CONTRIBUTION AGREEMENT

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                                                                    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

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                                Table of Contents
<TABLE>
<CAPTION>
                                                                               Page
                                                                           -------------
<S>                                                                        <C>
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
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<TABLE>
<S>                                                                        <C>
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
</TABLE>

                                       ii
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                             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;

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      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.

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      "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:

<TABLE>
<CAPTION>
Term                    Section
------------            ----------
<S>                     <C>
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
</TABLE>

      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.

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      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.

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                  (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

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      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