  38,571     $386     $  585,355     $      --
  Net loss..........................................      --       --       (200,276)           --
  Distributions.....................................      --       --        (32,718)           --
                                                      ------    ------    ----------    -----------
Balance, December 31, 1990..........................  38,571      386        352,361            --
  Net loss..........................................      --       --        (79,163)           --
                                                      ------    ------    ----------    -----------
Balance, December 31, 1991..........................  38,571      386        273,198            --
  Net loss..........................................      --       --             --       (89,232)
                                                      ------    ------    ----------    -----------
Balance, December 31, 1992..........................  38,571     $386     $  273,198     $ (89,232)
                                                      ------    ------    ----------    -----------
                                                      ------    ------    ----------    -----------
</TABLE>
 
         (See accompanying notes to consolidated financial statements)
        (The consolidated statements of changes in stockholders' equity
                reflect the reorganization described in Note 1.)
 
                                      F-25
<PAGE>   104
 
                                   MESA INC.
 
                   NOTES TO CONSOLIDATED FINANCIAL STATEMENTS
 
(1) ORGANIZATION AND SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES
 
     MESA Inc., a Texas corporation, was formed in connection with a transaction
(the Corporate Conversion) which reorganized the business of Mesa Limited
Partnership (the Partnership). The Partnership was formed in 1985 to succeed to
the business of Mesa Petroleum Co. (Original Mesa). The Partnership was owned
98% by its limited partners and 2% by its general partner (the General Partner).
Unless the context otherwise requires, as used herein the term "Company" refers
to MESA Inc. and its subsidiaries taken as a whole and includes its
predecessors.
 
     Pursuant to the Corporate Conversion, the Partnership transferred
substantially all its assets and liabilities to the Company on December 31, 1991
in exchange for all outstanding shares of the Company's common stock. The common
units and general partner interests in the Partnership that were held by the
General Partner (which would otherwise have been converted into 4.14% of the
Company's common stock) were converted into a 4.14% general partner interest in
each direct subsidiary partnership of the Company. The Partnership allocated 1.0
share of the Company's common stock for each common unit and 1.35 shares of the
Company's common stock for each preference unit to its unitholders (other than
the General Partner). Concurrently, the Company effected a one-for-five reverse
split of the common stock and the Partnership distributed to its former
unitholders (other than the General Partner) .2 shares of common stock for each
common unit and .27 shares of common stock for each preference unit.
 
PRINCIPLES OF CONSOLIDATION
 
     The Company owns and operates its oil and gas properties and other assets
through subsidiary partnerships. The General Partner owns a 4.14% interest in
the direct subsidiary partnerships. The accompanying consolidated financial
statements reflect the consolidated accounts of the Company and the subsidiary
partnerships after elimination of intercompany transactions. The General
Partner's interest is reflected as a minority interest.
 
     The Corporate Conversion has been reflected in the consolidated accounts of
the Company as a reorganization of entities under common control whereby the
historical bases of the assets and liabilities of the Partnership have been
carried forward as the recorded bases for the Company. The accompanying
consolidated financial statements reflect a retroactive restatement for all
periods presented to reflect the Corporate Conversion.
 
     Certain reclassifications have been made to amounts reported in previous
years to conform to 1992 presentation.
 
STATEMENTS OF CASH FLOWS
 
     For purposes of the statements of cash flows, the Company classifies all
cash investments with original maturities of three months or less as cash and
cash investments.
 
INVESTMENTS
 
     Investments in marketable securities are stated at the lower of cost or
market value and are classified as current or noncurrent, depending on
management's intent at the balance sheet date. Periodic changes in the stated
value of the marketable securities portfolios are reflected in income in the
case of current investments and in stockholders' equity in the case of
noncurrent investments. The cost of securities sold is determined on the
first-in, first-out basis. The Company also enters into various futures
contracts which are not accounted for as hedges of existing assets and are
periodically adjusted to market price. Gains and losses from such contracts are
included in securities gains (losses).
 
                                      F-26
<PAGE>   105
 
                                   MESA INC.
 
           NOTES TO CONSOLIDATED FINANCIAL STATEMENTS -- (CONTINUED)
 
OIL AND GAS PROPERTIES
 
     Under the successful efforts method of accounting, all costs of acquiring
unproved oil and gas properties and drilling and equipping exploratory wells are
capitalized pending determination of whether the properties have proved
reserves. If an exploratory well is determined to be nonproductive, the drilling
and equipment costs of the well are expensed at that time. All development
drilling and equipment costs are capitalized. Capitalized costs of proved
properties and estimated future dismantlement and abandonment costs are
amortized on a property-by-property basis using the unit-of-production method.
Geological and geophysical costs and delay rentals are expensed as incurred.
 
     Unproved properties are periodically assessed for impairment of value and a
loss is recognized at the time of impairment. The aggregate carrying value of
proved properties is periodically compared with the undiscounted future net cash
flows from proved reserves, determined in accordance with Securities and
Exchange Commission (SEC) regulations, and a loss is recognized if permanent
impairment of value is determined to exist. A loss is recognized on proved
properties expected to be sold in the event that carrying value exceeds expected
sales proceeds.
 
LOSS PER SHARE
 
     The computations of loss per share are based on the weighted average number
of common shares outstanding during each period.
 
FAIR VALUE OF FINANCIAL INSTRUMENTS
 
     The Company's financial instruments consist of cash, marketable securities,
short-term trade receivables and payables, notes receivable, restricted cash and
long-term debt. The carrying values of cash, marketable securities, short-term
trade receivables and payables and restricted cash approximate fair value. It is
not practicable to estimate the fair value of a $27 million note receivable from
Bicoastal Corporation (Bicoastal) since Bicoastal is emerging from bankruptcy
and the Company's allowed claims in the bankruptcy exceed the carrying value of
the note. The Company expects to ultimately collect the recorded amount of the
note but the timing of collection is uncertain. See Note 8 for additional
discussion of the Bicoastal note. The fair value of long-term debt is estimated
based on the quoted market prices for the Company's publicly traded subordinated
debt and on current rates available for similar debt with similar maturities and
security for the Company's remaining debt.
 
GAS REVENUES
 
     The Company recognizes its ownership interest in natural gas sales as
revenue. Actual production quantities sold by the Company may be different than
its ownership share of production in a given period. If the Company's sales
exceed its ownership interest, the differences are recorded as deferred revenue.
Gas balancing receivables are recorded when the Company's ownership interest
exceeds sales. The Company also records production expenses related to its
ownership share of production. At December 31, 1992, the Company had produced a
net 10.5 billion cubic feet of natural gas less than its ownership interest and
had recorded gas balancing receivables, net of deferred revenues, of
approximately $19.2 million.
 
     The Company periodically enters into natural gas futures contracts as a
hedge against natural gas price fluctuations. Gains or losses on such hedges are
deferred and recognized as natural gas revenue when the hedged production
occurs. The Company recognized a loss of $1.0 million in 1990 related to hedging
activities and gains of $8.3 million and $5.6 million in 1991 and 1992,
respectively. These gains or losses are included in natural gas revenues for the
respective periods. As of December 31, 1992, the Company had deferred realized
losses of $.3 million which will be recognized as reductions of natural gas
revenue in the first quarter of 1993.
 
                                      F-27
<PAGE>   106
 
                                   MESA INC.
 
           NOTES TO CONSOLIDATED FINANCIAL STATEMENTS -- (CONTINUED)
 
TAXES
 
     The Company provides for income taxes using the asset and liability method
under which deferred income taxes are recognized for the tax consequences of
"temporary differences" by applying enacted statutory tax rates applicable to
future years to differences between the financial statement carrying amounts and
the tax bases of existing assets and liabilities. The effect on deferred taxes
of a change in tax laws or tax rates is recognized in income in the period that
includes the enactment date.
 
(2) RESOURCES AND LIQUIDITY
 
     Cash flows from operating activities for the years ended December 31, 1992,
1991 and 1990 were $(28) million, $35 million and $14 million, respectively. In
those same years, respectively, capital expenditures totaled $69 million, $32
million and $37 million, and cash used in financing activities, primarily to
repay or refinance debt, totaled $29 million, $310 million and $207 million. The
Company used proceeds from sales of oil and gas properties, proceeds from
collection of long-term receivables and cash and securities on hand to fund
obligations in excess of cash flows from operating activities.
 
     At December 31, 1992, the Company's long-term debt totaled $1.2 billion
(see Note 4). The Company also had $103 million of working capital; cash and
securities totaled $169 million. Of the $169 million of cash and securities, $64
million is held in Hugoton Capital Limited Partnership, an indirect subsidiary
partnership. The assets of this subsidiary partnership, which also holds
substantially all of the Company's Hugoton field natural gas properties and $581
million of secured debt, are dedicated to service the debt of this subsidiary
partnership and are not available to pay creditors of the Company or its other
subsidiaries.
 
     During 1993, the Company expects its interest requirements to total $139
million, its capital expenditures to total $36 million and its principal
payments on long-term debt to total $45 million (subject to matters described
below with respect to the revolving credit agreement [Credit Agreement]). The
Company's cash flows from sales of oil and gas production in 1993 are not
expected to be sufficient to service debt and fund capital expenditures.
 
     The Company's independent public accountants included an explanatory
paragraph in their report on the 1992 consolidated financial statements of the
Company which described a potential debt covenant default which raised
substantial doubt about the Company's ability to continue as a going concern.
See Note 14 for a discussion of recent events affecting the independent public
accountants' report. The consolidated financial statements of the Company have
been prepared assuming the Company will continue as a going concern.
Accordingly, no adjustments have been made to the consolidated financial
statements to reflect any possible liquidation of assets which may be required
in the event of bankruptcy. Management believes that the Company has several
alternatives to improve its cash flow and available cash, including the Exchange
Offer. The following discussion outlines Mesa's contingencies and alternatives.
 
POTENTIAL LONG-TERM DEBT DEFAULT
 
     The Company's financial forecasts indicate that, in the second or third
quarter of 1993, the Company's tangible adjusted equity, as defined, may fall
below the level required by a covenant contained in the Credit Agreement.
Borrowings under the Credit Agreement totaled $100 million at December 31, 1992
and, absent an acceleration, are due June 3, 1994. The Credit Agreement also
supports $10.6 million of outstanding letters of credit. See Note 4 for a
discussion of the Credit Agreement and tangible adjusted equity covenant. If the
Company were to fail to maintain the required level of tangible adjusted equity
and were unable to obtain a waiver of or renegotiate such covenant, it would be
in default under the Credit Agreement, giving the banks the right, subject to a
30-day grace period, to accelerate the principal payment of debt thereunder and
to require cash collateralization of outstanding letters of credit. The
Company's financial forecasts also indicate that available cash would be
insufficient to repay the amounts outstanding under the Credit Agreement in the
 
                                      F-28
<PAGE>   107
 
                                   MESA INC.
 
           NOTES TO CONSOLIDATED FINANCIAL STATEMENTS -- (CONTINUED)
 
event of default. Such an event of default, if not cured, would also constitute
an event of default under each of the indentures governing the Company's $600
million of subordinated notes, giving the holders of such notes the right to
accelerate such debt.
 
DEBT RESTRUCTURING
 
     The Company has proposed an exchange offer (Exchange Offer) whereby a new
series of 12% unsecured discount notes due in August 1998 would be offered to
existing holders of the Company's 12% and 13 1/2% subordinated notes. The new
notes would accrue, but not pay, interest through August 1, 1996, after which
interest would be payable in cash. If consummated, the Exchange Offer could
result in cash savings by deferring up to $77 million of interest payments per
year. See Note 4 for a description of the Exchange Offer. Management believes
that consummation of the Exchange Offer may facilitate its ability to obtain a
waiver of or to renegotiate the tangible adjusted equity covenant and, in
addition, to negotiate an extension of the final maturity date of the Credit
Agreement beyond June 1994. However, the Company has not yet sought any such
waiver or extension and no assurance can be given that, if the Exchange Offer is
completed, such changes will actually be achieved. The Company believes that
completion of the Exchange Offer may also increase the Company's ability to
obtain traditional equity or debt financing in the future to repay or refinance
its indebtedness. The Exchange Offer is intended to reduce the Company's cash
interest requirements through August 1996, which should enhance the Company's
ability to service its debt obligations and make capital expenditures from
available cash and operating cash flows. The Company is engaged in discussions
with financial and legal advisors representing a committee of its noteholders
regarding terms of the Exchange Offer. There can be no assurance that the
Exchange Offer will be made or consummated or, if consummated, what the level of
exchange will be. In addition, depending on industry conditions, the Company may
generate or preserve cash by seeking to amend the maturity of the Credit
Agreement, selling assets, issuing new debt or equity, reducing capital
expenditures, paying interest on the 12% subordinated notes with common stock,
seeking to otherwise defer payment of interest or pursuing other alternatives.
See Note 14 for a discussion of recent events relating to the Exchange Offer.
 
LITIGATION
 
     The Company is subject to various lawsuits, the most significant of which
relates to a 1985 investment in Unocal Corporation (Unocal). A trial is expected
later in 1993. As described in Note 9, a significant judgment against the
Company in the Unocal lawsuit would have a material adverse effect on the
financial position and results of operations of the Company. Payment of such a
judgment would remove a substantial amount of cash from the Company at a time
when cash flows from operating activities are not expected to be sufficient to
service debt and fund capital expenditures and other obligations. Such a payment
would also reduce tangible adjusted equity below $150 million. In the event of
an adverse judgment, the Company would expect to appeal but could be required to
post a bond or other security in the amount of the judgment in order to stay
execution pending appeal.
 
     In the event of an adverse decision, the Company could pursue a variety of
options including sales of assets, settlement discussions to reduce the amount
of the award or to limit bond requests or negotiations to obtain relief from
certain debt obligations to banks or subordinated noteholders. The Company could
also consider seeking protection from creditors under the Federal Bankruptcy
Code. The Company's choice of alternatives would depend on numerous factors
including the amount of the judgment, the status of the Exchange Offer, the
status of renegotiations of the Credit Agreement, and conditions in the oil and
gas industry.
 
                                      F-29
<PAGE>   108
 
                                   MESA INC.
 
           NOTES TO CONSOLIDATED FINANCIAL STATEMENTS -- (CONTINUED)
 
(3) MARKETABLE SECURITIES
 
     Marketable securities are as follows at December 31 (in thousands):
 
<TABLE>
<CAPTION>
                                                                    1992        1991
                                                                   -------     -------
        <S>                                                        <C>         <C>
        Cost.....................................................  $12,167     $28,183
        Unrealized gain (loss)...................................     (249)      2,698
                                                                   -------     -------
        Market value.............................................  $11,918     $30,881
                                                                   -------     -------
                                                                   -------     -------
</TABLE>
 
     During the year ended December 31, 1992, the Company recognized a net gain
of $7.8 million from its investments in securities and futures contracts
compared with net losses in 1991 and 1990 of $2.1 million and $.5 million,
respectively. The securities gains and losses do not include gains or losses
from natural gas futures contracts accounted for as hedges of natural gas
production. Hedge gains or losses are included in natural gas revenue in the
month in which the hedged production occurs. (See Note 1).
 
     The net gains and losses recognized during a period include both realized
and unrealized gains and losses. During 1992, the Company realized a net gain of
$10.0 million from securities transactions and futures contracts. Net realized
losses totaled $7.8 million and $11.6 million in 1991 and 1990, respectively.
 
(4) LONG-TERM DEBT
 
     Long-term debt and current maturities are as follows at December 31 (in
thousands):
 
<TABLE>
<CAPTION>
                                                                 1992           1991
                                                              ----------     ----------
        <S>                                                   <C>            <C>
        HCLP Secured Notes..................................  $  580,850     $  605,400
        Credit Agreement....................................     100,000        100,000
        12% subordinated notes..............................     300,000        300,000
        13 1/2% subordinated notes..........................     300,000        300,000
        Other...............................................       5,305          5,305
                                                              ----------     ----------
                                                               1,286,155      1,310,705
        Current maturities..................................     (44,555)        (6,310)
                                                              ----------     ----------
        Long-term debt......................................  $1,241,600     $1,304,395
                                                              ----------     ----------
                                                              ----------     ----------
</TABLE>
 
HCLP SECURED NOTES
 
     In 1991, Hugoton Capital Limited Partnership (HCLP), a subsidiary which
holds substantially all of the Company's Hugoton field natural gas properties,
issued $616 million of secured notes (HCLP Secured Notes) in a private placement
with a group of institutional lenders. The issuance replaced $550 million of
bank debt and funded a $66 million restricted cash balance within HCLP. The
restricted cash balance is available to supplement cash flows from the HCLP
properties in the event such cash flows are not sufficient to fund principal and
interest payments on the HCLP Secured Notes when due. As the HCLP Secured Notes
are repaid, the required restricted cash balance is reduced.
 
     The HCLP Secured Notes were issued in 15 series and have final stated
maturities extending through 2012 but can be retired earlier depending on the
rate of production from the Hugoton properties. As of December 31, 1992, $36
million has been repaid as scheduled. An additional $19.5 million of principal
was repaid as scheduled on March 1, 1993. The HCLP Secured Notes outstanding on
December 31, 1992, bear interest at fixed rates ranging from 8.6% to 11.3%
(weighted average 10.1%). Principal and interest payments are made semiannually.
Provisions in the HCLP Secured Note agreements require interest rate premiums to
be paid to the noteholders in the event that the HCLP Secured Notes are repaid
more rapidly or slowly than
 
                                      F-30
<PAGE>   109
 
                                   MESA INC.
 
           NOTES TO CONSOLIDATED FINANCIAL STATEMENTS -- (CONTINUED)
 
scheduled in the agreements. Such premiums, if required, would increase the
effective interest rate of the HCLP Secured Notes.
 
     The HCLP Secured Note agreements contain various covenants which, among
other things, limit HCLP's ability to sell or acquire oil and gas property
interests, incur additional indebtedness, make unscheduled capital expenditures,
make distributions of property or funds subject to the mortgage, or enter into
certain types of long-term contracts or forward sales of production. The
agreements also require HCLP to maintain separate existence from the Company.
The assets of HCLP are dedicated to service HCLP's debt and are not available to
pay creditors of the Company or its subsidiaries other than HCLP.
 
     Revenues received from production from HCLP's Hugoton properties are
deposited in a collection account maintained by a Collateral Agent. The
Collateral Agent releases or reserves funds, as appropriate, for the payment of
royalties, taxes, operating costs, capital expenditures and principal and
interest on the HCLP Secured Notes. Only after all required payments have been
made may any remaining funds held by the Collateral Agent be released from the
mortgage.
 
     In connection with the formation of HCLP and the issuance of the HCLP
Secured Notes, Mesa Operating Limited Partnership (MOLP), a Company subsidiary
and 81% owner of HCLP, entered into a services agreement with HCLP pursuant to
which MOLP will provide certain services necessary to operate the Hugoton field
properties and market production therefrom, process remittances of production
revenues and perform certain other administrative functions in exchange for a
services fee, which totaled approximately $11 million in 1992.
 
     The restricted cash balance and cash held by the Collateral Agent for
payment of interest and principal on the HCLP Secured Notes are invested by the
Collateral Agent under the terms of a guaranteed investment contract (GIC) with
Morgan Guaranty Trust Co. of New York (GIC Provider). The GIC Provider was paid
$13.9 million at the date of issuance of the HCLP Secured Notes to guarantee
that funds invested under the GIC would earn an interest rate equivalent to the
weighted average coupon rate on the outstanding principal balance of the HCLP
Secured Notes (10.1% at December 31, 1992). A portion of this amount may be
refunded if the HCLP Secured Notes are repaid earlier than if HCLP had produced
according to its scheduled production, depending primarily on prevailing
interest rates.
 
     In the first quarter of 1992, the Company contributed an additional $32
million in cash to HCLP which was not subject to the mortgage, a portion of
which was used to supplement HCLP's cash flows in order to make scheduled
principal payments in 1992. At December 31, 1992, approximately $17 million of
HCLP's cash was not subject to the mortgage and is expected to be used to
supplement HCLP's cash flow in 1993.
 
     HCLP's cash balances are as follows at December 31 (in thousands):
 
<TABLE>
<CAPTION>
                                                                    1992        1991
                                                                   -------     -------
        <S>                                                        <C>         <C>
        Cash included in current assets..........................  $64,141     $45,334
                                                                   -------     -------
                                                                   -------     -------
        Restricted cash included in noncurrent assets............  $64,339     $65,381
                                                                   -------     -------
                                                                   -------     -------
</TABLE>
 
CREDIT AGREEMENT
 
     The $150 million Credit Agreement, secured by the Company's West Panhandle
field oil and gas properties, is due in June 1994 and bears interest at a
designated prime rate or at a Eurodollar rate plus 1%. As of December 31, 1992,
the Company has borrowed $100 million under the Credit Agreement. The Credit
Agreement also supports $10.6 million of outstanding letters of credit. As a
result, and subject to certain conditions, $39.4 million of unused borrowing
capacity exists under the facility. The average interest rate under the Credit
Agreement at December 31, 1992 was 4.6%.
 
                                      F-31
<PAGE>   110
 
                                   MESA INC.
 
           NOTES TO CONSOLIDATED FINANCIAL STATEMENTS -- (CONTINUED)
 
     The Credit Agreement contains a covenant that requires the Company to
maintain tangible adjusted equity, as defined, of at least $150 million. At
December 31, 1992, tangible adjusted equity was $192 million. See Note 2 for a
discussion of possible acceleration of principal payments of the borrowings
under the Credit Agreement in the second or third quarter of 1993.
 
     The provisions of the Credit Agreement prohibit the Company from paying any
dividends to equity holders, other than those paid in the form of equity
securities.
 
     The Credit Agreement also contains a covenant that requires the Company to
maintain a ratio of cash flow and available cash to debt service, as each is
defined, of at least 1.25 to 1. At December 31, 1992, the ratio was 1.41 to 1.
 
SUBORDINATED NOTES
 
     The 12% subordinated notes are unsecured and mature in 1996. Interest on
these notes is payable quarterly and, at the option of the Company, may be paid
in common stock of the Company.
 
     The 13 1/2% subordinated notes are unsecured and mature in 1999. Interest
on these notes is payable semiannually in cash.
 
     The 13 1/2% subordinated notes contain a provision that restricts the
Company's ability to borrow additional funds (except for debt incurred to
refinance other debt and additional debt not exceeding $50 million) if it does
not maintain a defined cash flow coverage ratio. At December 31, 1992, the cash
flow coverage ratio was less than the requirement and, as a result, the Company
has limited ability to incur additional debt. The 12% and 13 1/2% subordinated
notes also restrict the ability of the Company to pay dividends to equity
holders if certain debt-to-equity ratios are not maintained. Under these
provisions, the Company is currently prohibited from paying dividends.
 
     Both subordinated note agreements also contain provisions which would
permit acceleration of the principal of the notes if the Company were in default
on other debt obligations including the Credit Agreement.
 
     On October 26, 1992, the Company filed a registration statement
(Registration Statement) with the SEC for a new series of 12% unsecured discount
notes (New Notes) due August 1998 to be offered in the Exchange Offer to
existing holders of the Company's 12% and 13 1/2% subordinated notes. As
proposed, the New Notes would accrue interest, but would not require cash
payments of interest, through August 1, 1996. The accreted value of the New
Notes, as defined, would increase from February 1, 1993 through August 1, 1996
at a rate of 12% per annum, compounded semiannually. After August 1, 1996, the
New Notes would accrue interest at 12% per annum, payable in cash. The New Notes
would be senior in right of payment to any 12% and 13 1/2% subordinated notes
that are not exchanged in the Exchange Offer.
 
     The Exchange Offer will be made only by means of a prospectus, after the
Registration Statement is declared effective by the SEC. The terms of the
Exchange Offer are currently being negotiated and there can be no assurance that
the Exchange Offer will be made or consummated.
 
INTEREST AND MATURITIES
 
     The aggregate interest payments during 1992, 1991 and 1990 were $142.7
million, $128.1 million, and $190.0 million, respectively.
 
                                      F-32
<PAGE>   111
 
                                   MESA INC.
 
           NOTES TO CONSOLIDATED FINANCIAL STATEMENTS -- (CONTINUED)
 
     The scheduled principal repayments on long-term debt for the next five
years are as follows:
 
<TABLE>
<CAPTION>
                                                   1993      1994     1995      1996     1997
                                                   -----    ------    -----    ------    -----
                                                                  (IN MILLIONS)
    <S>                                            <C>      <C>       <C>      <C>       <C>
    HCLP Secured Notes...........................  $39.3    $ 42.9    $39.3    $ 45.4    $46.7
    Credit Agreement*............................     --     100.0       --        --       --
    12% subordinated notes*......................     --        --       --     300.0       --
    Other........................................    5.3        --       --        --       --
                                                   -----    ------    -----    ------    -----
              Total..............................  $44.6    $142.9    $39.3    $345.4    $46.7
                                                   -----    ------    -----    ------    -----
                                                   -----    ------    -----    ------    -----
</TABLE>
 
- ---------------
 
*  See Note 2 for a discussion of possible acceleration of principal payments
   under the Credit Agreement and potential for cross defaults under the
   subordinated notes.
 
FAIR VALUE OF LONG-TERM DEBT
 
     Based on borrowing rates currently available for secured debt with similar
maturities and credit rating, the fair value of the HCLP Secured Notes at
December 31, 1992 is estimated to be approximately $630 million.
 
     Based on borrowing rates currently available for revolving bank loans with
similar collateral, the fair value of the Credit Agreement at December 31, 1992
is estimated to be its carrying value.
 
     The subordinated notes are publicly traded. Based on published trading
prices at December 31, 1992, the fair value of the 12% subordinated notes was
$243 million and the fair value of the 13 1/2% subordinated notes was $249
million.
 
     Based on the current financial condition of the Company, there is no
assurance that the Company could obtain borrowings under long-term debt
agreements with terms similar to those described above and receive proceeds
approximating the estimated fair values.
 
(5) INCOME TAXES
 
     At December 31, 1992, the tax basis of the Company's consolidated net
assets was greater than the financial basis of those net assets; therefore, no
deferred tax liability has been recorded. The primary difference between bases
for financial reporting purposes and for tax purposes is related to oil and gas
properties and results from (i) the additional basis recognized for tax purposes
when the Partnership was formed in 1985 and (ii) the tax basis adjustments
resulting from purchases and sales of Partnership units during the years 1986
through 1991.
 
     On February 10, 1992, the Financial Accounting Standards Board issued
Statement of Financial Accounting Standards (SFAS) No. 109, "Accounting for
Income Taxes," which the Company will adopt during the first quarter of 1993.
SFAS No. 109 provides for, among other things, the recognition of deferred tax
assets under certain circumstances. The tax basis of the Company's consolidated
net assets exceeds the financial basis at December 31, 1992. Therefore, the
Company will likely calculate a deferred tax asset upon adoption of SFAS No.
109. However, due to the Company's history of net operating losses and its
current financial condition, an offsetting valuation allowance will result in
little or no recognition of such asset. SFAS No. 109 prescribes an asset and
liability method to provide for income taxes. Other than allowing deferred tax
asset recognition, the provisions of SFAS No. 109 are similar to the Company's
current policy. As a result, the Company does not expect adoption of SFAS No.
109 to have a material effect on its financial position or results of
operations.
 
                                      F-33
<PAGE>   112
 
                                   MESA INC.
 
           NOTES TO CONSOLIDATED FINANCIAL STATEMENTS -- (CONTINUED)
 
     At December 31, 1992, the Company had a regular tax net operating loss
carryforward of approximately $135 million which will expire in 2007.
 
     The Company has assumed from the Partnership any tax liabilities or refunds
which may arise as a result of any changes to Original Mesa's taxable income or
loss for open tax years.
 
     The income tax returns of Original Mesa are open to examination by federal
and state taxing authorities for calendar years 1984 through 1987. The Internal
Revenue Service (IRS) has recently completed two field examinations of the open
tax years, which indicate that additional taxes for the subject periods may be
imposed. No formal tax assessment has been made by the IRS. An administrative
review of the field examinations is currently in process; therefore, the amount
of the eventual tax assessment, if any, cannot yet be determined. The Company
believes that it has adequately provided for any potential tax liability and
that the final resolution of the IRS examinations will not have a material
adverse effect on its financial position or results of operations.
 
     The tax returns of the Partnership for the years 1989 through 1991 are also
subject to examination by federal and state taxing authorities. If examinations
of the Partnership returns result in changes to taxable income or loss, the
taxable income or loss of the former partners and the tax basis of the Company's
assets will be changed accordingly.
 
(6) PROPERTY SALES
 
     In June 1992, the Company sold all of its Canadian interests (consisting of
overriding royalty interests in producing and nonproducing acreage) for
approximately $12 million in cash and recognized a $12 million gain.
 
     In April 1991, the Company sold its producing gas properties in the San
Juan Basin of New Mexico and Colorado for approximately $161 million in cash and
the assumption by the purchaser of approximately $2 million in liabilities
resulting in a gain of approximately $34 million.
 
     In March 1991, the Company sold certain of its producing oil and gas
properties and undeveloped leasehold acreage in the Texas Panhandle and in
Oklahoma for an aggregate of approximately $267 million in cash and the
assumption by the purchasers of approximately $7 million in liabilities. The
Company recognized a loss of $75 million in 1990 as a result of these
transactions.
 
(7) STOCKHOLDERS' EQUITY
 
     At December 31, 1992, the Company had outstanding 38.6 million shares of
common stock. The Company owns a 95.86% limited partnership interest in the
direct subsidiary partnerships and the General Partner owns a 4.14% interest.
The General Partner's interest is convertible into 1.7 million shares of common
stock.
 
     The Company also has authorized 10 million shares of preferred stock. No
shares of preferred stock have been issued as of December 31, 1992.
 
(8) NOTES RECEIVABLE
 
     Notes receivable consist primarily of claims against Bicoastal. A plan of
reorganization for Bicoastal has been approved by the Bankruptcy Court and the
Company collected approximately $28.1 million in 1992. At December 31, 1992, the
Company had recorded receivables totaling $27.2 million from Bicoastal. In the
confirmed bankruptcy plan, the Company has total remaining allowed claims of $40
million (net of the cash received in 1992). The Company expects that it will
ultimately collect at least the remaining recorded amount of $27.2 million, but
the timing of collection is uncertain. In addition to its allowed claims, the
Company may also collect certain interest amounts.
 
                                      F-34
<PAGE>   113
 
                                   MESA INC.
 
           NOTES TO CONSOLIDATED FINANCIAL STATEMENTS -- (CONTINUED)
 
(9) CONTINGENCIES
 
UNOCAL
 
     The Company is subject to a lawsuit relating to the investment in Unocal by
Original Mesa and certain other defendants (collectively, the Mesa Defendants).
This suit, filed in 1986 in Federal District Court in Los Angeles, alleges that,
pursuant to Section 16(b) of the Securities Exchange Act of 1934, "short-swing
profits" allegedly realized by the Mesa Defendants upon disposition of certain
shares of Unocal common stock in 1985 are recoverable by Unocal. In late 1992,
the Mesa Defendants made a motion for summary judgment that a 1985 settlement
agreement between the Mesa Defendants and Unocal released the Mesa Defendants
from any potential liability in the case. In March 1993, the court denied the
Mesa Defendants' motion and granted the plaintiffs' cross motion, holding that,
as a matter of law, the settlement agreement did not release the claim asserted
by Unocal in this lawsuit. As of March 12, 1993, the case was scheduled for
trial on June 8, 1993. The Company will have no liability in the case if it
prevails on either of the following grounds: (i) that the 1985 acquisition of
6.7 million shares of Unocal was, as the Company contends, effected in a single
purchase, or (ii) that the Mesa Defendants realized no profit on the disposition
of any Unocal shares that might be deemed subject to Section 16(b). See Note 14
for a discussion of recent events relating to the Unocal litigation.
 
     No determination can be made at this time as to the ultimate outcome of the
litigation. If the plaintiffs were to prevail and were awarded a judgment
(including interest) in the range of their estimate of $150 million, payment of
such amount would have a material adverse effect on the financial position and
results of operations of the Company. Consequences to the Company of an adverse
decision are discussed in Note 2.
 
MASTERSON
 
     In February 1992, the current lessors of an oil and gas lease (the Gas
Lease) dated April 30, 1955, between R.B. Masterson, et al., as lessor, and
Colorado Interstate Gas Company (CIG), as lessee, sued CIG in Federal District
Court in Amarillo, Texas, claiming that CIG had underpaid royalties due under
the Gas Lease. The Company owns an interest in the Gas Lease. The plaintiffs
alleged that the underpayment was the result of CIG's use of an improper gas
sales price upon which to calculate royalties, and that the proper price should
have been determined pursuant to a pricing clause in a July 1, 1967 amendment to
the Gas Lease. The complaint did not specify the damages sought and appeared to
relate only to royalties for periods after October 1, 1988. The plaintiffs also
sought a declaration by the court as to the proper price to be used for
calculating future royalties.
 
     In August 1992, CIG filed a third-party complaint against the Company for
any such royalty underpayments which may be allocable to the Company's Interest
in the Gas Lease.
 
     On December 22, 1992, the plaintiffs filed a Second Amended Complaint,
including both CIG and the Company as defendants, again alleging that the use of
an improper price in calculating royalties resulted in underpayments of royalty,
but for the first time alleging that the underpayments amounted to approximately
$250 million (including interest) and covered the period from July 1, 1967 to
the present. In addition, the plaintiffs seek exemplary damages.
 
     Management believes that the Company has several defenses to plaintiffs'
claims, including (i) that the royalties for all periods were properly computed
and paid and (ii) that plaintiffs' claims with respect to all periods prior to
October 1, 1988 (which appear to account for the substantial portion of the
above $250 million of claims) were explicitly released by a 1988 written
agreement among the plaintiffs, CIG and the Company and are further barred by
the statute of limitations. If the plaintiffs were to prevail, the manner in
which any resulting liability would be shared between the Company and CIG would
depend on the resolution of issues relating to the contractual agreements and
the relationship between the Company, CIG and the lessors during the period in
question.
 
                                      F-35
<PAGE>   114
 
                                   MESA INC.
 
           NOTES TO CONSOLIDATED FINANCIAL STATEMENTS -- (CONTINUED)
 
     No determination can be made at this time as to the ultimate outcome of the
litigation and no trial date has been set.
 
PREFERENCE UNITHOLDERS
 
     The Company is a defendant in lawsuits related to the Corporate Conversion
pending in the U.S. District Court for the Northern District of Texas-Dallas
Division. Plaintiffs allege, among other things, that (i) the proxy materials
delivered to unitholders in connection with the Corporate Conversion contained
material misstatements and omissions, (ii) the general partners of the
Partnership breached fiduciary duties to the preference unitholders in
structuring the transaction and allocating the common stock of the Company and
(iii) the Corporate Conversion was not properly approved by the unitholders of
the Partnership because certain procedural requirements of the partnership
agreement were allegedly not met. The Company and the other defendants have
denied the allegations and believe they are without merit. Plaintiffs seek an
order requiring payment to the former preference unitholders of $164 million in
respect of the preferential distribution rights of their units, a declaration
declaring the Corporate Conversion void and rescinding it, unspecified
compensatory and punitive damages and other relief.
 
OTHER
 
     The Company is also a defendant in other lawsuits and has assumed
liabilities relating to Original Mesa and the Partnership. The Company does not
expect the resolution of the Masterson and preference unitholder lawsuits or any
of these other matters to have a material adverse effect on its financial
position or results of operations.
 
(10) EMPLOYEE BENEFIT PLANS
 
     The Company maintains two defined contribution retirement plans for the
benefit of its employees. The Company expensed $3.3 million in 1992, $3.1
million in 1991, and $4.4 million in 1990 in connection with these plans.
 
     In December 1991, the stockholders of the Company approved the 1991 Stock
Option Plan of the Company (the Option Plan), which authorized the grant of
options to purchase up to 2 million shares of common stock to be granted to
officers and key employees. The exercise price of each share of common stock
placed under option pursuant to the Option Plan cannot be less than 100% of the
fair market value of such share of common stock on the date the option is
granted. Upon exercise, the grantee may elect to receive either shares of common
stock or, at the discretion of the Option Committee of the Board of Directors,
cash or certain combinations of stock and cash in an amount equal to the excess
of the fair market value of the common stock at the time of exercise over the
exercise price. At December 31, 1992, the following stock options were
outstanding:
 
<TABLE>
<CAPTION>
NUMBER OF      DATE OF     EXERCISE PRICE
 OPTIONS        GRANT        PER SHARE        EXERCISABLE
- ---------     ---------    --------------     -----------
<S>            <C>             <C>            <C>
1,186,000       1/10/92        $ 6.81           355,800
   10,000       5/19/92          4.13             3,000
  156,000      10/02/92         11.69                --
- ---------                                     -----------
1,352,000                                       358,800
- ---------                                     -----------
- ---------                                     -----------
</TABLE>
 
     Options are exercisable from date of grant as follows: after six months,
30%; after one year, 55%; after two years, 80%; and after three years, 100%. At
December 31, 1992, options for 638,000 shares were available for grant.
 
                                      F-36
<PAGE>   115
 
                                   MESA INC.
 
           NOTES TO CONSOLIDATED FINANCIAL STATEMENTS -- (CONTINUED)
 
     The Company had agreements with two officers to provide postretirement
deferred compensation at the rate of one-half of the participant's final rate of
compensation (subject to minimum amounts specified in the agreements) for a
period of 10 years following the date of retirement or death. In 1992, in order
to terminate the deferred compensation agreements, the Company established life
insurance plans, executed agreements with the two officers and purchased
insurance policies at an aggregate cost of $4.9 million. At the time they were
terminated, approximately $3.9 million had been accrued under the deferred
compensation agreements. The Company has fully funded the life insurance
policies and has no further obligations under such policies or under the
deferred compensation agreements.
 
     The Company provides postretirement medical benefits for its retired
employees and retired employees of Pioneer Corporation (acquired in 1986). In
December 1990, SFAS No. 106, "Employers' Accounting for Postretirement Benefits
Other Than Pensions," was issued requiring accrual basis accounting for such
benefits. As a result, the Company will be required to record a liability
related primarily to postretirement medical costs for retired and current
employees. The Company will adopt SFAS No. 106 in 1993. The liability for
benefits existing at the date of adoption will be amortized over 20 years. The
Company believes that the adoption of the new standard will not have a material
effect on its financial position or its results of operations.
 
(11) MAJOR CUSTOMERS
 
     Revenues include sales to Mapco Oil and Gas Company (Mapco) of $45.7
million (19.4%), Western Resources, Inc. (WRI) formerly Kansas Power & Light
Company, of $39.7 million (16.8%) and Energas Company of $23.7 million (10.0%)
in 1992. In 1991, revenues included sales to Mapco of $51.9 million (20.9%) and
WRI of $27.9 million (11.2%). In 1990, revenues included sales to Mapco of $52.0
million (16.2%) and WRI of $42.0 million (13.1%).
 
(12) CONCENTRATIONS OF CREDIT RISK
 
     Substantially all of the Company's accounts receivable at December 31, 1992
result from oil and gas sales and joint interest billings to third party
companies in the oil and gas industry. This concentration of customers and joint
interest owners may impact the Company's overall credit risk, either positively
or negatively, in that these entities may be similarly affected by changes in
economic or other conditions. In determining whether or not to require
collateral from a customer or joint interest owner, the Company analyzes the
entity's net worth, cash flows, earnings, and credit ratings. Receivables are
generally not collateralized. Historical credit losses incurred by the Company
on receivables have not been significant.
 
(13) CONDENSED CONSOLIDATING FINANCIAL STATEMENTS
 
     The Company conducts its operations through various direct and indirect
subsidiaries. Mesa Inc.'s direct subsidiaries are MOLP, Mesa Midcontinent
Limited Partnership (MMLP) and Mesa Holding Limited Partnership. MOLP owns all
of the Company's interest in the West Panhandle field of Texas, the Gulf Coast
and the Rocky Mountain area as well as an approximate 81% limited partnership
interest in HCLP. MMLP owns an approximate 19% limited partnership interest in
HCLP. HCLP owns substantially all of the Company's Hugoton field natural gas
properties and is liable for the HCLP Secured Notes (see Note 4). The assets and
cash flows of HCLP are dedicated to service the HCLP Secured Notes and are not
available to pay creditors of the Company or its subsidiaries other than HCLP.
MOLP and Mesa Inc. are liable for the Credit Agreement and the 12% and 13 1/2%
subordinated notes and will be liable for any new debt issued under the terms of
the Exchange Offer. Mesa Capital Corp. (Mesa Capital), a wholly owned subsidiary
of MOLP, is also an obligor under the 12% and 13 1/2% subordinated notes. Mesa
Capital is a financing subsidiary and has insignificant assets and results of
operations. Mesa Capital is included with MOLP in the condensed consolidating
financial statements.
 
                                      F-37
<PAGE>   116
 
                                   MESA INC.
 
           NOTES TO CONSOLIDATED FINANCIAL STATEMENTS -- (CONTINUED)
 
     The following are condensed consolidating financial statements of MESA
Inc., HCLP, MOLP and the Company's other direct and indirect subsidiaries
combined (in millions):
 
CONDENSED CONSOLIDATING BALANCE SHEETS
 
<TABLE>
<CAPTION>
                                                                  OTHER       CONSOLIDATION       THE
                                        MESA                     COMPANY           AND          COMPANY
          DECEMBER 31, 1992             INC.   HCLP    MOLP    SUBSIDIARIES    ELIMINATION    CONSOLIDATED
- --------------------------------------  ----   ----   ------   ------------   -------------   ------------
<S>                                     <C>    <C>    <C>        <C>            <C>             <C>
Assets:
  Cash and cash investments...........  $--    $64    $   16       $ 77           $  --          $  157
  Other current assets................   --     22        31          9              --              62
                                        ----   ----   ------     ------       -------------   ------------
     Total current assets.............   --     86        47         86              --             219
                                        ----   ----   ------     ------       -------------   ------------
  Property, plant and equipment,
     net..............................   --    682       598         --              --           1,280
  Investment in subsidiaries..........  193     --        51        191            (435)             --
  Intercompany receivables............   --     --       138         --            (138)             --
  Other assets........................   --     91        56         30              --             177
                                        ----   ----   ------     ------       -------------   ------------
                                        $193   $859   $  890       $307           $(573)         $1,676
                                        ----   ----   ------     ------       -------------   ------------
                                        ----   ----   ------     ------       -------------   ------------
Liabilities and Equity:
  Current liabilities.................  $--    $74    $   40       $  2           $  --          $  116
  Long-term debt......................   --    542       700         --              --           1,242
  Intercompany payables...............    9     --        --        142            (151)             --
  Other noncurrent liabilities........   --     --       113         13              --             126
  Minority interest...................   --     --        --         --               8               8
  Partners'/stockholders' equity......  184    243        37        150            (430)            184
                                        ----   ----   ------     ------       -------------   ------------
                                        $193   $859   $  890       $307           $(573)         $1,676
                                        ----   ----   ------     ------       -------------   ------------
                                        ----   ----   ------     ------       -------------   ------------
DECEMBER 31, 1991
Assets:
  Cash and cash investments...........  $--    $45    $  126       $ 61           $  --          $  232
  Other current assets................   --     24        25         28              --              77
                                        ----   ----   ------     ------       -------------   ------------
     Total current assets.............   --     69       151         89              --             309
                                        ----   ----   ------     ------       -------------   ------------
  Property, plant and equipment,
     net..............................   --    713       617         --              --           1,330
  Investment in subsidiaries..........  280     --        41        188            (509)             --
  Intercompany receivables............   --     --       160         --            (160)             --
  Other assets........................   --     93        45         55              --             193
                                        ----   ----   ------     ------       -------------   ------------
                                        $280   $875   $1,014       $332           $(669)         $1,832
                                        ----   ----   ------     ------       -------------   ------------
                                        ----   ----   ------     ------       -------------   ------------
Liabilities and Equity:
  Current liabilities.................  $ 3    $39    $   49       $  1           $  --          $   92
  Long-term debt......................   --    599       705         --              --           1,304
  Intercompany payables...............    3     --        --        156            (159)             --
  Other noncurrent liabilities........   --      6       130         14              --             150
  Minority interest...................   --     --        --         --              12              12
  Partners'/stockholders' equity......  274    231       130        161            (522)            274
                                        ----   ----   ------     ------       -------------   ------------
                                        $280   $875   $1,014       $332           $(669)         $1,832
                                        ----   ----   ------     ------       -------------   ------------
                                        ----   ----   ------     ------       -------------   ------------
</TABLE>
 
                                      F-38
<PAGE>   117
                                   MESA INC.
 
           NOTES TO CONSOLIDATED FINANCIAL STATEMENTS -- (CONTINUED)
 
CONDENSED CONSOLIDATING STATEMENTS OF OPERATIONS
 
YEAR ENDED:
<TABLE>
<CAPTION>
                                                                        OTHER       CONSOLIDATION       THE
                                              MESA                     COMPANY           AND          COMPANY
             DECEMBER 31, 1992                INC.    HCLP   MOLP    SUBSIDIARIES    ELIMINATION    CONSOLIDATED
- --------------------------------------------  -----   ----   -----   ------------   -------------   ------------
<S>                                           <C>     <C>    <C>        <C>             <C>            <C>
Revenues:...................................  $ --    $88    $149       $   --          $  --          $  237
                                              -----   ----   -----      ------         ------          ------
Costs and Expenses:
  Operating, exploration and taxes..........    --     22      51           --             --              73
  General and administrative................    --     --      24           --             --              24
  Depreciation, depletion and
    amortization............................    --     34      80           --             --             114
                                              -----   ----   -----      ------         ------          ------
                                                --     56     155           --             --             211
                                              -----   ----   -----      ------         ------          ------
Operating Income (Loss).....................    --     32      (6 )         --             --              26
                                              -----   ----   -----      ------         ------          ------
Interest Expense, net of Interest Income....    --    (52 )   (80 )          2             --            (130)
Intercompany Interest Income (Expense)......    --     --      18          (18)            --              --
Securities Gains (Losses)...................    --     --      (3 )         11             --               8
Gains on Dispositions of Oil and Gas
  Properties................................    --     --      12           --             --              12
Equity in Loss of Subsidiaries..............   (87 )   --     (16 )         (4)           107              --
Minority Interest...........................    --     --      --           --              4               4
Other.......................................    (2 )   --     (18 )         (2)            13              (9)
                                              -----   ----   -----      ------         ------          ------
Net Loss....................................  $(89 )  $(20)  $(93 )     $  (11)         $ 124          $  (89)
                                              -----   ----   -----      ------         ------          ------
                                              -----   ----   -----      ------         ------          ------
DECEMBER 31, 1991
Revenues:...................................  $ --    $57    $178       $   15          $  --          $  250
                                              -----   ----   -----      ------         ------          ------
Costs and Expenses:
  Operating, exploration and taxes..........    --     13      53            5             --              71
  General and administrative................    --     --      27            1             --              28
  Depreciation, depletion and
    amortization............................    --     25      81           11             --             117
                                              -----   ----   -----      ------         ------          ------
                                                --     38     161           17             --             216
                                              -----   ----   -----      ------         ------          ------
Operating Income (Loss).....................    --     19      17           (2)            --              34
                                              -----   ----   -----      ------         ------          ------
Interest Expense, net of Interest Income....    --    (30 )  (100 )         (4)            --            (134)
Intercompany Interest Income (Expense)......    --     --       8           (8)            --              --
Securities Gains (Losses)...................    --     --       8          (10)            --              (2)
Gains on Dispositions of Oil and Gas
  Properties................................    --     --      34           --             --              34
Equity in Loss of Subsidiaries..............   (73 )   --      (9 )         (2)            84              --
Minority Interest...........................    --     --      --           --              3               3
Other.......................................    (6 )   --     (23 )         15             --             (14)
                                              -----   ----   -----      ------         ------          ------
Net Loss....................................  $(79 )  $(11)  $(65 )     $  (11)         $  87          $  (79)
                                              -----   ----   -----      ------         ------          ------
                                              -----   ----   -----      ------         ------          ------
DECEMBER 31, 1990
Revenues:...................................  $ --    $--    $262       $   68          $  --          $  330
                                              -----   ----   -----      ------         ------          ------
Costs and Expenses:
  Operating, exploration and taxes..........    --     --      77           18             --              95
  General and administrative................    --     --      22            6             --              28
  Depreciation, depletion and
    amortization............................    --     --     113           51             --             164
                                              -----   ----   -----      ------         ------          ------
                                                --     --     212           75             --             287
                                              -----   ----   -----      ------         ------          ------
Operating Income (Loss).....................    --     --      50           (7)            --              43
                                              -----   ----   -----      ------         ------          ------
Interest Expense, net of Interest Income....    --     --    (147 )        (23)            --            (170)
Intercompany Interest Income (Expense)......    --     --      21          (21)            --              --
Securities Gains (Losses)...................    --     --      22          (22)            --              --
Gains (Losses) on Dispositions of Oil and
  Gas Properties............................    --     --       3          (89)             5             (81)
Equity in Loss of Subsidiaries..............  (200 )   --      --           --            200              --
Minority Interest...........................    --     --      --           --              9               9
Other.......................................    --     --     (28 )         27             --              (1)
                                              -----   ----   -----      ------         ------          ------
Net Loss....................................  $(200)  $--    $(79 )     $ (135)         $ 214          $ (200)
                                              -----   ----   -----      ------         ------          ------
                                              -----   ----   -----      ------         ------          ------
</TABLE>
                                      F-39
<PAGE>   118
                                   MESA INC.
 
           NOTES TO CONSOLIDATED FINANCIAL STATEMENTS -- (CONTINUED)
 
CONDENSED CONSOLIDATING STATEMENTS OF CASH FLOWS
 
YEAR ENDED:
<TABLE>
<CAPTION>
                                                                        OTHER       CONSOLIDATION       THE
                                              MESA                     COMPANY           AND          COMPANY
             DECEMBER 31, 1992                INC.   HCLP    MOLP    SUBSIDIARIES    ELIMINATION    CONSOLIDATED
- --------------------------------------------  ----   -----   -----   ------------   -------------   ------------
<S>                                           <C>    <C>     <C>     <C>            <C>             <C>
Cash Flows from Operating Activities........  $--    $ 16    $(44 )     $   --          $  --          $  (28)
                                              ----   -----   -----      ------         ------          ------
Cash Flows from Investing Activities:
  Capital expenditures......................   --      (3 )   (66 )         --             --             (69)
  Proceeds from sales of oil and gas
    properties..............................   --      --      11           --             --              11
  Securities transactions, net..............   --      --      (8 )         32             --              24
  Contributions to subsidiaries.............   --      --     (25 )         (7)            32              --
  Other.....................................   --      --      23           25            (31)             17
                                              ----   -----   -----      ------         ------          ------
                                               --      (3 )   (65 )         50              1             (17)
                                              ----   -----   -----      ------         ------          ------
Cash Flows from Financing Activities:
  Repayments of long-term debt..............   --     (25 )    --           --             --             (25)
  Contributions from equity holders.........   --      32      --           --            (32)             --
  Other.....................................   --      (1 )    (1 )        (34)            31              (5)
                                              ----   -----   -----      ------         ------          ------
                                               --       6      (1 )        (34)            (1)            (30)
                                              ----   -----   -----      ------         ------          ------
Net Increase (Decrease) in Cash and Cash
  Investments...............................  $--    $ 19    $(110)     $   16          $  --          $  (75)
                                              ----   -----   -----      ------         ------          ------
                                              ----   -----   -----      ------         ------          ------
DECEMBER 31, 1991
Cash Flows from Operating Activities........  $--    $ 28    $  8       $   (1)         $  --          $   35
                                              ----   -----   -----      ------         ------          ------
Cash Flows from Investing Activities:
  Capital expenditures......................   --      (2 )   (29 )         (1)            --             (32)
  Proceeds from sales of oil and gas
    properties..............................   --      --     313          115             --             428
  Securities transactions, net..............   --      --       6           26             --              32
  Contributions to subsidiaries.............   --      --     (28 )         --             28              --
  Other.....................................   --      --     (17 )        (13)             1             (29)
                                              ----   -----   -----      ------         ------          ------
                                               --      (2 )   245          127             29             399
                                              ----   -----   -----      ------         ------          ------
Cash Flows from Financing Activities:
  Long-term borrowings......................   --     617     100           --             --             717
  Repayments of long-term debt..............   --    (562 )  (246 )       (120)            --            (928)
  Contributions from equity holders.........   --      28      --           --            (28)             --
  Other.....................................   --     (64 )   (29 )         (5)            (1)            (99)
                                              ----   -----   -----      ------         ------          ------
                                               --      19    (175 )       (125)           (29)           (310)
                                              ----   -----   -----      ------         ------          ------
Net Increase (Decrease) in Cash and Cash
  Investments...............................  $--    $ 45    $ 78       $    1          $  --          $  124
                                              ----   -----   -----      ------         ------          ------
                                              ----   -----   -----      ------         ------          ------
DECEMBER 31, 1990
Cash Flows from Operating Activities........  $--    $ --    $ (2 )     $   16          $  --          $   14
                                              ----   -----   -----      ------         ------          ------
Cash Flows from Investing Activities:
  Capital expenditures......................   --      --     (25 )        (11)            --             (36)
  Proceeds from sales of oil and gas
    properties..............................   --      --      31            9             --              40
  Securities transactions, net..............   --      --      19          188             --             207
  Distribution from subsidiaries............   97      --      --           --            (97)             --
  Other.....................................   --      --      58           (4)           (72)            (18)
                                              ----   -----   -----      ------         ------          ------
                                               97      --      83          182           (169)            193
                                              ----   -----   -----      ------         ------          ------
Cash Flows from Financing Activities:
  Long-term borrowings......................   --      --     210           --             --             210
  Repayments of long-term debt..............   --      --    (208 )       (112)            --            (320)
  Distributions to equity holders...........  (97 )    --     (97 )         --             97             (97)
  Other.....................................   --      --      --          (72)            72              --
                                              ----   -----   -----      ------         ------          ------
                                              (97 )    --     (95 )       (184)           169            (207)
                                              ----   -----   -----      ------         ------          ------
Net Increase (Decrease) in Cash and Cash
  Investments...............................  $--    $ --    $(14 )     $   14          $  --          $   --
                                              ----   -----   -----      ------         ------          ------
                                              ----   -----   -----      ------         ------          ------
</TABLE>
                                      F-40
<PAGE>   119
 
                                   MESA INC.
 
           NOTES TO CONSOLIDATED FINANCIAL STATEMENTS -- (CONTINUED)
 
NOTES TO CONDENSED CONSOLIDATING FINANCIAL STATEMENTS
 
(a) These condensed consolidating financial statements should be read in
    conjunction with the consolidated financial statements and notes thereto of
    the Company of which this note is an integral part.
 
(b) MESA Inc. owns a 95.86% limited partnership interest in each of MOLP, MMLP
    and MHLP. The General Partner owns 4.14% of each of these subsidiary
    partnerships. These condensed consolidating financial statements present
    MESA Inc.'s investment in its subsidiaries and MOLP's and MMLP's investments
    in HCLP using the equity method. Under this method, investments are recorded
    at cost and adjusted for the parent company's ownership share of the
    subsidiary's cumulative results of operations. In addition, investments
    increase in the amount of contributions to subsidiaries and decrease in the
    amount of distributions from subsidiaries.
 
(c) The consolidating financial statements include the results of operations and
    cash flows of HCLP as a separate entity after June 12, 1991 (the date of
    inception of HCLP). Prior to June 1991, MOLP and MMLP owned the Hugoton
    field natural gas properties currently owned by HCLP. As a result, results
    of operations and cash flows related to the Hugoton field properties are
    included with the results of operations and cash flows of MOLP and MMLP
    (included in other Company subsidiaries) for the first five months of 1991
    and for all of 1990.
 
(d) In connection with the formation of HCLP, MOLP and MMLP contributed
    producing natural gas properties in the Hugoton field and long-term debt to
    HCLP in return for limited partnership interests. These transactions did not
    require cash and are not reflected in the statements of cash flows of HCLP,
    MOLP or MMLP.
 
          Non-cash contributions by MOLP and MMLP from inception (June 12, 1991)
     to December 31, 1992 are summarized below (in thousands):
 
<TABLE>
<CAPTION>
                                                              MOLP          MMLP
                                                            ---------     --------
            <S>                                             <C>           <C>
            Oil and gas properties........................  $ 447,501     $288,819
            Long-term debt................................   (451,283)     (99,206)
            Other assets, net of liabilities..............     26,080        1,365
            General Partner...............................       (113)        (964)
                                                            ---------     --------
                                                            $  22,185     $190,014
                                                            ---------     --------
                                                            ---------     --------
</TABLE>
 
(e) The consolidation and elimination entries (i) eliminate the equity method
    investment in subsidiaries and equity in loss of subsidiaries, (ii)
    eliminate the intercompany payables and receivables, (iii) eliminate other
    transactions between subsidiaries including contributions and distributions
    and (iv) establish the General Partner's minority interest in the
    consolidated results of operations and financial position of the Company.
 
(14) SUBSEQUENT EVENTS
 
  Completion of the Exchange Offer
 
     In August 1993, the Company completed the Exchange Offer and effected
certain amendments to the Credit Agreement. The Exchange Offer and related
amendments to the Credit Agreement are more fully described in Notes 2 and 4 to
the consolidated financial statements of the Company for the nine months ended
September 30, 1993 included elsewhere in this Prospectus.
 
     Completion of the Exchange Offer results in the deferral of approximately
$75 million of annual interest payments which would have been paid through June
1995. As a result of the completion of the Exchange Offer and the related
amendments to the Credit Agreement, the Company expects to be able to service
its debt and make capital expenditures with cash flows generated by operating
activities and with existing cash and securities balances during the next two
years. On December 31, 1995, the Company will begin making
 
                                      F-41
<PAGE>   120
 
                                   MESA INC.
 
           NOTES TO CONSOLIDATED FINANCIAL STATEMENTS -- (CONTINUED)
 
interest payments on the 12 3/4% secured discount notes due June 30, 1998 and
the 12 3/4% discount notes due June 30, 1996 (together, the Discount Notes)
issued in the Exchange Offer. Assuming no changes in the Company's capital
structure prior to such date, the Company will be required to make cash interest
payments related to the Discount Notes totaling approximately $48 million
(approximately $51 million if the additional secured discount notes offered by
this Prospectus are issued) on December 31, 1995 and payments totaling
approximately $84 million (approximately $90 million if such additional secured
discount notes are issued) during 1996. In addition, 12 3/4% unsecured discount
notes in the amount of $178.8 million and 12% subordinated notes in the amount
of $6.3 million become due in mid-1996. The Company's current financial
forecasts indicate that the Company will be unable to fund such payments in 1996
with cash flows from operating activities and existing cash and securities
balances. Depending on industry and market conditions, the Company may generate
cash by selling assets or issuing new debt or equity securities. However, the
Company has limited ability to sell assets since its two largest assets, its
interests in the Hugoton and West Panhandle fields, are pledged under long-term
debt agreements. After the June 30, 1995 repayment of the balances outstanding
under the Credit Agreement, the Company would have $82.5 million of first lien
borrowing capacity on the West Panhandle field properties. The Company's current
business strategy includes continuing its efforts to strengthen its financial
condition by raising equity capital and applying the proceeds thereof to retire
debt, and issuing new lower-cost debt to refinance its existing high cost debt
securities. There can be no assurance that the Company will be able to raise
equity capital or otherwise refinance its debt.
 
     As described in Note 2 to the consolidated financial statements, the
Company's independent public accountants had previously included an explanatory
paragraph in their report on the 1992 consolidated financial statements of the
Company which described a potential debt covenant default which raised
substantial doubt about the Company's ability to continue as a going concern. In
conjunction with the filing of this Prospectus, the Company's independent public
accountants reissued their report on the Company's 1992 consolidated financial
statements. As a result of the successful completion of the Exchange Offer and
the related amendments to the Credit Agreement, the explanatory paragraph was
not included in the reissued independent public accountants' report.
 
     However, as a result of the potential adverse financial consequences
discussed above relating to certain principal and interest payments due in 1996
on the Company's debt, the Company's independent public accountants' report, as
reissued for this Prospectus, contains an "emphasis-of-a-matter" paragraph which
calls attention to such matters.
 
  Unocal Settlement
 
     On January 11, 1994, the Company entered into a settlement agreement with
respect to the Unocal lawsuit described in Note 8 above, whereby the Company and
the other defendants have agreed to pay to Unocal an aggregate of $47.5 million,
of which $42.75 million will be paid by the Company and $4.75 million will be
paid by certain other unaffiliated third parties. The settlement agreement is
subject to approval by the Court, following notice by Unocal to its security
holders. The Company intends to fund substantially all of its portion of the
settlement amount with proceeds from issuance of additional 12 3/4% secured
discount notes. If the settlement agreement is not approved by the Court, the
agreement will terminate and the parties will jointly request the Court to set
the earliest practicable trial date. The Company expects to accrue a loss in the
amount of its share of the settlement in the fourth quarter of 1993.
 
  Other Events.
 
     See Note 10 to the Company's consolidated financial statements for the nine
months ended September 30, 1993, included elsewhere in this Prospectus, for a
discussion of other recent events relating to the Company's subsidiary
partnerships, the General Partner's interest and the IRS examinations relating
to the 1984 through 1987 tax years.
 
                                      F-42
<PAGE>   121
 
                                   MESA INC.
 
                          SUPPLEMENTAL FINANCIAL DATA
 
OIL AND GAS RESERVES AND COST INFORMATION (UNAUDITED) --
 
     Net proved oil and gas reserves as of December 31, 1992 associated with the
Company's two most significant natural gas producing fields were estimated by
DeGolyer and MacNaughton, independent petroleum engineering consultants (D&M).
These two fields, the Hugoton and West Panhandle fields, represent over 95% of
the Company's net proved equivalent natural gas reserves at December 31, 1992.
The Company's remaining reserves in the Rocky Mountain, Gulf Coast and deep
Hugoton regions were estimated by Company engineers. All of the Company's
reserves at December 31, 1992 were in the United States. Net proved oil and gas
reserves in the Untied States and Canada as of December 31, 1991 and 1990 were
estimated by D&M. The reserves in Canada were less than 2% of the total
equivalent reserves of the Company and are not presented separately in this
report. The Company's interests in Canada were sold in 1992. In accordance with
regulations established by the SEC, the reserve estimates were based on economic
and operating conditions existing at the end of the respective years.
 
     Future prices for natural gas were based on market prices as of each year
end and contract terms, including fixed and determinable price escalations.
Market prices as of each year end were used for future sales of oil, condensate
and natural gas liquids. Future operating costs, production and ad valorem taxes
and capital costs were based on current costs as of each year end, with no
escalation.
 
     Over 70% of the Company's equivalent proved reserves (based on a factor of
6 thousand cubic feet (Mcf) of gas per barrel of liquids) at December 31, 1992
are natural gas. The natural gas prices in effect at December 31, 1992 (having a
weighted average of $1.94 per Mcf) were used in accordance with SEC regulations
but may not be the most appropriate or representative prices to use for
estimating reserves since such prices were influenced by the seasonal demand for
natural gas. The average price received by the Company for sales of natural gas
in 1992 was $1.66 per Mcf. Assuming all other variables used in the calculation
of reserved data are held constant, the Company estimates that each $.10 change
in the price per Mcf for natural gas production would affect the Company's
estimated future net cash flows and present value thereof, before income taxes,
by $115 million and $54 million, respectively. At December 31, 1992, the
Company's standardized measure of future net cash flows from proved reserves
(Standardized Measure) and the pre-tax Standardized Measure were less than the
net book value of oil and gas properties by approximately $225 million and $94
million, respectively. The Company believes that the ultimate future value to be
received for production from its oil and gas properties will be greater than the
current net book value of its oil and gas properties.
 
     There are numerous uncertainties inherent in estimating quantities of
proved reserves and in projecting the future rates of production and timing of
development expenditures. Reserve data represent estimates only and should not
be construed as being exact. Moreover, the Standardized Measure should not be
construed as the current market value of the proved oil and gas reserves or the
costs that would be incurred to obtain equivalent reserves. A market value
determination would include many additional factors including (i) anticipated
future changes in oil and gas prices, production and development costs; (ii) an
allowance for return on investment; (iii) the value of additional reserves, not
considered proved at present, which may be recovered as a result of further
exploration and development activities; and (iv) other business risks.
 
                                      F-43
<PAGE>   122
 
                                   MESA INC.
 
                CAPITALIZED COSTS AND COSTS INCURRED (UNAUDITED)
 
     Capitalized costs relating to oil and gas producing activities at December
31, 1992, 1991 and 1990 and the costs incurred during the years then ended are
set forth below (in thousands):
 
<TABLE>
<CAPTION>
                                                            1992           1991           1990
                                                         ----------     ----------     ----------
<S>                                                      <C>            <C>            <C>
Capitalized Costs
  Proved properties....................................  $1,850,793     $1,785,244     $2,436,199
  Unproved properties..................................         762          4,980         20,500
  Accumulated depreciation, depletion and
     amortization......................................    (589,720)      (481,218)      (678,205)
                                                         ----------     ----------     ----------
          Net..........................................  $1,261,835     $1,309,006     $1,778,494
                                                         ----------     ----------     ----------
                                                         ----------     ----------     ----------
Costs Incurred
  Proved properties....................................  $       64     $      545     $      510
  Unproved properties..................................          63          4,779            549
  Exploration costs....................................      15,157          7,924          8,918
  Development costs....................................       6,911         12,446         24,720
  Plant facilities, gathering systems and
     compressors.......................................      49,526         10,291          6,934
                                                         ----------     ----------     ----------
          Total........................................  $   71,721     $   35,985     $   41,631
                                                         ----------     ----------     ----------
                                                         ----------     ----------     ----------
Depreciation, depletion and amortization...............  $  110,340     $  112,860     $  156,641
                                                         ----------     ----------     ----------
                                                         ----------     ----------     ----------
</TABLE>
 
                                      F-44
<PAGE>   123
 
                                   MESA INC.
 
                  ESTIMATED QUANTITIES OF RESERVES (UNAUDITED)
                            YEARS ENDED DECEMBER 31
 
<TABLE>
<CAPTION>
                                                                          NATURAL GAS LIQUIDS,
                                            NATURAL GAS                    OIL AND CONDENSATE
                                 ---------------------------------    ----------------------------
                                   1992        1991        1990        1992       1991      1990
                                 ---------   ---------   ---------    -------   --------   -------
                                              (MMcF)                            (MBbLS)  
<S>                              <C>         <C>         <C>          <C>       <C>        <C>
Proved Reserves
  Beginning of year............  1,367,968   1,920,797   2,110,219     83,225    101,667    86,595
     Extensions and
       discoveries.............     37,100       2,643      14,670      7,591      1,250        42
     Purchases of producing
       properties..............        583       1,267       3,774          9         46        27
     Revisions of previous
       estimates...............    (24,462)    (95,228)    (61,277)     3,028     (4,067)   20,795
     Sales of producing
       properties..............    (15,613)   (352,989)     (9,256)      (637)   (10,179)     (559)
     Production................    (89,527)   (108,522)   (137,333)    (5,824)    (5,492)   (5,233)
                                 ---------   ---------   ---------    -------   --------   -------
  End of year..................  1,276,049   1,367,968   1,920,797     87,392     83,225   101,667
                                 ---------   ---------   ---------    -------   --------   -------
                                 ---------   ---------   ---------    -------   --------   -------
Proved Developed Reserves
  Beginning of year............  1,338,856   1,853,523   1,986,157     82,406     99,494    84,348
                                 ---------   ---------   ---------    -------   --------   -------
                                 ---------   ---------   ---------    -------   --------   -------
  End of year..................  1,223,672   1,338,856   1,853,523     82,439     82,406    99,494
                                 ---------   ---------   ---------    -------   --------   -------
                                 ---------   ---------   ---------    -------   --------   -------
</TABLE>
 
- ---------------
 
- - Proved natural gas liquids, oil and condensate reserve quantities include oil
  and condensate reserves at December 31 of the respective years as follows:
  1992, 7,268 MBbls; 1991, 3,956 MBbls; and 1990, 9,880 MBbls.
 
- - In addition to the proved reserves disclosed above, the Company owned proved
  helium and carbon dioxide (CO2) reserves at December 31 of the respective
  years as follows: 1992, 5,634 MMcf of helium and 46,457 MMcf of CO2; 1991,
  5,705 MMcf of helium and 44,837 MMcf of CO2; 1990, 5,658 MMcf of helium and
  44,797 MMcf of CO2.
 
- - The General Partner's 4.14% minority interest in the proved natural gas and
  natural gas liquids, oil and condensate reserves of the Company at December 31
  of the respective years was as follows: 1992, 52,828 MMcf and 3,618 MBbls,
  respectively; 1991, 56,634 MMcf and 3,446 MBbls, respectively; and 1990,
  79,521 MMcf and 4,209 MBbls, respectively.
 
                                      F-45
<PAGE>   124
 
                                   MESA INC.
 
                 STANDARDIZED MEASURE OF FUTURE NET CASH FLOWS
                        FROM PROVED RESERVES (UNAUDITED)
                                  DECEMBER 31
                                 (IN THOUSANDS)
 
<TABLE>
<CAPTION>
                                                         1992           1991           1990
                                                      ----------     ----------     ----------
<S>                                                   <C>            <C>            <C>
Future cash inflows.................................  $3,802,614     $4,078,322     $6,151,195
Future production and development costs
  Operating costs and production taxes..............  (1,271,799)    (1,297,999)    (1,580,926)
  Development and abandonment costs.................    (122,860)      (181,350)      (201,542)
Future income taxes.................................    (302,492)      (394,743)      (808,501)
                                                      ----------     ----------     ----------
Future net cash flows...............................   2,105,463      2,204,230      3,560,226
  Discount at 10% per annum.........................  (1,068,282)    (1,209,016)    (1,893,078)
                                                      ----------     ----------     ----------
Standardized Measure................................  $1,037,181     $  995,214     $1,667,148
                                                      ----------     ----------     ----------
                                                      ----------     ----------     ----------
Future net cash flows before income taxes...........  $2,407,955     $2,598,973     $4,368,727
                                                      ----------     ----------     ----------
                                                      ----------     ----------     ----------
Standardized Measure before income taxes............  $1,167,694     $1,181,013     $2,054,117
                                                      ----------     ----------     ----------
                                                      ----------     ----------     ----------
</TABLE>
 
- ---------------
 
- - The estimate of future income taxes is based on the future net cash flows from
  proved reserves adjusted for the tax basis of the oil and gas properties but
  without consideration of general and administrative and interest expenses.
 
- - The General Partner's 4.14% minority interest in the Standardized Measure at
  December 31 of the respective years was as follows: 1992, $42.9 million; 1991,
  $41.2 million; and 1990, $69.0 million.
 
                                      F-46
<PAGE>   125
 
                                   MESA INC.
 
                CHANGES IN THE STANDARDIZED MEASURE (UNAUDITED)
                            YEARS ENDED DECEMBER 31
                                 (IN THOUSANDS)
 
<TABLE>
<CAPTION>
                                                               1992        1991        1990
                                                             ---------   ----------   ----------
<S>                                                          <C>         <C>         <C>
Standardized Measure at beginning of year..................  $ 995,214   $1,667,148  $1,715,600
                                                             ---------   ----------   ----------
Revisions of reserves proved in prior years
  Changes in prices and production costs...................    (77,527)    (365,430)    (126,455)
  Changes in quantity estimates............................     (3,995)     (83,342)      90,353
  Changes in estimates of future development and
     abandonment costs.....................................     (2,468)     (30,088)     (41,443)
  Net change in income taxes...............................     55,287      201,170        3,111
  Accretion of discount....................................    118,101      205,412      210,568
  Other, primarily timing of production....................     12,687      (86,815)     (16,517)
                                                             ---------   ----------   ----------
          Total revisions..................................    102,085     (159,093)     119,617
Extensions, discoveries and other additions, net of future
  production and development costs.........................     65,737       12,013       47,776
Purchases of proved properties.............................        457        1,952        3,008
Sales of oil and gas produced, net of production costs.....   (173,552)    (182,235)    (235,298)
Sales of producing properties..............................    (14,473)    (367,308)     (15,209)
Previously estimated development and abandonment costs
  incurred during the period...............................     61,713       22,737       31,654
                                                             ---------   ----------   ----------
Net changes in Standardized Measure........................     41,967     (671,934)     (48,452)
                                                             ---------   ----------   ----------
Standardized Measure at end of year........................  $1,037,181  $  995,214   $1,667,148
                                                             ---------   ----------   ----------
                                                             ---------   ----------   ----------
</TABLE>
 
                                      F-47
<PAGE>   126
 
                                   MESA INC.
 
                         QUARTERLY RESULTS (UNAUDITED)
                                 QUARTERS ENDED
                     (IN THOUSANDS, EXCEPT PER SHARE DATA)
 
<TABLE>
<CAPTION>
                                                 MARCH 31    JUNE 30     SEPTEMBER 30    DECEMBER 31
                                                 --------    --------    ------------    -----------
<S>                                              <C>         <C>         <C>             <C>
1992
  Revenues.....................................  $ 58,919    $ 51,556      $ 48,171       $  78,466
                                                 --------    --------    ------------    -----------
                                                 --------    --------    ------------    -----------
  Gross profit.................................  $ 44,181    $ 36,733      $ 33,608       $  60,100
                                                 --------    --------    ------------    -----------
                                                 --------    --------    ------------    -----------
  Operating income (loss)......................  $  9,173    $ (2,479)     $    172       $  19,355
                                                 --------    --------    ------------    -----------
                                                 --------    --------    ------------    -----------
  Net loss.....................................  $(21,973)   $(20,622)     $(29,128)      $ (17,509)
                                                 --------    --------    ------------    -----------
                                                 --------    --------    ------------    -----------
  Net loss per common share....................  $   (.57)   $   (.53)     $   (.76)      $    (.45)
                                                 --------    --------    ------------    -----------
                                                 --------    --------    ------------    -----------
1991
  Revenues.....................................  $ 76,244    $ 44,886      $ 43,103       $  85,313
                                                 --------    --------    ------------    -----------
                                                 --------    --------    ------------    -----------
  Gross profit.................................  $ 58,320    $ 32,833      $ 28,500       $  64,079
                                                 --------    --------    ------------    -----------
                                                 --------    --------    ------------    -----------
  Operating income.............................  $ 18,355    $    435      $     78       $  15,260
                                                 --------    --------    ------------    -----------
                                                 --------    --------    ------------    -----------
  Net loss.....................................  $(18,744)   $ (1,220)     $(34,362)      $ (24,837)
                                                 --------    --------    ------------    -----------
                                                 --------    --------    ------------    -----------
  Net loss per common share....................  $   (.49)   $   (.03)     $   (.89)      $    (.64)
                                                 --------    --------    ------------    -----------
                                                 --------    --------    ------------    -----------
</TABLE>
 
- ---------------
 
- - Gross profit consists of total revenues less lease operating expenses and
  production and other taxes.
 
- - The Company entered into an agreement in early 1992, effective to January 1,
  1991, allocating the production and reserves of the Company's West Panhandle
  field properties at 77% to the Company and 23% to a third party. Throughout
  1991 and 1992, the Company produced less than its 77% entitlement. To reflect
  the effect of the new agreement on 1991 operations, in the fourth quarter of
  1991 the Company recorded an additional $17.4 million as revenues, $13.0
  million as gas balancing receivables and $4.4 million as operating expenses
  relating to its entitlement. Throughout 1992, the Company recorded an
  additional $23.3 million as revenues, $17.2 million as gas balancing
  receivables and $6.1 million as operating expenses relating to its
  entitlement.
 
                                      F-48
<PAGE>   127
 
                                                                         ANNEX A
 
                                    GLOSSARY
 
     The following defined terms are used frequently in this Prospectus.
 
APAA.......................  Amendment to the PAA effective as of January 1,
                             1993, between MOC and CIG relating to the West
                             Panhandle field reserves.
 
"B" Contract...............  The series of contracts between Mesa and CIG which
                             establish and define Mesa's West Panhandle
                             reserves.
 
BbL........................  Barrel of oil and condensate or natural gas
                             liquids.
 
BcF........................  Billion cubic feet of natural gas.
 
Bcfe.......................  Billion cubic feet of natural gas equivalents.
 
Btu........................  British thermal unit.
 
Capital....................  Mesa Capital Corporation, a Delaware corporation
                             and a wholly-owned subsidiary of MOC.
 
CIG........................  Colorado Interstate Gas Company.
 
Code.......................  The Internal Revenue Code of 1986, as amended.
 
Commission.................  The Securities and Exchange Commission.
 
Common Stock...............  The common stock, par value $.01 per share, of the
                             Company.
 
Company....................  MESA Inc., a Texas corporation.
 
Convertible Notes..........  0% Convertible Notes due June 30, 1998, issued by
                             the Company, MOLP and Capital, all of which have
                             been converted into Common Stock.
 
Corporate Conversion.......  The transaction that reorganized the business of
                             the Partnership into the Company on December 31,
                             1991.
 
Credit Agreement...........  The amended and restated revolving credit agreement
                             among the Company, MOC, the Banks and Societe
                             Generale, Southwest Agency, as Agent, as the same
                             may be amended, modified or supplemented from time
                             to time.
 
D&M........................  DeGolyer and MacNaughton, independent petroleum
                             engineering consultants.
 
Discount Notes.............  The Secured Notes and the Unsecured Notes.
 
Exchange Act...............  The Securities Exchange Act of 1934.
 
Exchange Offer.............  The Obligors' offer to exchange Secured Notes,
                             Unsecured Notes and Convertible Notes for
                             Subordinated Notes, which was completed on August
                             26, 1993.
 
Fain Plant.................  Mesa's natural gas processing plant in the West
                             Panhandle field.
 
FERC.......................  The Federal Energy Regulatory Commission.
 
HCLP.......................  Hugoton Capital Limited Partnership, a Delaware
                             limited partnership and indirect subsidiary of the
                             Company.
 
                                       A-1
<PAGE>   128
 
HCLP Secured Notes.........  The secured notes issued by HCLP in the initial
                             aggregate principal amount of $616.5 million and
                             secured by Mesa's interest in the Hugoton field.
 
Hugoton Field..............  The Chase and Council Grove formations of the
                             Hugoton and Panoma fields of southwestern Kansas.
 
KCC........................  The Kansas Corporation Commission.
 
MBbl.......................  Thousand barrels.
 
MBtu.......................  Thousand British thermal units.
 
Mcf........................  Thousand cubic feet, a standard unit of volume
                             measurement for natural gas.
 
Mcfe.......................  Thousand cubic feet of natural gas equivalents.
 
Mesa.......................  The Company, its subsidiaries and predecessors (the
                             Partnership and Original Mesa).
 
Mesa Environmental.........  Mesa Environmental Ventures Limited Partnership, a
                             Delaware limited partnership and indirect
                             subsidiary of the Company.
 
MHC........................  Mesa Holding Co., a Delaware corporation.
 
MHLP.......................  Mesa Holding Limited Partnership, a Delaware
                             limited partnership and a subsidiary of the
                             Company, predecessor to MHC.
 
MMBtu......................  Million British thermal units.
 
MMcf.......................  Million cubic feet (or 1,000 Mcf) of natural gas.
 
MMcfe......................  Million cubic feet of equivalent natural gas
                             reserves.
 
MMC........................  Mesa Midcontinent Co., a Delaware corporation.
 
MMLP.......................  Mesa Midcontinent Limited Partnership, a Delaware
                             limited partnership and a subsidiary of the
                             Company, predecessor to MMC.
 
MOC........................  Mesa Operating Co., a Delaware corporation.
 
MOLP.......................  Mesa Operating Limited Partnership, a Delaware
                             limited partnership and a subsidiary of the
                             Company, predecessor to MOC.
 
natural gas equivalents....  A volume, expressed in Mcf's of natural gas, which
                             includes not only natural gas but also oil or
                             natural gas liquids converted to an equivalent
                             quantity of natural gas on an energy equivalent
                             basis. Equivalent gas reserves are based on a
                             conversion factor of 6 Mcf of gas per barrel of
                             liquids.
 
NGPA.......................  The Natural Gas Policy Act of 1978.
 
NGV........................  Natural gas vehicles.
 
Obligors...................  The Company, MOC and Capital.
 
Original Mesa..............  Mesa Petroleum Co., a Delaware corporation and a
                             predecessor in interest to the Company.
 
PAA........................  Production Allocation Agreement, effective January
                             1, 1991, between MOC and CIG defining production
                             rights and ownership of reserves from the West
                             Panhandle field.
 
                                       A-2
<PAGE>   129
 
Partnership................  Mesa Limited Partnership, a Delaware limited
                             partnership and predecessor in interest to the
                             Company.
 
Prospectus.................  This Prospectus.
 
Registration Statement.....  The Registration Statement on Form S-1
                             (Registration No. 33-     ) of the Obligors
                             initially filed with the SEC on January 14, 1994,
                             together with all amendments and exhibits thereto,
                             of which this Prospectus is a part.
 
Secured Notes..............  12 3/4% Secured Discount Notes due June 30, 1998,
                             issued by the Company, MOC and Capital and offered
                             hereby.
 
Securities Act.............  The Securities Act of 1933.
 
Subordinated Notes.........  12% Subordinated Notes and 13 1/2% Subordinated
                             Notes.
 
Tcf........................  Trillion cubic feet of natural gas.
 
Tcfe.......................  Trillion cubic feet of natural gas equivalents.
 
12% Subordinated Notes.....  12% Subordinated Notes due August 1, 1996, issued
                             by the Company, MOC and Capital.
 
13 1/2% Subordinated
Notes......................  13 1/2% Subordinated Notes due May 1, 1999, issued
                             by the Company, MOC and Capital.
 
Unsecured Notes............  12 3/4% Discount Notes due June 30, 1996, issued by
                             the Company, MOC and Capital.
 
West Panhandle Field.......  The properties owned by Mesa located in the
                             panhandle area of northwest Texas.
 
Williams...................  Williams Natural Gas Company.
 
WRI........................  Western Resources, Inc., formerly The Kansas Power
                             and Light Company.
 
                                       A-3
<PAGE>   130
 
- ------------------------------------------------------
- ------------------------------------------------------
     NO DEALER, SALESPERSON OR OTHER INDIVIDUAL 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. IF GIVEN
OR MADE, SUCH INFORMATION OR REPRESENTATIONS MUST NOT BE RELIED UPON AS HAVING
BEEN AUTHORIZED BY THE COMPANY OR ANY AGENT OR UNDERWRITER. THIS PROSPECTUS DOES
NOT CONSTITUTE AN OFFER TO SELL, OR A SOLICITATION OF AN OFFER TO BUY, THE
SECURED NOTES IN ANY JURISDICTION WHERE, OR TO 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
ANY IMPLICATION THAT THERE HAS NOT BEEN ANY CHANGE IN THE FACTS SET FORTH IN
THIS PROSPECTUS OR IN THE AFFAIRS OF THE COMPANY SINCE THE DATE HEREOF.
                            ------------------------
                               TABLE OF CONTENTS
 
<TABLE>
<CAPTION>
                                        PAGE
                                        ----
<S>                                     <C>
Additional Information.................   2
Summary................................   3
Risk Factors...........................   9
The Company............................  13
Unocal Litigation and Settlement.......  15
Use of Proceeds........................  16
Market Prices of Secured Notes.........  16
Historical and Pro Forma
  Capitalization.......................  17
Selected Financial Information.........  18
Management's Discussion and Analysis
  of Financial Condition and Results
  of Operations........................  19
Business...............................  27
Regulation and Prices..................  38
Management.............................  41
Executive Compensation.................  44
Security Ownership of Principal Owners
  and Management.......................  50
Description of the Secured Notes.......  52
Certain U.S. Federal Income Tax
  Consequences.........................  73
Plan of Distribution...................  75
Legal Opinions.........................  76
Experts................................  76
Index to Financial Statements.......... F-1
</TABLE>
 
- ------------------------------------------------------
- ------------------------------------------------------
 
- ------------------------------------------------------
- ------------------------------------------------------
 
                                  $51,000,000
 
                                  {MESA LOGO}

                         12 3/4% SECURED DISCOUNT NOTES
 
                               DUE JUNE 30, 1998
                              --------------------
                                   PROSPECTUS
                              --------------------
                                               , 1994
- ------------------------------------------------------
- ------------------------------------------------------
<PAGE>   131
 
                                    PART II
 
                     INFORMATION NOT REQUIRED IN PROSPECTUS
 
ITEM 13. OTHER EXPENSES OF ISSUANCE AND DISTRIBUTIONS
 
     The following are the estimated expenses (other than underwriting discounts
and commissions) of the issuance and distribution of the securities being
registered payable by the Company.
 
<TABLE>
        <S>                                                                  <C>
        Securities and Exchange Commission registration fee................  $15,388
        Printing and engraving expenses....................................     *
        Blue Sky filing fees and expenses..................................     *
        Accountants' fees..................................................     *
        Counsel fees.......................................................     *
        Miscellaneous......................................................     *
                                                                             -------
                  Total....................................................  $  *
                                                                             -------
                                                                             -------
</TABLE>
 
- ---------------
 
* To be provided by amendment.
 
ITEM 14. INDEMNIFICATION OF DIRECTORS AND OFFICERS.
 
     Article 2.02-1 of the Texas Business Corporation Act provides that a
corporation may indemnify any director or officer who was, is or is threatened
to be made a named defendant or respondent in a proceeding because he is or was
a director or officer, provided that the director or officer (i) conducted
himself in good faith, (ii) reasonably believed (a) in the case of conduct in
his official capacity, that his conduct was in the corporation's best interests,
(b) in all other cases, that his conduct was at least not opposed to the
corporation's best interests and (iii) in the case of any criminal proceeding,
had no reasonable cause to believe his conduct was unlawful. Subject to certain
exceptions, a director or officer may not be indemnified if the person is found
liable to the corporation or if the person is found liable on the basis that he
improperly received a personal benefit. Under Texas law, reasonable expenses
incurred by a director or officer may be paid or reimbursed by the corporation
in advance of a final disposition of the proceeding after the corporation
receives a written affirmation by the director of his good faith belief that he
has met the standard of conduct necessary for indemnification and a written
undertaking by or on behalf of the director to repay the amount if it is
ultimately determined that the director or officer is not entitled to
indemnification by the corporation. Texas law requires a corporation to
indemnify an officer or director against reasonable expenses incurred in
connection with the proceeding in which he is named defendant or respondent
because he is or was a director or officer if he is wholly successful in defense
of the proceeding.
 
     Texas law also permits a corporation to purchase and maintain insurance or
another arrangement on behalf of any person who is or was a director or officer
against any liability asserted against him and incurred by him in such a
capacity or arising out of his status as such a person, whether or not the
corporation would have the power to indemnify him against that liability under
Article 2.02-1.
 
     The Company's Bylaws provide for the indemnification of its officers and
directors, and the advancement to them of expenses in connection with
proceedings and claims, to the fullest extent permitted by the Texas Business
Corporation Act. The Company has also entered into indemnification agreements
with its executive officers and directors that contractually provide for
indemnification and expense advancement. Both the Bylaws and the agreements
include related provisions meant to facilitate the indemnitees' receipt of such
benefits. These provisions cover, among other things: (i) specification of the
method of determining entitlement to indemnification and the selection of
independent counsel that will in some cases make such determination, (ii)
specification of certain time periods by which certain payments or
determinations must be made and actions must be taken and (iii) the
establishment of certain presumptions in favor of an indemnitee. The benefits of
certain of these provisions are available to an indemnitee only if there has
been a change in control (as defined). In addition, the Company carries
customary directors' and officers' liability insurance policies for its
directors and officers. Furthermore, the Bylaws and agreements with directors
and officers provide for indemnification for amounts (i) in respect of the
deductibles for such insurance policies, (ii) that exceed the liability limits
of such insurance policies and (iii) that would have been covered by prior
insurance
 
                                      II-1
<PAGE>   132
 
policies of the Company or its predecessors. Such indemnification may be made
even though directors and officers would not otherwise be entitled to
indemnification under other provisions of the Bylaws or such agreements.
 
     The above discussion of the Company's Bylaws and of Article 2.01-1 of the
Texas Business Corporation Act is not intended to be exhaustive and is
respectively qualified in its entirety by such statute and the Bylaws.
 
     Section 145 of the Delaware General Corporation Law (the "DGCL" permits a
corporation to indemnify any director or officer of the corporation against
expenses (including attorney's fees), judgments, fines and amounts paid in
settlement actually and reasonably incurred in connection with any action, suit
or proceeding brought by reason of the fact that such person is or was a
director or officer of the corporation, if such person acted in good faith and
in a manner that he reasonably believed to be in or not opposed to the best
interests of the corporation and, with respect to any criminal action or
proceeding, if he had no reason to believe his conduct was unlawful. In a
derivative action (i.e., one brought by or on behalf of the corporation),
indemnification may be made only for expenses actually and reasonably incurred
by any director or officer in connection with the defense or settlement of such
an action or suit, if such person acted in good faith and in a manner that he
reasonably believed to be in or not opposed to the best interests of the
corporation, except that no indemnification shall be made if such person shall
have been adjudged to be liable to the corporation, unless and only to the
extent that the court in which the action or suit was brought shall determine
that the defendant is fairly and reasonably entitled to indemnity for such
expenses despite such adjudication of liability.
 
     Delaware law also permits a corporation to purchase and maintain insurance
on behalf of any person who is or was a director or officer against any
liability asserted against him and incurred by him in such capacity or arising
out of his status as such, whether or not the corporation have the power to
indemnify him against that liability under Section 145 of the DGCL.
 
     MOC's Bylaws provide that MOC may indemnify each person who is involved in
any litigation or other proceeding because such person is or was a director or
officer of MOC or its subsidiaries or is or was serving as an officer or
director of another entity at the request of MOC, against all expenses
reasonably incurred in connection therewith. Such indemnification shall be made
upon a determination by the Board of Directors, independent legal counsel or the
stockholders of the corporation that such indemnification is proper in the
circumstances because such person has met the applicable standard of conduct.
The Bylaws also provide that MOC shall indemnify a director or officer against
such expenses to the extent that he has been successful on the merits or
otherwise in defense of any such litigation or other proceeding. The Bylaws also
provide that the right to indemnification includes the right to be paid expenses
incurred in defending any proceeding in advance of its final disposition;
provided, however, that such advance payment will only be made upon the delivery
to MOC of an undertaking, by or on behalf of the director or officer, to repay
all amounts so advanced if it is ultimately determined that such director or
officer is not entitled to indemnification.
 
     MOC's Certificate of Incorporation provides that the personal liability of
a director of the corporation shall be limited to the fullest extent permitted
by the DGCL. Pursuant to Section 102(b)(7) of the DGCL, Article Sixth of MOC's
Certificate of Incorporation eliminates the personal liability of a director to
the corporation or its stockholders for monetary damages for breach of fiduciary
duty as a director, except for liabilities arising (i) from any breach of the
director's duty of loyalty to the corporation or its stockholders, (ii) from
acts or omissions not in good faith or which involve intentional misconduct or a
knowing violation of law, (iii) under Section 174 of the DGCL, or (iv) from any
transaction from which the director derived an improper personal benefit.
 
     The above discussion of MOC's Bylaws and Certificate of Incorporation is
not intended to be exhaustive and is respectively qualified in its entirety by
such documents.
 
     Article V of the Bylaws of Capital includes the following provision:
 
     Section 1. Indemnification of Officers and Directors. Each person who shall
have served as a director or officer of this Corporation, or at its request as
director or officer of another corporation in which it now owns or may hereafter
own shares of capital stock or of which it now is or may hereafter be a
creditor, shall be indemnified by the Corporation to the maximum extent
permitted by applicable law against expenses and
 
                                      II-2
<PAGE>   133
 
costs (including attorneys' fees) reasonably incurred by him in connection with
any claim asserted against him, by action in court or otherwise, by reason of
being or having been such director or officer. The foregoing right of
indemnification shall not be exclusive of other rights to which he may be
entitled under any agreement, vote of shareholders or otherwise.
 
     The above discussion of Capital's Bylaws, and of the DGCL, is not intended
to be exhaustive and is respectively qualified in its entirety by such documents
and statute.
 
ITEM 16. EXHIBITS AND FINANCIAL STATEMENT SCHEDULES.
 

<TABLE>
<CAPTION>
      Exhibits
        <S>          <C>
        *3.1         -- Amended and Restated Articles of Incorporation of MESA Inc. (Exhibit
                        3(b) to MESA Inc.'s Registration Statement on Form S-4, Registration
                        No. 33-42104).
        *3.2         -- Amended and Restated Bylaws of MESA Inc. (Exhibit 3(c) to MESA Inc.'s
                        Registration Statement on Form S-4, Registration No. 33-42104).
         3.3         -- Certificate of Incorporation of Mesa Operating Co.
         3.4         -- Bylaws of Mesa Operating Co.
         3.5         -- Certificate of Incorporation of Mesa Capital Corporation.
         3.6         -- Bylaws of Mesa Capital Corporation.
        *4.1         -- Indenture dated as of May 1, 1993, among MESA Inc., Mesa Operating
                        Limited Partnership, Mesa Capital Corporation and Harris Trust and
                        Savings Bank, as trustee, including (a) a form of Secured Note, (b) a
                        form of Deed of Trust, Assignment of Production, Security Agreement
                        and Financing Statement, dated as of May 1, 1993, between MOLP and
                        Harris Trust and Savings Bank, as trustee, securing the Secured
                        Notes, and (c) a form of Security Agreement, Pledge and Financing
                        Statement dated as of May 1, 1993 between MOLP and Harris Trust and
                        Savings Bank, as trustee, securing the Secured Notes (Exhibit 4(f) to
                        MESA Inc.'s Form 10-Q/A dated June 30, 1993).
         4.2         -- First Supplemental Indenture dated as of January 5, 1994, among MESA
                        Inc., Mesa Operating Co., Mesa Capital Corporation and Harris Trust
                        and Savings Bank, as trustee.
        *4.3         -- Indenture dated as of May 1, 1993, among MESA Inc., Mesa Operating
                        Limited Partnership, Mesa Capital Corporation and American Stock
                        Transfer & Trust Company, as trustee, including a form of Unsecured
                        Notes (Exhibit 4(g) to MESA Inc.'s Form 10-Q/A dated June 30, 1993).
         4.4         -- First Supplemental Indenture dated as of January 5, 1994, among MESA
                        Inc., Mesa Operating Co., Mesa Capital Corporation and American Stock
                        Transfer & Trust Company, as trustee.
        *4.5         -- Indenture dated as of May 1, 1993, among MESA Inc., Mesa Operating
                        Limited Partnership, Mesa Capital Corporation and American Stock
                        Transfer & Trust Company, as trustee, including a form of Convertible
                        Notes (Exhibit 4(h) to MESA Inc.'s Form 10-Q/A dated June 30, 1993).
        *4.6         -- Indenture dated August 14, 1986, among Mesa Capital Corporation, Mesa
                        Limited Partnership, Mesa Operating Limited Partnership and Mellon
                        Bank, N.A., as trustee (subsequently replaced by Texas Commerce Bank,
                        National Association, as successor trustee) (Exhibit 4(d) to Mesa
                        Limited Partnership's Form 10-Q dated September 30, 1986).
</TABLE>
 
                                      II-3
<PAGE>   134
 
<TABLE>
        <S>          <C>
        *4.7         -- Supplemental Indenture dated July 31, 1987, among Mesa Capital
                        Corporation, Mesa Limited Partnership, Mesa Operating Limited
                        Partnership and Mellon Bank, N.A., as trustee (subsequently replaced
                        by Texas Commerce Bank, National Association, as successor trustee)
                        (Exhibit 4(e) to Mesa Limited Partnership's Form 10-Q dated September
                        30, 1987).
        *4.8         -- Second Supplemental Collateral Trust Indenture dated as of December
                        31, 1991, among Mesa Capital Corporation, MESA Inc., Mesa Operating
                        Limited Partnership and Texas Commerce Bank National Association, as
                        successor trustee (Exhibit 4(c) to MESA Inc.'s Form 10-K dated
                        December 31, 1991).
        *4.9         -- Third Supplemental Collateral Trust Indenture dated as of April 30,
                        1992, among Mesa Capital Corporation, as Issuer, MESA Inc. and Mesa
                        Operating Limited Partnership and Texas Commerce Bank National
                        Association, as successor trustee (Exhibit 4(j) to MESA Inc.'s Form
                        10-Q dated June 30, 1992).
        *4.10        -- Fourth Supplemental Collateral Trust Indenture dated as of August 26,
                        1993, among Mesa Capital Corporation, MESA Inc., Mesa Operating
                        Limited Partnership and Texas Commerce Bank National Association, as
                        successor trustee (Exhibit 4(e) to MESA Inc.'s Form 10-Q/A dated June
                        30, 1993).
         4.11        -- Fifth Supplemental Collateral Trust Indenture dated as of January 5,
                        1994, among MESA Inc., Mesa Operating Co., Mesa Capital Corporation
                        and Texas Commerce Bank National Association, as successor trustee.
        *4.12        -- Indenture dated May 1, 1989, among Mesa Capital Corporation, Mesa
                        Limited Partnership, Mesa Operating Limited Partnership, and Texas
                        Commerce Bank National Association, as trustee (Exhibit 4(c) to Mesa
                        Limited Partnership's Form 10-Q dated March 31, 1989).
        *4.13        -- First Supplemental Indenture dated as of December 31, 1991, among
                        Mesa Capital Corporation, MESA Inc., Mesa Operating Limited
                        Partnership and Texas Commerce Bank National Association, as trustee
                        (Exhibit 4(e) to MESA Inc.'s Form 10-K dated December 31, 1991).
        *4.14        -- Second Supplemental Indenture dated as of April 30, 1992, among Mesa
                        Capital Corporation, MESA Inc., Mesa Operating Limited Partnership
                        and Texas Commerce Bank National Association, as trustee (Exhibit
                        4(k) to MESA Inc.'s Form 10-Q dated June 30, 1992).
        *4.15        -- Third Supplemental Indenture dated as of August 26, 1993, among Mesa
                        Capital Corporation, MESA Inc., Mesa Operating Limited Partnership
                        and Texas Commerce Bank National Association, as trustee (Exhibit
                        4(l) to MESA Inc.'s Form 10-Q/A dated June 30, 1993).
         4.16        -- Fourth Supplemental Indenture dated as of January 5, 1994, among MESA
                        Inc., Mesa Operating Co., Mesa Capital Corporation and Texas Commerce
                        Bank National Association, as trustee.
        *4.17        -- Indenture dated as of May 30, 1991, among Hugoton Capital Limited
                        Partnership, Hugoton Capital Corporation and Bankers Trust Company,
                        as trustee (Exhibit 4(e) to Mesa Limited Partnership's Form 10-Q
                        dated June 30, 1991).
        *4.18        -- First Supplemental Indenture dated September 1, 1991, among Hugoton
                        Capital Limited Partnership, Hugoton Capital Corporation and Bankers
                        Trust Company, as trustee (Exhibit 4(i) to MESA Inc.'s Registration
                        Statement on Form S-4, Registration No. 33-42104).
</TABLE>
 
                                      II-4
<PAGE>   135
 
<TABLE>
       <S>           <C>
        *4.19        -- Amended and Restated Mortgage, Assignment, Security Agreement and
                        Financing Statement dated June 12, 1991 from Hugoton Capital Limited
                        Partnership to Bankers Trust Company, as Collateral Agent (Exhibit
                        4(f) to Mesa Limited Partnership's Form 10-Q dated June 30, 1991).
        *4.20        -- Amended and Restated Credit Agreement dated as of May 1, 1993, among
                        MESA Inc., Mesa Operating Limited Partnership, the Banks party
                        thereto and Societe Generale, Southwest Agency, as Agent (Exhibit
                        4.17 to MESA Inc.'s Registration Statement on Form S-4, Registration
                        No. 33-53706).
         4.21        -- Assignment and Assumption Agreement dated as of January 5, 1994,
                        among MESA Inc., Mesa Operating Co., Mesa Operating Limited
                        Partnership, Pickens Operating Co., the Banks party to the Credit
                        Agreement and the Agent with respect to the Credit Agreement.
        *4.22        -- Intercreditor Agreement dated as of August 26, 1993, among Societe
                        Generale, Southwest Agency, as agent for the Banks under the
                        Company's Credit Agreement, Harris Trust and Savings Bank, as trustee
                        with respect to the Secured Notes, and American Stock Transfer &
                        Trust Company, as trustee with respect to the Unsecured Notes and the
                        Convertible Notes (Exhibit 4.18 to MESA Inc.'s Registration Statement
                        on Form S-4, Registration No. 33-53706).
                     -- The Company agrees to furnish the Commission, upon request, a copy of
                        any agreement defining the rights of holders of long-term debt of the
                        Company and all its subsidiaries under which the total amount of
                        securities authorized does not equal 10% of the total assets of the
                        Company and its subsidiaries on a consolidated basis.
        +5           -- Opinion of Baker & Botts, L.L.P.
        +8           -- Tax Opinion of Baker & Botts, L.L.P.
       *10.1         -- Form of First Amendment to Deferred Compensation Agreement and Life
                        Insurance Agreement between Mesa Petroleum Co. and certain officers
                        and key employees (Exhibit 10(i) to Mesa Petroleum Co.'s Form 10-K
                        dated December 31, 1980).
       *10.2         -- Hugoton (MTR) Gas Purchase Contract between The Kansas Power and
                        Light Company, buyer, and Mesa Operating Limited Partnership, seller,
                        dated effective January 1, 1990 (Exhibit 19(a) to Mesa Limited
                        Partnership's Form 10-Q dated June 30, 1989).
       *10.3         -- Supplemental Gas Purchase Contract between The Kansas Power and Light
                        Company, buyer, and Mesa Operating Limited Partnership, seller, dated
                        effective January 1, 1990 (Exhibit 19(b) to Mesa Limited
                        Partnership's Form 10-Q dated June 30, 1989).
       *10.4         -- Second Amended and Restated Consulting Agreement between Mesa Limited
                        Partnership, Mesa Operating Limited Partnership, Mesa Holding Limited
                        Partnership, Mesa Acquisition Limited Partnership and BTC Partners,
                        Inc. dated December 1, 1988 (Exhibit 10(i) to Mesa Limited
                        Partnership's Form 10-K dated December 31, 1988).
       *10.5         -- Contract dated January 3, 1928 between Colorado Interstate Gas
                        Company and Amarillo Oil Company (the "B" Contract) (Exhibit 10.1 to
                        Pioneer Corporation's Form 10-K dated December 31, 1985).
       *10.6         -- Amendments to the "B" Contract (Exhibit 10.2 to Pioneer Corporation's
                        Form 10-K dated December 31, 1985).
       *10.7         -- Gathering Charge Agreement dated January 20, 1985, as amended, with
                        respect to the "B" Contract (Exhibit 10.3 to Pioneer Corporation's
                        Form 10-K dated December 31, 1985.
</TABLE>
 
                                      II-5
<PAGE>   136
 
<TABLE>
       <S>           <C>
       *10.8         -- Agreement of Compromise and Settlement dated May 29, 1987 between
                        Mesa Operating Limited Partnership and Colorado Interstate Gas
                        Company (Exhibit 10(s) to Mesa Limited Partnership's Form 10-K dated
                        December 31, 1987).
       *10.9         -- Agreement of Sale between Pioneer Corporation and Cabot Corporation
                        dated August 29, 1984 (Exhibit 10.5 to Pioneer Corporation's Form
                        10-K dated December 31, 1985).
       *10.10        -- Gas Purchase Contract dated June 27, 1949 as amended through October
                        3, 1985 between Amarillo Oil Company and Energas Company (Exhibit
                        10.6 to Pioneer Corporation's Form 10-K dated December 31, 1985).
       *10.11        -- Settlement Agreement dated March 15, 1989, by and among Mesa
                        Operating Limited Partnership and Mesa Limited Partnership, et al.,
                        Energas Company and the City of Amarillo (Exhibit 10(k) to Mesa
                        Limited Partnership's Form 10-K dated December 31, 1990).
       *10.12        -- Copy of the Partnership's Restricted MLP Unit Plan dated August 27,
                        1987 (Exhibit 10(w) to Mesa Limited Partnership's Form 10-K dated
                        December 31, 1987).
       *10.13        -- Gas Purchase Agreement dated December 1, 1989 between Williams
                        Natural Gas Company and Mesa Operating Limited Partnership acting on
                        behalf of itself and as agent for Mesa Midcontinent Limited
                        Partnership (Exhibit 10.1 to Mesa Limited Partnership's Registration
                        Statement on Form S-3, Registration No. 33-32978).
       *10.14        -- Form of 1991 Common Stock Option Plan of MESA Inc. (Exhibit 10(n) to
                        MESA Inc.'s Registration Statement on Form S-4, Registration No.
                        33-42104).
       *10.15        -- Supplemental Stipulation and Agreement to replace the Uncontested
                        Settlement Agreement between Mesa Operating Limited Partnership and
                        Colorado Interstate Gas company with respect to deliveries of gas to
                        Amarillo Oil Company (now Mesa Operating Limited Partnership) by
                        Colorado Interstate Gas company under the "B" Contract (Exhibit 10(o)
                        to Mesa Limited Partnership's Form 10-K dated December 31, 1990.)
       *10.16        -- Purchase and Sale Agreement dated February 6, 1991, by and among Mesa
                        Limited Partnership, Mesa Operating Limited Partnership and Mesa
                        Midcontinent Limited Partnership and Seagull Energy Corporation, as
                        amended by a first amendment dated February 22, 1991, a second
                        amendment dated March 8, 1991, and a third amendment dated March 11,
                        1991 (Exhibit 1 to Mesa Limited Partnership's Form 8-K dated March 8,
                        1991).
       *10.17        -- Purchase and Sale Agreement dated February 6, 1991, by and among Mesa
                        Limited Partnership, Mesa Operating Limited Partnership and Mesa
                        Midcontinent Limited Partnership and an independent oil and gas
                        producer (Exhibit 3 to Mesa Limited Partnership's Form 8-K dated
                        March 8, 1991.)
       *10.18        -- Purchase and Sale Agreement dated March 25, 1991, by and among Mesa
                        Limited Partnership and Mesa Operating Limited Partnership and
                        Conoco, Inc. (Exhibit 5 to Mesa Limited Partnership's Form 8-K dated
                        March 8, 1991).
       *10.19        -- Incentive Bonus Plan of Mesa Operating Limited Partnership, as
                        amended, dated effective January 1, 1986 (Exhibit 10(s) to Mesa
                        Limited Partnership's Form 10-K dated December 31, 1990).
       *10.20        -- Performance Bonus Plan of Mesa Operating Limited Partnership dated
                        effective January 1, 1990 (Exhibit 10(t) to Mesa Limited
                        Partnership's Form 10-K dated December 3, 1990).
</TABLE>
 
                                      II-6
<PAGE>   137
 
<TABLE>
<S>                  <C>
       *10.21        -- Engagement Agreement dated as of July 1, 1991 between Mesa Limited
                        Partnership, Mesa Operating Limited Partnership, Mesa Holding Limited
                        Partnership, Mesa Midcontinent Limited Partnership and Mesa
                        Acquisition Limited Partnership, on the one hand, and BTC Partners,
                        Inc., on the other hand (Exhibit 10(v) to MESA Inc.'s Registration
                        Statement on Form S-4, Registration No. 33-42104).
       *10.22        -- Amended Supplemental Stipulation and Agreement between Mesa Operating
                        Limited Partnership and Colorado Interstate Gas Company filed June
                        18, 1991, with the Federal Energy Regulatory Commission as an offer
                        of partial settlement with respect to deliveries of gas to Amarillo
                        Oil Company (now Mesa Operating Limited Partnership) by Colorado
                        Interstate Gas Company under the "B" Contract (Exhibit 10(w) to MESA
                        Inc.'s Registration Statement on Form S-4, Registration No.
                        33-42104).
       *10.23        -- "B" Contract Production Allocation Agreement dated July 29, 1991,
                        effective January 1, 1991, between Colorado Interstate Gas Company
                        and Mesa Operating Limited Partnership (Exhibit 10(x) to MESA Inc.'s
                        Registration Statement on Form S-4, Registration No. 33-42104).
        10.24        -- Amendment to "B" Contract Production Allocation Agreement effective
                        as of January 1, 1993 between Colorado Interstate Gas Company and
                        Mesa Operating Limited Partnership
        10.25        -- Agreement of Compromise and Settlement dated January 11, 1994 among
                        Unocal Corporation, David Colan, MESA Inc., and certain other
                        parties.
        12           -- Ratio of Earnings to Fixed Charges
       *22           -- Subsidiaries (Exhibit 22 to MESA Inc.'s Form 10-K dated December 31,
                        1992).
        23.1         -- Consent of Arthur Andersen & Co.
        23.2         -- Consent of DeGolyer and MacNaughton.
       +23.3         -- Form of Consent of Baker & Botts, L.L.P. (included in Exhibit 5 to
                        this Registration Statement).
        24           -- Powers of Attorney (included on signature pages to this Registration
                        Statement).
       *25           -- Statement of Eligibility of Trustee (Exhibit 26) to MESA Inc.'s
                        Registration Statement on Form S-4, Registration No. 33-53706).
       *28.1         -- Letter Report of the Company (Exhibit 28 to MESA Inc.'s Form 10-K
                        dated December 31, 1992).
</TABLE>
 
- ---------------
 
* Exhibit has been incorporated by reference as indicated.
 
+ To be filed by amendment.
 
FINANCIAL STATEMENT SCHEDULES
 
<TABLE>
<CAPTION>
                                                                                           PAGE
                                                                                           ----
<S>                                                                                        <C>
Report of Independent Public Accountants.................................................  S-1
Schedule III    -- Condensed Financial Information of the Registrant.....................  S-2
Schedule V      -- Property, Plant and Equipment.........................................  S-4
Schedule VI     -- Accumulated Depreciation, Depletion and Amortization of Property,
                   Plant and Equipment...................................................  S-5
Schedule X      -- Supplementary Income Statement Information............................  S-6
</TABLE>
 
                                      II-7
<PAGE>   138
 
ITEM 17. UNDERTAKINGS.
 
     The undersigned registrant hereby undertakes:
 
     Insofar as indemnification for liabilities arising under the Securities Act
of 1933 may be permitted to directors, officers and controlling persons of the
registrant pursuant to the foregoing provisions, 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 or controlling person of the registrant
in the successful defense of any action, suit or proceeding) is asserted by such
director, 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.
 
     To file, during any period in which offers or sales are being made, a
post-effective amendment to this registration statement: (i) to include any
prospectus required by section 10(a)(3) of the Securities Act of 1933; (ii) to
reflect in the prospectus any facts or events arising after the effective date
of the registration statement (or the most recent post-effective amendment
thereof) which, individually or in the aggregate represent a fundamental change
in the information set forth in the registration statement; (iii) to include any
material information with respect to the plan of distribution not previously
disclosed in the registration statement or any material change to such
information in the registration statement.
 
     That, for the purpose of determining any liability under the Securities Act
of 1933, each such post-effective amendment 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.
 
     To remove from registration by means of a post-effective amendment any of
the securities being registered which remain unsold at the termination of the
offering.
 
                                      II-8
<PAGE>   139
 
                                   SIGNATURES
 
     Pursuant to the requirements of the Securities Act, the registrant has duly
caused this registration statement or amendments to be signed on its behalf by
the undersigned, thereunto duly authorized, in the City of Dallas, State of
Texas, on January 14, 1994.
 
                                            MESA Inc.
                                            (Registrant)
 
                                            By: /s/  WILLIAM D. BALLEW
                                                ------------------------------
                                                     William D. Ballew,
                                                         Controller
 
                               POWER OF ATTORNEY
 
     The undersigned directors and executive officers of MESA Inc. hereby
constitute and appoint William D. Ballew and Charles L. Carpenter, and each of
them, with full power to act without the other and with full power of
substitution and resubstitution, our true and lawful attorneys-in-fact with full
power to execute in our name and behalf in the capacities indicated below any
and all amendments (including post-effective amendments and amendments thereto)
to this Registration Statement and to file the same, with all exhibits thereto
and other documents in connection therewith with the Securities and Exchange
Commission and hereby ratify and confirm all that such attorneys-in-fact, or
either of them, or their substitutes shall lawfully do or cause to be done by
virtue hereof.
 
     Pursuant to the requirements of the Securities Act of 1933, this
registration statement or amendment has been signed by the following persons in
the capacities and on the date indicated above.
 
<TABLE>
<CAPTION>
                  SIGNATURE                               TITLE                    DATE
- ---------------------------------------------  ----------------------------  -----------------
<S>                                            <C>                           <C>
           /s/  BOONE PICKENS                   Director and Chief Executive  January 14, 1994
        ------------------------------          Officer
                Boone Pickens                   
          
           /s/  PAUL W. CAIN                    Director, President and       January 14, 1994
        ------------------------------          Chief Operating Officer
                Paul W. Cain                    

         /s/  WILLIAM D. BALLEW                 Controller (Chief Accounting  January 14, 1994
        ------------------------------          Officer and acting Chief
              William D. Ballew                 Financial Officer)
                                                
                                                
        ------------------------------
             John S. Herrington                 Director

        /s/  WALES H. MADDEN, JR.               Director                      January 14, 1994
        ------------------------------
             Wales H. Madden, Jr.
                                               
        ------------------------------
              Fayez S. Sarofim                  Director

        /s/  ROBERT L. STILLWELL                Director                      January 14, 1994
        ------------------------------
             Robert L. Stillwell
                                               
        ------------------------------
               J.R. Walsh, Jr.                 Director
</TABLE>
 
                                      II-9
<PAGE>   140
 
                                   SIGNATURES
 
     Pursuant to the requirements of the Securities Act, the registrant has duly
caused this registration statement or amendments to be signed on its behalf by
the undersigned, thereunto duly authorized, in the City of Dallas, State of
Texas, on January 14, 1994.
 
                                            MESA OPERATING CO.
                                            (Registrant)
 
                                            By: /s/ WILLIAM D.  BALLEW
                                                --------------------------------
                                                 William D. Ballew,
                                                     Controller
 
                               POWER OF ATTORNEY
 
     The undersigned directors and executive officers of Mesa Operating Co.
hereby constitute and appoint William D. Ballew and Charles L. Carpenter, and
each of them, with full power to act without the other and with full power of
substitution and resubstitution, our true and lawful attorneys-in-fact with full
power to execute in our name and behalf in the capacities indicated below any
and all amendments (including post-effective amendments and amendments thereto)
to this Registration Statement and to file the same, with all exhibits thereto
and other documents in connection therewith with the Securities and Exchange
Commission and hereby ratify and confirm all that such attorneys-in-fact, or
either of them, or their substitutes shall lawfully do or cause to be done by
virtue hereof.
 
     Pursuant to the requirements of the Securities Act of 1933, this
registration statement or amendment has been signed by the following persons in
the capacities and on the date indicated above.
 
<TABLE>
<CAPTION>
                  SIGNATURE                               TITLE                     DATE
- ---------------------------------------------  ----------------------------   -----------------
<S>                                            <C>                            <C>
           /s/  BOONE PICKENS                  Director and Chief Executive   January 14, 1994
         ------------------------------        Officer
                Boone Pickens                  

           /s/  PAUL W. CAIN                   Director, President and        January 14, 1994
         ------------------------------        Chief Operating Officer
                Paul W. Cain                   

         /s/  WILLIAM D. BALLEW                Controller (Chief Accounting   January 14, 1994
         ------------------------------        Officer and acting Chief  
              William D. Ballew                Financial Officer)        
                                                                         
</TABLE>                                       
 
                                      II-10
<PAGE>   141
 
                                   SIGNATURES
 
     Pursuant to the requirements of the Securities Act, the registrant has duly
caused this registration statement or amendments to be signed on its behalf by
the undersigned, thereunto duly authorized, in the City of Dallas, State of
Texas, on January 14, 1994.
 
                                            MESA CAPITAL CORPORATION
                                            (Registrant)
 
                                            By: /s/  WILLIAM D. BALLEW
                                                --------------------------------
                                                     William D. Ballew,
                                                         Controller
 
                               POWER OF ATTORNEY
 
     The undersigned directors and executive officers of Mesa Capital
Corporation, hereby constitute and appoint William D. Ballew and Charles L.
Carpenter, and each of them, with full power to act without the other and with
full power of substitution and resubstitution, our true and lawful
attorneys-in-fact with full power to execute in our name and behalf in the
capacities indicated below any and all amendments (including post-effective
amendments and amendments thereto) to this Registration Statement and to file
the same, with all exhibits thereto and other documents in connection therewith
with the Securities and Exchange Commission and hereby ratify and confirm all
that such attorneys-in-fact, or either of them, or their substitutes shall
lawfully do or cause to be done by virtue hereof.
 
     Pursuant to the requirements of the Securities Act of 1933, this
registration statement or amendment has been signed by the following persons in
the capacities and on the date indicated above.
 
<TABLE>
<CAPTION>
                  SIGNATURE                               TITLE                      DATE
- ---------------------------------------------  ----------------------------    -----------------
<S>                                            <C>                             <C>
              /s/  BOONE PICKENS               Director and Chief Executive    January 14, 1994
             ----------------------------      Officer
                   Boone Pickens                   

              /s/  PAUL W. CAIN                Director, President and         January 14, 1994
             ----------------------------      Chief Operating Officer
                   Paul W. Cain                    

             /s/  WILLIAM D. BALLEW            Controller (Chief Accounting    January 14, 1994
             ----------------------------      Officer and acting Chief     
                  William D. Ballew            Financial Officer)           
                                                                            
</TABLE>                                       
 
                                      II-11
<PAGE>   142
 
                    REPORT OF INDEPENDENT PUBLIC ACCOUNTANTS
 
To MESA Inc.:
 
     We have audited in accordance with generally accepted auditing standards,
the consolidated financial statements of MESA Inc. included in this registration
statement and have issued our report thereon dated March 12, 1993. Our report on
the consolidated financial statements includes an explanatory paragraph that
describes the litigation discussed in Notes 2 and 9 of those statements. Our
audits were made for the purpose of forming an opinion on those statements taken
as a whole. The schedules listed in the index above are the responsibility of
MESA Inc.'s management and are presented for purposes of complying with the
Securities and Exchange Commission's rules and are not part of the basic
financial statements. These schedules have been subjected to the auditing
procedures applied in the audits of the basic financial statements and, in our
opinion, fairly state in all material respects the financial data required to be
set forth therein in relation to the basic financial statements taken as a
whole.
 
                                            ARTHUR ANDERSEN & CO.
Houston, Texas
March 12, 1993
 
                                       S-1
<PAGE>   143
 
                                                                    SCHEDULE III
                                                                     PAGE 1 OF 2
 
                                   MESA INC.
 
               CONDENSED FINANCIAL INFORMATION OF THE REGISTRANT
- --------------------------------------------------------------------------------
 
                                   MESA INC.
                       CONDENSED STATEMENTS OF OPERATIONS
                            YEARS ENDED DECEMBER 31
                                 (IN THOUSANDS)
 
<TABLE>
<CAPTION>
                                                                  1992       1991       1990
                                                                --------   --------   ---------
<S>                                                             <C>        <C>        <C>
Equity in net loss of subsidiaries............................  $(87,088)  $(72,662)  $(200,276)
Other expense.................................................    (2,144)    (6,501)         --
                                                                --------   --------   ---------
Net loss......................................................  $(89,232)  $(79,163)  $(200,276)
                                                                --------   --------   ---------
                                                                --------   --------   ---------
Net loss per common share.....................................  $  (2.31)  $  (2.05)  $   (5.19)
                                                                --------   --------   ---------
                                                                --------   --------   ---------
</TABLE>
 
           (See accompanying notes to condensed financial statements)
- --------------------------------------------------------------------------------
 
                                   MESA INC.
                            CONDENSED BALANCE SHEETS
                                  DECEMBER 31
                                 (IN THOUSANDS)
 
<TABLE>
<CAPTION>
                                                                             1992       1991
                                                                           --------   --------
<S>                                                                        <C>        <C>
Cash.....................................................................  $      1   $      1
Investment in subsidiaries...............................................   192,996    280,084
                                                                           --------   --------
                                                                           $192,997   $280,085
                                                                           --------   --------
                                                                           --------   --------
Accounts payable.........................................................  $     --   $  2,811
Intercompany payables....................................................     8,645      3,690
Stockholders' equity.....................................................   184,352    273,584
                                                                           --------   --------
                                                                           $192,997   $280,085
                                                                           --------   --------
                                                                           --------   --------
</TABLE>
 
           (See accompanying notes to condensed financial statements)
- --------------------------------------------------------------------------------
 
                                   MESA INC.
                       CONDENSED STATEMENTS OF CASH FLOWS
                            YEARS ENDED DECEMBER 31
                                 (IN THOUSANDS)
 
<TABLE>
<CAPTION>
                                                                     1992      1991      1990
                                                                    -------   -------   -------
<S>                                                                 <C>       <C>       <C>
Cash Flows from Investing Activities:
  Distributions from subsidiaries.................................  $    --   $    --   $97,190
                                                                    -------   -------   -------
                                                                         --        --    97,190
                                                                    -------   -------   -------
Cash Flows from Financing Activities:
  Distributions to equity holders.................................       --        --   (97,190)
                                                                    -------   -------   -------
                                                                         --        --   (97,190)
                                                                    -------   -------   -------
Net change in cash................................................  $    --   $    --   $    --
                                                                    -------   -------   -------
                                                                    -------   -------   -------
</TABLE>
 
           (See accompanying notes to condensed financial statements)
 
                                       S-2
<PAGE>   144
 
                                                                    SCHEDULE III
                                                                     PAGE 2 OF 2
 
                                   MESA INC.
 
                    NOTES TO CONDENSED FINANCIAL STATEMENTS
 
NOTE 1 -- GENERAL
 
     MESA Inc., a Texas corporation, was formed in 1991 in connection with a
transaction which reorganized the business of Mesa Limited Partnership from a
publicly-traded limited partnership into a corporation. The accompanying
condensed financial statements of MESA Inc. should be read in conjunction with
the consolidated financial statements of MESA Inc. and notes thereto included
elsewhere in this Registration Statement.
 
NOTE 2 -- INVESTMENT IN SUBSIDIARIES
 
     MESA Inc. conducts its business activities through direct and indirect
subsidiary partnerships. MESA Inc. owns a 95.86% limited partnership interest in
each of its direct subsidiary partnerships, Mesa Operating Limited Partnership
(MOLP), Mesa Midcontinent Limited Partnership (MMLP) and Mesa Holding Limited
Partnership (MHLP). MOLP and MMLP own 81% and 19% limited partnership interests
in Hugoton Capital Limited Partnership (HCLP), respectively. Boone Pickens,
general partner, owns a 4.14% general partner interest in each of MOLP, MMLP and
MHLP.
 
     These condensed financial statements present MESA Inc.'s investment in its
subsidiaries using the equity method of accounting whereby such investments are
recorded at historical cost adjusted for MESA Inc.'s ownership share of the
subsidiaries' cumulative results of operations.
 
NOTE 3 -- CONTINGENCIES AND GUARANTEES
 
     MESA Inc. is an obligor under the $300 million principal amount outstanding
of unsecured 12% subordinated notes due in 1996 and under the $300 million
principal amount outstanding of unsecured 13 1/2% subordinated notes due in
1999. MESA Inc. is also a guarantor of the $100 million outstanding under a $150
million revolving credit facility which is secured by MOLP's oil and gas
properties in the West Panhandle field of Texas and is due in June 1994. See
Note 4 "Long-Term Debt" to the consolidated financial statements of MESA Inc.
included elsewhere in this Registration Statement.
 
                                       S-3
<PAGE>   145
 
                                                                      SCHEDULE V
 
                                   MESA INC.
 
                         PROPERTY, PLANT AND EQUIPMENT
                     AS OF DECEMBER 31, 1992, 1991 AND 1990
- --------------------------------------------------------------------------------
 
<TABLE>
<CAPTION>
                                               BALANCE,                                BALANCE,
                                               BEGINNING     ADDITIONS,  RETIREMENTS      END
              CLASSIFICATION                   OF PERIOD     AT COST     OR SALES      OF PERIOD
- -------------------------------------------    ---------     -------     ---------     ---------
                                                                (IN THOUSANDS)
<S>                                            <C>           <C>         <C>           <C>
AS OF DECEMBER 31, 1992:
  Oil and Gas Properties, Wells and
     Equipment.............................    $1,790,224    $61,713     $    (382)    $1,851,555
  Office and Other.........................        41,861      1,392        (2,652)        40,601
                                               ----------    -------     ---------     ----------
                                               $1,832,085    $63,105     $  (3,034)    $1,892,156
                                               ----------    -------     ---------     ----------
                                               ----------    -------     ---------     ----------
AS OF DECEMBER 31, 1991:
  Oil and Gas Properties, Wells and
     Equipment.............................    $2,456,699    $31,294     $(697,769)    $1,790,224
  Office and Other.........................        55,032      2,797       (15,968)        41,861
                                               ----------    -------     ---------     ----------
                                               $2,511,731    $34,091     $(713,737)    $1,832,085
                                               ----------    -------     ---------     ----------
                                               ----------    -------     ---------     ----------
AS OF DECEMBER 31, 1990:
  Oil and Gas Properties, Wells and
     Equipment.............................    $2,456,985    $33,124     $ (33,410)    $2,456,699
  Office and Other.........................        83,455      2,053       (30,476)        55,032
                                               ----------    -------     ---------     ----------
                                               $2,540,440    $35,177     $ (63,886)    $2,511,731
                                               ----------    -------     ---------     ----------
                                               ----------    -------     ---------     ----------
</TABLE>
 
                                       S-4
<PAGE>   146
 
                                                                     SCHEDULE VI
 
                                   MESA INC.
 
                    ACCUMULATED DEPRECIATION, DEPLETION AND
                 AMORTIZATION OF PROPERTY, PLANT AND EQUIPMENT
                     AS OF DECEMBER 31, 1992, 1991 AND 1990
- --------------------------------------------------------------------------------
 
<TABLE>
<CAPTION>
                                                  BALANCE,
                                                  BEGINNING    CHARGED TO    RETIREMENTS    BALANCE, END
                 CLASSIFICATION                   OF PERIOD      INCOME       OR SALES       OF PERIOD
- ------------------------------------------------  ---------    ----------    -----------    ------------
                                                                      (IN THOUSANDS)
<S>                                               <C>           <C>           <C>             <C>
AS OF DECEMBER 31, 1992:
  Oil and Gas Properties, Wells and Equipment...  $ 481,218     $110,340      $   (1,838)     $589,720
  Office and Other..............................     20,591        3,593          (1,999)       22,185
                                                  ---------     --------      ----------      --------
                                                  $ 501,809     $113,933      $   (3,837)     $611,905
                                                  ---------     --------      ----------      --------
                                                  ---------     --------      ----------      --------
AS OF DECEMBER 31, 1991:
  Oil and Gas Properties, Wells and Equipment...  $ 678,205     $112,860      $ (309,847)     $481,218
  Office and Other..............................     23,208        5,971          (8,588)       20,591
                                                  ---------     --------      ----------      --------
                                                  $ 701,413     $118,831      $ (318,435)     $501,809
                                                  ---------     --------      ----------      --------
                                                  ---------     --------      ----------      --------
AS OF DECEMBER 31, 1990:
  Oil and Gas Properties, Wells and Equipment...  $ 456,721     $231,641(a)   $  (10,157)     $678,205
  Office and Other..............................     20,503        8,785          (6,080)       23,208
                                                  ---------     --------      ----------      --------
                                                  $ 477,224     $240,426      $  (16,237)     $701,413
                                                  ---------     --------      ----------      --------
                                                  ---------     --------      ----------      --------
</TABLE>
 
- ---------------
 
(a) Includes $75 million loss on oil and gas properties to be sold.
 
                                       S-5
<PAGE>   147
 
                                                                      SCHEDULE X
 
                                   MESA INC.
 
                   SUPPLEMENTARY INCOME STATEMENT INFORMATION
                  FOR THE THREE YEARS ENDED DECEMBER 31, 1992
                                 (IN THOUSANDS)
- --------------------------------------------------------------------------------
 
<TABLE>
<S>                                                                                  <C>
YEAR ENDED DECEMBER 31, 1992:
  Taxes --
     Production...................................................................   $ 9,380
     Ad Valorem and other.........................................................     9,251
                                                                                     -------
                                                                                     $18,631
                                                                                     -------
                                                                                     -------
YEAR ENDED DECEMBER 31, 1991:
  Taxes --
     Production...................................................................   $10,785
     Ad Valorem and other.........................................................     8,160
                                                                                     -------
                                                                                     $18,945
                                                                                     -------
                                                                                     -------
YEAR ENDED DECEMBER 31, 1990:
  Taxes --
     Production...................................................................   $17,345
     Ad Valorem and other.........................................................     7,483
                                                                                     -------
                                                                                     $24,828
                                                                                     -------
                                                                                     -------
</TABLE>
 
                                       S-6

<PAGE>   1
                                                                    EXHIBIT 3.3



                          CERTIFICATE OF INCORPORATION

                                       OF

                                MESA SUB 1, INC.


                 FIRST:  The name of the corporation is Mesa Sub 1, Inc. (the
"Corporation").

                 SECOND:  The address of the registered office of the
Corporation in the State of Delaware is 1209 Orange Street, Wilmington, County
of New Castle, Delaware 19801.  The name of the registered agent of the
Corporation at such address is The Corporation Trust Company.

                 THIRD:  The purpose of the Corporation is to engage in any
lawful act or activity for which corporations may be organized under the
General Corporation Law of the State of Delaware (the "General Corporation
Law").

                 FOURTH:  The total number of shares of stock which the
Corporation shall have the authority to issue is 1,000 shares of common stock,
par value $.01 per share ("Common Stock").

                 In the event of a voluntary or involuntary liquidation,
dissolution or winding up of the affairs of the Corporation and upon any
distribution of the assets of the Corporation in connection therewith, the
holders of Common Stock shall be entitled to receive all the assets of the
Corporation, tangible and intangible, of whatever kind available for
distribution to stockholders, ratably in proportion to the number of shares of
Common Stock held by them.

                 Each holder of Common Stock shall have one vote in respect of
each share of Common Stock held by such holder on any matter submitted to the
stockholders.  Cumulative voting of shares of Common Stock is prohibited.

                 FIFTH:  The business and affairs of the Corporation shall be
managed by or under the direction of the Board of Directors.  In furtherance
and not in limitation of the powers conferred by statute, the Board of
Directors is expressly authorized to adopt, amend or repeal the Bylaws of the
Corporation; provided, however, that the grant of such authority shall not
divest the stockholders of the power, nor limit their power to adopt, amend or
repeal the Bylaws.  The number of directors that shall constitute the whole
Board of Directors of the Corporation shall be as from time to time fixed by,
or in the manner provided in, the Bylaws of the Corporation.  The election of
directors need not be by written ballot, unless the Bylaws so provide.  In
addition to the authority and powers hereinabove or by statute conferred upon
the directors, the directors are hereby authorized and empowered to exercise
all such powers and do all such acts and things as may be exercised or done by
the Corporation, subject to the provisions of the General Corporation Law, this
Certificate of Incorporation and any Bylaws adopted by the stockholders of the
Corporation; provided, however, that no Bylaws hereafter
<PAGE>   2
adopted by the stockholders of the Corporation shall invalidate any prior act
of the directors that would have been valid if such Bylaws had not been
adopted.

                 SIXTH:  No director of the Corporation shall be personally
liable to the Corporation or any of its stockholders for monetary damages for
breach of fiduciary duty as a director involving any act or omission of any
such director; provided, however, that the foregoing provision shall not
eliminate or limit the liability of a director (a) for any breach of the
director's duty of loyalty to the Corporation or its stockholders, (b) for acts
or omissions not in good faith or which involve intentional misconduct or a
knowing violation of law, (c) under Section 174 of the General Corporation Law,
as the same exists or hereafter may be amended, or (d) for any transaction from
which the director derived an improper personal benefit.  If the General
Corporation Law is amended after the date of filing of this Certificate of
Incorporation to authorize corporate action further limiting or eliminating the
personal liability of directors, then the liability of a director of the
Corporation, in addition to the limitation on personal liability provided for
herein, shall be limited to the fullest extent permitted by the General
Corporation Law as so amended.  Any repeal or modification of this Article
Sixth by the stockholders of the Corporation shall be prospective only, and
shall not adversely affect any limitation on the personal liability of a
director of the Corporation existing at the time of such repeal or
modification.

                 SEVENTH:  The Corporation expressly elects not to be governed
by Section 203 of the General Corporation Law, as the same exists or hereafter
may be amended.

                 EIGHTH:  The name and mailing address of the sole incorporator
are as follows:

<TABLE>
<CAPTION>
                 NAME                                       MAILING ADDRESS
         <S>                                                <C>
         Brenda L. Sutherland                               Baker & Botts, L.L.P.
                                                            2001 Ross Avenue
                                                            Dallas, Texas  75201
</TABLE>

                 NINTH:  The powers of the sole incorporator shall terminate
upon the filing of this Certificate of Incorporation.  The names and mailing
addresses of the persons who are to serve as directors of the Corporation until
the first annual meeting of stockholders or until their successors are elected
and qualify are as follows:





                                      -2-
<PAGE>   3
<TABLE>
<CAPTION>
          NAME OF DIRECTOR                           MAILING ADDRESS
          <S>                                        <C>
          Boone Pickens                              c/o Mesa Sub 1, Inc.
                                                     2600 Trammell Crow Center
                                                     2001 Ross Avenue
                                                     Dallas, Texas  75201

          Paul W. Cain                               c/o Mesa Sub 1, Inc.
                                                     2600 Trammell Crow Center
                                                     2001 Ross Avenue
                                                     Dallas, Texas 75201
</TABLE>

                 IN WITNESS WHEREOF, the undersigned has executed this
Certificate of Incorporation as of December 30, 1993 in her capacity as sole
incorporator.



                                                     --------------------------
                                                     Brenda L. Sutherland





                                      -3-
<PAGE>   4

                             CERTIFICATE OF MERGER

                                       OF

                       MESA OPERATING LIMITED PARTNERSHIP

                                      INTO

                                MESA SUB 1, INC.



                 The undersigned, Mesa Sub 1, Inc., a Delaware corporation
hereby certifies as follows:

                 1.       The name and state of incorporation or jurisdiction
of formation or organization of each of the constituent entities are:
                                    
<TABLE>                             
<CAPTION>                           
Name                                             Jurisdiction
- ----                                             ------------
<S>                                              <C>
Mesa Operating Limited Partnership               Delaware
Mesa Sub 1, Inc.                                 Delaware
</TABLE>                            
                                    
                 2.       An agreement of merger has been approved, adopted,
certified, executed and acknowledged by each of the constituent entities in
accordance with the provisions of subsection (c) of Section 263 of the General
Corporation Law of the State of Delaware (the "Act") and subsection (b) of
Section 17-211 of the Delaware Revised Uniform Limited Partnership Act (the
"DRULPA").

                 3.       The surviving corporation of the merger is Mesa Sub
1, Inc., a Delaware corporation, which shall continue in existence under the
corporate name "Mesa Operating Co."

                 4.       The Certificate of Incorporation of Mesa Sub 1, Inc.,
a Delaware corporation, shall be the Certificate of Incorporation of the
surviving corporation until amended in accordance with applicable law, except
that paragraph FIRST thereof shall be amended to read in its entirety as
follows:

                 "FIRST: The name of the corporation is Mesa Operating Co. (the
                 "Corporation")."

                 5.       The executed agreement of merger is on file at the
principal place of business of Mesa Sub 1, Inc. at 2600 Trammell Crow Center,
2001 Ross Avenue, Dallas, Texas  75201.





                                      -1-
<PAGE>   5
                 6.       A copy of the agreement of merger will be furnished
by Mesa Sub 1, Inc., as the surviving entity, on request and without cost, to
any stockholder of Mesa Sub 1, Inc., or any person holding an interest in Mesa
Operating Limited Partnership.

                 7.       The merger shall become effective at 6:00 p.m.
(Eastern Standard Time) on January 5, 1994.





                                      -2-
<PAGE>   6
                 IN WITNESS WHEREOF, this Certificate of Merger has been duly
executed as of the ____ day of January, 1994, and is being filed in accordance
with Section 263 of the Act and Section 17-211 of the DRULPA.


Attest:                                 MESA SUB 1, INC.



By:                                     By:
    ---------------------                  -------------------------
    Charles L. Carpenter,                  Paul W. Cain,
    Secretary                              President





                                      -3-

<PAGE>   1
                                                                     EXHIBIT 3.4

                                     BYLAWS

                                       OF

                                MESA SUB 1, INC.



                                   ARTICLE I

                            MEETINGS OF STOCKHOLDERS


                 SECTION 1.     Place of Meetings.  All meetings of
stockholders of Mesa Sub 1, Inc. (the "Corporation") shall be held at such
place, either within or without the State of Delaware, as shall be designated
from time to time by the Board of Directors.

                 SECTION 2.     Annual Meeting.  An annual meeting of
stockholders shall be held for the election of directors on such date in each
year and at such time as shall be designated by the Board of Directors.  At
such annual meeting the stockholders shall elect by a plurality vote a Board of
Directors, and transact such other business as may properly be brought before
the meeting.  A failure to hold the annual meeting at the designated time or to
elect a sufficient number of directors to conduct the business of the
Corporation shall not affect otherwise valid corporate acts or work a
forfeiture or dissolution of the Corporation, except as may be otherwise
specifically provided by law.  If the annual meeting for election of directors
is not held on the date designated therefor, the directors shall cause the
meeting to be held as soon thereafter as convenient.  Written notice of the
annual meeting stating the place, date and hour of the meeting shall be given
not less than ten nor more than sixty days before the date of the meeting to
each stockholder entitled to vote at such meeting.  If mailed, notice is given
when deposited in the United States mail, postage prepaid, directed to the
stockholder at his address as it appears on the records of the Corporation.

                 SECTION 3.     Special Meeting.  Unless otherwise prescribed
by law or by the Certificate of Incorporation, a special meeting of the
stockholders, for any purpose or purposes, may be called by either (i) the
Chairman, if there be one, or (ii) the President,  (iii) any Vice President, if
there be one, (iv) the Secretary, or (v) any Assistant Secretary, if there be
one, and shall be called by any such officer at the request in writing of a
majority of the Board of Directors.  Any such request shall state the purpose
or purposes of the proposed meeting.  Written notice of a special meeting
stating the place, date and hour of the meeting and the purpose or purposes for
which the meeting is called shall be given not less than ten nor more than
sixty days before the date of the meeting to each stockholder entitled to vote
at such meeting.  If mailed, notice is given when deposited in the United
States mail, postage prepaid, directed to the stockholder at his address as it
appears on the records of the Corporation.
<PAGE>   2
                 SECTION 4.     Quorum and Adjournment.  Except as otherwise
provided by law, the Certificate of Incorporation or these Bylaws, the
presence, in person or represented by proxy, of the holders of a majority of
the voting power of the shares of capital stock of the Corporation entitled to
vote on any matter shall constitute a quorum for the purpose of considering
such matter at a meeting of the stockholders.  If a meeting of stockholders
cannot be organized because a quorum has not attended, the stockholders
entitled to vote thereat, present in person or represented by proxy, shall have
the power to adjourn the meeting from time to time, without notice other than
announcement at the meeting at which the adjournment is taken of the time and
place of the adjourned meeting, until a quorum shall be present or represented.
When a meeting is adjourned to another time or place, notice need not be given
of the adjourned meeting if the time and place thereof are announced at the
meeting at which the adjournment is taken.  At the adjourned meeting at which a
quorum shall be present or represented, the Corporation may transact any
business which might have been transacted at the original meeting.  If the
adjournment is for more than thirty days, or if after the adjournment a new
record date is fixed for the adjourned meeting, a notice of the adjourned
meeting shall be given to each stockholder of record entitled to vote at the
meeting.

                 SECTION 5.     Conduct of Meetings of Stockholders.  At each
meeting of the stockholders, the President, or, in his absence, a chairman
chosen by a majority vote of the stockholders present in person or represented
by proxy and entitled to vote thereat, shall preside and act as chairman of the
meeting.  The Secretary or, in his absence, an Assistant Secretary, or, in the
absence of the Secretary and all Assistant Secretaries, a person whom the
chairman of such meeting shall appoint, shall act as secretary of such meeting
and keep the minutes thereof.  The Board of Directors may adopt such rules and
regulations as it determines are reasonably necessary or appropriate in
connection with the organization and conduct of any meeting of the
stockholders.

                 SECTION 6.     Vote Required.  Except as otherwise provided by
law, the Certificate of Incorporation or these Bylaws and in all matters other
than the election of directors, the affirmative vote of the holders of a
majority of the shares present in person or represented by proxy at the meeting
and entitled to vote on the subject matter shall be the act of the
stockholders.  Directors of the Corporation shall be elected by a plurality of
the votes of the shares present in person or represented by proxy at the
meeting and entitled to vote on the election of directors.

                 SECTION 7.     Proxies.  Each stockholder entitled to vote at
a meeting of stockholders or to express consent or dissent to corporate action
in writing without a meeting may authorize another person or persons to act for
him by proxy, but no such proxy shall be voted or acted upon after three years
from its date, unless the proxy provides for a longer period.  A duly executed
proxy shall be irrevocable if it states that it is irrevocable and if, and only
as long as, it is coupled with an interest sufficient in law to support an
irrevocable power.  A proxy may be made irrevocable regardless of whether the
interest with which it is coupled is an interest in the stock itself or an
interest in the Corporation generally.





                                      -2-
<PAGE>   3
                 SECTION 8.     Stockholder List.  The officer who has charge
of the stock ledger of the Corporation shall prepare and make, at least ten
days before every meeting of stockholders, a complete list of the stockholders
entitled to vote at the meeting, arranged in alphabetical order, and showing
the address of each stockholder and the number of shares registered in the name
of each stockholder.  Such list shall be open to the examination of any
stockholder, for any purpose germane to the meeting, during ordinary business
hours, for a period of at least ten days prior to the meeting, either at a
place within the city where the meeting is to be held, which place shall be
specified in the notice of the meeting, or, if not so specified, at the place
where the meeting is to be held.  The list shall also be produced and kept open
at the time and place of the meeting during the whole time thereof, and may be
inspected by any stockholder who is present.  In lieu of making and producing
such list, the Corporation may make the information therein available by any
other means permitted by law.

                 SECTION 9.     Stock Ledger.  The stock ledger shall be the
only evidence as to who are the stockholders entitled to examine the stock
ledger, the list required by Section 8 of this Article or the books of the
Corporation, or to vote in person or by proxy at any meeting of stockholders.

                 SECTION 10.    Action by Written Consent.  Unless otherwise
provided in the Certificate of Incorporation, any action required to be taken
at any annual or special meeting of stockholders of the Corporation, or any
action which may be taken at any annual or special meeting of stockholders of
the Corporation, may be taken without a meeting, without prior notice and
without a vote, if a consent or consents in writing, setting forth the action
so taken, shall be signed by the holders of outstanding stock having not less
than the minimum number of votes that would be necessary to authorize or take
such action at a meeting at which all shares entitled to vote thereon were
present and voted and shall be delivered to the Corporation to its registered
office in the State of Delaware, its principal place of business, or an officer
or agent of the Corporation having custody of the book in which proceedings of
meetings of stockholders are recorded.  Delivery made to the Corporation's
registered office shall be by hand or by certified or registered mail, return
receipt requested.  Every written consent shall bear the date of signature of
each stockholder who signs the consent and no written consent shall be
effective to take the corporate action referred to therein unless, within sixty
days of the earliest dated consent delivered in the manner required by this
Section 10 to the Corporation, written consents signed by a sufficient number
of holders to take action are delivered to the Corporation by delivery to its
registered office in the State of Delaware, its principal place of business, or
an officer or agent of the Corporation having custody of the book in which
proceedings of meetings of stockholders are recorded.  Prompt notice of the
taking of the corporate action without a meeting by less than unanimous written
consent shall be given to those stockholders who have not consented in writing.





                                      -3-
<PAGE>   4
                                   ARTICLE II

                                   DIRECTORS

                 SECTION 1.     Board of Directors.  The business and affairs
of the Corporation shall be managed by or under the direction of the Board of
Directors.  The number of directors that shall constitute the whole Board of
Directors of the Corporation shall be fixed by the affirmative vote of a
majority of the members at any time constituting the Board of Directors, and
such number may be increased or decreased from time to time; provided, however,
that no such decrease shall have the effect of shortening the term of any
incumbent director.  Except as provided in Section 2 of this Article, directors
shall be elected by a plurality of the votes cast at the annual meetings of
stockholders, and each director so elected shall hold office until the next
annual meeting of stockholders and until his successor is duly elected and
qualified or until the earliest of his death, resignation or removal.
Directors need not be stockholders.

                 SECTION 2.     Vacancies and Newly Created Directorships.
Vacancies and newly created directorships resulting from any increase in the
authorized number of directors elected by all of the stockholders having the
right to vote as a single class may be filled by a majority of the directors
then in office, although less than a quorum, or by a sole remaining director.
Whenever the holders of any class or classes of stock or series thereof are
entitled to elect one or more directors by the Certificate of Incorporation,
vacancies and newly created directorships of such class or classes or series
may be filled by a majority of the directors elected by such class or classes
or series thereof then in office, or by a sole remaining director so elected.
If at any time, by reason of death, resignation, removal or other cause, there
are no directors in office, then an election of directors may be held in the
manner provided by the General Corporation Law of the State of Delaware (the
"General Corporation Law").  When one or more directors shall resign from the
Board, effective at a future date, a majority of the directors then in office,
including those who have so resigned, shall have power to fill such vacancy or
vacancies, the vote thereon to take effect when such resignation or
resignations shall become effective, and each director so chosen shall hold
office as provided in this Section 2 in the filling of other vacancies.

                 SECTION 3.     Removal.  Any director or the entire Board of
Directors of the Corporation may be removed, with or without cause, by the
holders of a majority of the shares then entitled to vote at the election of
directors; provided, however, that whenever the holders of any class or series
of capital stock of the Corporation are entitled to elect one or more directors
by the provisions of the Certificate of Incorporation, the provisions of this
Section 3 shall apply, in respect of the removal without cause of a director or
directors so elected, to the vote of the holders of the outstanding shares of
such class or series of capital stock and not to the vote of the outstanding
shares as a whole.

                 SECTION 4.     Resignation.  Any director of the Corporation
may resign at any time by giving written notice of his resignation to the
President or the Secretary.  Such resignation shall take effect at the date of
receipt of such notice by the President or the Secretary,





                                      -4-
<PAGE>   5
or at any later time specified therein.  Unless otherwise specified therein,
the acceptance of such resignation shall not be necessary to make it effective.

                 SECTION 5.     Compensation of Directors.  The directors shall
receive such compensation for their services as the Board of Directors may from
time to time determine.  No director shall be prevented from receiving
compensation for his services as a director by reason of the fact that he is
also an officer of the Corporation.  All directors shall be reimbursed for
their reasonable expenses of attendance at each regular or special meeting of
the Board of Directors.  Members of any committee of directors may be allowed
like compensation and reimbursement for expenses for serving as members of any
such committee and for attending committee meetings.

                 SECTION 6.     Place of Meetings.  The Board of Directors of
the Corporation may hold its meetings, both regular and special, either within
or without the State of Delaware.

                 SECTION 7.     Regular Meetings.  Promptly after each annual
election of directors, the Board of Directors shall meet for the purpose of the
election of officers and the transaction of other business, at the place where
such annual election is held. The Board of Directors may also hold other
regular meetings at such time or times and at such place or places as shall be
designated by the Board of Directors from time to time.  Notice of regular
meetings of the Board of Directors need not be given.

                 SECTION 8.     Special Meetings.  Special meetings of the
Board of Directors may be called by the President or by a majority of the Board
of Directors.  Notice shall be sent to the last known address of each director,
by mail, telegram, cable or telex, at least two days before the meeting, or
oral notice may be substituted for such written notice if received not later
than the day preceding such meeting.  Special meetings shall be called by the
President or by the Secretary in like manner and on like notice at the written
request of a majority of directors, and the place and time of such special
meeting shall be as designated in the notice of such meetings.

                 SECTION 9.     Quorum.  Except as otherwise provided by law,
the Certificate of Incorporation or these Bylaws, at all meetings of the Board
of Directors a majority of the total number of directors in office shall
constitute a quorum for the transaction of business and the vote of the
majority of the directors present at a meeting at which a quorum is present
shall be the act of the Board of Directors.  If a quorum shall not be present
at any meeting of the Board of Directors, the directors present thereat may
adjourn the meeting from time to time, without notice other than announcement
at the meeting, until a quorum shall be present.

                 SECTION 10.    Conduct of Meetings of Board of Directors.  At
each meeting of the Board of Directors the President or, in his absence, a
director chosen by a majority of the directors present, shall act as chairman
of the meeting.  The Secretary or, in his absence, a person whom the chairman
of such meeting shall appoint, shall act as secretary of such meeting and keep
the minutes thereof.





                                      -5-
<PAGE>   6
                 SECTION 11.    Meetings by Telephone Conference.  Members of
the Board of Directors of the Corporation may participate in a meeting of such
Board of Directors or committee by means of conference telephone or similar
communications equipment by means of which all persons participating in the
meeting can hear each other, and participation in a meeting pursuant to this
Section 11 shall constitute presence in person at such meeting.

                 SECTION 12.    Action by Written Consent.  Unless otherwise
restricted by the Certificate of Incorporation or these Bylaws, any action
required or permitted to be taken at any meeting of the Board of Directors or
of any committee thereof may be taken without a meeting if all members of the
Board of Directors or committee, as the case may be, consent thereto in writing
setting forth the action so taken, and the writing or writings are filed with
the minutes of proceedings of the Board of Directors or committee.

                 SECTION 13.    Committees of Directors.  The Board of
Directors may, by resolution passed by a majority of the whole Board of
Directors, designate one or more committees, each committee to consist of one
or more of the directors of the Corporation.  The Board of Directors may
designate one or more directors as alternate members of any committee, who may
replace any absent or disqualified member at any meeting of the committee.  In
the absence or disqualification of a member of a committee, the member or
members thereof present at any meeting and not disqualified from voting,
whether or not he or they constitute a quorum, may unanimously appoint another
member of the Board of Directors to act at the meeting in the place of any such
absent or disqualified member.  Any such committee, unless otherwise provided
in the resolution of the Board of Directors, shall have and may exercise all
the powers and authority of the Board of Directors in the management of the
business and affairs of the Corporation, and may authorize the seal of the
Corporation to be affixed to all papers which may require it.  Notwithstanding
the foregoing, no committee shall have the power or authority to take any of
the following actions:

                          (a)   amend the Certificate of Incorporation (except
         that a committee may, to the extent authorized in the resolution or
         resolutions providing for the issuance of shares of any series of
         capital stock of the Corporation adopted by the Board of Directors as
         permitted by the General Corporation Law, fix the designations and any
         of the preferences or rights of such shares relating to dividends,
         redemption, dissolution, any distribution of assets of the Corporation
         or the conversion into, or the exchange of such shares for, shares of
         any other class or classes or any other series of the same or any
         other class or classes of stock of the Corporation or fix the number
         of shares of any series of stock or authorize the increase or decrease
         of the shares of any series);

                          (b)   adopt an agreement of merger or consolidation
         under the General Corporation Law;

                          (c)   recommend to the stockholders the sale, lease
         or exchange of all or substantially all of the Corporation's property
         and assets;





                                      -6-
<PAGE>   7
                          (d)   recommend to the stockholders a dissolution of
        the Corporation or a revocation of a dissolution; or

                          (e)   amend the Bylaws of the Corporation.

                 In addition, unless the resolution of the Board of Directors
designating the committee expressly so provides, no such committee shall have
the power or authority to take any of the following actions:

                         (i)    declare a dividend;

                        (ii)    authorize the issuance of stock; or

                       (iii)    adopt a certificate of ownership and merger
        pursuant to the General Corporation Law.

                 Each committee shall keep regular minutes of its meetings and
report the same to the Board of Directors when required.

                 SECTION 14.    Interested Directors.  No contract or
transaction between the Corporation and one or more of its directors or
officers, or between the Corporation and any other corporation, partnership,
association, or other organization in which one or more of its directors or
officers are directors or officers, or have a financial interest, shall be void
or voidable solely for this reason, or solely because the director or officer
is present at or participates in the meeting of the Board of Directors or
committee thereof which authorizes the contract or transaction, or solely
because his or their votes are counted for such purpose if (i) the material
facts as to his or their relationship or interest and as to the contract or
transaction are disclosed or are known to the Board of Directors or the
committee, and the Board of Directors or committee in good faith authorizes the
contract or transaction by the affirmative vote of a majority of the
disinterested directors, even though the disinterested directors be less than a
quorum; or (ii) the material facts as to his or their relationship or interest
and as to the contract or transaction are disclosed or are known to the
stockholders entitled to vote thereon, and the contract or transaction is
specifically approved in good faith by vote of the stockholders; or (iii) the
contract or transaction is fair as to the Corporation as of the time it is
authorized, approved or ratified by the Board of Directors, a committee thereof
or the stockholders.  Interested directors may be counted in determining the
presence of a quorum at a meeting of the Board of Directors or of a committee
which authorizes the contract or transaction.

                                  ARTICLE III

                                    OFFICERS

                 SECTION 1.     General.  The officers of the Corporation shall
consist of a President, a Secretary and such other officers, including
assistant officers, as may be deemed





                                      -7-
<PAGE>   8
necessary by the Board of Directors.  Any number of offices may be held by the
same person, unless the Certificate of Incorporation or these Bylaws otherwise
provide.  The Board of Directors at its first meeting held after each annual
meeting of stockholders shall elect the officers of the Corporation who shall
hold their offices for such terms and shall exercise such powers and perform
such duties as shall be determined from time to time by the Board of Directors.
The Board of Directors may delegate to the President, any Vice President, the
Secretary and the Treasurer the power to appoint or remove any subordinate
officers, agents or employees.  Each officer of the Corporation shall hold his
office until his successor is elected and qualified or until the earliest of
his death, resignation or removal.

                 SECTION 2.     Removal.  Any officer may be removed, either
with or without cause, by the affirmative vote of a majority of the directors
then in office at a meeting called for that purpose, or, except in the case of
any officer elected by the Board of Directors, by any officer upon whom the
powers of removal may be conferred by the Board of Directors.

                 SECTION 3.     Resignation.  Any officer of the Corporation
may resign at any time by giving written notice of his resignation to the
Corporation.  Such resignation shall take effect at the date of receipt of such
notice by the Corporation, or at any later time specified therein.  Unless
otherwise specified therein, the acceptance of such resignation shall not be
necessary to make it effective.

                 SECTION 4.     Vacancies.  A vacancy in any office resulting
from death, resignation, removal or any other cause shall be filled for the
unexpired portion of the term in the manner prescribed in these Bylaws for
regular election or appointment to such office.

                 SECTION 5.     Officers' Salaries.  The salaries of the
officers shall be fixed from time to time by the Board of Directors, and no
officer shall be prevented from receiving a salary by reason of the fact that
he is also a director of the Corporation.

                 SECTION 6.     President.  The President shall be the chief
executive officer of the Corporation and shall in general supervise and control
all of the business and affairs of the Corporation.  He shall preside at all
meetings of the stockholders and of the Board of Directors and shall perform
such other duties as may be assigned to him from time to time by the Board of
Directors.  He may execute certificates for shares of the Corporation, any
deeds, mortgages, bonds, contracts or other instruments that the Board of
Directors has authorized to be executed, except in cases where the execution
thereof shall be expressly delegated by the Board of Directors or by these
Bylaws to some other officer or agent of the Corporation or shall be required
by law to be otherwise signed and executed.  In addition, the President shall
perform, under the direction and subject to the control of the Board of
Directors, all such other duties as are incident to the office of President and
as may be prescribed by the Board of Directors from time to time.





                                      -8-
<PAGE>   9
                 SECTION 7.     Vice President.  Each Vice President, if any,
shall perform, under the direction and subject to the control of the Board of
Directors and the President, the usual and customary duties incident to such
office (but not any unusual or extraordinary duties or powers conferred by the
Board of Directors upon the President) and such other duties as may be assigned
to him from time to time by the Board of Directors or the President.

                 SECTION 8.     Secretary and Assistant Secretary.  It shall be
the duty of the Secretary to attend all meetings of the stockholders and Board
of Directors and record correctly the proceedings held at such meetings in a
book suitable for that purpose.  It shall also be the duty of the Secretary to
attest with his signature all stock certificates issued by the Corporation, to
keep a stock ledger in which shall be correctly recorded all transactions
pertaining to the capital stock of the Corporation and to attest with his
signature all deeds, conveyances or other instruments requiring the seal of the
Corporation.  The Secretary shall have full power and authority on behalf of
the Corporation to execute any stockholders' consents and to attend and act and
to vote in person or by proxy at any meetings of the stockholders of any
corporation in which the Corporation may own stock, and at any such meetings
shall possess and may exercise any and all the rights and powers incident to
the ownership of such stock that as the owner thereof the Corporation might
have possessed and exercised if present.  The Secretary shall also perform,
under the direction and subject to the control of the Board of Directors and
the President, the usual and customary duties incident to such office and such
other duties as may be assigned to him from time to time.  The duties of the
Secretary may also be performed by any Assistant Secretary.

                 SECTION 9.     Treasurer and Assistant Treasurer.  The
Treasurer shall have the care and custody of all the funds and securities of
the Corporation that may come into his hands as Treasurer.  He may endorse
checks, drafts and other instruments for the payment of money for deposit or
collection when necessary or proper and may deposit the same to the credit of
the Corporation in such bank or banks or depositary as the Board of Directors
may designate.  In addition, he may endorse all commercial documents requiring
endorsements for or on behalf of the Corporation and may sign all receipts and
vouchers for the payments made to the Corporation.  He shall enter regularly in
the books to be kept by him for that purpose a full and accurate account of all
monies received and paid by him on account of the Corporation and shall render
an account of his transactions to the Board of Directors as often as the Board
of Directors shall require.  The Treasurer shall have full power and authority
on behalf of the Corporation to execute any stockholders' consents and to
attend and act and to vote in person or by proxy at any meetings of
stockholders of any corporation in which the Corporation may own stock, and at
any such meetings shall possess and may exercise any and all of the rights and
powers incident to the ownership of such stock that as the owner thereof the
Corporation might have possessed and exercised if present.  He shall when
requested, pursuant to a vote of the Board of Directors, give a bond to the
Corporation for the faithful performance of his duties, the expense of which
bond shall be borne by the Corporation.  The Treasurer shall also perform,
under the direction and subject to the control of the Board of Directors and
the President, the usual and customary duties incident to such office and such
other duties as may be assigned to him from time to time.  The duties of the
Treasurer may also be performed by any Assistant Treasurer.





                                      -9-
<PAGE>   10
                 SECTION 10.    Delegation of Authority.  In the case of any
absence of any officer of the Corporation or for any other reason that the
Board of Directors may deem sufficient, the Board of Directors may delegate
some or all of the powers or duties of such officer to any other officer or to
any director, employee, stockholder or agent for whatever period of time the
Board of Directors determines is necessary or appropriate.

                                   ARTICLE IV

                          STOCK AND STOCK CERTIFICATES

                 SECTION 1.     Stockholders Entitled to Certificates.  Every
holder of stock in the Corporation shall be entitled to have a certificate
representing the number of shares owned by him signed by or in the name of the
Corporation by the President or a Vice President and by the Secretary or an
Assistant Secretary of the Corporation.  Any and all the signatures on the
certificate may be a facsimile.  In case any officer, transfer agent or
registrar who has signed or whose facsimile signature has been placed upon a
certificate shall have ceased to be such officer, transfer agent or registrar
before such certificate is issued, such certificate may be issued by the
Corporation with the same effect as if such officer, transfer agent or
registrar continued to discharge said office or function at the date of
issuance.

                 SECTION 2.     Lost, Stolen or Destroyed Stock Certificates.
The Corporation may issue a new stock certificate in place of any certificate
theretofore issued by it which is alleged to have been lost, stolen or
destroyed upon the making of an affidavit of that fact by the person claiming
the certificate of stock to be lost, stolen or destroyed.  When authorizing
such issuance of a new certificate or certificates, the Board of Directors may,
in its discretion and as a condition precedent to the issuance thereof, require
that the owner of such lost, stolen or destroyed certificate or certificates,
or his legal representative, give the Corporation a bond sufficient to
indemnify the Corporation against any claim that may be made against the
Corporation on account of the alleged loss, theft or destruction of any such
certificate or the issuance of such new certificate.

                 SECTION 3.     Transfers of Stock.  Upon surrender to the
Corporation or the transfer agent or agents of the Corporation of a certificate
for shares duly endorsed or accompanied by proper evidence of succession,
assignment or authority to transfer, the Corporation shall issue a new
certificate to the person entitled thereto, cancel the certificate surrendered
to the Corporation and record the transaction upon its books.

                 SECTION 4.     Fixing Record Date.

                          (a)   Notice of Meeting; Vote. In order that the
         Corporation may determine the stockholders entitled to notice of or to
         vote at any meeting of stockholders or any adjournment thereof, the
         Board of Directors may fix a record date, which record date shall not
         precede the date upon which the resolution fixing the record date is
         adopted by the Board of Directors, and which record date shall not be
         more than sixty nor less than





                                      -10-
<PAGE>   11
         ten days before the date of such meeting.  If no record date is fixed
         by the Board of Directors, the record date for determining
         stockholders entitled to notice of or to vote at a meeting of
         stockholders shall be at the close of business on the day next
         preceding the day on which notice is given, or, if notice is waived,
         at the close of business on the day next preceding the day on which
         the meeting is held.  A determination of stockholders of record
         entitled to notice of or to vote at a meeting of stockholders shall
         apply to any adjournment of the meeting; provided, however, that the
         Board of Directors may fix a new record date for the adjourned
         meeting.


                          (b)   Written Consent.  In order that the Corporation
         may determine the stockholders entitled to consent to corporate action
         in writing without a meeting, the Board of Directors may fix a record
         date, which record date shall not precede the date upon which the
         resolution fixing the record date is adopted by the Board of
         Directors, and which date shall not be more than ten days after the
         date upon which the resolution fixing the record date is adopted by
         the Board of Directors.  If no record date has been fixed by the Board
         of Directors, the record date for determining stockholders entitled to
         consent to corporate action in writing without a meeting, when no
         prior action by the Board of Directors is required by the General
         Corporation Law, shall be the first date on which a signed written
         consent setting forth the action taken or proposed to be taken is
         delivered to the Corporation by delivery to its registered office in
         the State of Delaware, its principal place of business, or an officer
         or agent of the Corporation having custody of the book in which
         proceedings of meetings of stockholders are recorded.  Delivery made
         to the Corporation's registered office shall be by hand or by
         certified or registered mail, return receipt requested.  If no record
         date has been fixed by the Board of Directors and prior action by the
         Board of Directors is required by the General Corporation Law, the
         record date for determining stockholders entitled to consent to
         corporate action in writing without a meeting shall be at the close of
         business on the day on which the Board of Directors adopts the
         resolution taking such prior action.

                          (c)   Dividend; Distribution; Allotment of Rights.
         In order that the Corporation may determine the stockholders entitled
         to receive payment of any dividend or other distribution or allotment
         of any rights or the stockholders entitled to exercise any rights in
         respect of any change, conversion or exchange of stock, or for the
         purpose of any other lawful action, the Board of Directors may fix a
         record date, which record date shall not precede the date upon which
         the resolution fixing the record date is adopted, and which record
         date shall be not more than sixty days prior to such action.  If no
         record date is fixed, the record date for determining stockholders for
         any such purpose shall be at the close of business on the day on which
         the Board of Directors adopts the resolution relating thereto.

                 SECTION 5.     Registered Stockholders.  Except as otherwise
required by law, the Corporation shall be entitled to recognize the exclusive
right of the person registered on its books as the owner of shares to receive
dividends in respect of such shares and to vote as the owner thereof, and shall
not be bound to recognize any equitable or other claim to or interest in





                                      -11-
<PAGE>   12
such share or shares on the part of any other person, whether or not it shall
have express or other notice thereof.

                                   ARTICLE V

                                INDEMNIFICATION

                 SECTION 1.     Indemnification and Advancement of Expenses.

                          (a)   Indemnification in the Case of Proceedings
         Other Than by or in the Right of the Corporation.  The Corporation
         shall indemnify any person who was or is a party or is threatened to
         be made a party to any threatened, pending or completed action, suit
         or proceeding, whether civil, criminal, administrative or
         investigative (other than an action by or in the right of the
         Corporation) by reason of the fact that he is or was a director,
         officer, employee or agent of the Corporation, or is or was serving at
         the request of the Corporation as a director, officer, employee or
         agent of another corporation, partnership, joint venture, trust or
         other enterprise, against expenses (including attorneys' fees),
         judgments, fines and amounts paid in settlement actually and
         reasonably incurred by him in connection with such action, suit or
         proceeding if he acted in good faith and in a manner he reasonably
         believed to be in or not opposed to the best interests of the
         Corporation, and, with respect to any criminal action or proceeding,
         had no reasonable cause to believe his conduct was unlawful.  The
         termination of any action, suit or proceeding by judgment, order,
         settlement, conviction, or upon a plea of nolo contendere or its
         equivalent, shall not, of itself, create a presumption that the person
         did not act in good faith and in a manner which he reasonably believed
         to be in or not opposed to the best interests of the Corporation, and,
         with respect to any criminal action or proceeding, had reasonable
         cause to believe that his conduct was unlawful.

                          (b)   Indemnification in the Case of Proceedings By
         or in the Right of the Corporation.  The Corporation shall indemnify
         any person who was or is a party or is threatened to be made a party
         to any threatened, pending or completed action or suit by or in the
         right of the Corporation to procure a judgment in its favor by reason
         of the fact that he is or was a director, officer, employee or agent
         of the Corporation, or is or was serving at the request of the
         Corporation as a director, officer, employee or agent of another
         corporation, partnership, joint venture, trust or other enterprise
         against expenses (including attorneys' fees) actually and reasonably
         incurred by him in connection with the defense or settlement of such
         action or suit if he acted in good faith and in a manner he reasonably
         believed to be in or not opposed to the best interests of the
         Corporation and except that no indemnification shall be made in
         respect of any claim, issue or matter as to which such person shall
         have been adjudged to be liable to the Corporation unless and only to
         the extent that the Court of Chancery or the court in which such
         action or suit was brought shall determine upon application that,
         despite the adjudication of liability but in view of all the
         circumstances of the case, such person is fairly and reasonably
         entitled





                                      -12-
<PAGE>   13
         to indemnity for such expenses which the Court of Chancery or such
         other court shall deem proper.

                          (c)   Indemnification for Expenses.  To the extent
         that a director, officer, employee or agent of the Corporation has
         been successful on the merits or otherwise in defense of any action,
         suit or proceeding referred to in paragraph (a) or (b) of this Section
         1, or in defense of any claim, issue or matter therein, he shall be
         indemnified against expenses (including attorneys' fees) actually and
         reasonably incurred by him in connection therewith.

                          (d)   Determination of Entitlement to
         Indemnification.  Any indemnification under paragraph (a) or (b) of
         this Section 1 (unless ordered by a court) shall be made by the
         Corporation only as authorized in the specific case upon a
         determination that indemnification of the director, officer, employee
         or agent is proper in the circumstances because he has met the
         applicable standard of conduct set forth in paragraph (a) or (b) of
         this Section 1.  Such determination shall be made (i) by the Board of
         Directors by a majority vote of a quorum consisting of directors who
         were not parties to such action, suit or proceeding, or (ii) if such a
         quorum is not obtainable, or, even if obtainable and a quorum of
         disinterested directors so directs, by independent legal counsel in a
         written opinion, or (iii) by the stockholders.

                          (e)   Advancement of Expenses.  Expenses (including
         attorneys' fees) incurred by an officer or director in defending any
         civil, criminal, administrative or investigative action, suit or
         proceeding shall be paid by the Corporation in advance of the final
         disposition of such action, suit or proceeding upon receipt of an
         undertaking by or on behalf of such director or officer to repay such
         amount if it shall ultimately be determined that he is not entitled to
         be indemnified by the Corporation as authorized in this Article V.
         Such expenses (including attorneys' fees) incurred by other employees
         and agents may be so paid upon such terms and conditions, if any, as
         the Board of Directors deems appropriate.

                 SECTION 2.     Indemnification and Advancement not Exclusive
Right.  The indemnification and advancement of expenses provided by, or granted
pursuant to, this Article V shall not be deemed exclusive of any other rights
to which those seeking indemnification or advancement of expenses may be
entitled under any Bylaw, agreement, vote of stockholders or disinterested
directors or otherwise, both as to action in his official capacity and as to
action in another capacity while holding such office.

                 SECTION 3.     Insurance.  The Corporation shall have power to
purchase and maintain insurance on behalf of any person who is or was a
director, officer, employee or agent of the Corporation, or is or was serving
at the request of the Corporation as a director, officer, employee or agent of
another corporation, partnership, joint venture, trust or other enterprise
against any liability asserted against him and incurred by him in any such
capacity, or arising out





                                      -13-
<PAGE>   14
of his status as such, whether or not the Corporation would have the power to
indemnify him against such liability under the provisions of this Article V.

                 SECTION 4.     Certain Definitions.  For purposes of this
Article V, references to "other enterprises" shall include employee benefit
plans; references to "fines" shall include any excise taxes assessed on a
person with respect to any employee benefit plan; and references to "serving at
the request of the Corporation" shall include any service as a director,
officer, employee or agent of the Corporation which imposes duties on, or
involves services by, such director, officer, employee or agent with respect to
an employee benefit plan, its participants or beneficiaries.  In addition, for
purposes of this Article V, a person who acted in good faith and in a manner he
reasonably believed to be in the interest of the participants and beneficiaries
of an employee benefit plan shall be deemed to have acted in a manner "not
opposed to the best interests of the Corporation."

                 SECTION 5.     Continuation.  The indemnification and
advancement of expenses provided by, or granted pursuant to, this Article V
shall, unless otherwise provided when authorized or ratified, continue as to a
person who has ceased to be a director, officer, employee or agent and shall
inure to the benefit of the heirs, executors and administrators of such person.

                                   ARTICLE VI

                               GENERAL PROVISIONS

                 SECTION 1.     Amendments.  The Bylaws may be altered, amended
or repealed, in whole or in part, or new Bylaws may be adopted by the
stockholders or by the Board of Directors; provided, however, that notice of
such alteration, amendment, repeal or adoption of new Bylaws be contained in
the notice of such meeting of stockholders or Board of Directors, as the case
may be.  All such amendments must be approved by either the holders of a
majority of the outstanding capital stock entitled to vote thereon or by a
majority of the entire Board of Directors then in office.

                 SECTION 2.     Waiver of Notice.  Whenever notice is required
to be given under any provision of the General Corporation Law, the Certificate
of Incorporation or these Bylaws, a written waiver, signed by the person
entitled to notice, whether before or after the time stated therein, shall be
deemed equivalent to notice.  Attendance of a person at a meeting of
stockholders, in person or by proxy, or at a meeting of the Board of Directors
or committee thereof shall constitute a waiver of notice of such meeting,
except when the person attends such meeting for the express purpose of
objecting, at the beginning of the meeting, to the transaction of any business
because the meeting is not lawfully called or convened.  Neither the business
to be transacted at, nor the purpose of, any regular or special meeting of the
stockholders, directors, or members of a committee of directors need be
specified in any written waiver of notice unless so required by the Certificate
of Incorporation or these Bylaws.





                                      -14-
<PAGE>   15
                 SECTION 3.     Fiscal Year.  The fiscal year of the
Corporation shall end on the thirty-first day of December of each year, unless
otherwise provided by resolution of the Board of Directors.

                 SECTION 4.     Offices.  The registered office of the
Corporation in the State of Delaware shall be in care of The Corporation Trust
Company, Corporation Trust Center, 1209 Orange Street, City of Wilmington,
County of New Castle, Delaware  19801.  The Corporation may also have offices
at such other places, both within and without the State of Delaware, as the
Board of Directors may from time to time determine or the business of the
Corporation may require.





                                      -15-

<PAGE>   1

                                                                     EXHIBIT 3.5


                          CERTIFICATE OF INCORPORATION

                                       OF

                            MESA CAPITAL CORPORATION


                 I, the undersigned, for the purpose of incorporating and
organizing a corporation under the General Corporation Law of the State of
Delaware, do hereby, execute this Certificate of Incorporation and do hereby
certify as follows:

                 FIRST:   The name of the corporation is Mesa Capital
Corporation.

                 SECOND:  The address of the corporation's registered office in
the State of Delaware is 1209 Orange Street in the City of Wilmington, County
of New Castle.  The name and address of its registered agent is The Corporation
Trust Company, 1209 Orange Street, Wilmington, Delaware 19801.

                 THIRD:   The purpose of the corporation is to engage in any
lawful act or activity for which corporations may be organized under the
General Corporation Law of the State of Delaware; however, the primary purpose
of the corporation is to finance the business operations of Mesa Limited
Partnership and Mesa Operating Limited Partnership, two Delaware limited
partnerships, and any company controlled by such partnerships.

                 FOURTH:  The aggregate number of shares which the corporation
shall have authority to issue is 1,000 shares of common stock of the par value
of $1.00 each.

                 FIFTH:   Cumulative voting for the election of directors shall
not be permitted.

                 SIXTH:   The number of directors of the corporation shall be
fixed by, or in the manner provided in, the bylaws.

                 SEVENTH: The corporation may enter into contracts or
transact business with one or more of its directors or officers, or with any
corporation, firm or association in which any of its directors or officers are
shareholders, directors, officers, members, employees or otherwise interested;
and no such contract or other transaction shall be void or voidable or
otherwise affected by reason of such directorship or office in the corporation
or such interest in such other corporation, firm or association,
notwithstanding that a director or directors having such interest are present
and counted in determining the existence of a quorum at a meeting of the Board
of Directors of the corporation which acts upon or in reference to such
contract or transaction, and notwithstanding that the vote of such director or
directors shall have been necessary to authorize, approve, ratify or otherwise
obligate the corporation upon such contract or transaction, provided that the
fact
<PAGE>   2
of such interest shall be disclosed or otherwise made known to the Board of
Directors, or a majority thereof, at the meeting of the Board of Directors
which acts upon or in reference to such contract or transaction; nor shall any
director or officer be liable to account to this corporation for any profits
realized by or from or through any such transaction or contract of the
corporation by reason of such directorship, office or interest.

                 EIGHTH:  Meetings of the stockholders may be held within or
without the State of Delaware, as the bylaws of the corporation may provide.
The books and records of the corporation may be kept outside the State of
Delaware at such place or places as may be designated from time to time by the
board of directors or in the bylaws of the corporation.  The elections of
directors need not be by written ballot unless the bylaws of the corporation
shall so provide.

                 NINTH:   The Board of Directors is expressly authorized and
empowered to make, alter and repeal the bylaws of the corporation, subject to
the power of the stockholders of the corporation to alter or repeal any bylaws
made by the Board of Directors.

                 TENTH:   The corporation reserves the right at any time or
from time to time to amend, alter, change or repeal any provision contained in
this Certificate of Incorporation, and any other provision authorized by the
laws of the State of Delaware at the time in force may be added or inserted, in
the manner now or hereafter prescribed by law; and all rights, preferences and
privileges of whatsoever nature conferred upon stockholders, directors or any
other persons whomsoever by and pursuant to this Certificate of Incorporation
in its present form or as hereafter amended are granted subject to the rights
reserved in this Article.

                 ELEVENTH:  The name and mailing address of the incorporator 
of the corporation are:

<TABLE>
<CAPTION>
                 Name                             Address
                 ----                             -------
                 <S>                             <C>
                 Timothy E. McGinty              3000 One Shell Plaza
                                                 Houston, Texas 77002
</TABLE>                                      

                 IN WITNESS WHEREOF, I, the undersigned, being the incorporator
hereinbefore named, do hereby further certify that the facts hereinabove stated
are truly set forth and accordingly I have hereunto set my hand this 5th day of
June, 1986.



                                        ______________________________________
                                        Timothy E. McGinty





                                      -2-

<PAGE>   1
                                                                     EXHIBIT 3.6

                                     BYLAWS

                                       OF

                            MESA CAPITAL CORPORATION

                                   ARTICLE I.

                                 CAPITAL STOCK


                 Section 1.       Certificates Representing Shares.  The
Corporation shall deliver certificates representing all shares to which
shareholders are entitled.  Such certificates shall be signed by the President
or a Vice President and either the Secretary or any Assistant Secretary, and
shall bear the seal of the Corporation or a facsimile thereof.  The signatures
of such officers upon a certificate may be facsimiles, if the certificate is
countersigned by a transfer agent or registered by a registrar, either of which
is other than the Corporation itself or an employee of the Corporation.  In
case any officer who has signed or whose facsimile signature has been placed
upon such certificate shall have ceased to be such officer before such
certificate is issued, it may be issued by the Corporation with the same effect
as if he were such officer at the date of its issuance.

                 Section 2.       Shareholders of Record.  The Board of
Directors of the Corporation may appoint one or more transfer agents or
registrars of any class of stock of the Corporation.  Unless and until such
appointment is made, the Secretary of the Corporation shall maintain among
other records a stock certificate book, the stubs in which shall set forth the
names and addresses of the holders of all issued shares of the Corporation, the
number of shares held by each, the certificate numbers representing such
shares, the date of issue of the certificates representing such shares, and
whether or not such shares originate from original issues or from transfer.
The names and addresses of shareholders as they appear on the stock certificate
book shall be the official list of shareholders of record of the Corporation
for all purposes.  The Corporation shall be entitled to treat the holder of
record of any shares of the Corporation as the owner thereof for all purposes,
and shall not be bound to recognize any equitable or other claim to, or
interest in, such shares or any rights deriving from such shares, on the part
of any other person, including (but without limitation) a purchaser, assignee
or transferee, unless and until such other person becomes the holder of record
of such shares, whether or not the Corporation shall have either actual or
constructive notice of the interest of such other person.

                 Section 3.       Transfer of Shares.  The shares of the
Corporation shall be transferable on the stock certificate books of the
Corporation by the holder of record thereof, or his duly authorized attorney or
legal representative, upon endorsement and surrender for cancellation of the
certificates for such shares.  All certificates surrendered for





<PAGE>   2
transfer shall be cancelled, and no new certificate shall be issued until a
former certificate or certificates for a like number of shares shall have been
surrendered and cancelled, except that in the case of a lost, destroyed or
mutilated certificate, a new certificate may be issued therefor upon such
conditions for the protection of the Corporation and any transfer agent or
registrar as the Board of Directors or the Secretary may prescribe.


                                  ARTICLE II.

                            MEETINGS OF SHAREHOLDERS

                 Section 1.       Place of Meetings.  All meetings of
shareholders shall be held at the principal office of the Corporation, at One
Mesa Square, Amarillo, Texas 79189, or at such other place within or without
the State of Texas as may be designated by the Board of Directors or officer
calling the meeting.

                 Section 2.       Annual Meeting.  Annual meetings of the
shareholders shall be held during each calendar year on a date and at a time
designated by the Board of Directors.  Failure to designate a time for the
annual meeting or to hold the annual meeting at the designated time shall not
work a dissolution of the Corporation.

                 Section 3.       Special Meetings.  Special meetings of the
shareholders may be called by the President or the Board of Directors.  Special
meetings of shareholders may be called by the Secretary upon the written
request of the holders of shares entitled to cast not less than ten per cent of
all the votes entitled to be cast at such meeting.  Such request shall state
the purpose or purposes of such meeting and the matters proposed to be acted on
thereat.

                 Section 4.       Notice of Meeting.  Written notice of all
meetings stating the place, day and hour of the meeting and in the case of a
special meeting, the purpose or purposes for which the meeting is called, shall
be delivered not less than ten nor more than fifty days before the meeting to
the shareholders of record entitled to vote at such meeting.  If mailed, such
notice shall be deemed to be delivered when deposited in the United States mail
addressed to the shareholder at his address as it appears on the stock transfer
books of the Corporation, with postage thereon prepaid.

                 Section 5.       Fixing Record Date.  The Board of Directors
may fix, in advance, a date as the record date for the purpose of determining
shareholders entitled to notice of, or to vote at, any meeting of shareholders,
or shareholders entitled to receive payment of any dividend or the allotment of
any rights, or in order to make a determination of shareholders for any other
proper purpose.  Such date, in any case, shall be not more than sixty days, and
in case of a meeting of shareholders not less than ten days, prior to the date
on which the particular action requiring such determination of shareholders is
to be taken.




                                     -2-
<PAGE>   3
                 Section 6.       Voting List.  The officer or agent having
charge of the stock transfer books of the Corporation shall make, at least ten
days before each meeting of shareholders, a complete list of the shareholders
entitled to vote at such meeting or any adjournment thereof, arranged in
alphabetical order, with the address of and the number of shares held by each,
which list, for a period of ten days prior to such meeting, shall be kept on
file at the registered office of the Corporation and shall be subject to
inspection by any shareholder at any time during usual business hours.  Such
list shall also be produced and kept open at the time and place of the meeting
and shall be subject to the inspection of any shareholder during the whole time
of the meeting.  The original stock transfer books shall be prima facie
evidence as to who are the shareholders entitled to examine such list or
transfer books or to vote at any meeting of shareholders.  Failure to comply
with any requirements of this Section 6 shall not affect the validity of any
action taken at such meeting.

                 Section 7.       Voting at Meetings.  Any holder of shares of
the Corporation entitled to vote shall be entitled to one vote for each such
share, either in person or by proxy executed in writing by him or by his duly
authorized attorney in fact.  No proxy shall be valid after eleven months from
the date of its execution unless otherwise provided in the proxy.  Each proxy
shall be revocable unless expressly provided therein to be irrevocable and
unless otherwise made irrevocable by law.

                 Section 8.       Quorum of Shareholders.  The holders of a
majority of shares entitled to vote, represented in person or by proxy, shall
constitute a quorum at a meeting of shareholders, but, if a quorum is not
represented, a majority in interest of those represented may adjourn the
meeting from time to time, without notice other than announcement at the
meeting, until a quorum shall be present or represented.  At such adjourned
meeting at which a quorum shall be present or represented any business may be
transacted which might have been transacted at the meeting as originally
notified.  The vote of the holders of a majority of the shares entitled to vote
and thus represented at a meeting at which a quorum is present shall be the act
of the shareholders' meeting, unless the vote of a greater number is required
by law, the Articles of Incorporation or these bylaws.

                 Section 9.       Officers.  The President shall preside at,
and the Secretary shall keep the records of, each meeting of shareholders.  In
the absence of either such officer, his duties shall be performed by another
officer of the Corporation appointed at the meeting.


                                  ARTICLE III.

                                   DIRECTORS

                 Section 1.       Number and Tenure.  The affairs of the
Corporation shall be managed by a Board of Directors initially consisting of
one member.  Thereafter, the number of directors may be increased or decreased
from time to time by resolution of the





                                      -3-
<PAGE>   4
Board of Directors or by due election of that number of directors by the
shareholders, but no decrease by the Board of Directors shall have the effect
of shortening the term of any incumbent director.  Unless they resign or are
removed in accordance with these bylaws, members of the Board of Directors
shall hold office until the next annual meeting of shareholders and until their
successors shall have been elected and qualified.

                 Section 2.       Qualifications.  Directors need not be
shareholders of the Corporation.

                 Section 3.       Vacancies.  Any vacancy occurring in the
Board of Directors or any directorship to be filled by reason of an increase in
the number of directors may be filled by election at an annual or special
meeting of shareholders called for that purpose or by the affirmative vote of a
majority of the remaining directors, though less than a quorum of the entire
Board; provided, however, that any directorship to be filled by the Board of
Directors by reason of an increase in the number of directors may be filled for
a term of office continuing only until the next election of one or more
directors by the shareholders; and provided, further, that the Board of
Directors may not fill more than two such directorships during the period
between any two successive annual meetings of shareholders.  A director elected
to fill a vacancy shall be elected for the unexpired term of his predecessor in
office.

                 Section 4.       Place of Meeting.  Meetings of the Board of
Directors may be held either within or without the State of Texas, at whatever
place is specified by the officer calling the meeting.  In the absence of
specific designation, the meetings shall be held at the principal office of the
Corporation, in the City of Amarillo, Texas.

                 Section 5.       Regular Meetings.  The Board of Directors
shall meet each year immediately following the annual meeting of the
shareholders, at the place of such meeting, for the transaction of such
business, as may properly be brought before it.  No notice of annual meetings
need be given to either old or new members of the Board of Directors.  Regular
meetings may be held at such other times as shall be designated by the Board of
Directors.

                 Section 6.       Special Meetings.  Special meetings of the
Board of Directors may be held at any time upon the call of the President or
any director of the Corporation.  Notice shall be sent by mail or telegram to
the last known address of each director at least four days before the meeting.
Oral notice may be substituted for such written notice if given not later than
one day before the meeting.  Notice of the time, place and purpose of such
meeting may be waived in writing before or after such meeting, and shall be
equivalent to the giving of notice.  Attendance of a director at such meeting
shall also constitute a waiver of notice thereof, except where he attends for
the announced purpose of objecting to the transaction of any business on the
ground that the meeting is not lawfully called or convened.  Except as
otherwise herein provided, neither the business to be transacted at,





                                      -4-
<PAGE>   5
nor the purpose of, any regular or special meeting of the Board of Directors
need be specified in the notice or waiver of notice of such meeting.

                 Section 7.       Quorum.  A majority of the number of
directors fixed by these bylaws as from time to time amended shall constitute a
quorum for the transaction of business, but a smaller number may adjourn from
time to time until they can secure the attendance of a quorum.  The act of a
majority of the directors present at any meeting at which a quorum is present
shall be the act of the Board of Directors.  Any regular or special directors'
meeting may be adjourned from time to time by those present, whether a quorum
is present or not.

                 Section 8.       Compensation.  Directors as such shall not
receive any stated salary for their services, but by resolution of the Board a
fixed sum and expenses of attendance, if any, may be allowed for attendance at
each regular or special meeting of the Board; provided, that nothing contained
herein shall be construed to preclude any director from serving the Corporation
in any other capacity and receiving compensation therefor.

                 Section 9.       Removal.  Any director may be removed, either
for or without cause, at any special meeting of shareholders by the affirmative
vote of a majority of the outstanding shares entitled to vote at elections of
directors.  The notice calling such meeting shall give notice of the intention
to act upon such matter, and if the notice so provides, the vacancy caused by
such removal may be filled at such meeting by vote of a majority of the shares
represented at such meeting and entitled to vote for the election of directors.


                                  ARTICLE IV.

                                    OFFICERS

                 Section 1.       Officers.  The officers of the Corporation
shall be elected by the Board of Directors, and shall consist of a President, a
Vice President or Vice Presidents, a Secretary, a Treasurer, and such other
officers as the Board of Directors may from time to time designate, all of whom
shall hold office until their successors are elected and qualified.  Two or
more offices may be held by the same person, but no officer shall execute,
acknowledge or verify any instrument in more than one capacity, if such
instrument is required by law, the articles of incorporation or these bylaws to
be executed, acknowledged or verified by two or more officers.

                 The salaries of the officers shall be determined by the Board
of Directors, and may be altered by the Board of Directors from time to time
except as otherwise provided by contract.  All officers shall be entitled to be
paid or reimbursed for all costs and expenditures incurred in the Corporation's
business.





                                      -5-
<PAGE>   6
                 Section 2.       Vacancies.  Whenever any vacancies shall
occur in any office by death, resignation, increase in the number of officers
of the Corporation, or otherwise, the same shall be filled by the Board of
Directors, and the officer so elected shall hold office until his successor is
chosen and qualified.

                 Section 3.       Removal.  Any officer or agent elected or
appointed by the Board of Directors may be removed by the Board of Directors
whenever in its judgment the best interests of the Corporation will be served
thereby, but such removal shall be without prejudice to the contract rights, if
any, of the person so removed.  Election or appointment of an officer or agent
shall not of itself create contract rights.

                 Section 4.       President.  The President shall preside at
all meetings of the shareholders and, subject to the control of the Board of
Directors, shall in general supervise and control all of the business and
affairs of the Corporation.  The President may sign, with the Secretary or any
other proper officer of the Corporation thereunto authorized by the Board of
Directors, certificates for shares of the Corporation, any deeds, mortgages,
bonds, contracts or other instruments which the Board of Directors has
authorized to be executed, except in cases where the signing and execution
thereof shall be expressly delegated by the Board of Directors or by these
bylaws to some other officer or agent of the Corporation, or shall be required
by law to be otherwise signed and executed; and in general shall perform all
duties incident to the office of President and such other duties as may be
prescribed by the Board of Directors from time to time.

                 Section 5.       Vice President.  Any Vice President may
perform the usual and customary duties that pertain to such office (but no
unusual or extraordinary duties or powers conferred by the Board of Directors
upon the President) and, under the direction and subject to the control of the
Board of Directors, such other duties as may be assigned to him.

                 Section 6.       Secretary.  It shall be the duty of the
Secretary to attend all meetings of the shareholders and Board of Directors and
record correctly the proceedings had at such meetings in a book suitable for
that purpose.  It shall also be the duty of the Secretary to attest with his
signature and the seal of the Corporation all stock certificates issued by the
Corporation and to keep a stock ledger in which shall be correctly recorded all
transactions pertaining to the capital stock of the Corporation.  He shall also
attest with his signature and the seal of the Corporation all deeds,
conveyances or other instruments requiring the seal of the Corporation.  The
person holding the office of Secretary shall also perform, under the direction
and subject to the control of the Board of Directors, such other duties as may
be assigned to him.  The duties of the Secretary may also be performed by any
Assistant Secretary.

                 Section 7.       Treasurer.  The Treasurer shall keep such
moneys of the Corporation as may be entrusted to his keeping and account for
the same.  He shall be prepared at all times to give information as to the
condition of the Corporation and shall





                                      -6-
<PAGE>   7
make a detailed annual report of the entire business and financial condition of
the Corporation.  The person holding the office of Treasurer shall also
perform, under the direction and subject to the control of the Board of
Directors, such other duties as may, be assigned to him.  The duties of the
Treasurer may also be performed by any Assistant Treasurer.

                 Section 8.       Other Officers.  Assistant Secretaries, if
any, and Assistant Treasurers, if any, shall have the duties set forth in
Sections 6 and 7, respectively, of this Article IV.  Any officer whose duties
are not set forth in Sections 4 through 7 of this Article IV shall have such
duties as the Board of Directors or the President may prescribe.

                 Section 9.       Delegation of Authority.  In the case of any
absence of any officer of the Corporation or for any other reason that the
Board may deem sufficient, the Board of Directors may delegate some or all of
the powers or duties of such officer to any other officer or to any director,
employee, shareholder or agent for whatever period of time seems desirable,
providing that a majority of the entire Board concurs therein.


                                   ARTICLE V.

                            MISCELLANEOUS PROVISIONS

                 Section 1.       Indemnification of Officers and Directors.
Each person who shall have served as a director or officer of this Corporation,
or at its request as director or officer of another corporation in which it now
owns or may hereafter own shares of capital stock or of which it now is or may
hereafter be a creditor, shall be indemnified by the Corporation to the maximum
extent permitted by applicable law against expenses and costs (including
attorneys' fees) reasonably incurred by him in connection with any claim
asserted against him, by action in court or otherwise, by reason of being or
having been such director or officer.  The foregoing right of indemnification
shall not be exclusive of other rights to which he may be entitled under any
agreement, vote of shareholders or otherwise.

                 Section 2.       Amendments.  These bylaws may be altered or
repealed at any regular meeting of the shareholders or at any special meeting
of the shareholders at which a quorum is present or represented, provided
notice of the proposed alteration or repeal be contained in the notice of such
special meeting, by the affirmative vote of a majority of the shares entitled
to vote at such meeting and present or represented thereat, or by the
affirmative vote of a majority of the Board of Directors at any regular meeting
of the Board or at any special meeting of the Board if notice of the proposed
alteration or repeal be contained in the notice of such special meeting, except
that the directors shall not alter, amend or repeal any bylaw adopted by the
shareholders or enact any bylaw in conflict with a bylaw adopted by the
shareholders; provided, however, that no change of the time or place of the
meeting for the election of directors shall be made within 60 days next before
the day on which such meeting is to be held, and that in case of any change of
said time or place,





                                      -7-
<PAGE>   8
notice thereof shall be given to each shareholder in person or by letter mailed
to his last known post office address at least 20 days before the meeting is
held.

                 Section 3.       Waiver.  Whenever, under the provisions of
any law, the Articles of Incorporation or amendments thereto, or these bylaws,
any notice is required to be given to any shareholder, director or committee
member, a waiver thereof in writing signed by the person or persons entitled to
such notice, whether before or after the time stated therein, shall be
equivalent to the giving of such notice.

                 Section 4.       Conference Telephone Meetings.  Meetings of
shareholders, directors, or any committee, may be held by means of conference
telephone or similar communications equipment so long as all persons
participating in the meeting can hear each other.  Participation in a meeting
pursuant to this Section shall constitute presence in person at such meeting,
except where a person participates in the meeting for the express purpose of
objecting to the transaction of any business on the ground that the meeting is
not lawfully called or convened.

                 Section 5.       Action Without a Meeting.  Any action
required or permitted to be taken at a meeting of shareholders, directors or
any committee may be taken without a meeting if a consent in writing, setting
forth the action so taken, shall be signed by all of the shareholders,
directors or members of the committee, as the case may be, and such consent
shall have the same force and effect as a unanimous vote at a meeting.

                 Section 6.       Offices.  The principal office of the
Corporation shall be located at One Mesa Square, Amarillo, Texas 79189, unless
and until changed by resolution of the Board of Directors.  The Corporation may
also have offices at such other places as the Board of Directors may from time
to time designate, or as the business of the Corporation may require.

                 Section 7.       Resignations.  Any director or officer may
resign at any time.  Such resignations shall be made in writing and shall take
effect at the time specified therein, or, if no time be specified, at the time
of its receipt by the President or Secretary.  The acceptance of a resignation
shall not be necessary to make it effective, unless expressly so provided in
the resignation.

                 Section 8.       Seal.  The seal of the Corporation shall be
in such form as the Board of Directors shall prescribe.

                 Section 9.       Fiscal Year.  The fiscal year of the
Corporation shall end at the close of business on December 31.





                                      -8-

<PAGE>   1
                                                                     EXHIBIT 4.2

================================================================================




                           MESA CAPITAL CORPORATION,


                                   MESA INC.


                                      AND


                              MESA OPERATING CO.,
                                         ISSUERS
 



                                  $569,564,000


                         12 3/4% SECURED DISCOUNT NOTES


                               DUE JUNE 30, 1998





                          FIRST SUPPLEMENTAL INDENTURE


                          DATED AS OF JANUARY 5, 1994


                        HARRIS TRUST AND SAVINGS BANK,
                                               TRUSTEE





================================================================================
<PAGE>   2
                          FIRST SUPPLEMENTAL INDENTURE


                 THIS FIRST SUPPLEMENTAL INDENTURE, dated as of January 5,
1994, among MESA CAPITAL CORPORATION, a Delaware corporation ("Capital"), MESA
INC., a Texas corporation ("MESA"), and MESA OPERATING CO., a Delaware
corporation ("MOC" and, together with Capital and MESA, the "Issuers"), and
HARRIS TRUST AND SAVINGS BANK, a banking corporation organized and existing
under the laws of the State of Illinois, as trustee (the "Trustee").

                 Intending to be legally bound hereby, each of the parties
agrees as follows for the benefit of the other parties and for the equal and
ratable benefit of Holders of the Issuers' 12 3/4% Secured Discount Notes due
June 30, 1998 (the "Securities"):

                 WHEREAS, Capital, MESA, Mesa Operating Limited Partnership, a
Delaware limited partnership ("MOLP" and, together with MESA, the "Principal
Issuers"), and the Trustee are parties to that certain Indenture, dated as of
May 1, 1993 (the "Indenture"), pursuant to which the Securities were issued;
and

                 WHEREAS, MESA, MOLP, Mesa Sub 1, Inc. (the name of MOC prior
to the merger referred to therein) and certain other parties have entered into
a Merger Agreement, dated as of January 5, 1994, pursuant to which, among other
things, MOLP will merge with and into MOC, with MOC being the surviving entity,
and the separate existence of MOLP will cease; and

                 WHEREAS, MOC now elects to assume all of the Obligations of
MOLP arising under the Indenture and the Securities, including, without
limitation the payment of all principal of, interest on, and fees and expenses
with respect to, the Securities; and

                 WHEREAS, Section 5.02 of the Indenture provides that neither
Principal Issuer shall consolidate with, merge into or sell, lease or transfer
all or substantially all of its assets as
<PAGE>   3
an entirety to another person unless (i) the resulting, surviving or transferee
person is a corporation, partnership, or other business association or trust
organized and existing under the laws of the United States or any state thereof
or the District of Columbia, (ii) such person expressly assumes, by an
indenture supplemental to the Indenture, executed and delivered to the Trustee,
in a form satisfactory to the Trustee, all of the Obligations of such Principal
Issuer under the Indenture and the Securities, (iii) immediately before and
immediately after giving effect to such transaction, no Default or no Event of
Default shall have occurred and be continuing and (iv) if any such other person
has outstanding any Debt immediately prior to such transaction, the resulting,
surviving or transferee person shall be permitted by the terms of the
Indenture, immediately after giving effect to such transaction on a pro forma
basis, to incur at least $1.00 of additional Debt in accordance with Section
4.17(b) of the Indenture; and

                 WHEREAS, Section 5.03 of the Indenture provides that in
connection with any consolidation, merger, sale, transfer or lease contemplated
by Section 5.02 the respective Principal Issuer shall deliver, or cause to be
delivered, to the Trustee, in form and substance satisfactory to the Trustee,
an Officers' Certificate and Opinion of Counsel, each stating that such
consolidation, merger, sale, transfer or lease and the supplemental indenture
in respect thereof comply with Article Five of the Indenture and that all
conditions precedent therein provided for relating to such transaction have
been complied with; and

                 WHEREAS, Section 5.04 of the Indenture provides that upon any
consolidation or merger, or any sale, lease or transfer of all or substantially
all of the assets of either Principal Issuer, the successor person formed by
such consolidation or into which such Principal Issuer is merged or the person
to which such sale, lease or transfer is made shall succeed to, and be
substituted for, and may exercise every right and power of such Principal
Issuer under the





                                      -2-
<PAGE>   4
Indenture with the same effect as if such successor had been named as an Issuer
under the Indenture; and

                 WHEREAS, in accordance with the requirements of Section 5.02,
MOC is a corporation organized and existing under the laws of the State of
Delaware, immediately before and immediately after giving effect to the
transaction no Default and no Event of Default has occurred and is continuing,
and MOC had no Debt immediately prior to the aforementioned merger with MOLP;
and

                 WHEREAS, the Issuers have delivered to the Trustee an
Officers' Certificate and an Opinion of Counsel as specified in Section 5.03 of
the Indenture; and

                 WHEREAS, capitalized terms used herein and not otherwise
defined are used as defined in the Indenture;

                 NOW, THEREFORE, in consideration of these premises and for
other good and valuable consideration, the receipt and adequacy of which is
hereby acknowledged, Capital, MESA and MOC, as Issuers, agree as follows for
the benefit of the Trustee and the Holders of the Securities, and hereby amend
and supplement the Indenture as follows:

                 1.       In accordance with the provisions of Article Five of
the Indenture, MOC hereby assumes all of the Obligations of MOLP as an Issuer
under the Indenture and under the Securities, including without limitation, the
Issuers' obligation to pay all principal of, interest on, and fees and expenses
with respect to, the Securities, and the Issuers shall hereafter mean Capital,
MESA and MOC and the Principal Issuers shall hereafter mean MESA and MOC.

                 2.       Upon the execution and delivery of this First
Supplemental Indenture, the Indenture shall be modified to reflect the
substitution of MOC for MOLP as an Issuer under the Indenture in accordance
herewith, and this First Supplemental Indenture shall form a part of the





                                      -3-
<PAGE>   5
Indenture for all purposes, and every Holder of Securities heretofore or
hereinafter authenticated and delivered hereunder shall be bound by the
Indenture, as so modified.

                 3.       Except to the extent amended by or inconsistent with
this First Supplemental Indenture, the Company, MESA and MOC, as Issuers, and
the Trustee hereby ratify and reconfirm the Indenture in its entirety.

                 4.       This First Supplemental Indenture may be executed in
any number of counterparts, each of which so executed shall be an original, but
all such counterparts shall together constitute but one and the same
instrument.

                 5.       The Trustee shall be authorized to place on the face
or reverse side of each certificate representing the Securities the following
legend, which legend may be imprinted on the certificates or set forth thereon
by sticker, stamp or otherwise:

                 "Effective January 5, 1994, Mesa Operating Co., a Delaware
                 corporation, assumed all obligations of Mesa Operating Limited
                 Partnership under the 12 3/4% Secured Discount Notes due June
                 30, 1998 of Mesa Capital Corporation, MESA Inc. and Mesa
                 Operating Limited Partnership."

                 6.       The laws of the State of New York shall govern the
construction and interpretation of this First Supplemental Indenture, without
regard to principles of conflicts of laws.





                                      -4-
<PAGE>   6
                 IN WITNESS WHEREOF, the parties hereto executed this First
Supplemental Indenture as of the date first above written.

                                        MESA CAPITAL CORPORATION
                                       
Attest:                                
                                       
                                       
                                        By:
- ---------------------------                 ---------------------------
Charles L. Carpenter                        William D. Ballew
Secretary                                   Controller
                                       
                                       
                                        MESA INC.
                                       
Attest:                                
                                       
                                       
                                        By:
- ---------------------------                 ---------------------------
Charles L. Carpenter                        William D. Ballew
Secretary                                   Controller
                                       
                                       
                                        MESA OPERATING CO.
                                       
Attest:                                
                                       
                                       
                                       
                                        By:
- ---------------------------                 ---------------------------
Charles L. Carpenter                        William D. Ballew
Secretary                                   Controller
                                       
                                       
                                        HARRIS TRUST AND SAVINGS BANK,
                                        as Trustee
                                       
Attest:                                
                                       
                                       
                                        By:
- ---------------------------                 ---------------------------
Authorized Officer                          Assistant Vice President
                                            and Trust Officer
                                       
                                       
                                       


                                      -5-

<PAGE>   1
                                                                     EXHIBIT 4.4

================================================================================

                                      
                                      
                          MESA CAPITAL CORPORATION,
                                      
                                      
                                  MESA INC.
                                      
                                      
                                     AND
                                      
                                      
                             MESA OPERATING CO.,
                                   ISSUERS
                                      
                                      
                                      
                                      
                                 $178,932,000
                                      
                                      
                            12 3/4% DISCOUNT NOTES
                                      
                                      
                              DUE JUNE 30, 1996
                                      
                                      
                                      
                                      
                                      
                         FIRST SUPPLEMENTAL INDENTURE
                                      
                                      
                         DATED AS OF JANUARY 5, 1994
                                      
                                      
                   AMERICAN STOCK TRANSFER & TRUST COMPANY,
                                                    TRUSTEE
                                      
                                      


================================================================================
<PAGE>   2
                          FIRST SUPPLEMENTAL INDENTURE


                 THIS FIRST SUPPLEMENTAL INDENTURE, dated as of January 5,
1994, among MESA CAPITAL CORPORATION, a Delaware corporation ("Capital"), MESA
INC., a Texas corporation ("MESA"), and MESA OPERATING CO., a Delaware
corporation ("MOC" and, together with Capital and MESA, the "Issuers"), and
AMERICAN STOCK TRANSFER & TRUST COMPANY, a corporation organized and existing
under the laws of the State of New York, as trustee (the "Trustee").

                 Intending to be legally bound hereby, each of the parties
agrees as follows for the benefit of the other parties and for the equal and
ratable benefit of Holders of the Issuers' 12 3/4% Discount Notes due June 30,
1996 (the "Securities"):

                 WHEREAS, Capital, MESA, Mesa Operating Limited Partnership, a
Delaware limited partnership ("MOLP" and, together with MESA, the "Principal
Issuers"), and the Trustee are parties to that certain Indenture, dated as of
May 1, 1993 (the "Indenture"), pursuant to which the Securities were issued;
and

                 WHEREAS, MESA, MOLP, Mesa Sub 1, Inc. (the name of MOC prior
to the merger referred to therein) and certain other parties have entered into
a Merger Agreement, dated as of January 5, 1994, pursuant to which, among other
things, MOLP will merge with and into MOC, with MOC being the surviving entity,
and the separate existence of MOLP will cease; and

                 WHEREAS, MOC now elects to assume all of the Obligations of
MOLP arising under the Indenture and the Securities, including, without
limitation the payment of all principal of, interest on, and fees with respect
to, the Securities; and
<PAGE>   3
                 WHEREAS, Section 5.02 of the Indenture provides that neither
Principal Issuer shall consolidate with, merge into or sell, lease or transfer
all or substantially all of its assets as an entirety to another person unless
(i) the resulting, surviving or transferee person is a corporation,
partnership, or other business association or trust organized and existing
under the laws of the United States or any state thereof or the District of
Columbia, (ii) such person expressly assumes, by an indenture supplemental to
the Indenture, executed and delivered to the Trustee, in a form satisfactory to
the Trustee, all of the Obligations of such Principal Issuer under the
Indenture and the Securities, (iii) immediately before and immediately after
giving effect to such transaction, no Default or no Event of Default shall have
occurred and be continuing and (iv) if any such other person has outstanding
any Debt immediately prior to such transaction, the resulting, surviving or
transferee person shall be permitted by the terms of the Indenture, immediately
after giving effect to such transaction on a pro forma basis, to incur at least
$1.00 of additional Debt in accordance with Section 4.17(b) of the Indenture;
and

                 WHEREAS, Section 5.03 of the Indenture provides that in
connection with any consolidation, merger, sale, transfer or lease contemplated
by Section 5.02 the respective Principal Issuer shall deliver, or cause to be
delivered, to the Trustee, in form and substance satisfactory to the Trustee,
an Officers' Certificate and Opinion of Counsel, each stating that such
consolidation, merger, sale, transfer or lease and the supplemental indenture
in respect thereof comply with Article Five of the Indenture and that all
conditions precedent therein provided for relating to such transaction have
been complied with; and

                 WHEREAS, Section 5.04 of the Indenture provides that upon any
consolidation or merger, or any sale, lease or transfer of all or substantially
all of the assets of either Principal





                                      -2-
<PAGE>   4
Issuer, the successor person formed by such consolidation or into which such
Principal Issuer is merged or the person to which such sale, lease or transfer
is made shall succeed to, and be substituted for, and may exercise every right
and power of such Principal Issuer under the Indenture with the same effect as
if such successor had been named as an Issuer under the Indenture; and

                 WHEREAS, in accordance with the requirements of Section 5.02,
MOC is a corporation organized and existing under the laws of the State of
Delaware, immediately before and immediately after giving effect to the
transaction no Default and no Event of Default has occurred and is continuing,
and MOC had no Debt immediately prior to the aforementioned merger with MOLP;
and

                 WHEREAS, the Issuers have delivered to the Trustee an
Officers' Certificate and an Opinion of Counsel as specified in Section 5.03 of
the Indenture; and

                 WHEREAS, capitalized terms used herein and not otherwise
defined are used as defined in the Indenture;

                 NOW, THEREFORE, in consideration of these premises and for
other good and valuable consideration, the receipt and adequacy of which is
hereby acknowledged, Capital, MESA and MOC, as Issuers, agree as follows for
the benefit of the Trustee and the Holders of the Securities, and hereby amend
and supplement the Indenture as follows:

                 1.       In accordance with the provisions of Article Five of
the Indenture, MOC hereby assumes all of the Obligations of MOLP as an Issuer
under the Indenture and under the Securities, including without limitation, the
Issuers' obligation to pay all principal of, interest on,





                                      -3-
<PAGE>   5
and fees with respect to, the Securities, and the Issuers shall hereafter mean
Capital, MESA and MOC and the Principal Issuers shall hereafter mean MESA and
MOC.

                 2.       Upon the execution and delivery of this First
Supplemental Indenture, the Indenture shall be modified to reflect the
substitution of MOC for MOLP as an Issuer under the Indenture in accordance
herewith, and this First Supplemental Indenture shall form a part of the
Indenture for all purposes, and every Holder of Securities heretofore or
hereinafter authenticated and delivered hereunder shall be bound by the
Indenture, as so modified.

                 3.       Except to the extent amended by or inconsistent with
this First Supplemental Indenture, the Company, MESA and MOC, as Issuers, and
the Trustee hereby ratify and reconfirm the Indenture in its entirety.

                 4.       This First Supplemental Indenture may be executed in
any number of counterparts, each of which so executed shall be an original, but
all such counterparts shall together constitute but one and the same
instrument.

                 5.       The Trustee shall be authorized to place on the face
or reverse side of each certificate representing the Securities the following
legend, which legend may be imprinted on the certificates or set forth thereon
by sticker, stamp or otherwise:

                 "Effective January 5, 1994, Mesa Operating Co., a Delaware
                 corporation, assumed all obligations of Mesa Operating Limited
                 Partnership under the 12 3/4% Discount Notes due June 30, 1996
                 of Mesa Capital Corporation, MESA Inc. and Mesa Operating
                 Limited Partnership."





                                      -4-
<PAGE>   6
                 6.       The laws of the State of New York shall govern the
construction and interpretation of this First Supplemental Indenture, without
regard to principles of conflicts of laws.





                                      -5-
<PAGE>   7
                 IN WITNESS WHEREOF, the parties hereto executed this First
Supplemental Indenture as of the date first above written.

                                                 MESA CAPITAL CORPORATION

Attest:



                                                 By:
- -------------------------------                     --------------------------
Charles L. Carpenter                                William D. Ballew
Secretary                                           Controller


                                                 MESA INC.

Attest:


                                                 By:
- -------------------------------                     --------------------------
Charles L. Carpenter                                William D. Ballew
Secretary                                           Controller


                                                 MESA OPERATING CO.

Attest:


                                                 By:
- -------------------------------                     --------------------------
Charles L. Carpenter                                William D. Ballew
Secretary                                           Controller


                                                 AMERICAN STOCK TRANSFER & TRUST
                                                 COMPANY, as Trustee

Attest:


                                                 By:
- -------------------------------                     --------------------------
Authorized Officer                                  Assistant Vice President
                                                    and Trust Officer





                                      -6-

<PAGE>   1
                                                                    EXHIBIT 4.11

================================================================================



                       MESA CAPITAL CORPORATION, ISSUER
                                      
                                      
                                     AND
                                      
                                      
                                  MESA INC.
                                      
                                      
                                     AND
                                      
                                      
                             MESA OPERATING CO.,
                                      GUARANTORS


                                 $300,000,000
                                      
                                      
                            12% SUBORDINATED NOTES
                                      
                                      
                              DUE AUGUST 1, 1996
                                      

                              FIFTH SUPPLEMENTAL
                          COLLATERAL TRUST INDENTURE
                                      
                                      
                         DATED AS OF JANUARY 5, 1994
                                      
                                      
                  TEXAS COMMERCE BANK NATIONAL ASSOCIATION,
                                                    TRUSTEE



================================================================================
<PAGE>   2
                               FIFTH SUPPLEMENTAL
                           COLLATERAL TRUST INDENTURE


                 THIS FIFTH SUPPLEMENTAL COLLATERAL TRUST INDENTURE, dated as
of January 5, 1994, among MESA CAPITAL CORPORATION, a Delaware corporation (the
"Company"), and MESA INC., a Texas corporation ("MESA"), and MESA OPERATING
CO., a Delaware corporation ("MOC" and, together with MESA, the "Guarantor"),
and TEXAS COMMERCE BANK NATIONAL ASSOCIATION, a national banking association
organized and existing under the laws of the United States of America, as
successor trustee (the "Trustee").

                 Intending to be legally bound hereby, each of the parties
agrees as follows for the benefit of the other parties and for the equal and
ratable benefit of Holders of the Company's 12% Subordinated Notes due August
1, 1996 (the "Securities"):

                 WHEREAS, the Company, MESA, Mesa Operating Limited
Partnership, a Delaware limited partnership ("MOLP" and, together with MESA,
the "Preexisting Guarantor") and the Trustee are now parties to that certain
Collateral Trust Indenture, dated as of August 1, 1986, as amended by the
Supplemental Indenture dated as of July 31, 1987, the Second Supplemental
Collateral Trust Indenture dated as of December 31, 1991, the Third
Supplemental Collateral Trust Indenture dated as of April 30, 1992 and the
Fourth Supplemental Collateral Trust Indenture dated as of August 26, 1993 (as
amended, the "Indenture"), pursuant to which the Securities were issued; and

                 WHEREAS, MOLP, MESA, Mesa Sub 1, Inc. (the name of MOC prior
to the merger referred to therein) and certain other parties have entered into
a Merger Agreement, dated as of January 5, 1994, pursuant to which, among other
things, MOLP will merge with and into MOC, with MOC being the surviving entity,
and the separate existence of MOLP will cease; and




                                     -1-
<PAGE>   3
                 WHEREAS, MOC now elects to assume all of the Obligations of
MOLP, as one of the Preexisting Guarantors, arising under the Indenture and the
Securities and the Guaranty, including, without limitation the payment of all
principal of, interest on, and fees with respect to, the Securities; and

                 WHEREAS, Section 6.02 of the Indenture provides that the
Preexisting Guarantor shall not consolidate with, merge into or sell, lease or
transfer all or substantially all of its properties and assets as an entirety
to another person unless such person expressly assumes, by an indenture
supplemental to the Indenture, executed and delivered to the Trustee, in a form
satisfactory to the Trustee, all of the Obligations of the Original Guarantor
under the Indenture and the Securities and the Guaranty; and

                 WHEREAS, Section 6.03 of the Indenture provides that in
connection with any consolidation, merger, transfer or lease contemplated by
Section 6.02, the Preexisting Guarantor shall deliver, or cause to be
delivered, to the Trustee, in form and substance satisfactory to the Trustee,
an Officers' Certificate and an Opinion of Counsel, each stating that such
consolidation, merger, transfer or lease and the supplemental indenture in
respect thereof comply with Article Six of the Indenture and that all
conditions precedent therein provided for relating to such transaction have
been complied with; and

                 WHEREAS, Section 6.04 of the Indenture provides that upon any
consolidation or merger, or any sale, lease or transfer of all or substantially
all of the assets of the Preexisting Guarantor, the successor person formed by
such consolidation or into which the Preexisting Guarantor is merged or the
person to which such sale, lease or transfer is made shall succeed to, and be
substituted for, and may exercise every right and power of the Preexisting
Guarantor





                                      -2-
<PAGE>   4
under the Indenture with the same effect as if such successor had been named as
the Preexisting Guarantor under the Indenture and the Guaranty; and

                 WHEREAS, the Guarantor has delivered to the Trustee an
Officers' Certificate and an Opinion of Counsel as specified in Section 6.03 of
the Indenture; and

                 WHEREAS, capitalized terms used herein and not otherwise
defined have the meaning ascribed to them in the Indenture;

                 NOW, THEREFORE, in consideration of these premises and for
other good and valuable consideration, the receipt and adequacy of which is
hereby acknowledged, the Company and MESA and MOC, as Guarantor, agree as
follows for the benefit of the Trustee and the Holders of the Securities, and
hereby amend and supplement the Indenture as follows:

                 1.       In accordance with the provisions of Article Six of
the Indenture, MOC hereby assumes all of the Obligations of MOLP as Guarantor
under the Indenture and under the Securities and under the Guarantee, including
without limitation, the Company's obligation to pay all principal of, interest
on, and fees with respect to, the Securities, and the Guarantor shall hereafter
mean MESA and MOC.

                 2.       The definitions of the following terms used in the
Indenture shall be modified as set forth in this paragraph 2:

                 (a)      The definition of "Mesa Operating Limited
     Partnership" shall be amended and restated in its entirety as follows:

                 "Mesa Operating Limited Partnership" means Mesa Operating Co.,
                 a Delaware corporation, until a successor replaces it and
                 thereafter means the successor.





                                      -3-
<PAGE>   5
                 (b)      The definition of "Board of Directors" shall be
     amended and rested in its entirety as follows: 

                 "Board of Directors" means the Board of Directors of the       
                 Company or Mesa  Limited Partnership or Mesa Operating Limited
                 Partnership or any authorized committee of any such Board of
                 Directors.

                 (c)      The definition of "Officer" shall be amended and
     restated to read in its entirety as follows:

                 "Officer" means, with respect to the Company, a Guarantor or
                 any other corporation, the Chairman of the Board, the
                 President, any Vice President, the Chief Financial Officer,
                 the Treasurer, the Secretary or the Controller thereof and,
                 with respect to any general or limited partnership, the
                 general partner thereof or an Officer of a corporate general
                 partner of such partnership.

                 3.       Upon the execution and delivery of this Fifth
Supplemental Collateral Trust Indenture, the Indenture and the Guarantee shall
be modified to reflect the substitution of MOC for MOLP as a Guarantor under
the Indenture and the Guarantee in accordance herewith, and this Fifth
Supplemental Collateral Trust Indenture shall form a part of the Indenture for
all purposes, and every Holder of Securities heretofore or hereinafter
authenticated and delivered hereunder shall be bound by the Indenture, as so
modified.

                 4.       Except to the extent amended by or inconsistent with
this Fifth Supplemental Collateral Trust Collateral Trust Indenture, the
Company, MESA and MOC as Guarantor, and the Trustee hereby ratify and reconfirm
the Indenture in its entirety.





                                      -4-
<PAGE>   6
                 5.       This Fifth Supplemental Collateral Trust Indenture
may be executed in any number of counterparts, each of which so executed shall
be an original, but all such counterparts shall together constitute but one and
the same instrument.

                 6.       The Trustee shall be authorized to place on the face
or reverse side of each certificate representing the Securities the following
legend, which legend may be imprinted on the certificates or set forth thereon
by sticker, stamp or otherwise:

                 "Effective January 5, 1994, Mesa Operating Co., a Delaware
                 corporation, assumed all obligations of Mesa Operating Limited
                 Partnership under the 12% Subordinated Notes due August 1,
                 1996 of Mesa Capital Corporation, MESA Inc. and Mesa Operating
                 Limited Partnership and under the related Guaranty."

                 7.       The laws of the State of New York shall govern the
construction and interpretation of this Fifth Supplemental Indenture, without
regard to principles of conflicts of laws.





                                      -5-
<PAGE>   7
                 IN WITNESS WHEREOF, the parties hereto executed this Fifth
Supplemental Collateral Trust Indenture as of the date first above written.

                                        MESA CAPITAL CORPORATION
                                       
Attest:                                
                                       
                                       
                                        By:
- ---------------------------                ---------------------------
Charles L. Carpenter                       William D. Ballew
Secretary                                  Controller
                                       
                                       
                                        MESA INC.
                                       
Attest:                                
                                       
                                        By:
- ---------------------------                ---------------------------
Charles L. Carpenter                       William D. Ballew
Secretary                                  Controller
                                       
                                       
                                        MESA OPERATING CO.
                                       
Attest:                                
                                       
                                       
                                        By:
- ---------------------------                ---------------------------
Charles L. Carpenter                       William D. Ballew
Secretary                                  Controller
                                       
                                       
                                        TEXAS COMMERCE BANK NATIONAL
                                        ASSOCIATION, as Trustee
                                       
Attest:                                
                                       
                                       
                                        By:
- ---------------------------                ---------------------------
Authorized Officer                         Assistant Vice President
                                           and Trust Officer         
                                       
                                       
                                       
                                       
                                      -6-

<PAGE>   1
                                                                   EXHIBIT 4.16

================================================================================
                                      
                                      
                                      
                          MESA CAPITAL CORPORATION,
                                      
                                      
                                  MESA INC.
                                      
                                      
                                     AND
                                      
                                      
                             MESA OPERATING CO.,
                                         ISSUERS



                                      
                                 $300,000,000
                                      
                                      
                          13 1/2% SUBORDINATED NOTES
                                      
                                      
                               DUE MAY 1, 1999
                                      
                                      
                                      
                                      
                                      
                        FOURTH SUPPLEMENTAL INDENTURE
                                      
                                      
                         DATED AS OF JANUARY 5, 1994
                                      
                                      
                  TEXAS COMMERCE BANK NATIONAL ASSOCIATION,
                                                    TRUSTEE


================================================================================
<PAGE>   2
                         FOURTH SUPPLEMENTAL INDENTURE


                 THIS FOURTH SUPPLEMENTAL INDENTURE, dated as of January 5,
1994, among MESA CAPITAL CORPORATION, a Delaware corporation ("Capital"), MESA
INC., a Texas corporation ("MESA"), and MESA OPERATING CO., a Delaware
corporation ("MOC" and, together with Capital and MESA, the "Issuers"), and
TEXAS COMMERCE BANK NATIONAL ASSOCIATION, a national banking association
organized and existing under the laws of the United States of America, as
trustee (the "Trustee").

                 Intending to be legally bound hereby, each of the parties
agrees as follows for the benefit of the other parties and for the equal and
ratable benefit of Holders of the Issuers' 13 1/2% Subordinated Notes due May
1, 1999 (the "Securities"):

                 WHEREAS, Capital, MESA, Mesa Operating Limited Partnership, a
Delaware limited partnership ("MOLP" and, together with MESA, the
"Partnerships"), and the Trustee are parties to that certain Indenture, dated
as of May 1, 1989, as amended by the First Supplemental Indenture dated as of
December 31, 1991, the Second Supplemental Indenture dated as of April 30, 1992
and the Third Supplemental Indenture dated as of August 26, 1993 (as amended,
the "Indenture"), pursuant to which the Securities were issued; and

                 WHEREAS, MESA, MOLP, Mesa Sub 1, Inc. (the name of MOC prior
to the merger referred to therein) and certain other parties have entered into
a Merger Agreement, dated as of January 5, 1994, pursuant to which, among other
things, MOLP will merge with and into MOC, with MOC being the surviving entity,
and the separate existence of MOLP will cease; and

                 WHEREAS, MOC now elects to assume all of the Obligations of
MOLP arising under the Indenture and the Securities, including, without
limitation the payment of all principal of, interest on, and fees with respect
to, the Securities; and
<PAGE>   3
                 WHEREAS, Section 5.02 of the Indenture provides that neither
Partnership shall consolidate with, merge into or sell, lease or transfer all
or substantially all of its properties and assets as an entirety to another
person unless such person expressly assumes, by an indenture supplemental to
the Indenture, executed and delivered to the Trustee, in a form satisfactory to
the Trustee, all of the Obligations of such Partnership under the Indenture and
the Securities; and

                 WHEREAS, Section 5.03 of the Indenture provides that in
connection with any consolidation, merger, sale, transfer or lease contemplated
by Section 5.02, the respective Partnership shall deliver, or cause to be
delivered, to the Trustee, in form and substance satisfactory to the Trustee,
an Officers' Certificate and an Opinion of Counsel, each stating that such
consolidation, merger, sale, transfer or lease and the supplemental indenture
in respect thereof comply with Article Five of the Indenture and that all
conditions precedent therein provided for relating to such transaction have
been complied with; and

                 WHEREAS, Section 5.04 of the Indenture provides that upon any
consolidation or merger, or any sale, lease or transfer of all or substantially
all of the assets of either Partnership, the successor person formed by such
consolidation or into which such Partnership is merged or the person to which
such sale, lease or transfer is made shall succeed to, and be substituted for,
and may exercise every right and power of such Partnership under the Indenture
with the same effect as if such successor had been named as an Issuer under the
Indenture; and

                 WHEREAS, the Issuers have delivered to the Trustee an
Officers' Certificate and an Opinion of Counsel as specified in Section 5.03 of
the Indenture; and

                 WHEREAS, capitalized terms used herein and not otherwise
defined are used as defined in the Indenture;





                                      -2-
<PAGE>   4
                 NOW, THEREFORE, in consideration of these premises and for
other good and valuable consideration, the receipt and adequacy of which is
hereby acknowledged, Capital, MESA and MOC, as Issuers, agree as follows for
the benefit of the Trustee and the Holders of the Securities, and hereby amend
and supplement the Indenture as follows:

                 1.       In accordance with the provisions of Article Five of
the Indenture, MOC hereby assumes all of the Obligations of MOLP as an Issuer
under the Indenture and under the Securities, including without limitation, the
Issuers' obligation to pay all principal of, interest on, and fees with respect
to, the Securities, and the Issuers shall hereafter mean Capital, MESA and MOC
and the Partnerships shall hereafter mean MESA and MOC.

                 2.       The definitions of the following terms used in the
                          Indenture shall be modified as set forth in this
                          paragraph 2:

                 (a)      The definition of "Operating" shall be amended and
     restated in its entirety as follows:

                 "Operating" means Mesa Operating Co., a Delaware corporation,
                 until a successor replaces it and thereafter means the
                 successor.

                 (b)      The definition of "Board of Directors" shall be
     amended and rested in its entirety as follows:

                 "Board of Directors" means the Board of Directors of Capital
                 or MLP or Operating or any authorized committee of any such
                 Board of Directors.

                 (c)      The definition of "Officer" shall be amended and
     restated to read in its entirety as follows:





                                      -3-
<PAGE>   5
                 "Officer" means, with respect to Capital, MLP, Operating or
                 any other corporation, the Chairman of the Board, the
                 President, any Vice President, the Chief Financial Officer,
                 the Treasurer, the Secretary or the Controller thereof and,
                 with respect to any general or limited partnership, the
                 general partner thereof or an Officer of a corporate general
                 partner of such partnership.

                 (d)      The definition of "Officers' Certificate" shall be
         amended by deleting the words "or of a corporate general partner of
         either Partnership" therefrom.

                 3.       Upon the execution and delivery of this Fourth
Supplemental Indenture, the Indenture shall be modified to reflect the
substitution of MOC for MOLP as an Issuer under the Indenture in accordance
herewith, and this Fourth Supplemental Indenture shall form a part of the
Indenture for all purposes, and every Holder of Securities heretofore or
hereinafter authenticated and delivered hereunder shall be bound by the
Indenture, as so modified.

                 4.       Except to the extent amended by or inconsistent with
this Fourth Supplemental Indenture, Capital, MESA and MOC, as Issuers, and the
Trustee hereby ratify and reconfirm the Indenture in its entirety.

                 5.       This Fourth Supplemental Indenture may be executed in
any number of counterparts, each of which so executed shall be an original, but
all such counterparts shall together constitute but one and the same
instrument.

                 6.       The Trustee shall be authorized to place on the face
or reverse side of each certificate representing the Securities the following
legend, which legend may be imprinted on the certificates or set forth thereon
by sticker, stamp or otherwise:





                                      -4-
<PAGE>   6
                 "Effective January 5, 1994, Mesa Operating Co., a Delaware
                 corporation, assumed all obligations of Mesa Operating Limited
                 Partnership under the 13 1/2% Subordinated Notes due May 1,
                 1999 of Mesa Capital Corporation, MESA Inc. and Mesa Operating
                 Limited Partnership."

                 7.       The laws of the State of New York shall govern the
construction and interpretation of this Fourth Supplement Indenture, without
regard to principles of conflicts of laws.





                                      -5-
<PAGE>   7
                 IN WITNESS WHEREOF, the parties hereto executed this Fourth
Supplemental Indenture as of the date first above written.

                                        MESA CAPITAL CORPORATION
                                       
Attest:                                
                                       
                                       
                                        By:
- ---------------------------                ---------------------------
Charles L. Carpenter                       William D. Ballew
Secretary                                  Controller
                                       
                                       
                                        MESA INC.
                                       
Attest:                                
                                       
                                       
                                        By:
- ---------------------------                ---------------------------
Charles L. Carpenter                       William D. Ballew
Secretary                                  Controller
                                       
                                       
                                        MESA OPERATING CO.
                                       
Attest:                                
                                       
                                       
                                        By:
- ---------------------------                ---------------------------
Charles L. Carpenter                       William D. Ballew
Secretary                                  Controller
                                       
                                       
                                        TEXAS COMMERCE BANK NATIONAL
                                        ASSOCIATION, as Trustee
                                       
Attest:                                
                                       
                                       
                                        By:
- ---------------------------                ---------------------------
Authorized Officer                         Assistant Vice President
                                           and Trust Officer
                                       
                                       
                                       
                                       
                                       
                                      -6-

<PAGE>   1





                                                                   EXHIBIT 4.21



                      ASSIGNMENT AND ASSUMPTION AGREEMENT


         This Assignment and Assumption Agreement dated as of January 5, 1994
("Agreement") is among Mesa Operating Limited Partnership, a Delaware limited
partnership ("Borrower"), Mesa Operating Co., a Delaware corporation ("MOC"),
Mesa Inc., a Texas corporation ("Mesa"), the banks named in the Credit
Agreement described below ("Banks"), and Societe Generale, Southwest Agency, as
agent for the Banks ("Agent").

                                  INTRODUCTION

         A.      The Borrower is a party to (1) the Second Amended and Restated
Credit Agreement dated as of May 1, 1993 ("Credit Agreement," the defined terms
of which are used in this Agreement unless otherwise defined herein) among the
Borrower, Mesa, the Banks and the Agent and (2) the other Credit Documents
listed on the attached Schedule 1 (together with the Credit Agreement, the
"Current Credit Documents").

         B.      Mesa is a party to the Credit Agreement and pursuant to
Section 2.14 thereof has agreed to be jointly and severally liable for the
Borrower's obligations under the Credit Agreement and the other Credit
Documents.

         C.      The Borrower intends to merge with and into MOC pursuant to
the terms of the Agreement of Merger dated as of January 5, 1994 ("Agreement of
Merger") among the Borrower, Mesa, Sub 1, Inc., a Delaware corporation ("Sub
1"), Mesa Midcontinent Limited Partnership, a Delaware limited partnership,
Mesa Holding Limited Partnership, a Delaware limited partnership, Mesa
Environmental Ventures Limited Partnership, a Delaware limited partnership,
Mesa Environmental Co., a Texas corporation, Mesa Sub 2, Inc., a Delaware
corporation, Mesa Sub 3, Inc., a Delaware corporation, Mesa Sub 4, Inc., a
Delaware corporation, Pickens Operating Co., a Texas corporation and Boone
Pickens (such transaction being referred to as the "Merger").  Sub 1 will be
the surviving entity in the Merger and, simultaneously with the Merger, Sub 1
will change its name to Mesa Operating Co. (which entity is referred to herein
as MOC).

         D.      The Banks have agreed to consent to the Merger documentation
represented hereby on the conditions that (1) MOC agrees to assume the
obligations of the Borrower under the Credit Documents (including the Current
Credit Documents) and (2) Mesa reaffirms its obligations under the Credit
Agreement and the other Credit Documents to which it is a party, in each case
pursuant to the terms of this Agreement.

         THEREFORE, the Borrower, MOC, Mesa, the Agent and the Banks agree as
follows:

         Section 1. Assumption of Liability.  Upon the effectiveness of this
Agreement, the Borrower assigns to MOC, and MOC assumes and agrees to be
primarily liable for the repayment of, all of the Borrower's obligations now or
hereafter arising under, or in connection
<PAGE>   2
with, the Credit Agreement and the other Credit Documents (as defined in the
Credit Agreement) (collectively, the "Obligations").  MOC's obligations under
the Credit Documents, including its obligation to repay the Obligations shall
apply to and cover all renewals, extensions, and refinancings of the Credit
Agreement and the other Credit Documents or the Obligations thereunder.
Additionally, MOC agrees to be substituted for the Borrower under, and become a
party to, the Credit Agreement and each other Credit Document to which the
Borrower was a party upon the effectiveness of this Agreement.  In addition,
all representations and covenants referring to the Borrower's existence as a
limited partnership shall be modified to refer to MOC's existence as a
corporation.

         Section 2. Reaffirmation of Liability.  Mesa hereby reaffirms its
obligations under the Credit Agreement and each of the other Credit Documents
to which it is a party and agrees to remain liable for the repayment of the
Obligations.  Without limiting the foregoing sentence, Mesa's obligations under
the Credit Agreement and such other Credit Documents shall continue to be
enforceable against it notwithstanding the Merger or the assumption of
liabilities by MOC pursuant to Section 1.

         Section 3. Consents.  Subject to the fulfillment of the conditions
precedent set forth in Section 6 below, (a) the Agent and the Banks consent to
the execution of the Agreement of Merger and (b) MOC acknowledges and consents
to the terms of the Intercreditor Agreement dated as of May 1, 1993 among the
Agent, Harris Trust and Savings Bank, as trustee under the Secured Indenture,
and American Stock Transfer & Trust Company, as trustee under the Convertible
Indenture and the Unsecured Indenture.

         Section 4. Representations and Warranties.  Each of the Borrower, MOC,
and Mesa represents and warrants to the Agent and the Banks that:

                 (a)      it is a corporation or limited partnership, as
applicable, duly and validly organized and existing in the state of its
formation, and is authorized to do business and is in good standing in all
jurisdictions in which such qualification or authorization is necessary;

                 (b)      after giving effect to the Merger and this Agreement,
(i) except as set forth on Schedule 2 attached hereto, all the representations
and warranties set forth in the Credit Documents are true and correct in all
material respects as of the date of this Agreement and (ii) no Default or Event
of Default has occurred and is continuing;

                 (c)      (i) the execution, delivery and performance of this
Agreement are within its corporate or partnership, as applicable, power and
authority and have been duly authorized by appropriate actions and (ii) this
Agreement constitutes a legal, valid, and binding obligation of such entity
enforceable in accordance with its terms, except as limited by applicable
bankruptcy, insolvency, reorganization, moratorium, or similar laws affecting
the rights of creditors generally and general principles of equity; and





                                     -2-
<PAGE>   3
                 (d)      no Default or Event of Default has occurred or is
continuing as a result of the Merger.

         Section 5. Event of Default.  If any representation or warranty in
this Agreement shall be untrue or incorrect in any material respect or if the
covenant set forth in Section 7 below is breached, an Event of Default under
each of the Credit Documents shall be deemed to have occurred and each of the
Agent and the Banks may exercise any remedies it may have after the occurrence
of an Event of Default under such Credit Documents.

         Section 6. Effectiveness.  This Agreement shall become effective, MOC
shall be a party to the Credit Documents and assume the Obligations, and Mesa
shall reaffirm its obligations under the Credit Agreement and the other Credit
Documents to which it is a party, upon the occurrence of the following
conditions precedent:

                 (a)      the Agent shall have received duly and validly
executed originals of (i) this Agreement, (ii) the Agreement of Merger, (iii)
the Second Amended and Restated Pledge Agreement dated as of January 5, 1994
between Mesa and the Agent, (iv) UCC-1 and UCC-3 Financing Statements executed
by MOC, (v) an opinion of MOC's counsel, (vi) a certificate of an officer of
MOC certifying its charter documents and resolutions of its Board of Directors
authorizing its obligations under this Agreement, the Credit Agreement, the
other Credit Documents, and the Agreement of Merger, and (vii) such other
documents as the Agent may reasonably request, each in form and substance
satisfactory to the Agent;

                 (b)      the representations and warranties in this Agreement
shall be true and correct in all material respects; and

                 (c)      the Merger shall have become effective under Delaware
law.

         Section 7. Covenant.  MOC shall (a) continue to comply with the
requirements of Section 5.7 of the Mortgage, (b) no later than February 1, 1994
execute and deliver to the Agent replacement Reserve Transfer Orders (as
defined in the Mortgage) addressed to CIG and each other Product Purchaser (as
such terms are defined in the Mortgage) in form and substance satisfactory to
the Agent and (c) deliver to the Agent no later than February 1, 1994 copies of
all consents, notices or filings (i) required by the terms of the B Contract
and the other contracts on Schedule 1 to the Credit Agreement, the Supply
Contract, and any other material contracts existing in connection with the
operation of the Borrower's or MOC's business and (ii) executed by the
Borrower, MOC, or Mesa in connection with the Merger with respect to the
foregoing contracts.

         Section 8. Successors and Assigns.  This Agreement shall inure to the
benefit of the Agent, the Banks, and their respective successors, legal
representatives and assigns and shall be binding upon the Borrower, MOC, and
Mesa and their successors, legal representatives and assigns; provided that,
except as permitted under the terms of the Credit Agreement, none of the





                                      -3-
<PAGE>   4
Borrower, MOC, or Mesa may assign their rights or delegate their duties under
this Agreement or any other Credit Document without the prior written consent
of the Agent and the Banks.

         Section 9. Choice of Law.  This Agreement shall be governed by and
construed and enforced in accordance with the laws of the State of Texas.
Pursuant to Article 15.10(b) of Chapter 15 ("Chapter 15") of the Texas Credit
Code, the parties hereto expressly agree that Chapter 15 shall not apply to
this Agreement or to any loan, nor shall this Agreement or any loan be governed
by or be subject to the provisions of Chapter 15 in any manner whatsoever.

         Section 10. Counterparts.  This Agreement may be signed in any number
of counterparts, each of which shall be an original.

         PURSUANT TO SECTION 26.02 OF THE TEXAS BUSINESS AND COMMERCE CODE, A
CREDIT AGREEMENT IN WHICH THE AMOUNT INVOLVED IN THE CREDIT AGREEMENT EXCEEDS
$50,000 IN VALUE IS NOT ENFORCEABLE UNLESS THE CREDIT AGREEMENT IS IN WRITING
AND SIGNED BY THE PARTY TO BE BOUND OR THAT PARTY'S AUTHORIZED REPRESENTATIVE.

         THE RIGHTS AND OBLIGATIONS OF THE PARTIES TO AN AGREEMENT SUBJECT TO
THE PRECEDING PARAGRAPH SHALL BE DETERMINED SOLELY FROM THE WRITTEN CREDIT
AGREEMENT, AND ANY PRIOR ORAL AGREEMENTS BETWEEN THE PARTIES ARE SUPERSEDED BY
AND MERGED INTO THE CREDIT AGREEMENT.  THIS WRITTEN AGREEMENT AND THE    CREDIT
DOCUMENTS, AS DEFINED IN THIS AGREEMENT, REPRESENT THE FINAL AGREEMENT AMONG
THE PARTIES AND MAY NOT BE CONTRADICTED BY EVIDENCE OF PRIOR, CONTEMPORANEOUS,
OR SUBSEQUENT ORAL AGREEMENTS OF THE PARTIES.

         THERE ARE NO UNWRITTEN ORAL AGREEMENTS BETWEEN THE PARTIES.





                                      -4-
<PAGE>   5
         EXECUTED as of the 5th day of January, 1994

                                        MESA OPERATING LIMITED PARTNERSHIP

                                        By: Pickens Operating Co., its
                                            General Partner


                                        By:_____________________________________
                                            Paul W. Cain
                                            President


                                        MESA INC.


                                        By:_____________________________________
                                            Paul W. Cain
                                            President


                                        MESA OPERATING CO.


                                        By:_____________________________________
                                            Paul W. Cain
                                            President


                                        SOCIETE GENERALE,
                                        SOUTHWEST AGENCY, as Agent
                                         for the Banks


                                        By:____________________________________
                                            Name:______________________________
                                            Title:_____________________________





                                      -5-
<PAGE>   6
                                       SOCIETE GENERALE,
                                        SOUTHWEST AGENCY


                                       By:_____________________________________
                                           Name:_______________________________
                                           Title:______________________________


                                       BANQUE INDOSUEZ


                                       By:_____________________________________
                                           Name:_______________________________
                                           Title:______________________________





                                      -6-
<PAGE>   7
STATE  OF  TEXAS          )
                          )
COUNTY OF DALLAS          )

         This instrument was acknowledged before me on January __, 1994 by Paul
W. Cain, President of Pickens Operating Co., a Texas corporation, on behalf of
said corporation as general partner on behalf of Mesa Operating Limited
Partnership, a Delaware limited partnership.


                                       _________________________________________
                                       Notary Public in and for
                                       The State of ____________________________
                                       Name: ___________________________________
                                       My Commission Expires: __________________


STATE  OF  TEXAS          )
                          )
COUNTY OF DALLAS          )

         This instrument was acknowledged before me on January __, 1994 by Paul
W. Cain, President of Mesa Inc., a Texas corporation, on behalf of said
corporation.

                                       _________________________________________
                                       Notary Public in and for
                                       The State of ____________________________
                                       Name: ___________________________________
                                       My Commission Expires: __________________





                                      -7-
<PAGE>   8
STATE  OF  TEXAS          )
                          )
COUNTY OF DALLAS          )

         This instrument was acknowledged before me on January __, 1994 by Paul
W. Cain, President of Mesa Operating Co., a Delaware corporation, on behalf of
said corporation.



                                       _________________________________________
                                       Notary Public in and for
                                       The State of ____________________________
                                       Name: ___________________________________
                                       My Commission Expires: __________________


STATE  OF  TEXAS          )
                          )
COUNTY OF DALLAS          )

         This instrument was acknowledged before me on January __, 1994 by
___________________, ________________ of Societe Generale, a French banking
corporation acting herein through its Southwest Agency, on behalf of said
corporation, as agent.



                                       _________________________________________
                                       Notary Public in and for
                                       The State of ____________________________
                                       Name: ___________________________________
                                       My Commission Expires: __________________





                                      -8-
<PAGE>   9
STATE  OF  TEXAS          )
                          )
COUNTY OF DALLAS          )

         This instrument was acknowledged before me on __________, 1993 by
___________________, ________________ of Societe Generale, a French banking
corporation acting herein through its Southwest Agency, on behalf of said
corporation.


                                       _________________________________________
                                       Notary Public in and for
                                       The State of ____________________________
                                       Name: ___________________________________
                                       My Commission Expires: __________________



STATE  OF  TEXAS          )
                          )
COUNTY OF HARRIS          )

         This instrument was acknowledged before me on __________, 1993 by
___________________, ________________ of Banque Indosuez, a ______________, on
behalf of said corporation.


                                       _________________________________________
                                       Notary Public in and for
                                       The State of ____________________________
                                       Name: ___________________________________
                                       My Commission Expires: __________________





                                      -9-
<PAGE>   10
                                   SCHEDULE 1


1.       Promissory Note in the amount of $78,000,000 dated as of May 1, 1993,
         executed by the Borrower and Mesa and payable to Societe Generale.

2.       Promissory Note in the amount of $12,000,000 dated as of May 1, 1993,
         executed by the Borrower and Mesa and payable to Banque Indosuez.

3.       Deed of Trust, Assignment of Production, Security Agreement and
         Financing Statement dated as of June 3, 1991 executed by the Borrower
         to Mark C. Evans, Trustee, for the benefit of the Agent and recorded
         in the places listed on Exhibit A-1 attached hereto.

4.       First Amendment to Deed of Trust, Assignment of Production, Security
         Agreement and Financing Statement dated as of December 31, 1991
         executed by the Borrower and the Agent and recorded in the places
         listed on Exhibit A-2 attached hereto.

5.       Second Amendment to Deed of Trust, Assignment of Production, Security
         Agreement and Financing Statement dated as of May 1, 1993, executed by
         the Borrower and the Agent and recorded in the places listed on
         Exhibit A-3 attached hereto.

6.       Pledge Agreement dated as of May 1, 1993, between the Borrower and the
         Agent.

7.       UCC-1 Financing Statement executed by the Borrower and filed with the
         Texas Secretary of State.

8.       Deposit Account Agreement dated as of May 1, 1993 between the Borrower
         and the Agent.

9.       Letters to Purchasers dated August 26, 1991, executed by the Agent and
         the Borrower.

10.      Letter to Societe Generale from the Borrower dated August 26, 1993.

11.      Lockbox Assignment and Consent dated as of August 26, 1993 executed by
         Borrower, the Agent and Texas Commerce Bank National Association.

12.      Letter Agreement dated August 26, 1993 among the Agent, the Borrower
         and Texas Commerce Bank, National Association.

<PAGE>   1

                                                                   EXHIBIT 10.24


                         AMENDMENT TO "B" CONTRACT AND
                        PRODUCTION ALLOCATION AGREEMENT

         This Agreement is entered into and effective as of the first day of
January, 1993, by and between Colorado Interstate Gas Company ("CIG") and Mesa
Operating Limited Partnership ("MESA").  CIG and MESA may be referred to herein
individually as a "Party" or collectively as the "Parties," and this Agreement
may be referred to herein as the "Amendment."

         WHEREAS, CIG and MESA are parties to that certain contract dated
January 3, 1928, as amended and supplemented (""B" Contract"), and that certain
"B" Contract Production Allocation Agreement, dated January 1, 1991 ("PAA"),
which amended the "B" Contract to the extent expressly provided for therein.

         WHEREAS, the parties desire to make certain amendments to the "B"
Contract and the PAA, as more fully set forth herein.

         NOW, THEREFORE, for and in consideration of the covenants and
obligations set forth herein, and other good and valuable consideration, the
sufficiency and receipt of which is hereby acknowledged, CIG and MESA hereby
agree as follows:

         1.      Each of the terms used herein shall have the same meaning as
set forth in the PAA, unless otherwise specifically defined herein.

         2.      The phrase "Section 3.1 hereof" in Section 1.30 of the PAA is
deleted and replaced with the phrase "Section 3.1.a."

         3.      Section 1.33 of the PAA shall be deleted in its entirety and
the following substituted therefor:

                 1.33     "Redetermination Date" shall mean the first day of
                 any month following at least ninety (90) days prior written
                 notice of either Party's desire to redetermine the Net "B"
                 Contract Production from and after January 1, 1991 through
                 Depletion.

         4.      New Sections 1.35 through 1.42 of the PAA are added as follows:

                 1.35     "Summer Months" shall mean the months of April
                 through October.

                 1.36     "Winter Months" shall mean months other than Summer
                 Months.

                 1.37     "Plant Inlet Field Fuel" means those volumes of Gross
                 "B" Contract Production delivered to the inlet(s) of the
                 Bivins Plant, Fritch Plant and/or the Fain Plant which, after
                 processing, yield those volumes of residue gas used as Net "B"
                 Contract Field Fuel.
<PAGE>   2
                 1.38     "PYPIFF" means the Plant Inlet Field Fuel for the
                 calendar year prior to the current year.

                 1.39     "Fuel Difference" or "FD," with respect to a
                 determination made for the current calendar year, equals the
                 PYPIFF minus the Plant Inlet Field Fuel for the second
                 preceding calendar year.  FD for the calculation of CIG's
                 calendar year 1997 Net "B" Contract entitlement shall be
                 deemed 0.  The calculation of the Fuel Difference shall be
                 adjusted as necessary to reflect the outcome of the Field Fuel
                 issue set forth in Article IV of this Agreement.

                 1.40     "Exchange Volumes" shall mean those volumes as
                 defined in Section 3.1.b(2)(e) below.

                 1.41     "Exchange Percentage" shall mean 17.25% if CIG is an
                 Overproduced Party; 42.25% if CIG is an Underproduced Party;
                 or 23% if CIG is neither an Overproduced Party nor an
                 Underproduced Party.

                 1.42     "Gas Processing Agreement" means that Gas Processing
                 Agreement between CIG and MESA dated as of January 1, 1993.

         5.      Section 3.1.a. of the PAA is deleted in its entirety and the
following substituted therefor:

                 a.       Notwithstanding anything else in this Agreement to
                          the contrary, MESA shall be entitled to 77% of the
                          Net "B" Contract Production from and after January 1,
                          1991 through Depletion, and CIG shall be entitled to
                          23% of the Net "B" Contract Production from and after
                          January 1, 1991 through Depletion.

         6.      Section 3.1.b. of the PAA is deleted in its entirety and the
following substituted therefor:

                 3.1.b.(1)        During the period from January 1, 1991,
                                  through December 31, 1996, each Party shall
                                  be entitled to take, on a daily basis, its
                                  respective Percentage Share of Net "B"
                                  Contract Production subject to the provisions
                                  of Section 3.4 below and to the following:

                          (a)     During calendar year 1993, MESA's takes of
                                  Net "B" Contract Production shall be limited
                                  to a maximum of 35 Bcf.

                          (b)     During the period from January 1, 1994,
                                  through December 31, 1996, MESA's takes of
                                  Net "B" Contract Production shall be limited
                                  to a maximum of 32 Bcf per calendar year.





                                      -2-
<PAGE>   3
                 3.1.b.(2)        During the period from January 1, 1997,
                                  through December 31, 1999, and subject to the
                                  provisions of Section 3.4 below:

                          (a)     During the Summer Months and subject to 
                                  Section 3.1.b(2)(d) below:

                                  (i)      CIG shall be entitled to take, on a
                                  daily basis, the volume resulting from the
                                  formula 40 MMcf - [(PYPIFF + FD)/214] (or
                                  less if it desires) of Net "B" Contract
                                  Production.  Should CIG fail to take the
                                  volume resulting from the formula 8500 MMcf -
                                  (PYPIFF + FD) of Net "B" Contract Production
                                  during the Summer Months of any calendar
                                  year, CIG shall be entitled to take, on a
                                  daily basis, the volume resulting from the
                                  formula 35 MMcf - [(PYPIFF + FD)/214] (or
                                  less if it desires) of such Production
                                  beginning November 1 until CIG has taken the
                                  volume resulting from the formula 8500 MMcf -
                                  (PYPIFF + FD) during the April through
                                  November period of such calendar year.  By
                                  the 15th day of the month of October, CIG
                                  shall nominate, in writing, such additional
                                  volumes of Net "B" Contract Production which
                                  CIG intends to take in the month of November.

                                  (ii)     CIG shall also be entitled to take,
                                  on a daily basis, all Plant Inlet Field Fuel
                                  used that day.

                                  (iii)     MESA shall be entitled to take, on
                                  the same day, all volumes of Net "B" Contract
                                  Production not taken by CIG on that day.  If
                                  MESA does not take, on the same day, all the
                                  volumes of Net "B" Contract Production which
                                  are in excess of such volumes taken by CIG,
                                  then CIG shall be entitled to take, on that
                                  day, the remaining volumes of Net "B"
                                  Contract Production not taken by MESA.

                          (b)     During the Winter Months:

                                  (i)      Except as provided in Section
                                  3.1.(b)(2)(a)(i) above and subsection b(iii)
                                  below, CIG shall not be entitled to take any
                                  volumes of Net "B" Contract Production.

                                  (ii)     CIG shall be entitled to take, on a
                                  daily basis, all Plant Inlet Field Fuel used
                                  that day.  Subject to the provisions of the
                                  Gas Processing Agreement, MESA shall tender
                                  on a daily basis, to CIG at the tailgate of
                                  the Fain Plant into CIG's pipeline, a volume
                                  of residue gas (in MMBtus) associated with
                                  the Plant Inlet Field Fuel used that day.





                                      -3-
<PAGE>   4
                                  (iii)    MESA shall be entitled to take, on a
                                  daily basis, all volumes of Net "B" Contract
                                  Production.  If MESA does not take, on any
                                  day(s), all the volumes of Net "B" Contract
                                  Production, then CIG shall be entitled to
                                  take, on the same day, the remaining volumes
                                  of Net "B" Contract Production not taken by
                                  MESA.

                          (c)     The volume of Plant Inlet Field Fuel used on
                                  any day shall be deemed the first volumes
                                  taken by CIG on that day.

                          (d)     CIG shall be entitled to take a maximum
                                  volume of Plant Inlet Field Fuel and Net "B"
                                  Contract Production pursuant to subsections
                                  (b)(2)(a)(i), (b)(2)(a)(ii) and (b)(2)(b)(ii)
                                  above equal to 8.5 Bcf per calendar year as
                                  adjusted by the Fuel Difference.

                          (e)     (i)  During each day of the Winter Months of
                                  December through March, at CIG's option, MESA
                                  shall tender to CIG at the tailgate of the
                                  Fain Plant into CIG's pipeline, a volume of
                                  residue gas [in MMBtus] ("Exchange Volumes")
                                  associated with the Exchange Percentage of
                                  Net "B" Contract Production for that day
                                  (less any Net "B" Contract Production taken
                                  by CIG pursuant to Section 3.1.(b)(2)(b)(iii)
                                  above).  Such Exchange Volumes shall be
                                  determined based upon the actual Fain Plant
                                  shrinkage rates.  This option may be
                                  exercised by CIG upon sixty (60) days written
                                  notice prior to each December 1 of such
                                  Winter Months during which it requests
                                  Exchange Volumes.

                                  (ii)     During each day of the Summer Months
                                  immediately following the Winter Months in
                                  which CIG has taken Exchange Volumes, CIG
                                  shall tender to MESA (or for MESA's account)
                                  into Panhandle Eastern Pipe Line at the
                                  CIG-Panhandle Lakin interchange located in
                                  Kearney County, Kansas, or at any other
                                  redelivery point(s) mutually agreed to
                                  (including the Fain Plant tailgate) a volume
                                  of residue gas (in MMBtu's) equal to the
                                  Exchange Volumes.  A redelivery point(s),
                                  other than the Lakin interchange, shall be
                                  mutually agreed to in writing by the Parties
                                  by no later than each December 1 of the
                                  Winter Months immediately preceding the
                                  Summer Months during which the redelivery
                                  will occur.  Such Exchange Volumes shall be
                                  redelivered to MESA on consecutive days
                                  beginning June 1 of such Summer Months over
                                  the same amount of time as the Exchange
                                  Volumes were received by CIG over the Winter
                                  Months at a pro rata volumetric rate or at
                                  any other rate mutually agreed to by the
                                  Parties.





                                      -4-
<PAGE>   5
                                  (iii)    The delivery by MESA to CIG of the
                                  Exchange Volumes shall be at no cost to CIG,
                                  and the redelivery of the equivalent volumes
                                  by CIG to MESA shall be at no cost to MESA
                                  and shall not constitute (1) a basis for cash
                                  balancing under the provisions of Section
                                  6.3, or (2) the taking by CIG of Net "B"
                                  Contract Production for purposes of this
                                  Agreement, or (3) constitute a sale(s) or
                                  exchange(s) for tax purposes under the
                                  Internal Revenue Code of 1986 and the
                                  regulations thereunder.  Instead, such
                                  delivery(ies) and redelivery(ies) will be
                                  deemed for all purposes to be merely an
                                  exchange of gas.

                 3.1.b.(3)        For the calendar year 2000, and subject to
                                  the provisions of Section 3.4 below:

                          (a)     From January 1 through June 30, CIG shall be
                                  entitled to take, on a daily basis, all Plant
                                  Inlet Field Fuel used that day.

                          (b)     During the Summer Months and subject to
                                  3.1.(b)(3)(f) below:

                                  (i)      From April 1 through June 30, CIG
                                  shall be entitled to take, on a daily basis,
                                  the volume resulting from the formula 40 MMcf
                                  - [(PYPIFF + FD)/214] (or less if it desires)
                                  of Net "B" Contract Production.

                                  (ii)     From July 1 through October 31,
                                  subject to Section 3.1.c, CIG shall be
                                  entitled to take, on a daily basis, the
                                  volume resulting from the formula 35 MMcf -
                                  [(PYPIFF + FD)/214] (or less if it desires)
                                  of Net "B" Contract Production.  The formula
                                  in this subsection shall be adjusted as
                                  necessary to reflect the outcome of the Field
                                  Fuel issue set forth in Article IV of this
                                  Agreement.

                                  (iii)    MESA shall be entitled to take, on
                                  the same day, all volumes of Net "B" Contract
                                  Production not taken by CIG on that day.  If
                                  MESA does not take, on the same day, all the
                                  volumes of Net "B" Contract Production which
                                  are in excess of such volumes taken by CIG,
                                  then CIG shall be entitled to take, on that
                                  day, the remaining volumes of Net "B"
                                  Contract Production not taken by MESA.

                          (c)     During the Winter Months:

                                  (i)      Except as provided in subsection
                                  (c)(ii) below, CIG shall not be entitled to
                                  take any volumes of Net "B" Contract
                                  Production.





                                      -5-
<PAGE>   6
                                  (ii)     MESA shall be entitled to take, on a
                                  daily basis, all volumes of Net "B" Contract
                                  Production.  If MESA does not take, on any
                                  day, all the volumes of Net "B" Contract
                                  Production, then CIG shall be entitled to
                                  take, on the same day, the remaining volumes
                                  of Net "B" Contract Production not taken by
                                  MESA.

                          (d)     From July 1 through December 31:

                                  (i)      MESA shall also be entitled to take
                                  Plant Inlet Field Fuel, on a daily basis, as
                                  and to the extent determined pursuant to the
                                  provisions of Article IV of this Agreement.

                                  (ii)     CIG shall also be entitled to take
                                  Plant Inlet Field Fuel, on a daily basis, as
                                  and to the extent determined pursuant to the
                                  provisions of Article IV of this Agreement.
                                  Subject to the provisions of the Gas
                                  Processing Agreement, MESA shall tender to
                                  CIG each day at the tailgate of the Fain
                                  Plant into CIG's pipeline, a volume of
                                  residue gas (in MMBtus) associated with such
                                  Plant Inlet Field Fuel for that day.

                          (e)     The volume of Plant Inlet Field Fuel used on
                                  any day shall be deemed the first volumes
                                  taken by CIG on that day.

                          (f)     Subject to Section 3.1.c., CIG shall be
                                  entitled to take a maximum volume of Plant
                                  Inlet Field Fuel and Net "B" Contract
                                  Production pursuant to subsections (b)(3)(a),
                                  (b)(3)(b)(i), (b)(3)(b)(ii) and (b)(3)(d)(ii)
                                  above equal to 7.56 Bcf for the calendar year
                                  as adjusted by the Fuel Difference.

                    3.1.b.(4)     Beginning January 1, 2001, and subject to the
                                  provisions of Sections 3.1.c. and 3.4 below:

                          (a)     During the Summer Months of each calendar
                                  year and subject to Section 3.1.(b)(4)(f) 
                                  below:

                                  (i)      CIG shall be entitled to take, on a
                                  daily basis, the volume resulting from the
                                  formula 35 MMcf - [(PYPIFF + FD)/214] (or
                                  less if it desires) of Net "B" Contract
                                  Production.  The formula in this subsection
                                  shall be adjusted as necessary to reflect the
                                  outcome of the Field Fuel issue set forth in
                                  Article IV of this Agreement.

                                  (ii)     MESA shall be entitled to take, on
                                  the same day, all volumes of Net "B" Contract
                                  Production not taken by CIG on that day.  If
                                  MESA does not take, on the same day, all the
                                  volumes of





                                      -6-
<PAGE>   7
                                  Net "B" Contract Production, which are in
                                  excess of such volumes taken by CIG, then CIG
                                  shall be entitled to take, on that day, the
                                  remaining volumes of Net "B" Contract
                                  Production not taken by MESA.

                          (b)     During the Winter Months:

                                  (i)      Except as provided in subsection
                                  (b)(ii) below, CIG shall not be entitled to
                                  take any volumes of Net "B" Contract
                                  Production.

                                  (ii)     MESA shall be entitled to take, on a
                                  daily basis, all volumes of Net "B" Contract
                                  Production.  If MESA does not take, on any
                                  day, all the volumes of Net "B" Contract
                                  Production, then CIG shall be entitled to
                                  take, on the same day, the remaining volumes
                                  of Net "B" Contract Production not taken by
                                  MESA.

                          (c)     MESA shall be entitled to take Plant Inlet
                                  Field Fuel, on a daily basis, as and to the
                                  extent determined pursuant to the provisions
                                  of Article IV of this Agreement.

                          (d)     CIG shall be entitled to take Plant Inlet
                                  Field Fuel, on a daily basis, as and to the
                                  extent determined pursuant to the provisions
                                  of Article IV of this Agreement.  Subject to
                                  the provisions of the Gas Processing
                                  Agreement, MESA shall tender to CIG each day
                                  at the tailgate of the Fain Plant into CIG's
                                  pipeline, such Plant Inlet Field Fuel for
                                  that day.

                          (e)     The volume of Plant Inlet Field Fuel used on
                                  any day shall be deemed the first volumes
                                  taken by CIG on that day.

                          (f)     Subject to Section 3.1.c., CIG shall be
                                  entitled to take a maximum volume of Plant
                                  Inlet Field Fuel and Net "B" Contract
                                  Production pursuant to subsections
                                  (b)(4)(a)(i) and (b)(4)(d) above equal to 7.0
                                  Bcf during the calendar year as adjusted by
                                  the Fuel Difference.

         3.1.b.(5)        Except as provided in Section 3.1.b.(2)(a)(i) and
                          except with respect to the Fuel Difference
                          adjustments as described above, neither Party shall
                          have any rights to take additional gas volumes in any
                          daily, monthly or yearly period(s) in order to makeup
                          for its failure to take during an applicable prior
                          period any or all of the entitlements to which it has
                          under Section 3.1.b.





                                      -7-
<PAGE>   8
         7.      Section 3.1.c. of the PAA is deleted in its entirety and the
                 following substituted:

                 3.1.c.    Beginning July 1, 2000, MESA shall be entitled to
                 take, on a daily basis, volumes of Net "B" Contract Production
                 which are in excess of the volumes it is entitled to take
                 under Sections 3.1.b(3)(b)(iii) and 3.1.b(4)(a)(ii) above, but
                 only to the extent that the volumes taken by MESA for that
                 day, and any excess volumes taken pursuant to this Section
                 3.1.c. are required by MESA to meet its volumetric obligations
                 under the Amarillo Supply Agreement as such Agreement existed
                 as of January 1, 1991.

         8.      Effective January 1, 1997, Section 3.5.b. of the PAA is
deleted in its entirety and the following substituted therefor:

                 b.       While the ASSA is in effect, MESA's obligation to
                          make certain volumes of gas available to CIG on
                          certain "Peak Days," by reducing the applicable
                          "Maximum Daily Volume(s)" as specified in the ASSA,
                          shall be satisfied, on a Mcf basis, but only with
                          respect to the amount by which MESA is unable to take
                          such "Maximum Daily Volume(s)" on a Peak Day because
                          it is delivering Exchange Volumes to CIG on that day.
                          The amount by which MESA's "Peak Day" obligation will
                          be satisfied shall be determined pursuant to the
                          following formula:

                          (The lesser of A or B) - (C x B) = Amount of
                          Reduction*

                          A =     Applicable "Maximum Daily Volume" set forth
                                  in the ASSA.  
                          B =     Net "B" Contract Production for
                                  the day.  
                          C =     1 - Exchange Percentage.  
                          * =     MESA's "Peak Day" obligation shall not 
                                  increase, and shall not be reduced by more 
                                  than 15 MMcf/d.

         9.      The following is added to the PAA as new subsection (3) to
Section 3.3b.:

                 (3)      Either CIG or MESA may request a redetermination of
                          Net "B" Contract Production from and after January 1,
                          1991, through Depletion by advance notice as provided
                          in Section 1.33 above.  A Party requesting such a
                          redetermination may not request another such
                          redetermination more often than once every three
                          calendar years thereafter until Depletion.

         10.     The following provisions are added to the PAA as new Section
3.6:

                 3.6      CIG shall have the right at any time to install and
                 operate the pipeline and facilities necessary to take delivery
                 and to make deliveries of gas at the Fain Plant tailgate.
                 MESA shall fully cooperate with CIG's efforts to construct and
                 operate such pipeline and facilities.





                                      -8-
<PAGE>   9
         11.     The phrase "Except as provided in Section 6.1.c. below," in
Section 5.2 of the PAA is deleted.

         12.     Section 6.1 of the PAA is deleted in its entirety.

         13.     Subsections 6.3.a(3) and (4) of the PAA are deleted in their
entirety and the following substituted therefor:

                 (3)      If during any month as a result of Governmental
                          Action either Party cannot take any portion of the
                          Net "B" Contract Production which such Party is
                          entitled to take during that month pursuant to
                          Section 3.1.b. above, then, at the limited Party's
                          option, there shall be a cash balancing, but only
                          with respect to the Net "B" Contract Production
                          portion of the amount by which such limited Party's
                          monthly entitlements as described in Section 3.1
                          exceed the maximum Net "B" Contract Production it can
                          take during such month consistent with such
                          Governmental Action, and only to the extent that the
                          non-limited Party actually takes Net "B" Contract
                          Production in excess of such non-limited Party's
                          monthly Net "B" Contract Production entitlements as
                          described in Section 3.1, excluding those Net "B"
                          Contract Production volumes on any day and/or month
                          during which such non-limited Party could have taken
                          only because the other Party was not taking all of
                          its Net "B" Contract Production entitlement on that
                          same day.  Such cash balancing shall be made within
                          45 days after the end of the month with respect to
                          which such cash balancing is required.

                 (4)      In the event that CIG is prevented by the provisions
                          of Section 3.1.c. above from taking, during any
                          month, any Net "B" Contract Production which CIG is
                          entitled to take during that month pursuant to
                          Section 3.1.b. above, then, at CIG's option, within
                          45 days after the end of that month there shall be a
                          cash balancing, but only with respect to the Net "B"
                          Contract Production portion of the gas volumes that
                          CIG was thus prevented from taking.

         14.     Any and all direct and indirect references to the City of
Amarillo and/or its environs in the State of Texas which have in the past
serve(d) or act(ed), or which have in the past or may in the future be(en)
construe(d) as a limitation(s) and/or restriction(s) upon CIG's obligations to
deliver to MESA, and/or MESA's rights to take the natural gas committed under
the "B" Contract are hereby deleted in their entirety from the "B" Contract,
the PAA and any amendments thereto.  MESA may take, use, process and/or sell
the natural gas committed under the "B" Contract, and/or any of the
hydrocarbons and non-hydrocarbons contained therein anywhere, whether inside or
outside the City of Amarillo and/or its environs, inside and/or outside the
State of Texas.  The Parties agree to make any modifications and amendments to
any other agreement(s) between them necessary to fully implement the intent of
the Parties set forth





                                      -9-
<PAGE>   10
in this paragraph 14 of this Amendment.

         15.     The Parties shall, contemporaneously with the execution of
this Amendment, execute the Gas Processing Agreement.  The Parties agree that
execution of the Gas Processing Agreement is consistent with and satisfies the
provisions of Article XI of the PAA.

         16.     The respective rights and obligations of MESA and CIG with
respect to Field Fuel as described in Article IV of the PAA shall be determined
as if this Amendment never existed.  That is, this Amendment shall not be
admissible or taken into account in any manner whatsoever in determining such
rights and obligations.  Nothing in this Amendment shall be construed as giving
CIG or MESA any additional right, title or interest in or any Field Fuel.

         17.     The prior written consent of MAPCO and Energas Company, a
division of Atmos Energy Corporation ("Energas"), to the terms and conditions
of this Amendment are expressly made conditions precedent to all rights and
obligations of the Parties hereunder; provided, however, that CIG and MESA may
by joint written agreement waive the requirement of the consent of either MAPCO
or Energas.

         18.     This Amendment amends the "B" Contract and the PAA.  However,
the rights and obligations of the Parties under the "B" Contract and the PAA
are amended only to the extent expressly provided for in this Amendment and,
except as respectively amended herein, the provisions of the "B" Contract and
the PAA shall continue in full force and effect.

         19.     All the terms and conditions of this Amendment were prepared
jointly by the Parties hereto and not by any Party to the exclusion of the
other.

         20.     THIS AMENDMENT AND THE LEGAL RELATIONS BETWEEN THE PARTIES
WITH RESPECT TO SUCH AMENDMENT SHALL BE GOVERNED, CONSTRUED AND ENFORCED IN
ACCORDANCE WITH THE LAWS OF THE STATE OF TEXAS WITHOUT REGARD TO RULES
CONCERNING CONFLICTS OF LAWS.

         21.     The terms, covenants and conditions of this Amendment shall
constitute covenants running with the land and shall survive the execution of
this Amendment and shall be binding upon and shall inure to the benefit of the
Parties hereto and their respective successors and assigns.  The Parties hereto
agree to give notice of the existence of this Amendment to any successors and
assigns in interest and make any transfer of any interest in the "B" Contract
acreage or production therefrom subject to the terms of this Amendment.

         22.     The Parties expressly agree that the "B" Contract and the PAA,
and as respectively amended herein, were not and are not intended to benefit
any third party(ies) and shall not do so.  The "B" Contract, the PAA and this
Amendment shall not, at any time, give rise to any claim, demand or cause of
action, whether known or unknown, or contingent or absolute at this time or any
other time, by any such third party(ies) claiming third party beneficiary
rights.





                                      -10-
<PAGE>   11
         23.     This Amendment shall not construed as modifying, in any way,
the terms and conditions of: (a) the Leases, and any amendments thereto,
covering natural gas production from the "B" Contract Wells; (b) that certain
Royalty Agreement dated October 1, 1988, between CIG, MESA and Mary Kritser
Miller et al.; (c) that certain Compromise and Settlement Agreement dated
December 31, 1981, entered into between Francis Diane Neal, et al., as
plaintiffs, and CIG, et al., as Defendants, and Amarillo Oil Company as a Third
Party Defendant in Civil Action No. CA-2-75-68, in the United States District
Court for the Northern District of Texas, Amarillo Division; and (d) that
certain Compromise and Settlement Agreement dated December 31, 1981, between
Mercantile National Bank at Dallas, Trustee, et al., as Plaintiffs, CIG, et
al., as Defendants, and Amarillo Oil Company as a Third Party Defendant.

         24.     This Amendment and the Gas Processing Agreement contains the
entire agreement between the Parties covering the specific matters set forth
herein.  There are no oral promises, inducements or understandings between the
Parties relating to this Amendment.  This Amendment cannot be modified without
the express written authorization of both Parties hereto.

         25.     Exhibit "A" attached to the PAA is hereby amended as follows:

                 a.       The examples set forth in:

                          III.A.
                          III.B. and
                          III.C.

                          are deleted in their entirety;

                 b.       Effective January 1, 1997, the examples set forth in
                          II.E. are deleted in their entirety.

                 c.       The examples set forth in III.G. is deleted in its
                          entirety and replaced with the example for Section
                          6.3.(a)(3) shown on Exhibit "1" to this Amendment.

                 d.       The example set forth in III.H. is deleted in its
                          entirety and replaced with the example for Section
                          6.3.(a)(4) and 6.3.(b) shown on Exhibit "1" to this
                          Amendment.

                 e.       The other examples set forth on Exhibit "1" to this
                          Amendment are hereby added to Exhibit "A" to the PAA.





                                      -11-
<PAGE>   12
         IN WITNESS WHEREOF, the Parties have executed this Agreement effective
as of the date and year first above written.


ATTEST:                                 COLORADO INTERSTATE GAS COMPANY



__________________________________      By:____________________________________
Name:                                       Jon R. Whitney
Title:                                      President and Chief Executive 
                                            Officer




ATTEST:                                 MESA OPERATING LIMITED PARTNERSHIP

                                        By: Pickens Operating Co.,
                                            General Partner



__________________________________      By:___________________________________
Name:                                       Paul W. Cain
Title:                                      President and Chief Operating 
                                            Officer





                                      -12-
<PAGE>   13
STATE OF _________________        )
                                  )
COUNTY OF ________________        )

         BEFORE ME, the undersigned, a Notary Public in and for said County and
State, on this day personally appeared _________________ known to me to be the
person and officer whose name is subscribed to the foregoing instrument and
acknowledged to me that the same was the act of the said
_____________________________ a _____________________ and that he executed the
same as the act of such _____________________ for the purposes and
consideration therein expressed, and in the capacity therein expressed, and in
the capacity therein stated.

         GIVEN UNDER MY HAND AND SEAL OF OFFICE, this the _____ day of ________
__, 199__.


                                        ________________________________________
                                        Notary Public in and for _______________

My Commission Expires:

______________________


STATE OF _________________        )
                                  )
COUNTY OF ________________        )

         BEFORE ME, the undersigned, a Notary Public in and for said County and
State on this day personally appeared ________________________, known to me to
be the person and attorney-in-fact whose name is subscribed to the foregoing
instrument and acknowledged to me that the same was the act of the said MESA
OPERATING LIMITED PARTNERSHIP, a partnership, and that he executed the same as
the act of such partnership for the purposes and consideration therein
expressed, and in the capacity therein stated.

         GIVEN UNDER MY HAND AND SEAL OF OFFICE, this the _____ day of ________
__, 199__.


                                        ________________________________________
                                        Notary Public in and for _______________

My Commission Expires:

______________________





                                      -13-
<PAGE>   14
                                  EXHIBIT "1"

                        TO THE AMENDMENT TO "B" CONTRACT
                      AND PRODUCTION ALLOCATION AGREEMENT

                             DATED JANUARY 1, 1993


Article I

A.       Section 1.39

Assuming the following as of April 1 1998:

         PYPIFF = 3300 MMcf
         1996 Plant Inlet Field Fuel = 3400 MMcf

Then:

The Fuel Difference (FD) for the computation of CIG's 1998 Net "B" Contract
Production Volume is (3300 MMcf - 3400 MMcf) = -100 MMcf.


Section 3.1.b.(2)(a)(i)

Assuming the following as of January 1, 1997:

         PYPIFF = 3000 MMcf
         1995 Plant Inlet Field Fuel = 3100 MMcf

Then:

The Fuel Difference is by definition 0 for the calculation of CIG's 1997 Net
"B" Contract Production entitlement.  Therefore, for the Summer Months of 1997
CIG shall be entitled to take on a daily basis (40  MMcf - (3000  MMcf + 0
MMcf)/ 214) = 26 MMcf/d of Net "B" Contract Production plus Plant Inlet Field
Fuel.  Should CIG fail to take (8500 MMcf - (3000 MMcf + 0 MMcf)) = 5500 MMcf
of Net "B" Contract Production during the Summer Months, CIG shall be entitled
to take (35 MMcf - ((3000 MMcf + 0 MMcf)/214)) = 21 MMcf/d of such production
beginning November 1 until CIG has taken 5500 MMcf of Net "B" Contract
Production during the April through November period of such calendar year.





                                      -1-
<PAGE>   15
Assuming the following as of January 1, 1998:

         PYPIFF = 4000 MMcf
         1996 Plant Inlet Field Fuel = 3000 MMcf

Then:

For 1998 the Fuel Difference is (4000 MMcf - 3000 MMcf) = 1000 MMcf.
Therefore, CIG's 1998 entitlement to Net "B" Contract Production would be (8500
MMcf - (4000 MMcf + 1000 MMcf)) = 3500 MMcf.  CIG's daily entitlement during
the Summer Months of 1998 would be (40 MMcf -[(4000 MMcf + 1000 MMcf) / 214)] =
17 MMcf/d of Net "B" Contract Production plus Plant Inlet Field Fuel.

Assuming the following as of January 1, 1998:

         PYPIFF = 2500 MMcf
         1996 Plant Inlet Field Fuel = 3000 MMcf

Then:

For 1998 the Fuel Difference is (2500 MMcf - 3000 MMcf) = -500 MMcf.
Therefore, CIG's 1998 entitlement to Net "B" Contract Production would become
(8500 MMcf - (2500 MMcf + -500 MMcf)) = 6500 MMcf.  CIG's daily entitlement
during the Summer Months of 1998 would be (40 MMcf - ((2500 MMcf + -500 MMcf)/
214)) = 31 MMcf/d of Net "B" Contract Production plus Plant Inlet Field Fuel.


Section 3.1.b.(2)(a)(iii)

Assuming the following as of July 1, 1998:

         Net "B" Contract Production = 100 MMcf/d
         Plant Inlet Field Fuel = 10 MMcf/d
         CIG's daily entitlement to Net "B" Contract Production from the prior
         example = 31 MMcf/d

Then:

MESA's entitlement to Net "B" Contract Production is (100 MMcf/d - 31 MMcf/d) =
69 MMcf/d.  If CIG takes 35 MMcf/d (10 MMcf Plant Inlet Field Fuel + 25 MMcf
Net "B" Contract Production) MESA shall be allowed to take the 6 MMcf/d ((31
MMcf/d + 10 MMcf/d) - 35 MMcf/d) that CIG did not take, increasing MESA's daily
entitlement to (69 MMcf/d + 6 MMcf/d) 75 MMcf/d.  Conversely, if MESA takes
only 60 MMcf/d CIG shall be entitled to take (31 MMcf/d + 10 MMcf/d + (69
MMcf/d - 60 MMcf/d)) = 50 MMcf/d.





                                      -2-
<PAGE>   16
Section 3.1.b.(2)(d)

Assuming the following as of January 1, 1998

         PYPIFF = 4,000 MMcf
         1996 Plant Inlet Field Fuel = 3,000 MMcf

Then:

For 1998 the Fuel Difference is (4,000 MMcf - 3,000 MMcf) = 1,000 MMcf.
Therefore, CIG's maximum entitlement of Plant Inlet Field Fuel and Net "B"
Contract Production would be 8,500 MMcf - 1,000 MMcf = 7,500 MMcf.


Section 3.1.b.(2)(e)(i)

Assuming the following as of December 1, 1998:

         CIG is the overproduced party by 20 Tbtu
         Net "B" Contract Production = 110 MMcf/d
         Plant Inlet Field Fuel = 10 MMcf/d
         Fain Plant outlet volume is 115 MMcf/d
         Net Non "B" Contract Production = 4 MMcf/d
         Average Fain Plant inlet Btu/cu.ft. = 1200
         Average Fain Plant outlet Btu/cu.ft. = 950
         CIG elected to take its exchange percentage on September 20, 1998
         during the Winter Months

Then:

Fain plant shrinkage is (115 MMcf/d x 950 Btu/cu.ft.) / ((110 MMcf/d + 10
MMcf/d + 4 MMcf/d) x 1200 Btu/cu.ft.)) = 73.4% on a Btu basis.  CIG is entitled
to an exchange volume of (((.1725 x 110 MMcf/d x 1200 Btu/cu.ft.) x .734) / 950
Btu/cu.ft.) = 18 MMcf/d at the outlet of the Fain plant.


Section 3.1.b.(2)(e)(ii)

Assuming the following as of April 1, 1999:

         CIG took an exchange volume of 2200 MMcf during the Winter Months from
         December 1, 1998 through March 31, 1999 Average Fain Plant outlet
         Btu/cu.ft. = 950





                                      -3-
<PAGE>   17
Then:

CIG shall redeliver to MESA (2200 MMcf x 950 Btu/cu.ft.) = 2090 BBtu on a pro
rata basis beginning June 1, 1999.


Section 3.1.b.(3)(b)(i)

Assuming the following as of April 1, 2000:

         PYPIFF = 2000 MMcf
         1998 Plant Inlet Field Fuel = 1900 MMcf

Then:

CIG's daily entitlement to Net "B" Contract Production for the period from
April 1, 2000 to June 30, 2000 is (40 MMcf/d - ((2000 MMcf + 100 MMcf)/ 214)) =
30 MMcf/d.


Section 3.1.b.(3)(b)(ii)

Assuming the following as of July 1, 2000

         PYPIFF = 3000 MMcf
         1998 Plant Inlet Field Fuel = 3300 MMcf

Then:

CIG's daily entitlement to Net "B" Contract Production for the period from July
1, 2000 through October 31, 2000 is (35 MMcf/d - ((3000 MMcf - 300 MMcf)/214))
= 22 MMcf/d.  This calculation is subject to adjustment depending upon the
outcome of the Field Fuel issue set forth in Article IV of the PAA.


Section 3.1.b.(3)(b)(iii)

Assuming the following as of July 1, 2000:

         CIG's Net "B" Contract Production entitlement = 20 MMcf/d
         Net "B" Contract Production = 90 MMcf/d
         CIG takes 15 MMcf/d of Net "B" Contract Production





                                      -4-
<PAGE>   18
Then:

MESA shall be entitled to take (90 MMcf/d - 15 MMcf/d) = 75 MMcf/d.


Section 3.1.b.(3)(f)

Assuming the following as of January 1, 2000

         PYPIFF = 4,000 MMcf
         1998 Plant Inlet Field Fuel = 3,000 MMcf
         MESA is not taking Gas pursuant to Section 3.1.c.

Then:

For 2000, the Fuel Difference is (4,000 MMcf - 3,000 MMcf) = 1,000 MMcf.
Therefore, CIG's maximum entitlement of Plant Inlet Field Fuel and Net "B"
Contract Production for the year 2,000 would be 7,560 MMcf - 1,000 MMcf = 6,560
MMcf.


Section 3.1.b.(4)(a)(i)

Assuming the following as of April 1, 2001:

         PYPIFF = 2200 MMcf
         1999 Plant Inlet Field Fuel = 2000 MMcf

Then:

During the Summer months CIG shall be entitled, on a daily basis, to take (35
MMcf/d - ((2200 MMcf + 200 MMcf)/214)) = 24 MMcf/d of Net "B" Contract
Production.  This calculation is subject to adjustment depending upon the
outcome of the Field Fuel issue set forth in Article IV of the PAA.


Section 3.5.b

Assuming the following for Calendar Year 1997:

         A = 120 MMcf/d
         B = 110 MMcf/d
         C = .8275





                                      -5-
<PAGE>   19
Then:

         110 MMcf/d - (.8275 x 110 MMcf/d) = 19.0 MMcf/d

Therefore:

Since 19 MMcf/d is greater than 15 MMcf/d, MESA has no obligation to make
available Volumes.

Assuming the following for Calendar Year 1997:

         A = 120 MMcf/d
         B = 140 MMcf/d
         C = .8275

Then:

         120 MMcf/d - (.8275 x 140 MMcf/d) = 4.0 MMcf/d

Therefore:

MESA's obligation to make available "Peak Day" Volumes is reduced to 11 MMcf/d
(15 MMcf/d - 4 MMcf/d).

Assuming the following for Calendar Year 1997:

         A = 120 MMcf/d
         B = 150 MMcf/d
         C = .8275

Then:

         120 MMcf/d - (.8275 x 150 MMcf/d) = -4.0 MMcf/d

Therefore:

MESA must make available full "Peak Day" Volumes of 15 MMcf/d.





                                      -6-
<PAGE>   20
Section 3.1.b.(4)(f)

Assuming the following as of January 1, 2001

         PYPIFF = 4,000 MMcf
         1999 Plant Inlet Field Fuel = 3,000 MMcf

Then:

For 2001, the Fuel Difference is (4,000 MMcf - 3,000 MMcf) = 1,000 MMcf.
Therefore, CIG's maximum entitlement of Plant Inlet Field Fuel and Net "B"
Contract Production for the year 2001 would be 7,000 MMcf - 1,000 MMcf = 6,000
MMcf.


Section 6.3.a.(3)

Assuming the following for June 1997:

         MESA is prevented by Governmental Actions from taking its Net "B" 
         Contract Production entitlement of 2.2 TBtu.
         CIG's Net "B" Contract Production entitlement = 1.0 TBtu.
         CIG takes of Net "B" Contract Production = 1.8 TBtu.

Then:

MESA shall be entitled to cash balance on (1.8 TBtu - 1.0 TBtu) = .8 TBtu for
June 1997.


Section 6.3.a.(4)

Assuming the following as of July 1, 2000

         CIG has invoked cash balancing.
         CIG's cumulative Net "B" Contract Production = 120 TBtu
         MESA's cumulative Net "B" Contract Production = 350 TBtu
         The Net "B" Contract Production for July 2001 = 3 TBtu
         During July 2001, MESA takes 2.8 TBtu (pursuant to Section 3.1.c.), 
         and CIG takes .2 TBtu.
         CIG is entitled to take 35 MMcf/d - (PYPIFF + FD/214).
         Average Plant Inlet Btu/cu ft. = 1,200
         PYPIFF = 3,000 MMcf
         1998 Plant Inlet Field Fuel = 2,500 MMcf





                                      -7-
<PAGE>   21
Then:

CIG's daily entitlement = 35 MMcf - [(3,000 + 500)/214] = 18.6 MMcf.  CIG's
monthly entitlement = 576.6 MMcf = .7 TBtu.

MESA shall cash balance with CIG on .7 TBtu - .2 TBtu = .5 TBtu.





                                      -8-

<PAGE>   1
                                                                   EXHIBIT 10.25

                     AGREEMENT OF COMPROMISE AND SETTLEMENT


         This AGREEMENT OF COMPROMISE AND SETTLEMENT dated January 11, 1994
(this "Settlement Agreement") is entered into by and among Unocal Corporation,
a Delaware corporation ("Unocal"), David Colan, a Unocal stockholder ("Colan"),
MESA Inc., a Texas corporation ("Mesa"), the other Mesa Entities listed on
Exhibit 1 hereto and the WB Entities listed on Exhibit 2 hereto.

                                    RECITALS

         A.      On or about June 3, 1986, Colan filed suit (the "Action") in
the United States District Court for the Central District of California (the
"Court") on behalf of Unocal against certain of the Mesa and WB Entities (the
"Defendants").  The Action is styled and numbered Colan et al. v. Mesa
Petroleum Co. et al., Case No. 86-3564-JGD (Tx).

         B.      On or about August 24, 1989, Unocal, which originally had been
named as a nominal defendant in the Action, was realigned as a plaintiff.
Colan and Unocal are collectively referred to herein as the "Plaintiffs".

         C.      In the Action, Plaintiffs have alleged, inter alia, that
Unocal is entitled to recover pursuant to Section 16(b) of the Securities
Exchange Act of 1934 certain profits allegedly realized by Defendants in
connection with certain transactions in Unocal securities that occurred in
1985.  Defendants have denied that any such profits were realized or are
recoverable by Unocal under Section 16(b).

         D.      Plaintiffs claim that Unocal is entitled to recover from
Defendants approximately $99 million in Section 16(b) profits because
Defendants bought and sold additional Unocal common shares within a six-month
period, thereby realizing short-swing profits, at a time when Defendants
beneficially owned more than 10% of Unocal's common shares.  Plaintiffs claim
that Defendants bought 6.7 million shares of Unocal stock at a price of $48.00
per share (with a 10 cents per share commission) in a series of separate
incremental purchases spanning several days in late March 1985 through
Jefferies & Co., as Defendants' agent.  Plaintiffs claim that of these
purchases, Defendants bought 3.7 million shares of Unocal stock after having
crossed the 10% threshold.  Plaintiffs claim that for the purposes of Section
16(b) Defendants became the beneficial owner of the Unocal shares as they were
purchased by Jefferies.  Plaintiffs further claim that as a result of the May
20, 1985 settlement agreement which allowed Defendants to participate in
Unocal's Exchange Offer, Defendants sold approximately 7.8 million Unocal
shares and realized short-swing profits of approximately $99 million on the
aforesaid 3.7 million shares.

         E.      Defendants contend that they purchased the 6.7 million shares
of Unocal stock on March 27, 1985 at a price of $48.10 per share in a single
block trade from Jefferies & Co., as a principal.  Accordingly, Defendants
contend that none of the shares were subject to Section 16(b), because
Defendants made a single purchase by which they became a more than 10% owner
and that they made no further purchases thereafter.  Defendants further contend
that even if a portion of the 6.7 million shares were subject to Section 16(b)
if sold at a profit within six months, Defendants made no profit.
<PAGE>   2
         F.      Although Plaintiffs have contended in this lawsuit that the
proper valuation of the Unocal shares that Defendants sold into the Unocal
Exchange Offer was about $75.00 per share for purposes of Section 16(b),
Defendants have consistently rejected this analysis, noting that Unocal itself
has stated to the Internal Revenue Service that Unocal paid Defendants only
$31.50 per share and that the remaining consideration paid by Unocal was to
bring about a successful ending of Defendants' takeover threat.  Unocal has
maintained in this litigation that fragmentation is appropriate for tax
purposes but not for Section 16(b) purposes.  Defendants also contend there was
no profit because the sales price per share for purposes of Section 16(b)
should, by virtue of the terms of the Unocal Exchange Offer, be computed on a
"blended value" basis and thus was less than the $48.10 purchase price.
Plaintiffs understand that there is a substantial dispute about the proper
valuation of the stock for Section 16(b) purposes and a significant risk that
the judge or jury might adopt Defendants' position and conclude or find that
there was no Section 16(b) profit.

         G.      The parties' allegations and denials are set forth in more
detail in Plaintiffs' Amended and Supplemental Complaint filed on September 13,
1993 (the "Complaint") and Defendants' answers on file in the Action to which
reference is made for all purposes.

         H.      Prior to the execution of this Settlement Agreement, counsel
for Plaintiffs conducted a thorough examination into the facts, circumstances,
transactions and law relating to and surrounding the allegations set forth in
the Complaint.  This investigation has included the production, review and
analysis of documents from many of the Defendants and third parties, the taking
of depositions, interviews of witnesses, inspection of publicly available
documents, and review of related proceedings.  As a result, inter alia, of the
institution of the Action and the Plaintiffs' prosecution thereof, including
the pretrial proceedings described above, extensive settlement discussions were
ultimately held between the Plaintiffs and the Defendants and their respective
counsel.  These settlement discussions have culminated in the agreements set
forth in this Settlement Agreement.  The Plaintiffs and their respective
counsel have concluded that the settlement of this litigation on the terms set
forth herein is fair, reasonable and adequate and in the best interests of
Unocal and its stockholders.

         I.      Plaintiffs have pursued the Action for more than seven years
and firmly believe in the merits of the Action.  Nevertheless, Plaintiffs have
agreed to settle the Action pursuant to the terms of this Settlement Agreement
after considering: (i) the substantial benefits to Unocal and its stockholders
that will be realized as a result of the settlement; (ii) the risk of
protracted litigation, the outcome of which would be uncertain in light of the
numerous disputed issues of law and fact as to the Action (and, in particular,
the uncertainty regarding the sales price for Section 16(b) purposes of the
stock sold by the Defendants in Unocal's Exchange Offer and whether Unocal
could prove that a profit was realized) and (iii) the conclusion of counsel for
Unocal and counsel for Colan that the settlement is fair, reasonable and
adequate and in the best interests of Unocal and its stockholders.

         J.      Defendants deny any liability with respect to any and all of
the purported facts or claims alleged in the Complaint and other papers filed
in the Action, but consider it desirable that the Action be compromised,
settled and dismissed on the terms set forth in this Settlement Agreement
because such compromise, settlement and dismissal would eliminate the
controversy between the Plaintiffs and the Defendants, would lead to the
avoidance of further expense,





                                      -2-
<PAGE>   3
inconvenience and devotion of employee and executive time and effort to this
Action, and would remove the constraints upon Defendants' business which have
resulted from the pendency of the Action.

         FOR AND IN CONSIDERATION of the mutual covenants contained herein, the
parties, intending to be legally bound hereby, and subject, inter alia, to the
approval of the Court, agree as follows:

                 1.       Payment

                          (a)  The term "Effective Date" means the date on
which payment is made hereunder and shall be the earliest date after the
Judgment Date upon which Mesa can complete the issuance and sale of the Secured
Notes referred to below, but in any event not later than 60 calendar days after
the Judgment Date.  The term "Judgment Date" means the day on which the Court
enters the Judgment, as provided in paragraph 2 below.  The term "Interest
Accrual Date" means the 10th business day after the Judgment Date.  The term
"Secured Notes" means Mesa's 12 3/4% Secured Discount Notes due June 30, 1998.

                          (b)  Subject to and upon the terms and conditions set
forth herein, Defendants will pay to Unocal in cash on the Effective Date the
sum of $47.5 million (the "Settlement Amount"), with $42.75 million of such
amount to be paid by Mesa and $4.75 million by the WB Entities.  If the
Effective Date is later than the Interest Accrual Date, payment of such amount
shall be accompanied by interest thereon at an annual rate of (i) 10% from the
Interest Accrual Date to the 40th calendar day after the Judgment Date and (ii)
12% from such 40th day to the Effective Date.

                          (c)  It is understood that Mesa intends to register
under applicable securities laws and to issue and sell to one or more third
parties its Secured Notes in an aggregate principal amount sufficient to
generate cash proceeds equal to all or substantially all of the amount payable
by Mesa hereunder.  Mesa anticipates that it will be able to effect such a
registration and sale on terms acceptable to it by the date contemplated in the
first sentence of paragraph 1(a), and it will use all reasonable efforts to do
so.  If Mesa is not able to do so by such date, either (i) Unocal may at its
option immediately declare this Settlement Agreement null and void and of no
further force and effect, with the consequences set forth in paragraph 4(d), or
(ii) if Unocal does not do so, the parties shall enter into further
negotiations regarding a mutually agreeable settlement (but if no such mutual
agreement is reached promptly, this Settlement Agreement shall become null and
void and of no further force and effect, with the consequences set forth in
paragraph 4(d)).

                          (d)     All cash payments made hereunder shall be
paid by wire transfer of immediately available funds to an account designated
by Unocal.

                 2.       Approval and Judgment

                          (a)     Plaintiffs and Defendants, through their
respective counsel, shall jointly request that the Court approve this
Settlement Agreement pursuant to applicable law.





                                      -3-
<PAGE>   4
Counsel for the parties shall submit to the Court a proposed Order (in the form
attached hereto as Exhibit 3) providing, among other things, for the following:

                                  (i)      approving the form and content of
         the notice, substantially in the form of Exhibit 4 hereto, to be
         provided by Unocal to its current security holders as of the date of
         preliminary approval and providing for the manner of and time for
         giving such notice (the "Notice"); and

                                  (ii)     scheduling a hearing (the "Hearing")
         to determine the fairness, reasonableness, and adequacy of the
         Settlement provided for in this Settlement Agreement and whether it
         should be approved by the Court.

                          (b)     At the Hearing at which final approval by the
Court of this Settlement Agreement is sought, counsel for the parties shall
jointly submit to the Court a proposed Judgment in substantially the form
annexed hereto as Exhibit 5 that shall constitute, if entered, a final judgment
pursuant to F.R.Civ.P. 54.  Such Judgment shall:

                                  (i)      find that adequate notice has been
         given;

                                  (ii)     approve the settlement provided for
         in this Settlement Agreement and adjudge its terms to be fair,
         reasonable and adequate, directing consummation according to its terms
         and provisions, and retaining jurisdiction over the parties hereto for
         the sole purpose of effectuating this Settlement Agreement;

                                  (iii)    dismiss on the merits and with
         prejudice the Action;

                                  (iv)     bar and permanently enjoin
         Plaintiffs and any and all of Unocal's security holders from
         prosecuting any claims against any of the Mesa Entities or WB Entities
         or against the Mesa Entities' or WB Entities' present or former
         officers, directors, partners, employees, agents, attorneys,
         representatives, advisors, auditors, commercial or investment bankers,
         affiliates and associates, corporate parents or subsidiaries, and each
         of their respective heirs, executors, administrators, successors and
         assigns which arise out of, relate to, or are in any way connected
         with the Settlement Agreement, the Action or any of the matters
         claimed, asserted or alleged or that could have been claimed, asserted
         or alleged in the Action;

                                  (v)      providing that all parties will bear
         their own fees (including attorneys' fees), costs and expenses; and

                                  (vi)     containing such other and further
         provisions consistent with the terms and provisions of this Settlement
         Agreement as the Court may deem appropriate.

                 3.       Mutual Releases.

                          (a)     For and in consideration of the agreements
contained herein, upon the Effective Date, the parties hereto release one
another as follows:





                                      -4-
<PAGE>   5
                                  (i)      Unocal.  Unocal, together with its
         counsel in the Action, on behalf of itself and all of its affiliates,
         successors and assigns ("related parties"), hereby releases, acquits
         and forever discharges each of the Mesa Entities and the WB Entities,
         together with their respective present and former affiliates,
         officers, directors, partners, employees, agents, attorneys,
         successors and assigns, of and from any and all claims, causes of
         action (whether at law or equity), demands, expenses and damages which
         Unocal or its related parties may have had, or may now have, or may
         hereafter have (whether through operation of law, assignment or
         subrogation), from the beginning of time to the Effective Date, known
         or unknown, actual or contingent, relating to or arising out of this
         Settlement Agreement, the Action or any of the matters claimed,
         asserted or alleged, or that could have been claimed, asserted or
         alleged, in the Action.

                                  (ii)     Colan.  Colan, together with his
         counsel in the Action, on behalf of himself and all of his affiliates,
         successors and assigns ("related parties"), hereby releases, acquits
         and forever discharges each of the Mesa Entities and WB Entities,
         together with their respective present and former affiliates,
         officers, directors, partners, employees, agents, attorneys,
         successors and assigns, of and from any and all claims, causes of
         action (whether at law or equity), demands, expenses and damages which
         Colan or his related parties may have had, or may now have, or may
         hereafter have (whether through operation of law, assignment or
         subrogation), from the beginning of time to the Effective Date, known
         or unknown, actual or contingent, relating to or arising out of this
         Settlement Agreement, the Action or any of the matters claimed,
         asserted or alleged, or that could have been claimed, asserted or
         alleged, in the Action.

                                  (iii)    Mesa Entities.  Each of the Mesa
         Entities, together with their counsel in the Action, on behalf of
         itself and all of its affiliates, successors and assigns ("related
         parties"), hereby releases, acquits and forever discharges Unocal and
         Colan, together with their respective present and former affiliates,
         officers, directors, employees, agents, attorneys, successors and
         assigns, of and from any and all claims, causes of action (whether at
         law or equity), demands, expenses and damages which such Mesa Entity
         or its related parties may have had, or may now have, or may hereafter
         have (whether through operation of law, assignment or subrogation),
         from the beginning of time to the Effective Date, known or unknown,
         actual or contingent, relating to or arising out of this Settlement
         Agreement, the Action or any of the matters claimed, asserted or
         alleged, or that could have been claimed, asserted or alleged, in the
         Action.

                                  (iv)     WB Entities.  Each of the WB
         Entities, together with their counsel in the Action, on behalf of
         itself and of all its affiliates, successors and assigns ("related
         parties"), hereby releases, acquits and forever discharges Unocal and
         Colan, together with their respective present and former affiliates,
         officers, directors, employees, agents, attorneys, successors and
         assigns, of and from any and all claims, causes of action (whether at
         law or equity), demands, expenses and damages which such WB Entity or
         its related parties may have had, or may now have, or may hereafter
         have (whether through operation of law, assignment or subrogation),
         from the beginning of time to the Effective Date, known or unknown,
         actual or contingent, relating to or arising out of this Settlement
         Agreement, the Action or any of the matters claimed, asserted or
         alleged, or that could have been claimed, asserted or alleged, in the
         Action.





                                      -5-
<PAGE>   6
                          (b)     With respect to each of the releases set
forth in subparagraph (a) above and the provisions of paragraph 2(b)(iv) above,
each person or entity granting or receiving such a release (i) agrees that such
releases do not preclude any party hereto from seeking to enforce any
undertaking or promise contained in this Settlement Agreement; (ii) agrees not
to pursue with or before any federal, state or other governmental authority or
court any claim or complaint against any of the persons or parties released in
subparagraph (a) above, relating to this Settlement Agreement (other than the
enforcement of any undertaking or promise contained herein), the Action, or any
of the claims, assertions or allegations made or that could have been made in
the Action; and (iii) expressly waives all rights and benefits each may have
under and by virtue of the terms of Section 1542 of the California Civil Code,
which provides as follows:

                 A general release does not extend to claims which the creditor
                 does not know or suspect to exist in his favor at the time of
                 executing the release, which if known by him must have
                 materially affected his settlement with the debtor.

                 4.       Miscellaneous

                          (a)     This Settlement Agreement and any proceedings
taken hereunder are not and shall not in any way be construed as or deemed to
be evidence of (i) any admission or concession on the part of the Plaintiffs
(or their counsel or any of them) of the merits or lack of merits of this
Action, or (ii) any admission or concession on the part of the Mesa Entities
and WB Entities or any of them (or their counsel or any of them) of any
liability or wrongdoing whatsoever, which liability and wrongdoing are hereby
expressly denied and disclaimed by each of the Defendants and are denied and
disclaimed by the other Mesa Entities and WB Entities.

                          (b)     The parties agree that this Settlement
Agreement is entered into without duress, in good faith, for sufficient
consideration, and is fair, just and reasonable to all parties.

                          (c)     This Settlement Agreement is entered into
with full knowledge of any and all rights which the parties may have by reason
of the pending litigation.  All parties have received or have had made
available to them all financial and other information they or their counsel
considered necessary to an informed judgment concerning the Settlement
Agreement.  Each party has received independent legal advice, has conducted
such investigation as he or his counsel thought appropriate, and has consulted
with such other independent advisors as each of them and their counsel deemed
appropriate, regarding the Settlement and their rights and asserted rights in
connection therewith.  None of the parties is relying upon any representations
or statements made by any other party, or such other party's employees, agents,
representatives or attorneys, regarding this Settlement Agreement or its
preparation except to the extent such representations are expressly
incorporated herein.

                          (d)     In the event that this Settlement Agreement
is not approved by the Court by April 30, 1994, or is modified in any respect
by the Court, or such approval is reversed on appeal, or this Settlement
Agreement is otherwise terminated, this Settlement Agreement shall become null
and void and of no further force and effect, and shall not be used or referred
to for any purpose whatsoever.  In such event, this Settlement Agreement and
all negotiations and





                                      -6-
<PAGE>   7
proceedings relating thereto shall be deemed to be without prejudice as to the
rights of any and all parties hereto, who shall be restored, to the extent
possible, to their respective positions existing immediately prior to the date
of this Settlement Agreement (such restoration to include, without limitation,
the repayment by Unocal to the Defendants of all payments made pursuant to
Section 1 hereof together with interest thereon at an annual rate of 7.5% from
the date Unocal received such payment to the date Unocal repays such amount.)
Further, in such event, the parties shall jointly request the Court to set the
earliest practicable trial date.

                          (e)     The terms and provisions of that Stipulation
and Protective Order dated October 10, 1986 shall continue in full force and
effect and will survive the entry of the Judgment contemplated by this
Settlement Agreement.

                          (f)     All parties hereto agree to exercise all
reasonable efforts and to take all reasonable steps necessary to effectuate the
settlement set forth in this Settlement Agreement.

                          (g)     This Settlement Agreement shall be binding
upon and inure to the benefit of the parties hereto and their respective heirs,
successors and assigns, and upon any corporation or other entity into or with
which any party hereto may merge, combine or consolidate.

                          (h)     This Settlement Agreement shall be governed
by and construed and enforced in accordance with the laws of the State of
Delaware, without reference to the conflict of laws principles thereof.

                          (i)     Exhibits 3, 4 and 5 hereto are in draft form,
and the parties shall promptly agree upon final forms thereof.  This Settlement
Agreement, including the  exhibits, constitutes the entire agreement among the
parties with regard to the subject matter hereof and may not be modified or
amended except in writing signed by Unocal, the Mesa Entities and the WB
Entities.

                          (j)     This Settlement 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.

                          (k)     Each person executing this Settlement
Agreement represents that he or it has read and fully understands this
Settlement Agreement and that he or it has the authority to execute this
Settlement Agreement in the capacity identified below.





                                      -7-
<PAGE>   8
                 IN WITNESS WHEREOF, the parties hereto have caused this
Settlement Agreement to be executed as of the date first above written.

                            
                             

                                       _________________________________
                                       DAVID COLAN
                             
                             
                                       UNOCAL CORPORATION
                             
                             
                             
                                       By ______________________________
                                          
                             
                             
                                       MESA INC.,
                                       MESA PETROLEUM CO.,
                                       MESA LIMITED PARTNERSHIP,
                                       MESA SOUTHERN CO.,
                                       MESA EASTERN CO.,
                                       MESA ASSET CO.,
                                       MESA HOLDING LIMITED PARTNERSHIP,
                                       MESA OPERATING LIMITED PARTNERSHIP,
                                       MESA MIDCONTINENT LIMITED PARTNERSHIP,
                                       MESA HOLDING CO.,
                                       MESA OPERATING CO.,
                                       MESA MIDCONTINENT CO., and
                                       MESA PARTNERS II
                             
                             
                             
                                       By ______________________________
                                         
                             
                             
                             
                                       _________________________________
                                       T. BOONE PICKENS, JR.
                             
                             
                                       PICKENS OPERATING CO.
                             
                             
                             
                                       By ______________________________
                                        
                             
                             
                             
                             
                             
                                      -8-
<PAGE>   9
                                      CY-41, INC.


                                      By______________________________________
                                        


                                      JACK-41, INC.



                                      By______________________________________
                                      
                      

                                      _______________________________________
                                      CYRIL WAGNER, JR.



                                      ________________________________________
                                      JACK E. BROWN


                                      WAGNER & BROWN
                                      WAGNER & BROWN II
                                      BROWN & WAGNER



                                      By______________________________________
                                        
                      

                                      WAGNER & BROWN, LTD.

                                      By: Canyon Energy, Inc., its Managing
                                          General Partner


                                      By______________________________________
                                        
                      




                                      -9-
<PAGE>   10
                                     DARRYL SNIDER
                                     SHEARMAN & STERLING
                                     725 SOUTH FIGUEROA STREET
                                     21ST FLOOR
                                     LOS ANGELES, CALIFORNIA  90017-5421
                            
                                     JASMINA A. THEODORE
                                     UNOCAL CORPORATION
                                     1201 WEST FIFTH STREET
                                     LOS ANGELES, CALIFORNIA  90017
                                     (213) 977-5353
                            
                                     Attorneys for Plaintiff, UNOCAL CORPORATION
                            
                                     By_____________________________________   
                                       
                            
                                     WILLIAM LERACH
                                     PATRICK COUGHLIN
                                     MILBERG WEISS BERSHAD
                                     HYNES & LERACH
                                     600 West Broadway, Suite 1800
                                     San Diego, California  92101
                                     (619) 231-1058
                            
                                     Attorneys for Plaintiff DAVID COLAN
                            

                                     By_____________________________________    
                                       
                            
                            
                            
                            
                            
                                      -10-
<PAGE>   11
                                  MICHAEL H. DIAMOND
                                  DAVID S. SHUKAN
                                  SKADDEN, ARPS, SLATE, MEAGHER & FLOM
                                  300 South Grand Avenue
                                  Suite 3400
                                  Los Angeles, California  90071-3144
                                  (213)  687-5000
                      
                                  JAMES EDWARD MALONEY
                                  JOSEPH A. CIALONE II
                                  DAVID D. STERLING
                                  BAKER & BOTTS, L.L.P.
                                  One Shell Plaza
                                  Houston, Texas  77002-4995
                                  (713)  229-1234
                                  
                                  Attorneys for Defendants
                                  MESA PETROLEUM CO., MESA
                                  SOUTHERN CO., MESA ASSET CO.,
                                  CY-41, INC., JACK-41, INC.
                                  MESA LIMITED PARTNERSHIP,
                                  MESA OPERATING LIMITED PARTNERSHIP,
                                  MESA HOLDING LIMITED PARTNERSHIP,
                                  MESA MIDCONTINENT LIMITED PARTNERSHIP
                                  and MESA INC.
                              
                      
                      
                                  By____________________________________
                                   
                      
                                  SETH M. HUFSTEDLER
                                  DENNIS M. PERLUSS
                                  DAN MARMALEFSKY
                                  HUFSTEDLER, KAUS & ETTINGER
                                  355 So. Grand Avenue
                                  Thirty-Ninth Floor
                                  Los Angeles, California  90071-3101
                                  (213) 617-7070
                              
                                  Attorneys for Defendants
                                  PICKENS OPERATING CO.
                                  and T. BOONE PICKENS, JR.
                              
                      
                                  By____________________________________
                                    
                      
                      
                      
              
                      
                                      -11-

<PAGE>   1
 
                                                                      EXHIBIT 12
 
                                   MESA INC.
 
             COMPUTATION OF THE RATIO OF EARNINGS TO FIXED CHARGES
 
     The following computations of the ratio of earnings to fixed charges for
the years ended December 31, 1988, 1989, 1990, 1991 and 1992 and for the nine
month periods ended September 30, 1992 and 1993 represent the actual results of
Mesa's operations for those periods. The computations of the pro forma ratio of
earnings to fixed charges for the year ended December 31, 1992 and for the nine
month periods ended September 30, 1992 and 1993 assume that $42.8 million
accreted value of additional Secured Notes was issued on January 1 of the
respective periods and assume that the general partner's minority interest in
Mesa's subsidiaries was converted to Common Stock on January 1 of the respective
periods.
  
<TABLE>
<CAPTION>
                                                                     PRO FORMA                                      
                                                        ----------------------------------                          
                                                         NINE MONTHS ENDED                   NINE MONTHS ENDED      
                                                            SEPTEMBER 30       YEAR ENDED       SEPTEMBER 30        
                                                        --------------------  DECEMBER 31,  --------------------    
                                                          1993        1992        1992        1993        1992      
                                                        --------    --------  ------------  --------    --------    
<S>                                                     <C>         <C>       <C>           <C>         <C>         
Pre-tax income (loss) . . . . . . . . . . . . . . . .   $(65,737)   $(78,996)   $(98,711)   $(59,013)   $(71,723)   
Adjustments --                                                          
  Loss on investment accounted for                                                                 
    under the equity method . . . . . . . . . . . . .         --          --          --          --          --    
  Minority interest in income (loss)  . . . . . . . .         --          --          --      (2,549)     (3,098)   
  Interest expense  . . . . . . . . . . . . . . . . .    109,175     112,304     149,017     105,000     108,129    
                                                        --------    --------    --------    --------    --------    
      Total Earnings  . . . . . . . . . . . . . . . .   $ 43,438    $ 33,308    $ 50,306    $ 43,438    $ 33,308    
                                                        --------    --------    --------    --------    --------    
                                                        --------    --------    --------    --------    --------    
Fixed charges:                                                              
  Interest expense  . . . . . . . . . . . . . . . . .   $109,175    $112,304    $149,017    $105,000    $108,129    
                                                        --------    --------    --------    --------    --------    
                                                        --------    --------    --------    --------    --------    
Ratio of earnings to fixed charges  . . . . . . . . .      (a)         (a)        (a)          (a)         (a)       
                                                        --------    --------    --------    --------    --------    
                                                        --------    --------    --------    --------    --------    
Fixed charges in excess of                                                                    
  earnings(a) . . . . . . . . . . . . . . . . . . . .   $ 65,737    $ 78,996    $ 98,711    $ 61,562    $ 74,821    
                                                        --------    --------    --------    --------    --------    
                                                        --------    --------    --------    --------    --------    
</TABLE>                                                                


<TABLE>
<CAPTION>
                                                                        YEAR ENDED DECEMBER 31
                                                        ---------------------------------------------------------
                                                          1992        1991        1990         1989        1988
                                                        --------    --------    ---------    --------    --------
<S>                                                     <C>         <C>         <C>          <C>         <C>
Pre-tax income (loss) . . . . . . . . . . . . . . . .   $(89,232)   $(79,163)   $(200,276)   $(60,414)   $ 44,181
Adjustments --                                                          
  Loss on investment accounted for                                                                 
    under the equity method . . . . . . . . . . . . .         --          --           --      13,268       3,241
  Minority interest in income (loss)  . . . . . . . .     (3,854)     (3,419)      (8,649)     (2,609)      1,908
  Interest expense  . . . . . . . . . . . . . . . . .    143,392     150,770      186,700     183,908     111,058
                                                        --------    --------    ---------    --------    --------    
      Total Earnings  . . . . . . . . . . . . . . . .   $ 50,306    $ 68,188    $ (22,225)   $134,153    $160,388
                                                        --------    --------    ---------    --------    --------    
                                                        --------    --------    ---------    --------    --------    
Fixed charges:                                                              
  Interest expense  . . . . . . . . . . . . . . . . .   $143,392    $150,770    $ 186,700    $183,908    $111,058
                                                        --------    --------    ---------    --------    --------    
                                                        --------    --------    ---------    --------    --------    
Ratio of earnings to fixed charges  . . . . . . . . .     (a)         (a)          (a)         (a)           1.44
                                                        --------    --------    ---------    --------    --------    
                                                        --------    --------    ---------    --------    --------    
Fixed charges in excess of                                                                    
  earnings(a) . . . . . . . . . . . . . . . . . . . .   $ 93,086    $ 82,582    $ 208,925    $ 49,755          --
                                                        --------    --------    ---------    --------    --------    
                                                        --------    --------    ---------    --------    --------    
</TABLE>    
 
- ---------------
 
(a) Earnings were not adequate to cover fixed charges in the indicated periods.

<PAGE>   1
 
                                                                    EXHIBIT 23.1
 
                   CONSENT OF INDEPENDENT PUBLIC ACCOUNTANTS
 
     As independent public accountants, we hereby consent to the use of our
reports and to all references to our Firm included in or made a part of this
Registration Statement.
 
                                            ARTHUR ANDERSEN & CO.
 
Houston, Texas
January 14, 1994

<PAGE>   1
 
                                                                    EXHIBIT 23.2
 
                            DEGOLYER AND MACNAUGHTON
                               ONE ENERGY SQUARE
                              DALLAS, TEXAS 75206
 
                                January 12, 1994
 
MESA Inc.
Mesa Operating Co.
Mesa Capital Corporation
2600 Trammell Crow Center
2001 Ross Avenue
Dallas, Texas 75201
 
Gentlemen:
 
     We hereby consent to the reference to reserves and revenue extracted from
our "Appraisal Report as of December 31, 1992 on Certain Properties owned by
MESA Inc." and reference to our name in the Registration Statement on Form S-1
of MESA Inc., Mesa Operating Co., and Mesa Capital Corporation under the
headings "Business," "Experts," and "MESA Inc. -- Supplemental Financial Data";
provided, however, (i) the report pertains to values for only a selected portion
of the total properties included in the MESA Inc. Form 10-K; consequently, our
estimates have been combined with estimates prepared by MESA Inc.'s engineers
and we are necessarily unable to verify the accuracy of the aggregate reserves,
revenue, and discounted present worth; and (ii) we are in the early stages of
preparing estimates of proved reserves of these selected properties owned by
MESA Inc., as of December 31, 1993, and are not presently aware of any material
changes, other than production, in the estimated quantities of reserves of the
selected properties to be included in our report.
 
                                            Very truly yours,
 
                                            /s/  DeGOLYER and MacNAUGHTON
                                            -----------------------------
                                            DeGOLYER and MacNAUGHTON


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