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                                                                    EXHIBIT 10.4

                                                                  EXECUTION COPY


                                 FIRST AMENDMENT
                                       TO
                              EMPLOYMENT AGREEMENT


                  THIS FIRST AMENDMENT TO EMPLOYMENT AGREEMENT is executed
between Kenneth V. Huseman (the "Executive") and Sierra Well Service, Inc. (the
"Company") effective as of March 21, 2000.

                  WHEREAS, the Executive and the Company have entered into an
Employment Agreement dated as of March 16, 1999 (the "Employment Agreement");
and

                  WHEREAS, the Employment Agreement provides for the issuance to
the Executive of Bonus Shares on each of the first five anniversaries of the
Commencement Date, subject to the further provisions of the Employment
Agreement;

                  WHEREAS, the Company and the Executive desire to amend the
Employment Agreement to provide, in lieu of the future issuance of shares of
Bonus Stock, for the immediate issuance of restricted shares of Bonus Stock to
the Executive; and

                  WHEREAS, Executive and the Company with to clarify certain
additional terms of the Employment Agreement;

                  NOW, THEREFORE, the parties hereby amend the Employment
Agreement to provide as follows:

                  1. In lieu of the issuance of shares of Bonus Stock to the
                  Executive on each of the first five anniversaries of the
                  Commencement Date, as provided in Section 3(b) of the
                  Employment Agreement, the Company hereby grants to the
                  Executive 91.06 shares of Restricted Bonus Stock. Such shares
                  are nontransferable (other than by will and the laws of
                  descent and distribution) and are subject to vesting and
                  forfeiture on the same basis as provided in the Employment
                  Agreement with respect to the Bonus Stock, as in effect prior
                  to this First Amendment. For example, shares of Restricted
                  Bonus Stock shall become unrestricted, vested shares of Bonus
                  Stock on the dates that were provided for the issuance of
                  Bonus Stock under the provisions of the Employment Agreement
                  as in effect prior to this First Amendment and shall be
                  forfeited on the dates that the Executive's right to receive
                  additional shares of Bonus Stock would terminate under the
                  provisions of the Employment Agreement as in effect prior to
                  this First Amendment.



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                  2. Based upon shares of Common Stock reasonably anticipated to
                  be issued to Enron or its designees in accordance with the
                  conversion of Series B Convertible Preferred Stock, the
                  Company hereby grants to the Executive 39.02 shares of Bonus
                  Stock (the "JEDI Bonus Stock"), which shares shall be vested
                  as if issued pursuant to Section 3(a) of the Employment
                  Agreement but shall remain non-transferable by the Executive
                  and subject to forfeiture pursuant to Section 3(e) of the
                  Employment Agreement if shares of Common Stock are not in fact
                  issued in the future to Enron or its designees.

                  3. In addition, based upon shares of Common Stock reasonably
                  anticipated to be issued to Enron or its designees in
                  accordance with the conversion of Series B Convertible
                  Preferred Stock, the Company hereby grants to the Executive an
                  additional 39.02 shares of Common Stock (the "Restricted JEDI
                  Bonus Stock"), which shares shall be subject to vesting in the
                  same manner as shares of Restricted Bonus Stock as set forth
                  in Section 1 of this First Amendment and shall remain non-
                  transferable by the Executive and subject to forfeiture
                  pursuant to Section 3(e) of the Employment Agreement if shares
                  of Common Stock are not in fact issued in the future to Enron
                  or its designees.

                  4. Additional shares of Restricted Bonus Stock or vested Bonus
                  Stock shall be issued to, or forfeited by, the Executive on
                  the same basis as provided in Section 3(d) and (e) with
                  respect to the Bonus Stock as in effect prior to this First
                  Amendment.

                  5. All distributions made with respect to shares of Restricted
                  Bonus Stock (cash, stock or other property), and any shares
                  issued upon a stock split or stock dividend, shall be subject
                  to the same restrictions, and the same vesting and forfeiture
                  provisions, as are applicable to the shares of Restricted
                  Bonus Stock hereby granted to the Executive.

                  6. All distributions made with respect to shares of JEDI Bonus
                  Stock (cash, stock or other property), and any shares issued
                  upon a stock split or stock dividend, shall be subject to the
                  same restrictions, and the same forfeiture provisions, as are
                  applicable to the shares of JEDI Bonus Stock hereby granted to
                  the Executive.

                  7. All distributions made with respect to shares of JEDI
                  Restricted Bonus Stock (cash, stock or other property), and
                  any shares issued upon a stock split or stock dividend, shall
                  be subject to the same restrictions, and the same forfeiture
                  provisions, as are applicable to the shares of JEDI Restricted
                  Bonus Stock hereby granted to the Executive.

                  8. The Company may place such legends on the certificate(s)
                  for the shares of Restricted Bonus Stock, JEDI Bonus Stock and
                  JEDI Restricted Bonus Stock as the Company may determine to be
                  appropriate to evidence the above restrictions.



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                  9. The Company and the Executive hereby agree that 91.06
                  shares of Bonus Stock issued pursuant to the Employment
                  Agreement prior to the date hereof was, and is, the proper and
                  correct issuance of Bonus Stock pursuant to Section 3 of the
                  Employment Agreement. The Company and the Executive further
                  agree that if Enron and its designees are issued shares of
                  Common Stock upon conversion of the Company's Series B
                  Convertible Preferred Stock in accordance with Section
                  8.a.(ii) of the Certificate of Designations for the Company's
                  Series B Convertible Preferred Stock (i.e., into an aggregate
                  of 30% of the total number of fully diluted shares of Common
                  Stock, assuming no additional shares of Common Stock are
                  issued after the date hereof that will be included the formula
                  presented in this Certificate of Designations), these 91.06
                  shares of Bonus Stock, together with the shares of JEDI Bonus
                  Stock, the Restricted Bonus Stock and the Restricted JEDI
                  Bonus Stock shall represent all of the shares to which the
                  Executive is entitled pursuant to the Employment Agreement (in
                  each case subject to anti-dilution protection for stock
                  dividends, stock splits and other capital reorganization
                  events). Notwithstanding the foregoing, the Executive shall be
                  entitled to an adjustment to shares of Bonus Stock issuable
                  pursuant to Section 3 of the Employment Agreement in the event
                  the Company issues shares of Common Stock to Enron or its
                  affiliates other than upon conversion of the Series B
                  Convertible Preferred Stock in accordance with Section
                  8.a.(ii) of the Certificate of Designations related thereto.

                  All terms used herein that are defined in the Employment
Agreement shall have the same meanings given to such terms in the Employment
Agreement, except as otherwise expressly provided herein.

                  Except as amended and modified hereby, the Employment
Agreement shall continue in full force and effect and the Employment Agreement
and this First Amendment shall be read, taken and construed as one and the same
instrument.

                  This instrument may be executed in several counterparts, each
of which shall be deemed an original, but all of which shall constitute but one
and the same instrument which may be evidenced by any one counterpart.



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                  IN WITNESS WHEREOF, the parties have executed this First
Amendment to the Employment Agreement effective for all purposes as of the date
first above written.

                                       SIERRA WELL SERVICE, INC.

                                       By: /s/ H.H. WOMMACK III
                                          --------------------------------------
                                       Name:   H.H. Wommack III
                                            ------------------------------------
                                       Title:  Chairman
                                             -----------------------------------


                                       Executive

                                       /s/ KENNETH V. HUSEMAN
                                       -----------------------------------------
                                       Kenneth V. Huseman



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