EXHIBIT 10.37.11


                      FOURTH AMENDMENT TO CREDIT AGREEMENT

         THIS FOURTH AMENDMENT TO CREDIT AGREEMENT ("Amendment") is entered into
as of February 14,2003, by and among BLACK WARRIOR WIRELINE CORP., a Delaware
corporation ("Borrower"), the other Credit Parties signatory hereto and GENERAL
ELECTRIC CAPITAL CORPORATION, a Delaware corporation ("GE Capital"), for itself,
as Lender, and as Agent for Lenders (in such capacity, the "Agent").

                                    RECITALS

A. Borrower, the other Credit Parties signatory thereto, GE Capital, the other
Lenders signatory thereto from time to time and the Agent are parties to a
certain Credit Agreement dated as of September 14, 2001, as amended by that
certain First Amendment to Credit Agreement, dated as of January 26, 2002, as
amended by that certain Second Amendment to Credit Agreement, dated as of June
10, 2002 and as amended by that certain Third Amendment to Credit Agreement,
dated as of October 31, 2002 (the "Credit Agreement;" capitalized terms used
herein and not defined herein have the meanings assigned to them in the Credit
Agreement).

B. Borrower has requested that the Lenders amend the Credit Agreement in certain
respects and the Lenders have agreed to amend the Credit Agreement, subject to
the terms and conditions hereof.

NOW, THEREFORE, in consideration of the premises and the mutual covenants
hereinafter contained, and intending to be legally bound, the parties hereto
agree as follows:

A. AMENDMENT

1. Amendment to Section 1.6 of the Credit Agreement. The Credit Agreement is
hereby amended by deleting Section 1.6(l) of the Credit Agreement and by
substituting in lieu thereof the following:

         (l) that is in default; provided, that, without limiting the generality
of the foregoing, an Account shall be deemed in default upon the occurrence of
any of the following:

the Account is not paid within the earlier of: 60 days following its due date or
90 days following its original invoice date; provided that any Account with
respect to Chevron USA, Exxon USA, Unocal Gulf Region USA, Masters Resources LLC
and Encore

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Operating shall be in default if not paid within the earlier of 120 days
following its due date or 120 days following its original invoice date; the
Account Debtor obligated upon such Account suspends business, makes a general
assignment for the benefit of creditors or fails to pay its debts generally as
they come due; or a petition is filed by or against any Account Debtor obligated
upon such Account under any bankruptcy law or any other federal, state or
foreign (including any provincial) receivership, insolvency relief or other law
or laws for the relief of debtors;

B. REPRESENTATIONS

Each Credit Party hereby represents and warrants to the Lenders and the Agent
that:

1. The execution, delivery and performance by such Credit Party of this
Amendment (a) are within such Credit Party's corporate power; (b) have been duly
authorized by all necessary corporate and shareholder action; (c) are not in
contravention of any provision of such Credit Party's certificate of
incorporation or bylaws or other organizational documents; (d) do not violate
any law or regulation, or any order or decree of any Governmental Authority; (e)
do not conflict with or result in the breach or termination of, constitute a
default under or accelerate any performance required by, any indenture,
mortgage, deed of trust, lease, agreement or other instrument to which such
Credit Party or any of its Subsidiaries is a party or by which such Credit Party
or any such Subsidiary or any of their respective property is bound; (f) do not
result in the creation or imposition of any Lien upon any of the property of
such Credit Party or any of its Subsidiaries; and (g) do not require the consent
or approval of any Governmental Authority or any other person;

2. This Amendment has been duly executed and delivered for the benefit of or on
behalf of each Credit Party and constitutes a legal, valid and binding
obligation of each Credit Party, enforceable against such Credit Party in
accordance with its terms except as the enforceability hereof may be limited by
bankruptcy, insolvency, reorganization, moratorium and other laws affecting
creditors' rights and remedies in general; and

3. After giving effect to this Amendment, no Default or Event of Default has
occurred and is continuing as of the date hereof.

C. OTHER AGREEMENTS

         1. Continuing Effectiveness of Loan Documents. As amended hereby, all
terms of the Credit Agreement and the other Loan Documents shall be and remain
in full force and effect and shall constitute the legal, valid, binding and
enforceable obligations of Borrower. To the extent any terms and conditions in
any of the other Loan Documents shall contradict or be in conflict with any
terms or conditions of the Credit Agreement, after giving effect to this
Amendment, such terms and conditions are hereby deemed modified and amended
accordingly to reflect the terms and conditions of the Credit Agreement as
modified and amended hereby. Upon the effectiveness of this Amendment

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such terms and conditions are hereby deemed modified and amended accordingly to
reflect the terms and conditions of the Credit Agreement as modified and amended
hereby.

         2. Reaffirmation. Borrower hereby restates, ratifies and reaffirms each
and every term and condition set forth in the Credit Agreement and the other
Loan Documents, effective as of the date hereof and after giving effect to this
Amendment, and represents that, after giving effect to this Amendment, no
Default or Event of Default has occurred and is continuing as of the date
hereof.

         3. Expenses. Borrower agrees to pay on demand all costs and expenses of
Agent in connection with the preparation, execution, delivery and enforcement of
this Amendment, the closing hereof, and any other transactions contemplated
hereby, including the fees and out-of-pocket expenses of Agent's counsel.

         4. Governing Law. IN ALL RESPECTS, INCLUDING ALL MATTERS OF
CONSTRUCTION, VALIDITY AND PERFORMANCE, THIS AMENDMENT SHALL BE GOVERNED BY, AND
CONSTRUED AND ENFORCED IN ACCORDANCE WITH, THE INTERNAL LAWS OF THE STATE OF NEW
YORK APPLICABLE TO CONTRACTS MADE AND PERFORMED IN THAT STATE AND ANY APPLICABLE
LAWS OF THE UNITED STATES OF AMERICA.


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         IN WITNESS WHEREOF, this Amendment has been duly executed as of the
date first written above.

BLACK WARRIOR WIRELINE CORPORATION, as Borrower
By:

Name:    William L. Jenkins
Title:   Chief Executive Officer

GENERAL ELECTRIC CAPITAL CORPORATION, as Agent and Lender

By:
         John Hanley

                                                     Duly Authorized Signatory