FRONTIER NATURAL GAS CORP
8-K, 1996-10-11
CRUDE PETROLEUM & NATURAL GAS
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<PAGE>
 
                      SECURITIES AND EXCHANGE COMMISSION
                            WASHINGTON, D.C.  20549



                                   FORM 8-K



                                CURRENT REPORT

                    Pursuant to Section 13 or 15 (d) of the
                        Securities Exchange Act of 1934

     Date of Report (date of earliest event reported):  September 27, 1996

                       FRONTIER NATURAL GAS CORPORATION
            ------------------------------------------------------
            (Exact name of registrant as specified in its charter)



                                   Oklahoma
                 ---------------------------------------------
                (State or other jurisdiction of incorporation)


          0-22782                                          73-1421000
   ------------------------                         -----------------------
   (Commission File Number)                              (IRS Employer
                                                      Identification No.)



      One Allen Center, 500 Dallas Street, Suite 2920, Houston, TX 77002
      ------------------------------------------------------------------
                               (Current Address)

      Registrant's telephone number, including area code: (713) 739-7100
                                                          --------------

            9400 North Broadway, Suite 120, Oklahoma City, OK 73102
            -------------------------------------------------------
                               (Former Address)
<PAGE>
 
ITEM 2.   Acquisition or Disposition of Assets.

     On September 27, 1996, Frontier Inc. and Frontier Acquisition Corporation,
wholly owned subsidiaries of Frontier Natural Gas Corporation (the
"Registrant"), sold their interest in nineteen producing oil and gas properties
in Major County, Oklahoma to OXY USA Inc.("OXY") effective September 1, 1996.
The total purchase price was valued at $3,550,000.00.  The Registrant received
$2,840,000.00 in cash and certain properties from OXY in exchange for the
nineteen producing oil and gas properties.  In a separate simultaneous
transaction, properties received from OXY were sold to Special Energy
Corporation for $710,000.00 in cash.  As a result of the two transactions the
total proceeds from the property sale totaled $3,550,000.  The proceeds were
used to reduce debt and to unwind a portion of a swap agreement for Mid-
Continent Natural Gas.  The Registrant will recognize a loss of $212,000.00 as a
result of the swap agreement transaction in the third quarter of 1996.

     The book value of the properties on the effective date is approximately
$3,540,000.00.  The properties sold were estimated to contain 5,250 MMCFE of
natural gas as of December 31, 1995 based on the Registrant's December 31, 1995
reserve report.

ITEM 7.   Financial Statements and Exhibits
 
(b)  Pro Forma Financial Information

     As of the filing date of this Current Report on Form 8-K, it is
impracticable for the Registrant to provide the pro forma financial information
required by this Item 7(b). In accordance with Item 7(b) of Form 8-K, such pro
forma financial information shall be filed by amendment to this Form 8-K no
later than 60 days after October 11, 1996.

(c)  Exhibits

     Exhibit 10.1 Exchange Agreement between OXY USA INC. and Frontier, Inc. and
Frontier Acquisition Corporation entered into as of September 1, 1996.

     Exhibit 10.2 Sale Agreement between Frontier Acquisition Corporation and
Special Energy Corporation entered into as of September 27, 1996.

     Exhibit 99.1 Press Release dated October 7, 1996.
<PAGE>
 
                                  SIGNATURES

Pursuant to the requirements of the Securities and Exchange Act of 1934, the
registrant has duly caused this report to be signed on its behalf by the
undersigned hereunto duly authorized.


                                  FRONTIER NATURAL GAS CORPORATION



Dated:  October 11, 1996


                                     /s/ DAVID W.BERRY
                                  ---------------------------------
                                    David W. Berry, President

<PAGE>
 
EXHIBIT 10.1

                              EXCHANGE AGREEMENT

     THIS AGREEMENT is made and entered into as of September 1, 1996, by and
between OXY USA INC., a Delaware corporation (hereinafter referred to as "OXY"),
with a mailing address at P. O. Box 300, Tulsa, Oklahoma 74102, and FRONTIER,
INC., a corporation (hereinafter Frontier Inc. and Frontier Acquisition
Corporation shall be collectively  referred to as "Frontier"), with a mailing
address at One Allen Center, 500 Dallas Street, Suite 2920, Houston, Texas
77002.

                                   RECITALS
                                   --------

     WHEREAS, OXY is the owner of certain oil and gas real property interests
and related tangible assets located in the County of Garvin, State of Oklahoma;
and

     WHEREAS, Frontier is the owner of certain oil and gas real property
interests and related tangible assets located in the County of Major, State of
Oklahoma; and

     WHEREAS, OXY and Frontier desire to convey and exchange their respective
properties, which are like-kind properties pursuant to the terms and conditions
provided in this Agreement and the provisions of Section 1031 of the Internal
Revenue Code of 1986, as amended.

     NOW, THEREFORE, in consideration of the mutual benefits to be derived
herefrom, OXY and Frontier hereby agree as follows:

                           ARTICLE I  - DEFINITIONS
                           ------------------------

1.1  "Assets" shall refer to and include all of Frontier's right, title and
     --------
interest in and to all depths owned and to those real property interests
described in Exhibit B, attached hereto and made a part hereof for all purposes,
and in and to the personal property as described in Paragraph 1.1(e) and all of
OXY's right, title and interest in and to those real property interests
described in Exhibit A, attached hereto and made a part hereof for all purposes,
and in and to the personal property as described in Paragraph 1.1(e) which
interests shall include without limitation the following:

     (a)  Oil, gas and other mineral leases ("Leases"), overriding royalty
          interests and other property interests described in Exhibits A and B,
          insofar and only insofar as such cover and affect the lands described
          in Exhibits A and B;

     (b)  Any rights and obligations derived from or created by unitization,
          pooling or communitization agreements or units formed under or
          pursuant to orders of any governmental authority;

     (c)  All contracts and contractual rights, obligations and interests
          including but not
<PAGE>
 
EXCHANGE AGREEMENT
PAGE 2
          limited to unit agreements, farmout or farmin agreements, operating or
          joint operating agreements, production sales contracts [but, as to the
          interests described on Exhibit A, excluding that certain agreement for
          the Purchase and Sale of Crude Oil executed the 31st day of August,
          1983, by and between Occidental Petroleum Corporation, et al and CITGO
          Petroleum Corporation, et al, (the "CITGO Contract")], gas purchase
          contracts, processing contracts, gas balancing agreements, only
          insofar as such are assignable and relate to the interests described
          in Exhibits A and B. Such contracts shall hereinafter be referred to
          as "Existing Contracts";

     (d)  Surface fee interests, surface use agreements, easements, permits and
          rights-of-way and similar rights and interests applicable to or used
          or useful in connection with any or all of the interests described in
          Exhibits A and B;

     (e)  All wells, equipment, facilities and personal property (excluding
          vehicles) located on the lands described in Exhibits A and B, and used
          solely and directly in connection with the production, operation,
          treatment or transportation of oil and/or gas from those certain
          depths and lands described in Exhibits A and B, including, but not
          limited to, pumping equipment, storage facilities, pipelines,
          treatment equipment, meter stations, salt water disposal wells,
          separators, compressors, tanks, tank batteries and other fixtures;

     (f)  The oil, gas of any kind and nature, other hydrocarbons and other
          minerals in, on and produced from and after the Effective Date hereof;
          and

     (g)  Copies of original records, files, reports and other written material
          relating directly to the interests described in Exhibits A and B
          including, but not limited to, lease files, property records, contract
          files, operation files, maintenance files, development geological
          records, contractor files, financial records, NGPA filings and
          records, landowner files, reports to regulatory agencies.

     (h)  Notwithstanding the foregoing, the definition of Assets shall not
          include any record, file, written document, or any other document,
          information or tangible thing that is identified as being subject to:
          (1) any confidentiality agreement (unless transfer is otherwise
          permitted thereunder), (2) any agreement to inhibit or restrict the
          transfer of such document, information or tangible thing, or (3) any
          claim of attorney work product or attorney client privilege.

    (i)   Notwithstanding the foregoing or any other provision of this
          Agreement, Frontier specifically excludes from this exchange, all of
          its rights to pursue its damage claims against any party as such
          rights relate to the drilling of the Redgate #1-29 well, API No. 093-
          23920 in G29, T23N, R16W, Major County, Oklahoma which retained rights
          shall be contract, tort, trespass and related rights, provided
<PAGE>
 
EXCHANGE AGREEMENT
PAGE 3

          however, that such retained rights shall not include mineral, working
          interest or real property rights all of which shall be conveyed to
          OXY.


1.2  "Assignee" refers to the party hereto which will own the Assets after the
      --------
Effective Date: namely, Frontier  is the Assignee with regard to the Assets
described on Exhibit A and OXY is the Assignee with regard to the Assets
described on Exhibit B.

1.3  "Assignor" refers to the party assigning its rights in the Assets as of
      --------
the Effective Date: namely Frontier is the Assignor with regard to the Assets
described on Exhibit B, and OXY is the Assignor with regard to the Assets
described on Exhibit A.

1.4  "Effective Date."  Only in the event Closing occurs, the effective date
      --------------
of the exchange contemplated herein shall be September 1, 1996,  7:00 a.m. local
time where the Assets are located .

1.5  "Title Defects"  shall mean any material encumbrance, encroachment,
      -------------
irregularity, defect in, or objection to Assignor's title to the Assets, which,
based upon petroleum industry standards for the area in which the affected
property is located, alone or in combination with other defects, would
unreasonably interfere with Assignee's use and enjoyment of the Assets as
currently used.  "Title Defect" shall also mean the inability of Assignor to
assign to Assignee at least the royalty interest in the Assets and/or at least
the net revenue interest in the Assets and the cost bearing working interest in
the Assets than those undivided percentage interests set forth in Exhibit A with
respect to the Assets assigned by OXY, and Exhibit B with respect to the Assets
assigned by Frontier.

                        ARTICLE II - EXCHANGE OF ASSETS
                        -------------------------------

2.1  ASSIGNMENT BY OXY.  Subject to the other provisions of this Agreement,
     -----------------                                                     
OXY shall exchange with and assign to Frontier all of OXY's right, title and
interest in and to the Assets, as defined above and as described in Exhibit "A",
in the form of assignment attached hereto as Exhibit "A-1".

2.2  ASSIGNMENT BY FRONTIER.  Subject to the other provisions of this
     ----------------------                                          
Agreement, Frontier shall exchange with and assign to OXY all of  Frontier's
right, title and interest in and to the Assets, as defined above and as
described in Exhibit "B", in the form of assignment attached hereto as Exhibit
"B-1".



                          ARTICLE III - CONSIDERATION
                          ---------------------------

     The consideration for this Agreement is the mutual exchanges, payments and
assignments between the Parties described herein.
<PAGE>
 
EXCHANGE AGREEMENT
PAGE 4

As additional consideration for the Assets described in Exhibit A, OXY agrees to
pay at Closing to Frontier Two Million Eight Hundred Forty Thousand Dollars
($2,840,000).  This additional consideration shall be paid at Closing to
Frontier, at Frontier's direction, by wire transfer of immediately available
funds or company check.

As further Consideration, Assignee hereby agrees, as of the Effective Date, to
assume, perform and comply with all of the provisions and obligations (expressed
or implied), that are attributable to the Assets, including without limitation
the following:

     (a)  All the terms and conditions of the Leases and of the contracts,
          agreements and instruments which relate to the Assets, including but
          not limited to, those described in Exhibits A and B.

     (b)  Compliance with any and all laws, ordinances, rules and regulations
          affecting the Assets, and the operation thereof, including but not
          limited to (a) those related to the proper plugging and abandonment of
          all wells, whether currently producing or non-producing, which are
          part of the Assets, or which are thereafter drilled on the Assets, (b)
          those related to removal of all equipment and facilities and to
          restoration of the surface of the lands included in the Assets, and
          (c) those related to inactive or unplugged wells, bonding and
          permitting, and to the use of explosives in shooting or pulling of
          casing and tubing.

            ARTICLE IV - REPRESENTATIONS AND WARRANTIES BY PARTIES
            ------------------------------------------------------

     Each party to this Agreement, in its capacity as Assignor hereunder and
with respect to the Assets for which it is Assignor, hereby makes the following
representations and warranties as of the Closing Date to the Assignee:

4.1  AUTHORIZATION.
     ------------- 

     (a)  Organization and Standing.  Assignor is a corporation duly organized,
          -------------------------                                            
          validly existing and in good standing under the laws of its state of
          incorporation and is duly qualified to acquire and operate the Assets.

     (b)  Corporate Power.  Assignor has the corporate power to enter into and
          ---------------                                                     
          perform this Agreement and to consummate the transactions contemplated
          hereby. The execution, delivery and performance of this Agreement by
          Assignor, and the transactions contemplated hereby, do not violate (i)
          any provision of the articles of incorporation or bylaws of Assignor,
          or (ii) any judgment, order, ruling or decree applicable to Assignor
          as a party in interest.

     (c)  Execution and Delivery.  The execution, delivery and performance of 
          ----------------------                                              
          this Agreement and the consummation of the transactions contemplated
          hereby have
<PAGE>
 
EXCHANGE AGREEMENT
PAGE 5


          been duly and validly authorized by all requisite corporation action
          on the part of Assignor and this Agreement has been duly executed and
          delivered on behalf of Assignor.

     (d)  Validity of Agreement.  This Agreement constitutes a legal, valid and
          ---------------------                                                
          binding obligation of Assignor, enforceable against Assignor in
          accordance with its terms, except that such enforcement may be subject
          to (i) bankruptcy, insolvency, reorganization or other similar laws
          now or hereafter in effect affecting the enforcement of creditors;
          rights generally, and (ii) general principles of equity (regardless of
          whether enforcement is considered in a proceeding in equity or at
          law).

4.2  TITLE.  With regard to the Assets it conveys, except as to otherwise
     -----                                                               
provided herein, ASSIGNOR DOES NOT WARRANT OR REPRESENT, EITHER EXPRESSLY OR BY
IMPLICATION, TITLE TO PROPERTY (REAL OR PERSONAL), THE CONDITION OF ANY WELLS OR
EQUIPMENT OR THE QUANTITY, QUALITY OR CONDITION OF ANY MATERIAL OR EQUIPMENT OR
ITS FITNESS FOR USE OR THE SUITABILITY FOR USE OF SAME IN WHOLE OR IN PART.
ASSIGNOR DISCLAIMS ANY IMPLIED WARRANTY OF MERCHANTABILITY OF ANY PERSONAL
PROPERTY OR OF THE FITNESS OF ANY PERSONAL PROPERTY FOR ANY PURPOSE, AND
ASSIGNEE AGREES THAT ANY PERSONAL PROPERTY IS SOLD "AS IS" AND "WHERE IS".
ASSIGNOR DOES NOT MAKE ANY REPRESENTATION OR WARRANTY, EXPRESS OR IMPLIED, AT
COMMON LAW, BY STATUTE OR OTHERWISE RELATING TO THE ACCURACY OR COMPLETENESS OF
ANY INFORMATION, DATA OR OTHER MATERIALS (WRITTEN OR ORAL) HERETOFORE OR
HEREAFTER  FURNISHED TO ASSIGNEE BY OR ON BEHALF OF ASSIGNOR.

4.3  REPRESENTATIONS.
     --------------- 

     (a)  Royalties.  To the best of Assignor's knowledge, as of the Closing
          ---------
          Date, all royalties, rentals, and other payments due under all leases
          relating to the Assets have been properly and timely paid.

     (b)  Third Party Waivers.  To the best of Assignor's knowledge, except for
          -------------------                                                  
          consents from governmental entities customarily acquired subsequent to
          the assignment, all requisite third party consents to assign or third
          party waivers to the assignment, including any preferential rights of
          purchase and waivers thereto, have been secured by Assignor or will
          have been secured by the date of Closing.

     (c)  Litigation, Proceedings and Claims. To the best of Assignor's
          ----------------------------------
          knowledge, there are no actions, suits or arbitration proceedings
          pending before any court or governmental agency that would result in
          impairment or loss of Assignor's title to the Assets or would
          otherwise materially and adversely affect the Assets.
<PAGE>
 
EXCHANGE AGREEMENT
PAGE 6

     (d)  Compliance with Laws.  To the best of Assignor's knowledge, as of the
          --------------------                                                 
          Effective Date Assignor has complied, in all material respects, with
          all rules, laws, regulations, ordinances and orders of all local,
          tribal, state and federal governmental bodies, authorities and
          agencies having jurisdiction over the Assets.

     (e)  Mortgages and Other Instruments.  To the best of Assignor's knowledge,
          -------------------------------                                       
          neither the performance of this Agreement, nor the consummation of the
          transactions contemplated by this Agreement, will cause a breach of
          any of the terms and conditions of any agreement or other instrument
          to which Assignor is a party or by which it is bound or result in the
          creation or imposition of any lien upon any of the Assets, or the
          production of oil, gas or other minerals from the Assets.

     (f)  Brokers.  Assignor has not incurred any liability, contingent or
          -------                                                         
          otherwise, for brokers' or finders' fees relating to the transactions
          contemplated by the Agreement for which Assignee shall have any
          responsibility whatsoever.

     (g)  Frontier represents that there are no hedge contracts that effect
          title to or affect the value of Assets being conveyed by Frontier.


            ARTICLE V - REPRESENTATIONS AND WARRANTIES BY ASSIGNEE
            ------------------------------------------------------

     Each party in its capacity as Assignee hereunder and with respect to the
Assets for which it is Assignee, represents and warrants to the Assignor of such
Assets:

     (a)  Organization and Standing.  Assignee is a corporation duly organized,
          -------------------------                                            
          validly existing and in good standing under the laws of the state of
          its incorporation and is duly qualified to acquire and operate the
          Assets in the state in which the Assets are located.

     (b)  Corporate Power.  Assignee has the corporate power to enter into and
          ---------------                                                     
          perform this Agreement and the transactions contemplated hereby.
          Subject to rights to consent by governmental entities and required
          notices to and filings with governmental entities where the same are
          customarily obtained or made subsequent to the assignment of oil and
          gas interests and leases, the execution, delivery and performance of
          this Agreement by Assignee and the transactions contemplated hereby
          will not violate (i) any provision of the articles of incorporation or
          bylaws of Assignee, or (ii) any judgement, order, ruling or decree
          applicable to Assignee as a party in interest.

     (c)  Execution and Delivery.  The execution, delivery and performance of
          ----------------------                                             
          this Agreement and the transactions contemplated hereby have been duly
          and validly
<PAGE>
 
EXCHANGE AGREEMENT
PAGE 7

          authorized by all requisite corporate action on the part of Assignee.
          This Agreement has been duly executed and delivered. This Agreement
          does, and such documents and instruments shall, constitute legal,
          valid and binding obligations of Assignee enforceable in accordance
          with their terms.

     (d)  Validity of Agreement.  This Agreement does, and such documents and
          ---------------------                                              
          instruments shall, constitute a legal, valid and binding obligation of
          Assignee, enforceable against Assignee in accordance with its terms,
          except that such enforcement may be subject to (i) bankruptcy,
          insolvency, reorganization or other similar laws now or hereafter in
          effect affecting the enforcement of creditors' rights generally, and
          (ii) general principles of equity (regardless of whether enforcement
          is considered in a proceeding in equity or at law).

     (e)  Licenses and Permits.  At or prior to Closing, Assignee shall obtain
          --------------------                                                
          or satisfy Assignor that it will obtain all licenses, bonds, permits
          and other approvals which to the best of Assignee's knowledge are
          required to be obtained by it to succeed Assignor as owner of its
          Assets.

     (f)  Assumption of Obligations.  Assignee shall assume, and agrees and
          -------------------------                                        
          covenants to perform, all the express and implied covenants, duties
          and obligations of Assignor relating to its Assets which shall accrue
          under applicable leases, contracts or agreements or are required by
          applicable laws and regulations.

     (g)  Further Distribution.  Assignee is acquiring the Assets for its own
          --------------------                                               
          account and not with view to, or for offer or resale in connection
          with, a distribution or transfer thereof within the meaning of the
          Securities Act of 1933 and the rules and regulations pertaining to it
          or in violation of any applicable federal and state securities laws.

     (h)  Brokers.  Assignee has not incurred any liability, contingent or
          -------                                                         
          otherwise, for brokers' or finders' fees relating to the transactions
          contemplated by this Agreement for which Assignor shall have any
          responsibility whatsoever.

               ARTICLE VI - CONDUCT OF BUSINESS PRIOR TO CLOSING
               -------------------------------------------------

6.1  OPERATION OF ASSETS.  Prior to the Closing Date or Effective Date,
     -------------------                                               
whichever occurs later, each Assignor agrees, unless specifically waived by
Assignee in writing, to:

     (a)  Maintain and operate the Assets, to the extent Assignor is the
          operator, or to use reasonable efforts to cause the Assets to be
          maintained and operated by the operator thereof, in a good and
          workmanlike manner and in substantially the same manner as Assignor
          has theretofore operated the same, to the extent the interest to be
          conveyed hereunder is a cost bearing working interest and Assignor is
          the operator;
<PAGE>
 
EXCHANGE AGREEMENT
PAGE 8

     (b)  To the extent that the interest to be conveyed hereunder is a cost
          bearing working interest, Assignor shall pay timely all appropriate
          costs and expenses incurred by it in connection with the Assets;

     (c)  Not enter into any material new agreements or amend or terminate any
          material existing agreements relating to the Assets; and

     (d)  Not encumber, sell, or otherwise dispose of any of the Assets other
          than in the ordinary course of business.

Insofar as Assignor has the right of access and egress to and across the Assets,
said Assignor shall afford Assignee and its representatives access to the Assets
operated by the Assignor and Assignor shall use reasonable efforts to cause the
operator of any portion of the Assets not operated by Assignor to allow Assignee
access to such portion of such Assets and the records of such operator, all at
Assignee's risk and expense.

6.2  INDEPENDENT EVALUATION AND TITLE REVIEW.  As soon as possible after
     ---------------------------------------                            
execution of this Agreement, each party shall allow the other full access during
normal business hours to all records and documents in Assignor's possession
affecting title to the Assets and shall allow the other to copy such
information.  It is each Assignee's responsibility to satisfy itself as to the
condition of the Assets and Assignor's title thereto prior to Closing of the
subject transaction.  Each Assignee will be afforded the opportunity to inspect
the Assets and to examine the records of Assignor at Assignor's offices with
respect to the Assets and will be afforded access to all information in
Assignor's possession with respect to the Assets.  ASSIGNEE ACKNOWLEDGES THAT
ASSIGNOR HAS MADE NO REPRESENTATIONS, VERBAL OR OTHERWISE, OR WARRANTIES AS TO
THE ACCURACY OR COMPLETENESS OF SUCH INFORMATION, OR AS TO ASSIGNOR'S TITLE TO
THE ASSETS, AND, IN ENTERING INTO AND PERFORMING THIS AGREEMENT, ASSIGNEE HAS
RELIED AND WILL RELY SOLELY UPON ITS INDEPENDENT INVESTIGATION OF, AND JUDGEMENT
WITH RESPECT TO, THE ASSETS, THEIR VALUE AND ASSIGNOR'S TITLE THERETO.

6.3  CASUALTY LOSSES.  If prior to the Closing Date any facility or equipment
     ---------------                                                         
included within the Assets to be transferred by Assignor is damaged or destroyed
by fire, flood, storm or other casualty (hereinafter called "Casualty Loss"),
Assignor shall immediately notify Assignee.  Assignee shall have the option to
proceed with the exchange under the terms and conditions of this Agreement,
renegotiate the exchange, or to terminate the exchange without any further
liability to either party.  Should Assignee elect to proceed with the exchange,
Assignee shall receive any insurance proceeds payable to Assignor with respect
to such Casualty Loss.

6.4  HART-SCOTT-RODINO ACT.  Each party shall make all filings required of it
     ---------------------                                                   
under the 
<PAGE>
 
EXCHANGE AGREEMENT
PAGE 9

Hart-Scott-Rodino Act of 1976, and rules and regulations promulgated pursuant
thereto (the "HSR Act"), by virtue of the exchange contemplated hereunder.

                  ARTICLE VII - ADJUSTMENT OF EXCHANGE VALUES
                  -------------------------------------------

     On or before ten (10) days prior to Closing, the party to whom an Asset is
to be assigned shall deliver to the party transferring such Asset written notice
of any matters which either constitute a Title Defect or cause a breach of the
representations and warranties as set forth in Article IV herein made with
respect to that Asset. The party transferring such Asset, at its sole cost and
expense, may attempt to cure such matters. In the event that party is unable or
chooses not to cure such matter, or in the event of a Casualty Loss as set forth
in Article VI herein, the party receiving the Asset may terminate this Agreement
and all rights and obligations associated therewith, or it may choose to proceed
with the exchange on the terms and conditions set forth in this Agreement, or
renegotiate the exchange with the other party. In no event shall either party
ever be required to contribute cash to make up losses in value occasioned by
Title Defect or Casualty Loss.

The parties agree that this Article VII shall provide the sole remedy for
addressing any Title Defect or any breach of the representations and warranties
contained in Article IV.  At Closing hereunder, except as otherwise agreed to in
writing, the parties shall be conclusively deemed to have waived any and all
Title Defects or breaches of the representations and warranties contained in
Article IV hereof.

       ARTICLE VIII - PROCEEDS, ROYALTY OBLIGATIONS, EXPENSES AND TAXES
       ----------------------------------------------------------------

8.1  ACCOUNTING FOR PRODUCTION AND PROCEEDS OF PRODUCTION.  The right to
     ----------------------------------------------------               
production from or attributable to the Assets shall pass from Assignor to
Assignee as of the Effective Date.  Assignor shall retain ownership and be
entitled to all proceeds from the sale of any oil and plant products in tanks or
storage facilities above the pipeline connections, attributable to the Assets
prior to the Effective Date.  If Assignor should at any time subsequent to the
Closing Date receive from any purchasers of production any proceeds attributable
to any sale of production from the Assets occurring after the Effective Date,
Assignor shall promptly remit all such amounts to Assignee.  Similarly, if
Assignee should at any time after the Closing Date receive any proceeds
attributable to any such sale occurring prior to the Effective Date, Assignee
shall promptly remit the same to Assignor.

8.2  ROYALTY OBLIGATIONS:  EXPENSES.  Assignor shall be responsible for the
     ------------------------------                                        
payment of all royalty obligations, operating expenses and capital expenses
attributable to the Assets prior to the Effective Date, however, Assignor shall
not be responsible for those royalty obligation amounts attributable to the
Assets prior to the Effective Date and which were held in suspense by Assignor
and transferred to Assignee at Closing or through the post closing adjustment
provided for in Article XI.  Assignee shall be responsible for the payment of
all royalty obligations, operating expenses and capital expenses attributable to
the Assets after 
<PAGE>
 
EXCHANGE AGREEMENT
PAGE 10

the Effective Date. Assignee shall also assume full responsibility for the
payment of all funds arising out of production from the Assets which have been
deposited in accordance with various state escrow statutes. At Closing, Assignor
shall furnish a listing of all accounts and funds so held or deposited. Assignee
agrees to and shall indemnify, defend and hold Assignor harmless for all actions
arising out of or in connection with the deposit or disburse ment of said funds.
A party paying any such royalties or expenses which are the responsibility of
the other party shall be entitled to prompt reimbursement upon evidence of such
payment.

8.3  TAXES.  All taxes (other than income taxes or sales taxes) relating to
     -----                                                                 
production of oil, gas and condensate attributable to the Assets prior to the
Effective Date, regardless of the basis therefore, shall be the obligation of
and paid by Assignor, and all taxes relating to such production on or after the
Effective Date shall be the obligation of and paid by Assignee.

8.4  SALES OR TRANSFER TAXES.  The consideration provided for hereunder is net
     -----------------------                                                  
of any applicable sales taxes or other transfer taxes in connection with the
exchange of the Assets.  Assignee shall be liable for any sales tax or other
transfer tax, as well as any applicable conveyance, transfer and recording fee,
and real estate transfer stamps or taxes imposed on the transfer of the Assets
pursuant to this Agreement. Assignee shall indemnify and hold Assignor harmless
with respect to the payment of any such taxes and fees including any interest or
penalties assessed thereon.

8.5  COOPERATION.  Each party shall provide reasonable access during normal
     -----------                                                           
business hours to all relevant documents, data and other information which may
be required by the other party for the purpose of preparing tax returns and
responding to any audit by any governmental entity.  Each party shall cooperate
with all reasonable requests of the other party made in connection with
contesting the imposition of taxes.  Notwithstanding anything to the contrary in
this Agreement, neither party shall be required at any time to disclose to the
other party any tax returns or other confidential tax information.

8.6  JOINT BILLING AUDITS:  CREDITS.  To the extent that the interest to be
     ------------------------------                                        
conveyed pursuant hereto is a cost bearing working interest, Assignor shall be
responsible for and entitled to the settlement of all joint billing audits which
relate to accounting periods prior to Effective Date.  Assignee shall be
responsible for and entitled to the settlement of all joint billing audits which
relate to accounting periods after the Effective Date.  Any amounts and credits
received by Assignee after the Effective Date attributable to expenses paid
prior to the Effective Date shall be reimbursed to Assignor by Assignee.

                             ARTICLE IX - CLOSING
                             --------------------

9.1  CONDITIONS TO CLOSING.
     --------------------- 

     (a)  Conditions to Obligations of Assignee.  The obligations of Assignee
          -------------------------------------    
          to be performed at the Closing are subject to the satisfaction of the
          following
<PAGE>
 
EXCHANGE AGREEMENT
PAGE 11

          conditions, any one or more of which may be waived in whole or in part
          by Assignee:

          (i)   Representations and Warranties. The representations of Assignor
                ------------------------------
                set forth in this Agreement shall be true and correct in all
                material respects as of the Closing Date (except as may be
                specifically contemplated hereby).

          (ii)  Performance of Obligations of Assignor.  Assignor shall have
                --------------------------------------                      
                performed in all material respects all conditions required to be
                performed by it under this Agreement prior to or on the Closing
                Date.

          (iii) Necessary Consents and Waivers of Preferential Rights.  Assignor
                -----------------------------------------------------           
                shall have applied for and obtained all material governmental or
                other third party consents or other actions necessary to the
                consummation of the exchange contemplated by this Agreement.

          (iv)  Litigation. No suit or other proceeding shall be pending before 
                ---------- 
                any court or governmental agency seeking to restrain or prohibit
                the exchange contemplated by this Agreement.

          (v)   No Violations. The Closing shall not violate any order or decree
                -------------
                of any court or governmental body having competent jurisdiction.

          (vi)  Liens. The Assets shall be delivered free and clear of any
                -----
                liens, mortgages, security interests, production payments, net
                profits interest or other similar encumbrances by, through and
                under Assignor, and in the event the Assets have an existing
                lien, it will be released prior to Closing.

     (b)  Conditions to Obligations of Assignor.  The obligations of Assignor
          -------------------------------------                              
          to be performed at the Closing are subject to the satisfaction of the
          following conditions, any one or more of which may be waived in whole
          or in part by Assignor:


          (i)   Representations and Warranties. The representations of Assignee
                ------------------------------
                set forth in this Agreement shall be true and correct in all
                material respects as of the Closing Date.

          (ii)  Performance of Obligations of Assignee.  Assignee shall have
                --------------------------------------                      
                performed in all material respects all conditions required to be
                performed by it under this Agreement prior to or on the Closing
                Date.
<PAGE>
 
EXCHANGE AGREEMENT
PAGE 12

          (iii) Litigation.  No suit or other proceeding shall be pending before
                ----------                                                      
                any court or governmental agency seeking to restrain or prohibit
                the exchange contemplated by this Agreement. Upon receipt,
                Assignee shall also execute and acknowledge the conveyance
                documents.

          (iv)  No Violations. The Closing shall not violate any order or decree
                -------------
                of of any court or governmental body having competent
                jurisdiction .

9.2  DATE AND PLACE OF CLOSING.  The Closing of the exchange of the Assets
     -------------------------                                            
shall take place at the offices of OXY at such time and date as may be agreed
upon by Frontier and OXY (the "Closing Date"), but not later than October 15,
1996, unless otherwise mutually agreed to in writing by the parties.

9.3  CLOSING OBLIGATIONS.  At the Closing the following events shall occur,
     -------------------                                                   
each being a condition precedent to the others and each being deemed to have
occurred simultaneously with the others:

     (a)  Assignor shall execute, acknowledge and deliver to Assignee conveyance
          documents substantially in the form set forth in Exhibits A-1 or B-1
          to this Agreement as to all Assets and such other instruments of
          transfer and assignment necessary to convey to Assignee or its
          subsidiary the Assets in the manner contemplated by this Agreement.
          Upon receipt, Assignee shall also execute and acknowledge the
          conveyance documents and shall file such documents for recording in a
          timely fashion with the proper authorities in the appropriate
          counties. Thereafter, Assignee shall provide Assignor with all
          recording information.

     (b)  Assignor shall deliver to Assignee exclusive possession of the Assets,
          and Assignee shall take possession of the Assets, effective as of the
          Effective Date.

     (c)  Assignor and Assignee shall execute, acknowledge, and deliver transfer
          orders or letters in lieu thereof directing all purchasers of
          production to make payments of proceeds attributable to production
          from the Assets to Assignee.

     (d)  Assignor and Assignee shall execute, acknowledge and deliver such
          other instruments and take such other action as may be necessary to
          carry out their respective obligations under this Agreement,
          including, but not limited to, assignment of Operating Rights (if
          applicable) on forms acceptable to the appropriate governmental
          entity.

     (e)  OXY shall pay to Frontier (as directed) the additional consideration
          provided for in Article III.
<PAGE>
 
EXCHANGE AGREEMENT
PAGE 13

                     ARTICLE X - TERMINATION OF AGREEMENT
                     ------------------------------------

     (a)  In addition to termination pursuant to Section 6.3 or Article VII,
          this Agreement may be terminated at any time prior to the Closing Date
          by:

          (i)   Either party hereto, if consummation of the transactions
                contemplated hereby would violate any non-appealable final order
                of any court or governmental body having competent jurisdiction;

          (ii)  Either party hereto, if prior to Closing, any legislation which
                would have the effect of prohibiting or making unlawful the
                acquisition or ownership of the Assets by Assignee or the
                conveyance or trade of the Assets by Assignor has been enacted
                into law .

     (b)  This Agreement shall terminate in the event either party fails to
          fulfill the conditions of Article IX, which give rise to the other
          parties' obligation to close, unless such other party waives the
          unfulfilled conditions.

     (c)  In the event of the termination of this Agreement pursuant to the
          provisions of this paragraph, this Agreement shall become void and
          have no effect, without any liability on the part of either party or
          any of its directors, officers, partners, employees or stockholders.

                    ARTICLE XI - OBLIGATIONS AFTER CLOSING
                    --------------------------------------

11.1 POST-CLOSING ADJUSTMENTS.  Within one hundred twenty (120) days after
     ------------------------                                             
Closing, a final settlement statement will be prepared by each party of the
Assets assigned by that party and submitted to the other, showing income and
expenses for the Assets between the Effective Date and Closing Date and other
charges and credits provided in this Agreement.

     (a)  Assignor shall be credited with:

          (i)   The value of all merchantable oil and plant products above the
                pipeline connections in tanks and storage facilities at the
                Effective Date that is credited to Assignor's net revenue or
                royalty interest in the Assets, such value to be the actual
                price received by Assignee as of the Effective Date, less any
                taxes withheld properly by the purchaser of such.

          (ii)  The amount of all costs and expenses, including, without
                limitation, rentals and other charges, ad valorem and other
                taxes based upon or measured by the ownership of property or the
                production of hydrocarbons or the receipt of proceeds therefrom,
                expenses paid under applicable operating
<PAGE>
 
EXCHANGE AGREEMENT
PAGE 14

                agreements and, in the absence of an operating agreement,
                expenses of the sort customarily billed under such agreements,
                not including income taxes, paid by or on behalf of Assignor, in
                connection with the operation of the Assets for work performed
                during the period after the Effective Date.

          (iii) An amount equal to all prepaid expenses attributable to the
                Assets that are paid by or on behalf of Assignor prior to or
                after the Closing Date and that are, in accordance with
                generally accepted accounting principles, attributable to the
                period after the Effective Date, including without limitation,
                prepaid ad valorem, property, production, severance, and similar
                taxes (but not including income taxes) based upon or measured by
                the ownership of property or the production of hydrocarbons on
                the receipt of proceeds therefrom. Any refund of ad valorem tax
                attributable to the period before the Effective Date received by
                Assignee shall be credited to Assignor.

     (b)  Assignee shall be credited with:

          (i)   Proceeds net of royalties received by Assignor that are, in
                accordance with generally accepted accounting principles,
                attributable to the Assets for the period of time after the
                Effective Date.

          (ii)  The amount of all costs and expenses, including, without
                limitation, rentals and other charges, ad valorem, property,
                production, excise, severance, windfall profit, and other taxes
                based upon or measured by the ownership of property or the
                production of hydrocarbons or the receipt of proceeds therefrom,
                expenses paid under applicable operating agreements and, in the
                absence of an operating agreement, expenses of the sort
                customarily billed under such agreements, not including income
                taxes, paid by or on behalf of Assignee, in connection with the
                operation of the Assets for work performed during the period
                prior to the Effective Date.

          (iii) The amount attributable to royalty obligations held in suspense
                by Assignor and attributable to the Assets prior to the
                Effective Date.

     (c)  In addition to the matters mentioned above, the final settlement
          statement shall include any other debits and credits, either cash or
          accrued, but excluding income and franchise taxes, which under
          generally accepted accounting principles would reflect transfer of
          ownership of the Assets on the Effective Date.

     (d)  The net amount to be paid by the owing party shall be paid within
          thirty (30) days after receipt of the final settlement statement.
          Assignee shall have the right
<PAGE>
 
EXCHANGE AGREEMENT
PAGE 15

          for a period of one hundred twenty (120) days from the date of the
          final settlement statement in which to audit the matters covered
          thereby.

     (e)  In the event Assignee and Assignor are unable to mutually agree upon
          the amount of the settlement statement, an audit shall be conducted by
          an accounting firm on which the parties mutually agree. Assignee and
          Assignor agree to be bound by the findings of such audit, insofar as
          the final settlement statement amount is concerned, and each shall
          bear one half of all expenses associated with such audit.

11.2 FURTHER ASSURANCES. After Closing, Assignor agrees to execute and deliver
     ------------------
to Assignee all such instruments, notices, division or transfer orders, and
other documents, and to do all such other acts not inconsistent with this
Agreement as may reasonably be necessary or advisable to carry out its
obligations under this Agreement or to more fully assure Assignee, its
successors and assigns, of the respective rights, titles, interests and estates
herein provided to be assigned and conveyed by Assignor to Assignee at Closing.

11.3 EXISTING OBLIGATIONS.
     -------------------- 

     (a)  Existing Contracts. The Exchange Property will be conveyed subject to
          ------------------
          any and all Existing Contracts, as well as any and all other
          agreements pertaining thereto which are of record or of which Assignee
          has actual notice. To the extent of the interest acquired by Assignee
          hereunder, Assignee agrees to and shall assume and be responsible for
          all obligations of Assignor under such Existing Contracts and other
          agreements as of the Effective Date. Should any such agreement provide
          for a preferential right to purchase or require prior consent to
          assign, then the obligation of Assignee to purchase the property
          affected thereby shall be subject to Assignor obtaining such waiver or
          consent prior to the Closing Date.

     (b)  OXY and Frontier agree that this exchange of Assets is subject to and
          OXY does hereby reserve the Citgo Contract, and the option, hereby
          exercised and exercisable at any time and from time to time after the
          Effective Date, of purchasing or marketing for the benefit of
          Frontier, all of the share of oil produced from or allocated to the
          Assets shown on Exhibit "A" applicable to the interest therein
          acquired by Frontier hereunder at the price provided in the Citgo
          Contract.

                         ARTICLE XII - INDEMNIFICATION
                         -----------------------------

12.1 Assignee shall, (i) at the Effective Time assume, and be responsible for
and comply with all duties and obligations of Assignor, express or implied, with
respect to the interests, including, without limitation, those arising under or
by virtue of any lease, contract, agreement, 
<PAGE>
 
EXCHANGE AGREEMENT
PAGE 16

document, permit, applicable statute or rule, regulation or order of any
governmental authority (specifically including, without limitation, any
governmental request or requirement to plug, re-plug and/or abandon any well of
whatsoever type, status or classification, or take any clean-up or other action
with respect to the property or premises) and (ii) defend, indemnify and hold
Assignor harmless from any and all claims in connection therewith, except any
such claims arising out of, resulting from, or relating to the ownership or
operation of the interests by Assignor prior to the Effective Time.

12.2 Assignee shall defend, indemnify and hold Assignor harmless from any and
all claims in favor of any person, corporation, partnership, governmental or
regulatory agency, or other legal entity for personal injury; death or damage to
property or to the environment, or for any other relief, arising directly or
indirectly from, or incident to, the use, occupation, operation, maintenance or
abandonment of any of the interests, or condition of the property or premises,
whether latent or patent, resulting from or arising out of the conditions,
actions or inactions from and after the Effective Time.

12.3 Assignor shall (i) be responsible for any and all claims arising out of
the production or sale of hydrocarbons from the interests -- or the proper
accounting or payment to parties for their interests therein -- insofar as such
claims relate to periods of time prior to the Effective Time and (ii) defend,
indemnify and hold Assignee harmless from any and all such claims.  Assignee
shall be responsible for all of said types of claims insofar as they relate to
periods of time from and after the Effective Time, and shall defend, indemnify
and hold Assignor harmless therefrom.

12.4 For a period of one year after the Effective Time, Assignor shall defend,
indemnify and hold Assignee harmless from any and all claims in favor of any
person, corporation, partnership, governmental or regulatory agency, or other
legal entity for personal injury, death or damage to property or the
environment, or for any other relief, arising directly or indirectly from, or
incident to, the use, occupation, operation, maintenance or abandonment of any
of the interests or condition of the property or premises, whether latent or
patent, resulting from or arising out of conditions, actions or inactions prior
to the Effective Time.

12.5 Notwithstanding any other provision contained herein to the contrary,
Assignee acknowledges that the Assets have been utilized for the purpose of
exploration, production and development of oil and gas, and that Assignee has
been informed and is aware that oil and gas producing formations can contain
naturally occurring radioactive material (NORM) and that some oil field
production equipment and/or facilities may contain asbestos and/or NORM.
Assignee has inspected the property and premises and satisfied itself as to
their physical and environmental condition, both surface and subsurface.

12.6 In addition to provisions 12.1 and 12.2 above, to the extent that the
interest  received is, or may become, a cost bearing working interest Assignee
agrees to defend, indemnify and hold harmless Assignor and its affiliated
companies, and its and their officers, directors, 
<PAGE>
 
EXCHANGE AGREEMENT
PAGE 17

agents, and employees, from and against all losses, costs, claims, demands,
suits, liability and expense with respect to the Assets which arise out of or
relate to Assignee's ownership and/or operation of such Assets.

                         ARTICLE XIII - MISCELLANEOUS
                         ----------------------------

13.1 INTENT.  It is the intent of OXY to assign and of Frontier to receive all
     ------                                                                   
of OXY's interests in those Assets described in Exhibit "A".  It is the intent
of Frontier to assign and of OXY to receive all of Frontier's interests in those
Assets described in Exhibit "B".  In the event that any interests owned by
Assignor in such properties are omitted or incorrectly described, the parties
agree to execute the documents necessary to effect the intent stated herein.

13.2 IMBALANCES.  Assignee has made an independent investigation into the gas
     ----------                                                              
imbalances and has taken such imbalances into consideration in this Exchange
Agreement.  Assignee shall assume all of Assignor's rights, duties, benefits,
obligations or liability for any production imbalances relating to the Assets
transferred as of the Effective Date.  In the event that Assignor's gas
production, if any, from any of the Assets is out of balance, Assignee shall
acquire the Assets subject to such overproduction or underproduction and no
adjustment shall be made.  In the case of Assets in which Assignor is
underproduced, Assignee shall acquire all of Assignor's rights to recoup such
underproduction, whether pursuant to a gas balancing agreement or otherwise,
subject to applicable royalty and tax burdens.  In the case of Assets in which
Assignor is overproduced, Assignee shall acquire the Assets subject to, and
Assignee shall indemnify Assignor with regard to, the obligation to balance,
either in kind or in cash, the gas production with the underproduced parties in
the Assets. In the event Assignor has received payment for gas not actually
taken under a gas sales contract's "take-or-pay" or similar provision, which
will obligate Assignee to deliver gas at some future time from the Assets
without receiving full payment therefor or will require payment of such "take-
or-pay" payment, an adjustment will be made between the parties by the amount of
such "take-or-pay" payment.

13.3 INTEGRATION:  AMENDMENT AND MODIFICATION.  Except as expressly set forth
     ----------------------------------------                                
herein, neither of the parties makes to the other any representation or
warranty, whether expressed or implied, of any kind whatsoever. This Agreement
may not be modified, supplemented or changed in any respect except by a writing
duly executed by both parties hereto.

13.4 DESCRIPTION HEADINGS.  The headings of the paragraphs and subparagraphs
     --------------------                                                   
of this Agreement are inserted for convenience only and shall not constitute a
part hereof.

13.5 GOVERNING LAW.  THE PARTIES HEREBY AGREE THAT THIS AGREEMENT SHALL BE
     -------------                                                        
GOVERNED BY AND CONSTRUED IN ACCORDANCE WITH THE LAWS OF THE STATE OF OKLAHOMA.
<PAGE>
 
EXCHANGE AGREEMENT
PAGE 18

13.6   BINDING EFFECT:  ASSIGNMENT.  This Agreement shall be binding upon and
       ---------------------------                                           
shall inure to the benefit of and be enforceable by each of the parties, and
their successors and permitted assigns.  This Agreement shall not be assigned
prior to the Closing Date by either party hereto without the consent of the
other, except that either party may assign its rights hereunder to any
subsidiary or affiliate.

13.7   REMOVAL OF SIGNS.  In the case of Assignor-operated properties, Assignee
       ----------------                                                        
shall remove Assignor's name from the property on or as soon as possible after
the actual closing date.  Within ten (10) days of the Closing Date, Assignee
shall post its own signs in compliance with applicable state regulations.  In
the event Assignee fails to do so, Assignor's representatives shall have full
access to the property for such purpose.

13.8   NOTICES.  All notices, disclosures or other information which are
       -------                                                          
required or permitted hereunder shall be in writing and shall be delivered as
follows:

  FRONTIER'S MAILING ADDRESS:              OXY'S MAILING ADDRESS:
  ---------------------------              ----------------------
  Frontier, Inc.                           OXY USA Inc.
  2960 One Allen Center                    P. O. Box 300
  500 Dallas                               Tulsa, Oklahoma, 74102  
  Houston, Texas 77002

13.9   COUNTERPARTS.  This Agreement may be executed in any number of
       ------------                                                  
counterparts and each such counterpart hereof shall be deemed to be an original,
and all of which together shall constitute one and the same instrument. This
Agreement shall not be binding on any named party until it is signed by or
validly on behalf of all named parties and, where applicable, their spouses.

13.10  TAXES.
       ----- 

       (a)  Neither party makes any warranty of any particular tax treatment
            which might be afforded the other party under this Agreement.

       (b)  It is the intention of the parties that the transactions
            contemplated by this agreement shall constitute a like-kind exchange
            in accordance with Section 1031 of the Internal Revenue Code of 1986
            ("IRC").

       (c)  To the extent this transaction constitutes an applicable asset
            acquisition for purposes of IRC Section 1060, Assignee and Assignor
            agree to confer and cooperate in the preparation and filing of such
            reports and/or information as may be required by law or regulation.

       (d)  Assignor represents that the Assets are not subject to any tax
            partnership
<PAGE>
 
EXCHANGE AGREEMENT
PAGE 19

            agreement or provisions requiring a partnership income tax
            return to be filed under Subchapter K of Chapter 1 of the IRC.

       (e)  Assignor represents that none of the Assets are subject to an
            agreement to use the annual method of gas balancing as described in
            Income Tax Regulation Section 1.761-2(d).

13.11  SEVERABILITY.  If any provision of this Agreement is held invalid, the
       ------------                                                          
remainder of the Agreement shall not be affected thereby unless the effect
thereof would be to materially alter the burdens or benefits intended by the
parties by the express language of this Agreement.

13.12  NO PARTNERSHIP CREATED.  The parties do not intend that this Agreement
       ----------------------                                                
create (and it shall not be construed to create) a joint venture, partnership or
any type of association.  No party is authorized hereby to act as agent or
principal for any other party with respect to any matter related hereto.

13.13  FILES AND RECORDS.  Within thirty (30) days after the Closing Date,
       -----------------                                                  
Assignor shall deliver to Assignee copies of all material documents in
Assignor's possession pertaining to the Assets conveyed, except proprietary data
and documents subject to the attorney-client privilege.  For a period of two (2)
years after the date of Closing, Assignee will retain the books, records, and
files of Assignor delivered to it pursuant hereto and will make such books,
records, and files available to Assignor upon reasonable notice, at Assignee's
headquarters (or at such other location in the United States as Assignee may
designate in writing to Assignor), at reasonable times and during regular office
hours.

13.14  SURVIVAL OF OBLIGATIONS.  This Agreement is intended, in part, to
       -----------------------                                          
evidence the continuing rights and obligations of the parties following Closing
under this Agreement. Accordingly, except for the representations and warranties
of the parties, all of the covenants, agreements and other obligations of the
parties expressed herein are hereby expressly made to survive Closing of the
transactions contemplated hereby,.

     IN WITNESS WHEREOF, this Exchange Agreement has been executed this 27th day
of September, 1996.


                                OXY USA INC.

                                By     /s/ Gary C. Timmermann
                                -----------------------------------------------
                                Gary C. Timmermann, Attorney-in-Fact
<PAGE>
 
EXCHANGE AGREEMENT
PAGE 20
                                FRONTIER, INC.

                                By     /s/ David B. Christofferson
                                   -------------------------------
                                Title:  Executive Vice President
                                       -------------------------

                                FRONTIER ACQUISITION CORPORATION

                                By:     /s/ David B. Christofferson
                                    --------------------------------
                                Title:  Executive Vice President
                                       -----------------------------
                                                  President

                                ACKNOWLEDGEMENT


STATE OF OKLAHOMA     )
                      )SS
COUNTY OF TULSA       )

  The foregoing instrument was acknowledged before me this 27th day of September
1996, by Gary C. Timmermann, as Attorney-in-Fact on behalf of OXY USA Inc.

My Commission Expires:

March 12, 1998                            /s/ Linda Jefferson
                                       -----------------------------------
                                                             Notary Public


STATE OF OKLAHOMA     )
                      )SS
COUNTY OF TULSA       )

  The foregoing instrument was acknowledged before me this 27th day of
September, 1996 by David B. Christofferson of Frontier, Inc. on behalf of said
corporation.


My Commission Expires:

March 12, 1998                            /s/ Linda Jefferson
                                       -----------------------------------
                                                             Notary Public
<PAGE>
 
EXHIBIT "A"  -  Attached to and made a part of Exchange Agreement dated August
                28, 1996 between OXY USA Inc. and Frontier, Inc.

                              SCHEDULE OF LEASES
                                        
                          WEATHERFORD "A" (7-3591680)
                          ---------------------------
                                   WI: 100%
                                  NRI: 87.5%

  LEASE NUMBER:      63525138/3525138
  DATE OF LEASE:     December 20, 1950
  LESSOR:            Charlotte E. Plaster, now Weatherford
  LESSEE:            Cities Service Oil Company
  RECORDING DATA:    Book 339 Page 10

  DESCRIPTION:       Insofar as lease covers Lot three (3) and Lot four (4)and
                     East Half of the Southwest Quarter (E/2 SW/4), Section 31,
                     Township 4 North, Range 2 West, Garvin Co., Oklahoma

                       HOLLOWAY-WEATHERFORD (7-3540992)
                       --------------------------------
                                   WI: 100%
                                  NRI: 87.5%

  LEASE NUMBER:      63532136/3525138
  DATE OF LEASE:     July 10, 1943
  LESSOR:            T. S. Holloway
  LESS EE:           Harry H. Phillips
  RECORDING DATA:    Book 232 Page 140
 
  DESCRIPTION:       Northwest Quarter of Southeast Quarter, (NW/4 SE/4), North
                     Half of the Southwest Quarter of the Southeast Quarter (N/2
                     SW/4 SE/4), Southeast Quarter of the Southwest Quarter of
                     the Southeast Quarter (SE/4 SW/4 SE/4), Section 31 Township
                     4 North, Range 2 West, Garvin Co., Oklahoma
                     
  LEASE NUMBER:      63525138/3525138
  DATE OF LEASE:     December 20, 1950
  LESSOR:            Charlotte E. Plaster, now Weatherford
  LESSEE:            Cities Service Oil Company
  RECORDING DATA:    Book 339 Page 10

  DESCRIPTION:       Insofar as lease covers Southwest Quarter of the Southwest
                     Quarter of the Southeast Quarter, (SW/4 SW/4 SE/4) Section
                     31 Township 4 North, Range 2 West, Garvin County, Oklahoma
<PAGE>
 
EXHIBIT "A"
PAGE 2
                             BROWN "K" (7-3508880)
                             ---------------------
                                   WI: 100%
                                  NRI: 87.5%

   LEASE NUMBER:     63523198/3523198
   DATE OF LEASE:    December 27, 1946
   LESSOR:           Lillie C. Brown
   LESSEE:           Carl J. O'Hornet
   RECORDING DATA:   Book 268 Page 348
 
   DESCRIPTION:      Northeast Quarter (NE/4), less right-of-way for railroad;
                     North Half of the Northeast Quarter of the Southeast
                     Quarter (N/2 NE/4 SE/4); Southeast Quarter of the Northeast
                     Quarter of the Southeast Quarter (SE/4 NE/4 SE/4) of
                     Section 16 Township 4 North, Range 3 West, Garvin County,
                     Oklahoma, insofar as the above lease covers all rights LESS
                     AND EXCEPT fifty percent (50%) interest from surface down
                     to the base of the Pennsylvania in the South Half of
                     Northeast Quarter (S/2 NE/4), Northwest Quarter of the
                     Northeast Quarter (NW/4 NE/4), and LESS AND EXCEPT sixty-
                     two and a half percent (62.5%) interest in the North Half
                     of the Northeast Quarter of the Southeast Quarter (N/2 NE/4
                     SE/4) from surface to the Base of the Pennsylvania
                     formation; LESS AND EXCEPT rights from the base of the
                     Pennsylvania formation down to 100' below the stratigraphic
                     equivalent of 10,388' in the North Half of the Northeast
                     Quarter of the Southeast Quarter (N/2 NE/4 SE/4) and
                     Southeast Quarter of the Northeast Quarter of the Southeast
                     Quarter (SE/4 NE/4 SE/4), LESS AND EXCEPT rights into the
                     Gibson Sand from 6949' to 7012'.

   LEASE NUMBER:     63531976/3523198
   LEASE DATE:       May 1, 1943
   LESSOR:           Edna Ruth Thompson
   LESSOR:           Harry H. Phillips
   RECORDING DATA:   Book 234 Page 368

   DESCRIPTION:      Southwest Quarter of the Northeast Quarter of the Southeast
                     Quarter (SW/4 NE/4 SW/4) Section 16 Township 4 North, Range
                     3 West, Garvin County, Oklahoma, Insofar as the lease
                     covers a thirty-seven and a half (37.5%) interest from
                     surface to the base of the Pennsylvania formation.
<PAGE>
 
EXHIBIT "A"
PAGE 3
      
                          SCHEDULE OF SURFACE LEASES
                          --------------------------
 
   LEASE NUMBER:     S3503135
   DATE:             March 15, 1965
   LESSOR:           T. S. Holloway
   LESSEE:           Sinclair Oil & Gas Company
   RECORDING DATA:   Book 667 Page 412

   DESCRIPTION:      Northwest Quarter of the Southeast Quarter (NW/4 SE/4)
                     Section 31 Township 4 North, Range 2 West, Garvin Co.,
                     Oklahoma
 
   LEASE NUMBER:     S3500786
   DATE:             October 29, 1963, amended March 19, 1985
   LESSOR:           Samie Leon Weatherford, et ux
   LESSEE:           Cities Service Oil Company
   RECORDING DATA:   Book 636 Page 394

   DESCRIPTION:      Surface of East Half of the Northwest Quarter of the
                     Southeast Quarter (E/2 NW/4 SE/4) and West Half of the
                     Northeast Quarter of the Southeast Quarter of the Southwest
                     Quarter (W/2 NE/4 SE/4 SW/4), Section 31 Township 4 North,
                     Range 2 West, Disposal rights into Weatherford "A" #5 well.
                     Pipeline easement across Lots 3 and Lots 4 and East half of
                     Southwest Quarter (E/2 SW/4) and Southwest Quarter of the
                     Southwest Quarter of the Southeast Quarter (SW/4 SW/4 SE/4)
                     and Southeast Quarter of the Southeast Quarter of the
                     Northwest Quarter (SE/4 SE/4 NW/4) of Section 31 Township 4
                     North, Range 2 West, Garvin Co., Oklahoma


The above described Oil and Gas Leases are subject to the following:

1.   Contract 35-C-223 between Cities Service Oil Company and Erie P.
     Halliburton Co., dated Mar. 31, 1949 covering oil and gas rights in the S/2
     NE/4 Sec 16 T4N R3W, Garvin Co., Oklahoma.

2.   Contract 35-C-223A between Cities Service Oil Company and Erie P.
     Halliburton Company, dated July 12, 1949 covering oil and gas rights in the
     NE/4 SE/4 Section 16 T4N R3W, Garvin Co., Oklahoma.
<PAGE>
 
EXHIBIT "A"
PAGE 4

3.   Contract 35-C-1243 between Erie P. Halliburton and Cities Service Oil
     Company, dated November 15, 1949 covering oil and gas rights down to the
     base of the Pennsylvania Formation in NW/4 NE/4 Sec 16 T4N R3W, Garvin Co.,
     Oklahoma

4.   Oklahoma Corporation Commission Order No. 374953, dated July 1, 1993.

5.   Maysville Gasoline Plant Contract dated October 1, 1947
<PAGE>
 
Exhibit "A-1" -  Attached to and made a part of Exchange Agreement dated August
                 28, 1996 between OXY USA Inc. and Frontier, Inc.


                       ASSIGNMENT OF OIL AND GAS LEASES,
                                      AND
                                 BILL OF SALE

     This Assignment of Oil and Gas Leases  and Bill of Sale, effective as of
September 1, 1996 at 7 a.m., Central Standard Time, ("Effective Date"), is by
and between OXY USA Inc., a Delaware corporation, whose address is P.O. Box 300,
Tulsa, Oklahoma 74102, as "Assignor", and Frontier, Inc., and Frontier
Acquisition Corporation, an Oklahoma Corporation (hereinafter collectively
referred to as "Frontier"), whose address is 2960 One Allen Center, 500 Dallas,
Houston, Texas 77002, as "Assignee".

                             W I T N E S S E T H:

     For valuable consideration, the receipt and adequacy of which are hereby
acknowledged, Assignor hereby grants, sells, conveys, assigns and transfers to
Assignee, effective as of the Effective Date, the following:

     (a)  The interest of Assignor in the oil and gas leases thereunder as
described in Exhibit "A" attached hereto and incorporated by reference;

     (b)  All of Assignor's right, title and interest in and under, or derived
from, all presently existing contracts, agreements and instruments to the extent
they relate to the interest described in Exhibit "A," including, but not limited
to, operating agreements, unitization agreements, communitization and pooling
agreements, agreements for the sale or purchase of oil, gas, casinghead gas or
CO/2/ [but excluding that certain Agreement For The Purchase and Sale of
Domestic Crude Oil executed the 31st day of August, 1983, by and between
Occidental Petroleum Corporation, et al. and CITGO Petroleum Corporation, et al.
(the "CITGO Contract")], all of which are hereinafter collectively referred to
as "Existing Contracts");

     (c)  All of Assignor's right, title and interest in and to all real and
personal property (excluding vehicles), fixtures, appurtenances, easements,
licenses, approvals or authorizations and permits to the extent they directly
relate to the interests described in Exhibit "A," including all wellbores,
associated equipment, surface rights, and lease and unit owned facilities,
pipelines, treatment equipment, salt water disposal wells, compressors, tanks
and tank batteries and other fixtures.

     (d)  To the extent of the interest sold, all of Assignor's right, title
and interest in and to the oil, gas of any kind and nature, other hydrocarbons
and other minerals in, on and produced from or allocated to the leasehold
interest assigned to Assignee from and after the Effective Date hereof.
<PAGE>
 
EXHIBIT "A-1"
PAGE 2

     All of the property and contract rights, titles and interests described
above are hereinafter collectively called the "Assets".

     TO HAVE AND TO HOLD the said Assets unto Assignee, its successors and
assigns, forever subject to the terms, reservations and conditions contained
herein.

     Assignee represents that it has inspected, or has had sufficient
opportunity to inspect, the Assets and the premises and has satisfied itself as
to their physical and environmental condition, both surface and subsurface, and
Assignee has satisfied itself as to the risks and obligations assumed hereunder,
and that Assignee hereby accepts the same in their "AS IS, WHERE IS" condition.
In addition, all of the Assets, whether real or personal, are conveyed without
WARRANTIES OF TITLE OF ANY KIND, EITHER EXPRESS OR IMPLIED, AND WITHOUT
WARRANTIES AS TO CONDITION, MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE.

     Prior to the execution of this Assignment, Assignee has been afforded the
opportunity to examine the records of Assignor at Assignor's offices with
respect to the Assets and has been afforded access to all information in
Assignor's possession with respect to the Assets.  ASSIGNEE ACKNOWLEDGES THAT
ASSIGNOR HAS MADE NO REPRESENTATIONS, VERBAL OR OTHERWISE, OR WARRANTIES AS TO
THE ACCURACY OR COMPLETENESS OF SUCH INFORMATION, OR AS TO ASSIGNOR'S TITLE TO
THE ASSETS, AND, IN ACCEPTING THIS ASSIGNMENT, ASSIGNEE HAS RELIED AND WILL RELY
SOLELY UPON ITS INDEPENDENT INVESTIGATION OF, AND JUDGMENT WITH RESPECT TO, THE
ASSETS, THEIR VALUE AND ASSIGNOR'S TITLE THERETO.

     Assignor does hereby reserve the option to be exercised from time to time
and as often as desired, of purchasing or marketing for the benefit of Assignee
all of the share of oil produced from and/or allocated to the Assets and
applicable to Assignee's interest acquired hereunder at the price provided in
the CITGO Contract.

     Assignor hereby grants and transfers to Assignee, its successors and
assigns, the benefit of and the right to enforce the covenants and warranties,
if any, which Assignor is entitled to enforce with respect to the Assets against
Assignor's predecessors in title.

     This instrument is made pursuant and subject to the terms of that certain
unrecorded Exchange Agreement (the "Agreement") between Assignor and Assignee
executed                            . Said Agreement, and all of the terms and
         ---------------------------
conditions thereof, is hereby incorporated by reference for all purposes. In the
event of a conflict between this Assignment and said Agreement, the Agreement
shall control except as to any warranties of title, as to which this Assignment
shall control.

     This Assignment of Oil and Gas Leases and Bill of Sale is subject to the
terms and provisions of the CITGO Contract.
<PAGE>
 
EXHIBIT "A-1"
PAGE 3

     By acceptance of this Assignment, on and after the Effective Date Assignee
assumes and agrees to pay, perform and discharge all of Assignor's
responsibilities, liabilities and obligations related to the environmental
condition of the Assets.

     Assignee hereby assumes and agrees to perform all duties and obligations of
the Assignor, present, past and future, applicable to the operations or
prescribed in the leases and Existing Contracts covered hereby.

12.1   Assignee shall, (i) at the Effective Time assume, and be responsible for
and comply with all duties and obligations of Assignor, express or implied, with
respect to the interests, including, without limitation, those arising under or
by virtue of any lease, contract, agreement, document, permit, applicable
statute or rule, regulation or order of any governmental authority (specifically
including, without limitation, any governmental request or requirement to plug,
re-plug and/or abandon any well of whatsoever type, status or classification, or
take any clean-up or other action with respect to the property or premises) and
(ii) defend, indemnify and hold Assignor harmless from any and all claims in
connection therewith, except any such claims arising out of, resulting from, or
relatinag to the ownership or operation of the interests by Assignor prior to
the Effective Time.

12.2   Assignee shall defend, indemnify and hold Assignor harmless from any and
all claims in favor of any person, corporation, partnership, governmental or
regulatory agency, or other legal entity for personal injury; death or damage to
property or to the environment, or for any other relief, arising directly or
indirectly from, or incident to, the use, occupation, operation, maintenance or
abandonment of any of the interests, or condition of the property or premises,
whether latent or patent, resulting from or arising out of the conditions,
actions or inactions from and after the Effective Time.

12.3   Assignor shall (i) be responsible for any and all claims arising out of
the production or sale of hydrocarbons from the interests -- or the proper
accounting or payment to parties for their interests therein -- insofar as such
claims relate to periods of time prior to the Effective Time and (ii) defend,
indemnify and hold Assignee harmless from any and all such claims.  Assignee
shall be responsible for all of said types of claims insofar as they relate to
periods of time from and after the Effective Time, and shall defend, indemnify
and hold Assignor harmless therefrom.

12.4   For a period of one year after the Effective Time, Assignor shall in
addition to any other obligation incurred pursuant hereto, defend, indemnify and
hold Assignee harmless from any and all claims in favor of any person,
corporation, partnership, governmental or regulatory agency, or other legal
entity for personal injury, death or damage to property or the environment, or
for any other relief, arising directly or indirectly from, or incident to, the
use, occupation, operation, maintenance or abandonment of any of the interests
or condition of the property or premises, whether latent or patent, resulting
from or arising out of conditions, actions or inactions prior to the Effective
Time.
<PAGE>
 
EXHIBIT "A-1"
PAGE 4

12.5   Notwithstanding any other provision contained herein to the contrary,
Assignee acknowledges that the Assets have been utilized for the purpose of
exploration, production and development of oil and gas, and that Assignee has
been informed and is aware that oil and gas producing formations can contain
naturally occurring radioactive material (NORM) and that some oil field
production equipment and/or facilities may contain asbestos and/or NORM.
Assignee has inspected the property and premises and satisfied itself as to
their physical and environmental condition, both surface and subsurface.

12.6   In addition to provisions 12.1 and 12.2 above, to the extent that the
interest  received is, or may become, a cost bearing working interest Assignee
agrees to defend, indemnify and hold harmless Assignor and its affiliated
companies, and its and their officers, directors, agents, and employees, from
and against all losses, costs, claims, demands, suits, liability and expense
with respect to the Assets which arise out of or relate to Assignee's ownership
and/or operation of such Assets.

     Notwithstanding any other provision contained herein to be contrary,
Assignee acknowledges that the Assets have been utilized for the purpose of
exploration, production and development of oil and gas, and that Assignee has
been informed and is aware that oil and gas producing formations can contain
naturally occurring radioactive material (NORM) and that some oil field
production equipment and/or facilities may contain asbestos and/or NORM.
Assignee has inspected the property and premises and satisfied itself as to
their physical and environmental condition, both surface and subsurface.

     In addition to the two provisions immediately above, Assignee agrees to
defend, indemnify and hold harmless Assignor and its affiliated companies, and
its and their officers, directors, agents, and employees, from and against all
losses, costs, claims, demands, suits, liability and expense with respect to the
Assets which arise out of or relate to Assignee's ownership and/or operation of
such properties.

     Assignee agrees to comply with all laws and with all rules, regulations and
orders of all municipal, state and federal agencies and regulatory bodies in the
conduct of all operations by Assignee in and on the lands covered hereby,
including, but not by way of limitation, the proper plugging of all wells on the
said lands, the proper disposal or treatment of wastes and the transfer or
assumption of applicable permits, bonds, approvals and licenses.

     The provisions of this instrument and the aforementioned Exchange Agreement
shall attach to and run with the leases and lands herein described and shall be
binding upon and shall inure to the benefit of Assignor and Assignee and their
respective (as applicable) heirs, executors, administrators, successors and
assigns.

     
<PAGE>
 
EXHIBIT "A-1"
PAGE 5


      IN WITNESS WHEREOF, the said OXY USA Inc., as Assignor, and Frontier, Inc.
as Assignee, have caused their names to be affixed as of this                  
                                                           ----------------
day of October, 1996, but this Assignment shall be effective as of the Effective
Date herein stated.



                           ASSIGNOR
                           
                           OXY USA INC.


                           By: (AN EXHIBIT - NOT FOR SIGNATURE)            
                               --------------------------------------------    
                                                         , Attorney-in-Fact


                           ASSIGNEE

                           FRONTIER, INC.


                           By: (AN EXHIBIT - NOT FOR SIGNATURE)
                               --------------------------------------------
 
                           Title:
                                 ------------------------------------------ 



                           ASSIGNEE

                           FRONTIER ACQUISITION CORPORATION

 
                           By:   (AN EXHIBIT - NOT FOR SIGNATURE)
                              -----------------------------------------------

- -----------------------------------------------------------------------------
                               ADD ACKNOWLEDMENTS
<PAGE>
 
EXHIBIT "A" -  Attached to and made a part of (Exhibit "A-1") Assignment of Oil
and Gas Leases, and Bill of Sale dated             (*)            , effective
                                       ---------------------------           
September 1, 1996

                              SCHEDULE OF LEASES
                                        
                          WEATHERFORD "A" (7-3591680)
                          ---------------------------
                                   WI: 100%
                                  NRI: 87.5%

   LEASE NUMBER:      63525138/3525138
   DATE OF LEASE:     December 20, 1950
   LESSOR:            Charlotte E. Plaster, now Weatherford
   LESSEE:            Cities Service Oil Company
   RECORDING DATA:    Book 339 Page 10

   DESCRIPTION:       Insofar as lease covers Lot three (3) and Lot four (4)and
                      East Half of the Southwest Quarter (E/2 SW/4), Section 31,
                      Township 4 North, Range 2 West, Garvin Co., Oklahoma

                       HOLLOWAY-WEATHERFORD (7-3540992)
                       --------------------------------
                                   WI: 100%
                                  NRI: 87.5%

   LEASE NUMBER:      63532136/3525138
   DATE OF LEASE:     July 10, 1943
   LESSOR:            T. S. Holloway
   LESS EE:           Harry H. Phillips
   RECORDING DATA:    Book 232 Page 140
 
   DESCRIPTION:       Northwest Quarter of Southeast Quarter, (NW/4 SE/4), North
                      Half of the Southwest Quarter of the Southeast Quarter
                      (N/2 SW/4 SE/4), Southeast Quarter of the Southwest
                      Quarter of the Southeast Quarter (SE/4 SW/4 SE/4), Section
                      31 Township 4 North, Range 2 West, Garvin Co., Oklahoma
                      
   LEASE NUMBER:      63525138/3525138
   DATE OF LEASE:     December 20, 1950
   LESSOR:            Charlotte E. Plaster, now Weatherford
   LESSEE:            Cities Service Oil Company
   RECORDING DATA:    Book 339 Page 10

   DESCRIPTION:       Insofar as lease covers Southwest Quarter of the Southwest
                      Quarter of the Southeast Quarter, (SW/4 SW/4 SE/4) Section
                      31 Township 4 North, Range 2 West, Garvin County, Oklahoma
<PAGE>
 
EXHIBIT "A"
TO EXHIBIT "A-1"
PAGE 2


                             BROWN "K" (7-3508880)
                             ---------------------
                                   WI: 100%
                                  NRI: 87.5%


   LEASE NUMBER:      63523198/3523198
   DATE OF LEASE:     December 27, 1946
   LESSOR:            Lillie C. Brown
   LESSEE:            Carl J. O'Hornet
   RECORDING DATA:    Book 268 Page 348
 
   DESCRIPTION:       Northeast Quarter (NE/4), less right-of-way for railroad;
                      North Half of the Northeast Quarter of the Southeast
                      Quarter (N/2 NE/4 SE/4); Southeast Quarter of the
                      Northeast Quarter of the Southeast Quarter (SE/4 NE/4
                      SE/4) of Section 16 Township 4 North, Range 3 West, Garvin
                      County, Oklahoma, insofar as the above lease covers all
                      rights LESS AND EXCEPT fifty percent (50%) interest from
                      surface down to the base of the Pennsylvania in the South
                      Half of Northeast Quarter (S/2 NE/4), Northwest Quarter of
                      the Northeast Quarter (NW/4 NE/4), and LESS AND EXCEPT
                      sixty-two and a half percent (62.5%) interest in the North
                      Half of the Northeast Quarter of the Southeast Quarter
                      (N/2 NE/4 SE/4) from surface to the Base of the
                      Pennsylvania formation; LESS AND EXCEPT rights from the
                      base of the Pennsylvania formation down to 100' below the
                      stratigraphic equivalent of 10,388' in the North Half of
                      the Northeast Quarter of the Southeast Quarter (N/2 NE/4
                      SE/4) and Southeast Quarter of the Northeast Quarter of
                      the Southeast Quarter (SE/4 NE/4 SE/4), LESS AND EXCEPT
                      rights into the Gibson Sand from 6949' to 7012'.

   LEASE NUMBER:      63531976/3523198
   LEASE DATE:        May 1, 1943
   LESSOR:            Edna Ruth Thompson
   LESSOR:            Harry H. Phillips
   RECORDING DATA:    Book 234 Page 368

   DESCRIPTION:       Southwest Quarter of the Northeast Quarter of the
                      Southeast Quarter (SW/4 NE/4 SW/4) Section 16 Township 4
                      North,
<PAGE>
 
EXHIBIT "A"
TO EXHIBIT "A-1"
PAGE 3
                      Range 3 West, Garvin County, Oklahoma, Insofar as the
                      lease covers a thirty-seven and a half (37.5%) interest
                      from surface to the base of the Pennsylvania formation.

                          SCHEDULE OF SURFACE LEASES
                          --------------------------
 
   LEASE NUMBER:      S3503135
   DATE:              March 15, 1965
   LESSOR:            T. S. Holloway
   LESSEE:            Sinclair Oil & Gas Company
   RECORDING DATA:    Book 667 Page 412
 
   DESCRIPTION:       Northwest Quarter of the Southeast Quarter (NW/4 SE/4)
                      Section 31 Township 4 North, Range 2 West, Garvin Co.,
                      Oklahoma
 
   LEASE NUMBER:      S3500786
   DATE:              October 29, 1963, amended March 19, 1985
   LESSOR:            Samie Leon Weatherford, et ux
   LESSEE:            Cities Service Oil Company
   RECORDING DATA:    Book 636 Page 394

   DESCRIPTION:       Surface of East Half of the Northwest Quarter of the
                      Southeast Quarter (E/2 NW/4 SE/4) and West Half of the
                      Northeast Quarter of the Southeast Quarter of the
                      Southwest Quarter (W/2 NE/4 SE/4 SW/4), Section 31
                      Township 4 North, Range 2 West, Disposal rights into
                      Weatherford "A" #5 well. Pipeline easement across Lots 3
                      and Lots 4 and East half of Southwest Quarter (E/2 SW/4)
                      and Southwest Quarter of the Southwest Quarter of the
                      Southeast Quarter (SW/4 SW/4 SE/4) and Southeast Quarter
                      of the Southeast Quarter of the Northwest Quarter (SE/4
                      SE/4 NW/4) of Section 31 Township 4 North, Range 2 West,
                      Garvin Co., Oklahoma

The above described Oil and Gas Leases are subject to the following:

1.  Contract 35-C-223 between Cities Service Oil Company and Erie P. Halliburton
    Co., dated Mar. 31, 1949 covering oil and gas rights in the S/2 NE/4 Sec 16
    T4N R3W, Garvin Co., Oklahoma.

2.  Contract 35-C-223A between Cities Service Oil Company and Erie P.
    Halliburton
<PAGE>

EXHIBIT "A"
TO EXHIBIT "A-1"
PAGE 4
 
    Company, dated July 12, 1949 covering oil and gas rights in the NE/4 SE/4
    Section 16 T4N R3W, Garvin Co., Oklahoma.

3.  Contract 35-C-1243 between Erie P. Halliburton and Cities Service Oil
    Company, dated November 15, 1949 covering oil and gas rights down to the
    base of the Pennsylvania Formation in NW/4 NE/4 Sec 16 T4N R3W, Garvin Co.,
    Oklahoma

4.  Oklahoma Corporation Commission Order No. 374953, dated July 1, 1993.

5.  Maysville Gasoline Plant Contract dated October 1, 1947

<PAGE>
 
EXHIBIT 10.2
                                SALE AGREEMENT

     THIS AGREEMENT is made and entered into as of September 27, 1996, by and
between FRONTIER ACQUISITION CORPORATION, an Oklahoma corporation (hereinafter
referred to as "Frontier") , with a mailing address at One Allen Center, 500
Dallas Street, Suite 2920, Houston, Texas 77002 and SPECIAL ENERGY CORPORATION,
a Texas Corporation (hereinafter referred to as "Special") with a mailing
address of P.O. Drawer 369 Stillwater, Oklahoma 74076.

                                   RECITALS
                                   --------

     WHEREAS, OXY U.S.A. Inc., a Delaware corporation (hereinafter referred to
as "OXY") is the owner of certain oil and gas real property interests and
related tangible assets located in the County of Garvin, in the State of
Oklahoma, which properties OXY has contracted to convey to Frontier pursuant to
that certain "Exchange Agreement dated as of September 1, 1996, (the "Exchange
Agreement") and;

     WHEREAS, SPECIAL desires to purchase said Garvin County properties from
Frontier subject only to OXY conveying same to Frontier;

     NOW, THEREFORE, in consideration of the mutual benefits to be derived
herefrom, Special and Frontier hereby agree as follows:

                           ARTICLE I  - DEFINITIONS
                           ------------------------

1.1  "Assets" shall refer to and include all of Frontier's right, title and
     -------
interest in and to all depths owned and to those real property interests
described in Exhibit A, attached hereto and made a part hereof for all purposes,
and in and to the personal property as described in Paragraph 1.1(e) which
interests shall include without limitation the following:

     (a)  Oil, gas and other mineral leases ("Leases"), overriding royalty
          interests and other property interests described in Exhibit A, insofar
          and only insofar as such cover and affect the lands described in
          Exhibit A;

     (b)  Any rights and obligations derived from or created by unitization,
          pooling or communitization agreements or units formed under or
          pursuant to orders of any governmental authority;

     (c)  All contracts and contractual rights, obligations and interests
          including but not limited to unit agreements, farmout or farmin
          agreements, operating or joint operating agreements, production sales
          contracts [but, as to the interests described on Exhibit A, excluding
          that certain agreement for the Purchase and Sale of Crude Oil executed
          the 31st day of August, 1983, by and between Occidental Petroleum
          Corporation, et al and CITGO Petroleum Corporation, et
<PAGE>
 
SALE AGREEMENT
PAGE 2
          al, (the "CITGO Contract")], gas purchase contracts, processing
          contracts, gas balancing agreements, only insofar as such are
          assignable and relate to the interests described in Exhibit A. Such
          contracts shall hereinafter be referred to as "Existing Contracts";

     (d)  Surface fee interests, surface use agreements, easements, permits and
          rights-of-way and similar rights and interests applicable to or used
          or useful in connection with any or all of the interests described in
          Exhibit A;

      (e) All wells, equipment, facilities and personal property (excluding
          vehicles) located on the lands described in Exhibit A, and used solely
          and directly in connection with the production, operation, treatment
          or transportation of oil and/or gas from those certain depths and
          lands described in Exhibit A, including, but not limited to, pumping
          equipment, storage facilities, pipelines, treatment equipment, meter
          stations, salt water disposal wells, separators, compressors, tanks,
          tank batteries and other fixtures;

     (f)  The oil, gas of any kind and nature, other hydrocarbons and other
          minerals in, on and produced from and after the Effective Date hereof;
          and

     (g)  Copies of original records, files, reports and other written material
          relating directly to the interests described in Exhibit A including,
          but not limited to, lease files, property records, contract files,
          operation files, maintenance files, development geological records,
          contractor files, financial records, NGPA filings and records,
          landowner files, reports to regulatory agencies.

     (h)  Notwithstanding the foregoing, the definition of Assets shall not
          include any record, file, written document, or any other document,
          information or tangible thing that is identified as being subject to:
          (1) any confidentiality agreement (unless transfer is otherwise
          permitted thereunder), (2) any agreement to inhibit or restrict the
          transfer of such document, information or tangible thing, or (3) any
          claim of attorney work product or attorney client privilege.

1.2    "Assignee" refers to the party hereto which will own the Assets after the
       ----------
Effective Date: namely, Special is the Assignee with regard to the Assets
described on Exhibit A.

1.3    "Assignor" refers to the party assigning its rights in the Assets as of
       ----------
the Effective Date: namely Frontier is the Assignor with regard to the Assets
described on Exhibit A.

1.4    "Effective Date."  Only in the event Closing occurs, the effective date
       -----------------
of the exchange contemplated herein shall be September 1, 1996,  7:00 a.m.
Central Daylight Time where the Assets are located .
<PAGE>
 
SALE AGREEMENT
PAGE 3

1.5    "Title Defects" shall mean any material encumbrance, encroachment,
       ---------------
irregularity, defect in, or objection to Assignor's title to the Assets, which,
based upon petroleum industry standards for the area in which the affected
property is located, alone or in combination with other defects, would
unreasonably interfere with Assignee's use and enjoyment of the Assets as
currently used. "Title Defect" shall also mean the inability of Assignor to
assign to Assignee at least the royalty interest in the Assets and/or at least
the net revenue interest in the Assets and not greater than the cost bearing
working interest in the Assets than those undivided percentage interests set
forth in Exhibit A.

                          ARTICLE II - SALE OF ASSETS
                          ---------------------------

2.1    ASSIGNMENT BY FRONTIER.   Subject to the other provisions of this
       -----------------------                                          
Agreement, Frontier shall assign to Special all of Frontier's right, title and
interest in and to the Assets, as defined above and as described in Exhibit "A",
in the form of assignment attached hereto as Exhibit "A-1".

                          ARTICLE III - CONSIDERATION
                          ---------------------------

     The consideration for this Agreement is the mutual exchanges, payments and
assignments between the Parties described herein, including as consideration for
the Assets described in Exhibit A, Special agrees to pay at Closing to Frontier
Seven Hundred Ten  Thousand Dollars ($710,000).  This additional consideration
shall be paid at Closing to Frontier, at Frontier's direction, by cashiers
check.

As further Consideration, Assignee hereby agrees, as of the Effective Date, to
assume, perform and comply with all of the provisions and obligations (expressed
or implied), that are attributable to the Assets, including without limitation
the following:

     (a)  All the terms and conditions of the Leases and of the contracts,
          agreements and instruments which relate to the Assets, including but
          not limited to, those described in Exhibit A.

     (b)  Compliance with any and all laws, ordinances, rules and regulations
          affecting the Assets, and the operation thereof, including but not
          limited to (a) those related to the proper plugging and abandonment of
          all wells, whether currently producing or non-producing, which are
          part of the Assets, or which are thereafter drilled on the Assets, (b)
          those related to removal of all equipment and facilities and to
          restoration of the surface of the lands included in the Assets, and
          (c) those related to inactive or unplugged wells, bonding and
          permitting, and to the use of explosives in shooting or pulling of
          casing and tubing.
<PAGE>
 
SALE AGREEMENT
PAGE 4

             ARTICLE IV - REPRESENTATIONS AND WARRANTIES BY PARTIES
             ------------------------------------------------------

Frontier, as Assignor, hereby makes the following representations and warranties
as of the Closing Date to the Assignee:

4.1    AUTHORIZATION.
       ------------- 

     (a)  Organization and Standing.  Assignor is a corporation duly organized,
          -------------------------                                            
          validly existing and in good standing under the laws of its state of
          incorporation and is duly qualified to acquire and operate the Assets.

     (b)  Corporate Power.  Assignor has the corporate power to enter into and
          ---------------                                                     
          perform this Agreement and to consummate the transactions contemplated
          hereby. The execution, delivery and performance of this Agreement by
          Assignor, and the transactions contemplated hereby, do not violate (i)
          any provision of the articles of incorporation or bylaws of Assignor,
          or (ii) any judgment, order, ruling or decree applicable to Assignor
          as a party in interest.

     (c)  Execution and Delivery. The execution, delivery and performance of
          ----------------------
          this Agreement and the consummation of the transactions contemplated
          hereby have been duly and validly authorized by all requisite
          corporation action on the part of Assignor and this Agreement has been
          duly executed and delivered on behalf of Assignor.

     (d)  Validity of Agreement.  This Agreement constitutes a legal, valid and
          ---------------------                                                
          binding obligation of Assignor, enforceable against Assignor in
          accordance with its terms, except that such enforcement may be subject
          to (i) bankruptcy, insolvency, reorganization or other similar laws
          now or hereafter in effect affecting the enforcement of creditors;
          rights generally, and (ii) general principles of equity (regardless of
          whether enforcement is considered in a proceeding in equity or at
          law).

4.2    TITLE.  With regard to the Assets it conveys, except as to otherwise
       -----                                                               
provided herein, ASSIGNOR DOES NOT WARRANT OR REPRESENT, EITHER EXPRESSLY OR BY
IMPLICATION, TITLE TO PROPERTY (REAL OR PERSONAL), THE CONDITION OF ANY WELLS OR
EQUIPMENT OR THE QUANTITY, QUALITY OR CONDITION OF ANY MATERIAL OR EQUIPMENT OR
ITS FITNESS FOR USE OR THE SUITABILITY FOR USE OF SAME IN WHOLE OR IN PART.
ASSIGNOR DISCLAIMS ANY IMPLIED WARRANTY OF MERCHANTABILITY OF ANY PERSONAL
PROPERTY OR OF THE FITNESS OF ANY PERSONAL PROPERTY FOR ANY PURPOSE, AND
ASSIGNEE AGREES THAT ANY PERSONAL PROPERTY IS SOLD "AS IS" AND "WHERE IS".
ASSIGNOR DOES NOT MAKE ANY REPRESENTATION OR WARRANTY, EXPRESS OR IMPLIED, AT
COMMON LAW, BY STATUTE OR OTHERWISE RELATING TO THE ACCURACY OR COMPLETENESS OF
ANY INFORMATION, DATA OR OTHER MATERIALS (WRITTEN OR ORAL) HERETOFORE OR
HEREAFTER  FURNISHED TO ASSIGNEE BY OR ON BEHALF OF ASSIGNOR.
<PAGE>
 
SALE AGREEMENT
PAGE 5

4.3    REPRESENTATIONS.
       --------------- 

     (a)  Mortgages and Other Instruments.  To the best of Assignor's knowledge,
          -------------------------------                                       
          neither the performance of this Agreement, nor the consummation of the
          transactions contemplated by this Agreement, will cause a breach of
          any of the terms and conditions of any agreement or other instrument
          to which Assignor is a party or by which it is bound or result in the
          creation or imposition of any lien upon any of the Assets, or the
          production of oil, gas or other minerals from the Assets.

     (b)  Brokers.  Assignor has not incurred any liability, contingent or
          -------                                                         
          otherwise, for brokers' or finders' fees relating to the transactions
          contemplated by the Agreement for which Assignee shall have any
          responsibility whatsoever.

            ARTICLE V - REPRESENTATIONS AND WARRANTIES BY ASSIGNEE
            ------------------------------------------------------

     Special in its capacity as Assignee hereunder and with respect to the
Assets for which it is Assignee, represents and warrants to Frontier:

     (a)  Organization and Standing.  Assignee is a corporation duly organized,
          -------------------------                                            
          validly existing and in good standing under the laws of the state of
          its incorporation and is duly qualified to acquire and operate the
          Assets in the state in which the Assets are located.

     (b)  Corporate Power.  Assignee has the corporate power to enter into and
          ---------------                                                     
          perform this Agreement and the transactions contemplated hereby.
          Subject to rights to consent by governmental entities and required
          notices to and filings with governmental entities where the same are
          customarily obtained or made subsequent to the assignment of oil and
          gas interests and leases, the execution, delivery and performance of
          this Agreement by Assignee and the transactions contemplated hereby
          will not violate (i) any provision of the articles of incorporation or
          bylaws of Assignee, or (ii) any judgement, order, ruling or decree
          applicable to Assignee as a party in interest.

     (c)  Execution and Delivery. The execution, delivery and performance of
          ----------------------
          this Agreement and the transactions contemplated hereby have been duly
          and validly authorized by all requisite corporate action on the part
          of Assignee. This Agreement has been duly executed and delivered. This
          Agreement does, and such documents and instruments shall, constitute
          legal, valid and binding obligations of Assignee enforceable in
          accordance with their terms.
<PAGE>
 
SALE AGREEMENT
PAGE 6


     (d)  Validity of Agreement.  This Agreement does, and such documents and
          ---------------------                                              
          instruments shall, constitute a legal, valid and binding obligation of
          Assignee, enforceable against Assignee in accordance with its terms,
          except that such enforcement may be subject to (i) bankruptcy,
          insolvency, reorganization or other similar laws now or hereafter in
          effect affecting the enforcement of creditors' rights generally, and
          (ii) general principles of equity (regardless of whether enforcement
          is considered in a proceeding in equity or at law).

     (e)  Licenses and Permits. At or prior to Closing, Assignee shall obtain or
          --------------------
          satisfy Assignor that it will obtain all licenses, bonds, permits and
          other approvals which to the best of Assignee's knowledge are required
          to be obtained by it to succeed Assignor as owner of its Assets.

     (f)  Assumption of Obligations.  Assignee shall assume, and agrees and
          -------------------------                                        
          covenants to perform, all the express and implied covenants, duties
          and obligations of Assignor relating to its Assets which shall accrue
          under applicable leases, contracts or agreements or are required by
          applicable laws and regulations.

     (g)  Further Distribution.  Assignee is acquiring the Assets for its own
          --------------------                                               
          account and not with view to, or for offer or resale in connection
          with, a distribution or transfer thereof within the meaning of the
          Securities Act of 1933 and the rules and regulations pertaining to it
          or in violation of any applicable federal and state securities laws.

     (h)  Brokers.  Assignee has not incurred any liability, contingent or
          -------                                                         
          otherwise, for brokers' or finders' fees relating to the transactions
          contemplated by this Agreement for which Assignor shall have any
          responsibility whatsoever.

               ARTICLE VI - CONDUCT OF BUSINESS PRIOR TO CLOSING
               -------------------------------------------------

6.1    OPERATION OF ASSETS. In that Assignor will only acquire title to the
       -------------------                                                 
assets concurrent with this sale, Assignor cannot and does not make any
representation as to operation of the assets.  Assignor shall, to the extent it
has certain control rights pursuant to the Exchange Agreement as regards to the
assets as to access to information and access to the assets provide same to
Special.

6.2    INDEPENDENT EVALUATION AND TITLE REVIEW.  As soon as possible after
       ---------------------------------------                            
execution of this Agreement, Frontier shall, to the extent it is provided for in
the Exchange Agreement authorize Special to have access during normal business
hours to all records and documents in OXY's possession affecting title to the
Assets.  It is Special's responsibility to satisfy itself as to the condition of
the Assets and title thereto prior to Closing of the subject transaction.
ASSIGNEE ACKNOWLEDGES THAT ASSIGNOR HAS MADE NO REPRESENTATIONS, VERBAL OR
OTHERWISE, OR WARRANTIES AS TO THE ACCURACY OR COMPLETENESS 
<PAGE>
 
SALE AGREEMENT
PAGE 7


OF SUCH INFORMATION, OR AS TO ASSIGNOR'S TITLE TO THE ASSETS, AND, IN ENTERING
INTO AND PERFORMING THIS AGREEMENT, ASSIGNEE HAS RELIED AND WILL RELY SOLELY
UPON ITS INDEPENDENT INVESTIGATION OF, AND JUDGEMENT WITH RESPECT TO, THE
ASSETS, THEIR VALUE AND ASSIGNOR'S TITLE THERETO.

6.3    CASUALTY LOSSES.  If prior to the Closing Date any facility or equipment
       ---------------                                                         
included within the Assets to be transferred by Assignor is damaged or destroyed
by fire, flood, storm or other casualty (hereinafter called "Casualty Loss"),
Assignor shall as soon as Assignor is aware,  notify Assignee.  Assignee shall
have the option to proceed with the exchange under the terms and conditions of
this Agreement, renegotiate the exchange, or to terminate the exchange without
any further liability to either party.  Should Assignee elect to proceed with
the exchange, Assignee shall receive any insurance proceeds payable to Assignor
with respect to such Casualty Loss.

6.4    HART-SCOTT-RODINO ACT.  Each party shall make all filings required of it
       ---------------------                                                   
under the Hart-Scott-Rodino Act of 1976, and rules and regulations promulgated
pursuant thereto (the "HSR Act"), by virtue of the exchange contemplated
hereunder.

                  ARTICLE VII - ADJUSTMENT OF EXCHANGE VALUES
                  -------------------------------------------

     On or before ten (10) days prior to Closing, the party to whom an Asset is
to be assigned shall deliver to the party transferring such Asset written notice
of any matters which either constitute a Title Defect or cause a breach of the
representations and warranties as set forth in Article IV herein made with
respect to that Asset. The party transferring such Asset, at its sole cost and
expense, may attempt to cure such matters. In the event that party is unable or
chooses not to cure such matter, or in the event of a Casualty Loss as set forth
in Article VI herein, the party receiving the Asset may terminate this Agreement
and all rights and obligations associated therewith, or it may choose to proceed
with the exchange on the terms and conditions set forth in this Agreement, or
renegotiate the exchange with the other party. In no event shall either party
ever be required to contribute cash to make up losses in value occasioned by
Title Defect or Casualty Loss.

The parties agree that this Article VII shall provide the sole remedy for
addressing any Title Defect or any breach of the representations and warranties
contained in Article IV.  At Closing hereunder, except as otherwise agreed to in
writing, the parties shall be conclusively deemed to have waived any and all
Title Defects or breaches of the representations and warranties contained in
Article IV hereof.

       ARTICLE VIII - PROCEEDS, ROYALTY OBLIGATIONS, EXPENSES AND TAXES
       ----------------------------------------------------------------

8.1    ACCOUNTING FOR PRODUCTION AND PROCEEDS OF PRODUCTION.  The right to
       ----------------------------------------------------               
production from or attributable to the Assets shall pass from Assignor to
Assignee as of the Effective Date.  OXY shall retain ownership and be entitled
to all proceeds from the sale of any 
<PAGE>
 
SALE AGREEMENT
PAGE 8

oil and plant products in tanks or storage facilities above the pipeline
connections, attributable to the Assets prior to the Effective Date. If Assignor
should at any time subsequent to the Closing Date receive from any purchasers of
production any proceeds attributable to any sale of production from the Assets
occurring after the Effective Date, Assignor shall promptly remit all such
amounts to Assignee. Similarly, if Assignee should at any time after the Closing
Date receive any proceeds attributable to any such sale occurring prior to the
Effective Date, Assignee shall promptly remit the same to Assignor.

8.2    ROYALTY OBLIGATIONS:  EXPENSES.  OXY shall be responsible for the payment
       ------------------------------                                           
of all royalty obligations, operating expenses and capital expenses attributable
to the Assets prior to the Effective Date, however, Assignor shall not be
responsible for those royalty obligation amounts attributable to the Assets
prior to the Effective Date and which were held in suspense by OXY and
transferred to Assignee at Closing or through the post closing adjustment
provided for in Article XI.  Assignee shall be responsible for the payment of
all royalty obligations, operating expenses and capital expenses attributable to
the Assets after the Effective Date.  Assignee shall also assume full
responsibility for the payment of all funds arising out of production from the
Assets which have been deposited in accordance with various state escrow
statutes.  At Closing, Assignor shall furnish, to the extent it has same, a
listing of all accounts and funds so held or deposited.  Assignee agrees to and
shall indemnify, defend and hold Assignor harmless for all actions arising out
of or in connection with the deposit or disbursement of said funds.  A party
paying any such royalties or expenses which are the responsibility of the other
party shall be entitled to prompt reimbursement upon evidence of such payment.

8.3    TAXES.  All taxes (other than income taxes or sales taxes) relating to
       -----                                                                 
production of oil, gas and condensate attributable to the Assets prior to the
Effective Date, regardless of the basis therefore, shall be the obligation of
and paid by OXY, and all taxes relating to such production on or after the
Effective Date shall be the obligation of and paid by Assignee.

8.4    SALES OR TRANSFER TAXES.  The consideration provided for hereunder is net
       -----------------------                                                  
of any applicable sales taxes or other transfer taxes in connection with the
exchange of the Assets.  Assignee shall be liable for any sales tax or other
transfer tax, as well as any applicable conveyance, transfer and recording fee,
and real estate transfer stamps or taxes imposed on the transfer of the Assets
pursuant to this Agreement.  Assignee shall indemnify and hold Assignor harmless
with respect to the payment of any such taxes and fees including any interest or
penalties assessed thereon.

8.5    COOPERATION.  Each party shall provide reasonable access during normal
       -----------                                                           
business hours to all relevant documents, data and other information which may
be required by the other party for the purpose of preparing tax returns and
responding to any audit by any governmental entity.  Each party shall cooperate
with all reasonable requests of the other party made in connection with
contesting the imposition of taxes.  Notwithstanding anything to the contrary in
this Agreement, neither party shall be required at any time to disclose to the
other party any tax returns or other confidential tax information.
<PAGE>
 
SALE AGREEMENT
PAGE 9

8.6    JOINT BILLING AUDITS:  CREDITS.  To the extent that the interest to be
       ------------------------------                                        
conveyed pursuant hereto is a cost bearing working interest, Assignor shall be
responsible for and entitled to the settlement of all joint billing audits which
relate to accounting periods prior to Effective Date. Assignee shall be
responsible for and entitled to the settlement of all joint billing audits which
relate to accounting periods after the Effective Date. Any amounts and credits
received by Assignee after the Effective Date attributable to expenses paid
prior to the Effective Date shall be reimbursed to Assignor by Assignee.

                             ARTICLE IX - CLOSING
                             --------------------

9.1    CONDITIONS TO CLOSING.
       --------------------- 

     (a)  Conditions to Obligations of Assignee. The obligations of Assignee to
          -------------------------------------
          be performed at the Closing are subject to the satisfaction of the
          following conditions, any one or more of which may be waived in whole
          or in part by Assignee:

          (i)   Representations and Warranties. The representations of Assignor
                ------------------------------
                set forth in this Agreement shall be true and correct in all
                material respects as of the Closing Date (except as may be
                specifically contemplated hereby).

          (ii)  Performance of Obligations of Assignor.  Assignor shall have
                --------------------------------------                      
                performed in all material respects all conditions required to be
                performed by it under this Agreement prior to or on the Closing
                Date.

          (iii) Intentionally left blank.

          (iv)  Litigation. No suit or other proceeding shall be pending before
                ----------
                any court or governmental agency seeking to restrain or prohibit
                the exchange contemplated by this Agreement.

          (v)   No Violations. The Closing shall not violate any order or decree
                -------------
                of any court or governmental body having competent jurisdiction.

          (vi)  Liens. The Assets shall be delivered free and clear of any
                -----
                liens, mortgages, security interests, production payments, net
                profits interest or other similar encumbrances by, through and
                under Assignor, and in the event the Assets have an existing
                lien, it will be released prior to Closing.

          (vii) Prior Contractual Requirement.  Frontier shall have concurrent
                -----------------------------                                 
                herewith or prior to closing of this agreement, closed its
                acquisition of the assets from OXY pursuant to the Exchange
                Agreement.
<PAGE>
 
SALE AGREEMENT
PAGE 10

     (b)  Conditions to Obligations of Assignor. The obligations of Assignor to
          -------------------------------------
          be performed at the Closing are subject to the satisfaction of the
          following conditions, any one or more of which may be waived in whole
          or in part by Assignor:


          (i)   Representations and Warranties. The representations of Assignee
                ------------------------------
                set forth in this Agreement shall be true and correct in all
                material respects as of the Closing Date .

          (ii)  Performance of Obligations of Assignee.  Assignee shall have
                --------------------------------------                      
                performed in all material respects all conditions required to be
                performed by it under this Agreement prior to or on the Closing
                Date.

          (iii) Litigation.  No suit or other proceeding shall be pending before
                ----------                                                      
                any court or governmental agency seeking to restrain or prohibit
                the exchange contemplated by this Agreement. Upon receipt,
                Assignee shall also execute and acknowledge the conveyance
                documents.

          (iv)  No Violations. The Closing shall not violate any order or decree
                -------------
                of any court or governmental body having competent jurisdiction.

9.2    DATE AND PLACE OF CLOSING.  The Closing of the exchange of the Assets
       -------------------------                                            
shall take place at the offices of OXY at such time and date as may be agreed
upon by Frontier, OXY  and Special (the "Closing Date"), but not later than
October 15, 1996, unless otherwise mutually agreed to in writing by the parties.

9.3    CLOSING OBLIGATIONS.  At the Closing the following events shall occur,
       -------------------                                                   
each being a condition precedent to the others and each being deemed to have
occurred simultaneously with the others:

     (a)  Assignor shall execute, acknowledge and deliver to Assignee conveyance
          documents substantially in the form set forth in Exhibit A to this
          Agreement as to all Assets and such other instruments of transfer and
          assignment necessary to convey to Assignee or its subsidiary the
          Assets in the manner contemplated by this Agreement. Upon receipt,
          Assignee shall also execute and acknowledge the conveyance documents
          and shall file such documents for recording in a timely fashion with
          the proper authorities in the appropriate counties. Thereafter,
          Assignee shall provide Assignor with all recording information.

     (b)  Assignor shall deliver to Assignee exclusive possession of the Assets,
          and Assignee shall take possession of the Assets, effective as of the
          Effective Date.
<PAGE>
 
SALE AGREEMENT
PAGE 11

     (c)  Assignor and Assignee shall execute, acknowledge, and deliver transfer
          orders or letters in lieu thereof directing all purchasers of
          production to make payments of proceeds attributable to production
          from the Assets to Assignee.

     (d)  Assignor and Assignee shall execute, acknowledge and deliver such
          other instruments and take such other action as may be necessary to
          carry out their respective obligations under this Agreement,
          including, but not limited to, assignment of Operating Rights (if
          applicable) on forms acceptable to the
          appropriate governmental entity.

     (e)  Special shall pay to Frontier (as directed) the consideration provided
          for in Article III.

     (f)  Frontier shall have, concurrent herewith or prior closing, closed the
          Exchange Agreement with OXY thereby acquiring its interest in the
          Assets.

                     ARTICLE X - TERMINATION OF AGREEMENT
                     ------------------------------------

     (a)  In addition to termination pursuant to Section 6.3 or Article VII,
          this Agreement may be terminated at any time prior to the Closing Date
          by:


          (i)   Either party hereto, if consummation of the transactions
                contemplated hereby would violate any non-appealable final order
                of any court or governmental body having competent jurisdiction;

          (ii)  Either party hereto, if prior to Closing, any legislation which
                would have the effect of prohibiting or making unlawful the
                acquisition or ownership of the Assets by Assignee or the
                conveyance or trade of the Assets by Assignor has been enacted
                into law.

     (b)  This Agreement shall terminate in the event either party fails to
          fulfill the conditions of Article IX, which give rise to the other
          parties' obligation to close, unless such other party waives the
          unfulfilled conditions.

     (c)  In the event of the termination of this Agreement pursuant to the
          provisions of this paragraph, this Agreement shall become void and
          have no effect, without any liability on the part of either party or
          any of its directors, officers, partners, employees or stockholders.

                    ARTICLE XI - OBLIGATIONS AFTER CLOSING
                    --------------------------------------

11.1   POST-CLOSING ADJUSTMENTS.  Within one hundred twenty (120) days after
       ------------------------                                             
Closing, a final settlement statement will be prepared by each party of the
Assets assigned by that 
<PAGE>
 
SALE AGREEMENT
PAGE 12

party and submitted to the other, showing income and expenses for the Assets
between the Effective Date and Closing Date and other charges and credits
provided in this Agreement.

     (a)  Assignor shall be credited with:

          (i)   The value of all merchantable oil and plant products above the
                pipeline connections in tanks and storage facilities at the
                Effective Date that is credited to Assignor's net revenue or
                royalty interest in the Assets, such value to be the actual
                price received by Assignee as of the Effective Date, less any
                taxes withheld properly by the purchaser of such.

          (ii)  The amount of all costs and expenses, including, without
                limitation, rentals and other charges, ad valorem and other
                taxes based upon or measured by the ownership of property or the
                production of hydrocarbons or the receipt of proceeds therefrom,
                expenses paid under applicable operating agreements and, in the
                absence of an operating agreement, expenses of the sort
                customarily billed under such agreements, not including income
                taxes, paid by or on behalf of Assignor, in connection with the
                operation of the Assets for work performed during the period
                after the Effective Date.

          (iii) An amount equal to all prepaid expenses attributable to the
                Assets that are paid by or on behalf of Assignor prior to or
                after the Closing Date and that are, in accordance with
                generally accepted accounting principles, attributable to the
                period after the Effective Date, including without limitation,
                prepaid ad valorem, property, production, severance, and similar
                taxes (but not including income taxes) based upon or measured by
                the ownership of property or the production of hydrocarbons on
                the receipt of proceeds therefrom. Any refund of ad valorem tax
                attributable to the period before the Effective Date received by
                Assignee shall be credited to Assignor.

     (b)  Assignee shall be credited with:

          (i)   Proceeds net of royalties received by Assignor that are, in
                accordance with generally accepted accounting principles,
                attributable to the Assets for the period of time after the
                Effective Date.

          (ii)  The amount of all costs and expenses, including, without
                limitation, rentals and other charges, ad valorem, property,
                production, excise, severance, windfall profit, and other taxes
                based upon or measured by the ownership of property or the
                production of hydrocarbons or the receipt of proceeds therefrom,
                expenses paid under applicable operating agreements and, in the
                absence of an operating agreement, expenses of the sort
                customarily 
<PAGE>
 
SALE AGREEMENT
PAGE 13

                billed under such agreements, not including income taxes, paid
                by or on behalf of Assignee, in connection with the operation of
                the Assets for work performed during the period prior to the
                Effective Date.

          (iii) The amount attributable to royalty obligations held in suspense
                by Assignor and attributable to the Assets prior to the
                Effective Date.

     (c)  In addition to the matters mentioned above, the final settlement
          statement shall include any other debits and credits, either cash or
          accrued, but excluding income and franchise taxes, which under
          generally accepted accounting principles would reflect transfer of
          ownership of the Assets on the Effective Date.

     (d)  The net amount to be paid by the owing party shall be paid within
          thirty (30) days after receipt of the final settlement statement.
          Assignee shall have the right for a period of one hundred twenty (120)
          days from the date of the final settlement statement in which to audit
          the matters covered thereby.

     (e)  In the event Assignee and Assignor are unable to mutually agree upon
          the amount of the settlement statement, an audit shall be conducted by
          an accounting firm on which the parties mutually agree. Assignee and
          Assignor agree to be bound by the findings of such audit, insofar as
          the final settlement statement amount is concerned, and each shall
          bear one half of all expenses associated with such audit.

11.2   FURTHER ASSURANCES.  After Closing, Assignor agrees to execute and
       ------------------                                                
deliver to Assignee all such instruments, notices, division or transfer orders,
and other documents, and to do all such other acts not inconsistent with this
Agreement as it has the legal right to convey and which may reasonably be
necessary or advisable to carry out its obligations under this Agreement or to
more fully assure Assignee, its successors and assigns, of the respective
rights, titles, interests and estates herein provided to be assigned and
conveyed by Assignor to Assignee at Closing.

11.3   EXISTING OBLIGATIONS.
       -------------------- 

     (a)  Existing Contracts. The Assets will be conveyed subject to any and all
          ------------------
          Existing Contracts, as well as any and all other agreements pertaining
          thereto which are of record or of which Assignee has actual notice. To
          the extent of the interest acquired by Assignee hereunder, Assignee
          agrees to and shall assume and be responsible for all obligations of
          Assignor under such Existing Contracts and other agreements as of the
          Effective Date. Should any such agreement provide for a preferential
          right to purchase or require prior consent to assign, then the
          obligation of Assignee to purchase the property affected thereby shall
          be subject to Assignor obtaining such waiver or consent prior to the
          Closing Date.
<PAGE>
 
SALE AGREEMENT
PAGE 14

     (b)  Special and Frontier agree that this exchange of Assets is subject to
          and OXY does hereby reserve the Citgo Contract, and the option, hereby
          exercised and exercisable at any time and from time to time after the
          Effective Date, of purchasing or marketing for the benefit of Special
          all of the share of oil produced from or allocated to the Assets shown
          on Exhibit "A" applicable to the interest therein acquired by Special
          hereunder at the price provided in the Citgo Contract.

                         ARTICLE XII - INDEMNIFICATION
                         -----------------------------

12.1   Assignee shall, (i) at the Effective Time assume, and be responsible for
and comply with all duties and obligations of Assignor, express or implied, with
respect to the interests, including, without limitation, those arising under or
by virtue of any lease, contract, agreement, document, permit, applicable
statute or rule, regulation or order of any governmental authority (specifically
including, without limitation, any governmental request or requirement to plug,
re-plug and/or abandon any well of whatsoever type, status or classification, or
take any clean-up or other action with respect to the property or premises) and
(ii) defend, indemnify and hold Assignor harmless from any and all claims in
connection therewith, except any such claims arising out of, resulting from, or
relating to the ownership or operation of the interests by Assignor prior to the
Effective Time.

12.2   Assignee shall defend, indemnify and hold Assignor harmless from any and
all claims in favor of any person, corporation, partnership, governmental or
regulatory agency, or other legal entity for personal injury; death or damage to
property or to the environment, or for any other relief, arising directly or
indirectly from, or incident to, the use, occupation, operation, maintenance or
abandonment of any of the interests, or condition of the property or premises,
whether latent or patent, resulting from or arising out of the conditions,
actions or inactions from and after the Effective Time.

12.3   OXY shall (i) be responsible for any and all claims arising out of the
production or sale of hydrocarbons from the interests -- or the proper
accounting or payment to parties for their interests therein -- insofar as such
claims relate to periods of time prior to the Effective Time and (ii) defend,
indemnify and hold Assignee harmless from any and all such claims.  Assignee
shall be responsible for all of said types of claims insofar as they relate to
periods of time from and after the Effective Time, and shall defend, indemnify
and hold Assignor harmless therefrom.

12.4 Intentionally left blank.

12.5   Notwithstanding any other provision contained herein to the contrary,
Assignee acknowledges that the Assets have been utilized for the purpose of
exploration, production and development of oil and gas, and that Assignee has
been informed and is aware that oil and gas producing formations can contain
naturally occurring radioactive material (NORM) and that some oil field
production equipment and/or facilities may contain asbestos and/or NORM.
Assignee has inspected the property and premises and satisfied itself as to
their physical and environmental condition, both surface and subsurface.
<PAGE>
 
SALE AGREEMENT
PAGE 15

12.6   In addition to provisions 12.1 and 12.2 above, to the extent that the
interest  received is, or may become, a cost bearing working interest Assignee
agrees to defend, indemnify and hold harmless Assignor and its affiliated
companies, and its and their officers, directors, agents, and employees, from
and against all losses, costs, claims, demands, suits, liability and expense
with respect to the Assets which arise out of or relate to Assignee's ownership
and/or operation of such Assets.


                          ARTICLE XIII - MISCELLANEOUS
                          ----------------------------


13.1   INTENT.  It is the intent of Frontier to assign and of Special to receive
       ------                                                                   
all of the interest Frontier receives from OXY in those Assets described in
Exhibit "A".   In the event that any interests owned by Assignor in such
properties are omitted or incorrectly described, the parties agree to execute
the documents necessary to effect the intent stated herein.

13.2   IMBALANCES.  Assignee has made an independent investigation into the gas
       ----------                                                              
imbalances and has taken such imbalances into consideration in this Agreement.
Assignee shall assume all of Assignor's rights, duties, benefits, obligations or
liability for any production imbalances relating to the Assets transferred as of
the Effective Date.  In the event that Assignor's gas production, if any, from
any of the Assets is out of balance, Assignee shall acquire the Assets subject
to such overproduction or underproduction and no adjustment shall be made.  In
the case of Assets in which Assignor is underproduced, Assignee shall acquire
all of Assignor's rights to recoup such underproduction, whether pursuant to a
gas balancing agreement or otherwise, subject to applicable royalty and tax
burdens.  In the case of Assets in which Assignor is overproduced, Assignee
shall acquire the Assets subject to, and Assignee shall indemnify Assignor with
regard to, the obligation to balance, either in kind or in cash, the gas
production with the underproduced parties in the Assets.   In the event Assignor
has received payment for gas not actually taken under a gas sales contract's
"take-or-pay" or similar provision, which will obligate Assignee to deliver gas
at some future time from the Assets without receiving full payment therefor or
will require payment of such "take-or-pay" payment, an adjustment will be made
between the parties by the amount of such "take-or-pay" payment.

13.3   INTEGRATION:  AMENDMENT AND MODIFICATION.  Except as expressly set forth
       ----------------------------------------                                
herein, neither of the parties makes to the other any representation or
warranty, whether expressed or implied, of any kind whatsoever.  This Agreement
may not be modified, supplemented or changed in any respect except by a writing
duly executed by both parties hereto.

13.4   DESCRIPTION HEADINGS.  The headings of the paragraphs and subparagraphs
       --------------------                                                   
of this Agreement are inserted for convenience only and shall not constitute a
part hereof.
<PAGE>
 
SALE AGREEMENT
PAGE 16

13.5   GOVERNING LAW.  THE PARTIES HEREBY AGREE THAT THIS AGREEMENT SHALL BE
       -------------                                                        
GOVERNED BY AND CONSTRUED IN ACCORDANCE WITH THE LAWS OF THE STATE OF OKLAHOMA.

13.6   BINDING EFFECT:  ASSIGNMENT.  This Agreement shall be binding upon and
       ---------------------------                                           
shall inure to the benefit of and be enforceable by each of the parties, and
their successors and permitted assigns.  This Agreement shall not be assigned
prior to the Closing Date by either party hereto without the consent of the
other, except that either party may assign its rights hereunder to any
subsidiary or affiliate.

13.7   REMOVAL OF SIGNS.  In the case of Assignor-operated properties, Assignee
       ----------------                                                        
shall remove OXY's name from the property on or as soon as possible after the
actual closing date. Within ten (10) days of the Closing Date, Assignee shall
post its own signs in compliance with applicable state regulations. In the event
Assignee fails to do so, Assignor's representatives shall have full access to
the property for such purpose.

13.8   NOTICES.  All notices, disclosures or other information which are
       -------                                                          
required or permitted hereunder shall be in writing and shall be delivered as
follows:

  FRONTIER'S MAILING ADDRESS:              SPECIAL'S MAILING ADDRESS:
  ---------------------------              --------------------------

  Frontier Acquisition Corporation         Special Energy Corporation
  One Allen Center                         P. O. Drawer 369
  500 Dallas Street, Suite 2920            Stillwater, Oklahoma, 74076
  Houston, Texas 77002

13.9   COUNTERPARTS.  This Agreement may be executed in any number of
       ------------                                                  
counterparts and each such counterpart hereof shall be deemed to be an original,
and all of which together shall constitute one and the same instrument.  This
Agreement shall not be binding on any named party until it is signed by or
validly on behalf of all named parties and, where applicable, their spouses.

13.10  TAXES.
       ----- 

     (a)  Neither party makes any warranty of any particular tax treatment which
          might be afforded the other party under this Agreement.

     (b), (c), (d), (e) "Intentionally left blank".


13.11  SEVERABILITY.  If any provision of this Agreement is held invalid, the
       ------------                                                          
remainder of the Agreement shall not be affected thereby unless the effect
thereof would be to materially alter the burdens or benefits intended by the
parties by the express language of this Agreement.
<PAGE>
 
SALE AGREEMENT
PAGE 17

13.12  NO PARTNERSHIP CREATED.  The parties do not intend that this Agreement
       ----------------------                                                
create (and it shall not be construed to create) a joint venture, partnership or
any type of association.  No party is authorized hereby to act as agent or
principal for any other party with respect to any matter related hereto.

13.13  FILES AND RECORDS.  Within thirty (30) days after the Closing Date,
       -----------------                                                  
Assignor shall deliver to Assignee copies of all material documents in
Assignor's possession pertaining to the Assets conveyed, except proprietary data
and documents subject to the attorney-client privilege.  For a period of two (2)
years after the date of Closing, Assignee will retain the books, records, and
files of Assignor delivered to it pursuant hereto and will make such books,
records, and files available to Assignor upon reasonable notice, at Assignee's
headquarters (or at such other location in the United States as Assignee may
designate in writing to Assignor), at reasonable times and during regular office
hours.

13.14  SURVIVAL OF OBLIGATIONS.  This Agreement is intended, in part, to
       -----------------------                                          
evidence the continuing rights and obligations of the parties following Closing
under this Agreement.  Accordingly, except for the representations and
warranties of the parties, all of the covenants, agreements and other
obligations of the parties expressed herein are hereby expressly made to survive
Closing of the transactions contemplated hereby.

13.15  Notwithstanding any other provisions hereof, the parties hereto agree
that Special will only acquire from Frontier those rights in the Assets that
Frontier receives pursuant to the Exchange Agreement.  Frontier will only be
required to close with Special concurrent to close with or subsequent to closing
of the Exchange Agreement at Frontier's sole discretion.  Notwithstanding any
other provisions hereof, Special will be deemed to acquire title concurrent with
Frontier acquiring its rights to the Assets such that as between Special and
Frontier it will be as if Special acquired the Assets directly from OXY for
purposes of operations.

  IN WITNESS WHEREOF, this  Agreement has been executed this 27th day of
September, 1996.

                                SPECIAL ENERGY CORPORATION

                                By         /s/ John Special
                                  -----------------------------------------
                                Its            President
                                   ----------------------------------------
 
                                FRONTIER ACQUISITION CORPORATION


                                By          /s/ David Christofferson
                                  -----------------------------------------
                                Its          Executive Vice President
                                   ----------------------------------------
<PAGE>
 
SALE AGREEMENT
PAGE 18

                                ACKNOWLEDGMENT


STATE OF OKLAHOMA }
                  } SS
COUNTY OF OKLAHOMA}

     The foregoing instrument was acknowledged before me this 27th Day of
September, 1996 by John F. Special, of Special Energy Corporation, its
President.

My Commission Expires:

4/29/98                                    /s/ Lynda F. Townsend
                                           -------------------------------
                                                Notary Public




STATE OF OKLAHOMA }
                  } SS
COUNTY OF OKLAHOMA}

     The foregoing instrument was acknowledged before me this 27th day of
September 1996, by David B. Christofferson, of Frontier Acquisition Corporation,
its Executive Vice President.

My Commission Expires:

4/29/98                                    /s/ Lynda F. Townsend
                                           --------------------------------
                                                Notary Public
<PAGE>
 
SALE AGREEMENT
PAGE 19

                                EXHIBIT "A"  -

Attached hereto and made a part of that certain Sale Agreement between Frontier
Acquisition Corporation, as Assignor and Special Energy Corporation, as
Assignee, dated September 1, 1996.

                              SCHEDULE OF LEASES
                                        
                          WEATHERFORD "A" (7-3591680)
                          ---------------------------
                                   WI: 100%
                                  NRI: 87.5%
 
  LEASE NUMBER:       63525138/3525138
  DATE OF LEASE:      December 20, 1950
  LESSOR:             Charlotte E. Plaster, now Weatherford
  LESSEE:             Cities Service Oil Company
  RECORDING DATA:     Book 339 Page 10

  DESCRIPTION:        Insofar as lease covers Lot three (3) and Lot four (4)and
                      East Half of the Southwest Quarter (E/2 SW/4), Section 31,
                      Township 4 North, Range 2 West, Garvin Co., Oklahoma

                       HOLLOWAY-WEATHERFORD (7-3540992)
                       --------------------------------
                                   WI: 100%
                                  NRI: 87.5%
 
  LEASE NUMBER:       63532136/3525138
  DATE OF LEASE:      July 10, 1943
  LESSOR:             T. S. Holloway
  LESS EE:            Harry H. Phillips
  RECORDING DATA:     Book 232 Page 140
 
  DESCRIPTION:        Northwest Quarter of Southeast Quarter, (NW/4 SE/4), North
                      Half of the Southwest Quarter of the Southeast Quarter
                      (N/2 SW/4 SE/4), Southeast Quarter of the Southwest
                      Quarter of the Southeast Quarter (SE/4 SW/4 SE/4), Section
                      31 Township 4 North, Range 2 West, Garvin Co., Oklahoma

  LEASE NUMBER:       63525138/3525138
  DATE OF LEASE:      December 20, 1950
  LESSOR:             Charlotte E. Plaster, now Weatherford
  LESSEE:             Cities Service Oil Company
  RECORDING DATA:     Book 339 Page 10
<PAGE>
 
SALE AGREEMENT
PAGE 20

  DESCRIPTION:        Insofar as lease covers Southwest Quarter of the Southwest
                      Quarter of the Southeast Quarter, (SW/4 SW/4 SE/4) Section
                      31 Township 4 North, Range 2 West, Garvin County, Oklahoma

                             BROWN "K" (7-3508880)
                             ---------------------
                                   WI: 100%
                                  NRI: 87.5%
 
   LEASE NUMBER:      63523198/3523198
   DATE OF LEASE:     December 27, 1946
   LESSOR:            Lillie C. Brown
   LESSEE:            Carl J. O'Hornet
   RECORDING DATA:    Book 268 Page 348
 
   DESCRIPTION:       Northeast Quarter (NE/4), less right-of-way for railroad;
                      North Half of the Northeast Quarter of the Southeast
                      Quarter (N/2 NE/4 SE/4); Southeast Quarter of the
                      Northeast Quarter of the Southeast Quarter (SE/4 NE/4
                      SE/4) of Section 16 Township 4 North, Range 3 West, Garvin
                      County, Oklahoma, insofar as the above lease covers all
                      rights LESS AND EXCEPT fifty percent (50%) interest from
                      surface down to the base of the Pennsylvania in the South
                      Half of Northeast Quarter (S/2 NE/4), Northwest Quarter of
                      the Northeast Quarter (NW/4 NE/4), and LESS AND EXCEPT
                      sixty-two and a half percent (62.5%) interest in the North
                      Half of the Northeast Quarter of the Southeast Quarter
                      (N/2 NE/4 SE/4) from surface to the Base of the
                      Pennsylvania formation; LESS AND EXCEPT rights from the
                      base of the Pennsylvania formation down to 100' below the
                      stratigraphic equivalent of 10,388' in the North Half of
                      the Northeast Quarter of the Southeast Quarter (N/2 NE/4
                      SE/4) and Southeast Quarter of the Northeast Quarter of
                      the Southeast Quarter (SE/4 NE/4 SE/4), LESS AND EXCEPT
                      rights into the Gibson Sand from 6949' to 7012'.

   LEASE NUMBER:      63531976/3523198
   LEASE DATE:        May 1, 1943
   LESSOR:            Edna Ruth Thompson
   LESSOR:            Harry H. Phillips
   RECORDING DATA:    Book 234 Page 368

   DESCRIPTION:       Southwest Quarter of the Northeast Quarter of the
                      Southeast 
<PAGE>
 
SALE AGREEMENT
PAGE 21

                      Quarter (SW/4 NE/4 SW/4) Section 16 Township 4 North,
                      Range 3 West, Garvin County, Oklahoma, Insofar as the
                      lease covers a thirty-seven and a half (37.5%) interest
                      from surface to the base of the Pennsylvania formation.

                          SCHEDULE OF SURFACE LEASES
                          --------------------------

  LEASE NUMBER:       S3503135
  DATE:               March 15, 1965
  LESSOR:             T. S. Holloway
  LESSEE:             Sinclair Oil & Gas Company
  RECORDING DATA:     Book 667 Page 412
 
  DESCRIPTION:        Northwest Quarter of the Southeast Quarter (NW/4 SE/4)
                      Section 31 Township 4 North, Range 2 West, Garvin Co.,
                      Oklahoma
                      
  LEASE NUMBER:       S3500786
  DATE:               October 29, 1963, amended March 19, 1985
  LESSOR:             Samie Leon Weatherford, et ux
  LESSEE:             Cities Service Oil Company
  RECORDING DATA:     Book 636 Page 394

  DESCRIPTION:        Surface of East Half of the Northwest Quarter of the
                      Southeast Quarter (E/2 NW/4 SE/4) and West Half of the
                      Northeast Quarter of the Southeast Quarter of the
                      Southwest Quarter (W/2 NE/4 SE/4 SW/4), Section 31
                      Township 4 North, Range 2 West, Disposal rights into
                      Weatherford "A" #5 well. Pipeline easement across Lots 3
                      and Lots 4 and East half of Southwest Quarter (E/2 SW/4)
                      and Southwest Quarter of the Southwest Quarter of the
                      Southeast Quarter (SW/4 SW/4 SE/4) and Southeast Quarter
                      of the Southeast Quarter of the Northwest Quarter (SE/4
                      SE/4 NW/4) of Section 31 Township 4 North, Range 2 West,
                      Garvin Co., Oklahoma


The above described Oil and Gas Leases are subject to the following:


1.  Contract 35-C-223 between Cities Service Oil Company and Erie P. Halliburton
    Co., dated Mar. 31, 1949 covering oil and gas rights in the S/2 NE/4 Sec 16
    T4N R3W, Garvin Co., Oklahoma.
<PAGE>
 
SALE AGREEMENT
PAGE 22

2.  Contract 35-C-223A between Cities Service Oil Company and Erie P.
    Halliburton Company, dated July 12, 1949 covering oil and gas rights in the
    NE/4 SE/4 Section 16 T4N R3W, Garvin Co., Oklahoma.

3.  Contract 35-C-1243 between Erie P. Halliburton and Cities Service Oil
    Company, dated November 15, 1949 covering oil and gas rights down to the
    base of the Pennsylvania Formation in NW/4 NE/4 Sec 16 T4N R3W, Garvin Co.,
    Oklahoma

4.  Oklahoma Corporation Commission Order No. 374953, dated July 1, 1993.

5.  Maysville Gasoline Plant Contract dated October 1, 1947
<PAGE>
 
SALE AGREEMENT
PAGE 23

                                 EXHIBIT "A-1"

Attached hereto and made a part of that certain Assignment between Frontier
Acquisition Corporation, as Assignor and Special Energy Corporation, as
Assignee, dated September 1, 1996.


                       ASSIGNMENT OF OIL AND GAS LEASES
                                      AND
                                 BILL OF SALE

     This Assignment of Oil and Gas Leases and Bill of Sale, effective as of
September 1, 1996 at 7:00 a.m., Daylight Standard Time, ("Effective Date"), is
by and between Frontier Acquisition Corporation, an Oklahoma Corporation, whose
address is 500 Dallas Street, Suite 2920, Houston, Texas 77002, as  "Assignor",
and Special Energy Corporation, a Texas Corporation, with a mailing address of
P. O. Drawer 369, Stillwater, Oklahoma 74076, as, "Assignee".

                             W I T N E S S E T H:

     For valuable consideration, the receipt and adequacy of which are hereby
acknowledged, Assignor hereby grants, sells, conveys, assigns and transfers to
Assignee, effective as of the Effective Date, the following:

     (a)  The interest of Assignor in the oil and gas leases thereunder as
described in Exhibit "A" attached hereto and incorporated by reference;

     (b)  All of the Assignor's right, title and interest in and under, or
derived from, all presently existing contracts, agreements and instruments to
the extent they relate to the interest described in Exhibit "A", including, but
not limited to, operating agreements, unitization agreements, communitization
and pooling agreements, agreements for the sale or purchase of oil, gas,
casinghead gas or CO\\2 \\[but excluding that certain Agreement For The Purchase
and Sale of Domestic Crude Oil executed the 31st day of August, 1983, by and
between Occidental Petroleum Corporation, et al, and CITGO Petroleum
Corporation, et al, (the "CITGO Contract")], all of which are hereinafter
collectively referred to as "Existing Contracts":

     (c)  All of Assignors right, title and interest in and to all real and
personal property (excluding vehicles), fixtures, appurtenances, easements,
licenses, approvals or authorizations and permits to the extent they directly
relate to the interests described in Exhibit "A", including all wellbores,
associated equipment, surface rights, and lease and unit owned facilities,
pipelines, treatment equipment, salt water disposal wells, compressors, tanks
and tank batteries and other fixtures.

     (d)  To the extent of the interest sold, all of Assignor's right, title
and interest in and to the oil, gas of any kind and nature, other hydrocarbons
and other minerals in, on and produced from or allocated to the leasehold
interest assigned to Assignee from and after the Effective Date hereof.

      All of the property and contract rights, titles and interests described
above are hereinafter collectively called the "Assets".

     TO HAVE AND TO HOLD the said Assets unto Assignee, its successors and
assigns, forever subject to the terms, reservations and conditions contained
herein.

     Assignee represents that it has inspected, or has sufficient opportunity to
inspect, the Assets and the premises and has satisfied itself as to their
physical and environmental condition, both surface and subsurface, and Assignee
has satisfied itself as to the risk and obligations assumed hereunder, and that
Assignee hereby accepts the same in their "AS IS, WHERE IS" condition. In
addition, all of the Assets, whether real or personal, are conveyed without
WARRANTIES OF TITLE OF ANY KIND, EITHER EXPRESS OR IMPLIED, AND WITHOUT
WARRANTIES AS TO CONDITION, MERCHANTABILITY OR FITNESS FOR 
<PAGE>
 
SALE AGREEMENT
PAGE 24


A PARTICULAR PURPOSE.

EXHIBIT "A-1"
PAGE 3

for their interests therein -- insofar as such claims relate to periods of time
prior to the Effective Time and (ii) defend, indemnify and hold Assignee
harmless from any and all such claims.  Assignee  shall be responsible d\for all
of said types of claims insofar as they relate to periods of time from and after
the Effective Time, and shall defend, indemnify and hold Assignee harmless
therefrom.

12.4   For a period of one year after the Effective Time, Assignor shall in
addition to any other obligation incurred pursuant hereto, for any claim arising
within one (1) year after the effective time defend, indemnify and hold Assignee
harmless from any and all claims in favor of any person, corporation,
partnership, government or regulatory agency, or other legal entity for personal
injury, death or damage to property or the environment, or for any other relief,
arising directly or indirectly from, or incident to, the use, occupation,
operation, maintenance or abandonment of any of the interests or conditions,
actions or inactions prior to the Effective Time.

12.5   Notwithstanding any other provision contained herein to the contrary,
Assignee acknowledges that the Assets have been utilized for the purpose of
exploration, production and development of oil and gas, and that Assignee has
been informed and is aware that oil and gas producing formations can contain
naturally occurring radioactive material (NORM) and that some oil field
production equipment and/or facilities may contain asbestos and/or NORM.
Assignee has inspected the property and premises and satisfied itself as to
their physical and environmental condition, both surface and subsurface.

12.6   In addition to provisions 12.1 and 12.2 above, to the extent that the
interest received is, or may become, a cost bearing working interest Assignee
agrees to defend, indemnify and hold harmless Assignor and its affiliated
companies, and its and their officers, directors, agents, and employees, from
and against all losses, costs, claims, demands, suits, liability and expense
with respect to the Assets which arise out of or relate to Assignee's ownership
and/or operation of such Assets.

     Assignee agrees to comply with all laws and with all rules, regulations and
orders of all municipal,  state and federal agencies and regulatory bodies in
the conduct of all operations by Assignee in and on the ;lands covered hereby,
including, but not by way of limitation, the proper plugging of all wells on the
said lands, the proper disposal or treatment of wastes and the transfer or
assumption of applicable permits, bonds, approvals and licenses.

     The provisions of this instrument and the aforementioned Exchange Agreement
shall attach to and run with the leases and lands herein described and shall be
binding upon and shall inure to the benefit of Assignor and Assignee and their
respective (as applicable) heirs, executors, administrators, successors and
assigns.

     IN WITNESS WHEREOF, the said Frontier Acquisition Corporation, as Assignor,
and Special Energy Corporation, as Assignee, have caused their names to be
affixed as of this         day of September, 1996, but this Assignment shall be
                   -------
effective as of the Effective Date herein stated.

                       ASSIGNOR

                       FRONTIER ACQUISITION CORPORATION



                       By: (AN EXHIBIT - NOT FOR SIGNATURE)
                            --------------------------------
                       Its: 
                           ---------------------------------
 
                       ASSIGNEE

                       SPECIAL ENERGY CORPORATION


                       By: (AN EXHIBIT - NOT FOR SIGNATURE)
                          --------------------------------
                       Its: 
                           --------------------------------

<PAGE>
 
EXHIBIT 99.1

                      NATURAL GAS CORPORATION LETTERHEAD
                                    (LOGO)
- --------------------------------------------------------------------------------
                                                     NEWS RELEASE   NUMBER 96-10
- --------------------------------------------------------------------------------

FOR IMMEDIATE RELEASE
- ---------------------

CONTACT:  CHARLOTTE DAY-BERRY, MANAGER - INVESTOR RELATIONS
     FRONTIER NATURAL GAS CORPORATION                          (713) 739-7100



                       FRONTIER NATURAL GAS CORPORATION
                     ANNOUNCE SALE OF N.E. CEDARDALE FIELD
                 TO OXY AND DECLARES PREFERRED STOCK DIVIDEND


HOUSTON, TEXAS - OCTOBER 7, 1996 - Frontier Natural Gas Corporation (NASDAQ:
FNGC) today announced the sale of its  N.E. Cedardale field  located in Major
County, Oklahoma to OXY USA Inc., a subsidiary of Occidental Petroleum, for
consideration totaling $3,550,000.  The properties sold represent a substantial
portion of Frontier's Oklahoma production.  The Company stated three basic
reasons for the sale:

     1)   A  favorable offer;

     2)   Divestiture of the Oklahoma properties facilitates the Company's focus
          of its resources on its Gulf Coast projects

     3)   Frontier chose to apply all of the sale proceeds to its Frontier's
          credit line with Bank of America. This reduction decreases debt
          service requirements over the next three years in an amount greater
          than the anticipated net revenues from the properties sold - thereby
          increasing net cash available to further Frontier's Gulf Coast
          projects.

Frontier indicated that the sale to OXY was for cash of $2,840,000 plus certain
exchange properties which were concurrently sold to a third party for $710,000,
thereby netting Frontier $3,550,000.  From
<PAGE>
 
News Release 96-10
October 7, 1996
Page Two

a book value basis any gain or loss on the sale  will be nominal.  The
transaction was closed  September 27, 1996 but effective September 1, 1996.

     Frontier also announced that the Board of Directors declared a quarterly
dividend of 30 cents per share on the Company's outstanding Convertible
Preferred Stock.  The dividend  will be paid October 25, 1996 to stockholders of
record at the close of business October 15, 1996.  There are now 85,961 shares
of Convertible Preferred Stock outstanding.

     Frontier has recently moved its corporate headquarters to Houston, Texas.
It has an inventory of Gulf Coast Projects.  Currently it is participating in a
3-D seismic data acquisition in Terrebonne Parish, Louisiana intended to lead to
drilling in the first quarter of 1997.  Prior to year end, Frontier plans to
commence drilling on two other Gulf Coast wells and one in the Mid-Continent
area.

     Frontier Natural Gas Corporation's primary business is exploring for
natural gas and oil utilizing 3-D seismic and other computer aided exploration
(CAEX) tools primarily along the Gulf Coast. The Company's common stock is
listed by NASDAQ in the Small Cap Issues under the symbol FNGC.


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