EXHIBIT 4.39
                                                                    ------------


                            SECOND AMENDING AGREEMENT


THIS AGREEMENT dated as of July 31, 2002.

BETWEEN:

         NEXEN INC., a corporation subsisting under the laws of Canada
         (hereinafter referred to as the "BORROWER"),

                                                              OF THE FIRST PART,

                                     - and -

         THE FINANCIAL INSTITUTIONS SET FORTH ON THE SIGNATURE PAGE HEREOF UNDER
         THE HEADING "LENDERS:" (hereinafter collectively referred to as the
         "LENDERS" and sometimes individually referred to as a "LENDER"),

                                                             OF THE SECOND PART,

                                     - and -

         THE TORONTO-DOMINION BANK, a Canadian chartered bank, as agent of the
         Lenders (hereinafter referred to as the "AGENT"),

                                                              OF THE THIRD PART.


         WHEREAS the parties hereto entered into the Credit Agreement;

         AND WHEREAS the parties hereto have agreed to amend and supplement
certain provisions of the Credit Agreement as set out herein;

         AND WHEREAS the Lenders have agreed that the Agent execute this
Agreement on their behalf;

         NOW THEREFORE THIS AGREEMENT WITNESSES that in consideration of the
covenants and agreements herein contained and other good and valuable
consideration, the receipt and sufficiency of which are hereby conclusively
acknowledged by each of the parties hereto, the parties hereto covenant and
agree as follows:


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1.       INTERPRETATION

1.1      In this Agreement and the recitals hereto, unless something in the
subject matter or context is inconsistent therewith:

         "AGREEMENT" means this agreement, as amended, modified, supplemented or
         restated from time to time; and

         "CREDIT AGREEMENT" means the Restated Credit Agreement among the
         parties hereto originally made as of December 29, 1988 and amended and
         restated as of November 17, 2000, as amended by the First Amending
         Agreement made as of August 1, 2001 and as otherwise amended,
         supplemented, modified or restated from time to time.

1.2      Capitalized terms used herein without express definition shall have the
same meanings herein as are ascribed thereto in the Credit Agreement.

1.3      The division of this Agreement into Sections and the insertion of
headings are for convenience of reference only and shall not affect the
construction or interpretation of this Agreement. The terms "this Agreement",
"hereof", "hereunder" and similar expressions refer to this Agreement and not to
any particular Section or other portion hereof and include any agreements
supplemental hereto.

1.4      This Agreement shall be governed by and construed in accordance with
the laws of the Province of Alberta and federal laws of Canada applicable
therein.

2.       AMENDMENTS

2.1      The Credit Agreement is hereby amended as follows:

         (a)      the definition of "Maturity Date" in Section 1.1 is hereby
                  amended by deleting the word "fifth" in the second line and
                  substituting therefor the word "fourth"; and

         (b)      Clause (a) of Section 2.17 is amended as follows:

                  (i)      by deleting the number "6" in the second line and
                           substituting therefor the number "5"; and

                  (ii)     by deleting the number "5" in the tenth line and
                           substituting therefor the number "4".


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3.       REPRESENTATIONS AND WARRANTIES

         The Borrower hereby represents and warrants as follows to each Lender
and the Agent and acknowledges and confirms that each Lender and the Agent is
relying upon such representations and warranties:

         (a)      Capacity, Power and Authority

                  (i)      The Borrower is duly incorporated and is validly
                           subsisting under the laws of its jurisdiction of
                           incorporation or creation and has all the requisite
                           corporate capacity, power and authority to carry on
                           its business as presently conducted and to own its
                           property; and

                  (ii)     The Borrower has the requisite corporate capacity,
                           power and authority to execute and deliver this
                           Agreement.

         (b)      Authorization; Execution; Enforceability

                  The Borrower has taken or caused to be taken all necessary
                  action to authorize, and has duly executed and delivered this
                  Agreement. This Agreement is a legal, valid and binding
                  obligation of the Borrower, enforceable against it in
                  accordance with its terms, subject to applicable bankruptcy,
                  reorganization, winding up, insolvency, moratorium or other
                  laws of general application affecting the enforcement of
                  creditors rights generally and to the equitable and statutory
                  powers of the courts having jurisdiction with respect thereto.

                  The representations and warranties set out in this Agreement
                  shall survive the execution and delivery of this Agreement and
                  the making of each Drawdown, notwithstanding any
                  investigations or examinations which may be made by the Agent,
                  the Lenders or Lenders' counsel. Such representations and
                  warranties shall survive until the Credit Agreement has been
                  terminated.

4.       MATURITY DATE

         The parties hereto confirm that the Maturity Date shall continue to be
July 31, 2007.

5.       CONFIRMATION OF CREDIT AGREEMENT AND OTHER DOCUMENTS

         The Credit Agreement and all covenants, terms and provisions thereof,
except as expressly amended and supplemented by this Agreement, shall be and
continue to be in full force and effect. The Credit Agreement as amended and
supplemented by this Agreement is hereby ratified and confirmed and shall from
and after the date hereof continue in full force and effect as herein amended
and supplemented.


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6.       FURTHER ASSURANCES

         The parties hereto shall from time to time do all such further acts and
things and execute and deliver all such documents as are required in order to
effect the full intent of and fully perform and carry out the terms of this
Agreement.

7.       COUNTERPARTS

         This Agreement may be executed in any number of counterparts, and by
facsimile, each of which shall be deemed to be an original and all of which
taken together shall be deemed to constitute one and the same instrument, and it
shall not be necessary in making proof of this Agreement to produce or account
for more than one such counterpart.

         IN WITNESS WHEREOF the parties hereto have executed this Agreement.

BORROWER:                              LENDERS:

NEXEN INC.                             THE TORONTO-DOMINION BANK
                                       ROYAL BANK OF CANADA
                                       THE BANK OF NOVA SCOTIA
By: /s/ Charles Fischer                CANADIAN IMPERIAL BANK OF COMMERCE
    -----------------------------      BANK OF AMERICA, N.A.
     Name:    Charles Fischer
     Title:   President & CEO
                                       EACH OF THE FOREGOING LENDERS BY ITS DULY
By: /s/ Rick C. Beingessner            AUTHORIZED AGENT:
    -----------------------------
     Name:    Rick C. Beingessner
     Title:   Assistant Secretary
                                       THE TORONTO-DOMINION BANK, AS AGENT

                                       By:   /s/ Michael A. Freeman
                                             ----------------------------------
                                             Name:   Michael A. Freeman
                                             Title:  Vice President, Loan
                                                     Syndications - Agency
AGENT:

THE TORONTO-DOMINION BANK,
AS AGENT

By: /s/ Michael A. Freeman
    ------------------------------
     Name:   Michael A. Freeman
     Title:  Vice President, Loan
             Syndications - Agency