DRAFT:  11/11/97

                    AMENDMENT ONE TO STOCK PURCHASE AGREEMENT


     This  Amendment One to Stock  Purchase  Agreement,  dated as of October 10,
1997, amends the Stock Purchase Agreement (the "Stock Purchase Agreement") dated
as of July 31, 1997 among Nabors Acquisition Corp. IV (the "Seller"),  Key Rocky
Mountain,  Inc.  (the "Buyer") and Key Energy Group,  Inc.  ("Key  Energy") with
respect to Seller's sale of all the issued and outstanding capital stock of J.W.
Gibson Well Service  Company  (the  "Company").  Capitalized  terms used but not
defined herein are used as defined in the Stock Purchase Agreement.


     WHEREAS, the parties desire to amend the Stock Purchase Agreement to change
the Closing Date, to make certain other changes  related  thereto and to clarify
certain other conditions and provisions thereof; and


     WHEREAS, the parties are concurrently  amending the Operating Agreement and
Escrow  Agreement  to give effect to the  changes  made hereby and to enter into
certain other agreements;


     NOW,  THEREFORE,  in consideration of the above recitals and other good and
valuable  consideration,  the  receipt  and  sufficiency  of  which  are  hereby
acknowledged,  the  Seller,  the  Buyer  and Key  Energy  agree to make  certain
amendments to the Stock Purchase Agreement as follows:

     1. From and after effectiveness of this Amendment and the amendments to the
Operating Agreement and the Escrow Agreement, the terms "Agreement",  "Operating
Agreement" and "Escrow  Agreement" used in the Stock Purchase Agreement shall be
deemed to refer to each such  agreement  as amended on the date hereof or as may
be amended from time to time.  2.  Section 2.3 is hereby  amended to read in its
entirety as follows:

     2.3 Additional Purchase Price Adjustments and Procedures.ts and Procedures


     (a) On the date  hereof,  the Buyer has  delivered  to the Seller a balance
sheet of the Company as of July 31, 1997 (the "July 31 Balance Sheet"). The July
31 Balance  Sheet shall have included all  information  necessary to compute the
Working Capital of the Company. The Buyer shall make available to the Seller all
information which may be in the possession of the Buyer or the Company which the
Seller  requests in order to verify the  accuracy of the July 31 Balance  Sheet.
Within 60 days from the date hereof,  the Seller shall notify the Buyer  whether
it agrees with the July 31 Balance Sheet. In the event that the Seller disagrees
with the July 31  Balance  Sheet,  the  Seller  shall  provide  the Buyer with a
written  notice  specifying  the basis for the  Seller's  disagreement,  and the
Seller  and the  Buyer  shall  work in good  faith  to  reach  agreement  on the
composition of the July 31 Balance Sheet,  but, in the event that they shall not
agree within 30 days following the date of such written notice,  the matter will
be referred to a "Big Six" independent public accounting firm mutually agreed to
by the Buyer and the Seller.  The fees and disbursements of such accounting firm
shall be borne equally by the Buyer and the Seller.  Such  accounting firm shall
examine the records of the Company,  and, within 30 days following the date upon
which such matter shall be referred to such  accounting  firm,  such  accounting
firm shall  determine the disposition of any dispute with respect to the July 31
Balance  Sheet  (the date on which the  determination  is made,  whether  by the
accounting  firm or by agreement  of the  parties,  is referred to as the "Final
Determination  Date"). Any such determination  shall be final and binding on the
parties, and may be enforced by appropriate judicial or other proceedings.


     (b) (i) In the event that the  Working  Capital of the Company is less than
the Estimated Working Capital,  then the amount of such difference shall be paid
by the Seller to the Buyer within two business  days of the Final  Determination
Date,  plus  interest  of 8% per annum  payable  from July 31, 1997 to the Final
Determination  Date.  If the Final  Determination  Date  occurs  at least  three
business  days prior to the Closing  Date,  and the Seller is required to make a
payment  to the Buyer in  accordance  with the first  sentence  of this  Section
2.3(b)(i),  the  additional  amount due shall be disbursed to the Buyer from the
funds deposited with the escrow agent under the Escrow Agreement.


     (ii) In the event that the Working  Capital of the Company is more than the
Estimated  Working Capital,  then the amount of such difference shall be paid by
the Buyer to the Seller  within  two  business  days of the Final  Determination
Date,  plus  interest  of 8% per annum  payable  from July 31, 1997 to the Final
Determination  Date.  If the Final  Determination  Date  occurs  at least  three
business  days prior to the  Closing  Date,  and the Buyer is required to make a
payment to the Seller in  accordance  with the third  sentence  of this  Section
2.3(b),  the Buyer shall deposit the additional amount due with the escrow agent
under the Escrow Agreement.


     (iii) Each of the Seller,  the Buyer and Key Energy  agrees to provide such
notices as may be required under the Escrow  Agreement to carry out the purposes
and intents of this Section 2.3(b).


     (c) The July 31 Balance Sheet shall have been  prepared in accordance  with
generally accepted accounting principles applied in a manner consistent with the
Company's  historical  accounting  policies  and  practices;   except  that  all
intercompany  balances will be  eliminated.  Each party agrees to use reasonable
efforts to arrive at a final  determination  of the Purchase Price adjustment on
or before the Closing Date.


     (d) On or prior to 90 days from the Closing  Date,  the Seller will prepare
and deliver to the Buyer a  calculation  of the State Tax  Detriment (as defined
below) resulting from the sale of the Company, showing all necessary information
for  such  calculation.  The  Seller  shall  make  available  to the  Buyer  all
information  which  may be in the  possession  of the  Seller  which  the  Buyer
reasonable  requests in order to verify the accuracy of the State Tax  Detriment
calculation.  Within 30 days following  delivery of the calculation of the State
Tax Detriment,  the Buyer shall notify the Seller whether it disagrees with such
calculation  and the Buyer shall be deemed to agree with such  calculation if no
notice of disagreement  is received  within such time period.  In the event that
the Buyer disagrees with such calculation,  the Buyer shall attach to its notice
of disagreement or incorporate therein a written notice specifying the basis for
the Buyer's disagreement,  and the Seller and the Buyer shall work in good faith
to reach  agreement  on the  calculation  but,  in the event that they shall not
agree within 30 days following the date of such written notice,  the matter will
be  referred to a  nationally  recognized  independent  public  accounting  firm
mutually agreed to by the Buyer and the Seller.  The fees and the  disbursements
of such accounting firm shall be borne equally by the Buyer and the Seller. Such
accounting  firm shall  examine the records of the Seller and the Company,  and,
within 30 days  following  the date upon which such matter  shall be referred to
such  accounting  firm,  such accounting firm shall determine the disposition of
any dispute with respect to the  calculation.  Any such  determination  shall be
final and binding on the parties, and may be enforced by appropriate judicial or
other  proceedings.  Payment of the amount of the State Tax  Detriment  shall be
made by the Buyer to the Seller no later than five  business days after the date
agreement  is reached  between  the Buyer and the Seller or the  decision of the
accounting firm is made. The "State Tax Detriment" equals the difference between
(A) the state Taxes  payable by the Seller or any  related  party as a result of
making the Section 338(h)(10)  election  contemplated by Section 5.11(c) of this
Agreement  and (B) the state  Taxes that would have been  payable as a result of
the sale pursuant to this Agreement had such a Section  338(h)(10)  election not
been made, such  calculation to be grossed up for any additional  state or other
Taxes payable as a result of the payment to the Seller under this provision."

     3.  Section  2.4,  clause  (a) of the Stock  Purchase  Agreement  is hereby
amended to read in its entirety as follows:  "(a) a date between January 2, 1998
and  January 15, 1998 or".  4.  Sections  7.1 (b) and (c) are hereby  amended by
changing the date therein from "December 31, 1997" to "January 31, 1998". 5. The
Loan  Agreement  referenced  in  Schedule  3.6 to the  Disclosure  Schedule  was
terminated on September 10, 1997,  and UCC-3  termination  statements  have been
filed with respect thereto,  all as evidenced on Attachment 1 hereto. The Seller
represents  and  warrants  to  the  Buyer  and  Key  Energy  that  there  are no
encumbrances arising under such Loan Agreement on the Company or its property at
the date hereof and agrees that it will perform all acts reasonably requested by
the  Buyer  to  remove  any  such   encumbrances  in  the  event  the  foregoing
representation  is not  true.  The  execution  and  delivery  of this  Amendment
satisfies  the  closing  condition  set  forth in  Section  6.1(i)  of the Stock
Purchase Agreement. 6. The parties hereby agree that, notwithstanding footnote 2
to Schedule 3.14 of the Disclosure  Schedule,  as promptly as practicable  after
the date hereof an  affiliate  of the Seller will convey to the Company the yard
in Gillette,  Wyoming  referenced  in such Schedule  3.14,  and the Company will
convey  to an  affiliate  of the  Seller  the  yard  in  Rock  Springs,  Wyoming
referenced in such Schedule 3.14. Such conveyances will be in substantially  the
forms attached hereto as Attachment 2.



     IN WITNESS WHEREOF,  the undersigned have executed this Amendment as of the
date first written above.


                                                   NABORS ACQUISITION CORP. IV

                      By:                                                  
                                                         Larry P. Heidt
                                                       Executive Vice President


                                                      KEY ROCKY MOUNTAIN, INC.


                                  By:                                         
Stephen E. McGregor
Executive Vice President

                                                        KEY ENERGY GROUP, INC.


                                  By:                                         
Stephen E. McGregor
Vice President

































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