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                                                                  Exhibit 10.15

                               STOCK PURCHASE AGREEMENT


    THIS AGREEMENT (this "Agreement") is made and entered into this 31st day of
December, 1996, by and between ERI Investments, Inc., a Delaware corporation
(hereinafter referred to as "Purchaser"), and Costilla Energy, Inc., a Delaware
corporation (hereinafter referred to as "Seller").

                                 W I T N E S S E T H:

    WHEREAS, Seller is the owner of 1,000 shares of Common Stock, par value
$0.01 per share (the "Shares"), of Costilla Pipeline Corporation, a Texas
corporation (hereinafter referred to as "Company"), constituting all of the
issued and outstanding shares of capital stock of Company;

    WHEREAS, Seller desires to sell to Purchaser, and Purchaser desires to
purchase from Seller, the natural gas pipeline business currently conducted by
Company in the Commonwealth of Pennsylvania consisting of the assets described
in Exhibit A attached hereto (the "Assets") and certain liabilities related to
the assets as agreed to herein (all of such Assets together with such
liabilities being referred to herein as the "Business"); and

    WHEREAS, on the Closing Date, as hereinafter defined, Seller shall sell to
Purchaser, and Purchaser shall purchase from Seller, the Shares, for the
Purchase Price and upon the terms and conditions hereinafter set forth.

    NOW, THEREFORE, in consideration of the premises and mutual covenants
hereinafter contained, the parties hereto agree as follows:

                                      ARTICLE I
                             SALE AND PURCHASE OF SHARES

         1.1. SALE OF SHARES.  On the terms and subject to the conditions set
forth in this Agreement, Seller hereby agrees to sell, assign and transfer to
Purchaser, and Purchaser hereby agrees to purchase from Seller, on the Closing
Date, the Shares.

         1.2  PURCHASE PRICE AND PAYMENT.  On the Closing Date, Purchaser shall
purchase the Shares for an aggregate of Three Million Three Hundred Thousand
Dollars ($3,300,000), subject to adjustment pursuant to Section 1.3 and Section
1.4 hereof (the "Purchase Price").  The Purchase Price shall be paid on the
Closing Date by wire transfer in immediately available federal funds into an
account designated by Seller.  Seller shall designate said account at least
three (3) days prior to the Closing Date.


<PAGE>

         1.3  ADJUSTMENTS TO PURCHASE PRICE:  The Purchase Price shall be
adjusted as follows:

         a.   The Purchase Price shall be adjusted upward by the following
("Sellers' Credits"):

              (1)  The amount of all payments made by Seller in the ordinary
course of business for direct and actual (i) operating expenses, (including,
without limitation, employee expenses directly charged to the Company pursuant
to any applicable third party agreement and overhead charges under third party
agreements, but not including corporate overhead costs or employee expenses
indirectly charged to the Company or any internal general and administrative
charge(s)) and (ii) capital or maintenance expenditures under any outstanding
authority for expenditures or otherwise reasonably incurred (including, without
limitation, (x) royalties, rentals and other charges, and (y) ad valorem,
property, sales or use, and any other taxes (excluding income or profits taxes)
based upon or measured by the ownership of Assets or the receipt of proceeds
therefrom) attributable to the operation of the Company from and after the
Effective Time in accordance with generally accepted accounting principles; and

              (2)  any other amount provided for elsewhere in this Agreement or
otherwise agreed upon by Seller and Purchaser.

         b.   The Purchase Price shall be adjusted downward by the following
("Purchaser's Credits"):

              (1)  the amount of Revenues received by or credited to Seller
from or otherwise attributable to the Company after the Effective Time. For
purposes of this Section, "Revenues" shall mean the actual proceeds of sale of
natural gas transportation services sold during the period after the Effective
Time, as hereinafter defined, which are attributable to the Company and received
by or credited to Seller (or remitted by Company to Seller), and any other
monies or credits received or collected by Seller (or remitted by Company to
Seller) attributable to the ownership or operation of the Assets from and after
the Effective Time.

              (2)  the amount of all unpaid ad valorem, property, and similar
taxes and assessments (but not including income, franchise, or similar taxes)
based upon or measured by the ownership of property or the receipt of proceeds
therefrom and unpaid royalties and rentals, which are payable or which accrue to
the Company prior to the Effective Time, which amount shall, where possible, be
computed based upon the tax rate and values applicable to the tax period in
question; and

              (3)  the amount of any refunds paid by Purchaser to
transportation customers of Company for transportation service provided by
Company prior to the Effective Time which refunds are required to be paid by the
Federal Energy Regulatory Commission ("FERC") in Docket No. PR95-9.


                                       2

<PAGE>

              (4)  any other amount provided for elsewhere in this Agreement or
otherwise agreed upon by Seller and Purchaser.

         1.4  CLOSING AND POST CLOSING ACCOUNTING.  Prior to the Closing Date,
Seller shall furnish Purchaser with an estimated accounting with all relevant
supporting information (the "Preliminary Settlement Statement") showing the
estimated amount of any Seller's Credits and the estimated amount of any
Purchaser's Credits, subject to being finally adjusted within one hundred eighty
(180) days after the Closing Date as hereinafter provided. An estimated credit
due Seller shall increase the Purchase Price paid at Closing by that amount and
an estimated credit due Purchaser shall reduce the Purchase Price paid at
Closing by that amount.  Within one hundred twenty (120) days after the Closing
Date, Seller shall provide to Purchaser, for Purchaser's concurrence, an
accounting with all relevant supporting information (the "Final Settlement
Statement") of the actual amounts of Seller's and Purchaser's Credits for the
adjustments set out in Section 1.3.  Purchaser shall have the right for sixty
(60) days after receipt of the Final Settlement Statement to audit and reach
agreement with Seller on such adjustments.  The date upon which such agreement
is reached shall be herein called the Final Settlement Date.  Within ten (10)
business days after the Final Settlement Date, those credits agreed upon by
Purchaser and Seller shall be netted and the final settlement shall be paid in
cash by the party owing same, via wire transfer as directed in writing by the
receiving party or, if less than $5,000 by corporate check.

                                      ARTICLE II
                           THE CLOSING; THE EFFECTIVE TIME

         2.1  CLOSING DATE: CLOSING.

              a.   The closing hereunder (herein called the "Closing") shall
take place via telecopier and mail on December 31, 1996.  The date of the
Closing is referred to in this Agreement as the "Closing Date".

              b.   All proceedings to be taken and all documents to be executed
and delivered by all parties at the Closing shall be deemed to have been taken
and executed simultaneously and no proceedings shall be deemed taken nor any
documents executed or delivered until all have been taken, executed and
delivered.

         2.2  EFFECTIVE TIME.  The effective time of the purchase and sale
contemplated herein shall be 11:59 p.m. on December 31, 1996 (the "Effective
Time").


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                                  ARTICLE III
                           DELIVERIES AT THE CLOSING

         3.1  DELIVERIES BY SELLER.  At the Closing, Seller shall deliver, or
shall cause to be delivered, to Purchaser the following:

              a.   A certificate representing the Shares, which certificate
shall be duly endorsed in blank or, in lieu thereof, shall have affixed thereto
stock powers executed in blank, and in proper form for transfer.  In addition,
there shall be affixed to such certificates all requisite stock transfer tax
stamps, if any, or, in lieu thereof, a check from Seller to the order of
Purchaser to defray the cost of all such stock transfer taxes, if any.

              b.   The certified resolutions of the Board of Directors of
Seller referred to in Section 8.1(a) hereof.

              c.   The consents or waivers of third parties referred to in
Section 4.7 hereof

              d.   The resignations of the Directors and officers of the
Company referred to in Section 8.1(d).

              e.   The consent of Seller to the utilization by Purchaser of the
name "Three Rivers Pipeline" in the form required by the Secretary of State of
the Commonwealth of Pennsylvania.

         3.2  DELIVERIES BY PURCHASER.  At the Closing, Purchaser shall deliver
to Seller the following:

              a.   A wire transfer of funds, in the aggregate amount of the
Purchase Price, as provided in Section 1.2 hereof.

              b.   The certified resolutions of the Board of Directors of
Purchaser referred to in Section 8.2(a) hereof.

              c.   A certificate of insurance showing that Purchaser has
coverages in place for the Company and the Assets as of the Effective Time in
such types and amounts as are sufficient to ensure fully against the risks to
which the Company is normally exposed in the conduct of its operations.

                                   ARTICLE IV
                    REPRESENTATIONS AND WARRANTIES OF SELLER

    Seller hereby represents and warrants to Purchaser as follows:


                                       4

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         4.1  ORGANIZATION AND GOOD STANDING.  Each of Seller and Company is a
corporation duly organized, validly existing and in good standing under the laws
of its respective state of incorporation, and has full corporate power and
authority to own its properties and carry on its business as it is now being
conducted.  Company is duly qualified as a foreign corporation and is in good
standing under the laws of the Commonwealth of Pennsylvania.  The copies of
Company's Certificate of Incorporation and By-Laws that have been previously
delivered to Purchaser are accurate and complete.

         4.2. CAPITALIZATION.  The authorized capital stock of Company consists
of 100,000 shares of Common Stock, par value $0.01 per share, of which 1,000 are
validly issued and outstanding as of the date hereof.  All of such issued and
outstanding shares are fully paid and non-assessable.  No shares of Common Stock
are held by Company as treasury stock.  There is no existing subscription,
option, warrant, call, commitment or other right or agreement binding on Seller
or Company requiring, and there are no convertible securities of Company
outstanding which upon conversion would require, the issuance of any additional
shares of Common Stock of Company, other securities convertible into shares of
Common Stock or other equity securities of Company.

         4.3  SUBSIDIARIES.  Company does not own or control any voting shares
of any corporation. Company has no direct or indirect investment or interest in
or control over any other corporation, partnership, joint venture or other
business entity.

         4.4  OWNERSHIP OF SHARES.  Seller is the record and beneficial owner
of the Shares, free and clear of any ownership claims by third parties and any
security interests lines, charges, encumbrances pledges or rights of others. 
Seller has the corporate power and authority to enter into this Agreement, and,
the full legal right to sell, assign, transfer, and deliver to Purchaser good
and valid title to the Shares, free and clear of any and all security interests,
liens, pledges, encumbrances, charges, voting trusts, and other agreements or
claims of any kind whatsoever.

         4.5  AUTHORIZATION OF AGREEMENT.  The execution and delivery of this
Agreement and the consummation of the transactions contemplated hereby have been
duly authorized by the necessary corporate action of Seller. This Agreement has
been duly executed and delivered by Seller and constitutes the legal, valid and
binding obligation of Seller, enforceable against it in accordance with its
terms, subject to applicable bankruptcy, insolvency, fraudulent conveyance,
reorganization, moratorium, and other similar laws now or hereafter in effect
affecting creditors' rights and remedies generally and subject, as to
enforceability, to general principles of equity, including principles of
commercial reasonableness, good faith and fair dealing (regardless of whether
enforcement is sought in a proceeding at law or in equity).

         4.6  NO CONFLICTS.  The execution, delivery and performance by Seller
of this Agreement and the consummation of the transactions contemplated hereby
do not


                                       5

<PAGE>

and will not (with or without the giving of notice or the passage of time or
both) (a) conflict with or require the consent of any person or entity under the
Certificate of Incorporation, By-Laws or other governing documents of Seller,
Company or any of Seller's Subsidiaries, as the case may be, (b) violate any
provision of any law, rule or regulation applicable to Seller, Company, or the
Assets, as the case may be, (c) violate any order, judgment or decree applicable
to Seller or Company, as the case may be, (d) result in the creation of any
security interest, lien, charge or encumbrance upon the assets or properties of
Seller or Company as the case may be or (e) give rise to any preferential
purchase rights.

         4.7  CONSENTS.   No consent, approval or authorization of or
designation, declaration or filing with, any governmental authority or other
third party is required on the part of Seller in connection with Seller's
execution, delivery and performance of this Agreement, except for those
consents, approvals or authorizations that are listed in Schedule 4.7 hereto.

         4.8  REAL PROPERTY INTEREST.  Except as noted in Schedule 4.8, Company
possesses all easements, rights of way, licenses, permits, surface leases, fee
estates and other real property interests necessary to comprise a valid,
enforceable, continuous right-of-way for the Assets described in Exhibit A.

         4.9  FINANCIAL STATEMENTS.  Seller has delivered to Purchaser the
unaudited balance sheet of Company and supporting schedules, as of October 31,
1996 (the "Balance Sheet Date") (such Balance Sheet (and supporting schedules)
as of the Balance Sheet Date is herein referred to as the "Pro Forma Balance
Sheet") and the related unaudited Statement of Operations and General Ledger.
Each of the foregoing statements is in accordance with the books and records of
Company as of the date and for the periods indicated, adjusted for actual cash
receipts and payables as of the date and for the periods indicated, and present
fairly the financial position and results of operations of Company as of the
date and for the periods indicated.

         4.10 NO UNDISCLOSED LIABILITIES.  As of the Balance Sheet Date,
Company does not have any indebtedness or liability (whether accrued, absolute,
contingent or otherwise, and whether due or to become due) required to be shown
on a balance sheet prepared in accordance with GAAP (or the notes thereto) which
is not shown on the Pro Forma Balance Sheet, or expressly disclosed herein or in
a schedule hereto (whether or not such balance sheets are accompanied by notes).
Company has not incurred since the Balance Sheet Date (i) any funded
indebtedness whatsoever or (ii) any indebtedness or liability which is
outstanding on the date hereof and is required to be shown on a balance sheet in
accordance with GAAP, other than those relating to operating or capital expenses
incurred in the ordinary course of business and expressly disclosed herein or in
a Schedule hereto.


                                       6

<PAGE>

         4.11 NO MATERIAL ADVERSE CHANGE.  With respect to Company since the
Balance Sheet Date there has been no material adverse change in the Business,
Assets, liabilities, or financial condition or results of operations.

         4.12 TAXES.  All federal, state, local and foreign taxes, including,
without limitation, income, remittance, property, sales, use, franchise,
withholding, capital stock. excise, value added, employees' income withholding,
social security, and unemployment taxes, and all federal, state, or local
levies, royalties, imposts, duties, licenses and registration fees and charges
of any nature whatsoever, including with respect to all of the foregoing, any
interest and penalties thereon (all of the foregoing, including interest and
penalties, being referred to collectively as "Taxes"), for which Company may be
liable have in all respects been paid when due and payable or, with respect to
Taxes for which Company may be liable after the Balance Sheet Date, have in all
material respects been adequately accrued.  There is no action, suit,
proceeding, audit, investigation or claim pending or threatened, and to the best
knowledge of Seller, no issue relating to Taxes has been raised in writing by
the Internal Revenue Service or any other taxing authority in any examination,
in respect of any Taxes for which Company may be liable which would have a
material adverse effect on the Business, Assets or financial condition of the
Company Assets. Neither Seller nor Company (or, in the case of a Combined
Return, any corporation included in such Combined Return) has executed (or been
requested to execute) or filed with the Internal Revenue Service, or any other
taxing authority; (x) any agreement or other document extending, or having the
effect of extending, the period of assessment or collection of any Taxes, or (y)
any power of attorney with respect to Taxes.

         4.13 MATERIAL CONTRACTS.  Except as listed in Schedule 4.13, Company
is not by name, or by succession in interest bound by, or, to the best knowledge
of Seller otherwise bound by or subject to any (i) contract for the
transportation or sale of natural gas; (ii) contract for the employment of any
officer or employee or any consulting agreement; (iii) agreement for the sale or
lease of any of the Assets; (iv) contract or commitment for capital expenditures
pertaining to the Assets; (v) lease of machinery or other equipment related to
the assets; (vi) loan agreement, promissory note issued by it, guarantee,
subordination or similar type of agreement; or (vii) agreement, contract or
commitment relating to the acquisition of the assets, liabilities or any
interest in any business enterprise.  A complete and correct copy of each
agreement listed in Schedule 4.13 has been made available to Purchaser. To the
best knowledge of Seller, all contracts listed on Schedule 4.13 have been duly
authorized, executed and delivered by Company and are in full force and effect
and constitute legal binding and enforceable obligations of the Company.

         4.14 LITIGATION.

         a.  There is no lawsuit, proceeding, claim, or investigation
pending or, to the best knowledge of Seller, threatened which might question the
validity or propriety of this Agreement or the consummation of any of the
transactions contemplated hereby. There is no outstanding order, injunction,
order of any court or governmental agency 


                                       7

<PAGE>

against or naming Company materially affecting the conduct of its Businesses 
or Assets.  Neither Seller nor Company has received notice of any pending  or 
threatened (in writing) condemnation, taking or similar proceeding affecting 
any material properties owned or used by Company in the Business.

              b.   There is no lawsuit, proceeding, claim, or investigation
pending, or, to the best knowledge of Seller, threatened against Seller, its
Subsidiaries or its assets which would, if determined adversely to Seller, its
subsidiaries or assets, result in the impairment or loss of any material part of
Sellers assets (i) materially hinder or impede the operation of all or any
portion of Seller's business, or (ii) adversely affect Seller's ability to
perform its obligations under this Agreement; or (iv) materially restrain,
prohibit or impose damages on Purchaser or Company with respect to the
transactions contemplated herein.

         4.15  TITLE TO PROPERTIES: ABSENCE OF ENCUMBRANCES.  Except as shown in
Schedule 4.15, Company has good and defensible title to all properties (real and
personal) and assets reflected on the Pro Forma Balance Sheet or that comprise
the Assets, free and clear of any and all liens, mortgages, pledges, security
interests, restrictions, prior assignments, claims and encumbrances of any kind
whatsoever, except for imperfections of title, if any, as are not material in
character or amount or do not materially detract from the value or interfere
with the use of the Assets for the purposes for which they are presently used or
otherwise materially impair business operations.

         4.16  MINUTE BOOKS.   The minute books of Company, as previously made
available to Purchaser, contain complete and accurate records of all meetings
and accurately reflect all other corporate action of the stockholders and board
of directors of Company.  The stock certificate books and stock transfer ledgers
of Company are true and complete. All stock transfer taxes levied or payable
with respect to all transfers of shares of Company prior to the Closing Date
have been paid and appropriate transfer tax stamps affixed.

         4.17  EMPLOYEES AND EMPLOYEE BENEFIT PLANS.  There are no employees of
Company.  Company has no employee benefit plans or benefit arrangements in
effect which cover or provide benefits to employees of Company or Seller
("Plans").  Company has no existing or future obligation or liability with
respect to any officer or employee of Company or Seller.

         4.18  PERMITS AND COMPLIANCE WITH LAWS.  Where Company is or was
required to file for and obtain issuance of in Company's name any necessary
governmental certificates, consents, permits or authorizations, noncompliance
with which or the failure to file for and obtain issuance of which would have a
materially adverse effect upon the business, Company has satisfied such
requirements.  The books, records and accounts of Company accurately and fairly
reflect its transactions in all material respects, and Company has not directly
or indirectly made domestic or foreign payments of an illegal or questionable 
nature which would have required disclosure to its


                                       8

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stockholders, the public or to the Securities and Exchange Commission were it
subject to the reporting and filing requirements of the federal securities laws.

         4.19 COMPLIANCE WITH ENVIRONMENTAL LAWS.

              a.   Company (i) by name is not subject to any consent decree,
compliance order or administrative order issued pursuant to, or is the subject
of any pending investigation under, applicable Environmental Laws, (ii) has not
itself actually received written notice under the citizen suit provision of any
applicable Environmental Law, and (iii) has not itself actually received any
written request nor written notice of any request for information, notice of
violation, demand letter, administrative inquiry, complaint or claim from any
person, including any governmental authority, involving any alleged violation of
Environmental Laws, or the release or threatened release of any Polluting
Substances (hereinafter defined).

              b.   To the best knowledge of Seller, the ownership, operation
and use of the Assets do not violate and have not violated any Environmental
Laws.

              c.   Without limitation of (b) above, to the best knowledge of
Seller, neither the Assets nor Company are in violation of or subject to any
existing, pending or threatened (in writing) investigation or inquiry by any
Governmental Authority or to any removal or remedial obligations under any
Environmental Laws.

              d.   As used herein "Environmental Laws" shall mean all local,
state and federal laws, rules and regulations relating to pollution or
protection of the environment (including ambient air, surface water,
groundwater, land surface or subsurface strata), including, without limitation,
with respect to the Assets, the Comprehensive Environmental Response,
Compensation and Liability Act of 1976, as amended, the Toxic Substances Control
Act, the Clean Water Act, the Safe Drinking Water Act, the Clean Air Act, the
Pipeline Safety Act, the Endangered Species Act, the National Historic
Preservation Act, the Environmental Protection and Enhancement Act, and all
other laws relating to (i) emissions, discharges or releases of pollutants,
contaminants, chemicals, polychlorinated biphenyls ("PCBs", industrial solid
wastes, or toxic or hazardous substances or wastes (collectively, "Polluting
Substances") or (ii) the manufacture, processing, distribution, use, treatment,
handling, storage, disposal or transportation of Polluting Substances. 
"Governmental Authority" shall mean any federal, state, local, or other
governmental or administrative authority or agency.

         4.20  GAS IMBALANCES.  There are no material gas imbalances as between
Company and any third party with respect to the Assets.

         4.21  INSURANCE AND SURETY BONDS.  Schedule 4.21 lists all liability
insurance policies of Seller and/or Company, all property and casualty insurance
policies all of which are, to the best knowledge of Seller, now in full force
and effect.  There are no notices of any pending or, to the best knowledge of
Seller, threatened terminations


                                       9

<PAGE>

with respect to any of such insurance policies or surety bonds and to the best
knowledge of Seller, Seller and Company are in compliance with all material
conditions contained in such policies and surety bonds other than the maturity
dates set forth in such policies and surety bonds.

         4.22 ACCURACY.  Company has made available to Purchaser all of its
files, documents of title and other records regarding the Assets.  To the best
knowledge of Seller, all such files, document of title, and other records
delivered and made available to Purchaser by Seller are true and accurate all
material respects and no documents or information were intentionally omitted
therefrom that are necessary to make same not misleading in any material
respect.  Neither Seller nor Company has intentionally withheld any material
fact necessary to be disclosed in order to prevent the statements,
representations or warranties contained herein from being misleading.

         4.23 CONSULTANT AND VENDOR CONTRACTS.  Schedule 4.23 lists all
contracts entered into by Company with consultants and service vendors. All of
such contracts will be terminated at Closing without liability to Company or
Purchaser.

         4.24 PERSONAL PROPERTY.  To the best knowledge of Seller, the
machinery and equipment included in the personal property have been maintained
in accordance with customary oil and gas industry standards and practices, and
such machinery and equipment in all material respects is in working order.

         4.25 SELLER AND COMPANY FILINGS.  All filings made by Seller with the
Securities and Exchange Commission under the Securities Act of 1933, as amended
(the "Securities Act"), or the Securities Exchange Act of 1934, as amended (the
"Exchange Act") ("Seller Filings") comply as to form and otherwise in all
material respects with the applicable requirements of the Securities Act, the
Exchange Act and the rules and regulations thereunder.  None of the information
contained therein is false or misleading with respect to any material fact, or
omits to state any material fact required to be stated therein or necessary in
order to make the statements therein, in light of the circumstances under which
they were made, not misleading. To the best knowledge of Seller, no filings have
been made or are required to be made by the Company with the Securities and
Exchange Commission.

         4.26 FERC.  To the extent required by law, Company and Seller are in
compliance with the Natural Gas Act, Natural Gas Policy Act, and the Regulations
contained in 18 CFR Sections 1 ET SEQ.  The operations of Company are in
material compliance with the Statement of Conditions to Gas Transportation on
file with and approved by FERC.  With the exception of the proceeding at FERC in
Docket No. PR95-9, Seller is not aware of any proceeding, Docket, or issue at
the FERC, the resolution of which will materially effect the transaction
contemplated by this Agreement.


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<PAGE>

                                   ARTICLE V
               REPRESENTATIONS, WARRANTIES AND ACKNOWLEDGMENTS OF
                                   PURCHASER

    Purchaser hereby represents and warrants to Seller as follows:

         5.1. ORGANIZATION AND GOOD STANDING.  Purchaser is a corporation duly
organized, validly existing and in good standing under the laws of the State of
Delaware, and has full corporate power and authority to own its properties and
carry on its business as it is now being conducted.

         5.2. AUTHORIZATION OF AGREEMENT.  Purchaser has the corporate power
and authority to enter into this Agreement. The execution and delivery of this
Agreement and the consummation of the transactions contemplated hereby have been
duly authorized by the necessary corporate action of Purchaser.  This Agreement
has been duly executed and delivered by Purchaser and constitutes the legal,
valid and binding obligation of Purchaser, enforceable against it in accordance
with its terms, subject to applicable bankruptcy, insolvency, fraudulent
conveyance, reorganization, moratorium, and other similar laws now or hereafter
in effect affecting creditors' rights and remedies generally and subject, as to
enforceability, to general principles of equity, including principles of
commercial reasonableness, good faith and fair dealing (regardless of whether
enforcement is sought in a proceeding at law or in equity).

         5.3. NO CONFLICTS.  The execution, delivery and performance by 
Purchaser of this Agreement and the consummation of the transactions 
contemplated hereby do not and will not (with the giving of notice or the 
passage of time or both) (a) conflict with the Certificate of Incorporation, 
by-laws or other governing documents of Purchaser, (b) violate any provision 
of any law, rule or regulation applicable to Purchaser, (c) violate any 
order, judgment or decree applicable to Purchaser, or (d) conflict with, or 
result in a breach or default under, any agreement or other instrument to 
which Purchaser is a party or by which it may be bound.

         5.4  CONSENTS.  No consent, approval or authorization of, or
designation, declaration or filing with, any governmental authority or other
third party is required on the part of Purchaser in connection with Purchaser's
execution, delivery and performance of this Agreement.

         5.5  NO LAWSUITS.  There is not lawsuit, proceeding or investigation
pending or, to the best knowledge of Purchaser, threatened against Purchaser
which might question the validity or propriety of this Agreement or the
consummation of any of the transactions contemplated hereby.

         5.6  INVESTMENT REPRESENTATION.  Purchaser possesses such knowledge
and experience in financial and business matters that it is capable of
evaluating the merits


                                      11

<PAGE>

and risks of its investment hereunder.  Purchase is acquiring the Shares for its
own account, for investment purposes only and not with a view to the
distribution thereof.

         5.7  FINANCING.  Purchaser has sufficient funds available to pay the
Purchase Price.

         5.8  ACKNOWLEDGMENTS.

              a.   Except as and to the extent set forth in this Agreement,
Purchaser acknowledges and agrees that Seller makes no representations or
warranties whatsoever, and that Seller disclaims all liability and
responsibility for any representation, warranty, statement, or information made
or communicated (orally or in writing) to Purchaser or to any officer, employee,
agent, or representative of Purchaser (including, but not limited to, any
opinion, information, or advice which may have been provided to Purchaser by any
officer, employee, agent, consultant or representative of Seller, Company or any
of its Subsidiaries).

              b.   In determining to acquire the Shares, Purchaser has made its
own investigation, analysis, and evaluation of the Assets and Business of
Company including, without limitation limited visual on-site, inspection of the
surface of the Assets, and based thereon and on the representations, warranties,
covenants and agreements made by Seller in this Agreement, Purchaser has formed
an independent judgment concerning Company's Business, Assets, liabilities,
financial condition, results of operations, and prospects and the inherent risks
associated therewith.

              c.   Except for the representations, warranties, covenants and
indemnities made in this Agreement or in any document delivered pursuant to this
Agreement by Seller, the Assets are accepted by Purchaser "AS IS" and "WHERE
IS".

                                   ARTICLE VI
                              COVENANTS OF SELLER

         6.1  TRANSFER OF DOCUMENTS: OPPORTUNITY TO ASK QUESTIONS.   Seller
shall transfer all of Company's, and to the extent same relate directly to
Company, Sellers corporate records, books of account, property interest
documents, and all other documents reasonably requested by Purchaser and its
managerial employees within thirty (30) days after Closing.  Seller shall
further cause the managerial and staff employees, of Seller to be available upon
reasonable notice to answer questions of Purchaser's representatives concerning
the Assets and Business of Company and shall further cause them to make
available all relevant books and records in connection with such questions.  If
any questions or information requests of Purchaser shall require Seller to
utilize outside counsel or consultants, Purchaser shall reimburse Seller for the
reasonable costs and expenses of such utilization provided that Purchaser
consents to such utilization.


                                      12

<PAGE>

         6.2  NOTICE TO PURCHASER.  Seller will promptly notify Purchaser of
the receipt (a) of any written notice or written claim or written threat of
notice or claim of which Seller becomes aware relating to any default or breach
by Company, or of any termination or cancellation, or written threat of
termination or cancellation, of any of the Material Contracts (b) of any filed
or threatened litigation against the Company or the Assets, or (c) any notice,
order, or other correspondence received by Seller pertaining directly or
indirectly to an actual or alleged violation of any Environmental Law.

         6.3  CONSENTS.  Seller shall cooperate with purchaser and use
commercially reasonable efforts to obtain any other consents to the transactions
contemplated hereby.

         6.4  CONFIDENTIALITY.  After the Closing Date, Seller shall not,
directly or indirectly, use or provide to, or permit any affiliate, directly or
indirectly, to use or provide any other person any nonpublic information
concerning the Business or operations (financial or other) of Company, except,
as on the advice of counsel, Seller is required in governmental filings or
judicial, administrative or arbitration proceedings to provide said information.
Seller may disclose information concerning the sale of Company and the
consummation of the transactions contemplated herein to securities analysts,
parties providing or proposing to provide financial accommodations to Seller,
holders of Sellers' securities or prospective holders thereof and accounting,
financial petroleum engineering or other consultants to Seller having a need to
know any such information.

         6.5  PRE-CLOSING OPERATIONS.  Seller shall be solely responsible for
the Business of the Company prior to Closing, and shall undertake such measures
as are ordinarilly required for the conduct of Business including, without
limitation, the collection of revenues, payment of expenses, the preparation and
filing of reports and the maintenance of accounting records, regardless of
whether such measures are required before or after the Closing Date.

         6.6  COMPETITION.  Until the expiration of two years from Closing,
Seller, for itself or through any subsidiary, shall not engage, directly or
indirectly, alone or in association with any other party in the provision of
natural gas transportation service in the Commonwealth of Pennsylvania.

                                  ARTICLE VII.
                            COVENANTS OF PURCHASER

    Purchaser hereby covenants and agrees that:

         7.1  COOPERATION WITH SELLER.  After Closing, Purchaser shall
cooperate with Seller in providing Seller such additional information and
explanation of any materials or matters relating to the Assets, provided 
such assistance is reasonably


                                      13

<PAGE>

requested and Seller agrees to reimburse Purchaser for all out of pocket costs
that Purchaser may reasonably incur pursuant to this paragraph.

         7.2  CHANGE OF NAME.  Within thirty (30) days after the Effective
Time, Purchaser will make filings with the offices of the Secretary of State in
the State of Texas and the Commonwealth of Pennsylvania to change the name of
Company to delete "Costilla" from the name, and thereafter shall refrain from
using "Costilla" in the operation of the Company.

                                     ARTICLE VIII
                         CONDITIONS PRECEDENT TO THE CLOSING

         8.1. CONDITIONS PRECEDENT TO PURCHASER'S OBLIGATION.  The obligation
of Purchaser to consummate the purchase of the Shares on the Closing Date is
subject to the satisfaction (or waiver by Purchaser where permitted by
applicable law) of the following conditions:

              a.   RESOLUTIONS.  Purchaser shall have received a certificate of
a duly authorized officer of Seller, dated the Closing Date, setting forth the
resolutions of the Board of Directors of Seller authorizing the execution and
delivery of this Agreement and the consummation of the transactions contemplated
hereby and certifying that such resolutions were duly adopted and have not been
rescinded or amended as of the Closing Date.

              b.   THIRD PARTY CONSENTS.  The consents or waivers of those
persons listed on Schedule 4.15 hereto to the sale of the Shares to Purchaser
shall have been obtained, and signed copies thereof shall have been delivered to
Purchaser except as agreed to by Seller and Purchaser.

              c.   RESIGNATIONS.  Seller shall have delivered resignations
effective as of the Closing Date of all or directors of Company (the
"Resignations"), and certified resolutions of Company effecting the removal of
all incumbent officers of Company.

              d.   TERMINATION OF CONTRACTS.  Seller shall have delivered all
written terminations of all consulting and vendor contracts identified in
Schedule 4.23.

         8.2. CONDITIONS PRECEDENT TO SELLER'S OBLIGATION.  The obligation of
Seller to consummate the sale, transfer and assignment to Purchaser of the
Shares on the Closing Date is subject to the satisfaction (or waiver by Seller
where permitted by applicable law) of the following conditions:


                                      14

<PAGE>


              a.   RESOLUTIONS.  Seller shall have received a certificate of a
duly authorized officer of Purchaser, dated the Closing Date, setting forth the
resolutions of the Board of Directors of Purchaser authorizing the execution and
delivery of this Agreement and the consummation of the transactions contemplated
hereby, and certifying that such resolutions were duly adopted and have not been
rescinded or amended as of the Closing Date.

                                   ARTICLE IX
                      INDEMNIFICATION AND RELATED MATTERS

         9.1  INDEMNIFICATION BY SELLER.  Subject to the provisions of this
Article IX, Seller agrees to indemnify, reimburse and hold Purchaser, Company,
and their respective stockholders, directors, officers, employees, agents,
consultants and affiliates (the "Purchaser Group") harmless from and against any
and all damage, loss, cost, expense, obligation, claim or liability, including
reasonable counsel fees and expenses of investigation, defending and prosecuting
litigation (collectively the "Damages") suffered by the Purchaser Group as a
result of, caused by, arising out of, or in any way related to:

              a.   The breach of any of the representations and warranties made
by Seller in this Agreement; PROVIDED, however, that with respect to
representations and warranties made as of a specified date, it is understood
that this Section 9.1(a) shall apply only to the breach of any such
representations and warranties as of such specified date;

              b.   The failure of Seller to comply in all material respects
with any of the covenants contained in this Agreement which are required to be
performed by Seller;

              c.   Any Taxes (i) for which Seller is responsible as provided in
Section 10.1; or (ii) related to a breach or inaccuracy of Section 4.12 or the
breach of the covenants and agreements made by Seller in Article X.

              d.   Legal actions, claims, lawsuits, penalties, fines,
remediation costs and expenses relating to the environmental condition of the
Assets resulting from acts, circumstances or omissions during the period prior
to the Effective Time.

              e.   the acquisition of the Shares of Company by Seller and its
affiliates or pursuant to any agreements executed or delivered or any filings
made in connection with such acquisition.

         9.2  INDEMNIFICATION BY PURCHASER.  Subject to the provisions of this
Article IX, Purchaser agrees to indemnify, reimburse and hold Seller and its
stockholders. directors, officers, employees, agents, consultants and affiliates
(the "Seller


                                      15

<PAGE>

Group") harmless from and against any and all Damages suffered by the Seller
Group as a result of, caused by, arising out of or in any way relating to:

              a.   The breach of any of the representations and warranties made
by Purchaser in this Agreement; PROVIDED, however, with respect to
representations and warranties made as of a specified date, it is understood
that this Section 9.2(a) shall apply only to the breach of such representations
and warranties as of such specified date;

              b.   The failure of Purchaser to comply in all material respects
with any of the covenants contained in this Agreement which are required to be
performed by Purchaser; and

              c.   Except for those matters for which Seller has agreed to
indemnify the Purchaser Group the ownership and operation of the Assets after
the Adjustment Time.

         9.3  DETERMINATION OF DAMAGES. In calculating any amounts payable to
Purchaser pursuant to Section 9.1 hereof or payable to Seller pursuant to
Section 9.2 hereof, Seller or Purchaser, as the case may be, shall receive
credit for any insurance recoveries; and no amount shall be included for
Purchaser's or Seller's, as the case may be, special, consequential, or punitive
damages.

         9.4  INDEPENDENT INDEMNIFICATION OBLIGATIONS.  Each of the indemnities
and hold harmless obligations set forth in this Agreement shall be separate and
independent obligations of the party obligated and the beneficiary of the
obligation shall be entitled to make a claim pursuant to any applicable
indemnity obligation.

         9.5  LIMITATION ON INDEMNIFICATION LIABILITIES. The indemnifications
in favor of Purchaser contained in Section 9.1 hereof and the indemnifications
in favor of Seller contained in Section 9.2 hereof (a) shall not be effective
unless (i) for any single claim that is asserted, the aggregate dollar amount of
all Damages associated with any such claim exceeds $10,000 or (ii) for all
asserted claims, the aggregate dollar amount of all Damages associated with all
such claims exceeds $150,000 (in either case, the "Threshold Amount").  If
Damages exceed the Threshold Amount, the party claiming indemnification shall be
indemnified for all Damages including the initial amounts necessary to reach the
Threshold Amount.  Notwithstanding the foregoing or any other provision of this
Article IX, the respective liability of Purchaser or Seller to indemnify the
other shall not exceed the Purchase Price.

         9.6  SURVIVAL OF REPRESENTATIONS, WARRANTIES, COVENANTS, INDEMNITIES
AND AGREEMENTS.  The representations, warranties, covenants, indemnities, and
agreements made in this Agreement shall survive the Closing without limitation
as to time except as follows:


                                      16

<PAGE>

              a.   The representations and warranties made by Seller in Section
4 and the indemnity by Seller in Section 9.1(a) related to the foregoing
representations and warranties, shall only survive the Closing for the following
periods:

              (i)  for claims related to acts, omissions or circumstances
                   attributable to the period of time prior to the Effective
                   Date two (2) years after the Closing Date;

              (ii) for claims that are based on fraud attributable to Seller
                   whether or not attributable to the period prior to or after
                   the Effective Date five (5) years after the Closing Date.

              b.   The representations and warranties made by Purchaser in
Section 5 and the indemnity by Purchaser in Section 9.2(a) related to the
foregoing representations and warranties, shall only survive the Closing for the
following periods:

              (i)  for claims related to acts, omissions or circumstances
                   attributable to the period of time after the Effective Date
                   two (2) years after the Closing Date;

              (ii) for claims that are based on fraud attributable to Purchaser
                   whether or not attributable to the period prior to or after
                   the Effective Date five (5) years after the Closing Date.

         The parties hereto further agree that in order to assert a claim for
indemnification pursuant to this Agreement for a breach of any representation,
warranty, covenant or other agreement by the other party hereto, the party
seeking indemnification must provide written notice of such claim pursuant to
Section 9.7 hereof within the time periods specified by such Section, if any.

         9.7  NOTICE OF INDEMNIFICATION.  In the event any legal proceeding
shall be threatened or instituted or any claim or demand shall be asserted or
discovered by any person in respect of which payment may be sought by one party
hereto from the other party under the provisions of this Article IX, the party
seeking indemnification (the "Indemnitee") shall promptly cause written notice
of the assertion of any such claim of which it has knowledge which is covered by
this indemnity to be forwarded to the other party (the "Indemnitor"), and in the
case of indemnity the survival of which is limited, prior to the expiration of
the applicable period set forth in Section 9.6. Any notice of a claim by reason
of any of the representations, warranties, covenants, or agreements contained in
this Agreement shall state specifically the representation, warranty, covenant,
or agreement with respect to which the claim is made, the facts giving rise to
an alleged bass for the claim, and the amount of the liability asserted against
the Indemnitor by reason of the claim.


                                      17

<PAGE>

         9.8  INDEMNIFICATION PROCEDURE FOR THIRD-PARTY CLAIMS. In the event of
the initiation of any legal or administrative or other proceeding against an
Indemnitee by a third party for which indemnification is sought pursuant to this
Article IX, the Indemnitor shall have the absolute right after the receipt of
notice, at its option and at its own expense, to be represented by counsel of
its choice, and to defend against, negotiate, settle or otherwise deal with any
proceeding, claim, or demand which relates to any loss, liability or damage
indemnified against hereunder; provided, however, that the Indemnitee may
participate in any such proceeding with counsel of its choice and at its
expense.  The parties hereto agree to cooperate fully with each other in
connection with the defense, negotiation or settlement of any such legal
proceeding, claim or demand.  To the extent the indemnitor elects not to defend
such proceeding, claim or demand, and the Indemnitee defends against or
otherwise deals with any such proceeding, claim or demand, the Indemnitee may
retain counsel, at the expense of the Indemnitor, and control the defense and
settlement of such proceeding.

         9.9. EXCLUSIVE REMEDY.  The exclusive remedy available to a party
hereto in respect of the matters covered by Section 9.1 or Section 9.2 hereof
shall be to proceed in the manner and subject to the limitations contained in
this Article IX.

         9.10 BROKERS.  Seller agrees to indemnify and hold Purchaser harmless
from and against any and all liability to which Purchaser or Company may be
subjected by reason of any broker's, finder's or similar fee with respect to the
transactions contemplated by this Agreement to the extent that such fee is
attributable to any action undertaken by or on behalf of Seller. Purchaser
agrees to indemnify and hold Seller harmless from and against any and all
liability to which Seller may be subjected by reason of any broker's, finder's
or similar fee with respect to the transactions contemplated by this Agreement.

                                   ARTICLE X
                                  TAX MATTERS

         10.1 SELLER'S PRE-CLOSING TAX LIABILITY.  Seller shall be solely
responsible for the payment of all Taxes payable with respect to Company
attributable to any period ending on or before the Closing Date.  Seller shall
indemnify Purchaser from any such Taxes (including any interest and penalties
thereon) in accordance with the provisions of Section 9.1.  In the case of any
such Taxes computed for a period that includes the Closing Date but that ends
after the Closing Date, Seller shall be liable for no more than its share of
such Taxes computed on a daily basis. Seller shall provide Purchaser for its
review and concurrence draft copies of all applicable short year tax returns for
the periods ending December 31, 1996 within ninety (90) days after the Closing
Date.

         10.2 CLAIMS AND SUITS FOR REFUND.  With respect to any pending or
subsequently filed claim for refund by Company of the Taxes referenced in
Section 10.1, Purchaser agrees to notify Seller within ten days of such 
claim.  Seller will retain


                                      18

<PAGE>

complete discretion to prosecute or settle on behalf of Company each of such
claims or suits at Seller's expense.

    Purchaser further agrees to provide Seller with all reasonable cooperation
in obtaining such refunds (including the execution of appropriate powers of
attorney) and to make the records and personnel of Company available to assist
Seller or any counsel designated by Seller to prosecute any such claim or suit
for refund.

    Except as otherwise provided in Section 1.4, in the event that any refund
of Taxes for which Seller is responsible under this Agreement is received by
Purchaser or Company, Purchaser will pay to Seller within fifteen days an amount
equal to such refund plus any interest received on such refund, provided,
however, that Purchaser shall retain any such refund to the extent it is
attributable to the carryback of any item that arose in a period following the
Closing.

         10.3 ASSISTANCE AND RECORDS.  Purchaser shall provide Seller with
assistance as Seller may reasonably request in connection with tax returns or
administrative or judicial action proceedings involving Seller and Company. 
Such assistance shall include making employees available to Seller and its
counsel, providing additional information and explanation of any material to be
provided, and furnishing relevant materials.  Seller will retain complete
discretion in conducting and resolving any audit or administrative or judicial
proceeding relating to any Taxes with respect to periods ending on or before the
Closing Date.  Purchaser will notify Seller within five days of any such matter
that could affect Seller's Tax liability.  Purchaser will retain and, upon the
request of Seller, provide any records or information that may be relevant to
such matter.  Seller agrees to reimburse Purchaser for all out of pocket costs
that Purchaser may reasonably incur pursuant to this paragraph.

                                   ARTICLE XI
                                    EXPENSES

         11.1 REGULATORY EXPENSES.  Purchaser shall be responsible for, and
bear all costs related to preparing and prosecuting all filings, pleadings and
applications to the Public Utility Commission of Pennsylvania the FERC and any
other regulatory agency as may be required to receive such authorizations as are
necessary to effectuate the terms of this Agreement.

         11.2 TRANSACTION EXPENSES.  Each party shall be solely responsible for
all expenses incurred by it in connection with this transaction (including, but
not limited to fees and expenses of its counsel, accountants, brokers, and
finders) and shall not be entitled to any reimbursement therefore from the other
party, except as otherwise provided herein.  Sales, use, and transfer taxes
(excluding taxes on gross income, net income or gross receipts), as well as
duties, levies or other governmental charges imposed with respect to transfers
undertaken pursuant to this Agreement shall be shared equally by Buyer and
Seller.


                                      19

<PAGE>

                                  ARTICLE XII
                            POST-CLOSING ASSISTANCE

         12.1 POST CLOSING ASSISTANCE.  Purchaser may require certain 
services from Seller for up to 180 days after Closing. Purchaser and Seller 
may execute a separate service agreement which sets forth the services to be 
provided by Seller and the manner of compensation from Purchaser.  The 
execution or non-execution of such service agreement shall not effect the 
obligations of the Purchaser and Seller to cooperate and exchange information 
under this Agreement.

                                  ARTICLE XIII
                                    GENERAL

         13.1 SPECIFIC PERFORMANCE.  The parties hereto acknowledge that
irreparable damage would result if this Agreement is not specifically enforced.
Therefore, the rights and obligations of the parties under this Agreement,
including, without limitation, their respective rights and obligations to sell
and to purchase the Shares, shall be enforceable by a decree of specific
performance issued by any court of competent jurisdiction, and appropriate
injunctive relief may be applied for and granted in connection therewith.  Such
remedies shall, however, be cumulative and not exclusive and shall be in
addition to any other remedies which any party may have under this Agreement or
otherwise if this Agreement shall be breached prior to the consummation of the
transactions contemplated hereby.

         13.2 NOTICES.  Any notices or other communications required or
permitted hereunder shall be in writing and shall be deemed to have been duly
given when delivered personally or transmitted by telecopier, receipt
acknowledge, or in the case of documented overnight delivery service or
registered or certified mail, return receipt requested, postage prepaid, on the
date shown on the receipt therefor:

         a.   if to Purchaser:
         ERI Investments, Inc.
         911 Washington Street
         Wilmington, Delaware
         Attn: Treasurer
         Telecopy No.: (302) 428-1410

         with a copy to: 
         Equitrans, L.P.
         3500 Park Lane
         Pittsburgh, PA 15071
         Attn: Frank H. Markle
         Telecopy No. (412) 553-6563


                                      20

<PAGE>

         b.   if to Seller:
         Costilla Energy, Inc.
         P. O. Box 10369
         Midland, TX 79702
         Attn: Henry G. Musselman
         Telecopy No. (915) 686-6081

         13.3 AMENDMENTS.  This Agreement may be amended, modified, superseded
or canceled and any of the terms, covenants, representations, warranties, or
conditions hereof may be haired only by an instrument in writing signed by each
of the parties hereto or, in the case of a waiver, by or on behalf of the party
waiving compliance.

         13.4 ENTIRE AGREEMENT.  This Agreement, including the schedules
hereto, any written amendments to the foregoing satisfying the requirements of
Section 12.3 hereof, and the Confidentiality Agreement and Letter Agreement
referred to in Section 5.3 hereof, constitute the entire agreement among the
parties with respect to the subject matter hereof and thereof, and supersede any
previous agreements and understandings between the parties with respect to such
matters.

         13.5 SUCCESSORS.  This Agreement shall be binding upon and shall inure
to the benefit of the parties hereto and their respective successors and
assigns, including, without limitation, successors and assigns to all or any
portion of the Assets.

         13.6 HEADINGS.  The Article and Section headings contained in this
Agreement are for reference purposes only and shall not affect in any way the
meaning or interpretation of this Agreement.

         13.7 JURISDICTION: CONSENT TO SERVICE OF PROCESS.  THIS AGREEMENT
SHALL BE GOVERNED BY, CONSTRUED AND ENFORCED IN ACCORDANCE WITH THE LAWS OF THE
COMMONWEALTH OF PENNSYLVANIA.

         13.8 EXPENSES.  Whether or not the transactions contemplated hereby
are consummated, the parties hereto shall pay their oven respective expenses.

         13.9 SEVERABILITY.  If at any time subsequent to the date hereof, any
provision of this Agreement shall be held by any court of competent jurisdiction
to be illegal, void or unenforceable, such provision shall be of no force and
effect, but the illegality or unenforceability of such provision shall have no
effect upon and shall not impair the enforceability of any other provision of
this Agreement.

         13.10  PUBLIC ANNOUNCEMENTS.  Neither Seller (nor any of its 
affiliates) nor Purchaser (nor any of its affiliates) shall make any public
statements, including,


                                      21

<PAGE>

without limitation, any press releases, with respect to this Agreement and the
transactions contemplated hereby without the prior written consent of the other
party (which consent may not be unreasonably withheld), except as may be
required by law or listing agreements with national securities exchanges and
then only after prior consultation with the other party.

         13.11  FURTHER ASSURANCES.  From and after the Closing Date,
Purchaser and Seller shall take such further action and execute any instruments
and documents reasonably necessary to carry out the purposes of this Agreement
or any document delivered or executed in connection with this Agreement.

         13.12  COUNTERPARTS.  This Agreement may be executed in one or more
counterparts, each of which shall be deemed and original, but all of which taken
together shall constitute one and the same instrument.

    IN WITNESS WHEREOF, the parties hereto have duly executed this Agreement,
as of the date first written above.

                             COSTILLA ENERGY, INC.


                             By  /s/  HENRY G. MUSSELLMAN
                               ----------------------------------------
                             Name: Henry G. Musselman
                             Title:  Executive Vice President


                             ERI INVESTMENTS, INC.


                             By  /s/  JEFFREY C. SWOVELAND
                               ----------------------------------------
                             Name: Jeffrey C. Swoveland
                             Title:  President




                                      22

<PAGE>

                                  EXHIBIT "A"
                             ASSETS TO BE ACQUIRED

    The Assets conveyed and acquired herein consist of all of the following:

(a) that certain 8-inch approximately 122 mile pipeline extending from a
    point where the pipeline crosses the Airco Arroyo 20" nitrogen line
    southeast of the Ohio River near Midland, Pennsylvania, to a point of
    interconnection with Peoples Natural Gas near Hollidaysburg,
    Pennsylvania, including without limitation, the 4-inch lateral line
    extending from the 8-inch line to McKees Rocks, Pennsylvania in
    Allegheny County, all as shown on the map attached hereto as Exhibit
    "A-l" (the "Pipeline"); 

(b) all rights-of-way, servitudes and easements across, over and through
    properties which the Pipeline is located;

(c) all properties held in fee all surface leases and other real property
    rights and interests used or useful in, or incident to, the
    construction, ownership or operation of the Pipeline;

(d) all licenses, permits and approvals incident to, or used or useful in
    connection with the ownership, construction or operation of the
    Pipeline;

(e) all equipment, facilities buildings and other improvements, pipe, pipe
    racks, pumps, engines, compressors, separators, block valves, heaters,
    measurements and pigging facilities, tanks and other equipment,
    warehouse stocks of pipe, spare parts and all other personal property
    of every kind located on the properties herein conveyed, appurtenant
    thereto or used or useful in connection with the construction,
    ownership or operation of the Pipeline or any of the other Assets;

(f) any and all contractual rights, warranties and guarantees in favor of
    Seller which affect the ownership or operation of the Pipeline or any
    of the other assets herein conveyed;

(g) any and all files, books and records relating to the construction,
    ownership or operation of the Pipeline. including, without limitation
    all files pertaining to rights-of-way environmental compliance,
    construction, claims and causes of actions or governmental
    proceedings.

(h) the trade and business name "Three Rivers Pipeline" and derivatives
    thereof, together with all marks, logos and symbols relating thereto.