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                                                                   Exhibit 10.19

                              THIRD AMENDMENT OF
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                     AMENDED AND RESTATED CREDIT AGREEMENT
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               THIS THIRD AMENDMENT OF AMENDED AND RESTATED CREDIT AGREEMENT
(this "Amendment"), dated as of December 1, 1999, is by and among BASIN
EXPLORATION, INC., a Delaware corporation ("Borrower"), U.S. BANK NATIONAL
ASSOCIATION f/k/a COLORADO NATIONAL BANK ("USB"), UNION BANK OF CALIFORNIA, N.A.
("Union"), TORONTO DOMINION (TEXAS), INC. ("TDT"), and BANK OF AMERICA, N.A., a
national banking association ("BA"), in its capacity as a Lender and as Agent
for Lenders. USB, Union, TDT and BA are herein collectively referred to as
"Lenders."

                                   RECITALS

               A. Borrower and NationsBank, USB and Union entered into an
Amended and Restated Credit Agreement dated as of January 1, 1999, as previously
amended (as so amended, the "Credit Agreement"), in order to set forth the terms
upon which NationsBank, USB and Union would make loans to Borrower and issue
letters of credit at the request of Borrower and by which such loans and letters
of credit would be governed and repaid. Capitalized terms used herein without
definition shall have the same meanings as set forth in the Credit Agreement.

               B. The parties hereto wish to enter into this Amendment in order
to amend certain terms and provisions of the Credit Agreement.

                                   AGREEMENT

               NOW, THEREFORE, in consideration of $10.00 and other good and
valuable consideration, the receipt and sufficiency of which are hereby
acknowledged, the parties hereby agree as follows:

               1.   Credit Agreement. Effective as of the date of this
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Amendment, the Credit Agreement shall be, and hereby is, amended as follows:

                    (a)  The definition of "Borrowing Base (Conforming)" in
Section 1.1 on page 3 of the Credit Agreement shall be deleted, and the
following shall be substituted therefor:

                              "Borrowing Base (Conforming)" means, at any
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          time prior to the Maturity Date, that portion of the Borrowing
          Base attributable to Facility A, which shall be the aggregate
          loan value of all Borrowing Base Properties, as determined by
          Lenders in their sole and absolute discretion, in accordance with
          the procedures for conforming oil and gas borrowing base loans
          set forth in Section 3.2 below; provided that
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          the Borrowing Base (Conforming) for the time period from December
          1, 1999 through the next determination of the Borrowing Base
          (Conforming) by Lenders shall be $90,000,000.

                    (b)  The definition of "Revolving Period" in Section 1.1 on
page 13 of the Credit Agreement shall be deleted, and the following shall be
substituted therefor:

                              "Revolving Period" means the time period from
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          the date of this Agreement through November 30, 2002; provided
          that, upon the request of Borrower, Lenders may, in their sole
          discretion, extend such time period at any time and from time to
          time to a date not later than December 31, 2006 by giving written
          notice of such extension to Borrower, but nothing contained in
          this Agreement, the Notes or any other Loan Document shall be
          deemed to commit or require Lenders to agree to any such
          extension.

                    (c)  The following new Section 8.10 shall be inserted
immediately after the end of Section 8.9 on page 56 of the Credit Agreement:

                              Section 8.10.  Funding. Unless Borrower or
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          any Lender has notified Agent prior to the date any payment to be
          made by it is due, that it does not intend to remit such payment,
          Agent may, in its sole discretion, assume that Borrower or said
          Lender, as the case may be, has timely remitted such payment and
          may, in its sole and absolute discretion and in reliance thereon,
          make available such payment to the Person entitled thereto. If
          such payment was not in fact remitted to Agent in immediately
          available funds, then:

                                   (a)  If Borrower has failed to make such
          payment, each Lender shall forthwith on demand repay to Agent the
          amount of such assumed payment made available to such Lender,
          together with interest thereon in respect of each day from and
          including the date such amount was made available by Agent to
          such Lender to the date such amount is repaid to Agent at the
          Federal Funds Rate;

                                   (b)  If any Lender has failed to make
          such payment, Agent shall be entitled to recover such
          corresponding amount on demand from such Lender. If such Lender
          does not pay such corresponding amount forthwith upon Agent's
          demand therefor, Agent shall promptly notify Borrower, and
          Borrower shall pay such corresponding amount to Agent. Agent
          shall also be entitled to recover from such Lender interest on
          such

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          corresponding amount in respect of each day from and including
          the date such corresponding amount was made available by Agent to
          Borrower to the date such corresponding amount is recovered by
          Agent: (1) from such Lender at a rate per annum equal to the
          daily Federal Funds Rate, and (2) from Borrower, at a rate per
          annum equal to the interest rate applicable to such borrowing.
          Nothing herein shall be deemed to relieve any Lender from its
          obligation to fulfill its Commitment or to prejudice any rights
          which Agent or Borrower may have against any Lender as a result
          of any default by such Lender hereunder.

               2.   Loan Documents. All references in any document to the
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Credit Agreement shall refer to the Credit Agreement, as amended pursuant
to this Amendment.

                3.  Representations and Warranties. Borrower hereby certifies to
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Lenders that as of the date of (and after giving effect to) this Amendment,
except as heretofore disclosed to and waived by Lenders: (a) all of Borrower's
representations and warranties contained in the Credit Agreement are true,
accurate and complete in all material respects, and (b) no Default or Event of
Default has occurred and is continuing under the Credit Agreement.

                4.  Continuation of the Credit Agreement. Except as specified in
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this Amendment, the provisions of the Credit Agreement shall remain in full
force and effect, and if there is a conflict between the terms of this Amendment
and those of the Credit Agreement, the terms of this Amendment shall control.
Borrower hereby ratifies, confirms and adopts the Credit Agreement, as amended
hereby.

                5.  Expenses. Borrower shall pay all reasonable expenses
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incurred in connection with the transactions contemplated by this Amendment,
including without limitation all reasonable fees and reasonable expenses of
Lenders' attorneys and all recording and filing fees, charges and expenses.

                6.  Miscellaneous.  This Amendment shall be governed by and
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construed under the laws of the State of Colorado and shall be binding upon and
inure to the benefit of the parties hereto and their successors and assigns.
This Amendment and any and all documents to be delivered in connection herewith
may be executed in any number of counterparts, each of which shall be an
original, but all of which together shall constitute one instrument. Delivery of
this Amendment and any and all documents to be delivered in connection herewith
by any party may be effected, without limitation, by faxing a signed counterpart
of the signature page of this Amendment to BA, in care of David G. Stolfa, Esq.
(303-762-9992), (any party that effects delivery in such manner hereby agreeing
to transmit promptly to BA, in care of David G. Stolfa, Esq., an actual signed
counterpart).

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               EXECUTED as of the date first above written.

                              BASIN EXPLORATION, INC.


                              By: ___________________________________
                                  Vice President/Chief Financial
                                   Officer

                              BANK OF AMERICA, N.A., in its capacity as a
                                 Lender and as Agent for Lenders

                              By: ___________________________________
                                  Principal

                              U.S. BANK NATIONAL ASSOCIATION


                              By: ___________________________________
                                  Vice President

                              UNION BANK OF CALIFORNIA, N.A.


                              By: ___________________________________
                                  Vice President


                              By: ___________________________________
                                  Vice President

                              TORONTO DOMINION (TEXAS), INC.


                              By: ___________________________________
                                  Vice President

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