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                                                                   EXHIBIT 10.20

                    SECOND AMENDMENT TO DEPOSITORY AGREEMENT
                               FOR PURCHASE OPTION


     THIS SECOND AMENDMENT TO DEPOSITORY AGREEMENT FOR PURCHASE OPTION (this
"Second Amendment") is entered into as of February __, 2001 by and between Grant
Geophysical Corp., a Texas corporation ("Grant"), and Elliott Associates, L.P.,
a Delaware limited partnership ("Elliott").

                                   WITNESSETH:

     WHEREAS, Grant and Elliott are the parties to that certain Depository
Agreement for Purchase Option dated as of December 1, 2000 (the "Original
Agreement"), as amended by that certain Amendment to Depository Agreement for
Purchase Agreement dated January 25, 2001 (the "First Amendment", the Original
Agreement as amended by the First Amendment is the "Depository Agreement"); and

     WHEREAS, Grant and Elliott deem it in their best interests to amend the
Depository Agreement to redefine and extend the expiration date of the Option
and concurrently to provide for a reduction in the amount of the exercise price
of the Option and the Deposit in the event there is a sale to a third party of a
portion of the property that is the subject of the Option.

     NOW, THEREFORE, the parties agree as follows:

     1. Section 1(a) of the Depository Agreement is amended to read in its
     entirety as follows:

        "(a) Purchase Option. Grant hereby grants to Elliott the exclusive
             option (the "Option") to purchase on or before December 31, 2001
             all of Grant's right, title and interest in and to the La Fite Data
             Survey (the "Survey")."


     2. Section 1(b) of the Depository Agreement is amended to read in its
     entirety as follows:

        "(b) Purchase Price. The exercise price of the Option shall be the sum
             of $1,850,000, reduced in the same manner as the refund of the
             Amended Deposit described in Section 1(c)(iii)(B), payable in the
             manner set forth in Section 1(c)."

     3. Section 1(c) of the Depository Agreement is amended in its entirety to
     read as follows:


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        "(c) Refundable Deposit.

             (i)   On December 1, 2000, Elliott placed on deposit with Grant a
                   $1,000,000 refundable deposit (the "Original Deposit").

             (ii)  On January 25, 2001, Elliott increased the amount of the
                   Original Deposit to $1,850,000 (the "Amended Deposit").

             (iii) Between January 25, 2001 and December 31, 2001, but before
                   Elliott exercises the Option or gives Grant notice that it
                   elects not to exercise the Option:

                      (A) if Grant elects to sell the entire Survey to a third
                          party, Grant shall give Elliott written notice of such
                          election and refund the Amended Deposit in full,
                          together with a termination fee of $18,333, plus
                          $616.66 for each day beginning on January 25, 2001 and
                          ending on the day the refund and termination fee are
                          paid, and in such event the Option shall be cancelled;
                          or

                      (B) if Grant elects to sell licenses to the Survey to
                          third parties and retain ownership of the Survey (the
                          "License Sales"), for so long as the Option remains in
                          effect Grant shall give Elliott written notice of each
                          License Sale and deliver to Elliott, in cash, 100% of
                          the proceeds of each License Sale (the "Cash
                          Payment"). Each Cash Payment shall be applied (x)
                          first to satisfy a termination fee that consists of
                          the sum of $18,333 plus 12% per annum on the then
                          current amount of the Amended Deposit from January 25,
                          2001, through the date of the current Cash Payment,
                          minus any prior termination fee payments, and (y) then
                          to a partial refund of the Amended Deposit until the
                          Amended Deposit has been refunded in full, at which
                          time the Option shall be cancelled.

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             (iv)  Elliott may exercise the Option without payment of further
                   consideration by giving Grant written notice of exercise that
                   includes the date on or before December 31, 2001 upon which
                   the purchase of the Survey shall close. On the closing date
                   (A) Grant shall deliver to Elliott an assignment, bill of
                   sale and conveyance in a form acceptable to Elliott and such
                   other documents as may be necessary to convey title to the
                   Survey, and (B) upon such delivery the then current amount of
                   the Amended Deposit shall become Grant's property.


             (v)   If (A) Elliott gives Grant written notice that it elects not
                   to exercise the Option, or (B) the Option remains in force
                   and is not exercised on December 31, 2001, Grant shall refund
                   the then current amount of the Amended Deposit to Elliott no
                   later than two business days after the earlier of receipt of
                   such written notice from Elliott or December 31, 2001."

     4. Section 1(d) of the Depository Agreement is amended in its entirety to
     read as follows:

        "(d) Title Warranty. Grant represents and warrants to Elliott that the
             Survey, when conveyed upon exercise of the Option by Elliott, shall
             be free and clear of any mortgages, deeds of trust, voluntary or
             contractual or statutory liens, pledges, security interests,
             charges, conditional sales or other title retention documents.
             Grant hereby covenants to bind itself, its successors and assigns
             to warrant and forever defend the title to the Survey granted,
             conveyed, assigned, and transferred unto Elliott, its successors
             and assigns, against the lawful claims and demands of every Person
             whomsoever claiming or to claim the same or any part thereof, by,
             through or under Grant."

     5. Except as specifically amended by this Amendment, all of the terms and
provisions of the Depository Agreement shall remain in full force and effect.

     6. All capitalized terms used herein but not defined herein shall have the
meanings given to them in the Depository Agreement.

     7. This Amendment shall be governed by and construed in accordance with the
internal laws of the State of New York.

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

WITNESSES:                             GRANT GEOPHYSICAL CORP.

                                       By:
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                                           Thomas Easley
                                           President
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WITNESSES:                             ELLIOTT ASSOCIATES, L.P.

                                       By:
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                                           Paul E. Singer
                                           General Partner
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