EXHIBIT 10.5

                                                                  Execution copy

                             CONTRIBUTION AGREEMENT

                       EnerVest Management Partners, Ltd.

                           EnerVest Operating, L.L.C.

                             CGAS Exploration, Inc.

                               EV Investors, L.P.

                                 EVCG GP, L.L.C.

                              CGAS Properties, L.P.

                                  EnCap Energy

                              Capital Fund V, L.P.

                          EnCap V-B Acquisitions, L.P.

                              EV Management, L.L.C.

                               EV Energy GP, L.P.

                            EV Energy Partners, L.P.

                               CGas Holdings, LLC

                               EVEC Holdings, LLC

                               September 29, 2006



                                Table of Contents


                                                                               Page
                                                                           -------------
                                                                        
ARTICLE I. Definitions                                                                2
     Section 1.1    Defined Terms......................................               2
     Section 1.2    Other Defined Terms................................               3
     Section 1.3    Construction.......................................               3
     Section 1.4    References.........................................               4

ARTICLE II. CONTRIBUTION BY OWNERS OF PROPERTIES LP....................               4
     Section 2.1    Capitalization of the General Partner..............               4
     Section 2.2    Capitalization of the Partnership..................               4

ARTICLE III. Representations and Warranties............................               5
     Section 3.1    Representations and Warranties of All Parties......               5
     Section 3.2    Representations of EVMP Regarding Properties LP,
                    Properties GP, Clinton and Clinton GP..............               6
     Section 3.3    Representations of EVMP Regarding Capitalization
                    and Ownership of Properties GP, Properties LP,
                    Clinton GP and Clinton LP..........................               7
     Section 3.4    Representations and Warranties of EVMP Regarding
                    Ownership and Transfer of Interests in Properties
                    GP and Properties LP...............................               8
     Section 3.5    Representations and Warranties of EVOC Regarding
                    Ownership and Transfer of Interests in
                    Properties LP......................................               9
     Section 3.6    Representation and Warranties of EnCap Funds
                    Regarding Ownership and Transfer of Interests
                    in Properties LP...................................               9
     Section 3.7    Representations and Warranties of CGAS Regarding
                    Ownership and Transfer of Interests in
                    Clinton LP.........................................               9
     Section 3.8    Representations and Warranties of Investors
                    Regarding Ownership and Transfer of Interests
                    in Properties LP...................................              10
     Section 3.9    Representations and Warranties of the General
                    Partner Regarding Interests Issued.................              10
     Section 3.10   Representations and Warranties of the Partnership
                    Regarding Common and Subordinated Units............              10
     Section 3.11   Representations and Warranties of EVMP, EVOC,
                    the EnCap Funds and CGAS regarding securities
                    laws...............................................              10

ARTICLE IV. COVENANTS..................................................              11
     Section 4.1    Consent to Admission as a Member or Partner........              11
     Section 4.2    Further Assurances.................................              11
     Section 4.3    Conveyance of the Clinton Properties...............              11


                                       i



                                                                        
ARTICLE V. THE CLOSING.................................................              11
     Section 5.1    The Closing........................................              11
     Section 5.2    Deliveries at Closing by Sole Member of
                    Properties GP, Limited Partners of Properties
                    LP and Properties GP  and CGAS.....................              11
     Section 5.3    Deliveries at Closing by General Partner...........              12
     Section 5.4    Deliveries at Closing by the Partnership...........              12

ARTICLE VI. MISCELLANEOUS..............................................              12
     Section 6.1    Headings...........................................              12
     Section 6.2    Notices............................................              13
     Section 6.3    Assignment.........................................              13
     Section 6.4    Entire Agreement...................................              13
     Section 6.5    Counterparts.......................................              13
     Section 6.6    Governing Law......................................              13
     Section 6.7    Severability.......................................              13
     Section 6.8    No Survival of Representations and Warranties
                    and Covenants......................................              13

PROPERTIES LP SUBSIDIARIES............................................     Schedule 3.2
RECORD OWNERS OF PROPERTIES LP........................................     Schedule 3.3
ENCAP OWNERSHIP PERCENTS..............................................     Schedule 3.6


                                       ii


                             CONTRIBUTION AGREEMENT

      This Contribution Agreement ("AGREEMENT"), dated as of September 29, 2006,
is entered into by and among EnerVest Management Partners, Ltd., a Texas limited
partnership ("EVMP"), EVEC Holdings, LLC, a Delaware limited liability Company
("EVH"), EnerVest Operating, L.L.C., a Delaware limited liability company
("EVOC"), CGAS Exploration, Inc., an Ohio corporation ("CGAS"), EV Investors,
L.P., a Delaware limited partnership ("INVESTORS"), EVCG GP, L.L.C., a Delaware
limited liability company ("CLINTON GP"), CGAS Properties, L.P., a Delaware
limited partnership ("CLINTON LP"), CGas Holdings, LLC, a Delaware limited
liability company ("CGH") EnCap Energy Capital Fund V, L.P., a Texas limited
partnership ("ENCAP FUND V"), EnCap V-B Acquisitions, L.P., a Texas limited
partnership ("ENCAP FUND V-B" and, together with EnCap Fund V, the "ENCAP
FUNDS"), EV Management, L.L.C., a Delaware limited liability company
("MANAGEMENT"), EV Energy GP, L.P., a Delaware limited partnership (the "GENERAL
PARTNER"), and EV Energy Partners, L.P., a Delaware limited partnership (the
"PARTNERSHIP").

      WHEREAS, EVMP previously formed Management and EVH as a wholly owned
subsidiaries;

      WHEREAS, EVMP, as limited partner, and Management, as general partner,
formed the General Partner as a Delaware limited partnership;

      WHEREAS, EVMP, as organizational limited partner, and the General Partner,
as general partner, formed the Partnership as a Delaware limited partnership;

      WHEREAS, EVMP formed EV Properties GP, L.L.C., as a wholly-owned Delaware
limited liability company ("PROPERTIES GP");

      WHEREAS, EVMP, EV Investors and the EnCap Funds, as limited partners, and
Properties GP, as general partner, formed EV Properties, L.P., as a Delaware
limited partnership ("PROPERTIES LP");

      WHEREAS, EVMP, EnCap Investments GP, L.L.C., a Delaware limited liability
company ("ENCAP"), and the Partnership have entered into the Investor's
Agreement, dated May 12, 2006 ("INVESTOR'S AGREEMENT"), pursuant to which EVMP,
EnCap and the Partnership agreed to take all steps necessary to cause the
transactions described in this Agreement to occur;

      WHEREAS, as contemplated by the Investor's Agreement, EVMP will contribute
its membership interest in Properties GP to the General Partner in exchange for
a limited partnership interest in the General Partner;

      WHEREAS, as contemplated by the Investor's Agreement, EVMP, and the EnCap
Funds will contribute a portion of their limited partner interests in Properties
LP to the General Partner in exchange for limited partnership interests in the
General Partner;

      WHEREAS, EV Investors will contribute $144,150 in cash to the General
Partner in exchange for limited partnership interests in the General Partner;

                                       1


      WHEREAS, as contemplated by the Investor's Agreement, the General Partner
will contribute the membership interest in Properties GP and the limited partner
interests in Properties LP to the Partnership to maintain its 2% general partner
interest;

      WHEREAS, as contemplated by the Investor's Agreement, EVMP, EVOC,
Investors and the EnCap Funds desire to contribute the remainder of their
limited partnership interests in Properties LP to the Partnership in exchange
for Common Units, Subordinated Units and cash;

      WHEREAS, as contemplated by the Investor's Agreement, Properties LP has
formed Clinton GP as a wholly owned Delaware limited liability company;

      WHEREAS, as contemplated by the Investor's Agreement, Clinton GP, as
general partner, and CGAS, as limited partner, have formed Clinton LP as a
Delaware limited partnership;

      WHEREAS, as contemplated by the Investor's Agreement, CGAS contributed the
Clinton Properties to Clinton LP in exchange for a limited partnership interest
in Clinton LP;

      WHEREAS, as contemplated by the Investor's Agreement, CGAS will contribute
the limited partnership interest in Clinton LP to the Partnership in exchange
for Common Units, Subordinated Units and cash;

      WHEREAS, CGAS formed CGH as a wholly owned subsidiary; and

      WHEREAS, EVMP and EVOC assigned their right to receive Subordinated Units
to EVH and CGAS assigned its right to receive Subordinated Units to CGH;

      NOW THEREFORE, for good and valuable consideration, the parties agree as
follows:

                                   ARTICLE I.
                                   Definitions

      SECTION 1.1.DEFINED TERMS. The following terms have the meanings set forth
below when used in this Agreement:

      "CLINTON CONVEYANCE" means the conveyance of even date between CGAS, as
grantor, and Clinton LP, as grantee.

      "CLINTON PROPERTIES" means those interests in oil and gas properties
described in Exhibit A to the Clinton Conveyance.

      "COMMON UNITS" has the meaning set forth in the MLP Partnership Agreement.

      "GOVERNMENTAL AUTHORITY" means the United States, any foreign country,
state, county, city or other incorporated or unincorporated political
subdivision, agency or instrumentality thereof.

                                       2


      "GP PARTNERSHIP AGREEMENT" means the amended and restated agreement of
limited partnership of the General Partner.

      "INCENTIVE DISTRIBUTION RIGHTS" has the meaning set forth in the MLP
Partnership Agreement.

      "MLP PARTNERSHIP AGREEMENT" means the amended and restated agreement of
the limited partnership of the Partnership.

      "PERSON" shall mean a corporation, an association, a partnership, an
organization, a business, an individual or a Governmental Authority.

      "SUBORDINATED UNITS" has the meaning set forth in the MLP Partnership
Agreement.

      SECTION 1.2.OTHER DEFINED TERMS. The following terms are defined in the
sections indicated:



Term                    Section
- ------------            ----------
                     
Closing                 5.1
Agreement               First Paragraph
CGAS                    First Paragraph
CGH                     First Paragraph
Claim                   Section 3.4
Clinton GP              First Paragraph
Clinton LP              First Paragraph
Closing                 Section 5.1
EnCap                   Recitals
EnCap Fund V            Recitals
EnCap Funds V-B         Recitals
EVH                     First Paragraph
EVMP                    First Paragraph
EVOC                    First Paragraph
Investors               First Paragraph
Investor's Agreement    Recitals
General Partner         First Paragraph
Management              First Paragraph
Partnership             First Paragraph
Properties GP           Recitals
Properties LP           Recitals
Securities ACT          Section 3.4


      SECTION 1.3.CONSTRUCTION. Whenever the context requires, the gender of all
words used herein shall include the masculine, feminine and neuter, and the
number of all words shall include the singular and plural.

                                       3


      SECTION 1.4.REFERENCES. Unless specified, references in this Agreement to
"Sections", "Subsections", "Paragraphs" or "Articles" refer to the sections,
subsections, paragraphs or articles in this Agreement.

                                  ARTICLE II.
                     CONTRIBUTION BY OWNERS OF PROPERTIES LP

SECTION 2.1.CAPITALIZATION OF THE GENERAL PARTNER.

      (a)At the Closing, pursuant to the Investor's Agreement, Management will
contribute $288.30 to the General Partner to retain its 0.01% interest in the
General Partner as general partner.

      (b) At the Closing, pursuant to the Investor's Agreement,

            (i) EVMP will contribute the entire membership interest in
      Properties GP and a 3.44% limited partnership interest in Properties LP to
      the General Partner, in exchange for a 71.24% interest as a limited
      partner in the General Partner;

            (ii) Investors will contribute $144,150 to the General Partner in
      exchange for a 5.00% interest as a limited partner in the General Partner;

            (iii) EnCap Fund V will contribute a 0.66% interest in Properties LP
      to the General Partner in exchange for a 13.26% interest as a limited
      partner in the General Partner; and

            (iv) EnCap Fund V-B will contribute a 0.52% interest in Properties
      LP to the General Partner in exchange for a 10.49% interest as a limited
      partner in the General Partner.

      SECTION 2.2 CAPITALIZATION OF THE PARTNERSHIP.

      (a) At the Closing, pursuant to the Investor's Agreement, the General
Partner will contribute the entire membership interest in Properties GP, a 4.63%
limited partnership interest in Properties LP and $144,150 in cash to the
Partnership. In exchange for the contribution contemplated by this Section
2.2(a), the General Partner will retain its 2.00% general partnership interest
in the Partnership and will be issued the Incentive Distribution Rights by the
Partnership and be admitted as a limited partner with respect to such Incentive
Distribution Rights.

      (b) At the Closing, pursuant to the Investor's Agreement,

                  (i) EVMP will contribute a 4.27% limited partnership interest
            in Properties LP to the Partnership in exchange for 25,244 Common
            Units and a cash payment of $2,072,327.22, less its share of
            expenses, if any, in excess of $2.0 million.

                                       4


                  (ii) EVOC will contribute a 54.03% limited partnership
            interest in Properties LP to the Partnership in exchange for 138,381
            Common Units, 810,030 Subordinated Units (which will be issued to
            and held by EVH) and a cash payment of $14,519,564.03, less its
            share of expenses, if any, in excess of $2.0 million.

                  (iii) Investors will contribute a 5.00 % limited partnership
            interest in Properties LP to the Partnership in exchange for 155,000
            Subordinated Units.

                  (iv) EnCap Fund V will contribute a 17.95% limited partnership
            in interest Properties LP to the Partnership in exchange for 49,207
            Common Units, 243,350 Subordinated Units and a cash payment of
            $4,989,634.21, less its share of expenses, if any, in excess of $2.0
            million.

                  (v) EnCap Fund V-B will contribute a 14.21% limited
            partnership in interest in Properties LP to the Partnership in
            exchange for 38,913 Common Units, 192,820 Subordinated Units and a
            cash payment of $3,945,853.41, less its share of expenses, if any,
            in excess of $2.0 million.

                  (vi) CGAS will contribute a 99.99% limited partnership
            interest in Clinton LP to the Partnership in exchange for 343,255
            Common Units, 1,698,800 Subordinated Units (which will be issued to
            and held by CGH) and a cash payment of $34,806,771.14, less its
            share of expenses, if any, in excess of $2.0 million.

                                  ARTICLE III.
                         REPRESENTATIONS AND WARRANTIES

      SECTION 3.1 REPRESENTATIONS AND WARRANTIES OF ALL PARTIES.

      Each of the parties to this Agreement hereby represents and warrants
severally as to itself to each other party as follows:

            (a) Formation and Good Standing. That it is a corporation, limited
      partnership or limited liability company legally incorporated or formed,
      duly organized, validly existing and, if applicable, in good standing
      under the laws of the state of its formation and that it is duly qualified
      to do business and is in good standing as a foreign corporation,
      partnership or other entity in each jurisdiction where the character of
      the properties owned or leased by it or the nature of the businesses
      transacted by it requires it to be so qualified.

            (b) Authority, Execution and Enforceability. That it has full
      corporate, partnership or other power and authority to enter into this
      Agreement and to perform its obligations hereunder. That its execution,
      delivery and performance of this Agreement and the consummation of the
      transactions contemplated hereby have been duly authorized and approved by
      it. That it has duly executed and delivered this Agreement, and that this
      Agreement constitutes its legal, valid and binding obligation, enforceable
      against it in accordance with its terms (except as enforceability may be
      limited by

                                       5


      applicable bankruptcy, insolvency, reorganization, moratorium or similar
      laws affecting creditors' rights generally or by the principles governing
      the availability of equitable remedies).

            (c) No Conflicts. Neither its execution, delivery nor performance of
      this Agreement will:

                  (i) require the approval or consent of any Governmental
            Authority;

                  (ii) conflict with or result in the breach or violation of any
            term or provision of, or will constitute a default under, or will
            otherwise impair the good standing, validity or effectiveness of,
            any provision of its certificate or articles of incorporation,
            by-laws, partnership agreement or other formation documents;

                  (iii) result in the breach or violation by it of any material
            term or provision of, or constitute a default or give rise to any
            right of termination, cancellation or acceleration under any of the
            terms, conditions or provisions of any material agreement to which
            it is bound or by which its property or business is affected, except
            for such defaults (or rights of termination, cancellation or
            acceleration) as to which requisite waivers or consents are intended
            to be obtained by it prior to the Closing; or

                  (iv) violate any federal, state or local or other governmental
            law ordinance, or any order, writ, injunction, decree, rule or
            regulation of any Governmental Authority applicable to it.

      SECTION 3.2 REPRESENTATIONS OF EVMP REGARDING PROPERTIES LP, PROPERTIES
GP, CLINTON AND CLINTON GP. EVMP hereby represents and warrants to the
Partnership and General Partner at and as of the Closing Date as follows:

            (a) Organization and Good Standing of Properties GP and Clinton GP.
      Each of Properties GP and Clinton GP is a limited liability company
      legally formed, duly organized, validly existing and in good standing
      under the laws of the state of Delaware, and has full corporate power and
      authority and all necessary licenses and permits to own, lease and operate
      the properties used in its business and to act as the general partner of
      Properties LP or Clinton LP (as the case may be). Each of Properties GP
      and Clinton GP is duly qualified to do business and is in good standing as
      a foreign limited liability company in each jurisdiction where the
      character of the properties owned or leased by it or the nature of the
      businesses transacted by it requires it to be so qualified.

            (b) Organization and Good Standing of Properties LP and Clinton LP.
      Properties LP and Clinton LP each is a limited partnership legally formed,
      duly organized, validly existing and in good standing under the laws of
      the state of Delaware, with full corporate power and authority and all
      necessary licenses and permits to own, lease and operate the properties
      used in its business and to engage in the businesses it is currently
      engaged in. Properties LP and Clinton LP each is duly qualified to do
      business and is in good standing as a foreign limited partnership in each
      jurisdiction where the

                                       6


      character of the properties owned or leased by it or the nature of the
      businesses transacted by it requires it to be so qualified.

            (c) Organization and Good Standing of Subsidiaries of Properties LP.
      Schedule 3.2 sets forth the name and state of incorporation or formation
      of each subsidiary of Properties LP (each a "SUBSIDIARY"). Each Subsidiary
      is a limited liability company, a limited partnership or other entity
      legally formed, duly organized, validly existing and, if applicable, in
      good standing under the laws of the state of its formation, with full
      power and authority and all necessary licenses and permits to own, lease
      and operate the properties used in its business and to engage in the
      businesses it is currently engaged in. Each Subsidiary is duly qualified
      to do business and is in good standing as a foreign limited partnership in
      each jurisdiction where the character of the properties owned or leased by
      it or the nature of the businesses transacted by it requires it to be so
      qualified. All of the equity interests in each Subsidiary are owned,
      directly or indirectly, by Properties LP.

      SECTION 3.3 REPRESENTATIONS OF EVMP REGARDING CAPITALIZATION AND OWNERSHIP
OF PROPERTIES GP, PROPERTIES LP, CLINTON GP AND CLINTON LP. EVMP represents to
the Partnership as follows:

            (a) Capitalization of Properties GP and Clinton GP. The authorized
      capitalization of Properties GP and Clinton GP consist of an unlimited
      number of membership interests. All of the outstanding membership
      interests of Properties GP and Clinton GP are be validly issued, fully
      paid and nonassessable, and will be owned beneficially and of record, in
      the case of Properties GP, by EVMP, and in the case of Clinton GP, by a
      Subsidiary. Other than as contemplated by this Agreement, there are not
      any outstanding agreements, warrants, options, calls, preemptive or other
      rights, or other commitments of any nature which obligate Properties GP or
      Clinton GP to issue any additional membership interests. Other than as
      provided in the limited liability company agreement for Properties GP or
      Clinton GP, and under applicable law, there are no obligations on the part
      of the owners of membership interests of Properties GP or Clinton GP to
      make any capital contributions to Properties GP or Clinton GP or to loan
      funds to Properties GP or Clinton GP.

            (b) Capitalization of Properties LP. The authorized capitalization
      of Properties LP consists of a 0.01% general partnership interest and a
      99.99% limited partnership interest, each of which were validly issued.
      The entire general partnership interest of Properties LP is owned
      beneficially and of record by Properties GP, and the record owners of
      Properties LP are set forth on Schedule 3.3. There are not any outstanding
      agreements, warrants, options, calls, preemptive or other rights, or other
      commitments of any nature which obligate Properties LP to issue additional
      general or limited partnership interests. Other than as provided in the
      partnership agreement for Properties LP, and under applicable law, there
      are no obligations on the part of the general or limited partner of
      Properties LP to make any capital contributions to Properties LP or to
      loan funds to Properties LP.

                                        7


            (c) Capitalization of Clinton. The authorized capitalization of
      Clinton LP consists of a 0.01% general partnership interest and a 99.99%
      limited partnership interest, each of which were validly issued. The
      entire general partnership interest in Clinton LP is owned beneficially
      and of record by Clinton GP, and the record owner of the entire limited
      partnership interest is CGAS. There are not any outstanding agreements,
      warrants, options, calls, preemptive or other rights, or other commitments
      of any nature which obligate Clinton LP to issue additional general or
      limited partnership interests. Other than as provided in the partnership
      agreement for Clinton LP and under applicable law, there are no
      obligations on the part of the general or limited partner of Clinton LP to
      make any capital contributions to Clinton LP or to loan funds to Clinton
      LP.

      SECTION 3.4 REPRESENTATIONS AND WARRANTIES OF EVMP REGARDING OWNERSHIP AND
TRANSFER OF INTERESTS IN PROPERTIES GP AND PROPERTIES LP. EVMP hereby represents
and warrants to the General Partner and Partnership as follows:

            (a) Properties GP is the sole general partner of Properties LP.
      Properties GP is the record and beneficial owner of a 0.01% general
      partner interest in Properties LP, free and clear of any restrictions on
      transfer (other than any restrictions under applicable organizational or
      formation documents, the Securities Act of 1933, as amended ("SECURITIES
      ACT") and state securities laws), security interests, options, warrants,
      purchase rights, contracts, commitments, equities, liens, claims,
      encumbrances and demands (collectively, "CLAIMS").

            (b) EVMP is the record and beneficial owner of the entire membership
      interest in Properties GP free and clear of any Claims. EVMP is not a
      party to any option, warrant, purchase right, or other contract or
      commitment that could require EVMP to sell, transfer, or otherwise dispose
      of any ownership interest in Properties GP (other than this Agreement and
      the Investor's Agreement). EVMP is not a party to any voting trust, proxy,
      or other agreement or understanding with respect to the voting of any
      ownership interest in Properties GP. Upon transfer by EVMP of the
      membership interests in Properties GP to the General Partner as
      contemplated by this Agreement, the General Partner will acquire the
      membership interests in Properties GP, free and clear of any Claims
      created by EVMP.

            (c) EVMP is the record and beneficial owner of a 7.71% limited
      partnership interest in Properties LP, free and clear of any Claims. EVMP
      is not a party to any option, warrant, purchase right, or other contract
      or commitment that could require EVMP to sell, transfer, or otherwise
      dispose of any ownership interest in Properties LP (other than this
      Agreement and the Investor's Agreement). EVMP is not a party to any voting
      trust, proxy, or other agreement or understanding with respect to the
      voting of any ownership interest in Properties LP. Upon transfer by EVMP
      of the limited partnership interests in Properties LP to the General
      Partner and the Partnership as contemplated by this Agreement, the General
      Partner or the Partnership (as the case may be) will acquire the limited
      partnership interests in Properties LP, free and clear of any Claims
      created by EVMP.

                                       8


      SECTION 3.5 REPRESENTATIONS AND WARRANTIES OF EVOC REGARDING OWNERSHIP AND
TRANSFER OF INTERESTS IN PROPERTIES LP. EVOC represents and warrants to the
Partnership as follows:

            (a) EVOC is the record and beneficial owner of a 54.03% limited
      partnership interest in Properties LP, free and clear of any Claims. EVOC
      is not a party to any option, warrant, purchase right, or other contract
      or commitment that could require EVOC to sell, transfer, or otherwise
      dispose of any ownership interest in Properties LP (other than this
      Agreement and the Investor's Agreement). EVOC is not a party to any voting
      trust, proxy, or other agreement or understanding with respect to the
      voting of any ownership interest in Properties LP. Upon transfer by EVOC
      of the limited partnership interests in Properties LP to the General
      Partner and the Partnership as contemplated by this Agreement, the General
      Partner or the Partnership (as the case may be) will acquire the limited
      partnership interests in Properties LP, free and clear of any Claims
      created by EVMP.

      SECTION 3.6 REPRESENTATION AND WARRANTIES OF ENCAP FUNDS REGARDING
OWNERSHIP AND TRANSFER OF INTERESTS IN PROPERTIES LP. The EnCap Funds represent
and warrant to the General Partner and the Partnership as follows:

            (a) Each EnCap Fund is the record and beneficial owner of a the
      limited partnership interest in Properties LP set forth opposite its name
      on Schedule 3.6, free and clear of any Claims. An EnCap Fund is not a
      party to any option, warrant, purchase right, or other contract or
      commitment that could require the EnCap Fund to sell, transfer, or
      otherwise dispose of any ownership interest in Properties LP (other than
      this Agreement and the Investor's Agreement). An EnCap Fund is not a party
      to any voting trust, proxy, or other agreement or understanding with
      respect to the voting of any ownership interest in Properties LP. Upon
      transfer by the EnCap Fund of the limited partnership interests in
      Properties LP to the General Partner and the Partnership as contemplated
      by this Agreement, the General Partner or the Partnership (as the case may
      be) will acquire the limited partnership interests in Properties LP, free
      and clear of any Claims created by EVMP.

      SECTION 3.7 REPRESENTATIONS AND WARRANTIES OF CGAS REGARDING OWNERSHIP AND
TRANSFER OF INTERESTS IN CLINTON LP. CGAS hereby represents and warrants to the
Partnership as follows:

            (a) CGAS is the record and beneficial owner of a 99.99% limited
      partnership interest in Clinton LP, free and clear of any Claims. CGAS is
      not a party to any option, warrant, purchase right, or other contract or
      commitment that could require CGAS to sell, transfer, or otherwise dispose
      of any ownership interest in Clinton LP (other than this Agreement and the
      Investor's Agreement). CGAS is not a party to any voting trust, proxy, or
      other agreement or understanding with respect to the voting of any
      ownership interest in Clinton LP. Upon transfer by CGAS of the limited
      partnership interests in Clinton LP to the Partnership as contemplated by
      this Agreement, the Partnership will acquire the limited partnership
      interests in Clinton LP, free and clear of any Claims created by CGAS.

                                       9


      SECTION 3.8 REPRESENTATIONS AND WARRANTIES OF INVESTORS REGARDING
OWNERSHIP AND TRANSFER OF INTERESTS IN PROPERTIES LP. Investors is the record
and beneficial owner of a 5.00% limited partnership interest in Properties LP,
free and clear of any Claims. Investors is not a party to any option, warrant,
purchase right, or other contract or commitment that could require Investors to
sell, transfer, or otherwise dispose of any ownership interest in Properties LP
(other than this Agreement and the Investor's Agreement). Investors is not a
party to any voting trust, proxy, or other agreement or understanding with
respect to the voting of any ownership interest in Properties LP. Upon transfer
by Investors of the limited partnership interests in Properties LP to the
General Partner and the Partnership as contemplated by this Agreement, the
General Partner or the Partnership (as the case may be) will acquire the limited
partnership interests in Properties LP, free and clear of any Claims created by
Investors.

      SECTION 3.9 REPRESENTATIONS AND WARRANTIES OF THE GENERAL PARTNER
REGARDING INTERESTS ISSUED. The General Partner hereby represents and warrants
to each person acquiring a limited partnership interest in the General Partner
pursuant to this Agreement, as follows:

            (a) When issued and paid for as contemplated by this Agreement, the
      limited partnership interests in the General Partner will have been duly
      and validly when issued in compliance with the provisions of this
      Agreement and the GP Partnership Agreement, will be validly issued, fully
      paid and non-assessable. Such limited partnership interests are not
      subject to any preemptive rights or rights of first refusal.

      SECTION 3.10 REPRESENTATIONS AND WARRANTIES OF THE PARTNERSHIP REGARDING
COMMON AND SUBORDINATED UNITS. The Partnership hereby represents and warrants to
each person acquiring Common Units or Subordinated Units pursuant this
Agreement, as follows:

            (a) When issued and paid for as contemplated by this Agreement, the
      Common Units and Subordinated Units representing limited partnership
      interests in the Partnership will have been duly and validly when issued
      in compliance with the provisions of this Agreement and the GP Partnership
      Agreement, will be validly issued, fully paid and non-assessable. Such
      Common Units and Subordinated Units are not subject to any preemptive
      rights or rights of first refusal.

      SECTION 3.11 REPRESENTATIONS AND WARRANTIES OF EVMP, EVOC, THE ENCAP FUNDS
AND CGAS REGARDING SECURITIES LAWS. Each of EVMP, EVOC, the EnCap Funds,
Investors and CGAS, severally as to itself, hereby represents to the General
Partner and the Partnership, as follows:

            (a) It is acquiring its interest in the General Partner or
      Partnership under this Agreement for its own account for investment and
      not with a view towards the resale, transfer or distribution thereof, nor
      with any present intention of distributing the interest. Investor
      understands that the interest in the General Partner, the Common Units,
      the Subordinated Units and the Incentive Distribution Rights are
      "restricted securities" as defined in Rule 144 under the Securities Act.

            (b) It has such knowledge and experience in financial and business
      matters that it is capable of evaluating the merits and risks of its
      investment in the General partner

                                       10


      and the Partnership as contemplated by this Agreement, and is able to bear
      the economic risk of such investment for an indefinite period of time. It
      has been furnished access to such information and documents as it has
      requested and has been afforded an opportunity to ask questions of and
      receive answers from representatives of the General Partner and the
      Partnership concerning the terms and conditions of this Agreement and an
      investment in the General Partner and the Partnership.

            (c) It is an "accredited investor" as defined in Rule 501(a)
      promulgated under the Securities Act and has such knowledge and experience
      in financial and business matters that it is fully capable of evaluating
      the risks and merits of its investment under this Agreement in the General
      Partner and the Partnership.

                                   ARTICLE IV.
                                    COVENANTS

      SECTION 4.1 CONSENT TO ADMISSION AS A MEMBER OR PARTNER. Each of EVMP,
EVOC, CGAS, Investors, EnCap Fund V and EnCap Fund V-B, with respect to the
limited partner interest in Properties LP and Clinton LP transferred by it, and
the membership interests in Properties GP transferred by it, hereby grants to
the assignee of such interest the right to be admitted to Properties LP or
Clinton LP as a substitute limited partner, or to Properties GP as a substitute
member. Each limited partner of Properties LP and Clinton LP, and each member of
Properties GP, hereby consents to such admission as a substitute limited partner
or member, as the case may be. The General Partner, with respect to the
membership interest in Properties GP and the limited partnership interest in
Properties LP transferred by it, hereby grants to the Partnership the right to
be admitted to Properties GP as a substitute member and to Properties GP as a
substitute limited partner. Each member of Properties GP and each partner of
Properties LP hereby consent to such admission as a substitute limited partner
or member, as the case may be.

      SECTION 4.2 FURTHER ASSURANCES. Subject to the terms and conditions of
this Agreement, each of the parties hereto will use all reasonable efforts to
take, or cause to be taken, all action, and to do, or cause to be done, all
things necessary, proper or advisable, under applicable laws and regulations to
fulfill its obligations under this Agreement and to consummate and make
effective the transactions contemplated by this Agreement.

      SECTION 4.3 CONVEYANCE OF THE CLINTON PROPERTIES. CGAS agrees that prior
to the Closing, it will convey the Clinton Properties to Clinton LP pursuant to
the Clinton Conveyance.

                                   ARTICLE V.
                                   THE CLOSING

      SECTION 5.1 THE CLOSING. The closing of the transactions herein
contemplated ("CLOSING") shall be held at the offices of Haynes and Boone,
L.L.P., One Houston Center, Suite 2100, Houston, Texas 77002 contemporaneously
with the execution of this Agreement.

      SECTION 5.2 DELIVERIES AT CLOSING BY SOLE MEMBER OF PROPERTIES GP, LIMITED
PARTNERS OF PROPERTIES LP AND PROPERTIES GP AND CGAS. At the Closing,

                                       11


            (a) EVMP, as the sole member of Properties GP, shall deliver to the
      General Partner an assignment of the entire membership interest in
      Properties GP;

            (b) Each of EVMP, Investors, EnCap Fund V and EnCap Fund V-B shall
      deliver to the General Partner (i) an assignment of the limited
      partnership interest in Properties LP being assigned to the General
      Partner by such party as contemplated by this Agreement (ii) a duly
      executed counterpart of the GP Partnership Agreement; and

            (c) Each of EVMP, EVOC, Investors, CGAS, EnCap Fund V and EnCap Fund
      V-B shall deliver to the Partnership an assignment of the limited
      partnership interest in Properties LP being assigned to the Partnership by
      such party as contemplated by this Agreement.

      SECTION 5.3 DELIVERIES AT CLOSING BY GENERAL PARTNER. At the Closing,

            (a) The General Partner shall deliver to the Partnership an
      assignment of the entire membership interests in Properties GP and the
      portion of the limited partnership interest in Properties LP assigned to
      it pursuant to this Agreement; and

            (b) The General Partner shall deliver to each of EVMP, Investors,
      EnCap Fund V and EnCap Fund V-B a counterpart, duly executed by it, of the
      GP Partnership Agreement.

      SECTION 5.4 DELIVERIES AT CLOSING BY THE PARTNERSHIP. At the Closing,

            (a) The Partnership shall deliver to each of EVMP, EVOC, Investors,
      CGAS, EnCap Fund V and EnCap Fund V-B a duly executed copy of the MLP
      Partnership Agreement;

            (b) The Partnership shall deliver to each of EVH, Investors, CGH,
      EnCap Fund V and EnCap Fund V-B certificates representing the Common Units
      and Subordinated Units to which such party is entitled under this
      Agreement;

            (c) The Partnership will wire transfer to each of EVMP, EVOC, CGAS,
      EnCap Fund V and EnCap Fund V-B to the accounts specified by such party
      the cash payment to which such party is entitled under this Agreement in
      immediately available funds, less their proportionate share of $2.0
      million to pay expenses, if any, in excess of $2.0 million.

            (d) Within 30 days after the Closing Date, the Partnership will wire
      transfer to each of EVMP, EVOC, CGAS, EnCap Fund V and EnCap Fund V-B,
      their proportionate share of the $2.0 million retained pursuant to Section
      5.4(c) to the extent not used to pay expenses in excess of $2.0 million.

                                  ARTICLE VI.
                                  MISCELLANEOUS

      SECTION 6.1 HEADINGS. The section headings herein are for convenience of
reference only, do not constitute part of this Agreement and shall not be deemed
to limit or otherwise affect any of the provisions hereof.

                                       12


      SECTION 6.2 NOTICES. Unless otherwise provided herein, all notices or
other communications required or permitted hereunder shall be given in writing
and shall be hand delivered or sent by registered or certified mail, postage
prepaid, at the address opposite such party's name on the signature page hereof
or such other address as shall be furnished in writing by such party in
accordance with this Section 6.2, and any such notice or communication shall be
effective and be deemed to have been given as of the date so delivered or
received.

      SECTION 6.3 ASSIGNMENT. This Agreement and all of the provisions hereof
shall be binding upon and inure to the benefit of the parties hereto and their
respective successors and permitted assigns, provided, however, that neither
this Agreement nor any of the rights, interests or obligations hereunder may be
assigned by a party hereto without the prior written consent of all other
parties.

      SECTION 6.4 ENTIRE AGREEMENT. This Agreement (including Schedules hereto)
embody the entire agreement and understanding of the parties with respect to the
transactions contemplated hereby and supersede all prior written or oral
commitments, arrangements or understandings with respect thereto. There are no
restrictions, agreements, promises, warranties, covenants or undertakings with
respect to the transactions contemplated hereby other than those expressly set
forth herein or therein.

      SECTION 6.5 COUNTERPARTS. This Agreement may be executed in two or more
counterparts, all of which shall be considered one and the same agreement and
each of which shall be deemed an original.

      SECTION 6.6 GOVERNING LAW. This Agreement shall be governed by the laws of
the State of Texas (regardless of the laws that might be applicable under
principles of conflicts of law) as to all matters including, but not limited to
matters of validity, construction, effect and performance.

      SECTION 6.7 SEVERABILITY. If any one or more of the provisions of this
Agreement shall be held to be invalid, illegal or unenforceable, the validity,
legality or enforceability of the remaining provisions of this Agreement shall
not be affected thereby. To the extent permitted by applicable law, each party
waives any provision of law which renders any provision of this Agreement
invalid, illegal or unenforceable in any respect.

      SECTION 6.8 NO SURVIVAL OF REPRESENTATIONS AND WARRANTIES AND COVENANTS.
All representations, warranties, covenants, agreements and obligations contained
in this Agreement, or in any Schedule, certificate, document or statement
delivered pursuant hereto, shall terminate at the Closing and shall not survive
the Closing. No party hereto shall have any liability to any other party or any
other person by reason of this Agreement following the Closing, except for
intentional and knowing breach of a representation or warranty.

                                       13


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

                               ENERVEST MANAGEMENT PARTNERS, LTD.

                               By: EnerVest Management GP, L.C.,
                                   a Texas limited liability company,
                                   its General Partner

                               By: /s/ Mark A. Houser
                                   ----------------------------------------
                                   Mark A. Houser
                                   Executive Vice President and
                                   Chief Operating Officer

                               ENERVEST OPERATING, L.L.C.

                               By: /s/ Mark A. Houser
                                   ----------------------------------------
                                   Mark A. Houser
                                   President

                               EV INVESTORS, L.P.

                               By: EnerVest Management Partners, Ltd.
                                   its General Partner

                               By: EnerVest Management GP, L.C.,
                                   a Texas limited liability company,
                                   its General Partner

                               By: /s/ Mark A. Houser
                                   ----------------------------------------
                                   Mark A. Houser
                                   Executive Vice President and
                                   Chief Operating Officer

                               CGAS EXPLORATION, INC.

                               By: /s/ Mark A. Houser
                                   ----------------------------------------
                                   Mark A. Houser
                                   President and Chief Operating Officer

                                       14


                               CGAS PROPERTIES, L.P.

                               By: EVCG, L.L.C.
                                   A Delaware limited liability company,
                                   its General Partner

                               By: EV Properties L.P.
                                   a Delaware limited partnership,
                                   its Sole Member

                               By: EV Properties GP, LLC
                                   a Delaware limited liability company,
                                   its General Partner

                               By: EnerVest Management Partners, Ltd.,
                                   a Texas limited partnership,
                                   its sole Member

                               By: EnerVest Management GP, L.C.,
                                   a Texas limited liability company,
                                   its General Partner

                               By: /s/ Mark A. Houser
                                   ----------------------------------------
                                   Mark A. Houser
                                   Executive Vice President and
                                   Chief Operating Officer

                               EVCG GP, LLC

                               By: EV Properties L.P.
                                   a Delaware limited partnership,
                                   its Sole Member

                               By: EV Properties GP, LLC
                                   a Delaware limited liability company,
                                   its General Partner

                               By: EnerVest Management Partners, Ltd.,
                                   a Texas limited partnership,
                                   its sole Member

                               By: EnerVest Management GP, L.C.,
                                   a Texas limited liability company,
                                   its General Partner

                               By: /s/ Mark A. Houser
                                   ----------------------------------------
                                   Mark A. Houser
                                   Executive Vice President and
                                   Chief Operating Officer

                                       15


                               ENCAP ENERGY CAPITAL FUND V, L.P.,
                               a Texas limited partnership

                           By: EnCap Equity Fund V GP, L.P.,
                               a Texas limited partnership,
                               its General Partner

                           By: EnCap Investments L.P.,
                               a Delaware limited partnership,
                               its General Partner

                           By: EnCap Investments GP, L.L.C.,
                               a Delaware limited liability company,
                               its General Partner

                           By: /s/ Gary R. Petersen
                               -----------------------------------------
                           Name: Gary R. Petersen
                           Title: Senior Managing Director

                           ENCAP V-B ACQUISITIONS, L.P.,
                           a Texas limited partnership

                           By: EnCap V-B Acquisitions GP, LLC,
                               a Texas limited liability company,
                               its General Partner

                           By: EnCap Energy Capital Fund V-B, L.P.,
                               a Texas limited partnership,
                               its Sole Member

                           By: EnCap Equity Fund V GP, L.P.,
                               a Texas limited partnership,
                               its General Partner

                           By: EnCap Investments L.P.,
                               a Delaware limited partnership,
                               its General Partner

                           By: EnCap Investments GP, L.L.C.,
                               a Delaware limited liability company,
                               its General Partner

                           By: /s/ Gary R. Petersen
                               -----------------------------------------
                           Name: Gary R. Petersen
                           Title: Senior Managing Director

                                       16


                           EV ENERGY PARTNERS, L.P.

                           By: EV Energy GP, L.P.,
                               A Delaware limited partnership,
                               its General Partner

                           By: EV Management, L.L.C.,
                               A Delaware limited liability company,
                               its General Partner

                           By: /s/ Michael E. Mercer
                               --------------------------------------------
                               Michael E. Mercer
                               Senior Vice President and
                               Chief Financial Officer

                           EV ENERGY GP, L.P.

                           By: EV Management, L.L.C.,
                               a Delaware limited liability company
                               its General Partner

                           By: /s/ Michael E. Mercer
                               --------------------------------------------
                               Michael E. Mercer
                               Senior Vice President and
                               Chief Financial Officer

                           EV MANAGEMENT, L.L.C.

                           By: /s/ Michael E. Mercer
                               --------------------------------------------
                               Michael E. Mercer
                               Senior Vice President and
                               Chief Financial Officer

                           EVEC HOLDINGS, LLC

                           By: EnerVest Management Partners, Ltd.,
                               a Texas limited partnership,
                               its Sole Member

                           By: EnerVest Management GP, L.C.,
                               a Texas limited liability company,
                               its General Partner

                           By: /s/ Mark A. Houser
                               ----------------------------------------
                               Mark A. Houser
                               Executive Vice President and
                               Chief Operating Officer

                                       17


                           CGAS HOLDINGS LLC

                           By: CGAS Exploration, Inc.,
                               an Ohio corporation,
                               its Sole Member

                           By: /s/ Mark A. Houser
                               ----------------------------------------
                               Mark A. Houser
                               President and Chief Operating Officer

                                       18


                                  SCHEDULE 3.2

                          SUBSIDIARIES OF PROPERTIES LP



Name                                                                  State of Formation
- ----                                                                  ------------------
                                                                   
EnerVest WV, L.P.                                                           Delaware

EnerVest Production Partners, L.P.                                          Delaware

EVWV GP, LLC                                                                Delaware

EVPP GP, LLC                                                                Delaware

Lower Cargas Operating Company                                              Louisiana

EnerVest Cargas, Ltd.                                                       Texas


                                        1



                                  SCHEDULE 3.3

                         RECORD OWNERS OF PROPERTIES LP


                                                                   
EV Investors, L.P.                                                     5.00%

EnCap Fund V                                                          18.56%

EnCap Fund V-B                                                        14.69%

EnerVest                                                               7.71%

EVOC                                                                  54.03%


                                        1



                                  SCHEDULE 3.6

                            ENCAP OWNERSHIP PERCENTS


                                                                      
EnCap Fund V                                                             18.56

EnCap Fund V-B                                                           14.69


                                        1