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                                                                 EXHIBIT 99.4

                             SHAREHOLDER AGREEMENT




May 14, 1997

National-Oilwell, Inc.
5555 San Felipe
P.O. Box 4638
Houston, Texas 77210


Attention:  President

Reference is made to the Combination Agreement by and between National-Oilwell,
Inc. ("NOI") and Dreco Energy Services Ltd. ("Dreco") dated as of May 14, 1997
(the "Agreement"), the other transactions contemplated by the Agreement (the
"Contemplated Transactions") and the arrangement (the "Arrangement") under Part
15 of the Business Corporations Act (Alberta) substantially in the form of
Exhibit A to the Agreement, all providing for the combination of NOI and Dreco.
As an inducement to, and in consideration of, NOI's entering into the
Agreement, the undersigned covenants and agrees as follows:

       (i)    At any meeting of the shareholders of Dreco at which either the
              approval of the  Arrangement or of the Contemplated Transactions
              or both are to be voted upon, the undersigned will vote any
              voting securities (the "Securities") of Dreco over which the
              undersigned has voting authority in favor of the approval of the
              Arrangement and of the Contemplated Transactions unless the Board
              of Directors of Dreco is recommending, at the time of such
              meeting, that shareholders of Dreco vote against such approval in
              view of the pendency of a Superior Proposal (as defined in the
              Agreement).

       (ii)   Until the Closing (as defined in the Agreement) or the
              termination of the Agreement, the undersigned will not directly
              or indirectly (a) solicit, initiate or encourage (including by
              way of furnishing information) or take any other action to
              facilitate any inquiries or the making of any proposal which
              constitutes or may reasonably be expected to lead to an
              Acquisition Proposal (as defined in the Agreement) from any
              person or (b) engage in any discussion or negotiations relating
              thereto or accept any Acquisition Proposal; provided that the
              foregoing clause (b) shall not prohibit the undersigned, a
              director of Dreco, from acting (subject to the Agreement) solely
              in his capacity as a director of Dreco.





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       (iii)  Until the Closing (as defined in the Agreement) or the
              termination of the Agreement, the undersigned will not sell,
              contract to sell or otherwise dispose of any voting securities of
              Dreco over which the undersigned has dispositive authority.

Very Truly Yours,


/s/ FREDERICK W. PHEASEY                                      
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Frederick W. Pheasey