Exhibit
10.5




FOURTH
AMENDMENT TO AMENDED AND RESTATED CREDIT AGREEMENT




This
Fourth Amendment to Amended and Restated Credit Agreement (hereinafter referred
to as the “Amendment”) executed
as of July 28, 2006, by and among Clayton Williams Energy Inc., a Delaware
corporation (“CWEI”), Southwest
Royalties, Inc. (successor by merger to CWEI-SWR, Inc.), a Delaware corporation
(“SWR”, and
together with CWEI and each of their respective successors and permitted
assigns, the “Borrowers” and each a
“Borrower”),
Warrior Gas Co., a Texas corporation (“Warrior”), CWEI
Acquisitions, Inc. a Delaware corporation (“CWEI Acquisitions”),
Romere Pass Acquisition L.L.C., a Delaware limited liability company (“Romere”), CWEI Romere
Pass Acquisition Corp., a Delaware corporation (“Romere Corp”), Blue
Heel Company, a Delaware corporation (“Blue Heel”), and
Tex-Hal Partners, Inc., a Delaware corporation (“Tex-Hal,” and
together with Warrior, CWEI Acquisitions, Romere, Romere Corp and Blue Heel and
each of their successors and permitted assigns, the “Guarantors” and each
a “Guarantor”),
JPMorgan Chase Bank, N.A. (successor by merger to Bank One, N.A.
(Illinois)), a national banking association (“JPMorgan Chase”),
each of the financial institutions which is a party hereto (as evidenced by the
signature pages to this Amendment) or which may from time to time become a party
to the Agreement pursuant to the provisions of Section 14.3 thereof or any
successor or permitted assignee thereof (hereinafter collectively referred to as
“Lenders”, and
individually, “Lender”), JPMorgan
Chase, as Administrative Agent (in its capacity as Administrative Agent and
together with its successors in such capacity, “Administrative
Agent”).  Capitalized terms used but not defined in this
Amendment have the meanings assigned to such terms in that certain Amended and
Restated Credit Agreement dated as of May 21, 2004, by and among Borrowers,
Guarantors, Administrative Agent and Lenders (as amended, supplemented or
otherwise modified from time to time, the “Agreement”).




WITNESSETH:




WHEREAS,the Borrowers and the
Guarantors have requested that the Administrative Agent and the Lenders amend
the Agreement to permit the investment of up to $10,000,000 in a newly formed
partnership with a unit of General Electric Corporation through West Coast
Energy Properties GP, LLC, a newly formed subsidiary of CWEI and the general
partner of such partnership; and the Administrative Agent and the Lenders (or at
least the requisite percentage thereof) have agreed to do so on the terms and
conditions hereinafter set forth; and




NOW, THEREFORE, for and in
consideration of the mutual covenants and agreements herein contained and other
good and valuable consideration, the receipt and sufficiency of which are hereby
acknowledged and confessed, the Borrowers, the Guarantors, the Administrative
Agent and the Lenders, hereby agree as follows:




SECTION
1.       Amendments to the
Agreement.  Subject to the satisfaction or waiver in writing of
each condition precedent set forth in Section 2
hereof, and in reliance on the representations, warranties, covenants and
agreements contained in this Amendment, the Agreement shall be amended in the
manner provided in this Section 1.




Fourth
Amendment to Amended and Restated Credit Agreement – Page 1
 45803239.3


1.1           Additional Definitions.Article I of the
Agreement shall be and it hereby is amended by adding the following definition
in the correct alphabetical order:




“West
Coast Properties” means West Coast Energy Properties, L.P., a Texas limited
partnership and its successors.




1.2           Investments.  Section 8.15
of the Agreement shall be and it hereby is amended by replacing clause (ix)
of such Section with the following clauses (ix) and (x):




(ix)           Investments
in West Coast Properties, including equity contributions, and loans, advances or
other extensions of credit to West Coast Properties; provided that the amount of
such Investments made pursuant to this clause (ix) of Section 8.15
does not exceed in the aggregate, $10,000,000 and the proceeds of such
Investments are used by West Coast Properties to acquire and develop Oil and Gas
Interests.




(x)           Other
Investments not otherwise described in clauses (i) through (ix) above; provided
that, the aggregate amount of all other Investments made pursuant to this clause
(x) outstanding at any time shall not exceed $1,000,000 (calculated based on the
original cost of such Investment).




SECTION
2.       Conditions.  The
amendments to the Agreement contained in Section 1 of
this Amendment shall be effective upon the satisfaction of each of the
conditions set forth in this Section 2.




2.1           Execution and
Delivery.  Each Borrower and each Guarantor shall have executed
and delivered this Amendment.




2.2           Representations and
Warranties.  The representations and warranties of each
Borrower under the Agreement, as amended by the Amendment are true and correct
in all material respects as of such date, as if then made (except to the extent
that such representations and warranties relate solely to an earlier
date).




2.3           No Event of
Default.  No Event of Default shall have occurred and be
continuing nor shall any event have occurred or failed to occur which, with the
passage of time or service of notice, or both, would constitute an Event of
Default.




2.4           Partnership
Documents.  Borrowers shall have delivered to Administrative
Agent true and correct copies of the partnership agreement of West Coast Energy
Properties, L.P., a Texas limited partnership and all other documents,
agreements, instruments and certificates executed and delivered in connection
with the formation and capitalization of such partnership.




2.5           Other
Documents.  The Administrative Agent shall have received such
other instruments and documents incidental and appropriate to the transaction
provided for herein as the Administrative Agent or its special counsel may
reasonably request, and all such documents shall be in form and substance
satisfactory to the Administrative Agent.




Fourth
Amendment to Amended and Restated Credit Agreement – Page 2
 45803239.3


SECTION
3.       Representations and Warranties of
Borrowers.  To induce the Lenders to enter into this Amendment,
the Borrowers hereby represent and warrant to the Lenders as
follows:




3.1           Reaffirmation of Representations and
Warranties/Further Assurances.  After giving effect to the
amendments herein, each representation and warranty of any Borrower or any
Guarantor contained in the Agreement or in any of the other Loan Documents is
true and correct in all material respects on the date hereof (except to the
extent such representations and warranties relate solely to an earlier
date).




3.2           Corporate Authority; No
Conflicts.  The execution, delivery and performance by each
Borrower and each Guarantor (to the extent a party hereto or thereto) of this
Amendment and all documents, instruments and agreements contemplated herein are
within each such Borrower’s or such Guarantor’s corporate or other
organizational powers, have been duly authorized by necessary action, require no
action by or in respect of, or filing with, any court or agency of government
and do not violate or constitute a default under any provision of any applicable
law or other agreements binding upon any Borrower or any Guarantor or result in
the creation or imposition of any Lien upon any of the assets of any Borrower or
any Guarantor except for Permitted Liens and otherwise as permitted in the
Agreement.




3.3           Enforceability.  This
Amendment constitutes the valid and binding obligation of each Borrower and each
Guarantor enforceable in accordance with its terms, except as (i) the
enforceability thereof may be limited by bankruptcy, insolvency or similar laws
affecting creditor’s rights generally, and (ii) the availability of equitable
remedies may be limited by equitable principles of general
application.




SECTION
4.        Miscellaneous.




4.1           Reaffirmation of Loan Documents and
Liens.  Any and all of the terms and provisions of the
Agreement and the Loan Documents shall, except as amended and modified hereby,
remain in full force and effect.  Each Borrower hereby agrees that the
amendments and modifications herein contained shall in no manner affect or
impair the liabilities, duties and obligations of such Borrower or any Guarantor
under the Agreement and the other Loan Documents or the Liens securing the
payment and performance thereof.




4.2           Parties in
Interest.  All of the terms and provisions of this Amendment
shall bind and inure to the benefit of the parties hereto and their respective
successors and assigns.




4.3           Legal Expenses.  The
Borrowers hereby agree, jointly and severally, to pay all reasonable fees and
expenses of counsel to the Administrative Agent incurred by the Administrative
Agent in connection with the preparation, negotiation and execution of this
Amendment and all related documents.




4.4           Counterparts.  This
Amendment may be executed in one or more counterparts and by different parties
hereto in separate counterparts each of which when so executed and delivered
shall be deemed an original, but all such counterparts together shall constitute
but one and the same instrument; signature pages may be detached from multiple
separate counterparts and attached to a single counterpart so that all signature
pages are physically attached to the same




Fourth
Amendment to Amended and Restated Credit Agreement – Page 3
 45803239.3


document.  However,
this Amendment shall bind no party until the Borrowers, the Guarantors, the
Lenders (or at least the requisite percentage thereof), and the Administrative
Agent have executed a counterpart.  Delivery of photocopies of the
signature pages to this Amendment by facsimile or electronic mail shall be
effective as delivery of manually executed counterparts of this
Amendment.




4.5           Complete
Agreement.  THIS AMENDMENT, THE AGREEMENT, AND THE OTHER LOAN
DOCUMENTS REPRESENT THE FINAL AGREEMENT BETWEEN THE PARTIES AND MAY NOT BE
CONTRADICTED BY EVIDENCE OF PRIOR, CONTEMPORANEOUS OR ORAL AGREEMENTS OF THE
PARTIES.  THERE ARE NO UNWRITTEN ORAL AGREEMENTS BETWEEN THE
PARTIES.




4.6           Headings.  The
headings, captions and arrangements used in this Amendment are, unless specified
otherwise, for convenience only and shall not be deemed to limit, amplify or
modify the terms of this Amendment, nor affect the meaning thereof.




[Signature
Pages Follow]


Fourth
Amendment to Amended and Restated Credit Agreement – Page 4
 45803239.3


IN WITNESS WHEREOF, the
parties have caused this Fourth Amendment to Amended and Restated Credit
Agreement to be duly executed as of the date first above written.




BORROWERS:
              CLAYTON
      WILLIAMS ENERGY, INC.
              a
      Delaware corporation
              By:_____________________________
              Mel
      G. Riggs, Senior Vice President and Chief Financial
  OfficerSOUTHWEST
      ROYALTIES, INC.
              a
      Delaware limited liability company
              By:_____________________________
              Mel
      G. Riggs, Vice PresidentGUARANTORS:
              WARRIOR
      GAS CO.
              a
      Texas corporation
              By:_____________________________
              Mel
      G. Riggs, Vice PresidentCWEI
      ACQUISITIONS, INC.
              a
      Delaware corporation
              By:_____________________________
              Mel
      G. Riggs, Vice PresidentROMERE
      PASS ACQUISITION L.L.C.
              a
      Delaware limited liability company
              By:_____________________________
              Mel
      G. Riggs, Vice PresidentCWEI
      ROMERE PASS ACQUISITION CORP.
              By:_____________________________
              Mel
      G. Riggs, Vice PresidentBLUE
      HEEL COMPANY
              a
      Delaware corporation
              By:_____________________________
              Mel
      G. Riggs, Vice PresidentTEX-HAL
      PARTNERS, INC.
              a
      Delaware corporation
              By:_____________________________
              Mel
      G. Riggs, Vice PresidentJPMORGAN CHASE BANK,
      N.A.,
              (successor
      by merger to Bank One, N.A. (Illinois)), as Administrative Agent and
      a Lender
              By:_____________________________
              Name:                      Wm.
      Mark Cranmer
              Title:                      Senior
      Vice PresidentBANK
      OF SCOTLAND
              as
      Co-Agent and a Lender
              By:_____________________________
              Name:
              Title:UNION
      BANK OF CALIFORNIA, N.A.
              as
      Syndication Agent and a Lender
              By:_____________________________
              Name:
              Title:
              By:_____________________________
              Name:
              Title:BNP
      PARIBAS
              as
      Documentation Agent and a Lender
              By:_____________________________
              Name:
              Title:
              By:_____________________________
              Name:
              Title:FORTIS CAPITAL
      CORP.
              as
      a Lender
              By:_____________________________
              Name:
              Title:
              By:_____________________________
              Name:
              Title:COMERICA
      BANK
              as
      a Lender
              By:_____________________________
              Name:
              Title:GUARANTY
      BANK
              as
      a Lender
              By:_____________________________
              Name:
              Title:





NATEXIS
      BANQUES POPULAIRES
              as
      a Lender
              By:_____________________________
              Name:
              Title:
              By:_____________________________
              Name:
              Title:





BANK
      OF TEXAS, N.A.
              as
      a Lender
              By:_____________________________
              Name:
              Title: