1




                            [PRIMARY CREDIT FACILITY]
================================================================================

              SECOND AMENDED AND RESTATED CREDIT FACILITY AGREEMENT

                                  by and among

                       PIONEER NATURAL RESOURCES COMPANY,
                                  as BORROWER,

                                       and

                               NATIONSBANK, N.A.,
                            as ADMINISTRATIVE AGENT,

                                       and

                                   CIBC INC.,
                             as DOCUMENTATION AGENT,

                                       and

                   MORGAN GUARANTY TRUST COMPANY OF NEW YORK,
                             as DOCUMENTATION AGENT,

                                       and

                   CHASE BANK OF TEXAS, NATIONAL ASSOCIATION,
                              as SYNDICATION AGENT,

                         THE CO-AGENTS SIGNATORY HERETO,

                                       and

                       THE OTHER LENDERS SIGNATORY HERETO

                           Dated as of March 19, 1999

                              ---------------------

                     NATIONSBANC MONTGOMERY SECURITIES LLC,
                        as LEAD ARRANGER and BOOK MANAGER

================================================================================


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              SECOND AMENDED AND RESTATED CREDIT FACILITY AGREEMENT

         THIS SECOND AMENDED AND RESTATED CREDIT FACILITY AGREEMENT (herein
called this "Amendment and Restatement"), is made as of March 19, 1999, by and
among PIONEER NATURAL RESOURCES COMPANY, a Delaware corporation (the
"Borrower"), NATIONSBANK, N.A., as successor-by-merger to NationsBank of Texas,
N.A., as Administrative Agent and Collateral Agent, CIBC INC., as Documentation
Agent, MORGAN GUARANTY TRUST COMPANY OF NEW YORK, as Documentation Agent, CHASE
BANK OF TEXAS, NATIONAL ASSOCIATION, as successor-in-interest to The Chase
Manhattan Bank, as Syndication Agent, the "Co-Agents" party to the Credit
Agreement (as herein defined), and the other Lenders from time to time parties
to the Credit Agreement.

                              W I T N E S S E T H:

         WHEREAS, the Borrower, the Lenders, the Managing Agents, the Collateral
Agent and the Co- Agents have heretofore entered into a certain Amended and
Restated Credit Facility Agreement - Primary Credit Facility, dated as of
December 18, 1997, as previously amended (herein the "Credit Agreement"); and

         WHEREAS, the Borrower, the Lenders, the Managing Agents, the Collateral
Agent and the Co- Agents now intend to amend and restate the Credit Agreement;
and

         NOW, THEREFORE, in consideration of the premises and the mutual
agreements herein contained, each of the Borrower, the Lenders, the Managing
Agents, the Collateral Agent and the Co-Agents hereby agree as follows:

         SECTION 1. Defined Terms. All capitalized terms used but not otherwise
defined herein shall have the meanings given in the Credit Agreement, as amended
and restated by the Amendment and Restatement.

         SECTION 2. Amendments to Credit Agreement. Effective as of Effective
Date, the Credit Agreement is hereby amended and restated in its current form
with the following amendments:

         a.             The definitions of "Amendment Fee Rate", "Applicable
                  Rating Level", "Consolidated Interest Expense", "EBITDAX",
                  "Eurodollar Margin" and "Facility Fee Rate" in Section 1.1 of
                  the Credit Agreement are hereby amended and restated to read
                  in their entirety as follows:

         "        "Amendment Fee Rate" means 37.5 basis points."

         "        "Applicable Rating Level" means the level set forth below that
         corresponds to the lowest of ratings issued from time to time by
         Moody's and S&P, as applicable to Borrower's senior, unsecured
         long-term debt:



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=======================================================
                        Moody's                S&P
- -------------------------------------------------------
                                      
Level I                 >= Baa3             >= BBB-
- -------------------------------------------------------
Level II                   Ba1                 BB+
- -------------------------------------------------------
Level III                  Ba2                 BB
- -------------------------------------------------------
Level IV                <= Ba3              <= BB-
=======================================================


         For example, if the Moody's rating is Ba1 and the S&P rating is BB,
         Level III shall apply.

                  For purposes of the foregoing, (i) ">=" means a rating more
         favorable than or equal to; "<=" means a rating less favorable than or
         equal to; (ii) if ratings for Borrower's senior unsecured long-term
         debt shall not be available from S&P or Moody's, Level IV shall be
         deemed applicable; (iii) if any of the Rating Agencies shall change its
         ratings nomenclature prior to the date all Obligations have been paid
         and the Commitments canceled, Borrower and the Lenders shall negotiate
         in good faith to amend the references to specific ratings in this
         definition to reflect such change, and pending such amendment, if an
         appropriate Applicable Rating Level is otherwise not determinable based
         upon the foregoing grid, the last Applicable Rating Level in effect at
         the time of such change shall continue to apply."

         "        "Consolidated Interest Expense" means, for any period, total
         interest expense, whether paid or accrued, of Borrower and its
         Subsidiaries on a Consolidated basis, including, without limitation,
         all commissions, discounts and other fees and charges owed with respect
         to Letters of Credit."

         "        "EBITDAX" means, for any period the sum of the amounts for
         such period of Consolidated net income (excluding gains and losses on
         the sale of assets), Consolidated Interest Expense, depreciation
         expense, depletion expense, amortization expense, federal and state
         income taxes, exploration and abandonment expense and other non-cash
         charges and expenses, all as determined on a Consolidated basis for
         Borrower and its Subsidiaries.

         "        "Eurodollar Margin" means, on any date, with respect to each
         Eurodollar Portion of a Revolving Loan, the sum of (i) the applicable
         Senior Debt Margin plus (ii) the number of basis points per annum set
         forth below based on the Applicable Rating Level and the applicable
         Total Leverage Ratio:



================================================================================
                                      Total Leverage Ratio
- --------------------------------------------------------------------------------
Applicable                               3.0 < "x" <= 4.0
Rating Level            "x" <= 3.0                    ---        "x" > 4.0
- --------------------------------------------------------------------------------
                                                        
   Level I              112.5 b.p.           125.0 b.p.          150.0 b.p.
- --------------------------------------------------------------------------------
   Level II             137.5 b.p.           150.0 b.p.          200.0 b.p.
- --------------------------------------------------------------------------------
   Level III            162.5 b.p.           187.5 b.p.          225.0 b.p.
- --------------------------------------------------------------------------------
   Level IV             200.0 b.p.           225 b.p.            250.0 b.p.
- --------------------------------------------------------------------------------




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         Changes in the Eurodollar Margin will occur automatically without prior
         notice (x) upon the effectiveness of any change of the Applicable
         Rating Level and (y) three (3) days following the earlier of (A) the
         date the Borrower delivers the certificate in respect of the previous
         Fiscal Quarter required pursuant to the second sentence of Subsection
         5.1(b)(1) (provided that for purposes of this definition, the Borrower
         shall be permitted to deliver a certificate sixty (60) days following a
         Fiscal Year containing the information to be included in the
         certificate to be delivered pursuant to Section 5.1(b)(1) except based
         upon unaudited financial statements for such Fiscal Year) or 5.1(b)(2),
         as the case may be and (B) sixty (60) days following the end of such
         previous Fiscal Quarter in the event of a change in the Total Leverage
         Ratio; provided that so long as the Debt Reduction Requirement is not
         satisfied, the Eurodollar Margin shall be based on a Total Leverage
         Ratio of greater than 4.0 to 1.0. Administrative Agent will give notice
         promptly to Borrower and the Lenders of changes in the Eurodollar
         Margin."

         "        "Facility Fee Rate" means, on any date that a facility fee is
         due pursuant to Section 2.7, the number of basis points per annum set
         forth below based on the Applicable Rating Level on such date;
         provided, that notwithstanding the provisions of Section 2.7, the
         facility fee payable to each Lender at the Facility Fee Rate pursuant
         to Section 2.7 for any period shall be payable on the average daily
         unused amount (which amount shall include any outstanding Swing Line
         Advances or Competitive Bid Advances) of such Lender's Percentage Share
         of the Facility Amount for such period:



                ====================================================
                     Applicable               Facility Fee Rate
                    Rating Level                    Margin
                ----------------------------------------------------
                                                
                       Level I                     37.5 b.p.
                ----------------------------------------------------
                       Level II                    50.0 b.p.
                ----------------------------------------------------
                       Level III                   50.0 b.p.
                ----------------------------------------------------
                       Level IV                    50.0 b.p.
                ====================================================



         Changes in the Facility Fee Rate will occur automatically without prior
         notice. Administrative Agent will give notice promptly to Borrower and
         the Lenders of changes in the Facility Fee Rate."

         b.            Section 1.1 of the Credit Agreement is hereby amended by
                  inserting the following definitions of "Base Rate Margin",
                  "Consolidated Tangible Net Worth", " Debt Issuance", "Debt
                  Reduction Requirement", "Engineering Report", "Initial
                  Engineering Report", "Net Cash Proceeds", "Non-Recourse Debt",
                  "Properties", "Properties NPV", "Properties NPV to Total Debt
                  Ratio", "Public Notes", "Qualified Investments", "Security
                  Documents", "Senior Debt", "Senior Debt Margin", "Senior
                  Leverage Ratio", "Subordinated Debt" and "Total Leverage
                  Ratio" in appropriate alphabetical order:




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         "        "Base Rate Margin" means, on any date, with respect to each
         Base Rate Portion of a Revolving Loan, the sum of (i) the applicable
         Senior Debt Margin plus (ii) the greater of (A) the Eurodollar Margin
         less 125 basis points or (B) zero."

         "        "Consolidated Tangible Net Worth" means (i) the Consolidated
         shareholder's equity of Borrower and its Subsidiaries (determined in
         accordance with GAAP), less (ii) the amount of Consolidated intangible
         assets of Borrower and its Subsidiaries, plus (iii) the aggregate
         amount of any non-cash write downs under Financial Accounting Standards
         19, 109 and 121, on a consolidated basis, by Borrower and its
         Subsidiaries after December 31, 1998."

         "        "Debt Issuance" means the sale or issuance after February 1,
         1999, by Borrower or any Restricted Person of notes or other debt
         securities for cash pursuant to a registration statement under the
         Securities Act of 1933, as amended (the "Act"), or to qualified
         institutional buyers in reliance on Rule 144A under the Act or pursuant
         to a transaction effected as private placement pursuant to an exemption
         to registration under the Act."

         "        "Debt Reduction Requirement" means that all of the following
         requirements shall have occurred (i) the expiration or termination in
         full of the commitments under, and the payment of all amounts under or
         in respect of, the 364 Day Facility, (ii) the reduction of the
         Commitments under this Agreement after February 1, 1999 by an aggregate
         amount of at least $325,000,000 and the payment of all Consolidated
         Total Funded Debt required to be paid as the result of such reduction
         and (iii) the maintenance of the Total Leverage Ratio at less than or
         equal to 4.25 to 1.00 for at least two consecutive Fiscal Quarters ,
         except that solely for purposes of Subsection 2.9(g) hereof,
         satisfaction of the Debt Reduction Requirement shall be determined
         using the following clause (iii) in lieu of the foregoing clause (iii):
         (iii) on the day on which the determination is made and after giving
         pro forma effect to any transaction occurring on such day (including
         repayment of Obligations to be made on such day) the ratio of (a)
         Borrower's then Consolidated Total Funded Debt to (b) Borrower's
         EBITDAX for the four (4) Fiscal Quarters most recently ended prior to
         such day is less than or equal to 4.25 to 1, after adjusting such
         EBITDAX on a pro forma basis for any assets or Property sold or
         acquired after the beginning of such most recently ended four Fiscal
         Quarters as if such assets or Property had been sold or acquired at the
         beginning of such four most recently ended Fiscal Quarters; provided
         that for purposes of the calculation in this clause (iii) for purposes
         solely of Section 2.9(g) hereof, (1) EBITDAX for the four Fiscal
         Quarters ending December 31, 1998 shall be deemed to be four times the
         EBITDAX for the Fiscal Quarter ending on such date after adjusting such
         EBITDAX on a pro forma basis for any assets or Property sold or
         acquired after the beginning of such Fiscal Quarter as if such assets
         or Property had been sold or acquired at the beginning of such Fiscal
         Quarter, (2) EBITDAX for the four Fiscal Quarters ending March 31, 1999
         shall be deemed to be two times the EBITDAX for the semi-annual period
         ending on such date after adjusting such EBITDAX on a pro forma basis
         for any assets or Property sold or acquired after the beginning of such
         semi-annual period ending on such date as if such assets or Property
         had been sold or acquired at the




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         beginning of such semi-annual period ending on such date and (3)
         EBITDAX for the four Fiscal Quarters ending June 30, 1999 shall be
         deemed to be the product of 4/3rds times EBITDAX for the three Fiscal
         Quarters ending on such date after adjusting such EBITDAX on a pro
         forma basis for any assets or Property sold or acquired after the
         beginning of such three Fiscal Quarters as if such assets or Property
         had been sold or acquired at the beginning of such three Fiscal
         Quarters."

         "        "Engineering Report" means the Initial Engineering Report and
         each other engineering report delivered pursuant to Section 5.1(b)(4)."

         "        "Initial Engineering Report" means that certain engineering
         report, delivered to the Administrative Agent on February 26, 1999
         concerning the Properties."

         "        "Net Cash Proceeds" means the cash or cash equivalent proceeds
         received by the Borrower or any Restricted Person as a result of (i) an
         issuance of common stock, preferred stock or other equity of the
         Borrower or any Restricted Person, (ii) a Debt Issuance, or (iii) a
         sale of Property of Borrower or any Restricted Person, in each case
         after deducting all of the following, as applicable, (a) legal fees
         paid or reimbursed by Borrower or any Restricted Person and allocable
         to such transaction, (b) underwriters' discounts, initial purchasers'
         discounts, placement agent's fees, brokers' commissions and other
         discounts, commissions or fees incurred in connection with such
         transaction, to the extent paid or reimbursed by Borrower or any
         Restricted Person, (c) registration fees, printer's fees and other
         costs of sale paid or reimbursed by Borrower or any Restricted Person
         in connection with such transaction, and (d) any reserves maintained by
         Borrower or any Restricted Person for any closing cost adjustments or
         similar contingencies in connection with such transaction. Proceeds of
         any such transaction consisting of notes, stock, securities or other
         non-cash assets or property shall not be included as Net Cash Proceeds;
         provided, however, any cash or cash equivalents received as a result of
         the sale, pledge or transfer of any such note, stock, securities or
         other non-cash assets or property or as a payment on account of or
         otherwise realized on account of principal or capital of any note,
         stock, securities or other non-cash assets or property (but not
         dividends, interest or operating income in respect of any assets or
         property) shall be treated as cash or cash equivalent proceeds received
         by Borrower or a Restricted Person at the time such cash or cash
         equivalent is received by Borrower or any Restricted Person."

         "        "Properties" means, at the particular time in question, all
         material oil and gas properties and reserves (which properties and
         reserves shall be free of any Liens other than Permitted Liens) of the
         Borrower and the Subsidiaries at such time and that were evaluated in
         the Initial Engineering Report or, if applicable, the Engineering
         Report and other information most recently provided by Borrower
         pursuant to Section 5.1(b)(4)."

         "        "Properties NPV" means, at the particular time in question,
         the net present value of the Borrower's and the Subsidiaries' proved
         reserves included in the Properties set forth in either (i) the Initial
         Engineering Report or (ii) if applicable, the Engineering Report most
         recently provided by Borrower pursuant to Section 5.1(b)(4)."



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         "        "Properties NPV to Total Debt Ratio" means at any time the
         ratio of (a) the Properties NPV to (b) Borrower's Total Debt."

         "        "Public Notes" means each of the following: (i) Borrower's
         $150,000,000 8 7/8% Senior Notes due 2005, (ii) Borrower's $150,000,000
         8 1/4% Senior Notes due 2007, (iii) Borrower's $350,000,000 6.50%
         Senior Notes due 2008, (iv) Borrower's $250,000,000 7.20% Senior Notes
         due 2028, together with all guaranties thereof and all notes issued
         from time to time in replacement therefor and (v) any other publicly
         tradeable notes, bonds or debentures outstanding as of February 1,
         1999, which notes, bonds or debentures by their terms require that they
         be secured equally and ratably with any collateral under this
         Agreement."

         "        "Qualified Investments" means (i) the purchase by Borrower or
         one of its Subsidiaries of Properties constituting proved reserves, or
         (ii) capital expenditures made by Borrower or one of its Subsidiaries
         to maintain, enhance or develop Properties constituting proved reserves
         owned by Borrower or one of its Subsidiaries."

         "        "Security Documents" means, collectively, the Mortgage, Deed
         of Trust, Assignment, Security Agreement and Financing Statement from
         the Borrower or any of its Subsidiaries as the case may be, granted to
         a Collateral Agent selected by the Administrative Agent and reasonably
         acceptable to Borrower to secure equally and ratably the Obligations
         and the Public Notes, substantially in the form attached hereto as
         Exhibit Q with appropriate insertions (with any modifications necessary
         to comply with applicable state laws or filing requirements), and any
         and all further documents, financing statements, agreements and
         instruments which may be required under applicable law, or which the
         Agent may reasonably request, in order to satisfy the requirements of
         Section 5.1(n)."

         "        "Senior Debt" means Total Funded Debt of the Borrower and its
         Subsidiaries, other than Total Funded Debt that is Subordinated Debt."

         "        "Senior Debt Margin" means, on any date, the number of basis
         points per annum set forth below based on the Senior Leverage Ratio on
         such date:


           ====================================================================
               Senior Leverage Ratio              "x" <= 4.25      "x" > 4.25
           --------------------------------------------------------------------
                                                               
            On or before August 3, 1999               0 b.p.         25.0 b.p.
           --------------------------------------------------------------------
            After August 3, 1999                      0 b.p.         50.0 b.p.
           ====================================================================


         Changes in the Senior Debt Margin will occur automatically without
         prior notice three (3) days following the earlier of (A) the date the
         Borrower delivers the certificate in respect of the previous Fiscal
         Quarter required pursuant to the second sentence of Subsection
         5.1(b)(1) (provided that for purposes of this definition, the Borrower
         shall be permitted to deliver a certificate sixty (60) days following a
         Fiscal Year containing the information




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         to be included in the certificate to be delivered pursuant to Section
         5.1(b)(1) except based upon unaudited financial statements for such
         Fiscal Year) or 5.1(b)(2), as the case may be and (B) sixty (60) days
         following the end of such previous Fiscal Quarter; provided that so
         long as the Debt Reduction Requirement is not satisfied, the Senior
         Debt Margin shall be based on a Senior Leverage Ratio of greater than
         4.25 to 1.0."

         "        "Senior Leverage Ratio" means at any time the ratio of (a)
         Borrower's then Consolidated Senior Debt to (b) Borrower's EBITDAX;
         provided that for purposes of the foregoing calculation, EBITDAX for
         any Fiscal Quarter shall be deemed to be four times the EBITDAX for
         such Fiscal Quarter."

         "        "Subordinated Debt" means all unsecured Debt of the Borrower
         for money borrowed which is subordinated in right of payment to the
         payment of all Obligations, upon customary terms satisfactory to the
         Administrative Agent."

         "        "Total Leverage Ratio" means at any time the ratio of (a)
         Borrower's then Consolidated Total Funded Debt to (b) Borrower's
         EBITDAX; provided that for purposes of the foregoing calculation,
         EBITDAX for any Fiscal Quarter shall be deemed to be four times the
         EBITDAX for such Fiscal Quarter."

         c.             Section 1.1 of the Credit Agreement is hereby amended by
                  deleting the following definitions of "Commitment
                  Utilization", "Commitment Utilization Level" and
                  "Commitment Utilization Margin" in their entirety.

         d.             The definition of "Debt" in Section 1.1 of the Credit
                  Agreement is hereby amended by adding the following to the end
                  of clause (h) before the semicolon: "and the amount of
                  deferred revenue attributable to any forward sale of
                  production or Properties for which such Person has directly or
                  indirectly received payment in advance."

         e.             Section 2.9 of the Credit Agreement is hereby amended
                  and restated to read in its entirety as follows:

         "        Section 2.9     Termination and Reduction of Commitments;
         Mandatory Prepayments.

                  (a) Unless previously terminated, the Commitments shall
         terminate on the Maturity Date.

                  (b) Borrower may at any time terminate, or from time to time
         reduce, the Commitments; provided that (i) each reduction of the
         Commitments shall be in an amount that is an integral multiple of
         $1,000,000 and not less than $5,000,000 and (ii) Borrower shall not
         terminate or reduce the Commitments if, after giving effect to any
         concurrent prepayment of the Loans in accordance with Section 2.10, the
         sum of (i) all Lenders' Revolving Loan Advances (including any
         Revolving Loan Advances to be made but not yet made pursuant to a
         Request for Advance) outstanding at any time plus (ii) the LC




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         Obligations of all Lenders at such time plus (iii) all Swing Line
         Advances to Borrower plus (iv) all Lenders' Competitive Bid Advances
         outstanding at such time, would exceed the total Commitments.

                  (c) Borrower shall notify the Administrative Agent of any
         election to terminate or reduce the Commitments under paragraph (b) of
         this Section at least two Business Days prior to the effective date of
         such termination or reduction, specifying such election and the
         effective date thereof. Promptly following receipt of any notice, the
         Administrative Agent shall advise the Lenders of the contents thereof.
         Each notice delivered by Borrower pursuant to this Section shall be
         irrevocable; provided that a notice of termination of the Commitments
         delivered by Borrower may state that such notice is conditioned upon
         the effectiveness of other credit facilities, in which case such notice
         may be revoked by Borrower (by notice to the Administrative Agent on or
         prior to the specified effective date) if such condition is not
         satisfied. Any termination or reduction of the Commitments shall be
         permanent.

                  (d) Upon the issuance of Debt permitted pursuant to Section
         5.2(a)(5), (i) the Commitments automatically and permanently shall be
         reduced by, (ii) the Loan Commitments of each Lender automatically and
         permanently shall be reduced on a pro-rata basis in an amount
         sufficient to reduce the aggregate amount of such Loan Commitments by,
         and (iii) the Borrower shall make a mandatory prepayment on the Loans
         on or within ten (10) days of such issuance in, an amount equal to 100%
         of the Net Cash Proceeds received by Borrower in connection with such
         issuance.

                  (e) Upon the issuance of any common stock, preferred stock or
         other equity of the Borrower or any Restricted Subsidiary, (i) the
         Commitments automatically and permanently shall be reduced by, and the
         Loan Commitments of each Lender automatically and permanently shall be
         reduced on a pro-rata basis in an amount sufficient to reduce the
         aggregate amount of such Loan Commitments by, an amount equal to 50% of
         the Net Cash Proceeds received by Borrower in connection with such
         issuance and (ii) the Borrower shall make a mandatory prepayment on the
         Loans on or within ten (10) days of such issuance in an amount equal to
         75% of the Net Cash Proceeds received by Borrower in connection with
         such issuance. In addition, unless Borrower provides evidence
         acceptable to the Administrative Agent that the Borrower and its
         Restricted Subsidiaries have made Qualified Investments in an amount of
         at least 25% of the Net Cash Proceeds of such issuance on or within 120
         days after the date of such issuance, then (x) the Commitments
         automatically and permanently shall be reduced by and (y) the Loan
         Commitments of each Lender automatically and permanently shall be
         reduced on a pro-rata basis in an amount sufficient to reduce the
         aggregate amount of such Loan Commitments by an amount equal to the
         difference of 25% of the Net Cash Proceeds received by Borrower in
         connection with such issuance minus the amount of such Qualified
         Investments of such proceeds by the Borrower and its Restricted
         Subsidiaries during such 120 day period.





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                  (f) Upon the sale, transfer, conveyance or assignments of any
         Properties of Borrower or its Restricted Subsidiaries, (i) the
         Commitments automatically and permanently shall be reduced by, and (ii)
         the Loan Commitments of each Lender automatically and permanently shall
         be reduced on a pro-rata basis in an amount sufficient to reduce the
         aggregate amount of such Loan Commitments by, 100% of the Net Cash
         Proceeds in excess of $25,000,000 in the aggregate for all such sales
         after February 1, 1999 received by Borrower in connection with such
         sale, transfer, assignment or conveyance and the Borrower shall make
         mandatory prepayments on the Loans on or within ten (10) days of such
         sale, transfer, assignment or conveyance to the extent necessary so
         that after giving effect to such mandatory prepayments the sum of (a)
         all Lenders' Revolving Loan Advances (including any Revolving Loan
         Advances to be made but not yet made pursuant to a Request for Advance)
         outstanding at any time plus (b) the LC Obligations of all Lenders at
         such time plus (c) all Swing Line Advances to Borrower plus (d) all
         Lenders' Competitive Bid Advances outstanding at such time, would not
         exceed the total Commitments.

                  (g) Notwithstanding anything to the contrary contained in this
         Agreement, no reduction in the Commitments or Loan Commitments shall be
         required pursuant to the provisions of paragraphs (d), (e), and (f) of
         this Section 2.9 to the extent that, and so long as, the Borrower has
         satisfied the Debt Reduction Requirement and no Default has occurred
         and is continuing.

                  (h) Notwithstanding any other provision of this Agreement, if
         during the period commencing February 1, 1999 and ending December 31,
         1999 the aggregate reductions in Commitments pursuant to the foregoing
         subsections of this Section 2.9 is less than $325,000,000, on December
         31, 1999 the Commitments shall be automatically reduced by the
         remainder of (i) $325,000,000 minus (ii) the total of all reductions in
         the Commitment pursuant to the foregoing subsections of this Section
         2.9 during such period, and Borrower shall make a mandatory prepayment
         on December 31, 1999 in an amount sufficient to cause the sum of (i)
         all Lenders' Revolving Loan Advances (including any Revolving Loan
         Advances to be made but not yet made pursuant to a Request for Advance)
         outstanding at such time plus (ii) the LC Obligations of all Lenders at
         such time plus (iii) all outstanding Swing Line Advances to Borrower
         plus (iv) all Lenders' Competitive Bid Advances outstanding at such
         time not to exceed the Total Commitments after giving effect to such
         reduction.

                  (i) Each reduction in Commitments pursuant to this Section 2.9
         shall be made ratably among the Lenders in accordance with their
         respective Commitments on the date of such reduction.

                  (j) To the extent that the Canadian Credit Facility contains
         requirements to reduce the Commitment Amount (as defined in the
         Canadian Credit Facility) and the Commitments (as defined in the
         Canadian Credit Facility) and to make prepayments in the circumstances
         described in the foregoing subsections (d), (e) and (f) of this Section
         2.9,




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         then the percentages 100%, 75% and 25%, respectively, in such
         subsections (d), (e) and (f) shall be deemed reduced to 80%, 60% and
         20%, respectively."

         f.                Section 4.1(h) of the Credit Agreement is hereby
                  amended by inserting at the end of Section 4.1(h) the
                  following sentence:

         "There are no statements or conclusions in any Engineering Report which
         are based upon or include misleading information or fail to take into
         account material information regarding the matters reported therein, it
         being understood that (1) each Engineering Report is necessarily based
         upon professional opinions, estimates and projections and (2) Borrower
         does not warrant that such opinions, estimates and projections will
         ultimately prove to have been accurate."

         g.                Section 5.1(b) of the Credit Agreement is hereby
                  amended by inserting after Section 5.1(b)(3) of the Credit
                  Agreement the following Sections 5.1(b)(4):

         "        (4)      By August 15th and February 15th of each Fiscal Year,
                           an Engineering Report prepared by the Borrower
                           covering all Properties constituting proved reserves
                           as of June 30th and December 31st, respectively, of
                           such Fiscal Year, based upon the Designated Lenders'
                           Assumptions. No later than thirty (30) days prior to
                           the date that an Engineering Report is required to be
                           delivered by Borrower pursuant to this subsection
                           5.1(b)(4), Administrative Agent (i) shall have
                           obtained from each of NationsBank, N.A., CIBC Inc.,
                           Morgan Guaranty Trust Company of New York, and Chase
                           Bank of Texas, National Association, as successor-in-
                           interest to The Chase Manhattan Bank, which is a
                           Lender under this Agreement on such day, each such
                           Lender's assumptions regarding future commodity
                           prices, including, as applicable, annual escalations
                           thereof or average prices for each future year, and
                           such Lender's discount factor for discounting to
                           present value future net revenues in each case as
                           utilized by such Lender in making its normal and
                           customary evaluation of the net present value of oil
                           and gas reserves of its borrowers generally and (ii)
                           shall have determined and provided to the Borrower
                           the average of such future price assumptions and
                           discount factors provided to the Administrative Agent
                           by such Lenders (such average being herein called the
                           "Designated Lenders' Assumptions").

         h.                Section 5.1 of the Credit Agreement is hereby amended
                  by inserting the following Section 5.1(n) after Section 5.1(m)
                  of the Credit Agreement:

         "        (n)      Springing Lien. In the event that (i) any Event of
         Default has occurred and is continuing or (ii) at any time after August
         3, 1999 the sum of (A) aggregate Commitments under this Agreement plus
         (B) the aggregate "Commitments" under the 364 Day Credit Facility,
         exceeds $775,000,000, then, without affecting in any way any




                                       10
   12

         other rights of the Lenders hereunder, the Administrative Agent, at the
         direction of the Required Lenders, may request that the Borrower, and
         the Borrower agrees to:

                                    (i) duly execute and deliver to the
                  Administrative Agent (or such other Person designated by the
                  Administrative Agent) the Security Documents and cause each
                  such Security Document to be filed, registered and recorded,
                  as the law may require or the Administrative Agent may
                  request, in each jurisdiction where so required or requested,
                  and deliver to the Administrative Agent an acknowledgment
                  copy, or other evidence satisfactory to it, of each such
                  filing, registration and recordation, in order to mortgage,
                  assign, grant a security interest in and pledge to the
                  Administrative Agent (or such other Person designated by the
                  Administrative Agent), acting on behalf of the Lenders, all of
                  the Borrower's and the Restricted Subsidiaries' right, title
                  and interest in and to the Properties located in the United
                  States, and the proceeds thereof, having a Properties NPV, as
                  of the date of the most recent Engineering Report, of 80% of
                  the aggregate Properties NPV attributable to Properties
                  located in the United States (the "Collateral") in such
                  request, and to perfect and evidence the first priority of all
                  such Security Documents (subject to liens and encumbrances
                  permitted by the terms of such instruments); provided that the
                  Borrower shall not, and shall not permit any of its
                  Subsidiaries to, on or after the Effective Date enter into any
                  amendment of any such contract or agreement, or enter into any
                  other contract or agreement, that in either case would result
                  in any additional such material consent, authorization or
                  approval requirement; and

                                    (ii) deliver to the Administrative Agent,
                  within 30 days of such request for delivery of the Security
                  Documents (or, if a Person other than the Administrative Agent
                  is to act as collateral agent under the Security Documents, if
                  later, within fifteen (15) days of the designation and
                  acceptance by such Person of the collateral agency), evidence
                  acceptable to the Administrative Agent, in its reasonable
                  discretion, indicating that Security Documents covering 80% of
                  the Properties NPV attributable to the Properties located in
                  the United States have been executed, acknowledged, filed,
                  registered and recorded, as the law may require or the Agent
                  may request, in each jurisdiction where so required or
                  requested.

         Borrower further agrees to execute, or cause its Subsidiaries to
         execute, any and all further documents, financing statements,
         agreements and instruments, and take all further actions (including
         filing Uniform Commercial Code financing statements), which may be
         required under applicable law, or which the Administrative Agent may
         reasonably request, in order to effectuate the transactions
         contemplated by this Section 5.1(n) and in order to grant, preserve,
         protect and perfect the validity and first priority of any security
         interests created pursuant to the Security Documents. Borrower will
         also provide and cause its Subsidiaries to provide at their own expense
         to the Administrative Agent such title records or opinions as may be in
         the files of Borrower or its Subsidiaries and operating agreements and
         other instruments and documents relating to the Properties covered by
         the Security




                                       11
   13

         Documents then in the possession of the Borrower or any Subsidiary as
         the Administrative Agent may reasonably request. At such time as no
         Event of Default is continuing and Borrower is satisfying the Debt
         Reduction Requirement, upon request by Borrower to Administrative
         Agent, Administrative Agent shall advise the Collateral Agent, pursuant
         to the terms of the Security Documents, to terminate all Security
         Documents and release all Liens created thereby."

         i.                Subsection 5.2(a)(5) of the Credit Agreement is
                  hereby amended and restated to read in its entirety as
                  follows:

         "        (5)      Debt, other than Debt otherwise permitted by
                           another subparagraph of this Section 5.2(a), which,
                           at the time incurred, is (i) at prevailing market
                           rates of interest and contains covenants and
                           conditions and events of default no more onerous to
                           Designated Entities than the terms of this Agreement;
                           provided, that no Default or Event of Default either
                           (A) exists at the time of the issuance of such Debt
                           and (B) will result from, and be continuing after,
                           the incurrence of such Debt; provided further, that
                           in the case of a Debt Issuance, if Borrower is not
                           satisfying the Debt Reduction Requirement immediately
                           prior to the incurrence of Debt under such Debt
                           Issuance, such Debt shall have a final maturity after
                           August 7, 2002 and be on terms and conditions
                           reasonably acceptable to the Administrative Agent."

         j.                Section 5.2(e) of the Credit Agreement is amended and
                  restated to read in its entirety as follows:

         "        (e)      Limitation on Dividends and Other Restricted
                           Payments. The Borrower will not and will not permit
                           any of its Subsidiaries to pay or declare dividends
                           (other than stock dividends) on, or repurchase, the
                           Borrower's capital stock in excess of $10,000,000 in
                           the aggregate for all such payments and purchases in
                           any Fiscal Year. Borrower will not, and will not
                           permit any Restricted Subsidiary to, make any other
                           Restricted Payments in excess of $5,000,000 in the
                           aggregate for all such Restricted Payments during any
                           Fiscal Year; provided, however, that in the event
                           that any Unrestricted Subsidiary of Borrower is
                           redesignated to be a Restricted Subsidiary of
                           Borrower for purposes of this Agreement, then for
                           purposes of redetermining compliance with this
                           Section, all Restricted Payments made to such
                           Unrestricted Subsidiary shall be deducted from the
                           aggregate total of all Restricted payments made
                           during such Fiscal Year. No Restricted Payment may be
                           made (1) if the Obligations shall exceed the Facility
                           Amount, (2) if any Default or Event of Default shall
                           have occurred and be continuing, or (3) if as a
                           result thereof, any Default or Event of Default shall
                           occur and be continuing."



                                       12
   14

         k.                Subsection 5.2 of the Credit Agreement is amended by
                  adding the following Section 5.2(m).

                  "(m)     "At any time that the Borrower is not satisfying the
                           Debt Reduction Requirement, the Borrower will not,
                           and will not permit any of its Subsidiaries to, sell,
                           transfer, assign or otherwise convey any Property
                           (other than to the Borrower or one of its
                           Subsidiaries) to the extent the aggregate value of
                           non-cash consideration for all sales, transfers,
                           assignments and other conveyances of any Property
                           (other than to the Borrower or one of its
                           Subsidiaries) received on and after February 1, 1999
                           has exceeded or would exceed $25,000,000 in the
                           aggregate. As used herein, the term "non-cash
                           consideration" means any consideration given by or on
                           behalf of the purchaser of Property other than cash,
                           any cash equivalent or any other asset to the extent
                           that at the time in question such other asset has
                           been converted (by collection, sale or otherwise)
                           into cash or any cash equivalent. The value of any
                           such non-cash consideration shall be its fair market
                           value at the time that the contract for such sale,
                           transfer, assignment or other conveyance is entered
                           into, which fair market value shall be determined (i)
                           by reference to market quotations in the case of
                           publicly traded securities or other consideration of
                           the type which is subject to market quotations, (ii)
                           if clause (i) is not applicable, by the value for
                           such consideration set forth in such contract by the
                           parties or (iii) if neither (i) or (ii) is
                           applicable, by a resolution of the board of directors
                           of the Borrower.

         l.                Section 5.3(a) of the Credit Agreement is hereby
                  amended and restated to read in its entirety as follows:

         "        (a)      Senior Leverage Ratio. Borrower's Consolidated Senior
         Leverage Ratio will not (i) as of the last day of the Fiscal Quarters
         ending March 31, 1999, June 30, 1999 and September 30, 1999, be greater
         than 5.75 to 1.0, (ii) as of the last day of the Fiscal Quarters ending
         December 31, 1999 and March 31, 2000, be greater than 4.25 to 1.0, and
         (iii) as of the last day of any Fiscal Quarter ending on or after June
         30, 2000, be greater than 3.50 to 1.00."

         m.                Section 5.3(b) of the Credit Agreement is hereby
                  amended and restated to read in its entirety as follows:

         "        (b)      Total Leverage Ratio. Borrower's Consolidated Total
         Leverage Ratio will not (i) as of the last day of all Fiscal Quarters
         ending prior to June 30, 2000, be greater than 5.75 to 1.00, and (ii)
         as of the last day of any Fiscal Quarter ending on or after June 30,
         2000, be greater than 4.25 to 1.00."

         n.                Section 5.3 of the Credit Agreement is hereby amended
                  by inserting after Section 5.3(b) of the Credit Agreement the
                  following Sections 5.3(c) and 5.3(d):





                                       13
   15

         "        (c)      Minimum Consolidated Tangible Net Worth. Borrower
         will not permit its Consolidated Tangible Net Worth as of the end of
         any Fiscal Quarter, commencing with the Fiscal Quarter ending March 31,
         1999, to be less than (i) $600,000,000 plus (ii) an amount equal to 50%
         of the sum of Borrower's and its Subsidiaries' Consolidated net income
         for each Fiscal Quarter, beginning with the Fiscal Quarter ending March
         31, 1999, during which such Consolidated net income is greater than $0
         plus (iii) an amount equal to 85% of the net cash proceeds received by
         the Borrower and its Subsidiaries from the issuance of any common
         stock, preferred stock or other equity for each Fiscal Quarter,
         beginning with the Fiscal Quarter ending March 31, 1999.

                  (b)      Properties NPV to Total Debt Ratio. Borrower's
         Properties NPV to Total Debt Ratio will not as of the end of any Fiscal
         Quarter ending either June 30th or December 31st, commencing with the
         Fiscal Quarter ending December 31, 1998, be less than 1.25 to 1.00."

         o.                The Credit Agreement is hereby amended by replacing
                  Exhibit I to the Credit Agreement with Exhibit I to this
                  Amendment and Restatement.

         p.                The Credit Agreement is hereby amended by replacing
                  Exhibit J to the Credit Agreement with Exhibit J to this
                  Amendment and Restatement.

         q.                The Credit Agreement is hereby amended by inserting
                  Exhibit Q to this Amendment and Restatement as Exhibit Q to
                  the Credit Agreement following Exhibit P to the Credit
                  Agreement.

         r.                The Credit Agreement is hereby amended by replacing
                  Schedule 3 to the Credit Agreement with Schedule 3 to this
                  Amendment and Restatement.

         s.                The Credit Agreement is hereby amended by replacing
                  Schedule 4 to the Credit Agreement with Schedule 4 to this
                  Amendment and Restatement.

         t.                Schedule 5 to the Credit Agreement is hereby amended
                  by replacing Schedule 5 to the Credit Agreement with Schedule
                  5 to this Amendment and Restatement.

         SECTION 3. Additional Commitments. In the event that Canadian Imperial
Bank of Commerce, The Bank of Nova Scotia, Royal Bank of Canada, The Chase
Manhattan Bank of Canada, Morgan Guaranty Trust Company of New York,
NationsBank, N.A., The Toronto-Dominion Bank, First Union National Bank, and
Wachovia Bank, N.A., or their respective Affiliates shall each agree to increase
their Commitments hereunder by $37,954,477, $37,954,477, $37,954,477,
$33,210,167, $33,210,167, $33,210,167, $33,210,167, $14,232,929, and
$14,232,929, respectively, (such Lenders and their Affiliates herein the
"Increasing Lenders") by advising the Administrative Agent in writing that they
have so agreed to increase their Commitments hereunder and the Canadian Credit
Facility is terminated by the Effective Date of this Amendment and Restatement,
then (i) the Credit Agreement is further amended as provided in this Section 3,
(ii) the Increasing Lenders (but not the other Lenders) shall make a Revolving
Loan




                                       14
   16

Advance on the Effective Date (herein the "Effective Date Revolving Loan
Advance") equal to their respective pro rata share, which Effective Date
Revolving Loan Advance will be in an amount necessary to pay, and will be used
for the purpose of paying, the outstanding Obligations under the Canadian Credit
Facility, (iii) such Effective Date Revolving Loan Advances will be Revolving
Loan Advances for all purposes of the Credit Agreement, (iv) the Increasing
Lenders, the Borrower and the Administrative Agent will cooperate to select
Eurodollar Interest Periods for such Effective Date Revolving Loan Advances that
are similar to the Eurodollar Interest Periods for the Revolving Loan Advances
outstanding under the Credit Agreement on the Effective Date of this Amendment
and (v) the Borrower shall deliver to the Administrative Agent a Guaranty from
(A) Pioneer Natural Resources Canada, Inc., (B) Pioneer Natural Resources
(Argentina) S.A., and (C) Pioneer Natural Resources (Tierra del Fuego) S.A. If
such Increasing Lenders do not each so agree to increase their respective
Commitments hereunder by such date, then the provisions of this Section 3 only
of this Amendment and Restatement shall be of no force or effect.

A.       The definition of Facility Amount in Section 1.1 of the Credit
Agreement is hereby amended and restated to read in its entirety as follows:

         "        "Facility Amount" means the aggregate amount of the
         Commitments (which amount shall be $1,350,169,958 on March 19, 1999),
         as such amount may be reduced from time to time pursuant to the terms
         of this Agreement."

B.       The Credit Agreement is amended by replacing Schedule 1 to the Credit
Agreement with Schedule 1 to this Amendment and Restatement.

C.       In lieu of the definition of "Debt Reduction Requirement" added to the
Credit Agreement pursuant to Section 2.B above, the following definition shall
be added:

         "        "Debt Reduction Requirement" means that all of the following
         requirements shall have occurred (i) the expiration or termination in
         full of the commitments under, and the payment of all amounts under or
         in respect of, the 364 Day Facility, (ii) the reduction of the
         Commitments under this Agreement after February 1, 1999 by an aggregate
         amount of at least $410,000,000 and the payment of all Consolidated
         Total Funded Debt required to be paid as the result of such reduction
         and (iii) the maintenance of the Total Leverage Ratio at less than or
         equal to 4.25 to 1.00 for at least two consecutive Fiscal Quarters ,
         except that solely for purposes of Subsection 2.9(g) hereof,
         satisfaction of the Debt Reduction Requirement shall be determined
         using the following clause (iii) in lieu of the foregoing clause (iii):
         (iii) on the day on which the determination is made and after giving
         pro forma effect to any transaction occurring on such day (including
         repayment of Obligations to be made on such day) the ratio of (a)
         Borrower's then Consolidated Total Funded Debt to (b) Borrower's
         EBITDAX for the four (4) Fiscal Quarters most recently ended prior to
         such day is less than or equal to 4.25 to 1, after adjusting such
         EBITDAX on a pro forma basis for any assets or Property sold or
         acquired after the beginning of such most recently ended four Fiscal
         Quarters as if such assets or Property had been sold or acquired at the
         beginning of such four most recently ended Fiscal Quarters; provided
         that for purposes of the calculation in this clause (iii) for purposes
         solely of Section 2.9(g) hereof, (1) EBITDAX for the four Fiscal
         Quarters ending December 31, 1998 shall be




                                       15
   17

         deemed to be four times the EBITDAX for the Fiscal Quarter ending on
         such date after adjusting such EBITDAX on a pro forma basis for any
         assets or Property sold or acquired after the beginning of such Fiscal
         Quarter as if such assets or Property had been sold or acquired at the
         beginning of such Fiscal Quarter, (2) EBITDAX for the four Fiscal
         Quarters ending March 31, 1999 shall be deemed to be two times the
         EBITDAX for the semi-annual period ending on such date after adjusting
         such EBITDAX on a pro forma basis for any assets or Property sold or
         acquired after the beginning of such semi-annual period ending on such
         date as if such assets or Property had been sold or acquired at the
         beginning of such semi-annual period ending on such date and (3)
         EBITDAX for the four Fiscal Quarters ending June 30, 1999 shall be
         deemed to be the product of 4/3rds times EBITDAX for the three Fiscal
         Quarters ending on such date after adjusting such EBITDAX on a pro
         forma basis for any assets or Property sold or acquired after the
         beginning of such three Fiscal Quarters as if such assets or Property
         had been sold or acquired at the beginning of such three Fiscal
         Quarters."

D.       In lieu of Subsection 2.9(h) added to the Credit Agreement pursuant to
Section 2.E above, the following Subsection 2.9(h) shall be added:

         "        (h)      Notwithstanding any other provision of this
         Agreement, if during the period commencing March 19, 1999 and ending
         December 31, 1999 the aggregate reductions in Commitments pursuant to
         the foregoing subsection of this Section 2.9 is less than $410,000,000,
         on December 31, 1999 on such date the Commitments shall be
         automatically reduced by the remainder of (i) $410,000,000 minus (ii)
         the total of all reductions in the Commitment pursuant to the foregoing
         subsections of this Section 2.9 on or prior to December 31, 1999, and
         Borrower shall make a mandatory prepayment on December 31, 1999 in an
         amount sufficient to cause the sum of (i) all Lenders' Revolving Loan
         Advances (including any Revolving Loan Advances to be made but not yet
         made pursuant to a Request for Advance) outstanding at such time plus
         (ii) the LC Obligations of all Lenders at such time plus (iii) all
         Swing Line Advances to Borrower plus (iv) all Lenders' Competitive Bid
         Advances outstanding at such time not to exceed the Total Commitments
         after giving effect to such reduction."

E.       In lieu of the Subsection 5.1(n) added to the Credit Agreement pursuant
to Section 2H above, the following subsection shall be added:

         "        (n)      Springing Lien. In the event that (i) any Event of
         Default has occurred and is continuing or (ii) at any time after August
         3, 1999 the sum of (A) aggregate Commitments under this Agreement plus
         (B) the aggregate "Commitments" under the 364 Day Credit Facility,
         exceeds $1,050,000,000, then, without affecting in any way any other
         rights of the Lenders hereunder, the Administrative Agent, at the
         direction of the Required Lenders, may request that the Borrower, and
         the Borrower agrees to:

                                    (i) duly execute and deliver to the
                  Administrative Agent (or such other Person designated by the
                  Administrative Agent) the Security Documents and cause each
                  such Security Document to be filed, registered and




                                       16
   18

                  recorded, as the law may require or the Administrative Agent
                  may request, in each jurisdiction where so required or
                  requested, and deliver to the Administrative Agent an
                  acknowledgment copy, or other evidence satisfactory to it, of
                  each such filing, registration and recordation, in order to
                  mortgage, assign, grant a security interest in and pledge to
                  the Administrative Agent (or such other Person designated by
                  the Administrative Agent), acting on behalf of the Lenders,
                  all of the Borrower's and the Restricted Subsidiaries' right,
                  title and interest in and to the Properties located in the
                  United States, and the proceeds thereof, having a Properties
                  NPV, as of the date of the most recent Engineering Report, of
                  80% of the aggregate Properties NPV attributable to Properties
                  located in the United States (the "Collateral") in such
                  request, and to perfect and evidence the first priority of all
                  such Security Documents (subject to liens and encumbrances
                  permitted by the terms of such instruments); provided that the
                  Borrower shall not, and shall not permit any of its
                  Subsidiaries to, on or after the Effective Date enter into any
                  amendment of any such contract or agreement, or enter into any
                  other contract or agreement, that in either case would result
                  in any additional such material consent, authorization or
                  approval requirement; and

                                    (ii) deliver to the Administrative Agent,
                  within 30 days of such request for delivery of the Security
                  Documents (or, if a Person other than the Administrative Agent
                  is to act as collateral agent under the Security Documents, if
                  later, within fifteen (15) days of the designation and
                  acceptance by such Person of the collateral agency), evidence
                  acceptable to the Administrative Agent, in its reasonable
                  discretion, indicating that Security Documents covering 80% of
                  the Properties NPV attributable to the Properties located in
                  the United States have been executed, acknowledged, filed,
                  registered and recorded, as the law may require or the Agent
                  may request, in each jurisdiction where so required or
                  requested.

         Borrower further agrees to execute, or cause its Subsidiaries to
         execute, any and all further documents, financing statements,
         agreements and instruments, and take all further actions (including
         filing Uniform Commercial Code financing statements), which may be
         required under applicable law, or which the Administrative Agent may
         reasonably request, in order to effectuate the transactions
         contemplated by this Section 5.1(n) and in order to grant, preserve,
         protect and perfect the validity and first priority of any security
         interests created pursuant to the Security Documents. Borrower will
         also provide and cause its Subsidiaries to provide at their own expense
         to the Administrative Agent such title records or opinions as may be in
         the files of Borrower or its Subsidiaries and operating agreements and
         other instruments and documents relating to the Properties covered by
         the Security Documents then in the possession of the Borrower or any
         Subsidiary as the Administrative Agent may reasonably request. At such
         time as no Event of Default is continuing and Borrower is satisfying
         the Debt Reduction Requirement, upon request by Borrower to
         Administrative Agent, Administrative Agent shall advise the Collateral
         Agent, pursuant to the terms of the Security Documents, to terminate
         all Security Documents and release all Liens created thereby."





                                       17
   19

F.       Subsection 2.9(j) added to the Credit Agreement pursuant to Section 2E
above is deleted from the Credit Agreement in its entirety.

         SECTION 4. Representations and Warranties. To confirm each Lender's
understanding concerning Borrower and its businesses, properties and
obligations, and to induce the Managing Agents, the Collateral Agent, the
Co-Agents and each Lender to enter into this Amendment and Restatement, the
Borrower hereby reaffirms to the Managing Agents, the Collateral Agent, the
Co-Agents and each Lender that, as of the date hereof, its representations and
warranties contained in Section 4.1 of the Credit Agreement (as amended by this
Amendment and Restatement) and in the other Loan Documents to which it is a
party (except to the extent such representations and warranties relate solely to
an earlier date) are true and correct and additionally represents and warrants
as follows:

A.       The execution and delivery of this Amendment and Restatement and the
         performance by the Borrower and the Restricted Subsidiaries of their
         respective obligations under this Amendment and Restatement, the Credit
         Agreement and the other Loan Documents, as amended hereby, are within
         the Borrower's or such Restricted Subsidiaries' corporate or
         partnership powers, have been duly authorized by all necessary
         corporate or partnership action, have received all necessary
         governmental approval (if any shall be required), and do not and will
         not contravene or conflict with any provision of law or of the
         Borrower's or such Restricted Subsidiaries' charter or bylaws or
         partnership agreement or of any contractual restriction, law or
         governmental regulation or court decree or order binding on or
         affecting the Borrower or such Restricted Subsidiary.

B.       This Amendment and Restatement and the Credit Agreement as amended
         hereby are, and the other Loan Documents when duly executed and
         delivered will be, legal, valid and binding obligations of the Borrower
         and each Restricted Subsidiary which is a party hereto or thereto,
         enforceable in accordance with their terms except as such enforcement
         may be limited by bankruptcy, insolvency or similar laws of general
         application relating to the enforcement of creditors' rights generally
         and by general principles of equity.

         SECTION 5. Conditions to Effectiveness. The effectiveness of this
Amendment and Restatement is conditioned upon receipt by the Administrative
Agent of all the following documents and items, each in form and substance
reasonably satisfactory to the Administrative Agent:

         A.       this Amendment and Restatement executed by the Borrower and
                  the Required Lenders.

         B.       Delivery of the Initial Engineering Report.

         C.       Payment to Administrative Agent for the account of each Lender
                  which executes and delivers a copy of this Amendment and
                  Restatement to the Administrative Agent on or before March 19,
                  1999, of a non-refundable amendment fee payable to each such
                  Lender determined by applying the Amendment Fee Rate to such
                  Lender's Percentage Share of the Facility Amount as of the
                  date of this Amendment and Restatement.

         D.       Payment to Administrative Agent for the account of NationsBanc
                  Montgomery Securities LLC, as sole arranger and book manager,
                  a non-refundable advisory fee in the amount set



                                       18
   20

                  forth in that certain Commitment/Fee Letter, dated February 4,
                  1999 between NationsBanc Montgomery Securities LLC and the
                  Borrower.

         E.       Delivery of favorable opinions of counsel for Borrower and the
                  Restricted Subsidiaries, in form and substance acceptable to
                  the Administrative Agent, in its sole discretion.

         F.       Unless the Canadian Credit Facility shall have terminated, the
                  Required Lenders (as defined in the Canadian Credit Facility)
                  shall have consented to this Amendment, it being agreed by the
                  parties hereto that such consent may require reductions in
                  commitments and paydowns under the Canadian Credit Facility
                  similar to the reductions and paydowns required by Sections
                  2.9(d), (e) and (f) added by Section 2E above and to the
                  extent permitted by Section 2.9(j) added by Section 2E above.

         H.       Such other documents or items that the Administrative Agent
                  may reasonably request.

         SECTION 6. Reaffirmation of Credit Agreement. This Amendment and
Restatement constitutes a "Loan Document" as defined in the Credit Agreement and
shall be deemed to be an amendment and restatement of the Credit Agreement, and
the Credit Agreement, as amended and restated hereby, is hereby ratified,
approved and confirmed in each and every respect. All references to the Credit
Agreement or the Credit Facility Agreement in any other document, instrument,
agreement or writing shall hereafter be deemed to refer to this Amendment and
Restatement.

         SECTION 7. Parties in Interest. All grants, covenants and agreements
contained in this Amendment and Restatement shall bind and inure to the benefit
of the parties thereto and their respective successors and assigns; provided,
however, that no Restricted Subsidiary may assign or transfer any of its rights
or delegate any of its duties or obligations under this Amendment and
Restatement or any Loan Document without the prior written consent of all
Lenders.

         SECTION 8. Counterparts. This Amendment and Restatement may be
separately executed in any number of counterparts and by different parties
hereto in separate counterparts, each of which when so executed shall be deemed
to constitute one and the same Amendment and Restatement.

         SECTION 9. GOVERNING LAW. THIS AMENDMENT AND RESTATEMENT AND THE OTHER
LOAN DOCUMENTS SHALL BE DEEMED CONTRACTS AND INSTRUMENTS MADE UNDER THE LAWS OF
THE STATE OF TEXAS AND SHALL BE CONSTRUED AND ENFORCED IN ACCORDANCE WITH AND
GOVERNED BY THE LAWS OF THE STATE OF TEXAS AND THE LAWS OF THE UNITED STATES OF
AMERICA, WITHOUT REGARD TO PRINCIPLES OF CONFLICTS OF LAW. CHAPTER 15 OF TEXAS
REVISED CIVIL STATUTES ANNOTATED ARTICLE 5069 (WHICH REGULATES CERTAIN REVOLVING
CREDIT LOAN ACCOUNTS AND REVOLVING TRI-PARTY ACCOUNTS) DOES NOT APPLY TO THIS
AMENDMENT AND RESTATEMENT OR TO THE NOTES.

         SECTION 10. Severability. If any term or provision of this Amendment
and Restatement or of any Loan Document shall be determined to be illegal or
unenforceable in any jurisdiction, such term or




                                       19
   21

provision shall, as to such jurisdiction, be illegal or unenforceable, without
affecting the remaining terms or provisions in that jurisdiction or the legality
or enforceability of such terms or provisions in any other jurisdiction.

         SECTION 11. WAIVER OF JURY TRIAL, PUNITIVE DAMAGES. EACH OF THE
BORROWER, AGENTS AND LENDERS HEREBY (I) IRREVOCABLY WAIVES, TO THE MAXIMUM
EXTENT NOT PROHIBITED BY LAW, ANY RIGHT IT MAY HAVE TO A TRIAL BY JURY IN
RESPECT OF ANY LITIGATION, DIRECTLY OR INDIRECTLY, AT ANY TIME ARISING OUT OF,
UNDER OR IN CONNECTION WITH THE LOAN DOCUMENTS OR ANY TRANSACTION CONTEMPLATED
THEREBY OR ASSOCIATED THEREWITH, BEFORE OR AFTER MATURITY; (II) IRREVOCABLY
WAIVES, TO THE MAXIMUM EXTENT NOT PROHIBITED BY LAW, ANY RIGHT IT MAY HAVE TO
CLAIM OR RECOVER IN ANY SUCH LITIGATION ANY EXEMPLARY, PUNITIVE OR CONSEQUENTIAL
DAMAGES; (III) CERTIFIES THAT NO PARTY HERETO NOR ANY REPRESENTATIVE OR AGENT OR
COUNSEL FOR ANY PARTY HERETO HAS REPRESENTED, EXPRESSLY OR OTHERWISE, OR IMPLIED
THAT SUCH PARTY WOULD NOT, IN THE EVENT OF LITIGATION, SEEK TO ENFORCE THE
FOREGOING WAIVERS; AND (IV) ACKNOWLEDGES THAT IT HAS BEEN INDUCED TO ENTER INTO
THIS AMENDMENT AND RESTATEMENT, THE OTHER LOAN DOCUMENTS AND THE TRANSACTIONS
CONTEMPLATED HEREBY AND THEREBY BY, AMONG OTHER THINGS, THE MUTUAL WAIVERS AND
CERTIFICATIONS CONTAINED IN THIS SECTION.

         SECTION 12. FORUM SELECTION AND CONSENT TO JURISDICTION. ANY LITIGATION
BASED HEREON, OR ARISING OUT OF, UNDER, OR IN CONNECTION WITH, THIS AMENDMENT
AND RESTATEMENT OR ANY OTHER LOAN DOCUMENT, OR ANY COURSE OF CONDUCT, COURSE OF
DEALING, STATEMENTS (WHETHER VERBAL OR WRITTEN) OR ACTIONS OF THE AGENTS, THE
LENDERS OR THE BORROWER SHALL BE BROUGHT AND MAINTAINED EXCLUSIVELY IN THE
COURTS OF THE STATE OF TEXAS OR IN THE UNITED STATES DISTRICT COURT FOR THE
NORTHERN DISTRICT OF TEXAS; PROVIDED, HOWEVER, THAT ANY SUIT SEEKING ENFORCEMENT
AGAINST ANY COLLATERAL OR OTHER PROPERTY MAY BE BROUGHT, AT THE COLLATERAL
AGENT'S OPTION, IN THE COURTS OF ANY JURISDICTION WHERE SUCH COLLATERAL OR OTHER
PROPERTY MAY BE FOUND. BORROWER HEREBY EXPRESSLY AND IRREVOCABLY SUBMITS TO THE
JURISDICTION OF THE COURTS OF THE STATE OF TEXAS AND THE UNITED STATES DISTRICT
COURT FOR THE NORTHERN DISTRICT OF TEXAS FOR THE PURPOSE OF ANY SUCH LITIGATION
AS SET FORTH ABOVE AND IRREVOCABLY AGREES TO BE BOUND BY ANY JUDGMENT RENDERED
THEREBY IN CONNECTION WITH SUCH LITIGATION. BORROWER FURTHER IRREVOCABLY
CONSENTS TO THE SERVICE OF PROCESS BY REGISTERED MAIL, POSTAGE PREPAID, OR BY
PERSONAL SERVICE WITHIN OR WITHOUT THE STATE OF TEXAS. FOR THE PURPOSE OF ANY
ACTION OR PROCEEDING INSTITUTED IN THE FEDERAL OR STATE COURTS OF TEXAS, EACH
RESTRICTED SUBSIDIARY OF THE BORROWER HEREBY IRREVOCABLY DESIGNATES BORROWER
WITH OFFICES ON THE DATE HEREOF AT 1400 WILLIAMS




                                       20
   22

SQUARE WEST, 5205 NORTH O'CONNOR BOULEVARD, IRVING, TEXAS 75039 TO RECEIVE FOR
AND ON BEHALF OF SUCH RESTRICTED SUBSIDIARY, SERVICE OF PROCESS IN TEXAS.
BORROWER HEREBY EXPRESSLY AND IRREVOCABLY WAIVES, TO THE FULLEST EXTENT
PERMITTED BY LAW, ANY OBJECTION WHICH IT MAY HAVE OR HEREAFTER MAY HAVE TO THE
LAYING OF VENUE OF ANY SUCH LITIGATION BROUGHT IN ANY SUCH COURT REFERRED TO
ABOVE AND ANY CLAIM THAT ANY SUCH LITIGATION HAS BEEN BROUGHT IN AN INCONVENIENT
FORUM. TO THE EXTENT THAT THE BORROWER HAS OR HEREAFTER MAY ACQUIRE ANY IMMUNITY
FROM JURISDICTION OF ANY COURT OR FROM ANY LEGAL PROCESS (WHETHER THROUGH
SERVICE OR NOTICE, ATTACHMENT PRIOR TO JUDGMENT, ATTACHMENT IN AID OF EXECUTION
OR OTHERWISE) WITH RESPECT TO ITSELF OR ITS PROPERTY, BORROWER HEREBY
IRREVOCABLY WAIVES SUCH IMMUNITY IN RESPECT OF ITS OBLIGATIONS UNDER THIS
AMENDMENT AND RESTATEMENT AND THE OTHER LOAN DOCUMENTS.

         SECTION 13. Effectiveness. This Amendment and Restatement shall become
effective as of March 19, 1999 ("Effective Date"), when counterparts hereof
executed on behalf of the Borrower and the Required Lenders (or notice thereof
satisfactory to the Agent) shall have been received by the Administrative Agent,
and all conditions set forth in Section 4 hereof have been fulfilled.

         SECTION 14. Entire Agreement. THIS WRITTEN AMENDMENT AND RESTATEMENT
AND THE OTHER LOAN DOCUMENTS REPRESENT THE FINAL AGREEMENT BETWEEN THE PARTIES
AND MAY NOT BE CONTRADICTED BY EVIDENCE OF PRIOR, CONTEMPORANEOUS, OR SUBSEQUENT
ORAL AGREEMENTS OF THE PARTIES.

         THERE ARE NO UNWRITTEN ORAL AGREEMENTS BETWEEN THE PARTIES.

                    [SIGNATURES BEGIN ON THE FOLLOWING PAGE]




                                       21
   23


         IN WITNESS WHEREOF, this Amendment and Restatement is executed as of
the date first written above.

                                   BORROWER:

                                   PIONEER NATURAL RESOURCES
                                   COMPANY

                                   By:
                                      -----------------------------------------
                                   Name:    M. Garrett Smith
                                   Title:   Executive Vice President and Chief
                                            Financial Officer





                                      S-1
   24





                                  LENDERS:

                                  NATIONSBANK, N.A., successor-by-merger
                                  to NationsBank of Texas, N.A., individually
                                  and as Administrative Agent and as Collateral
                                  Agent

                                  By:
                                     -------------------------------------------
                                  Name:
                                  Title:






                                      S-2
   25






                               CIBC INC., individually and as
                               Documentation Agent


                               By:
                                  -------------------------------------------
                               Name:
                               Title:






                                      S-3
   26






                               MORGAN GUARANTY TRUST
                               COMPANY OF NEW YORK, individually
                               and as Documentation Agent


                               By:
                                  -------------------------------------------
                               Name:
                               Title:











                                      S-4
   27

                               CHASE BANK OF TEXAS, NATIONAL
                               ASSOCIATION, as successor-in-interest to
                               The Chase Manhattan Bank, individually and as
                               Syndication Agent

                               By:
                                  -------------------------------------------
                               Name:
                               Title:









                                      S-5
   28





                   [SIGNATURE PAGE S-6 INTENTIONALLY OMITTED]














                                      S-6
   29






                               THE BANK OF NEW YORK, individually
                               and as Co-Agent

                               By:
                                  -------------------------------------------
                               Name:
                               Title:




                                      S-7
   30






                               THE BANK OF NOVA SCOTIA,
                               individually and as Co-Agent


                               By:
                                  -------------------------------------------
                               Name:
                               Title:





                                      S-8
   31





                               ROYAL BANK OF CANADA, individually
                               and as Co-Agent



                               By:
                                  -------------------------------------------
                               Name:
                               Title:











                                      S-9
   32



                               UNION BANK OF CALIFORNIA, N.A.,
                               individually and as Co-Agent



                               By:
                                  -------------------------------------------
                               Name:
                               Title:







                                      S-10
   33





                               WELLS FARGO BANK, N.A.,
                               individually and as Co-Agent


                               By:
                                  -------------------------------------------
                               Name:
                               Title:







                                      S-11
   34





                               BANK ONE, TEXAS, N.A., individually



                               By:
                                  -------------------------------------------
                               Name:
                               Title:






                                      S-12
   35






                               DEN NORSKE BANK ASA, individually and
                               as Lead Manager


                               By:
                                  -------------------------------------------
                               Name:
                               Title:


                               By:
                                  -------------------------------------------
                               Name:
                               Title:







                                      S-13
   36





                               PARIBAS, individually and as Lead Manager




                               By:
                                  -------------------------------------------
                               Name:
                               Title:


                               By:
                                  -------------------------------------------
                               Name:
                               Title:






                                      S-14
   37





                               FIRST UNION NATIONAL BANK,
                               individually and as Lead Manager




                               By:
                                  -------------------------------------------
                               Name:
                               Title:







                                      S-15
   38





                               BANKERS TRUST COMPANY, as a Lender



                               By:
                                  -------------------------------------------
                               Name:
                               Title:







                                      S-16
   39





                               CREDIT AGRICOLE INDOSUEZ, as a
                               Lender



                               By:
                                  -------------------------------------------
                               Name:
                               Title:


                               By:
                                  -------------------------------------------
                               Name:
                               Title:






                                      S-17
   40






                               NATEXIS BANQUE, as a Lender



                               By:
                                  -------------------------------------------
                               Name:
                               Title:


                               By:
                                  -------------------------------------------
                               Name:
                               Title:








                                      S-18
   41





                               TORONTO DOMINION (TEXAS), INC., as
                               a Lender



                               By:
                                  -------------------------------------------
                               Name:
                               Title:





                                      S-19
   42





                               THE TOYO TRUST & BANKING CO.,
                               LTD., as a Lender



                               By:
                                  -------------------------------------------
                               Name:
                               Title:







                                      S-20
   43





                               WACHOVIA BANK, N.A., as a Lender


                               By:
                                  -------------------------------------------
                               Name:
                               Title:







                                      S-21
   44





                               THE DAI-ICHI KANGYO BANK, LTD.,
                               NEW YORK BRANCH, as a Lender





                               By:
                                  -------------------------------------------
                               Name:
                               Title:







                                      S-22
   45





                               THE SANWA BANK, LIMITED, as a
                               Lender



                               By:
                                  -------------------------------------------
                               Name:
                               Title:









                                      S-23
   46





                               KBC BANK N.V., as a Lender




                               By:
                                  -------------------------------------------
                               Name:
                               Title:


                               By:
                                  -------------------------------------------
                               Name:
                               Title:



                                      S-24


   47





                                    Exhibit I

               Organization Chart of Borrower and its Subsidiaries









                               Exhibit I - Page 1

   48




                                    Exhibit J

                    Form of Designated Officer's Certificate

         Reference is made to (i) the Primary Credit Facility pursuant to that
certain Second Amended and Restated Credit Facility Agreement dated as of March
19, 1999, by and among Borrower, NationsBank, N.A., as Administrative Agent,
CIBC Inc., as Documentation Agent, Morgan Guaranty Trust Company of New York, as
Documentation Agent, Chase Bank of Texas, National Association, as
successor-in-interest to The Chase Manhattan Bank, as Syndication Agent, the
Co-Agents party thereto, and the Lenders from time to time parties thereto (the
"Primary Credit Agreement") and (ii) the 364 Day Credit Facility pursuant to
that certain Second Amended and Restated Credit Facility Agreement dated as of
March 19, 1999, by and among Borrower, NationsBank, N.A., as Administrative
Agent, CIBC Inc., as Documentation Agent, Morgan Guaranty Trust Company of New
York, as Documentation Agent, Chase Bank of Texas, National Association, as
successor-in-interest to The Chase Manhattan Bank, as Syndication Agent, the Co-
Agents party thereto, and the Lenders from time to time parties thereto (the
"364 Day Credit Agreement" and, together with the Primary Credit Facility, the
"Credit Agreements"). Terms which are defined in the Credit Agreements and which
are used but not defined herein are used herein with the meanings given them in
the Credit Agreements.

         This Certificate is furnished pursuant to Section 5.1(b)(2) of the
Credit Agreements. Together herewith the Borrower is furnishing to Managing
Agents, the Co-Agents and each Lender the Borrower's [FINANCIAL STATEMENTS] (the
"Financial Statements") as of (the "Reporting Date"). The Borrower hereby
represents, warrants, and acknowledges to Agents and each Lender that:

         (a)      the Designated Officer of the Borrower signing this instrument
                  is a duly elected, qualified and acting officer of the
                  Borrower;

         (b)      the Financial Statements are accurate and complete and satisfy
                  the requirements of the Credit Agreements;

         (c)      attached as Schedule I hereto is a schedule of calculations
                  showing compliance (or noncompliance, as the case may be) as
                  of the Reporting Date with the requirements of Sections 5.2(e)
                  and 5.3 of the Credit Agreements; and

         (d)      on the Reporting Date, the Borrower was, and on the date
                  hereof the Borrower is, in full compliance with the disclosure
                  requirements of Section 5.1(d) of the Credit Agreements, and
                  no Default otherwise existed on the Reporting Date or
                  otherwise exists on the date of this Certificate [except for
                  Default(s) under Section(s)________ of the Credit Agreements,
                  which [is/are] more fully described on a schedule attached
                  hereto].






                                Exhibit J - Page 1
   49





         The Designated Officer of the Borrower signing this instrument hereby
certifies that he has reviewed the Loan Documents and the Financial Statements
and has otherwise undertaken such inquiry as is in his opinion necessary to
enable him to express an informed opinion with respect to the above
representations, warranties and acknowledgments of the Borrower and, to the best
of his knowledge, such representations, warranties, and acknowledgments are
true, correct and complete.

                               PIONEER NATURAL RESOURCES
                               COMPANY


                               By:
                                  -------------------------------------------
                               Name:
                               Title:

                               Date:
                                    -----------------------------------------







                               Exhibit J - Page 2
   50






                                   Schedule I

================================================================================

COMPLIANCE WITH COVENANTS AS OF              . ($ in 000's)
                                -------------
================================================================================

A.     SENIOR LEVERAGE RATIO                                           =========

                      Minimum ratio allowed         : 1
                                                 =========
B.     TOTAL LEVERAGE RATIO                                            =========

                      Minimum ratio allowed         : 1
                                                 =========
C.     CONSOLIDATED TANGIBLE NET WORTH                                 =========

                      Minimum allowed

[D.    PROPERTIES NPV TO TOTAL DEBT RATIO                              =========

                      Minimum ratio allowed         : 1    ](1)
                                                 =========
E.     RESTRICTED PAYMENTS DURING PRECEDING FISCAL QUARTER             =========

================================================================================

COMPUTATION OF FINANCIAL REQUIREMENTS AND RATIOS AS OF
                                                       ----------
================================================================================

A.       SENIOR LEVERAGE RATIO (Section 5.3(a)) ($ in 000's)

               (i)    SENIOR DEBT:

                      (a)       Consolidated Total Debt:  $
                                                           ----------
                      (b)       Less Subordinated Debt:         $
                                                                 ----------
                      SENIOR DEBT:                                    $
                                                                       ---------

- -------------------
  (1)  Properties NPV to Total Debt Ratio only calculated for Fiscal Quarters
       ending June 30th and December 31st of each Fiscal Year



                               Exhibit J - Page 3
   51



            (ii)  EBITDAX                                               $
                                                                        ========
       SENIOR LEVERAGE RATIO ((i)(ii))
                                                                        ========
                  Minimum ratio allowed          :1
                                             =========

B.     TOTAL LEVERAGE RATIO (Section 5.3(B)) ($ in 000's)

            (i)   CONSOLIDATED TOTAL DEBT :                             $
                                                                        --------
            (ii)  EBITDAX                                               $
                                                                        ========
       TOTAL LEVERAGE RATIO ((i)(ii))
                                                                        ========
                  Minimum ratio allowed          :1
                                             =========

C.     CONSOLIDATED TANGIBLE NET WORTH (Section 5.3(c)) ($ in 000's)

       CONSOLIDATED TANGIBLE NET WORTH

            (i)   Consolidated shareholder's equity of
                  Borrower and its Subsidiaries                         $
                                                                        --------
            (ii)  Less Consolidated intangible assets of
                  Borrower and its Subsidiaries                         $
                                                                        --------
            (iii) Plus aggregate amount of any non-cash write downs,
                  on a consolidated basis, by Borrower and its
                  Subsidiaries                                          $

                                                                        --------
            (iv)  Plus 50% of the sum of Borrower's and its Subsidiaries
                  Consolidated net income for each Fiscal Quarter beginning
                  with the fiscal quarter ending March 31, 1999         $
                                                                        --------

            (iv)  Plus 85% of the net cash proceeds received by the Borrower
                  and its Subsidiaries from the issuance of any common
                  stock, preferred stock or other equity for each Fiscal
                  Quarter beginning  with the Fiscal Quarter ending
                  March 31, 1999.                                       $
                                                                        --------

                  CONSOLIDATED TANGIBLE NET WORTH                       $
                                                                        ========
                  Minimum allowed
                                                  ========
[D.    PROPERTIES NPV TO TOTAL DEBT RATIO                               ========

                  (i)      PROPERTIES NPV                               $
                                                                        --------




                               Exhibit J - Page 4
   52



                  (ii)     TOTAL DEBT                                   $
                                                                         =======

         PROPERTIES TO TOTAL DEBT RATIO ((i)(ii))
                                                                         =======
                           Minimum ratio allowed      :1     ](2)
                                                   =========








- -------------------------
        (2)       Properties NPV to Total Debt Ratio only calculated for Fiscal
                  Quarters ending June 30th and December 31st of each Fiscal
                  Year






                               Exhibit J - Page 5
   53





                                    Exhibit Q

                                    [Form of]

                  MORTGAGE, DEED OF TRUST, ASSIGNMENT, SECURITY
                        AGREEMENT AND FINANCING STATEMENT

                                      FROM

                       ---------------------------------
                          (Taxpayer I.D. No._________)

                                       TO

                         ____________________, Trustee

                                       AND

                         ____________________, Trustee

                                       AND

                        ______________________________,
                               as Collateral Agent
                           (Taxpayer I.D. No.________)


                       Dated as of ________________, 1999

- --------------------------------------------------------------------------------

"THIS INSTRUMENT CONTAINS AFTER-ACQUIRED PROPERTY PROVISIONS."

"THIS INSTRUMENT SECURES PAYMENT OF FUTURE ADVANCES."

"THE OIL AND GAS INTERESTS INCLUDED IN THE MORTGAGED PROPERTY WILL BE FINANCED
AT THE WELLHEADS OF THE WELLS LOCATED ON THE PROPERTIES DESCRIBED IN EXHIBIT A
HERETO, AND THIS FINANCING STATEMENT IS TO BE FILED FOR RECORD, AMONG OTHER
PLACES, IN THE REAL ESTATE RECORDS."

"THOSE PORTIONS OF THE MORTGAGED PROPERTY WHICH ARE MINERALS OR OTHER SUBSTANCES
OF VALUE WHICH MAY BE EXTRACTED FROM THE EARTH (INCLUDING, WITHOUT LIMITATION,
OIL AND GAS), AND THE ACCOUNTS RELATING THERETO, WILL BE FINANCED AT THE
WELLHEADS OF THE WELLS LOCATED ON THE PROPERTIES



                               Exhibit Q - Page 1
   54


DESCRIBED IN EXHIBIT A HERETO, AND THIS FINANCING STATEMENT IS TO BE FILED FOR
RECORD, AMONG OTHER PLACES, IN THE REAL ESTATE RECORDS."

"THE MORTGAGOR HAS AN INTEREST OF RECORD IN THE REAL ESTATE CONCERNED,
WHICH IS DESCRIBED IN EXHIBIT A HERETO."

"THIS INSTRUMENT IS A LINE OF CREDIT MORTGAGE."

"SOME OF THE PERSONAL PROPERTY CONSTITUTING A PORTION OF THE MORTGAGED PROPERTY
IS OR IS TO BE AFFIXED TO THE PROPERTIES DESCRIBED IN EXHIBIT A HERETO, AND THIS
FINANCING STATEMENT IS TO BE FILED FOR RECORD, AMONG OTHER PLACES, IN THE REAL
ESTATE RECORDS."

"A POWER OF SALE HAS BEEN GRANTED IN THIS MORTGAGE.  A POWER OF SALE MAY
ALLOW THE MORTGAGEE TO TAKE THE MORTGAGED PROPERTY AND SELL IT WITHOUT
GOING TO COURT IN A FORECLOSURE ACTION UPON DEFAULT BY THE MORTGAGOR
UNDER THIS MORTGAGE."

"THE AMOUNT INVOLVED IS $200 OR MORE."

THIS INSTRUMENT WAS PREPARED BY AND
WHEN RECORDED AND/OR FILED
RETURN TO:

Francis R. Bradley, III, Esq.
Mayer, Brown & Platt
700 Louisiana, Suite 3600
Houston, TX  77002






                               Exhibit Q - Page 2
   55





                  MORTGAGE, DEED OF TRUST, ASSIGNMENT, SECURITY
                        AGREEMENT AND FINANCING STATEMENT

         THIS MORTGAGE, DEED OF TRUST, ASSIGNMENT, SECURITY AGREEMENT AND
FINANCING STATEMENT, dated as of , 1999, is from
_______________________________, a _________________ (herein called the
"Mortgagor"), to_________________________________ ____________________________
and __________________________, of _____________, _________________, as Trustees
(herein collectively called the "Trustees"), and ___________________, a
______________, having is principal place of business at ________________,
_____________ _____ as collateral agent (herein, in such capacity, together with
any successor(s) thereto in such capacity, called the "Collateral Agent") for
the Lenders and the Noteholders.

         1. For all purposes of this instrument, unless the context otherwise
requires:

                  A. "Borrower" shall mean the "Borrower" as defined in the
Primary Credit Agreement (hereinafter defined) [and the 364-Day Credit Agreement
(hereinafter defined)].

                  B. "Credit Agreement Notes" shall mean the "Notes" as defined
in the Primary Credit Agreement [and the "Notes" as defined in the 364-Day
Credit Agreement].

                  C. "Encumbrance" shall mean any irregularity in title, lien,
security interest, pledge, charge, encumbrance, claim, burden or defect.

                  D. "Hydrocarbons" shall mean oil, gas and other liquid or
gaseous hydrocarbons.

                  E. "Indenture Notes" shall mean each of the following: (i)
Borrower's $150,000,000 8 7/8% Senior Notes due 2005, (ii) Borrower's
$150,000,000 8 1/4% Senior Notes due 2007, (iii) Borrower's $350,000,000 6.50%
Senior Notes due 2008, (iv) Borrower's $250,000,000 7.20% Senior Notes due 2028,
and (v) and other publicly tradeable notes, bonds or debentures outstanding as
of February 1, 1999, which notes, bonds or debentures by their terms require
that they be secured equally and ratably with this instrument.

                  F. "Indenture Trustees" means each of the trustees from time
to time appointed pursuant to the terms of any indenture or similar agreement
governing any of the Indenture Notes.

                  G. "lands described in Exhibit A" shall include any lands
which are either described in Exhibit A or the description of which is
incorporated in Exhibit A by reference to another instrument or document, and
shall also include any lands now or hereafter unitized or pooled with lands
which are either described in Exhibit A or the description of which is
incorporated in Exhibit A by reference.

                  H. "Lenders" shall mean the "Lenders" as defined in the
Primary Credit Agreement [and the "Lenders" as defined in the 364-Day Credit
Agreement].

                  I. "Mortgaged Property" shall mean the properties, rights and
interests hereinafter described and defined as the Mortgaged Property.





                               Exhibit Q - Page 3
   56




                  J. "Noteholders" means any owner or holder of any of the
Indenture Notes from time to time.

                  K. "oil and gas leases" shall include oil, gas and mineral
leases, subleases and assignments thereof, operating rights, and shall also
include subleases and assignments of operating rights.

                  L. "Operating Equipment" shall mean all surface or subsurface
machinery, goods, equipment, fixtures, inventory, facilities, supplies or other
property of whatsoever kind or nature (excluding drilling rigs, trucks,
automotive equipment or other property taken to the premises to drill a well or
for other similar temporary uses) now or hereafter located on or under any of
the lands described in Exhibit A which are useful for the production, gathering,
treatment, processing, storage or transportation of Hydrocarbons (together with
all accessions, additions and attachments to any thereof), including, but not by
way of limitation, all oil wells, gas wells, water wells, injection wells,
casing, tubing, tubular goods, rods, pumping units and engines, christmas trees,
platforms, derricks, separators, compressors, gun barrels, flow lines, tanks,
gas systems (for gathering, treating and compression), pipelines (including
gathering lines, laterals and trunklines), chemicals, solutions, water systems
(for treating, disposal and injection), power plants, poles, lines,
transformers, starters and controllers, machine shops, tools, storage yards and
equipment stored therein, buildings and camps, telegraph, telephone and other
communication systems, roads, loading docks, loading racks and shipping
facilities.

                  M. "Permitted Encumbrances" shall mean any or all of the
following:

                           (i) Lessors' royalties, overriding royalties,
         production payments, net profits interests and similar burdens on
         production from the Mortgaged Property;

                           (ii) Encumbrances that arise under operating
         agreements to secure payment of amounts which are not delinquent and
         are of a type and nature customary in the oil and gas industry;

                           (iii) Encumbrances that arise as a result of pooling
         and unitization agreements, declarations, orders or laws to secure
         payment of amounts which are not delinquent;

                           (iv) Encumbrances securing payments to mechanics and
         materialmen and Encumbrances securing payment of taxes, assessments or
         other governmental charges or levies that, in either case, are not
         delinquent or, if delinquent, are being contested in good faith in the
         normal course of business;

                           (v) consents to assignment by governmental
         authorities (a) that are obtained on or prior to the date hereof or (b)
         that are customarily obtained after the consummation of the
         transactions of the nature contemplated by this instrument;

                           (vi) farmouts, after payment interest and
         conventional rights of reassignment, of a type and nature customary in
         the oil and gas industry, obligating the Mortgagor to assign or
         reassign its interest in any portion of the Mortgaged Property to a
         third party, including





                               Exhibit Q - Page 4
   57

         in the event it intends to release or abandon such interest prior to
         the expiration of the primary term or other termination of such
         interest;

                           (vii) easements, rights-of-way, servitudes, permits,
         surface leases, surface use restrictions and other surface uses and
         impediments on, over or in respect of any of the Mortgaged Property
         that are not such as to interfere materially with the operation, value
         or use of any of the Mortgaged Property;

                           (viii) calls on or preferential rights to purchase
         production, of a type and nature and at a pricing structure customary
         in the oil and gas industry, held by parties other than the Mortgagor
         and its Subsidiaries;

                           (ix) covenants, conditions and other terms of the oil
         and gas leases and contracts, such covenants, conditions and terms of a
         type and nature customary in the oil and gas business, included in the
         Mortgaged Property;

                           (x) such Encumbrances as the Trustees have expressly
         waived in writing;

                           (xi) rights reserved to or vested in any municipality
         or governmental, tribal, statutory or public authority to control or
         regulate any of the Mortgaged Property in any manner, and all
         applicable laws, rules and orders of any municipality or governmental
         or tribal authority;

                           (xii) such Encumbrances which are validly existing
         and binding upon the Mortgagor's interest in the particular Mortgaged
         Properties as of the date of this Mortgage;

                           (xiii) Encumbrances permitted pursuant to Section
         5.2(b) of [either of] the Credit Agreement[s];

                           (xiv) judgment liens (A) in existence less than 15
         days after the entry thereof or (B) which execution has been stayed or
         the payment of which is covered in full (subject to a customary
         deductible) by insurance;

                           (xv) contractual obligations terminable upon no more
         than 90 days' prior notice to the counterparty thereunder providing for
         the sale of Hydrocarbons produced from the Mortgaged Properties;

                           (xvi) Encumbrances created under this instrument; and

                           (xvii) all other Encumbrances affecting any portion
         of the Mortgaged Property that individually or in the aggregate are not
         such as to interfere materially with the operation, value or use of any
         of the Mortgaged Property.

                  N. "Production Sale Contracts" shall mean contracts now in
effect, or hereafter entered into by the Mortgagor, or entered into by the
Mortgagor's predecessors in interest, for the sale,





                               Exhibit Q - Page 5
   58

purchase, exchange, gathering, transportation, treating or processing of
Hydrocarbons produced from the lands described in Exhibit A attached hereto and
made a part hereof.

                  O. "Secured Indebtedness" shall have the meaning set forth in
Section 1.2 hereof.

         NOW, THEREFORE, the Mortgagor, for and in consideration of the premises
and of the debts and trusts hereinafter mentioned, has granted, bargained, sold,
warranted, mortgaged, assigned, transferred and conveyed, and by these presents
does grant, bargain, sell, warrant, mortgage, assign, transfer and convey unto
the Trustees, in trust, with power of sale, for use and benefit of the
Collateral Agent for the equal and ratable benefit of the holders of the Secured
Indebtedness, all the Mortgagor's right, title and interest, whether now owned
or hereafter acquired, in and to all of the hereinafter described properties,
rights and interests; and, insofar as such properties, rights and interests
consist of equipment, general intangibles, accounts, contract rights, inventory,
fixtures, proceeds of collateral or any other personal property of a kind or
character defined in or subject to the applicable provisions of the Uniform
Commercial Code (as in effect in the appropriate jurisdiction with respect to
each of said properties, rights and interests), the Mortgagor hereby grants to
said Trustees, for the use and benefit of the Collateral Agent for the equal and
ratable benefit of the holders of the Secured Indebtedness, a security interest
therein; namely:

                  (a) the lands described in Exhibit A, and the oil and gas
         leases, the fee, mineral, overriding royalty, royalty and other
         interests which are specifically described in Exhibit A,

                  (b) the presently existing and (subject to the terms of
         Section 2.6 hereof) hereafter arising unitization, unit operating,
         communitization and pooling agreements and the properties covered and
         the units created thereby (including, without limitation, all units
         formed under orders, regulations, rules, approvals, decisions or other
         official acts of any federal, state or other governmental agency having
         jurisdiction) which are specifically described in Exhibit A or which
         relate to any of the properties and interests specifically described in
         Exhibit A,

                  (c) the Hydrocarbons which are in, under, upon, produced or to
         be produced from the lands described in Exhibit A,

                  (d) the Production Sale Contracts, and

                  (e) the Operating Equipment,

together with any and all corrections or amendments to, or renewals, extensions
or ratifications of, or replacements or substitutions for, any of the same, or
any instrument relating thereto, and all accounts, contracts, contract rights,
options, nominee agreements, operating agreements, processing agreements, farmin
agreements, farmout agreements, joint venture agreements, exploration
agreements, bottomhole agreements, dryhole agreements, support agreements,
acreage contribution agreements, insurance policies, title opinions, title
abstracts, title materials and information, files, records, writings, data
bases, information, systems, logs, well cores, fluid samples, production data
and reports, well testing data and reports, maps, seismic and geophysical,
geological and chemical data and information, interpretative and analytical
reports of any kind or nature, including, without limitation, reserve studies
and reserve evaluations, (to the extent




                               Exhibit Q - Page 6
   59

the assignment or release of such agreements, opinions, data, information
systems, logs, cores, samples, and reports is not restricted by any contract or
agreement which is of a type and nature customary in the oil and gas industry)
rights-of-way, franchises, easements, servitudes, surface leases, permits,
licenses, tenements, hereditaments, appurtenances, general intangibles, rents,
issues, profits, products and proceeds, whether now or hereafter existing or
arising, used or useful in connection with, covering, relating to, or arising
from or in connection with, any of the aforesaid in this granting clause
referenced, and all other things of value and incident thereto (including,
without limitation, any and all liens, lien rights, security interests and other
rights and interests) which the Mortgagor might at any time have or be entitled
to, all the aforesaid properties, rights and interests, together with any
additions thereto which may be subjected to the lien and security interest of
this instrument by means of supplements hereto, being hereinafter called the
"Mortgaged Property."

         Subject, however, to (i) the restrictions, exceptions, reservations,
conditions, limitations, interests and other matters, if any, set forth or
referred to in the specific descriptions of such properties and interests in
Exhibit A (including all presently existing royalties, overriding royalties,
payments out of production and other burdens which are referred to in Exhibit A
and which are taken into consideration in computing any percentage, decimal or
fractional interest as set forth in Exhibit A), any Permitted Encumbrances, (ii)
the assignment of production contained in Article III hereof, but only insofar
and so long as said assignment of production is not inoperative under the
provisions of Section 3.1 hereof, and (iii) the condition that none of the
Trustees, the Collateral Agent, the Agents, the Lenders, the Noteholders or any
part thereof shall be liable in any respect for the performance of any covenant
or obligation of the Mortgagor in respect of the Mortgaged Property.

         TO HAVE AND TO HOLD the Mortgaged Property unto the Trustees forever to
secure the payment of the Secured Indebtedness and to secure the performance of
the obligations of the Mortgagor herein contained.

         The Mortgagor, in consideration of the premises, hereby covenants and
agrees with the Trustees and the Collateral Agent as follows:

                                    ARTICLE I
                              Indebtedness Secured

         1.1 Items of Indebtedness Secured. The following items of indebtedness
are secured hereby:

                  (a) that certain Second Amended and Restated Credit Facility
         Agreement - [Primary Facility], dated as of March 19, 1999, by and
         among Pioneer Natural Resources Company (the "Borrower"), NationsBank,
         N.A., as Administrative Agent (the "Administrative Agent"), CIBC Inc.,
         as Documentation Agent, Morgan Guaranty Trust Company of New York, as
         Documentation Agent, Chase Bank of Texas, National Association, as
         successor-in-interest to The Chase Manhattan Bank, as Syndication
         Agent, the Co-Agents party thereto, and the Lenders from time to time
         parties thereto (herein, as the same may be amended, supplemented,
         restated or otherwise modified, the "Primary Credit Agreement"), which
         includes, without limitation, the Notes (as defined in the Primary
         Credit




                               Exhibit Q - Page 7
   60

         Agreement), Obligations (as defined in the Primary Credit Agreement)
         and liabilities of the Borrower under and in connection with the
         Primary Credit Agreement;

                  (b) [that certain Second Amended and Restated Credit Facility
         Agreement - [364-Day Facility], dated as of March 19, 1999, by and
         among Borrower, the Administrative Agent, CIBC Inc., as Documentation
         Agent, Morgan Guaranty Trust Company of New York, as Documentation
         Agent, Chase Bank of Texas, National Association, as
         successor-in-interest to The Chase Manhattan Bank, as Syndication
         Agent, the Co-Agents party thereto, and the Lenders from time to time
         parties thereto (herein, as the same may be amended, supplemented,
         restated or otherwise modified, the "364-Day Credit Agreement", and
         together with the Primary Credit Agreement, the "Credit Agreements"),
         which includes, without limitation, the Notes (as defined in the
         364-Day Credit Agreement), Obligations (as defined in the 364-Day
         Credit Agreement) and liabilities of the Borrower under and in
         connection with the 364-Day Credit Agreement;

                  (c)] The Indenture Notes;

                  (d) Any promissory note taken in extension or renewal of or in
         replacement or substitution for any of the Credit Agreement Notes or
         the Indenture Notes; and

                  (e) Any sums advanced or expenses or costs incurred by the
         Trustees or the Collateral Agent which are made or incurred pursuant
         to, or permitted by, the terms hereof, plus interest thereon at the
         rate herein specified or otherwise agreed upon, from the date of the
         advances or the incurring of such expenses or costs until reimbursed.

         1.2 Secured Indebtedness Defined. All the above items of indebtedness
are hereinafter collectively referred to as the "Secured Indebtedness."

                                   ARTICLE II
                       Particular Covenants and Warranties
                                of the Mortgagor

         2.1 Payment of the Secured Indebtedness. The Mortgagor will duly and
punctually pay the Secured Indebtedness, including each and every obligation
owing on account of the Credit Agreement Notes and the Indenture Notes.

         2.2 Warranties. The Mortgagor warrants and represents to the Trustees
and the Collateral Agent that (a) the oil and gas leases described in Exhibit A
hereto are valid, subsisting leases, superior and paramount to all other oil and
gas leases respecting the properties to which they pertain, (b) all producing
wells located on the lands described in Exhibit A have been drilled, operated
and produced in substantial compliance with all applicable laws, rules and
regulations of all authorities having jurisdiction and such wells are in fact
bottomed under and are producing from the lands described in Exhibit A or from
units in which such lands are unitized or pooled, (c) the Mortgagor has valid
and indefeasible title to each property right or interest constituting the
Mortgaged Property and has a good and legal right to grant and convey the same
to the Trustees, and (d) the Mortgaged Property is free from all encumbrances or
liens whatsoever, except for Permitted Encumbrances or as permitted by the
provisions of Section 2.5(f) hereof.




                               Exhibit Q - Page 8
   61

The Mortgagor will warrant and forever defend the Mortgaged Property unto the
Trustees against every person whomsoever lawfully claiming the same or any part
thereof, and the Mortgagor will maintain and preserve the lien and security
interest hereby created so long as any of the Secured Indebtedness remains
unpaid.

         2.3 Further Assurances. The Mortgagor will execute and deliver such
other and further instruments and will do such other and further acts as in the
opinion of the Trustees or the Collateral Agent may be necessary or desirable to
carry out more effectually the purposes of this instrument, including, without
limiting the generality of the foregoing, (a) proceeding with reasonable
diligence to promptly correct any Encumbrance which may hereafter be discovered
in the title to the Mortgaged Property other than Permitted Encumbrances, (b)
prompt correction of any defect in the execution and acknowledgment of this
instrument, and (c) prompt execution and delivery of all notices to parties
producing, purchasing or receiving proceeds of production from the Mortgaged
Property, and all division orders or transfer orders, any of which, in the
opinion of the Trustees or the Collateral Agent, is needed to transfer
effectually or to assist in transferring effectually to the Collateral Agent the
assigned proceeds of production from the Mortgaged Property.

         2.4 Taxes. Subject to the Mortgagor's right to contest the same, the
Mortgagor will promptly pay all taxes, assessments and governmental charges
legally imposed upon this instrument or upon the Mortgaged Property, or upon the
interest of the Trustees or the Collateral Agent, or upon the income and profits
thereof.

         2.5 Recording, etc. The Mortgagor will promptly, and at the Mortgagor's
expense, record, register, deposit and file this and every other instrument in
addition or supplemental hereto in such offices and places and at such times and
as often as may be necessary to preserve, protect and renew the lien and
security interest hereof as a first lien on and prior perfected security
interest in real or personal property, as the case may be, subject to the
Permitted Encumbrances, and the rights and remedies of the Trustees and of the
Collateral Agent, and otherwise will do and observe all things or matters
necessary or expedient to be done or observed by reason of any law or regulation
of any State or of the United States of America or of any other competent
authority, for the purpose of effectively creating, maintaining and preserving
the lien and security interest hereof on and in the Mortgaged Property, subject
to the Permitted Encumbrances.

         2.6 Pooling and Unitization of Mortgaged Property. Mortgagor shall have
the right, and is hereby authorized, without notice or consent to pool or
unitize all or any part of any tract of land described in Exhibit A, insofar as
related to the Mortgaged Property, with adjacent lands, leaseholds and other
interests, or enter into joint exploration or development agreements, when, in
the reasonable judgment of the Mortgagor, it is necessary or advisable to do so
in order to form a drilling unit to facilitate the orderly development of that
part of the Mortgaged Property affected thereby, or to comply with the
requirements of any law or governmental order or regulation relating to the
spacing of wells or proration of the production therefrom. Any unit so formed
may relate to one or more zones or horizons, and a unit formed for a particular
zone or horizon need not conform in area to any other unit relating to a
different zone or horizon, and a unit formed for the production of oil need not
conform in area with any unit formed for the production of gas. Upon written
request of the Trustees or the Collateral Agent, Mortgagor shall make available
to the Trustee and the Collateral Agent copies of all such existing pooling
agreements, declarations of pooling or other instruments creating such units.
The interest in any such unit attributable



                               Exhibit Q - Page 9
   62

to the Mortgaged Property (or any part thereof) included therein shall become a
part of the Mortgaged Property and shall be subject to the lien hereof in the
same manner and with the same effect as though such unit and the interest of the
Mortgagor therein were specifically described in Exhibit A.

         2.7 Right of Entry. The Mortgagor will permit the Trustees and the
Collateral Agent, or the agents of any of them, to enter upon the Mortgaged
Property, and all parts thereof, for the purpose of investigating and inspecting
the condition and operation thereof.

                                   ARTICLE III
                            Assignment of Production

         3.1 Assignment. As further security for the payment of the Secured
Indebtedness, the Mortgagor hereby transfers, assigns, warrants and conveys to
the Collateral Agent for the equal and ratable benefit of the holders of Secured
Indebtedness, effective as of the date hereof, at 7:00 A.M., local time, all
Hydrocarbons which are thereafter produced from and which accrue to the
Mortgaged Property, and all proceeds therefrom. All parties producing,
purchasing or receiving any such Hydrocarbons, or having such, or proceeds
therefrom, in their possession for which they or others are accountable to the
Collateral Agent by virtue of the provisions of this Article, are authorized and
directed to treat and regard the Collateral Agent as the assignee and transferee
of the Mortgagor and entitled in the Mortgagor's place and stead to receive such
Hydrocarbons and all proceeds therefrom; and said parties and each of them shall
be fully protected in so treating and regarding the Collateral Agent and shall
be under no obligation to see to the application by the Collateral Agent of any
such proceeds or payments received by it. Notwithstanding the other provisions
of this Article including the foregoing provisions of this Section 3.1, the
Collateral Agent or any receiver appointed in judicial proceedings for the
enforcement of this instrument shall have the right to receive all of the
Hydrocarbons herein assigned and the proceeds therefrom only after any event of
default as described in the provisions of Section 4.1 hereof shall have occurred
and be continuing. Upon any sale of the Mortgaged Property or any part thereof
pursuant to Article V, the Hydrocarbons thereafter produced from the property so
sold, and the proceeds therefrom, shall be included in such sale and shall pass
to the purchaser free and clear of the assignment contained in this Article.

         3.2 Application of Proceeds. All payments received by the Collateral
Agent pursuant to Section 3.1 hereof shall be placed in a cash collateral
account at the principal office of the Collateral Agent and on the first
Business Day (as defined in the Credit Agreements) of each calendar month
applied as follows:

                  First: To the payment and satisfaction of all costs and
         expenses incurred in connection with the collection of such proceeds,
         and to the payment of all items of the Secured Indebtedness not
         evidenced by any Credit Agreement Note or any Indenture Note.

                  Second: To the payment of those items of the Secured
         Indebtedness then due and owing, pro rata according to each Secured
         Indebtedness holder's percentage of such items outstanding at the time
         of such payment.

                  Third:  The balance, if any, shall be released to the
         Mortgagor.


                              Exhibit Q - Page 10
   63


         3.3 No Liability of the Collateral Agent in Collecting. The Collateral
Agent is hereby absolved from all liability for failure to enforce collection of
any proceeds so assigned (and no such failure shall be deemed to be a waiver of
any right of the Collateral Agent or the Trustees) and from all other
responsibility in connection therewith, except the responsibility to account to
the Mortgagor for funds actually received.

         3.4 Assignment Not a Restriction on the Collateral Agent's Rights.
Nothing herein contained shall detract from or limit the absolute obligation of
the Mortgagor to make payment of the Secured Indebtedness regardless of whether
the proceeds assigned by this Article are sufficient to pay the same, and the
rights under this Article shall be in addition to all other security now or
hereafter existing to secure the payment of the Secured Indebtedness.

         3.5 Indemnity. The Mortgagor agrees to indemnify the Trustees and the
Collateral Agent against all claims, actions, liabilities, judgments, costs,
attorneys' fees or other charges of whatsoever kind or nature (all hereinafter
in this Section 3.6 called "claims") made against or incurred by them or any of
them as a consequence of the assertion, either before or after the payment in
full of the Secured Indebtedness, that they or any of them received Hydrocarbons
herein assigned or the proceeds thereof claimed by third persons, and the
Trustees and the Collateral Agent shall have the right to defend against any
such claims, employing attorneys therefor, and unless furnished with reasonable
indemnity, they or any of them shall have the right to pay or compromise and
adjust all such claims. The Mortgagor will indemnify and pay to the Trustees or
the Collateral Agent, as the case may be, any and all such amounts as may be
paid in respect thereof or as may be successfully adjudged against the Trustees
or the Collateral Agent or any of them. The obligations of the Mortgagor as
hereinabove set forth in this Section 3.5 shall survive the release,
termination, foreclosure or assignment of this instrument or any sale hereunder.

                                   ARTICLE IV
                                Events of Default

         4.1 Events of Default Hereunder. Default in the payment of principal of
any Secured Indebtedness when due or default (and such default shall continue
unremedied for five (5) days or such longer period during which the holders
thereof, or any Indenture Trustee for the holders thereof, do not have the power
to cause such Secured Indebtedness to become immediately payable in full) in the
payment of interest on any Secured Indebtedness when due, so long as such
default shall not have been remedied shall be an "event of default" hereunder.

                                    ARTICLE V
                           Enforcement of the Security

         5.1 Power of Sale of Real Property Constituting a Part of the Mortgaged
Property. Upon the occurrence of an event of default and if such event shall be
continuing, the Trustees shall have the right and power to sell, to the extent
permitted by law, at one or more sales, as an entirety or in parcels, as they
may elect, the real property constituting a part of the Mortgaged Property, at
such place or places and otherwise in such manner and upon such notice as may be
required by law, or, in the absence of any such requirement, as the Trustees may
deem appropriate, and to make conveyance to the purchaser or purchasers; and the
Mortgagor shall warrant title to such real property, subject to Permitted
Encumbrances, to such purchaser or purchasers. Any public sale may be adjourned
without the necessity of announcement




                              Exhibit Q - Page 11
   64

at the time and place of such sale and without public notice except as may be
required by law. The Trustee may sell, transfer and convey any part of the
Mortgaged Property on such terms of credit or part cash and part credit, secured
by contract or agreement for sale or mortgage, or otherwise as shall appear to
the Trustee to be most advantageous and for such price or prices as can
reasonably be obtained therefor, and in the event of a sale on credit or for
part cash or part credit, whether by way of contract for sale or by conveyance
or transfer and mortgage, neither the Trustee, nor Collateral Agent or holders
of Secured Indebtedness are to be accountable for or charged with any monies
until the same shall actually be received in cash. The right of sale hereunder
shall not be exhausted by one or any sale, and the Trustees may make other and
successive sales until all of the trust estate be legally sold. If the proceeds
of such sale or sales of less than the whole of the Mortgaged Property shall be
less than the aggregate of the indebtedness secured hereby and the expense of
executing this trust as provided herein, this Mortgage and the lien and charge
hereof shall remain in full force and effect as to the unsold portion of the
Mortgaged Property just as though no sale had been made; provided, however, that
the Mortgagor shall never have any right to require the sale of less than the
whole of the Mortgaged Property but the Collateral Agent shall have the right,
at its election, to request the Trustee to sell less than the whole of the
Mortgaged Property. With respect to that portion, if any, of the Mortgaged
Property situated in the State of Wyoming, this instrument may be foreclosed by
advertisement and sale as provided by applicable Wyoming statutes. With respect
to that portion, if any, of the Mortgaged Property situated in the State of
Oklahoma, the Collateral Agent shall have the right and power at its option to
declare the Secured Indebtedness hereby secured due and payable and to sell, or
direct the Trustees to sell, the "real estate," as such term is defined under
the provisions of 46 O.S. Supp. 1986, ss.42, constituting a part of the
Mortgaged Property, all under the terms of 46 O.S. Supp. 1986, ss.40 et seq.,
and shall, to the extent permitted by law, have the other rights conferred on
the Trustees under the provisions of this instrument.

         5.2 Rights of the Trustees with Respect to Personal Property
Constituting a Part of the Mortgaged Property. Upon the occurrence of an event
of default and if such event shall be continuing, the Trustees will have all
rights and remedies granted by law, and particularly by the Uniform Commercial
Code, including, but not limited to, the right to take possession of all
personal property constituting a part of the Mortgaged Property, and for this
purpose the Trustees may enter upon any premises on which any or all of such
personal property is situated and take possession of and operate such personal
property (or any portion thereof) or remove it therefrom. The Trustees may
require the Mortgagor to assemble such personal property and make it available
to the Trustees at a place to be designated by the Trustees which is reasonably
convenient to all parties. Unless such personal property is perishable or
threatens to decline speedily in value or is of a type customarily sold on a
recognized market, the Trustees will give the Mortgagor reasonable notice of the
time and place of any public sale or of the time after which any private sale or
other disposition of such personal property is to be made. This requirement of
sending reasonable notice will be met if the notice is mailed by first-class
mail, postage prepaid, to the Mortgagor at the address shown below the
signatures at the end of this instrument at least five (5) days before the time
of the sale or disposition.

         5.3 Rights of the Trustees with Respect to Fixtures Constituting a Part
of the Mortgaged Property. Upon the occurrence of an event of default and if
such event shall be continuing, the Trustees may elect to treat the fixtures
constituting a part of the Mortgaged Property as either real property collateral
or personal property collateral and then proceed to exercise such rights as
apply to such type of collateral.



                              Exhibit Q - Page 12
   65

         5.4 Judicial Proceedings. Upon occurrence of an event of default and if
such event shall be continuing, the Trustees, in lieu of or in addition to
exercising any power of sale hereinabove given, may proceed by a suit or suits
in equity or at law, whether for a foreclosure hereunder, or for the sale of the
Mortgaged Property, or for the specific performance of any covenant or agreement
herein contained or in aid of the execution of any power herein granted, or for
the appointment of a receiver pending any foreclosure hereunder or the sale of
the Mortgaged Property, or for the enforcement of any other appropriate legal or
equitable remedy.

         5.5 Possession of the Mortgaged Property. It shall not be necessary for
the Trustees to have physically present or constructively in their possession at
any sale held by the Trustees or by any court, receiver or public officer any or
all of the Mortgaged Property; and the Mortgagor shall deliver to the purchasers
at such sale on the date of sale the Mortgaged Property purchased by such
purchasers at such sale, and if it should be impossible or impracticable for any
of such purchasers to take actual delivery of the Mortgaged Property, then the
title and right of possession to the Mortgaged Property shall pass to such
purchaser at such sale as completely as if the same had been actually present
and delivered.

         5.6 Certain Aspects of a Sale. Each Lender or Noteholder shall have the
right to become the purchaser at any sale held by the Trustees or by any court,
receiver or public officer, and such Lender shall have the right to credit upon
the amount of the bid made therefor the amount payable out of the net proceeds
of such sale to it. Recitals contained in any conveyance made to any purchaser
at any sale made hereunder shall conclusively establish the truth and accuracy
of the matters therein stated, including, without limiting the generality of the
foregoing, nonpayment of the unpaid principal sum of, and the interest accrued
on, the Secured Indebtedness after the same have become due and payable,
advertisement and conduct of such sale in the manner provided herein or
appointment of any successor Trustee hereunder.

         5.7 Receipt to Purchaser. Upon any sale, whether made under the power
of sale herein granted and conferred or by virtue of judicial proceedings, the
receipt of the Trustees, or of the officer making sale under judicial
proceedings, shall be sufficient discharge to the purchaser or purchasers at any
sale for his or their purchase money, and such purchaser or purchasers, or his
or their assigns or personal representatives, shall not, after paying such
purchase money and receiving such receipt of the Trustees or of such officer
therefor, be obliged to see to the application of such purchase money, or be in
anywise answerable for any loss, misapplication or nonapplication thereof.

         5.8 Effect of Sale. Any sale or sales of the Mortgaged Property,
whether under the power of sale herein granted and conferred or by virtue of
judicial proceedings, shall operate to divest all right, title, interest, claim
and demand whatsoever either at law or in equity, of the Mortgagor of, in and to
the premises and the property sold, and shall be a perpetual bar, both at law
and in equity, against the Mortgagor, and the Mortgagor's successors or assigns,
and against any and all persons claiming or who shall thereafter claim all or
any of the property sold from, through or under the Mortgagor or the Mortgagor's
successors or assigns. Nevertheless, the Mortgagor, if requested by the Trustees
so to do, shall join in the execution and delivery of all proper conveyances,
assignments and transfers of the properties so sold.





                              Exhibit Q - Page 13
   66

         5.9 Application of Proceeds. The proceeds of any sale of the Mortgaged
Property, or any part thereof, whether under the power of sale herein granted
and conferred or by virtue of judicial proceedings, shall be applied as follows:

                  First: To the payment and satisfaction of all reasonable costs
         and expenses incurred by the Trustees in the performance of their
         duties including, without limiting the generality of the foregoing,
         costs and expenses of any entry, or taking of possession, of any sale,
         or advertisement thereof, and of conveyances, and as well, court costs,
         compensation of agents and employees and reasonable legal fees.

                  Second: To a payment to the Collateral Agent, equal in amount
         to the Secured Indebtedness outstanding at the time of the payment.

                  Third: Any surplus thereafter remaining shall be paid to the
         Mortgagor or the Mortgagor's successors or assigns, as their interests
         shall appear.

         All payments to the Collateral Agent shall be paid into such account as
the Collateral Agent shall specify from time to time by notice to the Trustees,
in same day or immediately available funds. The Collateral Agent shall promptly
remit in same day funds to each holder of Secured Indebtedness its pro rata
share, based on the amount of outstanding Secured Indebtedness owed to it, of
such payments received by the Collateral Agent.

         5.10 The Mortgagor's Waiver of Appraisement, Marshalling and Other
Rights. The Mortgagor agrees, to the full extent that the Mortgagor may lawfully
so agree, that the Mortgagor will not at any time insist upon or plead or in any
manner whatever claim the benefit of any appraisement, valuation, stay,
extension or redemption law now or hereafter in force, in order to prevent or
hinder the enforcement or foreclosure of this instrument or the absolute sale of
the Mortgaged Property or the possession thereof by any purchaser at any sale
made pursuant to any provision hereof, or pursuant to the decree of any court of
competent jurisdiction; but the Mortgagor, for the Mortgagor and all who may
claim through or under the Mortgagor, so far as the Mortgagor or those claiming
through or under the Mortgagor now or hereafter lawfully may, hereby waives the
benefit of all such laws; provided, however, that appraisement of any of the
Mortgaged Property located in the State of Oklahoma is hereby expressly waived
or not, at the option of the Trustees, such option to be exercised prior to or
at the time the judgment is rendered in any foreclosure hereof. The Mortgagor,
for the Mortgagor and all who may claim through or under the Mortgagor, waives,
to the extent that the Mortgagor may lawfully do so, any and all right to have
the Mortgaged Property marshalled upon any foreclosure of the lien hereof, or
sold in inverse order of alienation, and agrees that the Trustees or any court
having jurisdiction to foreclose such lien may sell the Mortgaged Property as an
entirety. The Mortgagor, for the Mortgagor and all who may claim through or
under the Mortgagor, further waives, to the full extent that the Mortgagor may
lawfully do so, any requirement for posting a receiver's bond or replevin bond
or other similar type of bond if the Trustees commence an action for appointment
of a receiver or an action for replevin to recover possession of any of the
Mortgaged Property. If any law in this paragraph referred to and now in force,
of which the Mortgagor or the Mortgagor's successor or successors might take
advantage despite the provisions hereof, shall hereafter be repealed or cease to
be in force, such law shall not thereafter be deemed to constitute any part of
the contract herein contained or to preclude the operation or application of the
provisions of this




                              Exhibit Q - Page 14
   67

paragraph. Pursuant to Section 39-5-19, New Mexico Statutes, Annotated, 1978
Comp., as amended, the Mortgagor agrees that as to the Mortgaged Property
situated in the State of New Mexico, the redemption period shall be shortened to
one (1) month. The Mortgagor hereby waives all rights of appraisement, sale,
homestead or redemption allowed under any law or laws of the State of Arkansas,
and especially redemption under the Act of the General Assembly of the State of
Arkansas approved May 8, 1899, and acts amendatory thereto.

         5.11 Costs and Expenses. All reasonable costs and expenses (including
reasonable attorneys' fees) incurred by the Trustees and the Collateral Agent in
protecting and enforcing their rights hereunder, shall constitute a demand
obligation owing by the Mortgagor to the party incurring such costs and expenses
and shall draw interest at an annual rate equal to the "Prime Rate" (the "Prime
Rate") as published in the Wall Street Journal from time to time (or if for a
day when such rate is note so published, at the rate for the next preceding day
when so published) from time to time plus two percent (2%) until paid, all of
which shall constitute a portion of the Secured Indebtedness.

         5.12 Sale of the Mortgaged Property in Mississippi. After the
occurrence of an event of default, the Trustees, their successors or
substitutes, are authorized and empowered, and it shall be their special duty at
the request of the Collateral Agent (which request is hereby presumed), to
enforce this trust and to sell the Mortgaged Property located in the State of
Mississippi, as an entirety or in parcels, as the Trustees acting may designate,
to satisfy the Secured Indebtedness then unpaid, after having published notice
of the day, time, place and terms of sale in some newspaper published in the
county or counties, as the case may be, in which the Mortgaged Property in the
State of Mississippi is situated for three (3) consecutive weeks preceding date
of sale, and by posting one notice of such sale at the Court House of each
county in which the Mortgaged Property is situated for said period of time. In
the event the Mortgaged Property is located in more than one county or in two
judicial districts of the same county in the State of Mississippi, the Trustees
or their substitutes or successors in trust shall have the power, in case they
are directed to foreclose under this instrument, to select the county or
judicial district in which the sale shall be made and their selection shall be
binding on the Mortgagor and the holders of Secured Indebtedness and all persons
claiming through or under them, whether by contract or law. The Trustees or
their substitutes or any successors in said Trust shall have full power to fix
the day, time, place and terms of sale and may appoint or delegate any one or
more persons as agent to perform any act or acts necessary or incident to any
sale held by the Trustees, including the posting of notices and the conduct of
sale, but in the name and on behalf of the Trustees, their substitutes or
successors. The Mortgagor waives the provisions of Section 89-1-55 of the
Mississippi Code of 1972, Recompiled, and Laws amendatory thereto, if any, as
far as said section restricts the right of the Trustees to offer at sale more
than 160 acres at one time, and the Trustees, their substitutes or successors
may, in their discretion, offer the Mortgaged Property as a whole or in such
part or parts as they may deem desirable, regardless of the manner in which it
may be described. Any sale made by the Trustees hereunder may be adjourned by
announcement at the time and place appointed for such sale without further
notice except as may be required by law.

         5.13 Sale of the Mortgaged Property in Texas. If any Credit Agreement
Note or any Indenture Note is not paid when due, whether by acceleration or
otherwise, the Trustees are hereby authorized and empowered to sell any part of
the Mortgaged Property located in the State of Texas at public sale to the
highest bidder for cash in the area at the county courthouse of the county in
Texas in which the Texas portion of the Mortgaged Property or any part thereof
is situated, as herein described, designated by such




                              Exhibit Q - Page 15
   68

county's commissioner's court for such proceedings, or if no area is so
designated, at the door of the county courthouse of said county, at a time
between the hours of 10:00 A.M. and 4:00 P.M. which is no later than three (3)
hours after the time stated in the notice described immediately below as the
earliest time at which such sale would occur on the first Tuesday of any month,
after advertising the earliest time at which said sale would occur, the place,
and terms of said sale, and the portion of the Mortgaged Property to be sold, by
(a) posting (or by having some person or persons acting for the Trustees post)
for at least twenty-one (21) days preceding the date of the sale, written or
printed notice of the proposed sale at the courthouse door of said county in
which the sale is to be made; and if such portion of the Mortgaged Property lies
in more than one county, one such notice of sale shall be posted at the
courthouse door of each county in which such part of the Mortgaged Property is
situated and such part of the Mortgaged Property may be sold in the area at the
county courthouse of any one of such counties designated by such county's
commissioner's court for such proceedings, or if no area is designated, at the
courthouse door of such county, and the notice so posted shall designate in
which county such property shall be sold, and (b) filing in the office of the
county clerk of each county in which any part of the Texas portion of the
Mortgaged Property which is to be sold at such sale is situated a copy of the
notice posted in accordance with the preceding clause (a). In addition to such
posting and filing of notice, the Collateral Agent, acting on behalf of the
holders of the Secured Indebtedness shall, at least twenty-one (21) days
preceding the date of sale, serve or cause to be served written notice of the
proposed sale by certified mail on the Mortgagor and on each other debtor, if
any, obligated to pay the Secured Indebtedness according to the records of the
Collateral Agent, the Lenders, the Noteholders or other holders of the Secured
Indebtedness. Service of such notice shall be completed upon deposit of the
notice, enclosed in a postpaid wrapper properly addressed to the Mortgagor and
such other debtors at their most recent address or addresses as shown by the
records of the Collateral Agent in a post office or official depository under
the care and custody of the United States Postal Service. The affidavit of any
person having knowledge of the facts to the effect that such a service was
completed shall be prima facie evidence of the fact of service. The Mortgagor
agrees that no notice of any sale, other than as set out in this paragraph, need
be given by the Trustees, the Collateral Agent or any other person. The
Mortgagor hereby designates as its address for the purpose of such notice the
address set out on the signature page hereof; and agrees that such address shall
be changed only by depositing notice of such change enclosed in a postpaid
wrapper in a post office or official depository under the care and custody of
the United States Postal Service, certified mail, postage prepaid, return
receipt requested, addressed to the Collateral Agent at the address for the
Collateral Agent set out herein (or to such other address as the Collateral
Agent may have designated by notice given as above provided to the Mortgagor and
such other debtors). Any such notice of change of address of the Mortgagor or
other debtors or of the Collateral Agent shall be effective three (3) Business
Days after such deposit if such post office or official depository is located in
the State of Texas, otherwise to be effective upon receipt. The Mortgagor
authorizes and empowers the Trustees to sell the Texas portion of the Mortgaged
Property in lots or parcels or in its entirety as the Trustees shall deem
expedient; and to execute and deliver to the purchaser or purchasers thereof
good and sufficient deeds of conveyance thereto by fee simple title, with
evidence of general warranty by the Mortgagor, and the title of such purchaser
or purchasers when so made by the Trustees, the Mortgagor binds itself to
warrant and forever defend. Where portions of the Mortgaged Property lie in
different counties, sales in such counties may be conducted in any order that
the Trustees may deem expedient; and one or more such sales may be conducted in
the same month, or in successive or different months as the Trustees may deem
expedient. Notwithstanding anything to the contrary contained herein, the
Trustees may postpone the sale provided for in this Section 5.13 at any time
without the necessity of a public announcement. The provisions hereof



                              Exhibit Q - Page 16
   69

with respect to the posting and giving of notices of sale are intended to comply
with the provisions of Section 51.002 of the Property Code of the State of
Texas, as in force and effect on January 1, 1992, and in the event the
requirements, or any notice, under such Section 51.002 of the Property Code of
the State of Texas shall be eliminated or the prescribed manner of giving such
notices modified by future amendment to, or adoption of any statute superseding,
Section 51.002 of the Property Code of the State of Texas, the requirement for
such particular notices shall be deemed stricken from or modified in this
instrument in conformity with such amendment or superseding statute, effective
as of the effective date thereof.

         5.14 Operation of the Mortgaged Property by the Trustees. Upon the
occurrence of an event of default and so long as such event of default is
continuing and in addition to all other rights herein conferred on the Trustees,
the Trustees (or any person, firm or corporation designated by the Trustees)
shall have the right and power, but shall not be obligated, to enter upon and
take possession of any of the Mortgaged Property, and to exclude the Mortgagor,
and the Mortgagor's agents or servants, wholly therefrom, and to hold, use,
administer, manage and operate the same to the extent that the Mortgagor shall
be at the time entitled and in its place and stead. The Trustees, or any person,
firm or corporation designated by the Trustees, may operate the same without any
liability to the Mortgagor in connection with such operations, except to use
ordinary care in the operation of such properties, and the Trustees or any
person, firm or corporation designated by the Trustees, shall have the right to
collect, receive and receipt for all Hydrocarbons produced and sold from said
properties, to make repairs, purchase machinery and equipment, conduct work-over
operations, drill additional wells and to exercise every power, right and
privilege of the Mortgagor with respect to the Mortgaged Property. When and if
the expenses of such operation and development (including costs of unsuccessful
work-over operations or additional wells) have been paid and the Secured
Indebtedness paid, said properties shall, if there has been no sale or
foreclosure, be returned to the Mortgagor.

                                   ARTICLE VI
                            Miscellaneous Provisions

         6.1 Successor Trustees. Any Trustee may resign in writing addressed to
the Collateral Agent or may be removed at any time with or without cause by an
instrument in writing duly executed by the Collateral Agent. In case of the
death, resignation or removal of a Trustee, one or more successor Trustees may
be appointed by the Collateral Agent by instrument of substitution complying
with any applicable requirements of law, and in the absence of any such
requirement without formality other than appointment and designation in writing.
Such appointment and designation shall be full evidence of the right and
authority to make the same and of all facts therein recited, and upon the making
of any such appointment and designation this conveyance shall vest in the named
successor Trustee or Trustees all the estate and title of the prior Trustee in
all of the Mortgaged Property, and he or they shall thereupon succeed to all the
rights, powers, privileges, immunities and duties hereby conferred upon the
prior Trustee. All references herein to the Trustees shall be deemed to refer to
the Trustees from time to time acting hereunder.

         6.2 Actions or Advances by the Collateral Agent or the Trustees. Each
and every covenant herein contained shall be performed and kept by the Mortgagor
solely at the Mortgagor's expense. If the Mortgagor shall fail to perform or
keep any of the covenants of whatsoever kind or nature contained in this
instrument, the Collateral Agent, the Trustees or any receiver appointed
hereunder, may, but shall not be




                              Exhibit Q - Page 17
   70

obligated to, take action and/or make advances to perform the same in the
Mortgagor's behalf, and the Mortgagor hereby agrees to repay the expense of such
action and such advances upon demand plus interest at an annual rate equal to
the Prime Rate plus two percent (2%) until paid or, in the event any promissory
note evidences such indebtedness, upon the terms and conditions thereof. No such
advance or action by the Collateral Agent, the Trustees or any receiver
appointed hereunder shall be deemed to relieve the Mortgagor from any default
hereunder.

         6.2 Defense of Claims. The Mortgagor will notify the Trustees, in
writing, promptly of the commencement of any legal proceedings affecting the
lien or security interest hereof or the Mortgaged Property, or any part thereof,
and will take such action, employing attorneys agreeable to the Trustees and the
Collateral Agent, as may be necessary or appropriate to preserve the
Mortgagor's, the Trustees' and the Collateral Agent's rights affected thereby
and/or to hold harmless the Trustees or the Collateral Agent in respect of such
proceedings; and should the Mortgagor fail or refuse to take any such action,
the Trustees or the Collateral Agent may, upon giving prior written notice
thereof to the Mortgagor, take such action in behalf and in the name of the
Mortgagor and at the Mortgagor's expense. The obligations of the Mortgagor as
hereinabove set forth in this Section 6.3 shall survive the release,
termination, foreclosure or assignment of this instrument or any sale hereunder.

         6.3 The Mortgaged Property to Revert. If the Secured Indebtedness shall
be fully paid and all the commitments and obligations of the Lenders under the
Credit Agreements shall have been terminated in writing and the covenants herein
contained and contained in the Credit Agreements shall be well and truly
performed, then all of the Mortgaged Property shall revert to the Mortgagor and
the entire estate, right, title and interest of the Trustees and the holders of
Secured Indebtedness shall thereupon cease; and the Trustees and the Collateral
Agent in such case shall, upon the request of the Mortgagor and at the
Mortgagor's cost and expense, deliver to the Mortgagor proper instruments
acknowledging satisfaction of this instrument. The foregoing notwithstanding,
this instrument is a Line of Credit Mortgage and until the termination in
writing of the Credit Agreements and the occurrence of the other events
described in the past sentence of this Section, this Mortgage, and the priority
and perfection of the liens created hereunder should continue in full force and
effect even if at any time or from time to time there are no moneys outstanding
under the Credit Agreements.

         6.4 Renewals, Amendments and Other Security. Renewals and extensions of
the Secured Indebtedness may be given at any time and amendments may be made to
agreements relating to any part of such Secured Indebtedness or the Mortgaged
Property and the Trustees and the holders of Secured Indebtedness may take or
may now hold other security for the Secured Indebtedness, all without notice to
or consent of the Mortgagor. The Trustees or the holders of Secured Indebtedness
may resort first to such other security or any part thereof or first to the
security herein given or any part thereof, or from time to time to either or
both, even to the partial or complete abandonment of either security, and such
action shall not be a waiver of any rights conferred by this instrument, which
shall continue as a first lien upon and prior perfected security interest in the
Mortgaged Property not expressly released until the Secured Indebtedness is
fully paid.

         6.5 Instrument an Assignment, etc. This instrument shall be deemed to
be and may be enforced from time to time as an assignment, chattel mortgage,
contract, deed of trust, financing statement, real estate mortgage, or security
agreement, and from time to time as any one or more thereof.





                              Exhibit Q - Page 18
   71

         6.6 Limitation on Interest. No provision of this instrument shall
require the payment or permit the collection of interest in excess of the
maximum permitted by applicable law or which is otherwise contrary to law. If
any excess of interest in such respect is herein provided for, or shall be
adjudicated to be so provided for herein, the Mortgagor shall not be obligated
to pay such excess.

         6.7 Unenforceable or Inapplicable Provisions. If any provision hereof
is invalid or un enforceable in any jurisdiction, the other provisions hereof
shall remain in full force and effect in such jurisdiction, and the remaining
provisions hereof shall be liberally construed in favor of the Trustees and the
Collateral Agent in order to effectuate the provisions hereof, and the
invalidity of any provision hereof in any jurisdiction shall not affect the
validity or enforceability of any such provision in any other jurisdiction. Any
reference herein contained to a statute or law of a state in which no part of
the Mortgaged Property is situated shall be deemed inapplicable to, and not used
in, the interpretation hereof.

         6.8 Rights Cumulative. Each and every right, power and remedy herein
given to the Trustees or the Collateral Agent shall be cumulative and not
exclusive; and each and every right, power and remedy whether specifically
herein given or otherwise existing may be exercised from time to time and so
often and in such order as may be deemed expedient by the Trustees and the
Collateral Agent, as the case may be, and the exercise, or the beginning of the
exercise, of any such right, power or remedy shall not be deemed a waiver of the
right to exercise, at the same time or thereafter, any other right, power or
remedy. No delay or omission by the Trustees or the Collateral Agent or any of
them in the exercise of any right, power or remedy shall impair any such right,
power or remedy or operate as a waiver thereof or of any other right, power or
remedy then or thereafter existing. [In addition to all the rights and remedies
granted hereunder, the Mortgagor agrees to comply with all statutory mortgage
covenants and agree that this Mortgage shall be subject to the statutory
mortgage condition.](1)

         6.9 Waiver by the Trustees. Any and all covenants in this instrument
may from time to time by instrument in writing signed by the Trustees be waived
to such extent and in such manner as the Trustees may desire, but no such waiver
shall ever affect or impair either the Trustees' or the Collateral Agent's
rights or liens or security interests hereunder, except to the extent
specifically stated in such written instrument.

         6.10 Action by Individual Trustee. Any Trustee from time to time
serving hereunder shall have the absolute right, acting individually, to take
any action and to give any consent and to exercise any right, remedy, power,
privilege or authority conferred upon the Trustees, and any action taken by
either Trustee from time to time serving hereunder shall be binding upon the
other Trustee and no person dealing with either Trustee from time to time
serving hereunder shall be obligated to confirm the power and authority of such
Trustee to act without the concurrence of the other Trustee. In this instrument,
the term "Trustee" shall mean the Trustees hereinabove named, or either of them,
as the context requires, and any successor Trustee.

         6.11 Miscellaneous Warranties. The Mortgagor additionally warrants and
represents to the Trustees and the Collateral Agent that (a) the execution and
delivery of this instrument, and the


- ---------------------
         (1)       To be used in Mortgages to be filed in New Mexico.


                              Exhibit Q - Page 19
   72

performance by the Mortgagor of its obligations hereunder, are within the
corporate, partnership or other powers of the Mortgagor and have been duly
authorized by all necessary corporate, partnership or other action on the part
of the Mortgagor, and (b) this instrument has been duly executed and delivered
on behalf of the Mortgagor and is the legal, valid and binding obligation of the
Mortgagor, enforceable in accordance with its terms except as such
enforceability is subject to the effect of (i) any applicable bankruptcy,
insolvency, reorganization or similar laws relating to or affecting creditors'
rights generally and (ii) general principles of equity (regardless of whether
such enforceability is considered in a proceeding in equity or at law, including
without limitation, concepts of materiality, reasonableness, good faith and fair
dealing, and (c) the execution, delivery and performance of this instrument do
not and will not contravene or conflict with the organizational documents of the
Mortgagor or, to the best knowledge of the Mortgagor, violate or constitute a
default under any law, any presently existing requirement or restriction imposed
by judicial, arbitral or any governmental instrumentality.

         6.12 Successors and Assigns. This instrument is binding upon the
Mortgagor, the Mortgagor's successors and assigns, and shall inure to the
benefit of the Trustees, their successors, and the Collateral Agent, its
successors and assigns, and the provisions hereof shall likewise be covenants
running with the land.

         6.13 Article and Section Headings. The article and section headings in
this instrument are inserted for convenience of reference and shall not be
considered a part of this instrument or used in its interpretation.

         6.14 Execution in Counterparts. This instrument may be executed in any
number of counterparts, each of which shall for all purposes be deemed to be an
original and all of which are identical, except that, to facilitate recordation
or filing, in any particular counterpart portions of Exhibit A hereto which
describe properties situated in counties other than the county in which such
counterpart is to be recorded or filed may have been omitted.

         6.15 Special Filing as Financing Statement. This Mortgage and Deed of
Trust shall likewise be a Security Agreement and a Financing Statement. This
Mortgage and Deed of Trust shall be filed for record, among other places, in the
real estate records of each county in which any portion of the real property
covered by the oil and gas leases described in Exhibit A hereto is situated,
and, when filed in such counties shall be effective as a financing statement
covering fixtures located on oil and gas properties, which oil and gas
properties (and accounts arising therefrom) are to be financed at the wellheads
of the wells located on the real property described in Exhibit A hereto. At the
option of the Collateral Agent, a carbon, photographic or other reproduction of
this instrument or of any financing statement covering the Mortgaged Property or
any portion thereof shall be sufficient as a financing statement and may be
filed as such.

         6.16 Notices. Except as otherwise specifically provided for herein, all
notices, demands, instructions and other communications required or permitted to
be given to or made upon any party hereto shall be in writing and shall be
personally delivered or sent by certified mail, postage prepaid, return receipt
requested, or by telecopier, and shall be deemed to be given for purposes of
this instrument on the day that such writing is delivered or sent to the
intended recipient thereof in accordance with the provisions of this Section
6.16. Unless otherwise specified in a notice sent or delivered in accordance
with the foregoing




                              Exhibit Q - Page 20
   73

provisions of this Section 6.16, notices, demands, instructions and other
communications in writing shall be given to or made upon the respective parties
hereto at their respective addresses (or to their respective telecopier numbers)
indicated on the signature page(s) hereof.

         6.17 Release Upon Disposition; Termination.

         (a) From time to time during the term of this Agreement, unless an
event of default shall have occurred and be continuing, the Trustees and the
Collateral Agent shall execute, acknowledge and deliver to the Mortgagor a
release from this instrument of Mortgaged Properties in connection with the
sale, transfer or other disposition of such Mortgaged Properties by the
Mortgagor, other than a sale, transfer or disposition to Borrower or any
Subsidiary of Borrower and other than the mortgaging, pledging, securing or
granting of a lien, mortgage or security interest in the Mortgaged Properties to
any of them. Upon the receipt by the Collateral Agent of an Officer's
Certificate certifying that no event of default has occurred and is continuing
and that certain Mortgaged Properties described in such Officer's Certificate,
or an attachment thereto, are to be sold, transferred or disposed of by the
Mortgagor pursuant to a bona fide agreement, other than a sale, transfer or
disposition to Borrower or any Subsidiary of Borrower and other than the
mortgaging, pledging, securing or granting of a lien, mortgage or security
interest in the Mortgaged Properties to any of them, the Collateral Agent shall
execute, acknowledge and deliver to the Mortgagor an appropriate instrument
evidencing such release of such Mortgaged Property in such form as may be
reasonably requested by the Mortgagor. The Trustees shall execute, acknowledge
and deliver to the Mortgagor, and the purchaser or other transferee shall be to
rely conclusively on, any such instrument of release of Mortgaged Properties
which bears the signature of the Collateral Agent without any further inquiry.
It is expressly understood that any such release may be delivered to the
Mortgagor prior to the actual sale, transfer or disposition to facilitate such
transaction, provided that such release shall be canceled and redelivered to the
Collateral Agent if such Mortgaged Properties are not so sold, transferred or
disposed of within 20 days after the date such release has been fully executed,
acknowledged and delivered to the Mortgagor. As used herein, the term "Officer's
Certificate" means a certificate signed by the Chairman of the Board, the
President, any Executive Vice President, or the Chief Financial Officer of the
Mortgagor, and the term "Subsidiary" of Borrower means an entity of which more
than 50% of the securities entitled to normal voting power are owned directly,
or indirectly through one or more other Subsidiaries, by Borrower.

         (b) The Trustee and the Collateral Agent shall execute, acknowledge and
deliver to the Mortgagor a termination of this instrument and full release of
all the Mortgaged Properties upon receipt of a notice or other writing signed by
the Administrative Agent under the Primary Credit Agreement, stating that this
instrument is no longer required to be maintained pursuant to the terms of the
Primary Credit Agreement. Such termination of this instrument and full release
of all the Mortgaged Properties shall be evidenced by an instrument in such form
as may be reasonably requested by the Mortgagor, which will be executed,
acknowledged and delivered by the Trustees and the Collateral Agent with
reasonable promptness following receipt of such notice or other writing signed
by the Administrative Agent.

         [6.18 North Dakota Provisions. THE PARTIES AGREE THAT THIS MORTGAGE
CONSTITUTES A COLLATERAL REAL ESTATE MORTGAGE PURSUANT TO NORTH DAKOTA CENTURY
CODE CHAPTER 35-03.]



                              Exhibit Q - Page 21
   74

         [6.19 New Mexico Mortgage. With respect to the Mortgaged Property
located in the State of New Mexico, this Mortgage shall be construed as a
Mortgage and will be subject to foreclosure by law upon, among others, the
occurrence of any event of default.](1)

















- ------------------------
        (1)       To be used in Mortgages to be filed in New Mexico.




                              Exhibit Q - Page 22
   75




         IN WITNESS WHEREOF, the Mortgagor has executed or caused to be executed
this Mortgage, Deed of Trust, Assignment, Security Agreement and Financing
Statement on the day, month and year first above written.

                                           MORTGAGOR


                                           ----------------------------------

                                           By:
                                              -------------------------------
ATTEST:                                    Title:
                                           Printed Name:



- ---------------------
Secretary
Printed Name:





The name and mailing address of the Mortgagor is:


- -------------------
c/o PIONEER NATURAL RESOURCES COMPANY
1400 Williams Square West
5205 North O'Connor Blvd.
Irving, Texas 75039





                       (Signatures Continued on Next Page)





                              Exhibit Q - Page 23
   76



                                      SECURED PARTIES


                                      ----------------------------------------
                                                        , Trustee
                                      ------------------

                                      ----------------------------------------
                                                        , Trustee
                                      ------------------


                                                           , as Collateral Agent
                                      --------------------

                                      By:
                                         -------------------------------------
ATTEST:                               Name:
                                      Printed Name:

- ----------------
Title:
Printed Name:

The names and mailing addresses of the Secured Parties are:

                                        , as Collateral Agent
- ----------------------------------------
                , Trustee and            , Trustee
- ----------------              -----------

- -----------------------------------------

- -----------------------------------------

This Instrument Was Prepared By:

Francis R. Bradley, III, Esq.
Mayer, Brown & Platt
700 Louisiana, Suite 3600
Houston, Texas  77002

[signature]

[SIGNED IN THE PRESENCE OF:


- ----------------
                ]
- ----------------




                              Exhibit Q - Page 24
   77



STATE OF TEXAS                      )
                                    )  Section.
COUNTY OF HARRIS                    )

          BE IT REMEMBERED that I,______________ , a Notary Public duly
qualified, commissioned, sworn and acting in and for the County and State
aforesaid, hereby certify that, on this___day of_____, ______, there appeared
before me severally each of the following persons__________________,
the__________, and _____________ __________, the Secretary, of
_______________________, a _____________, whose address is 1400 Williams Square
West, 5205 North O'Connor Blvd., Irving, Texas 75039.

          [LANGUAGE TO BE INCLUDED ONLY FOR THE APPLICABLE STATES WHERE
                        MORTGAGED PROPERTIES ARE LOCATED]

ALABAMA
  and
MISSISSIPPI                Before me on this day personally appeared the
                           aforementioned persons, whose names are signed to the
                           foregoing conveyance in the capacities set forth
                           opposite the names of such persons above, and who are
                           known to me, acknowledged before me on this day that,
                           being informed of the contents of the conveyance,
                           they, as such officers with full authority, executed
                           the same voluntarily for and as the act of said
                           corporation.

ARKANSAS                   Before me on this day appeared in person the
                           aforementioned persons, to me personally well known,
                           who stated that they held the offices in the
                           corporation set forth opposite their names above and
                           were duly authorized in their respective capacities
                           to execute the foregoing instrument for and in the
                           name and on behalf of said corporation, and further
                           stated and acknowledged that they had so signed,
                           executed and delivered said foregoing instrument for
                           the consideration, uses and purposes therein
                           mentioned and set forth.

COLORADO                   The foregoing instrument was acknowledged before me
                           this day by each such person on behalf of said
                           corporation.

IDAHO                      On this day before me personally appeared the
                           aforementioned persons known or identified to me to
                           be the officers of the corporation that executed the
                           above instrument on behalf of said corporation and
                           acknowledged to me that such corporation executed the
                           same.

ILLINOIS                   The foregoing instrument was acknowledged before me
                           this day by said persons as the designated officers
                           of the corporation set opposite their names on behalf
                           of said corporation.

INDIANA                    Before me this day personally appeared the
                           aforementioned persons who acknowledged the execution
                           of the foregoing instrument.



                              Exhibit Q - Page 25
   78




KANSAS                     This instrument was acknowledged to me on this day by
                           each such person as the designated officer of the
                           corporation set opposite his name, on behalf of said
                           corporation.

KENTUCKY
  and
MICHIGAN                   The foregoing instrument was acknowledged before me
                           this day by said persons as the designated officers
                           of the corporation set opposite their names on behalf
                           of said corporation.

MONTANA                    Before me personally appeared each such person, each
                           of whom is known to me to be the officer of the
                           corporation described in and that executed the within
                           instrument, and acknowledged to me that such
                           corporation executed the same.

NEBRASKA                   The foregoing instrument was acknowledged before me
                           this day by each such person as the designated
                           officers of the corporation set opposite their names
                           on behalf of said corporation.

NEW MEXICO                 The foregoing instrument was acknowledged before me
                           this day by each such person as the designated
                           officer as stated opposite their names of Pogo
                           Producing Company, a Delaware corporation, on behalf
                           of said corporation [in its capacity as general
                           partner of Pogo Gulf Coast, Ltd., a Texas limited
                           partnership, on behalf of said partnership].

NORTH
DAKOTA                     Before me personally appeared each such person, each
                           of whom is known to me to be the officer of the
                           corporation described in and that executed the within
                           instrument, and acknowledged to me that such
                           corporation executed the same.

OHIO                       Before me personally appeared such persons known to
                           me to be the persons who, as the officers of the
                           corporation set opposite their names which executed
                           the foregoing instrument, signed the same, and
                           acknowledged to me that they did so sign said
                           instrument in the name and upon behalf of said
                           corporation as such officers, respectively; that the
                           same is their free act and deed as such officers,
                           respectively, and the free and corporate act and deed
                           of the corporation set opposite their names; that
                           they were duly authorized thereupon by the board of
                           directors of said corporation; and that (as the case
                           may be) the seal affixed to said instrument is the
                           corporate seal of said corporation.

OKLAHOMA                   Before me on this day personally appeared the
                           aforementioned persons, to me known to be the
                           identical persons who subscribed the names of the
                           respective makers thereof to the foregoing instrument
                           in the capacities set forth opposite the names of
                           such persons above, and each such person acknowledged
                           to me that he executed the same as his free and
                           voluntary act and deed and as the free and voluntary
                           act and deed of the corporation set opposite his name
                           for the uses and purposes therein set forth.



                              Exhibit Q - Page 26
   79




SOUTH                      DAKOTA Before me personally appeared each such
                           person, who acknowledged himself to be the designated
                           officer of the corporation set opposite his name, as
                           the case may be, and that as such designated officer
                           being authorized so to do, he executed the foregoing
                           instrument for the purposes therein contained, by
                           signing the name of said corporation by himself as
                           such designated officer.

TEXAS                      This instrument was acknowledged before me on this
                           day by each such person as the designated officer of
                           the corporation set opposite his name on behalf of
                           said corporation set opposite his name.

UTAH                       On this day personally appeared before me such
                           persons, who, being by me duly sworn, did say, that
                           they are the designated officers of said corporation,
                           and that said instrument was signed in behalf of said
                           corporation by resolution of its Board of Directors,
                           and said persons acknowledged to me that the said
                           corporation, executed the same.

WYOMING                    The foregoing instrument was acknowledged before me
                           by the above individuals on this day.

         GIVEN under my hand and seal this___day of_________________.



                                                   ---------------------
                                                   Notary Public in and for
                                                   Harris County, TEXAS


                                                   ---------------------
                                                   Print or Type Name


My commission expires:






                              Exhibit Q - Page 27
   80




STATE OF____          )
                      )  Sections.
COUNTY OF____         )

                  BE IT REMEMBERED that I,______________, a Notary Public duly
qualified, commissioned, sworn and acting in and for the County and State
aforesaid, hereby certify that, on this___day of_________,________, there
appeared before me severally each of the following persons, each being either a
Trustee or else the designated officer of the corporation or association set
opposite his name, and each such Trustee, corporation or association being a
party to the foregoing instrument:

                  _______________,_____________and______,______of____________,
         a______________, whose address is_________________________;

                  __________________and________________whose addresses
         are____________, as Trustees.


          [LANGUAGE TO BE INCLUDED ONLY FOR THE APPLICABLE STATES WHERE
                        MORTGAGED PROPERTIES ARE LOCATED]

ALABAMA
  and
MISSISSIPPI                Before me on this day personally appeared the
                           aforementioned persons, whose names are signed to the
                           foregoing conveyance in the capacities set forth
                           opposite the names of such persons above, and who are
                           known to me, acknowledged before me on this day that,
                           being informed of the contents of the conveyance,
                           they, as such officers or Trustees with full
                           authority, executed the same voluntarily for and as
                           the act of said corporation, said association or said
                           Trustees, as the case may be.

ARKANSAS                   Before me on this day appeared in person the
                           aforementioned persons, to me personally well known,
                           who stated that they held the offices in the
                           corporation or association set forth opposite their
                           names above (or, in the case of the Trustees, were
                           validly appointed Trustees) and were duly authorized
                           in their respective capacities to execute the
                           foregoing instrument for and in the name and on
                           behalf of said corporation or association (or as
                           Trustees, as the case may be), and further stated and
                           acknowledged that they had so signed, executed and
                           delivered said foregoing instrument for the
                           consideration, uses and purposes therein mentioned
                           and set forth.

COLORADO                   The foregoing instrument was acknowledged before me
                           this day by each such person on behalf of said
                           corporation or association, or himself, as Trustee,
                           as the case may be.

IDAHO                      On this day before me personally appeared the
                           aforementioned persons known or identified to me to
                           be the officers (or Trustees, as the case may be) of
                           the





                              Exhibit Q - Page 28
   81

                           corporation or the association that executed the
                           above instrument on behalf of said corporation or
                           association (or themselves, as Trustees) and
                           acknowledged to me that such corporation, association
                           or Trustees executed the same.

ILLINOIS                   The foregoing instrument was acknowledged before me
                           this day by said persons as the designated officers
                           of the corporation or association set opposite their
                           names (or as Trustees, as the case may be) on behalf
                           of said corporation or association (or themselves, as
                           Trustees).

INDIANA                    Before me this day personally appeared the
                           aforementioned persons who acknowledged the execution
                           of the foregoing instrument.

KANSAS                     This instrument was acknowledged to me on this day by
                           each such person as the designated officer of the
                           corporation or association set opposite his name (or
                           a Trustee, as the case may be), on behalf of said
                           corporation or association (or of himself, as a
                           Trustee, as the case may be).

KENTUCKY
  and
MICHIGAN                   The foregoing instrument was acknowledged before me
                           this day by said persons as the designated officers
                           of the corporation or association set opposite their
                           names (or as Trustees, as the case may be) on behalf
                           of said corporation or association (or themselves, as
                           Trustees).

MONTANA                    Before me personally appeared each such person, each
                           of whom is known to me to be the officer of the
                           corporation or association described in and that
                           executed the within instrument (or a Trustee, as the
                           case may be), and acknowledged to me that such
                           corporation or association (or Trustee, as the case
                           may be) executed the same.

NEBRASKA                   The foregoing instrument was acknowledged before me
                           this day by each such person as the designated
                           officers of the corporation or association set
                           opposite their names (or as Trustees, as the case may
                           be) on behalf of said corporation or association, or
                           himself as a Trustee, as the case may be.

NEW MEXICO                 The foregoing instrument was acknowledged before me
                           this day by each such person as the designated
                           officer as stated opposite their
                           names,_____________of, a_______________ on behalf of
                           said___________[(or individually as trustees,
                           residing at _________________as the case may be, on
                           behalf of himself, as a Trustee)] [(or as the
                           designated officer of the Trustee set opposite their
                           respective names, of ___________, a____________,
                           and_____________, a___________, respectively on
                           behalf of said corporation or association, as
                           trustee)].(1)

- ----------------------------
         (1)      Modify as necessary for individual or corporate trustees.


                              Exhibit Q - Page 29
   82



NORTH DAKOTA               Before me personally appeared each such
                           person, each of whom is known to me to be the officer
                           of the corporation or association described in and
                           that executed the within instrument (or a Trustee, as
                           the case may be), and acknowledged to me that such
                           corporation or association (or Trustee, as the case
                           may be) executed the same.

OHIO                       Before me personally appeared such persons known to
                           me to be the persons who, as the officers of the
                           corporation or association set opposite their names
                           which executed the foregoing instrument (or as
                           Trustees, as the case may be), signed the same, and
                           acknowledged to me that they did so sign said
                           instrument in the name and upon behalf of said
                           corporation or association as such officers,
                           respectively (or as Trustees, as the case may be);
                           that the same is their free act and deed as such
                           officers, respectively (or as Trustees as the case
                           may be), and (as the case may be) the free and
                           corporate act and deed of the corporation or
                           association set opposite their names; that (as the
                           case may be) they were duly authorized there unto by
                           the board of directors of said corporation or
                           association; and that (as the case may be) the seal
                           affixed to said instrument is the corporate seal of
                           said corporation or association.

OKLAHOMA                   Before me on this day personally appeared the
                           aforementioned persons, to me known to be the
                           identical persons who subscribed the names of the
                           respective makers thereof to the foregoing instrument
                           in the capacities set forth opposite the names of
                           such persons above, and each such person acknowledged
                           to me that he executed the same as his free and
                           voluntary act and deed and as the free and voluntary
                           act and deed of the corporation or association set
                           opposite his name (or of himself as Trustee, as the
                           case may be) for the uses and purposes therein set
                           forth.

SOUTH                      DAKOTA Before me personally appeared each such
                           person, who acknowledged himself to be the designated
                           officer of the corporation or association set
                           opposite his name, or a Trustee, as the case may be,
                           and that (as the case may be, as such designated
                           officer being authorized so to do) he executed the
                           foregoing instrument for the purposes therein
                           contained, by (as the case may be) signing the name
                           of said corporation or association by himself as such
                           designated officer.

TEXAS                      This instrument was acknowledged before me on this
                           day by each such person as the designated officer of
                           the corporation or association set opposite his name
                           (or a Trustee, as the case may be), on behalf of said
                           corporation or association set opposite his name (or
                           of himself as Trustee, as the case may be).

UTAH                       On this day personally appeared before me such
                           persons, who, being by me duly sworn, did say, that
                           (as the case may be) they are the designated officers
                           of said corporation or association or are Trustees
                           and that said instrument was signed (as the case may
                           be) in behalf of said corporation or association by
                           resolution of its Board of Directors (or on behalf of
                           themselves as Trustees, as the case may be), and said
                           persons acknowledged to me that said corporation,
                           association or Trustees executed the same.




                              Exhibit Q - Page 30
   83

WYOMING                    The foregoing instrument was acknowledged before me
                           by the above individuals on this day.


              GIVEN under my hand and seal this__day of_____________.


                                             -----------------------
                                             Notary Public in and for
                                                         County,
                                             ------------       ---------

                                             ---------------------
                                             Print or Type Name

My commission expires:















                              Exhibit Q - Page 31
   84

                EXHIBIT A To Mortgage, Deed of Trust, Assignment,
                Security Agreement and Financing Statement, dated
                      ______,______, from__________________
                          to___________ and____________
                              and________________,
                               as Collateral Agent

                               List of Properties

                        [to be prepared by the Mortgagor]


         1. Depth limitations, unit designations, unit tract descriptions and
descriptions of undivided leasehold interests, well names, "Operating
Interests", "Working Interests" and "Net Revenue Interests" contained in this
Exhibit A and the listing of any percentage, decimal or fractional interest in
this Exhibit A shall not be deemed to limit or otherwise diminish the interests
being subjected to the lien, security interest and encumbrance of this
instrument.

         2. Some of the land descriptions in this Exhibit A may refer only to a
portion of the land covered by a particular lease. This instrument is not
limited to the land described in Exhibit A but is intended to cover the entire
interest of the Mortgagor in any lease described in Exhibit A even if such
interest relates to land not described in Exhibit A. Reference is made to the
land descriptions contained in the documents of title recorded as described in
this Exhibit A. To the extent that the land descriptions in this Exhibit A are
incomplete, incorrect or not legally sufficient, the land descriptions contained
in the documents so recorded are incorporated herein by this reference.

         3. References in Exhibit A to instruments on file in the public records
are made for all purposes. Unless provided otherwise, all recording references
in Exhibit A are to the official real property records of the county or counties
(or parish or parishes) in which the mortgaged property is located and in which
records such documents are or in the past have been customarily recorded,
whether Deed Records, Oil and Gas Records, Oil and Gas Lease Records or other
records.

         4. A statement herein that a certain interest described herein is
subject to the terms of certain described or referred to agreements, instruments
or other matters shall not operate to subject such interest to any such
agreement, instrument or other matter except to the extent that such agreement,
instrument or matter is otherwise valid and presently subsisting nor shall such
statement be deemed to constitute a recognition by the parties hereto that any
such agreement, instrument or other matter is valid and presently subsisting.



                              Exhibit Q - Page 32
   85



                                   Schedule 1

              Schedule of Lenders' Commitments and Percentage Share



                       Lenders                         Commitment                      Percentage Share
                       -------                         ----------                      ----------------
                                                                                     
NationsBank, N.A.                                    $  178,969,354.90                     13.255320%

CIBC Inc.                                            $  125,077,300.96                      9.263819%

Morgan Guaranty Trust Company of New York            $  178,969,354.95                     13.255320%

Chase Bank of Texas, National Association            $  120,332,991.31                      8.912433%

The Bank of New York                                 $   58,636,363.64                      4.342888%

The Bank of Nova Scotia                              $   96,590,840.62                      7.153976%

Royal Bank of Canada                                 $   96,590,840.62                      7.153976%

Union Bank of California, N.A.                       $   58,636,363.64                      4.342888%

Wells Fargo Bank, N.A.                               $   58,636,363.64                      4.342888%

Bank One, Texas, N.A.                                $   22,872,340.43                      1.694034%

Den Norske Bank ASA                                  $   39,090,909.09                      2.895258%

Paribas                                              $   39,090,909.09                      2.895258%

First Union National Bank                            $   53,323,837.94                      3.949417%

Bankers Trust Company                                $   19,545,454.55                      1.447629%

Credit Agricole Indosuez                             $   19,545,454.55                      1.447629%

Natexis Banque                                       $   19,545,454.55                      1.447629%

Toronto Dominion (Texas), Inc.                       $   52,755,621.88                      3.907332%

The Toyo Trust & Banking Co., Ltd.                   $   19,545,454.55                      1.447629%

Wachovia Bank, N.A.                                  $   33,778,383.40                      2.501788%

The Dai-Ichi Kangyo Bank, Ltd., New York             $   19,545,454.55                      1.447629%
Branch

The Sanwa Bank, Limited                              $   19,545,454.55                      1.447629%

Kredietbank N.V.                                     $   19,545,454.55                      1.447629%
                                                     ===============================================
Totals:                                              $1,350,169,957.96                    100.000000%



                               Schedule 1 - Page 1

   86




                                   Schedule 3

                       Schedule of Restricted Subsidiaries

         This Schedule 3 is attached to and made a part of (i) that certain
Primary Credit Facility pursuant to that certain Second Amended and Restated
Credit Facility Agreement dated as of March 19, 1999 by and among Borrower,
NationsBank, N.A., as Administrative Agent, CIBC Inc., as Documentation Agent,
Morgan Guaranty Trust Company of New York, as Documentation Agent, Chase Bank of
Texas, National Association, as successor-in-interest to The Chase Manhattan
Bank, as Syndication Agent, the Co-Agents party thereto, and the Lenders from
time to time parties thereto, and (ii) that certain 364 Day Credit Facility
pursuant to that certain Second Amended and Restated Credit Facility Agreement
dated as of March 19, 1999 by and among Borrower, NationsBank, N.A., as
Administrative Agent, CIBC Inc., as Documentation Agent, Morgan Guaranty Trust
Company of New York, as Documentation Agent, Chase Bank of Texas, National
Association, as successor-in-interest to The Chase Manhattan Bank, as
Syndication Agent, the Co- Agents party thereto, and the Lenders from time to
time parties thereto.

Pioneer Natural Resources USA, Inc., a Delaware corporation
Pioneer International Resources Company, a Delaware corporation
Pioneer Resources Producing L.P., a Delaware limited partnership
Parker & Parsley (Canada) Petroleum Company, a Nova Scotia, Canada limited
liability company
Pioneer Resources, Inc., , a Delaware corporation
P&PCanada LP Co., a Delaware corporation
Pioneer Natural Resources Canada, Inc., an Alberta,
Canada limited liability company Pioneer Natural Resources (Argentina) S.A., an
Argentina limited liability company
Pioneer Natural Resources (Tierra del Fuego)S.A., an Argentina limited
liability company
Westpan NGL Co., a Delaware corporation
Pioneer Natural Resources (Cayman) Ltd., a Cayman exempted company
Parker & Parsley Petroleum Australia Holdings Pty Limited (A.C.N. 064 589 242),
 a New South Wales, Australia corporation
Parker & Parsley Petroleum Australia Pty Limited (A.C.N. 064 589 180), a New
 South Wales, Australia corporation
Bridge Oil (U.S.A.) Inc., a Delaware corporation



                               Schedule 3 - Page 1

   87




                                   Schedule 4

                              Schedule of Insurance

















                               Schedule 4 - Page 1

   88



                                   Schedule 5

                        Schedule of Security Instruments

Guaranties   -    Pioneer Natural Resources USA, Inc., a Delaware corporation
                  Pioneer International Resources Company, a Delaware
                  corporation
                  Pioneer Resources Producing L.P., a Delaware limited
                  partnership
                  Pioneer Resources, Inc., a Delaware corporation
                  P&PCanada LP Co., a Delaware corporation
                  Pioneer Natural Resources Canada Inc., an Alberta, Canada
                  corporation
                  Westpan NGL Co., a Delaware corporation
                  Pioneer Natural Resources (Argentina) S.A., an Argentina
                  limited liability company
                  Pioneer Natural Resources (Tierra del Fuego) S.A., an
                  Argentina limited liability company

Pledge Agreements or Deeds of Mortgage, Blank Stock Powers and Financing
Statements:

         Pledge Agreement by Pioneer Resources, Inc., a Delaware corporation,
         covering shares of Parker & Parsley (Canada) Petroleum Company, a Nova
         Scotia, Canada limited liability company

         Pledge Agreement by P&PCanada LP Co., a Delaware corporation, covering
         shares of Parker & Parsley (Canada) Petroleum Company, a Nova Scotia,
         Canada limited liability company

         Deed of Mortgage by Pioneer Natural Resources Company USA, Inc., a
         Delaware corporation, covering shares of Parker & Parsley Petroleum
         Australia Holdings Pty. Limited (A.C.N. 064 589 242), a New South
         Wales, Australia corporation

         Pledge Agreement by Pioneer International Resources Company, a Delaware
         corporation, covering shares of Pioneer Natural Resources Canada Inc.,
         an Alberta, Canada limited liability company

         Pledge Agreement by Pioneer Natural Resources USA, Inc., a Delaware
         corporation, covering shares of Pioneer Natural Resources (Cayman)
         Ltd., a Cayman exempted company




                              Schedule 5 - Page 1