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                                                                  EXHIBIT 10.1.3


       SECOND AMENDMENT TO SECOND AMENDED AND RESTATED CREDIT AGREEMENT
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     This Second Amendment to Second Amended and Restated Credit Agreement (this
Second Amendment) is executed as of the 16th day of December, 1999, by and among
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Patina Oil & Gas Corporation, a Delaware Corporation (Borrower), Chase Bank of
                                                      --------
Texas, National Association, as Administrative Agent (Administrative Agent), and
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the financial institutions parties hereto as Banks (individually a Bank and
                                                                   ----
collectively Banks).
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                              W I T N E S E T H:
                              - - - - - - - - -

     WHEREAS, Borrower, Administrative Agent and Banks are parties to that
certain Second Amended and Restated Credit Agreement dated as of July 15, 1999
(as amended, the Credit Agreement) (unless otherwise defined herein, all terms
                 ----------------
used herein with their initial letter capitalized shall have the meaning given
such terms in the Credit Agreement); and

     WHEREAS, pursuant to the Credit Agreement, Banks have made a revolving
credit loan to Borrower; and

     WHEREAS, Borrower has (a) notified Administrative Agent and Banks that
Borrower intends to redeem approximately 565,000 shares of its Original
Preferred Stock, and (b) requested that the Credit Agreement be amended to
revise (i) Section 10.2 thereof as set forth herein in connection therewith, and
(ii) the definition of Restricted Payment Limit as set forth herein.

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

     SECTION 1.  Amendments.  In reliance on the representations, warranties,
     ---------   ----------
covenants and agreements contained in this Second Amendment and subject to the
terms and conditions set forth herein, the Credit Agreement shall be amended
effective as of the date hereof in the manner provided in this Section 1.
                                                               ---------

     1.1.  Amendment to Definitions.  The definitions of Loan Papers and
           ------------------------                      -----------
Restricted Payment Limit contained in Section 2.1 of the Credit Agreement shall
------------------------
be amended to read in full as follows:

           Loan Papers means this Agreement, the First Amendment, the Second
           -----------
     Amendment, the Notes, each Restricted Subsidiary Guarantee now or hereafter
     executed, each Restricted Subsidiary Pledge Agreement now or hereafter
     executed, all Mortgages now or at any time hereafter delivered pursuant to
     Section 6.1, the Collateral Assignment, and all other certificates,
     -----------
     documents or instruments delivered in connection with this Agreement, as
     the foregoing may be amended from time to time.

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          Restricted Payment Limit means as of any date (the measurement date)
          ------------------------                           ----------------
     on and after January 1, 2000, the sum of (i) $10,000,000, plus (ii) an
     amount equal to twenty percent (20%) of Borrower's Consolidated Free Cash
     Flow for the period commencing January 1, 2000 and ending on the last day
     of the Fiscal Quarter most recently ended as of the measurement date for
     which Borrower's consolidated financial statements required by Section
                                                                    -------
     9.1(b) (in the case of the first three quarters of each Fiscal Year, and
     ------
     Section 9.1(a) in the case of the fourth Fiscal Quarter of each Fiscal
     --------------
     Year) have been delivered to Banks.

     1.2. Additional Definitions.  Section 2.1 of the Credit Agreement shall be
          ----------------------
amended to add the following definitions to such Section:

          Second Amendment means the Second Amendment to Second Amended and
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     Restated Credit Agreement dated as of December 16, 1999, entered into by
     and among Borrower, Administrative Agent and Banks.

          Second Qualified Redemption means a one-time redemption by Borrower of
          ---------------------------
     approximately 565,000 shares of the Original Preferred Stock, which
     redemption shall be pursuant to a Second Redemption Notice delivered by
     Borrower not more than ninety (90) days and not less than thirty (30) days
     prior to the fixed date for such redemption.

          Second Redemption Notice means a notice by Borrower to the holders of
          ------------------------
     the Original Preferred Stock, pursuant to which Borrower calls
     approximately 565,000 shares of such Original Preferred Stock for
     redemption.

     1.3. Amendment to Restricted Payments Covenant.  Section 10.2 of the
          -----------------------------------------
Credit Agreement shall be amended to read in full as follows:

          SECTION 10.2.  Restricted Payments.  Neither Borrower nor any
                         -------------------
          Restricted Subsidiary of Borrower will declare or make any Restricted
          Payment; provided, that, so long as no Default, Event of Default or
                   --------  ----
          Borrowing Base Deficiency then exists, and provided that no Default or
          Event of Default would result therefrom, Borrower shall be permitted
          to (a) declare and pay accrued dividends on the Preferred Stock and
          the Common Stock, (b) repurchase any of its Common Stock or Preferred
          Stock or warrants, options or other rights to acquire such Common
          Stock or Preferred Stock, so long as, at any date, the sum of (y) the
          aggregate amount of all such dividends declared and paid pursuant to
          clause (a) above during the period commencing on January 1, 2000 to
          and including such date, plus (z) the aggregate amount paid by
          Borrower and its Restricted Subsidiaries in respect of the repurchase
          of all such Common Stock or Preferred Stock or warrants, options or
          other rights to acquire such Common Stock or Preferred Stock pursuant
          to clause (b) above during the period commencing on January 1, 2000 to
          and including such date, shall not exceed the Restricted Payment Limit
          in effect at such date, and (c) notwithstanding anything to the
          contrary contained herein, consummate and effectuate the Qualified
          Redemption and the Second Qualified Redemption, and neither the
          Qualified Redemption nor the Second Qualified Redemption shall  impact
          or be counted against the Restricted Payment Limit.

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     SECTION 2.  Consent.  Notwithstanding anything to the contrary contained in
     ---------   -------
the Credit Agreement or in any other Loan Paper, Banks hereby (a) consent to the
consummation of the Second Qualified Redemption, and (b) waive any inconsistent
provisions of the Credit Agreement, including, without limitation, Section 10.2
thereof, with respect to the consummation of such Second Qualified Redemption.
The consent and waiver herein contained are expressly limited as follows: (i)
such consent and waiver are limited solely to the consummation of the Second
Qualified Redemption, (ii) such consent and waiver shall not be applicable to
any provision of any Loan Paper other than Section 10.2 of the Credit Agreement,
and (iii) such consent and waiver are each a limited, one-time consent and
waiver, and nothing contained herein shall obligate Banks to grant any
additional or future consent or waiver of, or with respect to, Section 10.2 of
the Credit Agreement or any other provision of any Loan Paper.

     SECTION 3.  Representations and Warranties.  In order to induce
     ---------   ------------------------------
Administrative Agent and Banks to enter into this Second Amendment, Borrower
hereby represents and warrants to Administrative Agent and each Bank that:

     3.1.  Accuracy of Representations and Warranties.  Each representation and
           ------------------------------------------
warranty of Borrower and its Subsidiaries contained in the Loan Papers are true
and correct in all material respects as of the date hereof (except to the extent
that such representations and warranties are expressly made as of a particular
date, in which event such representations and warranties were true and correct
as of such date);

     3.2.  Absence of Defaults.  Neither a Default nor an Event of Default has
           -------------------
occurred which is continuing; and

     3.3.  No Defense.  Borrower has no defenses to payment, counterclaims or
           ----------
rights of set-off with respect to the Obligations on the date hereof.

     SECTION 4.  Miscellaneous.
     ---------   -------------

     4.1.  Reaffirmation of Loan Papers; Extension of Liens.  Any and all of the
           ------------------------------------------------
terms and provisions of the Credit Agreement and the Loan Papers shall, except
as amended and modified hereby, remain in full force and effect.  Borrower
hereby extends the Liens securing the Obligations until the Obligations have
been paid in full, and agrees that the amendments and modifications herein
contained shall in no manner affect or impair the Obligations or the Liens
securing payment and performance thereof.

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

     4.3.  Counterparts.  This Second Amendment may be executed in counterparts,
           ------------
and all parties need not execute the same counterpart; however, no party shall
be bound by this Second Amendment until this Second Amendment has been executed
by Borrower, Administrative Agent and Required Banks at which time this Second
Amendment shall be binding on, enforceable against and inure to the benefit of
Borrower, Administrative Agent and all Banks.  Facsimiles shall be effective as
originals.

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     4.4.  COMPLETE AGREEMENT.  THIS SECOND AMENDMENT, THE CREDIT AGREEMENT AND
           ------------------
THE OTHER LOAN PAPERS REPRESENT THE FINAL AGREEMENT AMONG THE PARTIES AND MAY
NOT BE CONTRADICTED BY EVIDENCE OF PRIOR, CONTEMPORANEOUS OR ORAL AGREEMENTS OF
THE PARTIES.  THERE ARE NO UNWRITTEN ORAL AGREEMENTS BETWEEN THE PARTIES.

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

     4.6.  Legal Expenses.  Borrower hereby agrees to pay on demand all
           --------------
reasonable fees and expenses of counsel to Administrative Agent incurred by
Administrative Agent in connection with the preparation, negotiation and
execution of this Second Amendment and all related documents.

     IN WITNESS WHEREOF, the parties hereto have caused this Second Amendment to
be duly executed by their respective Authorized Officers on the date and year
first above written.

                           [Signature Pages Follow]

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SIGNATURE PAGE  TO SECOND AMENDMENT TO SECOND AMENDED AND RESTATED CREDIT
AGREEMENT DATED AS OF DECEMBER 16, 1999, BY AND AMONG PATINA OIL & GAS
CORPORATION, AS BORROWER, THE FINANCIAL INSTITUTIONS PARTIES THERETO, AS BANKS,
AND CHASE BANK OF TEXAS, NATIONAL ASSOCIATION, AS ADMINISTRATIVE AGENT


                                    PATINA OIL & GAS CORPORATION

                                    By:  /s/ David J. Kornder
                                         -------------------------------------
                                         David J. Kornder, Vice President and
                                         Chief Financial Officer


                                    CHASE BANK OF TEXAS, NATIONAL
                                    ASSOCIATION, as Administrative Agent

                                    By:  /s/ Robert C. Mertensotto
                                         -------------------------------------
                                         Robert C. Mertensotto,
                                         Managing Director



                                    CHASE BANK OF TEXAS, NATIONAL
                                    ASSOCIATION, as a Bank

                                    By:  /s/ Robert C. Mertensotto
                                         -------------------------------------
                                         Robert C. Mertensotto,
                                         Managing Director


                                    BANK OF AMERICA, N.A., as a Bank

                                    By:  /s/ J. Scott Fowler
                                         -------------------------------------
                                         J. Scott Fowler, Managing Director


                                    BANK ONE, NA
                                    (MAIN OFFICE - CHICAGO) as a Bank
                                    (FORMERLY KNOWN AS THE FIRST
                                    NATIONAL BANK OF CHICAGO)

                                    By:  /s/ Tim Merrell
                                         -------------------------------------
                                         Tim Merrell, Vice President

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SIGNATURE PAGE  TO SECOND AMENDMENT TO SECOND AMENDED AND RESTATED CREDIT
AGREEMENT DATED AS OF DECEMBER 16, 1999, BY AND AMONG PATINA OIL & GAS
CORPORATION, AS BORROWER, THE FINANCIAL INSTITUTIONS PARTIES THERETO, AS BANKS,
AND CHASE BANK OF TEXAS, NATIONAL ASSOCIATION, AS ADMINISTRATIVE AGENT


                                    BANKERS TRUST COMPANY, as a Bank

                                    By:  /s/ Marcus M. Tarkington
                                         ---------------------------------------
                                         Marcus M. Tarkington, Principal



                                    CREDIT LYONNAIS NEW YORK BRANCH

                                    By:  /s/ Phillipe Soustra
                                         ---------------------------------------
                                         Phillipe Soustra, Senior Vice President



                                    FIRST UNION NATIONAL BANK

                                    By:  /s/ Robert R. Wetteroff
                                         ---------------------------------------
                                         Robert R. Wetteroff, Senior V.P.



                                    WELLS FARGO BANK, N.A.

                                    By:  /s/ Greg Petruska
                                         ---------------------------------------
                                         Greg Petruska, Vice President

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