<PAGE>

  Each such payment of net proceeds from the sale of Restricted Shares shall be
deemed to be a prepayment of a like amount of principal under the Notes and
shall be allocated pro rata between the two outstanding Notes. Quarterly
interest payments on the Notes shall be adjusted to reflect such prepayments of
principal and the timing thereof.

  All sales of Restricted Shares by the Company, as described above, must be 
made in arms-length transactions, and under no circumstances may the Company or 
any officer, director or principal stockholder of the Company acquire, directly 
or indirectly, any payment, right to purchase or any other right related to any
Restricted Shares in connection with any such sale thereof.  Any sale of 
Restricted Shares by the Company which is not made in compliance with all of the
terms described in this letter (including the payment of proceeds from such 
sales directly to Norex), shall be deemed to be an "Event of Default" under the 
Second Amended and Restated Master Restructuring Agreement dated as of April 
16, 1993, as amended between the Company and Norex Drilling Ltd (the "MRA").

  Notwithstanding anything to the contrary herein, the requirements of the 
second and fourth paragraphs of this letter prohibiting participation in any 
purchases of Restricted Shares by the Company or any officer, director or 
principal stockholder thereof shall be deemed satisfied if neither the Company 
nor any such officer, director or principal stockholder (other than Norex and 
its affiliates, including Kristian Siem) has knowledge of any such
participation, and the requirement of the second paragraph of this letter that
sales be made at fair market value shall be deemed satisfied if such sales are
made in customary market transactions to or through a broker or dealer.

  The number of shares of TDW Stock which may be acquired by Norex pursuant to 
Section 4.A of the Notes shall be reduced from time to time by the corresponding
number of Restricted Shares which are sold by the Company in compliance with the
terms described in this letter. Following the sale by the Company of all of the 
Restricted Shares in compliance with the terms described in this letter, Section
4 of the Notes shall be deemed to be deleted.

Cash Tender Offer

  Norex, as holder of all the outstanding Notes, hereby waives any breach by 
the Company of the covenant set forth in Section 8.1(c) of the MRA resulting 
from a single cash tender offer made by the Company to all of its stockholders 
for the purchase of up to 15,000,000 shares of Common Stock at a purchase price 
of not less than $4.00 per share, which offer shall be completed prior to
April 30, 1995. If, as a result of the completion of such cash tender offer, the
Company's Consolidated Tangible Net Worth (as defined in the MRA) falls below
$100,000,000, Section 8.1(c) of the MRA shall thereupon be deemed to be amended
to read in its entirety as follows:

       (c) Consolidated Tangible Net Worth. At any time permit Consolidated 
    Tangible Net Worth to be less than $75,000,000.

                                       2