<PAGE>

                                                                   EXHIBIT 10.11


                THIRD AMENDMENT TO SECOND AMENDED AND RESTATED
                       LIMITED PARTNERSHIP AGREEMENT OF
                          ARGOSY ENERGY INTERNATIONAL

     THIS THIRD AMENDMENT TO THE SECOND AMENDED AND RESTATED LIMITED PARTNERSHIP
AGREEMENT OF ARGOSY ENERGY INTERNATIONAL, AS PREVIOUSLY AMENDED (this
"Amendment") is made and entered into to be effective as of the 31st day of May,
 ---------
2000, by and among the partners (collectively the "Partners") of Argosy Energy
                                                   --------
International, a Utah limited partnership (the "Partnership").
                                                -----------

                                   RECITALS

     WHEREAS, Argosy Energy Incorporated, a Delaware Corporation (the "General
                                                                       -------
Partner"), Parkside Investments, a Utah corporation ("Parkside"), P-5, Ltd., a
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Utah limited partnership ("P-5"), Go Deo, Inc., a Utah corporation ("Go Deo"),
                           ---                                       ------
Dale E. Armstrong ("Armstrong"), William Gaskin ("Gaskin"), Richard Shane
                    ---------                     ------
McKnight ("McKnight") and Garnet Resource Corporation, a Delaware corporation
           --------
("Garnet") entered into that certain Second Amended and Restated Limited
  ------
Partnership Agreement of Argosy Energy International dated January __, 1991, as
amended by the Amendment to the Second Amended and Restated Limited Partnership
Agreement of Argosy Energy International dated January 13, 1994 and the Second
Amendment to the Second Amended and Restated Limited Partnership Agreement of
Argosy Energy International dated July 1, 1994 (as amended, the "Original
                                                                 --------
Partnership Agreement");
---------------------

     WHEREAS, on March 16, 1995, Garnet acquired though multiple conveyances all
of the limited partnership interests in and to the Partnership previously owned
by Parkside, P-5 and Go Geo;

     WHEREAS, on February 12, 1996, Gaskin assigned all of his limited
partnership interests in and to the Partnership to the General Partner, Garnet,
Armstrong and McKnight;

     WHEREAS, effective January 1, 1999, Neo Energy, Inc. ("Neo") acquired by
                                                            ---
contribution of property to the Partnership a 49.9054% limited partnership
interest in and to the Partnership, which resulted in a corresponding decrease
in the percentage interests of Garnet, Armstrong and McKnight;

     WHEREAS, pursuant to Section 13.1 of the Original Partnership Agreement,
the undersigned Partners, which comprise the requisite percent of Partners
needed to amend the Original Partnership Agreement, desire to amend the Original
Partnership Agreement pursuant to the terms of this Amendment; and

     WHEREAS, the Partners intend that all provisions of the Original
Partnership Agreement not otherwise amended pursuant to the terms of this
Amendment shall remain in full force and effect.
<PAGE>

     NOW, THEREFORE, in consideration of the premises and other good and
valuable consideration, the receipt of which is hereby acknowledged, the
Partners hereby agree as follows:

1.   Article I Amendments. Article I of the Original Partnership Agreement is
     ---------------------
hereby amended by deleting Article I in its entirety and replacing it with the
following Article I, which shall read in its entirety as follows:

                                       I

                            THE LIMITED PARTNERSHIP

          1.1  Formation.

          The Partnership was previously formed, as memorialized by that certain
     Certificate of Limited Partnership ("Certificate"), which was filed in the
                                          -----------
     appropriate governmental office in Salt Lake City, Salt Lake County, Utah,
     in order to maintain and perfect the Partnership's existence as a limited
     partnership under Utah law. The Partners shall make any and all necessary
     or appropriate amendments to the Certificate which are required as a result
     of the execution of this Agreement.

          1.2  Name of Partnership.

          The name of the Partnership is ARGOSY ENERGY INTERNATIONAL.

          1.3  Term.

          The Partnership shall continue in existence until the close of
     business on December 31, 2025, unless earlier terminated in accordance with
     the terms of this Agreement.

          1.4  Purposes of Partnership.

          The purposes of the Partnership are as follows:

               (a)  To invest in, explore for, produce, treat, transport, market
          and sell oil and gas, or products derived therefrom, on and from the
          property described on Exhibit "A" hereto (the "Property"), which by
                                                         --------
          this reference is made a part hereof, located within the Republic of
          Colombia, S.A. and to engage directly or indirectly in any other
          business activity that lawfully may be conducted by a limited
          partnership organized under the laws of the State of Utah.

               (b)  In furtherance of said business, the Partnership shall
          acquire any and all assets and engage in and carry out any business
          whatsoever that the General Partner shall deem proper or convenient in
          connection with any of the foregoing purposes, or which it deems
          necessary or appropriate to improve or assist in the business of the
          Partnership, to exercise all powers conferred by the laws of the State
          of Utah on limited partnerships formed under the laws of that

                                       2
<PAGE>

          state, as such laws are now in effect or may at any time hereafter be
          amended, and to do any and all things herein above set forth to the
          same extent and as fully as natural persons might or could do, either
          alone or in connection with other persons, firms, partnerships,
          associations, or corporations.

          1.5  Place of Business.

          The principal place of business of the Partnership shall be located
     at, and the address of the Partnership shall be, 8235 Douglas Avenue, Suite
     400, Dallas, Texas 75225, or such other or additional place or places as
     shall be designated from time to time by the General Partner.

          1.6  Names and Addresses of Partners.

          The names and addresses of the General Partner and the Limited
     Partners (collectively, the "Partners") are as set forth on Exhibit "B"
                                  --------
     hereto which by this reference is made a part hereof. A Partner may change
     his or its address by giving written notification to the General Partner as
     provided herein.

          1.7  Definitions.

          For purposes hereof, the following terms shall have the following
     meanings:

          (a)  "Adjusted Capital Account Deficit" means, with respect to any
                --------------------------------
     Partner for any taxable year, the deficit balance, if any, in such
     Partner's Capital Account as of the end of such taxable year, as the same
     is specially computed to reflect the adjustments required or permitted to
     be taken into account in applying Treasury Regulations Section 1.704-
     1(b)(2)(ii)(d) (including adjustments for Partnership Minimum Gain and
     Partner Nonrecourse Debt Minimum Gain).

          (b)  "Affiliate" means, when used with reference to a specified
                ---------
     individual or entity, any individual or entity that, directly or indirectly
     through one or more intermediaries, controls, is controlled by, or is under
     common control with the specified individual or entity; provided, however,
     that no individual or any entity who controls, is controlled by, or is
     under common control with such individual shall be deemed an Affiliate of
     another entity solely by reason of such individual's status as a director,
     officer or employee of such entity. As used in this definition of
     Affiliate, the term "control" means the possession, directly or indirectly,
                          -------
     of the power to direct or cause the direction of the management and
     policies of an individual or entity, whether through ownership of voting
     securities, by contract or otherwise.

          (c)  "Book Basis" means, with respect to any asset, the asset's
                ----------
     adjusted basis for federal income tax purposes; provided, however, (a) if
     property is contributed to the Partnership, the initial Book Basis of such
     Property will equal its fair market value on the date of contribution, and
     (b) if the Capital Accounts of the Partnership are adjusted pursuant to
     Treasury Regulation Section 1.704-1(b) to reflect the fair market value of
     any Partnership assets, the Book Basis of such assets will be adjusted to
     equal its respective fair market value as of the time of such adjustment in
     accordance with such Treasury

                                       3
<PAGE>

     Regulation. The Book Basis of all assets of the Partnership shall be
     adjusted thereafter by depreciation or amortization as provided in Treasury
     Regulation Section 1.704-1(b)(2)(iv)(g).

          (d)  "Code" means the Internal Revenue Code of 1986, as amended from
                ----
     time to time.

          (e)  "Dollar Revenues" means the revenues received by the Partnership
                ---------------
     for the sale of production and any other revenues received by the
     Partnership that are paid in U.S. Dollars.

          (f)  "General Partner" means Argosy Energy Incorporated and its
                ---------------
     permitted successors and assigns.

          (g)  "Limited Partner" means those Partners listed as limited partners
                ---------------
     on Exhibit B, and their permitted successors and assigns.

          (h)  "Net Profit" and "Net Loss" mean for each taxable year or other
                ----------       --------
     period the excess of items of Profit over items of Loss for such period, or
     the items of Loss over the items of Profit for such period, as appropriate.
     The terms Net Profit and Net Loss shall not include items of Profit and
     Loss allocated pursuant to Section 7.2.

          (i)  "Partners" mean the General Partner and Limited Partners.
                --------

          (j)  "Partnership Minimum Gain" has the meaning set forth in Treasury
                ------------------------
     Regulation Section 1.704-2(b)(2).

          (k)  "Partner Minimum Gain" has the meaning set forth in Treasury
                --------------------
     Regulation Section 1.704-2(i)(2).

          (l)  "Partner Nonrecourse Debt" has the meaning set forth in Treasury
                ------------------------
     Regulation Section 1.704-2(b)(4).

          (m)  "Pesos Revenues" means the revenues received by the Partnership
                --------------
     for the sale of production and any other revenues received by the
     Partnership that are paid in Colombian Pesos.

          (n)  "Profits" and "Losses" mean, for each taxable year or other
                -------       ------
     period, an amount equal to the Partnership's taxable income or loss for the
     year or other period, determined in accordance with Section 703(a) of the
     Code (including all items of income, gain, loss or deduction required to be
     stated separately under Section 703(a)(1) of the Code), with the following
     adjustments:

               (i)   Any income of the Partnership that is exempt from federal
          income tax and not otherwise taken into account in computing Profits
          or Losses will be added to taxable income or loss;

                                       4
<PAGE>

               (ii)  Any expenditures of the Partnership described in Section
          705(a)(2)(B) of the Code or treated as Section 705(a)(2)(B)
          expenditures under Treasury Regulation Section 1.704-1(b)(2)(iv)(i),
          and not otherwise taken into account in computing Profits or Losses,
          will be subtracted from taxable income or loss;

               (iii) Gain or loss resulting from any disposition of Partnership
          property with respect to which gain or loss is recognized for federal
          income tax purposes will be computed by reference to the Book Basis of
          the property, notwithstanding that the adjusted tax basis of the
          property differs from its Book Basis;

               (iv)  Any depreciation, amortization and other cost recovery
          deductions shall be subject to the rules set forth in Treasury
          Regulation Section 1.704-1(b)(2)(iv)(g); and

               (v)   Profits or Losses of the Partnership shall be computed
          without regard to the amount of any items of gross income, gain, loss
          or deduction that are specially allocated under Section 2 hereunder.

          (o)  "Stated Rate" means the prime rate of interest as published from
                -----------
     time to time in the Wall Street Journal plus 1%.

2.   Article II Amendments. Article II of the Original Partnership Agreement is
     ---------------------
hereby amended as follows:

     A.   Sections 2.1(a), (b), (c), (e) of the Original Partnership Agreement
are hereby  deleted in their  entirety and replaced with the following  Sections
2.1(a),  (b),  and (c),  respectively,  which each shall read in its entirety as
follows:

          (a)  Enter into, make, perform and amend existing and future
     contracts, joint venture agreements, undertakings, commitments, leases and
     agreements, including, without limitation, any such contracts with Empresa
     Colombiana de Petroleos ("Ecopetrol"), and do such other acts as it may
                               ---------
     deem necessary or advisable, or as may be incidental to, or necessary for,
     the conduct of the business of the Partnership and the ownership,
     management, development and sale of the property of the Partnership,
     whether owned directly or with any other person, firm, corporation, or
     other entity having any business, financial, or other relationship with the
     General Partner;

          (b)  Open, maintain and close bank accounts and draw checks and other
     orders for the payment of money thereupon;

          (c)  Borrow or loan money and make, issue, accept, endorse and execute
     promissory notes, drafts, bills of exchange, and other instruments and
     evidences of indebtedness for amounts not to exceed six million six
     hundred-thousand dollars ($6,600,000); and pay or repay with respect
     thereto, and secure the payment thereof by mortgage, security deed, pledge,
     or assignment of, or security in, all or any part of any property then
     owned or thereafter acquired by the Partnership, whether directly or

                                       5
<PAGE>

     indirectly, and prepay, refinance, increase, modify, consolidate or extend
     any mortgage, security deed, or other encumbrance or security device;

     B.   Section 2.1(d) of the Original Partnership Agreement is hereby deleted
in its entirety.

     C.   Sections 2.1(f), (g), (h), (i), (j), and (k) of the Original
Partnership Agreement are hereby re-lettered as (e), (f), (g), (h) and (i)
respectively.

     D.   Section 2.2 of the Original Partnership Agreement is hereby deleted in
its entirety and replaced with the following Section 2.2 which shall read in its
entirety as follows:

          2.2  Restrictions on the General Partner.

          (a)  Notwithstanding anything to the contrary contained elsewhere in
     this Agreement, the General Partner shall not have authority to do any of
     the following in its name or in the name or on behalf of the Partnership,
     without the written consent or ratification of the specific act by all of
     the Limited Partners:

               (i)   Any act in contravention of this Agreement;

               (ii)  Any act that would make it impossible to carry on the
          ordinary business of the partnership ;

               (iii) Confess a judgment against the Partnership; or

               (iv)  Possess Partnership assets, or assign rights in specific
          Partnership assets, for purposes other than a Partnership purpose;

          (b)  Notwithstanding anything to the contrary contained elsewhere in
     this Agreement, the General Partner shall not have the authority to do any
     of the following in the name or on behalf of the Partnership, without the
     written consent or ratification of the specific act by Partners owning at
     least eighty percent (80%) of the Percentage Interests in the Partnership:

               (i)   any sale, exchange, lease, or disposal of any of the
          Partnership's assets having a value of more than $2,000,000 in a
          single transaction or a series of related transactions;

               (ii)  any merger or consolidation of the Partnership with any
          Affiliate entity of the General Partner;

               (iii) any purchase, exchange or other acquisition of any assets
          having a value of more than $2,000,000 in single transaction or a
          series of related transactions;

               (iv)  any agreement to any indebtedness, encumbrance or liability
          in excess of $6,600,000;

                                       6
<PAGE>

               (v)    the issuance of any additional Partnership interests in
          the Partnership without first providing the existing Partners the
          right to acquire such additional Partnership interests on the same
          terms and conditions in proportion to their existing Percentage
          Interests;

               (vi)   any quitclaim, surrender, release or abandonment of any
          Partnership property or interests therein except in the ordinary
          course of business;

               (vii)  the guarantee of the payment of money or the performance
          of any contract or obligation by any person on behalf of the
          Partnership;

               (viii) the loan of money to a Partner or any third party;
          provided, however, that the consent of the Limited Partners to any
          such loan at the request of another Partner or Partners shall not be
          unreasonably withheld;

               (ix)   the bringing of suit in the name of or in behalf of the
          Partnership or the settlement, waiver or compromise of any suit
          brought by or on behalf of or against the Partnership where the amount
          in controversy is in excess of $500,000;

               (x)    the confession of a judgment against the Partnership;

               (xi)   the submission of a Partnership claim or liability to
          arbitration or reference where the amount in controversy is in excess
          of $500,000; and

               (xii) any alterations to the apportionment, between United States
          dollars and Colombian pesos, of payments under the operating agreement
          for the Santana concession, whose ratio currently stands at 75%
          dollars and 25% pesos.

     E.   Sections 2.3, 2.4, 2.5, 2.6, 2.7, 2.8 and 2.9 of the Original
Partnership Agreement are deleted in their entirety and replaced with the
following Sections 2.3, 2.4, 2.5, 2.6, 2.7, 2.8 and 2.9 respectively, which
shall read each in its entirety as follows:

          2.3  Compensation of General Partner.

          The General Partner shall be reimbursed by the Partnership for the
     direct out-of-pocket expenses reasonably incurred by it on behalf of the
     Partnership under the authority granted in this Agreement. All claimed
     reimbursable expenses shall be supported by vouchers, checks or other
     documentation. The Partners hereby authorize the General Partner to enter
     into a services agreement for general administrative services of the
     Partnership not to exceed seventy-five thousand dollars ($75,000) per
     month, but otherwise upon the terms and conditions determined by the
     General Partner in its sole discretion.

          2.4  Liability of General Partner.

          The General Partner, its members, managers, officers, agents and
     employees shall not be liable, responsible or accountable, in damages or
     otherwise, to the Partnership or to the Limited Partners for any action
     taken or failure to act on behalf of the Partnership

                                       7
<PAGE>

     within the scope of the authority conferred upon the General Partner by
     this Agreement or by law, unless such action or omission was performed or
     omitted fraudulently or constituted gross negligence.

          2.5  Indemnification of General Partner.

          The Partnership shall and hereby does indemnify and hold harmless the
     General Partner and its members, managers, officers, directors, agents,
     attorneys and employees from and against any losses, expenses, or
     liabilities attributable to their acts or damages or other omissions or
     alleged acts or omissions occurring in the course of their activities on
     behalf of the Partnership or in furtherance of the business of the
     Partnership, including, but not limited to, any judgment, award,
     settlement, reasonable attorneys' fees and other costs or expenses incurred
     in the defense of any actual or threatened action, proceeding or claim;
     provided that the acts or omissions or alleged acts or omissions, upon
     which the actual or threatened action, proceeding or claim is based,
     occurred in good faith and were not performed or omitted fraudulently or
     did not constitute gross negligence. To the extent such acts or omissions
     occurred in bad faith, were fraudulent or constituted gross negligence, the
     indemnity provided under this Section 2.5 shall be reduced by the General
     Partner's share of such bad faith, fraudulent or grossly negligent action,
     but shall otherwise not be eliminated.

          2.6  No Exclusive Duty to Partnership.

          Neither the General Partner nor any affiliate of the General Partner
     shall be required to devote its full time, resources, or attention to the
     affairs and business of the Partnership, but shall devote such part of
     their time, effort and skill as they shall reasonably deem necessary to
     further conduct the Partnership's business in accordance with this
     Agreement and in accordance with the terms and provisions of the agreements
     governing the Partnership's ownership and operation of the Property. The
     General Partner and all other Partners may, notwithstanding the existence
     of this Agreement, engage in whatever other business activities outside the
     Republic of Colombia, South America, as they may choose, whether the same
     be competitive with the Partnership or otherwise, without having or
     incurring any obligation to offer any interest in such other activities to
     the Partnership or to the other Partners. It is expressly agreed that any
     Partner who engages in other business activities outside the Republic of
     Colombia, South America, shall not be considered to have breached any
     fiduciary or other duty that such Partner may have to the Partnership or to
     the other Partners.

          2.7  Partnership Opportunities.

          Any and all business opportunities within the Intendancy of Putumayo,
     or the Department of Cauca, of the Republic of Colombia, South America,
     which come to the attention of any Partner shall be deemed an opportunity
     of the Partnership (a "Partnership Opportunity") and shall be immediately
                            -----------------------
     presented to the Partnership. If Partners owning at least 80% of the
     Percentage Interests vote in favor of pursuing a Partnership Opportunity,
     no individual Partner may pursue such Partnership Opportunity. In the event
     that Partners owning at least 80% of the Percentage Interests do not vote
     in

                                       8
<PAGE>

     favor of pursuing a Partnership Opportunity, any individual Partner
     (including the General Partner) may pursue such opportunity in his or its
     own right, unless otherwise prohibited pursuant to the terms of another
     agreement.

          2.8  Conversion of General Partner.

          In the event that the General Partner shall fail or refuse to carry
     out its duties hereunder or become incapable of carrying out its duties
     hereunder, the General Partner may be converted to a limited partner upon
     the vote of Partners (other than the General Partner) owning 80% of the
     Percentage Interests (as defined in Section 5.1) in the Partnership
     (exclusive of the General Partner's Percentage Interest in the
     Partnership), provided, however, that no such conversion shall affect the
     Capital Account, Percentage Interests or distribution rights of such
     General Partner or any other Partner. Upon removal, as provided for by this
     Section 2.8, the General Partner so removed shall become and shall continue
     as a Limited Partner of the Partnership.

          2.9  Withdrawal of General Partner.

          The General Partner may withdraw as General Partner and convert its
     interest to a Limited Partner at any time upon ninety (90) days' prior
     written notice to each of the Partners. Such notice shall set forth the
     effective date of such withdrawal and conversion and shall contain the
     General Partner's recommendation as to its successor, if any. The General
     Partner shall use its best efforts to find a successor, if requested to do
     so by the Partnership, who has indicated a willingness to serve as the
     General Partner under the terms of this Agreement. The withdrawal and
     conversion by the General Partner shall in no way affect the Capital
     Account, Percentage Interests or distribution rights of the General
     Partner, and the General Partner shall become and shall remain a Limited
     Partner of the Partnership.

3.   Article III Amendments. Article III of the Original Partnership Agreement
     ----------------------
is hereby amended by deleting Sections 3.1, 3.2, 3.3 and 3.4 in their entirety
and replacing them with the following Sections 3.1, 3.2, 3.3 and 3.4, which
shall read each in its entirety as follows:

          3.1  Liability and Control.

          Except as provided in Section 3.3, the liability of each Limited
     Partner shall be limited to his or its contribution to the capital of the
     Partnership and he or it shall have no other liability. Except as permitted
     by Utah law and this Agreement, the Limited Partners shall take no part
     whatsoever in the control, management, direction or operation of the
     affairs of the Partnership and shall have no power to bind the Partnership.
     At all times, the sole control and management of the Partnership shall rest
     with the General Partner unless this Agreement or Utah law requires the
     Limited Partners to participate in or consent to a particular decision.

          3.2  Representation of Limited Partner.

          Each Limited Partner, by executing this Agreement and becoming a party
     hereto, represents that his or its interest in the Partnership was acquired
     for his or its own

                                       9
<PAGE>

     account, for investment purposes only and not with a view to, or for sale
     in connection with, any distribution of any part or portion thereof. Each
     Limited Partner acknowledges and agrees that the sale or transfer of his or
     its interest in the Partnership is severely restricted by the terms of this
     Agreement.

          3.3  Liability for Repayment of Distributions.

          To the extent required by Utah law, a Limited Partner shall be liable
     and hereby agrees to repay to the Partnership the amount of any
     distribution made to such Limited Partner hereunder in the event that such
     repayment becomes necessary in order for the Partnership to discharge its
     liabilities to creditors who extended credit to the Partnership, or whose
     claims arose before such distribution.

          3.4  No Priority in Return of Capital.

          Except as may be otherwise set forth in Articles VII and VIII hereof,
     no Limited Partner shall have priority over another Limited Partner, either
     as to contributions to capital or as to sharing in the profits or losses of
     the Partnership. No Limited Partner shall have the right to receive
     property other than cash in return for his or its contribution to the
     capital of the Partnership.

4.   Article IV Amendments.  Article IV of the Original Partnership Agreement is
     ---------------------
hereby amended by deleting Sections 4.1, 4.2, and 4.3 in their entirety and
replacing them with the following Sections 4.1, 4.2, and 4.3, respectively,
which shall read each in its entirety as follows:

          4.1  Books.

          Complete and accurate books of account shall be kept at the principal
     place of business of the Partnership and shall be open to inspection by any
     Partner or his or its authorized representative at any time during ordinary
     business hours. The Partnership books shall be kept on an accrual method of
     accounting as long as such method of accounting is in compliance with Code.

          4.2  Financial Statements.

          (a)  Within sixty (60) days after the end of each calendar year, the
     General Partner shall use its reasonable efforts to cause the Partnership
     to have prepared audited financial statements for the Partnership in
     accordance with generally accepted accounting principles.

          (b)  Within one hundred twenty (120) days after the end of each
     calendar year, the General Partner shall use its best efforts to have the
     Partnership caused to be prepared and mailed to each Partner a report for
     such year including:

               (i)  A statement setting forth the assets and liabilities of the
          Partnership as of the beginning and the end of such calendar year;

               (ii) Each Partner's Capital Account as of such dates;

                                       10
<PAGE>

               (iii) A statement of operations, setting forth each allocable
          item of income and loss; and

               (iv)  Any other information, including appropriate tax reporting
          information, which the General Partner shall deem necessary or
          appropriate.

          4.3  Distribution of Property.

          In the case of a distribution of property by the Partnership, which is
     made in the manner provided in Section 734 of the Code or in the case of a
     transfer of a Partnership interest, as permitted by this Agreement, which
     is made in the manner provided in Section 743 of the Code, the General
     Partner may, in its discretion, file an election under Section 754 of the
     Code in accordance with the procedures set forth in the then applicable
     Treasury Regulations. If such an election is filed, neither the Partnership
     nor the General Partner shall be required to provide the Partners with any
     extraordinary accounting or tax information (other than as required by the
     Code or the Treasury Regulations thereunder) with respect to the resulting
     adjustments to Partnership basis.

5.   Article V Amendments.  Article V of the Original Partnership Agreement is
     --------------------
hereby deleted in its entirety and replaced with the following Article V which
shall read in its entirety as follows:

                                       V

                             PERCENTAGE INTERESTS,

                  CAPITAL ACCOUNTS AND CAPITAL CONTRIBUTIONS

          5.1  Percentage Interests in Partnership.

          Subject to Section 5.7, the Partners' respective interests in the
     Partnership's profits and losses ("Percentage Interests") are as follows:
                                        --------------------

              Name of Partner                         Percentage Interest
              ---------------                         -------------------

              Argosy Energy, Inc.                     44.6404%

              Neo Energy, Inc.                        49.9054%

              Garnet Resources Corp.                  5.0738%

              Dale E. Armstrong                       0.2901%

              Richard Shane McKnight                  0.0903%

          The Partners hereby acknowledge and agree that the Percentage Interest
     set forth above opposite the name of a Partner under the column entitled
     "Percentage Interest"

                                       11
<PAGE>

     represents his or its sole interest in the profits or losses to be derived
     from the Partnership Property or any assets acquired by the Partnership.

          5.2  Capital Accounts.

               The Partners have heretofore made capital contributions to the
     Partnership ("Capital Contributions") and/or have acquired interests in the
                   ---------------------
     Partnership so that each Partner has a capital account ("Capital Account").
                                                              ---------------
     The Partners hereby agree that if the underlying Capital Account of each
     Partner as of December 31, 1999, when compared to the Capital Accounts of
     all Partners ("Capital Account Percentage"), is not in the same ratio as
                    --------------------------
     such Partner's Percentage Interest, the Capital Accounts of all Partners
     shall be restated as of January 1, 2000, to make such Capital Account
     Percentage of each Partner equal to its Percentage Interest. After such
     capital shift by the Partners, if any, the underlying negative Capital
     Accounts of the Partners as of January 1, 2000, shall be as follows:

            Argosy Energy, Inc.                   $(1,789,312)

            Neo Energy, Inc.                      $(2,000,349)

            Garnet Resources Corp.                $(  203,371)

            Dale E. Armstrong                     $(   11,629)

            Richard Shane McKnight                $(    3,620)

          A separate Capital Account will be maintained for each Partner in
     accordance with Code Section 704(b) and the Treasury Regulations
     thereunder, including without limitation, Treasury Regulation Section
     1.704-1(b)(2)(iv). The General Partner shall have the authority to
     determine all questions relating to the maintenance of Partners' Capital
     Accounts, and the General Partner may modify the manner in which the
     Capital Accounts are maintained under this Section 5.2 in order to comply
     with the provisions of Treasury Regulation Section 1.704-1(b) and any other
     applicable provisions of the Code or Treasury Regulations in order to cause
     Partner Capital Accounts to be maintained in compliance with the provisions
     of the Code and Treasury Regulations. The General Partner shall determine
     whether any elective adjustments to Capital Accounts permitted under
     Treasury Regulation Section 1.704-1(b)(2)(iv) shall be made.

          5.3  Return of Contributions.

          No Partner shall be entitled to withdraw or to demand a refund or
     return of any amount contributed to the Partnership as a Capital
     Contribution or as an Additional Capital Contribution, as hereinafter
     defined, nor to receive any interest thereon.

                                       12
<PAGE>

          5.4  Additional Capital Contributions.

          If the General Partner reasonably determines that the Dollar Revenues
     and Peso Revenues from the Partnership Property are insufficient to (i)
     meet current or anticipated expenses of the Partnership; (ii) enable the
     Partnership to comply with any applicable law, rule, regulation or
     contractual obligation; (iii) enable the Partnership to engage in the
     exploration, development or production of oil and gas from the Property;
     and/or (iv) maintain production levels consistent with prudent operating
     standards and sound engineering practices (the "Cash Needs"), the General
                                                     ----------
     Partner shall send a written request by telephone facsimile or by certified
     mail, return receipt requested, to each Partner requesting each Partner to
     contribute its pro rata share, based upon the relative Percentage Interests
     of the Partners, of the Cash Needs ("Additional Capital Contributions"),
                                          --------------------------------
     which request shall specify in reasonable detail the amount, purpose and
     justification for the proposed Additional Capital Contribution. Each
     Partner may, within thirty (30) days of such receipt, make its Additional
     Capital Contribution to the Partnership by wire transfer or cashier's check
     in an amount equal to that Partner's Percentage Interest of the total
     Additional Capital Contribution being requested by the General Partner. No
     Partner will have any personal liability pursuant hereto to contribute
     additional capital to the Partnership under this Section 5.4 at any time,
     and the remedies set forth in this Article V shall be the exclusive
     remedies of the Partnership for any Partner's failure to contribute
     additional capital to the Partnership. Each Partner acknowledges and agrees
     that although the Partner has no personal liability to contribute
     additional capital to the Partnership, the Partner's interest in the
     Partnership may be diluted and otherwise adversely affected pursuant to
     rights vested in the General Partner in this Article V as a consequence of
     such Partner's decision not to make any Additional Capital Contribution
     requested pursuant to this Section 5.4.

          5.5  Default on Additional Capital Contribution.

          If any Partner ("Defaulting Partner") fails to contribute his or its
                           ------------------
     share of a required Additional Capital Contribution within thirty (30) days
     of receipt of the written request for such contribution by the General
     Partner, the General Partner shall immediately send a notice (the "Notice")
                                                                        ------
     by telephonic facsimile, by certified mail, return receipt requested to the
     Defaulting Partner and to the remaining Partners who have been given a
     request for payment pursuant to Section 5.4 and have made such Additional
     Capital Contributions ("Non-Defaulting Partners"). The Notice shall specify
                             -----------------------
     the amount in default and shall specify that such amount must be paid by
     the Defaulting Partner by the close of business on the tenth (10th)
     calendar day after the date of the Notice (the "Cure Date"). If the
                                                     ---------
     Defaulting Partner fails to make any portion of the Additional Capital
     Contribution requested of the Limited Partner pursuant to Section 5.4 by
     the Cure Date, the General Partner after accepting the other Partners'
     Additional Capital Contributions may exercise any or all of the following
     remedies, but no others, on behalf of the Partnership:

               (a)  Setoff.  Setoff the amount of the requested and unmade
                    ------
          Additional Capital Contribution against any amounts which would
          otherwise be payable by the Partnership to the Defaulting Partner;

                                       13
<PAGE>

               (b)  Adjust Percentage Interests. Readjust the Percentage
                    ---------------------------
          Interests of the Partners as provided in Section 5.7; provided,
          however, this remedy shall only be available to the extent the Non-
          Defaulting Partners contribute the Additional Capital Contribution
          requested of the Defaulting Partner; or

               (c)  Default Loan. Offer the other Partners the opportunity to
                    ------------
          make a Default Loan on the terms provided under Section 5.8 equal to
          the amount of the additional capital requested of the Defaulting
          Partner.

          5.6. Borrow Funds.

          In addition to or in lieu of requesting Additional Capital
     Contributions from the Partners pursuant to Section 5.4, the General
     Partner, on behalf of the Partnership, shall have the right to borrow funds
     from third parties on such terms and conditions, including rate of interest
     and maturity, as the General Partner deems advisable; provided, however,
     that in lieu of borrowing from third parties, any one or more of the
     Partners may, if acceptable to the General Partner, from time to time make
     advances to the Partnership to meet such requirements. Any such advance
     made by a Partner to the Partnership shall not be considered a Capital
     Contribution, but shall constitute a debt of the Partnership to the
     advancing Partner, payable at such time and on such terms as the General
     Partner and advancing Partner shall agree; provided, however that if the
     advancing Partner is the General Partner (or a Partner that controls, is
     controlled by, or under common control with the General Partner), the debt
     shall be payable on the later of (a) six (6) months from the advance or (b)
     within thirty (30) days following written demand and bear interest on the
     unpaid principal balance thereof until paid beginning on the date of such
     advance at a rate equal to the Stated Rate. Payments made to an advancing
     Partner will be credited first to interest and then to principal. At the
     request of the Partner making the advance, the Partnership will execute a
     promissory note evidencing this debt.

          5.7  Percentage Interest Adjustment.

          If the General Partner elects to adjust the Percentage Interests as
     provided in Section 5.5(c), the Percentage Interest of each Partner will be
     adjusted so that the Percentage Interest of each Partner will be equal to a
     fraction, the numerator of which will be equal to the aggregate Capital
     Contributions made by the Partner to date (including the contribution made
     under Section 5.4 and 5.5), and the denominator of which will be equal to
     the aggregate Capital Contributions made by all Partners to date (including
     the contributions made under Section 5.4 and 5.5). For purposes of the
     foregoing only, each Partner's aggregate Capital Contribution as of May 31,
     2000, shall be deemed to equal the following amount:

                                       14
<PAGE>

            Argosy Energy, Inc.                 $ 4,464,040

            Neo Energy, Inc.                    $ 4,990,540

            Garnet Resources Corp.              $   507,380

            Dale E. Armstrong                   $    29,010

            Richard Shane McKnight              $     9,030

          The Partners intend that the foregoing aggregate Capital Contribution
          amounts as of May 31, 2000, shall be used solely for the purposes set
          forth in this Section 5.6, and shall not be used for any other
          purposes whatsoever. Any adjustments to Percentage Interests
          calculated under this Section 5.6 shall be retroactively applied to
          the date the amount requested under Section 5.4 was due. The General
          Partner will promptly give each Limited Partner written notice of its
          Percentage Interest, as adjusted, each time an adjustment occurs. In
          no event, however, will the Percentage Interest of a Defaulting
          Partner be increased under this Section 5.7.

               5.8  Default Loan.

               (a)  The Partners, other than the Defaulting Partner, will have
          the option, but not the obligation, to accept an offer made by the
          General Partner under Section 5.4(d) to advance to the Partnership an
          amount of money equal to the amount requested of the Defaulting
          Partner under Section 5.4, which advance will be deemed to be a
          Capital Contribution by the Defaulting Partner and will be considered
          a loan (a "Default Loan") from the Partner or Partners making the
                     ------------
          advance (the "Lending Partners") to the Defaulting Partner, payable
                        ----------------
          upon demand and bearing interest at the lesser of the maximum rate
          permitted by applicable law or the rate of 18% per annum. If the
          Lending Partners make a Default Loan, upon written request by the
          Lending Partners, the Defaulting Partner will execute and deliver a
          promissory note payable to the Lending Partners as evidence of that
          Default Loan; provided that the failure by the Defaulting Partner to
          execute such a promissory note will not affect the validity of the
          Default Loan in question or the obligation of the Defaulting Partner
          to repay the Default Loan in accordance with the terms of this
          Agreement. If the Defaulting Partner fails upon demand to repay with
          interest any Default Loan made by the Lending Partners, the Partners
          will have the right to enforce the security interest granted to the
          Partners in Section 5.8(b).

               (b)  Each of the Partners hereby grants to each of the other
          Partners a security interest in the Partner's interest in the
          Partnership to secure the Partner's obligation to repay upon demand
          any Default Loan made to the Partner by the Lending Partners under
          Section 5.8(a); provided, however, the only right granted by such
          security interest is that while a Default Loan is outstanding, all
          amounts otherwise distributable to the Defaulting Partner by the
          Partnership under Article VIII or Article XII shall be paid by the

                                       15
<PAGE>

     Partnership on behalf of the Defaulting Partner to the Lending Partners in
     respect of accrued interest on and unpaid principal of any outstanding
     Default Loans made by the Lending Partners (such payments to be applied
     first to accrued but unpaid interest on and then to outstanding principal
     of such Default Loans). At such time as the Defaulting Partner's
     obligations to the Lending Partners under any Default Loan hereby secured
     are paid in full, distributions to the Defaulting Partner will resume as
     set forth in this Agreement. Any amounts paid on behalf of a Defaulting
     Partner will be deemed to have first been distributed or paid to the
     Defaulting Partner and then paid to the Lending Partners. Each Partner,
     upon failure to make an Additional Capital Contribution requested under
     Section 5.4, hereby irrevocably appoints the Partnership and the other
     Partners, and the agents, officers or employees of the Partnership and the
     other Partners, its attorneys-in-fact, coupled with an interest, with full
     power to prepare and execute any documents, instruments and agreements,
     including but not limited to the note permitted under 5.8(a) evidencing a
     Default Loan, if any, and such financing statements, continuation
     statements and other instruments and documents as may be appropriate to
     perfect, continue and enforce that security interest in favor of the other
     Partners.

          5.9  Deficit Capital Accounts.

          No Partner will be required to pay to the Partnership, to any other
     Partner or to any third party any deficit balance which may exist from time
     to time in the Partner's Capital Account.

6.   Article VI Amendments.  Article VI of the Original Partnership Agreement is
     ---------------------
hereby deleted in its entirety and replaced with the following Article VI which
shall read in its entirety as follows:

                                      VI

                              COSTS AND EXPENSES

          All costs and expenses of the Partnership shall be paid from
     Partnership funds and charged to the respective Partnership accounts. Such
     costs and expenses which are incurred in Colombia, other than those
     specified in subparagraph (a) below, shall be paid to the fullest extent
     possible out of Pesos Revenues. Such costs and expenses shall include but
     not be limited to:

          (a)  All payments required to be made under any services agreement;

          (b)  Legal, accounting (including the costs of any audited financial
     statements), surveying, consulting, engineering and operating expenses;

          (c)  Taxes (except income taxes payable by the Partners), insurance
     premiums and interest;

          (d)  Expenditures, if any, required for plugging and abandonment
     and/or other environmental clean-up costs ("Putumayo Costs") associated
                                                 --------------
     with the Aporte Putumayo

                                       16
<PAGE>

          concession, which the Partnership has relinquished to the Colombian
          Government but pursuant to which the Partnership is still potentially
          liable for Putumayo Costs, if any;

               (e)  Costs and expenses of bookkeeping, accounting and reporting
          services for the Partnership;

               (f)  General Partner's reimbursable expenses called for by
          Section 2.3 hereof;

               (g)  Every other cost and expense properly incurred in the
          Partnership business, whether like or unlike the foregoing.

7.        Article VII Amendments. Article VII of the Original Partnership
          ----------------------
Agreement is hereby deleted in its entirety and replaced with the following
Article VII which shall read in its entirety as follows:

                                     VII.

                              PROFITS AND LOSSES

               Section 7.1  Allocations of Profits and Losses.

               After giving effect to the special allocations set forth in
          Section 7.2, for any taxable year of the Partnership ending on or
          after the date of this Amendment, all Net Profits or Net Losses for
          such year will be allocated to the Partners as follows:

               (a)  Net Profits.
                    -----------

                    Net Profits shall be allocated to the Partners in proportion
               to their respective Percentage Interests in the Partnership.

               (b)  Net Loss.
                    --------

                    Net Loss shall be allocated to the Partners in proportion to
               their respective Percentage Interests in the Partnership.

               Section 7.2  Special Allocations.

               (a)  The following special allocations shall, except as otherwise
          provided, be made in the following order:

                    (i)   Minimum Gain Chargeback. Notwithstanding any other
                          -----------------------
               provision of this Agreement, if there is a net decrease in
               Partnership Minimum Gain or in any Partner Minimum Gain during
               any taxable year or other period, prior to any other allocation
               pursuant hereto, the Partners shall be specially allocated items
               of Profit for such year (and, if necessary, subsequent years) in
               an amount and manner required by Treasury Regulation Section
               1.704-2(f) or 1.704-2(i)(4). The items to be so allocated shall
               be determined in accordance with Treasury Regulation Section
               1.704-2. This Section 7.2(a)(i) is intended to comply with the

                                       17
<PAGE>

               minimum gain chargeback requirements of Treasury Regulation
               Section 1.704-2(f) or 1.704-2(i)(4), will be interpreted
               consistently with the Treasury Regulations and will be subject to
               all exceptions provided therein.

                    (ii)  Qualified Income Offset. Any Partner who unexpectedly
                          -----------------------
               receives an adjustment, allocation or distribution described in
               Treasury Regulation Section 1.704-1(b)(2)(ii)(d)(4), (5) or (6)
               which causes or increases an Adjusted Capital Account Deficit
               shall be allocated items of income or gain in an amount and
               manner sufficient to eliminate, to the extent required by such
               Treasury Regulation, the Adjusted Capital Account Deficit of the
               Partner as quickly as possible. This Section 7.2(a)(ii) is
               intended to constitute a "qualified income offset" within the
               meaning of Treasury Regulation Section 1.704-1(b)(2)(ii)(d), will
               be interpreted consistently with the Treasury Regulations and
               will be subject to all exceptions provided therein.

                    (iii) Gross Income Allocation. Each Partner who has a
                          -----------------------
               deficit Capital Account at the end of any Partnership taxable
               year that is in excess of the amount the Partner is obligated to
               restore pursuant to any provision of this Agreement, including
               any amount that it is deemed to be obligated to restore under
               Treasury Regulation Section 1.704-2(g)(1) and Section 1.704-
               2(i)(5), will be specially allocated items of Partnership income
               and gain in the amount of the excess as quickly as possible.

                    (iv)  Nonrecourse Deductions. Nonrecourse Deductions for any
                          ----------------------
               taxable year or other period will be specially allocated among
               the Partners pro rata in proportion to their respective
               Percentage Interests in the Partnership.

                    (v)   Partner Nonrecourse Deductions. Any Partner
                          ------------------------------
               Nonrecourse Deductions for any taxable year or other period will
               be allocated to the Partner who bears the economic risk of loss
               with respect to the Partner Nonrecourse Debt to which such
               Partner Nonrecourse Deductions are attributable in accordance
               with principles under Treasury Regulation Section 1.704-2(i).

                    (vi)  Code Section 754 Adjustments. To the extent an
                          ----------------------------
               adjustment to the adjusted tax basis of any Partnership asset
               under Sections 734(b) or 743(b) of the Code is required to be
               taken into account in determining Capital Accounts under Treasury
               Regulation Section 1.704-1(b)(2)(iv)(m), the amount of the
               adjustment to the Capital Accounts will be treated as an item of
               gain (if the adjustment increases the basis of the asset) or loss
               (if the adjustment decreases the basis), and the gain or loss
               will be specially allocated to the Partners in a manner
               consistent with the manner in which their Capital Accounts are
               required to be adjusted under Treasury Regulation Section 1.704-
               1(b)(2)(iv)(m).

               (b)  Curative Allocations. The "Regulatory Allocations" consist
                    --------------------
          of allocations made to a Partner (or predecessor) under Section
          7.2(a). Notwithstanding any other provision of this Article VII, other
          items of income, gain, loss and deduction will be allocated among the
          Partners so that, to the extent possible, the net amount of those

                                       18
<PAGE>

          allocations of other items and the Regulatory Allocations to each
          Partner will be equal to the net amount that would have been allocated
          to the Partner if the Regulatory Allocations had not occurred. The
          Partner shall take into account future Regulatory Allocations under
          Section 9.3(a)(i) that, although not yet made, are likely to offset
          Regulatory Allocations under Sections 9.3(a)(iv) and 9.3(a)(v).

               7.3  Compliance with Section 704(c).

               In accordance with Section 704(c) of the Code and the applicable
          Treasury Regulations thereunder, income, gain, loss and deduction with
          respect to any Partnership property for which its adjusted tax basis
          differs from its Book Basis will, solely for tax purposes, be
          allocated among the Partners so as to take account of any variation
          between the adjusted tax basis of such property to the Partnership for
          federal income tax purposes and the Book Basis of such Property. Any
          elections or other decisions relating to allocations under this
          Section 7.3 will be made in any manner which the General Partner shall
          determine is consistent with Section 704(c) of the Code and the
          Treasury Regulations promulgated thereunder and reasonably reflects
          the purpose and intention of this Agreement. Allocations under this
          Section 7.3 are solely for purposes of federal, state and local taxes
          and will not affect, or in any way be taken into account in computing,
          any Partner's Capital Account or share of Profits, Losses or other
          items or distributions under any provision of this Agreement.

               7.4  Intent of Allocations.

               The parties intend that the foregoing allocation provisions of
          this Article VII shall produce final Capital Account balances of the
          Partners that will equal their Percentage Interests such that the
          liquidating distributions to each Partner under Section 12.2 will
          equal their final positive Capital Account balance. To the extent that
          the allocation provisions of this Article VII would fail to produce
          such final Capital Account balances, (a) such provisions shall be
          amended by the General Partner if and to the extent necessary to
          produce such result, and (b) Net Profits and Net Losses of the
          Partnership for prior open years (or items of gross income, gain, loss
          and deduction of the Partnership for such years) shall be reallocated
          by the General Partner among the Partners to the extent it is not
          possible to achieve such result with allocations of items of income
          (including gross income and gain), deduction and loss for the current
          year and future years. This Section 7.4 shall control notwithstanding
          any other provision of this Agreement or the reallocation or
          adjustment of taxable income, taxable loss or items thereof by the
          Internal Revenue Service or any other taxing authority.

               7.5  Partner Acknowledgment.

                    The Partners agree to be bound by the provisions of this
          Article VII in reporting their shares of Partnership income and loss
          for income tax purposes.

                                       19
<PAGE>

8.   Article VIII Amendments. Article VIII of the Original Partnership Agreement
     -------------------------
is hereby deleted in its entirety and replaced with the following Article VIII
which shall read in its entirety as follows:

                                     VIII

                                 DISTRIBUTIONS

          Subject to Section 5.8, paying or making provision for the payment,
     when due, of obligations of the Partnership and establishing and
     maintaining such reserves as the General Partner reasonably determines may
     be required for the proper operation of the Partnership's business after
     taking into consideration Pesos Revenues that are or will be available to
     pay anticipated costs and obligations of the Partnership, the Partnership
     promptly on, or as soon as possible after the last day of each calendar
     month shall distribute to the Partners, pro rata in proportion to their
     respective Percentage Interests, any remaining Dollar Revenues then being
     held by the Partnership. Notwithstanding any other provision of this
     Agreement, no distributions of Peso Revenues will be made to a Partner
     under the provisions of this Article VIII. Each Partner consents to the
     distributions provided for in this Article VIII and understands that
     because of differences between income and cash flow, distributions to a
     Partner may constitute a return of capital or may be less than a Partner's
     distributive share of Partnership income.

9.   Article IX Amendments. Article IX of the Original Partnership Agreement is
     ---------------------
hereby deleted in its entirety and replaced with the following Article IX which
shall read in its entirety as follows:

                                      IX

                       TRANSFER OF PARTNERSHIP INTEREST

          9.1  Transferee of General Partner.

          The General Partner may transfer all or any part of its Partnership
     interest without the written consent of the Limited Partners; provided,
     however, the transferee of all or part of the General Partner's interest
     shall not, except with the consent of Limited Partners holding not less
     than eighty percent (80%) of the Percentage Interests (after excluding the
     General Partners Interest), be entitled during the continuance of the
     Partnership to become a general partner in the Partnership or interfere in
     the management or administration of the Partnership business. Except with
     such consent, the transferee shall merely be entitled to become a limited
     partner in the Partnership, to receive, in accordance with the terms of the
     transfer, the profits or other compensation by way of income, or the return
     of the capital contribution to which the transferor General Partner
     otherwise would have been entitled and shall be bound by all terms and
     conditions of this Agreement, including without limitation, the obligation
     to make all Additional Capital Contributions in accordance with Section 5.4
     hereof. Neither the provisions of this Article IX, nor the failure of the
     other Partners to purchase the interest of the General Partner, shall be
     construed as an acceptance by the Partners of any third party as a Partner.

                                       20
<PAGE>

          9.2  Substitute Limited Partner.

          (a)  A Limited Partner may transfer all or less than all of its
     Partnership interests without the consent of any Partner; provided,
     however, notwithstanding anything in this Agreement to the contrary, no
     assignee of a Limited Partner's interest in the Partnership shall have the
     right to become a substitute Limited Partner (an assignee who is admitted
     by the Partnership to all of the rights of a Limited Partner) in place of
     his assignor unless:

               (i)    The fully executed acknowledged written instrument of
          assignment which has been filed with the Partnership sets forth the
          intention of the assignor that the assignee became a substitute
          Limited Partner in his place;

               (ii)  The assignor and assignee execute and acknowledge such
          other instruments as the General Partner may deem necessary or
          desirable to effect such admission, including the written acceptance
          and adoption by the assignee of the provisions of this Agreement and
          his execution, acknowledgment, and delivery to the General Partner of
          a Power-of -Attorney, the form and content of which are more fully
          described in Article XI;

               (iii) The written consent of the General Partner to such
          substitution is obtained, the granting of which shall be in the sole
          and absolute discretion of the General Partner;

               (iv)  The assignee shall have agreed to acquire the interest in
          the Partnership for his own account, for investment, and not in
          connection with distribution or resale;

               (v)   The assignor delivers to the General Partner an opinion of
          counsel, acceptable in form and content to counsel for the General
          Partner, stating that the proposed transfer of the assignor's interest
          in the Partnership will not violate any applicable federal or state
          laws or regulations;

               (vi)  An amended Certificate of Limited Partnership is recorded,
          in accordance with the laws of the State of Utah, listing the assignee
          as a Limited Partner; and

               (vii) The assignor and assignee pay such reasonable expenses as
          are charged by the Partnership to accomplish the transfer of the
          interests in the Partnership.

          (b)  The failure or refusal by the General Partner to consent to an
     assignee becoming a substitute Limited Partner shall not affect the
     validity and effectiveness of any instrument, which assigns the right to
     receive the share of the profits or other compensation by way of income, or
     the return of the Capital Contribution of the assignor, provided such
     instrument is in form satisfactory to the General Partner and a duly
     acknowledged counterpart is filed with the Partnership. No consent or
     approval of any of the Limited Partners shall be required for the admission
     of a substitute Limited Partner.

                                       21
<PAGE>

     Except for the conditions set forth in Section 9.2(a)(ii), the conditions
     set forth in Section 9.2(a), shall be inapplicable to a person seeking to
     become a substitute Limited Partner when such person has received his
     interest in the Partnership as the result of a foreclosure proceeding or
     the death of a Limited Partner.

          9.3  Substitution of Assignee Failing to Satisfy Conditions.

          The General Partner may waive any or all requirements of this Article
     IX, and admit an assignee to the Partnership as a substitute Limited
     Partner, if it finds, in its sole discretion, that such action is in the
     best interest of the Partnership.

10.  Article X Amendments. Article X of the Original Partnership Agreement is
     --------------------
hereby deleted in its entirety and replaced with the following Article X which
shall read in its entirety as follows:

                                       X

                       ADMISSION OF ADDITIONAL PARTNERS

          Additional Limited Partners may be admitted to the Partnership by the
     General Partner with the consent of Limited Partners holding eighty percent
     (80%) of the Percentage Interests held by all Limited Partners; provided,
     however, the foregoing shall not apply to additional Limited Partners
     admitted through the issuance of additional Partnership interests in
     compliance with Section 2.2(b)(v). Additional General Partners shall not be
     admitted to the Partnership except with the consent of Limited Partners
     holding eighty percent (80%) of the Percentage Interests held by all
     Limited Partners.

11.  Article XI Amendments. Article XI of the Original Partnership Agreement is
     ----------------------
hereby amended by deleting the words "Upon becoming a party to this Agreement,
each" from the first sentence of Section 11.1 and inserting in their place the
following: "Each". Article XI is further amended by deleting the word
"substituted" from the eleventh line of Section 11.2 and inserting in its place
the word "substitute".

12.  Article XII Amendments. Article XII of the Original Partnership Agreement
     ----------------------
is hereby deleted in its entirety and replaced with the following Article XII
which shall read in its entirety as follows:

                                      XII

                DISSOLUTION AND TERMINATION OF THE PARTNERSHIP

          12.1 Events Causing Dissolution.

          The Partnership shall be dissolved and terminated and its assets
     distributed pursuant to the provisions of Section 12.2 hereof and
     applicable law upon the first of the following event to occur:

          (a)  December 31, 2025;

                                       22
<PAGE>

          (b)  The bankruptcy of the Partnership, which shall be the date when
     the Partnership obtains an order for relief under Title 11, United States
     Code, or an order or decree determining insolvency under any applicable
     state insolvency law;

          (c)  The sale or loss of the Property and the distribution of all
     proceeds of such sale in accordance with this Agreement;

          (d)  The decision of Partners holding 80% or more of the Percentage
     Interests as set forth in Section 5.1; or,

          (e)  The dissolution, bankruptcy, withdrawal or insolvency of the
     General Partner, unless, within the ninety (90) day period immediately
     following such event, a majority in interest of the remaining Partners
     elect to continue the Partnership and elect one or more new general
     partners. The Partnership shall not be dissolved or terminated by reason of
     the death, legal incompetency, insolvency, bankruptcy, dissolution or other
     termination of any Limited Partner.

          12.2 Termination.

          On dissolution of the Partnership, either by expiration of the term of
     the Partnership or otherwise as set forth herein, the Partnership shall
     immediately commence to liquidate its properties and wind up its affairs.
     The Partners, or their representatives, shall continue to share profits and
     loses during the winding up period in the same manner as before the
     election to terminate. The liquidation proceeds of the Partnership shall be
     applied and distributed in the following order:

          (a)  To the payment and discharge of all of the Partnership's debts
     and liabilities to persons other than Partners;

          (b)  To the payment and discharge of all of the loans and advances
     made by Partners to the Partnership;

          (c)  To the setting up of any reasonable reserves for contingent or
     unforeseen liabilities or obligations of the Partnership;

          (d)  The balance, if any, shall be allocated to the Partners in
     accordance with their respective Percentage Interests.

          12.3 Distribution in-Kind.

          If the General Partner or other person acting as liquidator determines
     that a portion of the Partnership's assets should be distributed in-kind to
     the Partners, it shall obtain an independent appraisal of the fair market
     value of each such asset as of a date reasonably close to the date of
     liquidation. Any unrealized appreciation or depreciation with respect to
     any asset to be distributed in-kind shall be allocated among the Partners
     (in accordance with the provisions of Article VII and assuming that the
     assets were sold for the appraised value), and taken into consideration in
     determining the balance in the Partners' Capital Accounts as of the date of
     final liquidation. Distribution of any such

                                       23
<PAGE>

     asset in-kind to a Partner shall be considered a distribution of an amount
     equal to the asset's fair market value for purposes of Section 12.2.

13.  Additional Amendments. Articles XIII, XIV, XV, XVI, and XVII of the
     ---------------------
Original Partnership Agreement are hereby deleted in their entirety and replaced
with the following new Articles XIII, XIV, XV, XVI, and XVII, which shall read
each in its entirety as follows:

                                     XIII

               AMENDMENTS; ARBITRATION; INSURANCE; MISCELLANEOUS

          13.1 Material Amendments.

          Unless otherwise provided in Section 13.2, material amendments to this
     Agreement must be approved by the written consent of Partners holding at
     least eighty percent (80%) or more of the Percentage Interests.
     Notwithstanding the foregoing, no amendment shall change the Partnership to
     a general partnership, change the limited liability of Limited Partners, or
     change the liability of the General Partner, unless such amendment or
     amendments are approved by the written consent of all Partners affected by
     the amendment. All sections or provisions of the Agreement terminated
     pursuant to an amendment hereunder shall be deleted from this Agreement.

          13.2 Other Amendments.

          Amendments to this Agreement which, in the opinion of the General
     Partner with the advice of counsel, are (i) of an inconsequential nature
     and do not affect the rights of the Partners in any material respect, or
     are (ii) required or contemplated by this Agreement, or are (iii) necessary
     to prevent the Partnership from being classified as an association taxable
     as a corporation under the Code, may be made by the General Partner by
     giving written notice thereof to the Partners, stating the terms and
     effective date of such amendment. As an example of an immaterial amendment
     permitted under this Section 13.2, the General Partner may change the name
     of the Partnership to avoid a conflict or more accurately to depict the
     properties owned by the Partnership.

                                      XIV

                                  ARBITRATION

          If any controversy or claim arising out of this Agreement cannot be
     settled by the Partners, the controversy or claim shall be settled by
     arbitration in Dallas, Dallas County, Texas in accordance with the rules of
     the American Arbitration Association then in effect, and judgment on the
     award may be entered in any court having jurisdiction.

                                       24
<PAGE>

                                      XV

                                   INSURANCE

          The Partnership shall purchase from others, at the expense of the
     Partnership, such contracts of liability, casualty and other insurance
     which the General Partner deems advisable, appropriate or convenient for
     the protection of the assets or affairs of the Partnership and Partners or
     for any purpose convenient or beneficial to the Partnership. Such insurance
     shall be purchased in an amount determined by the General Partner.

                                      XVI

                   ACTIONS IN VIOLATION OF UNITED STATES LAW

          No Partner shall do or cause to be done, on behalf of the Partnership
     or in connection with the Property, any act which violates the Foreign
     Corrupt Practices Act or the International Boycott Laws of the United
     States. Any Partner who violates the provisions of this Article XVI hereby
     agrees to indemnify and hold harmless the Partnership and the other
     Partners from and against any and all liabilities which shall arise by
     reason of said Partner's actions.

                                     XVII

                                 MISCELLANEOUS

          17.1 Notices.

          Any notice, election or other communication provided for or required
     by this Agreement shall be in writing and shall be deemed to have been
     given when transmitted by facsimile, when delivered personally or when
     deposited in the United States Mail, certified mail, return receipt
     requested, postage prepaid, and addressed to the Partner to whom such
     notice is intended to be given at such Partner's address as it appears on
     Exhibit B hereto or on the records of the Partnership. A Partner may change
     the address for the giving of notices by sending a written notice to the
     General Partner in accordance with the provision of this Section 17.1.

          17.2 Binding Effect.

          This Agreement shall inure to the benefit of and shall be binding upon
     the Partners, their legal representatives, heirs, administrators,
     successors and assigns.

          17.3 Counterpart Originals.

          For the convenience of the Partners, any number of counterpart
     originals hereof may be executed, all of which taken together shall
     constitute one Agreement.

                                       25
<PAGE>

          17.4  Article and Sections Headings.

          The title of the Articles and Sections herein have been inserted as a
     matter of convenient reference only and shall not control or affect the
     meaning or construction of any of the terms or provisions hereof

          17.5  References to Internal Revenue Code.

          All references herein to provisions of the Internal Revenue Code shall
     be deemed also to refer to any amendments or successor provisions hereafter
     enacted.

          17.6  Governing Law.

          This Agreement is entered into under and shall be governed by the laws
     of the State of Utah. However, in the event of inconsistency between the
     provision of this Agreement and those of the Utah Limited Partnership Act,
     the provisions of this Agreement shall be controlling.

          17.7  Further Action.

          The Partners hereby covenant and agree that they will execute such
     additional instruments and documents and take such other and further action
     as is or may become necessary or convenient, in the sole judgment of the
     General Partner, to effectuate and carry out the terms and conditions of
     this Agreement.

          17.8  Severability.

          In the event any one or more of the provisions contained in this
     Agreement shall be held to be invalid, illegal or unenforceable in any
     respect, such invalidity, illegality or unenforceability shall not affect
     the validity of any other provision hereof and this Agreement shall be
     construed as if such invalid, illegal or unenforceable provision had never
     been contained herein, provided that the basic intent of this Agreement is
     not thereby impaired.

          17.9  Construction.

          As used herein, all words in any gender shall be deemed to include the
     masculine, feminine, or neuter gender, all singular words shall include the
     plural, and all plural words shall include the singular. The term "person"
     shall include an individual, corporation, partnership, trust, estate or any
     other entity.

          17.10 Enforcement.

          In the event of any breach of this Agreement, the party in default
     hereunder shall bear the costs of enforcing this Agreement, including
     reasonable attorneys' fees whether incurred with or without suit, or with
     or without arbitration.

                                       26
<PAGE>

          17.11 Entire Agreement; Prior Agreements Superseded.

          This Agreement constitutes the entire agreement among the Partners
     pertaining to the subject matter contained herein. This Agreement
     supersedes any and all prior contemporaneous agreements, letters of intent,
     representations and understandings between or among the Partners, whether
     written or verbal, respecting the within subject matter.

          17.12 Waiver of Right to Decree of Dissolution.

          The parties hereby agree that irreparable damage would be done to the
     goodwill and reputation of the Partnership if any Partner should bring an
     action in court to dissolve the Partnership. Each party hereby waivers and
     renounces his right to such a court decree of dissolution or to seek the
     appointment by the court of a liquidator for the Partnership.

14.  Effect of Amendment.  Except as expressly amended herein, the provisions of
     -------------------
the Original Partnership Agreement shall remain in full force and effect.

15.  Successors and Assigns. This Amendment shall be binding upon, and shall
     ----------------------
inure to the benefit of the parties hereto and their respective heirs, legal
representatives, successors and assigns.

16   Modification and Waiver. No supplement, modification, waiver or termination
     -----------------------
of this Amendment or any provisions hereof shall be binding unless executed in
writing by the requisite number of Partners required to amend the Partnership
Agreement. No waiver of any of the provisions of this Amendment shall constitute
a waiver of any other provision (whether or not similar), nor shall such waiver
constitute a continuing waiver unless otherwise expressly provided.

17.  Severability. In the event any one or more provisions contained in this
     ------------
Amendment shall be held to be invalid, illegal or unenforceable in any respect,
such invalidity, illegality or unenforceability shall not affect the validity of
any other provision hereof and this Amendment shall be construed as if such
invalid, illegal or unenforceable provision had never been contained herein,
provided that the basic intent of this Amendment is not thereby impaired.

18.  Counterparts. This Amendment may be executed, including by facsimile
     ------------
transmission, in one or more counterparts, all of which together shall
constitute one and the same Amendment.

                          [Signature Page to Follow]

                                       27
<PAGE>

     IN WITNESS WHEREOF, the parties have hereunto set their hands as of the day
and year first above written.


                                        GENERAL PARTNER:
                                        ARGOSY ENERGY, INC.

                                        By /s/ R. Suttill
                                           --------------
                                        Its President
                                            -------------


                                        LIMITED PARTNERS:
                                        NEO ENERGY, INC.

                                        By /s/ R. Suttill
                                           --------------
                                        Its President
                                            -------------


                                        GARNET RESOURCES, CORP.

                                        By /s/ R. Suttill
                                          ---------------
                                        Its President
                                            -------------

                                       28