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                                                                   EXHIBIT 10.13


                                    Amendment
                                       To
           Non-Qualified Retirement/Savings Plan of Apache Corporation

Apache Corporation ("Apache") maintains the Non-Qualified Retirement/Savings
Plan of Apache Corporation (the "Plan"). Pursuant to section 8.02 of the Plan,
Apache has retained the right to amend the Plan. Apache hereby exercises that
right, effective as of the dates set forth below.

1.   Effective as of September 1, 2000, section 1.06(a)(v) shall be replaced in
     its entirety by the following.

                  (E)      Salary reductions that are excludable from an
                           Employee's gross income pursuant to Code section 125
                           or 132(f)(4), and

2.   Effective as of July 1, 2001, section 5.01(c)(v) shall be replaced in its
     entirety by the following.

         (v)      Change of Control. All Participants shall be fully vested if a
                  "change in control" occurs. For purposes of this paragraph, a
                  "change of control" shall mean the event occurring when a
                  person, partnership, or corporation, together with all
                  persons, partnerships, or corporations acting in concert with
                  each person, partnership, or corporation, or any or all of
                  them, acquires more than 20% of Apache's outstanding voting
                  securities; provided that a change of control shall not occur
                  if such persons, partnerships, or corporations acquiring more
                  than 20% of Apache's voting securities is solicited to do so
                  by Apache's board of directors, upon its own initiative, and
                  such persons, partnerships, or corporations have not
                  previously proposed to acquire more than 20% of Apache's
                  voting securities in an unsolicited offer made either to
                  Apache's board of directors or directly to the stockholders of
                  Apache.



IN WITNESS WHEREOF, this Amendment has been executed the date set forth below.

                                        APACHE CORPORATION


                                        By: /s/ Jeffrey M. Bender
                                            ------------------------------------

Date: August 3, 2001                    Title: Vice President - Human Resources
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