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                                                                   EXHIBIT 10.16

                                    Amendment
                                       To
                     Apache Corporation 401(k) Savings Plan

         Apache Corporation ("Apache") maintains the Apache Corporation 401(k)
Savings Plan (the "Plan"). Pursuant to section 10.4 of the Plan, Apache has
retained the right to amend the Plan. Apache hereby exercises that right by
replacing subsection 6.6(b) of the Plan with the following, effective January 1,
1999.

                  (b) Definition of Eligible Rollover Distribution. For purposes
         of this section only, an "eligible rollover distribution" is any
         distribution or in-service withdrawal other than (i) distributions
         required under Code section 401(a)(9), (ii) distributions of amounts
         that have already been subject to federal income tax (such as defaulted
         loans or after-tax voluntary contributions), (iii) installment payments
         in a series of substantially equal payments made at least annually and
         (A) made over a specified period of ten or more years, (B) made for the
         life or life expectancy of the distributee, or (C) made for the joint
         life or joint life expectancy of the distributee and his or her
         designated beneficiary, (iv) a distribution to satisfy the limits of
         Code section 415 or 402(g), (v) a distribution to satisfy ADP, ACP, or
         multiple use tests, (vi) any other actual or deemed distribution
         specified in the regulations issued under Code section 402(c); or (vii)
         any hardship withdrawal by an Employee under age 59 1/2 pursuant to
         subsection 7.1(c).


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


                                        APACHE CORPORATION


                                        By: /s/ Daniel L. Schaeffer
                                           ------------------------------------
         Date: October 21, 1999         Title: Vice President, Human Resources
               ----------------               ---------------------------------


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                                    Amendment
                                       To
                     Apache Corporation 401(k) Savings Plan

         Apache Corporation ("Apache") maintains the Apache Corporation 401(k)
Savings Plan (the "Plan"). Apache filed the Plan with the IRS on September 15,
1998 in order to obtain a favorable determination as to the qualified status of
the Plan. The IRS granted the Plan a favorable determination letter dated August
13, 1999, contingent on certain amendments being made to the Plan. In section
10.4 of the Plan, Apache reserved the right to amend the Plan from time to time.
Apache hereby exercises such right as follows.

         1. Effective as of January 1, 1999, section 1.14 shall be replaced in
its entirety by the following.

         1.14 "Covered Employee" means any Employee of the Company, with the
following exceptions.


                  (a) Any individual directly employed by an entity other than
         the Company shall not be a Covered Employee, even if such individual is
         considered a common-law employee of the Company or is treated as an
         employee of the Company pursuant to Code section 414(n).

                  (b) A non-resident alien shall not be a Covered Employee.

                  (c) An Employee included in a unit of Employees covered by a
         collective bargaining agreement shall not be a Covered Employee unless
         the collective bargaining agreement specifically provides for such
         Employee's participation in the Plan.

                  (d) An Employee whose job is classified as "temporary" shall
         be a Covered Employee only after he or she has worked for the Company
         and Affiliated Entities for six consecutive months.

                  (e) An Employee shall not be a Covered Employee while he or
         she is classified as an "intern," a "consultant," or an "independent
         contractor." An Employee may be classified as an "intern" only if he or
         she is currently enrolled (or the Company expects him or her to be
         enrolled within the next 12 months) in a high school, college, or
         university. An Employee may be classified as an intern even if he or
         she does not receive academic course credit from his or her school for
         this employment with the Company.

                  (f) An individual who is employed pursuant to a written
         agreement with an agency or other third party for a specific job
         assignment or project shall not be a Covered Employee.



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         2. Effective as of January 1, 1997, the last sentence of section 1.18
shall be replaced by the following sentence.

         The term "Employee" shall also include any individual who provides
         services to the Company or an Affiliated Entity pursuant to an
         agreement between the Company or an Affiliated Entity and a third party
         that employs the individual, but only if the individual has performed
         such services for the Company or an Affiliated Entity on a
         substantially full-time basis for at least one year and only if the
         services are performed under the primary direction or control by the
         Company or an Affiliated Entity; provided, however, that if the
         individuals included as Employees pursuant to the first part of this
         sentence constitute 20% or less of the Non-Highly Compensated Employees
         of the Company and Affiliated Entities, then any such individuals who
         are covered by a qualified plan that is a money purchase pension plan
         that provides a nonintegrated employer contribution rate for each
         participant of at least 10% of compensation, that provides for full and
         immediate vesting, and that provides immediate participation for each
         employee of the third party (other than those who perform substantially
         all of their services for the third party and other than those whose
         compensation from the third party during each of the four preceding
         plan years was less than $1000) shall not be considered an Employee.

         3. Effective as of January 1, 1997, section 1.23 shall be replaced in
its entirety by the following.

         1.23 "Highly Compensated Employee" means, for each Plan Year, an
         Employee who (a) had Compensation of $80,000 (as adjusted by the
         Secretary of the Treasury) or more during the immediately preceding
         Plan Year, or (b) is a Five-Percent Owner during the current Plan Year,
         or (c) was a Five-Percent Owner during the immediately preceding Plan
         Year. The term "Highly Compensated Employee" shall also include, where
         the context so requires, any former Employee who was a Highly
         Compensated Employee when he or she separated from service with the
         Company and all Affiliated Entities, as well as any former Employee who
         was a Highly Compensated Employee at any time after attaining age 55.

         4. Effective as of January 1, 1999, the last sentence of subsection
3.5(b) shall be replaced in its entirety by the following.

         The Committee may elect to exclude from the ADP test those Non-Highly
         Compensated Employees who, at the end of the Plan Year, had not
         attained age 21 and/or whose Period of Service was for less than one
         year.




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         5. Effective as of January 1, 1997, subsection 3.5(e) shall be replaced
in its entirety by the following two subsections.

                  (e) Order of Correction. The method described in subsection
         (c) shall be employed first, during the Plan Year. If that method is
         not used during the Plan Year, or if the net effect of such method was
         insufficient for the ADP test to be satisfied, the Company has the
         discretion to use any one or more of the methods described in
         paragraphs (d)(i), (d)(ii), and (d)(iii). If the Company does not
         choose to make the corrections described in paragraphs (d)(i), (d)(ii),
         and (d)(iii), or if such corrections are insufficient to satisfy the
         ADP test, then the correction method described in paragraph (d)(iv)
         shall be used.

                  (f) Calculating the Amounts Returned. If the ADP test is not
         satisfied, and Participant Before-Tax Contributions are returned
         pursuant to paragraph (d)(iv) above, the Committee shall determine the
         amount to be returned pursuant to paragraph (i) below, and shall then
         allocate that amount among the Highly Compensated Employees pursuant to
         paragraph (ii) below. The amount actually returned to each Highly
         Compensated Employee shall be adjusted to reflect as nearly as possible
         the actual investment gains or losses thereon for the Plan Year,
         determined pursuant to Article IV, but shall not be adjusted to reflect
         any subsequent gains or losses.

                           (i) Calculation of Amount of Excess Contributions.
                  The amount of Participant Before-Tax Contributions to be
                  returned to the group of Highly Compensated Employees as a
                  whole (the "excess contributions") shall be equal to the
                  hypothetical reduction in the Participant Before-Tax
                  Contributions that are subject to the ADP test pursuant to
                  subsection (b) (the "relevant Participant Before-Tax
                  Contributions") that would be made under the following
                  procedure. The Highly Compensated Employee(s) with the highest
                  "actual deferral ratio" has an amount hypothetically returned
                  until his or her actual deferral ratio is reduced to the
                  actual deferral ratio of the Highly Compensated Employee with
                  the next highest actual deferral ratio; this process is
                  repeated to the extent necessary for the ADP test to be
                  satisfied. The term "actual deferral ratio" is a fraction, the
                  denominator of which is equal to the Participant's
                  Compensation, and the numerator of which is equal to
                  (A)+(B)+(C)-(D)-(E), where

                           (A) is equal to the Participant's Participant
                           Before-Tax Contributions for the Plan Year.

                           (B) is equal to that portion of the Participant's
                           QNECs and QMACs that are allocated to the Participant
                           as of any date


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                           within the Plan Year, but only to the extent that the
                           Committee elects to include them in the ADP test.

                           (C) is equal to zero for a Non-Highly Compensated
                           Employee, and, for each Highly Compensated Employee
                           who participates in a cash or deferred arrangement
                           sponsored by the Company or an Affiliated Entity that
                           is permitted to be aggregated with this Plan, is
                           equal to the contributions to the other plan that are
                           subject to that plan's ADP test.

                           (D) is equal to any of the amounts in (A) that are
                           used in the ACP test pursuant to subsection (b).

                           (E) is equal to any of the amounts in (A) or (B) or
                           (C) that have been removed from the Participant's
                           Accounts pursuant to any other corrective mechanisms
                           described in this Article.

                           (ii) Allocation of Excess Contributions. The excess
                  contributions shall be allocated among the Highly Compensated
                  Employees as follows. The Highly Compensated Employee(s) with
                  the largest relevant Participant Before-Tax Contributions
                  shall have an amount returned until his or her remaining
                  employer contributions are equal to those of the Highly
                  Compensated Employee with the next largest relevant
                  Participant Before-Tax Contributions. This process is repeated
                  until the excess contributions have been completely returned
                  to the Highly Compensated Employees. For each Highly
                  Compensated Employee who receives a return of excess
                  contributions, the Plan shall first return his or her
                  unmatched Participant Before-Tax Contributions (if any) before
                  returning any of his or her matched Participant Before-Tax
                  Contributions. If a matched Participant Before-Tax
                  Contribution is returned, the corresponding Company Matching
                  Contribution shall be forfeited (unless returned to the
                  Participant pursuant to paragraph 3.6(c)(vi)).

         6. Effective as of January 1, 1999, the last sentence of subsection
3.6(b) shall be replaced in its entirety by the following.

         The Committee may elect to exclude from the ACP test those Non-Highly
         Compensated Employees who, at the end of the Plan Year, had not
         attained age 21 and/or whose Period of Service was for less than one
         year.



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         5. Effective as of January 1, 1997, subsection 3.6(d) shall be replaced
in its entirety by the following two subsections.

                  (d) Order of Correction. The method described in subsection
         3.5(c) shall be employed first, during the Plan Year. If that method is
         not used during the Plan Year, or if the net effect of such method was
         insufficient for the ACP test to be satisfied, the Company has the
         discretion to use any one or more of the methods described in
         paragraphs (c)(i), (c)(ii), and (c)(iii). If the Company does not
         choose to make the corrections described in paragraphs (c)(i), (c)(ii),
         and (c)(iii), or if such corrections are insufficient to satisfy the
         ACP test, then the correction method described in paragraph (c)(v)
         shall be used if the Plan is top-heavy; if the Plan is not top-heavy,
         or if the corrections pursuant to (c)(v) are insufficient, the
         correction methods described in paragraphs (c)(iv), (c)(vi), and
         (c)(vii) shall be used, as described in subsection (e).

                  (e) Calculating the Corrective Reduction in Participants'
         Accounts. If the ACP test is not satisfied, and the correction methods
         described in paragraphs (c)(iv), (c)(vi), and (c)(vii) are to be used,
         the Committee shall determine the amount of the correction pursuant to
         paragraph (i) below, and shall then allocate that amount among the
         Highly Compensated Employees pursuant to paragraph (ii) below. The
         amount of the correction shall be adjusted to reflect as nearly as
         possible the actual investment gains or losses thereon for the Plan
         Year, determined pursuant to Article IV, but shall not be adjusted to
         reflect any subsequent gains or losses.

                           (i) Calculation of Amount of Excess Aggregate
                  Contributions. The term "aggregate contributions" means those
                  Participant Before-Tax Contributions and Company Matching
                  Contributions that are taken into account for the ACP test
                  pursuant to subsection (b). The amount of the excess aggregate
                  contributions shall be equal to the hypothetical reduction in
                  the aggregate contributions that would be made under the
                  following procedure. The Highly Compensated Employee(s) with
                  the highest "actual contribution ratio" has his or her
                  aggregate contributions hypothetically reduced until his or
                  her actual contribution ratio is lowered to the actual
                  contribution ratio of the Highly Compensated Employee with the
                  next highest actual contribution ratio; this process is
                  repeated to the extent necessary for the ACP test to be
                  satisfied. The term "actual contribution ratio" is a fraction,
                  the denominator of which is equal to the Participant's
                  Compensation, and the numerator of which is equal to
                  (A)+(B)+(C)+(D)-(E), where




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                           (A) is equal to the Participant's Company Matching
                           Contributions for the Plan Year.

                           (B) is equal to the Participant's Participant
                           Before-Tax Contributions that are used in the ACP
                           test pursuant to subsection (b).

                           (C) is equal to that portion of the Participant's
                           QNECs and QMACs that are allocated to the Participant
                           as of any date within the Plan Year, but only to the
                           extent that the Committee elects to include them in
                           the ACP test.

                           (D) is equal to zero for a Non-Highly Compensated
                           Employee, and, for each Highly Compensated Employee
                           who participates in a cash or deferred arrangement
                           sponsored by the Company or an Affiliated Entity that
                           is permitted to be aggregated with this Plan, is
                           equal to the contributions to the other plan that are
                           subject to that plan's ACP test.

                           (E) is equal to any of the amounts in (A) or (B) or
                           (C) or (D) that have been removed from the
                           Participant's Accounts pursuant to any other
                           corrective mechanisms described in this Article.

                           (ii) Allocation of Excess Aggregate Contributions.
                  The excess aggregate contributions shall be allocated among
                  the Highly Compensated Employees as follows. The Highly
                  Compensated Employee(s) with the largest aggregate
                  contributions shall have his or her aggregate contributions
                  reduced until his or her remaining aggregate contributions are
                  equal to those of the Highly Compensated Employee with the
                  next largest aggregate contributions. This process is repeated
                  until the excess aggregate contributions have been eliminated.
                  The reduction in aggregate contributions for each affected
                  Highly Compensated Employee shall be made in the following
                  order: unmatched Participant Before-Tax Contributions; then
                  matched Participant Before-Tax Contributions, together with
                  any associated Company Matching Contribution. Any reduction in
                  Company Matching Contributions shall be forfeited (to the
                  extent not vested) or paid to the Highly Compensated Employee
                  (to the extent vested).




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         6. Effective as of January 1, 1997, subsection 3.7(b) shall be replaced
in its entirety by the following.

                  (b) Corrections to Satisfy Multiple Use Test. If the multiple
         use test is not satisfied, the Company shall cause the contributions to
         the Accounts of the Highly Compensated Employees to be adjusted as
         follows. First, the Company may make certain contributions, or may
         designate certain contributions as QNECs or QMACs pursuant to
         subsections 3.5(d) and 3.6(c). Second, if additional correction is
         necessary, and the Plan is top-heavy, the correction method specified
         in paragraph 3.6(c)(v) shall be used. Third, if additional correction
         is necessary, the Committee shall make the following corrections for
         the appropriate Highly Compensated Employees: (i) return unmatched
         Participant Before-Tax Contributions; (ii) return matched Participant
         Before-Tax Contributions, and, for the associated Company Matching
         Contribution, forfeit it (to the extent not vested) or pay it to the
         Highly Compensated Employee (to the extent vested).

         7. Effective as of January 1, 1997, section 5.8 shall be replaced in
its entirety by the following.

                  A rehired Participant shall have two Company Contribution
         Accounts, an "old" Company Contributions Account for the contributions
         from his or her earlier episode of employment, and a "new" Company
         Contributions Account for his or her later episode of employment. The
         vested percentage applicable to such Accounts shall be determined
         pursuant to sections 5.1 and 5.6, unless an amount was distributed from
         the old Company Contributions Account before the Participant was
         rehired, in which case the vested percentage of the old Company
         Contributions Account, after any forfeiture has been restored to it,
         shall be determined pursuant to subsection 5.3(c). If a Participant
         becomes fully vested in both the old and the new Company Contributions
         Accounts, they shall be merged into one Company Contributions Account.

         8. Effective as of January 1, 1997, the last section 10.1 shall be
replaced in its entirety by the following.

                  Apache expects to continue the Plan indefinitely, but the
         continuance of the Plan and the payment of contributions are not
         assumed as contractual obligations. Apache may terminate the Plan or
         discontinue contributions at any time. Upon the termination of the Plan
         or the complete discontinuance of contributions, each Participant's
         Accounts shall become fully vested. Upon the partial termination of the
         Plan, the Accounts of all affected Participants shall become fully
         vested. The only Participants who are affected by a partial termination
         are those whose employment with the Company or Affiliated Entity is
         terminated as a result of the corporate event causing the partial
         termination;


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                  Employees terminated for cause and those who leave voluntarily
         are not affected by a partial termination.



                               EXECUTED this 21st day of October, 1999.

                                        APACHE CORPORATION


                                        By: /s/ Daniel L. Schaeffer
                                           -------------------------------------
                                         Title: Vice President, Human Resources
                                               ---------------------------------



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                                    Amendment
                                       To
                     Apache Corporation 401(k) Savings Plan

         Apache Corporation ("Apache") maintains the Apache Corporation 401(k)
Savings Plan (the "Plan"). Pursuant to section 10.4 of the Plan, Apache has
retained the right to amend the Plan. Apache hereby exercises that right by
replacing subsection 2.1(a) of the Plan with the following, effective January 1,
2000.

                  (a) Participant Before-Tax Contributions. A Covered Employee
         shall be eligible to begin to make Participant Before-Tax Contributions
         as of the first day of the first pay period of the month that begins
         after the day the Employee becomes a Covered Employee.


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


                                        APACHE CORPORATION


                                        By: Daniel L. Schaeffer
                                           ------------------------------------
         Date: December 30, 1999        Title: Vice President, Human Resources
               -----------------              ---------------------------------


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