FIRST AMENDMENT OF
                      AMENDED AND RESTATED CREDIT AGREEMENT

     THIS FIRST AMENDMENT OF AMENDED AND RESTATED CREDIT AGREEMENT (this
"Amendment"), dated as of June 11, 1997, is by and among BASIN EXPLORATION,
INC., a Delaware corporation ("Borrower"), COLORADO NATIONAL BANK ("CNB"), UNION
BANK OF CALIFORNIA, N.A. ("Union"), and NATIONSBANK OF TEXAS, N.A. ("NBT"), in
its capacity as a Lender and as Agent for Lenders. CNB, Union and NBT are herein
collectively referred to as "Lenders."

                                    RECITALS

     A. Borrower and Lenders entered into an Amended and Restated Credit
Agreement dated as of August 6, 1996 (the "Credit Agreement'), in order to set
forth the terms upon which Lenders 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. 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 Amendment, the Credit
Agreement shall be, and hereby is, amended as follows:

     (a) The following new definitions shall be inserted in proper alphabetical
order in Section 1.1 of the Credit Agreement:

          "REGULAR BORROWING BASE" means, at any time during the time period
     from June 12, 1997 to the date as of which the November 1, 1997
     redetermination of the Borrowing Base becomes effective, $25,000,000,
     unless Borrower and Lenders hereafter mutually agree upon a different
     amount.

          "SUPPLEMENTAL BORROWING BASE" means, at any time during the time
     period from June 12, 1997 to the date as of which the November 1, 1997
     redetermination of the Borrowing Base becomes


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     effective, the excess of the Borrowing Base over the Regular Borrowing
     Base.

     (b) The definition of "Base Rate Spread" in Section 1.1 on page 1 of the
Credit Agreement shall be deleted, and the following shall be substituted
therefor:

          "BASE RATE SPREAD" means: (a) for any and all calendar months that the
     Capitalization Ratio is greater than or equal to 50 percent, 0.25
     percentage points per annum; and (b) for any and all calendar months that
     the Capitalization Ratio is less than 50 percent, 0.00 percentage points
     per annum; provided that, as to any time period during which the
     then-outstanding principal balance of the Loan plus the face amount of all
     Letters of Credit outstanding hereunder exceeds the Regular Borrowing Base,
     the amount set forth in clause (a) above shall be increased to 0.75
     percentage points per annum and the amount set forth in clause (b) above
     shall be increased to 0.50 percentage points per annum.

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

          "BORROWING BASE" means, at any time, the aggregate loan value of the
     Borrowing Base Properties, as determined by Lenders in accordance with the
     provisions of Section 3.2 below; provided that, for the time period from
     the date of this Agreement through June 11, 1997, the Borrowing Base shall
     be $25,000,000; provided further that, for the time period from June 12,
     1997 to the date as of which the November 1, 1997 redetermination of the
     Borrowing Base becomes effective, the Borrowing Base shall be $32,500,000
     unless Borrower and Lenders hereafter mutually agree upon a different
     amount or unless the Borrowing Base is redetermined pursuant to Section 3.2
     below prior to such redetermination date.

     (d) The definition of "Fixed Rate Spread" in Section 1.1 on page 7 of the
Credit Agreement shall be deleted, and the following shall be substituted
therefor:

          "FIXED RATE SPREAD" means: (a) for any and all calendar months that
     the Capitalization Ratio is greater than or equal to 50 percent, 1.25
     percentage points per annum; (b) for any and all calendar months that the
     Capitalization Ratio is less than 50 percent but greater than or equal to
     40 percent, 1.00 percentage point per annum; (c) for any

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     and all calendar months that the Capitalization Ratio is less than 40
     percent but greater than or equal to 30 percent, 0.75 percentage point per
     annum; and (d) for any and all calendar months that the Capitalization
     Ratio is less than 30 percent, 0.625 percentage point per annum; provided
     that, as to any time period during which the then-outstanding principal
     balance of the Loan plus the face amount of all Letters of Credit
     outstanding hereunder exceeds the Regular Borrowing Base, the amount set
     forth in clause (a) above shall be increased to 1.75 percentage points per
     annum, the amount set forth in clause (b) above shall be increased to 1.50
     percentage points per annum, the amount set forth in clause (c) above shall
     be increased to 1.25 percentage points per annum and the amount set forth
     in clause (d) above shall be increased to 1.125 percentage points per
     annum.

     (e) Section 3.6(a) on pages 22 and 23 of the Credit Agreement shall be
deleted, and the following shall be substituted therefor:

          Section 3.6. FEES. (a) Borrower shall pay to Agent, on behalf of
     Lenders (and Agent shall pay each Lender its respective Proportionate Share
     thereof on the Business Day that any such payment is deemed to be received
     from Borrower), within 30 days after the end of each three-month period
     ending on the last day of January, April, July or October during the
     Revolving Period, commencing with the three-month period ending October 31,
     1996, a commitment fee, computed on a daily basis for such three-month
     period, in an amount equal to: (i) the Commitment Fee Rate, times (ii) the
     excess of the Commitment Amount over the sum of the outstanding principal
     balance of the Loan plus the face amount of all Letters of Credit
     outstanding hereunder; provided that, for the time period from June 12,
     1997 to the date as of which the November 1, 1997 redetermination of the
     Borrowing Base becomes effective, such fee shall be calculated as follows:
     (1)(A) the Commitment Fee Rate, times (B) the excess of the Regular
     Borrowing Base over the sum of the outstanding principal balance of the
     Loan plus the face amount of all Letters of Credit outstanding hereunder;
     plus (2) (A) 0.625 percentage points per annum, times (B) the excess of the
     Commitment Amount over the greater of: (I) the sum of the outstanding
     principal balance of the Loan plus the face amount of all Letters of Credit
     outstanding hereunder; or (II) the Regular Borrowing Base.


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     (f) The next-to-last sentence of Section 5.1(m) on page 30 of the Credit
Agreement shall be amended to read as follows: "Borrower has no subsidiaries
other than Basin Offshore Oil & Gas, Inc., wholly-owned subsidiary."

     (g) In Borrower's address in Section 9.3 on page 53 of the Credit
Agreement, "Suite 1800" shall be changed to "Suite 3400".

     (h) At the end of the paragraph numbered 4 on the Disclosure Schedule
(Schedule 2 of the Credit Agreement), the following shall be inserted: "On or
about August 31, 1996, a partial plan termination relating to accelerated
vesting occurred with respect to Borrower's 401(k) plan."

     2. LOAN DOCUMENTS. All references in any document to the Credit Agreement
shall refer to the Credit Agreement, as amended and supplemented pursuant to
this Amendment.

     3. CONDITIONS PRECEDENT. The obligations of the parties under this
Amendment are subject, at the option of Lenders, to the prior satisfaction of
the condition that Borrower shall have executed and/or delivered, or caused to
have been executed and/or delivered, to or for the benefit of Lenders, the
following (all documents to be satisfactory in form and substance to Lenders):

     (a) This Amendment.

     (b) Such certificates of officers of Borrower as may be required by
Lenders.

     (c) Any and all other Loan Documents required by Lenders.

     4. REPRESENTATIONS AND WARRANTIES. Borrower hereby certifies to 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.

     5. CONTINUATION OF THE CREDIT AGREEMENT. Except as specified in 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.

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     6. EXPENSES. Borrower shall pay all reasonable expenses 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.

     7. MISCELLANEOUS. This Amendment shall be governed by and 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
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 this Amendment to NBT (any party that effects delivery in such manner hereby
agreeing to transmit promptly to NBT an actual signed counterpart).

     EXECUTED as of the date first above written.

                        BASIN EXPLORATION, INC.


                        By:  /s/ NEIL L. STENBUCK
                             ----------------------------------------
                             Vice President/Chief Financial
                             Officer

                        COLORADO NATIONAL BANK


                        By:  /s/ KATHRYN A. GAITER
                             ----------------------------------------
                             Vice President

                        NATIONSBANK OF TEXAS, N.A., in its
                        capacity as a Lender and as Agent
                        for Lenders


                        By:  /s/ DAVID A. RUBENKING
                             ----------------------------------------
                             Senior Vice President

                        UNION BANK OF CALIFORNIA, N.A.


                        By  /s/  RANDALL L. OSTERBERG
                            -----------------------------------------
                            Vice President


                        By  /s/ MICHAEL E. TREGONING
                            -----------------------------------------
                            Senior Vice President



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