<PAGE>

                                                                 EXHIBIT 10.8(a)


            FIRST AMENDMENT TO AMENDED AND RESTATED CREDIT AGREEMENT

         This FIRST AMENDMENT TO AMENDED AND RESTATED CREDIT AGREEMENT, dated as
of August 26, 2003 (this "Amendment"), is made by and among W-H ENERGY SERVICES,
INC., a Texas corporation (the "Borrower"), the various financial institutions
(collectively, the "Lenders") parties to the Credit Agreement (defined below)
which are parties hereto, CREDIT SUISSE FIRST BOSTON, acting through its Cayman
Islands branch ("CSFB"), as syndication agent, sole lead arranger and sole book
running manager (collectively the "Syndication Agent") for the Lenders under the
Credit Agreement, BANK ONE, NA, as documentation agent for the Lenders under the
Credit Agreement (in such capacity, the "Documentation Agent"), and WELLS FARGO
BANK TEXAS, N.A., as the administrative agent for the Lenders under the Credit
Agreement (in such capacity, the "Administrative Agent").

                                   WITNESSETH:

         WHEREAS, the Borrower, the Lenders, the Syndication Agent, the
Administrative Agent and the Documentation Agent have heretofore entered into
the Amended and Restated Credit Agreement, dated as of May 31, 2001 (as amended,
amended and restated, supplemented, or otherwise modified from time to time
prior to the date hereof, the "Credit Agreement");

         WHEREAS, the Borrower has requested the Lenders amend certain
provisions of the Credit Agreement and extend additional Commitments to make
Term Loans in an amount not to exceed $70,000,000 (the "Term C Loans"); and

         WHEREAS, the parties hereto are willing to consent to such amendments
and certain Lenders are willing to extend Commitments to make Term C Loans on
the terms and subject to the conditions of this Amendment (the Credit Agreement,
as amended pursuant to the terms of this Amendment, being referred to as the
"Amended Credit Agreement");

         NOW, THEREFORE, in consideration of the premises and the mutual
agreements herein contained, the parties hereto agree as follows:

                                   ARTICLE I

                                   DEFINITIONS

         Unless otherwise defined or the context otherwise requires, terms for
which meanings are provided in the Credit Agreement shall have such meanings
when used in this Amendment.

<PAGE>

                                   ARTICLE II

                     CONSENT; AMENDMENTS TO CREDIT AGREEMENT

         Subject to the conditions and on the terms set forth herein (including
satisfaction or waiver of the conditions set forth in Article III), and in
reliance on the representations and warranties of the Borrower contained herein,
(i) notwithstanding the application provisions of clause (b) of Section 3.1.2 of
the Credit Agreement, each of the requisite Lenders hereby consents to and
otherwise ratifies, approves and confirms in each and every respect the
Borrower's use of a portion of the proceeds from the issuance of the Term C
Loans to make a voluntary prepayment on the First Amendment Effective Date
(defined below) of outstanding Term A Loans in an aggregate amount of up to
$11,000,000, in direct order of maturity on a pro rata basis as among the
Lenders holding Term A Loans and (ii) the parties hereto agree that the Credit
Agreement is hereby amended, as of the date hereof, in accordance with this
Article II; except as so consented to and amended, the Credit Agreement shall
continue in full force and effect.

         SECTION 2.1. Amendments to Section 1.1.

         SECTION 2.1.1. Addition of Certain Definitions to Section 1.1. Section
1.1 of the Credit Agreement is hereby amended by inserting the following
definitions in such Section in the appropriate alphabetical sequence:

                  "First Amendment" means the First Amendment to Amended and
         Restated Credit Agreement, dated as of August 26, 2003, by and among
         the Borrower, the Agents and the Lenders party thereto.

                  "First Amendment Effective Date" is defined in Article III of
         the First Amendment.

                  "Term C Loan" is defined in Section 2.1.1(e).

                  "Term C Loan Commitment" is defined in Section 2.1.1(e).

                  "Term C Loan Commitment Amount" means $70,000,000.

                  "Term C Loan Commitment Termination Date" means the earliest
         of:

                           (a) August 26, 2003 (if the Term C Loans have not
                  been made on or prior to such date);

                           (b) the First Amendment Effective Date (immediately
                  after the making of the Term C Loans on such date); and

                           (c) the date on which any Commitment Termination
                  Event occurs.

                  "Term C Note" means a promissory note of the Borrower payable
         to any Lender, in the form of Exhibit B-3 hereto with respect to any
         such note issued on or subsequent to the First Amendment Effective Date
         (as such promissory note may be amended, endorsed or otherwise modified
         from time to time), evidencing the aggregate Indebtedness of the
         Borrower to such Lender resulting from its outstanding Term C Loans,
         and also means all



                                       2
<PAGE>

         other promissory notes accepted from time to time in substitution
         therefor or renewal thereof.

         SECTION 2.1.2. Amendment to Definition of "Applicable Margin". The
definition of "Applicable Margin" is hereby amended by relettering clause (b)
thereof as a new clause (c) and inserting the following new clause (b) in
substitution therefor:

                  "(b) with respect to the unpaid principal amount of each Term
         C Loan maintained as (i) a Base Rate Loan, 2.00% per annum and (ii) a
         LIBO Rate Loan, 3.00% per annum; and".

         SECTION 2.1.3. Amendment and Restatement of Certain Definitions Set
Forth in Section 1.1. Each of the following definitions of the Credit Agreement
is hereby amended and restated to read in its entirety as follows:

                  "Borrower Security Agreement" means the Amended and Restated
         Security Agreement executed and delivered by an Authorized Officer of
         the Borrower pursuant to Section 3.7 of the First Amendment, amending
         and restating the Borrower Security Agreement delivered pursuant to
         Section 5.1.9 of the Existing Credit Agreement, together with any
         supplements thereto delivered pursuant to the terms of this Agreement,
         in each case as amended, supplemented, amended and restated or
         otherwise modified from time to time.

                  "Commitment" means, as the context may require, (a) a Lender's
         Term C Loan Commitment, Revolving Loan Commitment or Letter of Credit
         Commitment or (b) the Swing Line Lender's Swing Line Loan Commitment.

                  "Commitment Amount" means, as the context may require, the
         Term C Loan Commitment Amount, the Revolving Loan Commitment Amount,
         the Letter of Credit Commitment Amount or the Swing Line Loan
         Commitment Amount.

                  "Commitment Termination Date" means, as the context may
         require, the Revolving Loan Commitment Termination Date or the Term C
         Loan Commitment Termination Date.

                  "Loan" means, as the context may require, a Revolving Loan, a
         Term Loan or a Swing Line Loan of any type.

                  "Note" means, as the context may require, a Revolving Note, a
         Term A Note, a Term B Note, a Term C Note or a Swing Line Note, or a
         corresponding recordation on the Register.

                  "Percentage" means, relative to any Lender with respect to any
         Loans, the applicable percentage relating thereto set forth opposite
         such Lender's name on Schedule II hereto; provided, however, that, in
         each case, "Percentage" shall also include, relative to any Lender, the
         applicable percentage relating to Revolving Loans, Term A Loans, Term B
         Loans or Term C Loans, as the case may be, as set forth in the Lender
         Assignment Agreement pursuant to which such Lender became a Lender
         hereunder, as such percentage may be adjusted from time to time
         pursuant to Lender Assignment Agreement(s) executed by such Lender and
         its Assignee Lender(s) and delivered



                                       3
<PAGE>

         pursuant to Section 10.11 or (in the case of Revolving Loans, Term A
         Loans or Term B Loans) pursuant to Section 2.2.2. A Lender shall not
         have any Commitment to make Revolving Loans, Term A Loans, Term B Loans
         or Term C Loans if its Percentage under the respective column heading
         is zero.

                  "Stated Maturity Date" means

                       (a)  in the case of any Revolving Loan, October 16, 2005;

                       (b)  in the case of any Term A Loan, October 16, 2005;

                       (c)  in the case of any Term B Loan, April 16, 2007; and

                       (d)  in the case of any Term C Loan, April 16, 2007.

                  "Subsidiary Security Agreement" means the Amended and Restated
         Security Agreement executed and delivered by an Authorized Officer of
         each Subsidiary Guarantor pursuant to Section 3.7 of the First
         Amendment, amending and restating the Subsidiary Security Agreement
         delivered pursuant to Section 5.1.9 of the Existing Credit Agreement,
         together with any supplements thereto delivered pursuant to the terms
         of this Agreement, in each case as amended, supplemented, amended and
         restated or otherwise modified from time to time.

                  "Term Loans" means, collectively, the Term A Loans, the Term B
         Loans and the Term C Loans.

                  "Tranche" means, as the context may require, the Term A Loans,
         the Term B Loans, the Term C Loans, the Revolving Loans or the Swing
         Line Loans.

         SECTION 2.2. Amendments to Section 2.1.1. Section 2.1.1 of the Credit
Agreement is hereby amended by inserting a new clause (e) to read as follows:

                  "(e) In a single Borrowing occurring on the First Amendment
         Effective Date, each Lender that has a Term C Loan Commitment will make
         a loan (relative to such Lender, its "Term C Loan") to the Borrower in
         an amount equal to such Lender's Percentage of the aggregate amount of
         the Borrowing of Loans requested by the Borrower to be made on such day
         (with the commitment of each such Lender described in this clause (e)
         herein referred to as its "Term C Loan Commitment").".

         SECTION 2.3. Amendments to Section 2.1.4. Section 2.1.4 of the Credit
Agreement is hereby amended by (i) replacing "; or" at the end of clause (c)
thereof with ";", (ii) replacing "." at the end of clause (d) thereof with ";
or" and (iii) inserting a new clause (e) to read as follows:

                  "(e) any Term C Loan pursuant to any Term C Loan Commitment
         if, after giving effect thereto, the aggregate original principal
         amount of all Term C Loans of such Lender made pursuant to such Term C
         Loan Commitment would exceed such Lender's Percentage of the Term C
         Loan Commitment Amount.".

         SECTION 2.4. Amendments to Section 2.2.2. Section 2.2.2 of the Credit
Agreement is hereby amended by (i) replacing "$15,000,000" with "$30,000,000" in
each of the two instances



                                       4
<PAGE>

in which it occurs therein and (ii) inserting the following proviso at the end
of the first sentence thereof:

         "; provided, further, however, that the parties hereto acknowledge that
         on January 17, 2003, $10,000,000 in additional Revolving Loan
         Commitments were accepted in accordance with this Section, and on March
         6, 2003, $5,000,000 in Additional Term B Loan Commitments were accepted
         in accordance with this Section.".

         SECTION 2.5. Amendments to Section 3.1.1.

         SECTION 2.5.1. Clause (a) of Section 3.1.1 of the Credit Agreement is
hereby amended by amending and restating clause (i) thereof to read in its
entirety as follows:

                  "(i)(x) any such prepayment of Term A Loans, Term B Loans or
         Term C Loans shall be made pro rata among Term A Loans, Term B Loans or
         Term C Loans, as applicable, of the same type and, if applicable,
         having the same Interest Period of all Lenders that have made such Term
         A Loans, Term B Loans or Term C Loans and (y) any such prepayment of
         Revolving Loans shall be made pro rata among the Revolving Loans of the
         same type and, if applicable, having the same Interest Period of all
         Lenders that have made such Revolving Loans;".

         SECTION 2.5.2. Clause (d) of Section 3.1.1 of the Credit Agreement is
hereby amended by replacing "$1,000,000" with "$5,000,000" therein.

         SECTION 2.5.3. Clause (e) of Section 3.1.1 of the Credit Agreement is
hereby amended and restated to read in its entirety as follows:

                  "(e) shall, on the Stated Maturity Date and on each Quarterly
         Payment Date, make a scheduled repayment of the aggregate outstanding
         principal amount, if any, of all Term A Loans, Term B Loans and Term C
         Loans in an amount equal to the applicable percentage of such principal
         amount as provided in the applicable table set forth in Annex I to this
         Agreement (as such principal amounts may have otherwise been reduced
         pursuant to this Agreement);".

         SECTION 2.6. Amendment to Section 3.1.2. Clause (b) of Section 3.1.2 of
the Credit Agreement is hereby amended and restated to read in its entirety as
follows:

                  "(b) Each voluntary prepayment of Term Loans and each
         prepayment of Term Loans made pursuant to clauses (b), (c) and (d) of
         Section 3.1.1 shall be applied (i) first, on a pro rata basis, to the
         outstanding principal amount of all Term Loans and the remaining Term
         Loan amortization payments required pursuant to clause (e) of Section
         3.1.1, until all such Term Loans have been paid in full; provided,
         however, that if the Borrower at any time elects in writing, in its
         sole discretion, to permit any Lender that has Term B Loans or Term C
         Loans to decline to have such Loans prepaid, then any Lender having
         Term B Loans or Term C Loans outstanding may, by delivering a notice to
         the Agents at least one Business Day prior to the date that such
         prepayment is to be made, decline to have such Loans prepaid with the
         amounts set forth above, in which case 100% of the amounts that would
         have been applied to a prepayment of such Lender's Term B Loans or Term
         C Loans, as the case may be, shall instead be applied to



                                       5
<PAGE>

         a prepayment of the Term A Loans (until paid in full); and (ii) second,
         once all Term Loans have been repaid in full, all prepayments of Loans
         made pursuant to clauses (b), (c) and (d) of Section 3.1.1 shall be
         applied to the repayment of any outstanding Revolving Loans without a
         corresponding reduction of the Revolving Loan Commitment Amount.

         SECTION 2.7. Amendment to Section 7.1.7. Clause (a) of Section 7.1.7 of
the Credit Agreement is hereby amended by replacing "$5,000,000" with
"$10,000,000" therein.

         SECTION 2.8. Amendments to Section 7.1.8. Clauses (a) and (b) of
Section 7.1.8 of the Credit Agreement are hereby amended by replacing
"$5,000,000" with "$10,000,000" in each instance in which it occurs therein.

         SECTION 2.9. Amendment to Section 7.2.6. Section 7.2.6 of the Credit
Agreement is hereby amended by inserting the following proviso at the end of
subclause (b)(i) thereof:

         "provided, however, that the Borrower shall be permitted to redeem,
         repurchase, prepay and/or defease up to $4,500,000 of the principal
         amount of the CTS Convertible Subordinated Debt on the First Amendment
         Effective Date with the proceeds of the Borrowing of Term C Loans;".

         SECTION 2.10. Amendment to Section 7.2.7. Section 7.2.7 of the Credit
Agreement is hereby amended and restated to read in its entirety as follows:

                  "SECTION 7.2.7. Capital Expenditures, etc. The Borrower will
         not, and will not permit any of its Subsidiaries to, make or commit to
         make Capital Expenditures in any period set forth below, except Capital
         Expenditures which do not aggregate in excess of the amount set forth
         below opposite such period:


<Table>
<Caption>
                                  Period                            Amount
                                  ------                            ------
<S>                                                              <C>
                  Closing Date through and including             $ 15,000,000
                       December 31, 2000
                  Each Fiscal Year ending December 31,           $ 60,000,000
                       2001 and December 31, 2002
                  Fiscal Year ending                             $ 65,000,000;
                       December 31, 2003 and each
                       Fiscal Year thereafter
</Table>

         provided, however, that to the extent the amount of Capital
         Expenditures permitted to be made in any period pursuant to this
         Section exceeds the aggregate amount of Capital Expenditures actually
         made during such period, up to 100% of such excess amount may be
         carried forward to (but only to) the next succeeding period (any such
         amount to be



                                       6
<PAGE>
         certified by the Borrower to the Agents in the Compliance Certificate
         delivered for the last Fiscal Quarter of such period, and any such
         amount carried forward to a succeeding period shall be deemed to be
         used after the Borrower and its Subsidiaries using the amount of
         Capital Expenditures permitted by this Section without giving effect to
         such carry-forward).".

         SECTION 2.11. Amendment to Annex I. Annex I of the Credit Agreement is
hereby amended to insert the following at the end thereof:

                               THE TERM C FACILITY

<Table>
<Caption>
                                                Scheduled Principal
Quarterly Payment Date                          Repayment Percentage
----------------------                          --------------------
<S>                                             <C>
September 30, 2003                                     0.25%
December 31, 2003                                      0.25%
March 31, 2004                                         0.25%
June 30, 2004                                          0.25%
September 30, 2004                                     0.25%
December 31, 2004                                      0.25%
March 31, 2005                                         0.25%
June 30, 2005                                          0.25%
September 30, 2005                                     0.25%
December 31, 2005                                      0.25%
March 31, 2006                                         0.25%
June 30, 2006                                          0.25%
September 30, 2006                                     0.25%
December 31, 2006                                      0.25%
Stated Maturity Date                                  96.50%
                                                      ------
Total                                                   100%".
</Table>

         SECTION 2.12. Amendment to Schedule II. Part B of Schedule II to the
Credit Agreement is hereby amended and restated in its entirety by substituting
Annex II hereto in lieu thereof.

         SECTION 2.13. Amendment to Exhibits. The Credit Agreement is hereby
amended by (i) inserting a new Exhibit B-3 thereto in the form attached hereto
as Annex III, (ii) amending and restating Exhibit M-1 thereto and replacing it
with a new Exhibit M-1 attached hereto as Annex IV and (iii) amending and
restating Exhibit M-2 thereto and replacing it with a new Exhibit M-2 attached
hereto as Annex V.

                                  ARTICLE III

                              CONDITIONS PRECEDENT

         This Amendment shall become effective, as of the date hereof, upon
satisfaction or waiver of each of the conditions precedent set forth in this
Article III (the first date as of which



                                       7
<PAGE>

each such condition has been satisfied being herein called the "First Amendment
Effective Date").

         SECTION 3.1. Counterparts. The Agents shall have received counterparts
hereof executed on behalf of the Borrower, the Administrative Agent, each Lender
making Term C Loans and each of the Lenders holding at least 51% of the
aggregate outstanding Term A Loans, the Lenders holding at least 51% of the
aggregate outstanding Term B Loans and the Lenders holding at least 51% of the
Revolving Loan Commitments.

         SECTION 3.2. Affirmation and Acknowledgment. The Agents shall have
received, with counterparts for each Lender, a duly executed copy of the
Affirmation and Acknowledgment to this Amendment, substantially in the form of
Annex I hereto and dated the First Amendment Effective Date, duly executed and
delivered by each of the Obligors other than the Borrower (the "Affirmation and
Acknowledgement").

         SECTION 3.3. Resolutions, etc. The Agents shall have received from each
Obligor, a certificate, dated the First Amendment Effective Date, of its
Secretary, Assistant Secretary, general partner or managing member, as
applicable, as to (i) resolutions of its Board of Directors or other governing
body then in full force and effect authorizing the execution, delivery and
performance of this Amendment and each other Loan Document to be executed by it;
(ii) the incumbency and signatures of those of its officers or other persons
authorized to act with respect to this Amendment and each other Loan Document
executed by it; and (iii) its Organic Documents (or a certification that the
Organic Documents delivered on the Amendment Effective Date remain in full force
and effect and have not been modified or terminated since such date), upon which
certificate each Lender may conclusively rely until it shall have received a
further certificate of the Secretary or equivalent Authorized Officer of such
Obligor canceling or amending such prior certificate.

         SECTION 3.4. Credit Extension Request. The Agents shall have received a
Borrowing Request for the Credit Extension with respect to the Term C Loans to
be borrowed on the First Amendment Effective Date. The delivery of a Borrowing
Request and the acceptance by the Borrower of the proceeds of the Borrowing
shall constitute a representation and warranty by the Borrower that on the date
of such Borrowing (both immediately before and after giving effect to such
Borrowing and the application of the proceeds thereof), the statements made in
Section 5.2.1 of the Credit Agreement are true and correct.

         SECTION 3.5. Delivery of Notes. The Administrative Agent shall have
received, for the account of each Lender that has submitted, at least two
Business Days prior to the First Amendment Effective Date, a written request
pursuant to Section 2.7 of the Credit Agreement, its Term C Notes with respect
to the Term C Loans duly executed and delivered by the Borrower.

         SECTION 3.6. First Amendment Effective Date Certificate. The Agents
shall have received, with counterparts for each Lender, a certificate dated as
of the First Amendment Effective Date substantially in the form of Annex VI
hereto (the "First Amendment Effective Date Certificate"), duly executed and
delivered by the chief executive, financial or accounting (or equivalent)
Authorized Officer of the Borrower, as the case may be, in which certificate
such



                                       8
<PAGE>

Person shall agree and acknowledge that the statements made therein shall be
deemed to be true and correct representations and warranties of such Person made
as of such date under this Amendment, and, at the time such certificate is
delivered, such statements shall in fact be true and correct in all material
respects.

         SECTION 3.7. Amended and Restated Security Agreements. The Agents shall
have received executed counterparts of

                  (a) the Amended and Restated Borrower Security Agreement,
         dated as of the First Amendment Effective Date, duly executed by an
         Authorized Officer of the Borrower, substantially in the form of Annex
         IV hereto, together with any revised schedules and financing statements
         (including UCC-1 "in lieu" financing statements) to be delivered in
         connection therewith; and

                  (b) the Amended and Restated Subsidiary Security Agreement,
         dated as of the First Amendment Effective Date, duly executed by each
         of the Subsidiary Guarantors, substantially in the form of Annex V
         hereto, together with any revised schedules and financing statements
         (including UCC-1 "in lieu" financing statements) to be delivered in
         connection therewith.

         SECTION 3.8. Opinion of Counsel. The Agents shall have received an
opinion, dated the First Amendment Effective Date and addressed to the Agents
and all Lenders, from Vinson & Elkins L.L.P., counsel to the Obligors.

         SECTION 3.9. Ratings. The Borrower shall have obtained credit ratings
with respect to its senior secured debt from each of Moody's and S&P (or another
private ratings agency acceptable to CSFB).

         SECTION 3.10. Amendment Fee. The Agents shall have received, for the
account of each Lender signatory hereto on or prior to August 20, 2003 (the "Fee
Calculation Date"), a non-refundable amendment fee equal to 0.10% of each such
Lender's Percentage of the Term A Loans, Term B Loans and Revolving Loan
Commitment as of the Fee Calculation Date.

         SECTION 3.11. Costs and Expenses. The Agents shall have received, for
the account of each Lender signatory hereto on or prior to the Fee Calculation
Date, all other fees, costs and expenses due and payable pursuant to Section
10.3 of the Credit Agreement, if then invoiced. Each Agent shall have received
for its own respective account all fees, costs and expenses due and payable as
of the First Amendment Effective Date (including pursuant to Section 10.3 of the
Credit Agreement and as otherwise agreed).

         SECTION 3.12. Satisfactory Legal Form. All documents executed or
submitted pursuant hereto by or on behalf of the Borrower or any of its
Subsidiaries or any other Obligors shall be reasonably satisfactory in form and
substance to the Agents and their counsel; the Agents and their counsel shall
have received all information, approvals, opinions, documents or instruments as
the Agents or their counsel may reasonably request.



                                       9
<PAGE>

                                   ARTICLE IV

                         REPRESENTATIONS AND WARRANTIES

         SECTION 4.1. Representations and Warranties. In order to induce the
Lenders to consent to the amendments contained herein and the Agents to enter
into this Amendment, the Borrower hereby represents and warrants that the
representations and warranties contained in Article VI of the Credit Agreement
are true and correct, as of the date hereof and as of the First Amendment
Effective Date, in all material respects with the same effect as if then made
(unless stated to relate solely to an earlier date, in which case such
representations and warranties shall be true and correct in all material
respects as of such earlier date) and additionally represents and warrants unto
each Agent and each Lender as set forth in this Article IV.

         SECTION 4.2. Validity, etc. This Amendment constitutes the legal, valid
and binding obligation of the Borrower enforceable in accordance with its terms
(except as such enforceability may be limited by applicable bankruptcy,
insolvency, reorganization or similar laws affecting creditors' rights generally
and by principles of equity).

         SECTION 4.3. No Default. After giving effect to this Amendment and the
Borrowing of the Term C Loans, no Default has occurred and is continuing as of
the First Amendment Effective Date.

         SECTION 4.4. Solvency. The incurrence by the Borrower of the Term C
Loans made on the First Amendment Effective Date, the execution and delivery of
the Affirmation and Acknowledgement by the Obligors other than the Borrower, and
the application of the proceeds of such Credit Extensions will not involve or
result in any fraudulent transfer or fraudulent conveyance under the provisions
of Section 548 of the Bankruptcy Code (11 U.S.C. Section 101 et seq., as from
time to time hereafter amended, and any successor or similar statute) or any
applicable state law respecting fraudulent transfers or fraudulent conveyances.
On the First Amendment Effective Date, after giving effect to the Term C Loans
made on such date and all transactions related thereto, the Borrower and each
Subsidiary Guarantor is Solvent.

                                   ARTICLE V

                            MISCELLANEOUS PROVISIONS

         SECTION 5.1. Ratification of and References to the Credit Agreement.
This Amendment shall be deemed to be an amendment to the Credit Agreement, and
the Amended Credit Agreement is hereby ratified, approved and confirmed in each
and every respect. All references to the Credit Agreement in any other document,
instrument, agreement or writing shall hereafter be deemed to refer to the
Amended Credit Agreement.

         SECTION 5.2. Headings. The various headings of this Amendment are
inserted for convenience only and shall not affect the meaning or interpretation
of this Amendment or any provisions hereof.

         SECTION 5.3. Execution in Counterparts. This Amendment may be executed
by the parties hereto in several counterparts, each of which shall be deemed to
be an original and all of



                                       10
<PAGE>

which shall constitute together but one and the same agreement. A counterpart
hereof executed and delivered by facsimile shall be effective as an original.

         SECTION 5.4. Payment of Costs and Expenses. The Borrower hereby agrees
to pay on demand all expenses of each of the Agents (including the reasonable
fees and out of pocket expenses of counsel to the Agents and of local counsel,
if any, who may be retained by counsel to the Agents) in connection with the
negotiation, preparation, execution and delivery of this Amendment and related
documents, including all fees and disbursements of counsel to such Agent.

         SECTION 5.5. Governing Law; Entire Agreement. THIS AMENDMENT SHALL BE
DEEMED TO BE A CONTRACT MADE UNDER AND GOVERNED BY THE INTERNAL LAWS OF THE
STATE OF NEW YORK. This Amendment and the other Loan Documents constitute the
entire understanding among the parties hereto with respect to the subject matter
hereof and supersede any prior agreements, written or oral, with respect
thereto.



                                       11
<PAGE>
         IN WITNESS WHEREOF, the signatories hereto have caused this Amendment
to be executed by their respective officers thereunto duly authorized as of the
day and year first above written.

                                          W-H ENERGY SERVICES, INC.


                                          By: /s/ Jeffrey L. Tepera
                                             -----------------------------------
                                          Name: Jeffrey L. Tepera
                                          Title: Vice President and Chief
                                                 Financial Officer



                                          CREDIT SUISSE FIRST BOSTON (acting
                                          through its Cayman Islands branch),
                                          as Syndication Agent and as Lender


                                          By: /s/ Thomas L. Newberry
                                             -----------------------------------
                                          Name: Thomas L. Newberry
                                          Title: Managing Director


                                          By: /s/ Denise L. Alvarez
                                             -----------------------------------
                                          Name: Denise L. Alvarez
                                          Title: Associate



                                          BANK ONE, NA (main office Chicago),
                                          as Documentation Agent and as Lender


                                          By: /s/ J. Charles Freel, Jr.
                                             -----------------------------------
                                          Name: J. Charles Freel, Jr.
                                          Title: Director, Capital Markets



                                          WELLS FARGO BANK TEXAS, N.A.,
                                          as Administrative Agent, as Issuer
                                          and as Lender


                                          By: /s/ Eric R. Hollingsworth
                                             -----------------------------------
                                          Name: Eric R. Hollingsworth
                                          Title: Vice President


<PAGE>
                                          SOUTHWEST BANK OF TEXAS, N.A.


                                          By: /s/ Ross Bartley
                                             -----------------------------------
                                          Name: Ross Bartley
                                          Title: Assistant Vice President



                                          LANDMARK CDO LIMITED
                                          By: Aladdin Capital Management LLC
                                              As Manager


                                          By: /s/ Joseph Moroney, CFA
                                             -----------------------------------
                                          Name: Joseph Moroney, CFA
                                          Title: Authorized Signatory



                                          LANDMARK II CDO LIMITED

                                          By: Aladdin Capital Management LLC
                                              As Manager


                                          By: /s/ Joseph Moroney, CFA
                                             ----------------------------------
                                          Name: Joseph Moroney, CFA
                                          Title: Authorized Signatory



                                          Centurion CDO II, Ltd
                                          By: American Express Asset Management
                                              Group, Inc. As Collateral Manager


                                          By: /s/ Leanne Stavrakis
                                             ----------------------------------
                                          Name: Leanne Stavrakis
                                          Title: Director - Operations

<PAGE>


                                           Centurion CDO III, Ltd
                                           By: American Express Asset Management
                                               Group, Inc.
                                               As Collateral Manager


                                           By: /s/ Leanne Stavrakis
                                              ----------------------------------
                                           Name: Leanne Stavrakis
                                           Title: Director - Operations



                                           Centurion CDO VI, Ltd
                                           By: American Express Asset Management
                                               Group, Inc.
                                               As Collateral Manager


                                           By: /s/ Leanne Stavrakis
                                              ----------------------------------
                                           Name: Leanne Stavrakis
                                           Title: Director - Operations



                                           KZH CYPRESSTREE-1 LLC


                                           By: /s/ Dorian Herrera
                                              ----------------------------------
                                           Name: DORIAN HERRERA
                                           Title: AUTHORIZED AGENT



                                           KZH STERLING LLC


                                           By: /s/ Dorian Herrera
                                              ----------------------------------
                                           Name: DORIAN HERRERA
                                           Title: AUTHORIZED AGENT

<PAGE>

                                           Sequils - Centurion V, Ltd.
                                           By: American Express Asset Management
                                               Group, Inc.
                                               As Collateral Manager


                                           By: /s/ Leanne Stavrakis
                                              ----------------------------------
                                           Name: Leanne Stavrakis
                                           Title: Director - Operations



                                           The Foothill Group, Inc.


                                           By: /s/ Dennis R. Ascher
                                              ----------------------------------
                                           Name: Dennis R. Ascher
                                           Title: S.V.P.



                                           Blue Square Funding Series 3
                                           Deutsche Bank Trust Co. Americas
                                           FKA Bankers Trust Co.


                                           By: /s/ Stephen Hessler
                                              ----------------------------------
                                           Name: Stephen Hessler
                                           Title: Vice President



                                           ELF Funding Trust I
                                           By: Highland Capital Management, L.P.
                                               As Capital Manager


                                           By: /s/ Mark Okada
                                              ----------------------------------
                                           Name: Mark Okada
                                           Title: Chief Investment Officer
                                                  Highland Capital Management,
                                                  L.P.

<PAGE>


                                           EMERALD ORCHARD LIMITED


                                           By: /s/ Gwen Zirkle
                                              ----------------------------------
                                           Name: GWEN ZIRKLE
                                           Title: ATTORNEY IN FACT



                                           Highland Legacy Limited (IV)
                                           By: Highland Capital Management, L.P.
                                               As Collateral Manager


                                           By: /s/ Mark Okada
                                              ----------------------------------
                                           Name: Mark Okada
                                           Title: Chief Investment Officer
                                                  Highland Capital Management,
                                                  L.P.



                                           KZH HIGHLAND-2 LLC


                                           By: /s/ Dorian Herrera
                                              ----------------------------------
                                           Name: DORIAN HERRERA
                                           Title: AUTHORIZED AGENT



                                           SRV-HIGHLAND, INC.


                                           By: /s/  Diana M. Himes
                                              ----------------------------------
                                           Name: DIANA M. HIMES
                                           Title: ASSISTANT VICE PRESIDENT


<PAGE>

                                           KZH ING-2 LLC


                                           By: /s/ Dorian Herrera
                                              ----------------------------------
                                           Name: DORIAN HERRERA
                                           Title: AUTHORIZED AGENT



                                           MASTER SENIOR FLOATING RATE TRUST


                                           By: /s/ Omar Jama
                                              ----------------------------------
                                           Name: Omar Jama
                                           Title: Authorized Signatory



                                           MERRILL LYNCH GLOBAL INVESTMENT
                                           SERIES:
                                           INCOME STRATEGIES PORTFOLIO
                                           By: Merrill Lynch Investment
                                               Managers, L.P.
                                               As Investment Advisor


                                           By: /s/ Omar Jama
                                              ----------------------------------
                                           Name: Omar Jama
                                           Title: Authorized Signatory



                                           SENIOR HIGH INCOME PORTFOLIO, INC.


                                           By: /s/ Omar Jama
                                              ----------------------------------
                                           Name: Omar Jama
                                           Title: Authorized Signatory


<PAGE>

                                           NATEXIS BANQUES POLULAIRES


                                           By: /s/ Timothy Polvado
                                              ----------------------------------
                                           Name: Timothy Polvado
                                           Title: Vice President / Manager


                                           By: /s/ Donovan C. Broussard
                                              ----------------------------------
                                           Name: Donovan C. Broussard
                                           Title: Vice President / Manager



                                           ING Prime Rate Trust
                                           By: Aeltus Investment Management,
                                               Inc.
                                               as its investment manager


                                           By: /s/ Charles E. LeMieux
                                              ----------------------------------
                                           Name: CHARLES E. LeMIEUX, CFA
                                           Title: VICE PRESIDENT



                                           ING Senior Income Fund
                                           By: Aeltus Investment Management,
                                               Inc.
                                               as its investment manager


                                           By: /s/ Charles E. LeMieux
                                              ----------------------------------
                                           Name: CHARLES E. LeMIEUX, CFA
                                           Title: VICE PRESIDENT



                                           ML CLO XX PILGRIM AMERICA
                                           (CAYMAN) LTD.
                                           By: ING Investments, LLC
                                               As its investment manager


                                           By: /s/ Charles E. LeMieux
                                              ----------------------------------
                                           Name: CHARLES E. LeMIEUX, CFA
                                           Title: VICE PRESIDENT