Document:

<PAGE>
                                                                   EXHIBIT 10.54

                 STANDSTILL, FORBEARANCE AND AMENDMENT AGREEMENT

     This STANDSTILL, FORBEARANCE AND AMENDMENT AGREEMENT (this "Standstill
Agreement"), dated as of June 21, 2002, is among SEITEL, INC. (the "Company"), a
Delaware corporation, and each of the investors listed on the signature pages
hereto (together with successors and assigns of each, a "Noteholder," and
collectively, the "Noteholders"). Capitalized terms have the respective meanings
ascribed thereto in Section 1 hereof.

                              W I T N E S S E T H:

     WHEREAS, each of the 1995 Noteholders and the Company are party to those
certain separate Note Purchase Agreements dated as of December 28, 1995
(collectively, as amended, the "1995 Note Purchase Agreement"), providing for
the sale by the Company and the purchase by the 1995 Noteholders of the
Company's 7.17% Series B Senior Notes due December 30, 2002 (the "Series B
Notes") in the aggregate original principal amount of $27,500,000 and the
Company's 7.48% Series C Senior Notes due December 30, 2002 (the "Series C
Notes") in the aggregate original principal amount of $22,500,000; and

     WHEREAS, each of the 1999 Noteholders and the Company are party to those
certain separate Note Purchase Agreements dated as of February 12, 1999
(collectively, as amended, the "1999 Note Purchase Agreement"), providing for
the sale by the Company and the purchase by the 1999 Noteholders of the
Company's 7.03% Series D Senior Notes due February 15, 2004 (the "Series D
Notes") in the aggregate original principal amount of $20,000,000, the Company's
7.28% Series E Senior Notes due February 15, 2009 (the "Series E Notes") in the
aggregate original principal amount of $75,000,000 and the Company's 7.43%
Series F Senior Notes due February 15, 2009 (the "Series F Notes") in the
aggregate original principal amount of $43,000,000; and

     WHEREAS, each of the 2001 Noteholders and the Company are party to those
certain separate Note Purchase Agreements dated as of October 15, 2001
(collectively, the "2001 Note Purchase Agreement"), providing for the sale by
the Company and the purchase by the 2001 Noteholders of the Company's 7.04%
Series G Senior Notes due October 15, 2006 (the "Series G Notes") in the
aggregate original principal amount of $20,000,000, the Company's 7.19% Series H
Senior Notes due October 15, 2008 (the "Series H Notes") in the aggregate
original principal amount of $50,000,000 and the Company's 7.34% Series I Senior
Notes due October 15, 2011 (the "Series I Notes") in the aggregate original
principal amount of $37,000,000; and

<PAGE>

     WHEREAS, the 1995 Note Purchase Agreement, the 1999 Note Purchase Agreement
and the 2001 Note Purchase Agreement are collectively referred to herein as the
"Note Purchase Agreements;" and

     WHEREAS, the Series B Notes, the Series C Notes, the Series D Notes, the
Series E Notes, the Series F Notes, the Series G Notes, the Series H Notes and
the Series I Notes are collectively referred to herein as the "Notes;" and

     WHEREAS, the obligations of the Company under the Note Purchase Agreements
and the Notes have been guaranteed by the Restricted Subsidiaries pursuant to
the Subsidiary Guaranties; and

     WHEREAS, on the date hereof, the Company's records indicate that each
Noteholder is the registered owner, in its own or its nominee's name, of one or
more of the Notes; and

     WHEREAS, certain Defaults or Events of Default have occurred and are
continuing; and

     WHEREAS, the Company acknowledges and agrees that the Noteholders currently
have the right under the Note Purchase Agreements to accelerate the Notes
immediately and otherwise exercise, or cause to be exercised, all rights and
remedies available to the Noteholders under the Note Purchase Agreements and
under law and in equity; and

     WHEREAS, the Company has requested that the Noteholders forbear from
exercising any rights and remedies in respect of any Existing Event of Default
during the Standstill Period and that the Noteholders provide certain other
accommodations to the Company as set forth herein; and

     WHEREAS, the Company has, in consideration of the accommodations referred
to in the immediately foregoing clause, agreed to comply with the terms and
conditions of this Standstill Agreement; and

     WHEREAS, the Company and each Noteholder are desirous of entering into this
Standstill Agreement on the terms and conditions hereinafter set forth.

     NOW, THEREFORE, in consideration of the matters referred to above, the
mutual covenants set forth herein, and other good and valuable consideration,
the receipt and sufficiency of which are hereby acknowledged, the parties hereto
agree as follows:

                                       2

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1.   DEFINITIONS.

     The following terms listed below have the meanings set forth below.
Capitalized terms used and not otherwise defined herein shall have the meanings
assigned to them in the Note Purchase Agreements.

     "Company" has the meaning assigned to such term in the first paragraph
hereof.

     "Effective Date" has the meaning assigned to such term in Section 8.

     "Existing Event of Default" means an Event of Default listed on Exhibit A
hereto.

     "Financial Advisor" has the meaning assigned to such term in Section 5(c).

     "Financial Advisor Engagement Agreement" has the meaning assigned to such
term in Section 5(c).

     "Financing Documents" means, collectively, each of the separate Note
Purchase Agreements, as amended, the Notes, as amended, the Subsidiary
Guaranties, and each of the other documents executed in connection with any of
the foregoing, as any such documents may be amended from time to time.

     "Heller Debt" means the Debt of Seitel Data, Ltd. in favor of Heller
Financial Services, Inc. to the extent that the aggregate principal amount of
such Debt does not exceed $10,000,000.

     "1995 Note Purchase Agreement" has the meaning assigned to such term in the
first "whereas" clause of this Standstill Agreement.

     "1995 Noteholders" means the parties listed in Schedule A hereto.

     "1999 Note Purchase Agreement" has the meaning assigned to such term in the
second "whereas" clause of this Standstill Agreement.

     "1999 Noteholders" means the parties listed in Schedule B hereto.

     "Noteholders" has the meaning assigned to such term in the first paragraph
hereof.

     "Note Purchase Agreements" has the meaning assigned to such term in the
fourth "whereas" clause of this Standstill Agreement.

     "Notes" has the meaning assigned to such term in the fifth "whereas" clause
of this Standstill Agreement.

                                        3

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     "Person" means and includes an individual, partnership, limited liability
company, joint venture, corporation, trust, unincorporated organization or any
government or any department or agency thereof.

     "Required Noteholders" shall mean the holders of a majority of the
principal amount of the Notes then outstanding issued under each of the 1995
Note Purchase Agreement, the 1999 Note Purchase Agreement and the 2001 Note
Purchase Agreement.

     "Series B Notes" has the meaning assigned to such term in the first
"whereas" clause hereof.

     "Series C Notes" has the meaning assigned to such term in the first
"whereas" clause of this Standstill Agreement.

     "Series D Notes" has the meaning assigned to such term in the second
"whereas" clause of this Standstill Agreement.

     "Series E Notes" has the meaning assigned to such term in the second
"whereas" clause of this Standstill Agreement.

     "Series F Notes" has the meaning assigned to such term in the second
"whereas" clause of this Standstill Agreement.

     "Series G Notes" has the meaning assigned to such term in the third
"whereas" clause of this Standstill Agreement.

     "Series H Notes" has the meaning assigned to such term in the third
"whereas" clause of this Standstill Agreement.

     "Series I Notes" has the meaning assigned to such term in the third
"whereas" clause of this Standstill Agreement.

     "Senior Officer" means with respect to any Person, any member of the board
of directors, the chief executive officer, the chief operating officer, the
chief financial officer, the president and any vice president or more senior
officer of such Person.

     "Standstill Agreement" has the meaning assigned to such term in the first
paragraph of this Standstill Agreement.

     "Standstill Period" means the period commencing on the Effective Date and
ending on the Termination Date.

     "Subsidiary Guarantors" means all of the Subsidiaries party to Subsidiary
Guaranties.

                                        4

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       "Termination Date" means the earlier of

       (i)    July 17, 2002; and

       (ii)   the date of occurrence of a Termination Event.

       "Termination Event" means

       (i)    the failure by the Company to perform any covenant set forth in
              Section 5(b);

       (ii)   the failure of any representation or warranty in Section 6 to be
              true and correct;

       (iii)  the occurrence of any Default or Event of Default other than an
              Existing Event of Default;

       (iv)   on or after the Effective Date the Company or any Subsidiary is
              (A) in default (as principal or as guarantor or other surety) in
              payment of any principal of or premium or make-whole amount or
              interest on any Debt (other than the Heller Debt, the Winthrop
              Lease and the Notes) that is outstanding in an aggregate principal
              amount of at least $5,000,000 beyond any period of grace provided
              with respect thereto, or (B) in default in the performance of or
              compliance with any term of any evidence of any Debt in an
              aggregate outstanding principal amount of at least $5,000,000
              (other than the Heller Debt, the Winthrop Lease and the Notes) or
              of any mortgage, indenture or other agreement relating thereto or
              any other condition exists, and as a consequence of such default
              or condition such Debt has become, or has been declared (or one or
              more Persons are entitled to declare such Debt to be), due and
              payable before its stated maturity or before its regularly
              scheduled dates or payment; or

       (v)    as a consequence of the occurrence or continuation of any event or
              condition, (x) the Company or any Subsidiary has become or is
              obligated on or after the Effective Date to purchase or repay Debt
              (including, without limitation, the Heller Debt) before its
              regular maturity or before its regularly scheduled dates of
              payment in an aggregate outstanding principal amount of at least
              $5,000,000, or (y) one or more Persons have the right on or after
              the Effective Date to require the Company or any Subsidiary to
              purchase or repay Debt or other amounts (including, without
              limitation, the Heller Debt and amounts in respect of the Winthrop
              Lease) before its regular maturity or before its regularly
              scheduled dates or payment in an aggregate outstanding principal
              amount of at least $5,000,000.

                                        5

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       "2001 Note Purchase Agreement" has the meaning assigned to such term in
the third "whereas" clause of this Standstill Agreement.

       "2001 Noteholders" means the parties listed in Schedule C hereto.

       "Winthrop Lease" means the Lease Agreement dated October 3, 2001 from
Winthrop Resources Corporation to Seitel, Inc. with respect to computer and
related equipment.

2.     STANDSTILL PERIOD.

       The Noteholders agree, during the Standstill Period, to forbear from
exercising any rights and remedies they may have under any or all of the Note
Purchase Agreements or any of the Notes or any of the other Financing Documents
solely as a result of the existence or occurrence of any Existing Event of
Default. The Company acknowledges that upon the termination of the Standstill
Period, such forbearance by the Noteholders shall terminate and the Noteholders
may immediately exercise, without further notice, any one or more of such rights
and remedies without notice or demand in respect of any Default, Event of
Default or Existing Event of Default. The Company has indicated that during the
Standstill Period it may identify asset sales or alternative financing that will
enable it to meet certain of its immediate cash needs, and the Company has
indicated that it will present for Noteholder approval any such proposed asset
sales or financing arrangements.

3.     AMENDMENTS.

       (a) Each of the Note Purchase Agreements and the Notes is hereby amended
to effect an increase in the interest rate payable on each Note of twenty-five
basis points (0.25%) per annum and to change each reference to the interest rate
applicable to any Note to such increased interest rate, in each case with
respect to the period from June 21, 2002 through and including July 17, 2002. No
other action on the part of the Company (including no physical notation on any
Note) shall be necessary to give effect to this amendment.

       (b) The 2001 Note Purchase Agreement and the Notes issued pursuant
thereto are hereby amended so that, in the case of each cross reference therein
to any of Sections or Schedules 5 to 22 inclusive, each such cross reference
shall be deemed to be a cross reference to Section or Schedule 6 to 23
inclusive, respectively.

4.     NOTICE OF TERMINATION EVENT.

       The Company shall give each of the Noteholders immediate written notice
of the occurrence of any Termination Event.

                                        6

<PAGE>

5.     ADDITIONAL COVENANTS OF COMPANY.

       (a)   Override of Certain Financial Covenants. During the period from the
Effective Date through July 17, 2002, Sections 10.3 through 10.7 and Section
10.9 of the 1995 Note Purchase Agreement and the 1999 Note Purchase Agreement,
and Sections 11.3 through 11.7 and Section 11.9 of the 2001 Note Purchase
Agreement, shall be suspended and, in lieu thereof, the Company shall, and shall
cause its Subsidiaries to, comply with the provisions of Section 5(b) of this
Standstill Agreement.

       (b)   Supplemental Covenants of the Company. During the period from the
Effective Date through July 17, 2002, the Company shall not, and shall not
permit any Subsidiary (including, without limitation, any Subsidiary organized
under the laws of, or otherwise existing or domiciled in, Canada or any province
or other jurisdiction therein) to:

             (i)   make, directly or indirectly, any Restricted Payment
       (references to "Restricted Subsidiaries" in the definition of "Restricted
       Payment" being deemed to be references to "Subsidiaries" except for the
       second reference to "Restricted Subsidiaries" in the parenthetical
       expression in paragraph (a) of the definition of "Restricted Payment");

             (ii)  make, directly or indirectly, any Restricted Investment
       (provided that the Company and the Subsidiaries may make Restricted
       Investments constituting unsubordinated debt obligations of Unrestricted
       Subsidiaries in an aggregate amount not to exceed $1,500,000 during the
       period from June 24, 2002 through and including July 17, 2002);

             (iii) create, incur or assume any Debt;

             (iv)  effectuate any Transfer (including, without limitation, any
       Transfer involving the assets of DDD Energy, Inc.) except for (a)
       Transfers of inventory in the ordinary course of business, (b) Transfers
       to Unrestricted Subsidiaries permitted pursuant to clause (ii) above, (c)
       Transfers to Wholly-Owned Restricted Subsidiaries in the ordinary course
       of business, (d) Transfers to Affiliates that constitute joint ventures
       of the Company or its Subsidiaries with unrelated third parties, which
       Transfers are made in the ordinary course of business and pursuant to
       preexisting contractual obligations of the Company and the Subsidiaries
       and (e) Transfers that have been approved by the Required Noteholders in
       writing;

             (v)   settle, sell, compromise and/or discount any loans made to
       any officers, directors and/or employees of the Company or any
       Subsidiary;

                                        7

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              (vi)   merge or consolidate with any other Person;

              (vii)  pay any bonuses or advances on commissions to any Senior
       Officer of the Company or any Subsidiary, other than payments
       previously-contracted for that are due and payable during the Standstill
       Period and are disclosed to the Noteholders in writing prior to the
       Effective Date; or

              (viii) create, incur or assume any Lien upon any of the property
       or assets of the Company or any Subsidiary, whether now owned or
       hereafter acquired, except for those Liens permitted by Section 10.4(a)
       through (i) of the 1995 Note Purchase Agreement and the 1999 Note
       Purchase Agreement, and Section 11.4(a) through (i) of the 2001 Note
       Purchase Agreement.

       (c)    Financial Advisor. The Company agrees to the hiring by the
Noteholders' special counsel of Crossroads, LLC to act as financial advisor (the
"Financial Advisor") to the Noteholders' special counsel and the Company agrees
to pay the fees and expenses of the Financial Advisor in accordance with that
engagement letter between Bingham Dana LLP (now Bingham McCutchen LLP) and the
Financial Advisor dated June 11, 2002 which engagement letter has been
acknowledged and agreed to by the Company (the "Financial Advisor Engagement
Agreement"). The Company shall provide the Financial Advisor with full onsite
access to its books and records and the opportunity to discuss the Company's
financial condition, performance, financial statements and other matters
pertinent to the Noteholders' investment in the Company with its officers,
directors, independent accountants and financial advisors to permit the
Financial Advisor to fully investigate any matter that arises during its review
of the financial information of the Company and its Subsidiaries. The Financial
Advisor shall have no duty to share its work product with, or accept
instructions from, the Company or any other Person working on its behalf.

6.     REPRESENTATIONS AND WARRANTEES.

       To induce the Noteholders to enter into this Standstill Agreement, the
Company represents and warrants, as of the Effective Date, as follows:

              (a)    the Company is a corporation duly organized, validly
       existing and in good standing under the laws of the state of Delaware;

              (b)    each of the Subsidiaries is an organization duly organized,
       validly existing and in good standing under the laws of the jurisdiction
       of its organization;

                                        8

<PAGE>

          (c) the execution and delivery of this Standstill Agreement is within
     the corporate powers of the Company and each Subsidiary Guarantor, has been
     duly authorized by the Company and each Subsidiary Guarantor and constitute
     a valid and binding obligation of the Company and each Subsidiary
     Guarantor, enforceable in accordance with its terms, except that such
     enforceability may be limited by bankruptcy, insolvency, reorganization,
     moratorium or other similar laws affecting the enforceability of creditors'
     rights generally and except that such enforceability is subject to the
     availability of equitable remedies;

          (d) The execution and delivery of this Standstill Agreement does not
     conflict with, result in any breach of any of the provisions of, constitute
     a default under, or result in the creation of any Lien upon any property of
     the Company or any Subsidiary Guarantor under the provisions of, any
     agreement, charter instrument, bylaw or other instrument to which the
     Company or any Subsidiary Guarantor is a party or by which the Company, any
     of its Subsidiaries, or any of their respective properties may be bound;

          (e) each of the Notes, the Note Purchase Agreements and the other
     Financing Documents to which the Company and each Subsidiary Guarantor is a
     party, as modified by this Standstill Agreement, constitutes a valid and
     binding obligation of the Company and such Subsidiary Guarantor party
     thereto, enforceable in accordance with its terms, except that such
     enforceability may be limited by bankruptcy, insolvency, reorganization,
     moratorium or other similar laws affecting the enforceability of creditors'
     rights generally and except that such enforceability is subject to the
     availability of equitable remedies; and

          (f) except with respect to Existing Events of Default, there are, to
     the best present actual knowledge of the Company, no Defaults or Events of
     Default in existence on the Effective Date (although the Company continues
     its investigation and diligence into certain matters that may reveal the
     existence of additional Defaults or Events of Default).

7.   NONWAIVER AND NO AMENDMENT.

     Except as expressly set forth herein, the terms of this Standstill
Agreement shall not operate as a waiver by any of the Noteholders of, or
otherwise prejudice, the Noteholders' rights, remedies or powers under the
Notes, the Note Purchase Agreements, the other Financing Documents or applicable
law. With respect to any Event of Default under any of the Note Purchase
Agreements, as modified by this Standstill Agreement, other than any Existing
Event of Default, any of the Noteholders may exercise the rights, remedies and
powers provided in such Note Purchase Agreement and the other Financing
Documents in accordance with the terms of such documents regardless of whether
such Event of Default shall exist on

                                       9

<PAGE>

the date hereof or come into existence during the Standstill Period. Except to
the extent expressly provided for herein, this Standstill Agreement shall not
operate to waive or otherwise prejudice any rights which the Noteholders may
have against the Company, any party to a Subsidiary Guaranty or any other Person
arising under the Note Purchase Agreements, the Notes, the other Financing
Documents or otherwise.

     Except as expressly provided herein, no terms or provisions of the Note
Purchase Agreements, the Notes or the other Financing Documents are modified or
changed by this Standstill Agreement, and all of the terms and provisions of the
Note Purchase Agreements, the Notes and the other Financing Documents shall
continue in full force and effect. The Company and the parties to the Subsidiary
Guaranties hereby acknowledge and reaffirm all of their respective obligations
and duties under each of the Note Purchase Agreements, the Notes and the other
Financing Documents to which each is a party, as each such Financing Document is
modified by this Standstill Agreement.

8.   EFFECTIVE DATE.

     The "Effective Date" shall be the first date on which the Company and the
Required Noteholders shall have executed and delivered this Standstill
Agreement.

9.   EXPENSES AND FEES.

     The Company hereby agrees to pay all reasonable costs and expenses of the
Noteholders (it being understood and agreed by the Company that the Noteholders
shall have wide latitude on the scope and depth of legal analysis they obtain
from their legal and financial advisors to evaluate, explore, and protect
Noteholder interests regarding the Company and the Notes in light of existing
defaults, accounting and executive officer irregularities, and related matters
affecting the Company's business plan, viability, and restructuring prospects),
including, without limitation, the fees and expenses of Bingham McCutchen LLP,
special counsel to the Noteholders, and Crossroads, LLC, the Noteholders'
Financial Advisor, and also including the reasonable out-of-pocket travel and
other expenses of the Noteholders incurred in connection with this Standstill
Agreement and the collection of any sum owed to any of the Noteholders by the
Company and in otherwise assessing, analyzing, evaluating, protecting,
asserting, defending or enforcing any rights or remedies which are or may be
available to the Noteholders, including, without limitation, representatives of
the Noteholders in any bankruptcy proceeding.

10.  HEADINGS.

     All headings and captions preceding the text of the several Sections of
this Standstill Agreement are intended solely for the convenience of reference
and shall

                                       10

<PAGE>

not constitute a part of this Standstill Agreement nor shall they affect its
meaning, construction or effect.

11.  ENTIRE AGREEMENT.

     This Standstill Agreement, the Note Purchase Agreement, the Notes and the
other Financing Documents, as amended to the date hereof, embody the entire
agreement and understanding between the Noteholders, the Company and the parties
to the Subsidiary Guaranties and supersede all prior agreements and
understandings relating to the subject matter hereof and thereof.

12.  GOVERNING LAW.

     This Standstill Agreement shall be governed by, and construed in accordance
with, the internal laws of the State of New York.

13.  DIRECTLY OR INDIRECTLY.

     Where any provision in this Standstill Agreement refers to action to be
taken by any Person, or which such Person is prohibited from taking, such
provision shall be applicable whether such action is taken directly or
indirectly by such Person, including actions taken by or on behalf of any
partnership or limited liability company in which such Person is a general
partner or managing member, as applicable.

14.  COUNTERPARTS.

     This Standstill Agreement may be executed by the parties hereto in separate
counterparts, each of which when so executed shall be deemed to be an original
and all of which taken together shall constitute one and the same agreement. An
executed copy of this Standstill Agreement sent by facsimile shall be effective
as an original.

15.  NOTICES.

     All communications under this Standstill Agreement shall be made in
accordance with the Note Purchase Agreements.

     [Remainder page intentionally left blank. Next page is signature page.]

                                       11

<PAGE>

         IN WITNESS WHEREOF, the parties hereto have caused this Standstill
Agreement to be executed by their authorized officers as of the date first
written above.

                                         SEITEL, INC.

                                         By  /s/ Kevin Fiur
                                            ------------------------------------
                                         Name:  Kevin Fiur
                                         Title: President and Chief Executive
                                                Officer

                                         PRINCIPAL LIFE INSURANCE COMPANY
                                         By:  Principal Capital Management,
                                              LLC, a Delaware limited
                                              liability company, its
                                              authorized signatory

                                         By: /s/ Debra Svoboda Epp
                                            ------------------------------------
                                            Name:  Debra Svoboda Epp
                                            Title: Counsel

                                         By: /s/ Jon C. Henry
                                            ------------------------------------
                                            Name:  Jon C. Henry
                                            Title: Counsel

                                         PRINCIPAL LIFE INSURANCE COMPANY, ON
                                         BEHALF OF ONE OR MORE SEPARATE ACCOUNTS
                                         By:  Principal Capital Management,
                                              LLC, a Delaware limited
                                              liability company, its
                                              authorized signatory

                                         By: /s/ Debra Svoboda Epp
                                            ------------------------------------
                                            Name:  Debra Svoboda Epp
                                            Title: Counsel

                                         By: /s/ Jon C. Henry
                                            ------------------------------------
                                            Name:  Jon C. Henry
                                            Title: Counsel

<PAGE>

                                        CGU LIFE INSURANCE COMPANY OF AMERICA,
                                        a Delaware corporation (formerly known
                                        as Commercial Union Life Insurance
                                        Company of America)

                                        By:   Principal Capital Management, LLC,
                                              a Delaware limited liability
                                              company, its attorney in fact

                                        By: /s/ Debra Svoboda Epp
                                           -------------------------------------
                                           Name:  Debra Svoboda Epp
                                           Title: Counsel

                                        By: /s/ Jon C. Henry
                                           -------------------------------------
                                           Name: Jon C. Henry
                                           Title: Counsel

                                        ALLSTATE LIFE INSURANCE COMPANY

                                        By /s/ unrecognizable signature
                                          ---------------------------------
                                        Name:  unknown
                                        Title: Authorized Signatory

                                        By /s/ unrecognizable signature
                                          ---------------------------------
                                        Name:  unknown
                                        Title: Authorized Signatory

                                        ALLSTATE LIFE INSURANCE COMPANY OF NEW
                                        YORK

                                        By /s/ unrecognizable signature
                                          ---------------------------------

<PAGE>

                                 Name:  unknown
                                 Title: Authorized Signatory

                                 By /s/ unrecognizable signature
                                    ----------------------------
                                 Name:  unknown
                                 Title: Authorized Signatory

                                 MASSACHUSETTS MUTUAL LIFE
                                 INSURANCE COMPANY
                                 By:    David L. Babson & Company Inc.
                                        as Investment Adviser

                                 By /s/ Richard C. Morrison
                                    -------------------------------------------
                                 Name:  Richard C. Morrison
                                 Title: Managing Director

                                 C.M. LIFE INSURANCE COMPANY
                                 By:    David L. Babson and Company Inc.
                                        as Investment Sub-Adviser

                                 By /s/ Richard C. Morrison
                                    -------------------------------------------
                                 Name:  Richard C. Morrison
                                 Title: Managing Director

                                 MASSMUTUAL ASIA LIMITED
                                 By:    David L. Babson & Company Inc.
                                        as Investment Adviser

                                 By /s/ Richard C. Morrison
                                    -------------------------------------------
                                 Name:  Richard C. Morrison
                                 Title: Managing Director

                                 THE GUARDIAN INSURANCE & ANNUITY COMPANY, INC.

                                 By  /s/ Thomas M. Donohue
                                     ------------------------------------------
                                 Name:  Thomas M. Donohue
                                 Title: Managing Director

                                 FORT DEARBORN LIFE INSURANCE COMPANY
                                 By:    Guardian Investor Services LLC

<PAGE>

                       By  /s/ Thomas M. Donohue
                           -----------------------------------------------------
                       Name:  Thomas M. Donohue
                       Title: Managing Director

                       THE GUARDIAN LIFE INSURANCE COMPANY OF AMERICA

                       By  /s/ Thomas M. Donohue
                           -----------------------------------------------------
                       Name:  Thomas M. Donohue
                       Title: Managing Director

                       BERKSHIRE LIFE INSURANCE COMPANY OF AMERICA

                       By  /s/ Thomas M. Donohue
                           -----------------------------------------------------
                       Name:  Thomas M. Donohue
                       Title: Managing Director

                       J. ROMEO & CO. AS NOMINEE FOR MONY LIFE INSURANCE COMPANY

                       By /s/ Barbara J. Walsh
                          --------------------------------------------------
                       Name:  Barbara J. Walsh
                       Title: Authorized Signatory

                       J. ROMEO & CO. AS NOMINEE FOR MONY LIFE INSURANCE
                       COMPANY OF AMERICA

                       By /s/ Barbara J. Walsh
                          --------------------------------------------------
                       Name:  Barbara J. Walsh
                       Title: Authorized Signatory

                       PHOENIX LIFE INSURANCE COMPANY

                       By /s/ Christopher M. Wilkos
                          --------------------------------------------------
                       Name:  Christopher M. Wilkos
                       Title: Senior Vice President, Corporate
                              Portfolio Management

<PAGE>

                                    UNITED OF OMAHA LIFE INSURANCE COMPANY

                                    By /s/ Edwin H. Garrison, Jr.
                                       ----------------------------------------
                                    Name:  Edwin H. Garrison, Jr.
                                    Title: First Vice President

                                    RELIASTAR LIFE INSURANCE COMPANY
                                    By: ING Investment Management, LLC, as Agent

                                    By /s/ James V. Wittich
                                       -----------------------------------------
                                    Name:  James V. Wittich
                                    Title: Senior Vice President

                                    NORTHERN LIFE INSURANCE COMPANY
                                    By: ING Investment Management, LLC, as Agent

                                    By /s/ James V. Wittich
                                       -----------------------------------------
                                    Name:  James V. Wittich
                                    Title: Senior Vice President

                                    RELIASTAR LIFE INSURANCE COMPANY OF NEW YORK
                                    By: ING Investment Management LLC, as Agent

                                    By /s/ James V. Wittich
                                       -----------------------------------------
                                    Name:  James V. Wittich
                                    Title: Senior Vice President

                                    SECURITY CONNECTICUT LIFE INSURANCE COMPANY
                                    By: ING Investment Management LLC, as Agent

                                    By /s/ James V. Wittich
                                       -----------------------------------------
                                    Name:  James V. Wittich

<PAGE>

                                     Title: Senior Vice President

Accepted and Agreed:

SEITEL DATA CORP.

By /s/ Kevin Fiur
   ---------------------------------
Name:  Kevin Fiur
Title: President and Chief Executive Officer

SEITEL DATA, LTD.
By: Seitel Delaware, Inc., general partner

By /s/ Kevin Fiur
   ---------------------------------
Name:  Kevin Fiur
Title: President and Chief Executive Officer

N360X, L.L.C.
By: Seitel Management, Inc.,
    managing member

By /s/ Kevin Fiur
   ---------------------------------
Name:  Kevin Fiur
Title: President and Chief Executive Officer

SEITEL MANAGEMENT, INC.

By /s/ Kevin Fiur
   ---------------------------------
Name:  Kevin Fiur
Title: President and Chief Executive Officer

SEITEL GEOPHYSICAL, INC.
DDD ENERGY, INC.
SEITEL GAS & ENERGY CORP.
SEITEL POWER CORP.
SEITEL NATURAL GAS, INC.
MATRIX GEOPHYSICAL, INC.
EXSOL, INC.
DATATEL, INC.
SEITEL OFFSHORE CORP.
SEITEL INTERNATIONAL, INC.
AFRICAN GEOPHYSICAL, INC.
GEO-BANK, INC.
ALTERNATIVE COMMUNICATION

<PAGE>

 ENTERPRISES, INC.
SEITEL DELAWARE, INC.

By /s/ Kevin Fiur
   ---------------------------------
Name:  Kevin Fiur
Title: President and Chief Executive Officer

<PAGE>

                                    EXHIBIT A
                           EXISTING EVENTS OF DEFAULT

1995 Note Purchase Agreement

1. The failure of the Company to comply with Section 10.2 for the period of four
consecutive fiscal quarters ended on March 31, 2002.

1999 Note Purchase Agreement

1. The failure of the Company to comply with Section 10.2 for the period of four
consecutive fiscal quarters ended on March 31, 2002.

2. The failure of the Company to comply with Section 10.7(a) by making
Restricted Payments and/or Restricted Investments during the fiscal quarter
ending on March 31, 2002 that exceeded the permissible amount under Section
10.7(a) by not more than $10,000,000.

2001 Note Purchase Agreement

1. The failure of the Company to comply with Section 11.2 for the period of four
consecutive fiscal quarters ended on March 31, 2002.

<PAGE>

                                   SCHEDULE A
                                1995 NOTEHOLDERS

Massachusetts Mutual Life Insurance Company
SunAmerica Life Insurance Company
First SunAmerica Life Insurance Company
MONY Life Insurance Company
MONY Life Insurance Company of America
United of Omaha Life Insurance Company
Pan-American Life Insurance Company

<PAGE>

                                   SCHEDULE B
                                1999 NOTEHOLDERS

Principal Life Insurance Company
Principal Life Insurance Company, on behalf of one or more separate accounts
CGU Life Insurance Company of America
Allstate Life Insurance Company
Allstate Life Insurance Company of New York
Provident Life and Accident Insurance Company
The Paul Revere Life Insurance Company
Massachusetts Mutual Life Insurance Company
C.M. Life Insurance Company
United of Omaha Life Insurance Company
Phoenix Life Insurance Company
Reliastar Life Insurance Company
Northern Life Insurance Company
Reliastar Life Insurance Company of New York
Security Connecticut Life Insurance Company
Trustmark Life Insurance Co.
Pan-American Life Insurance Company
Republic Western Insurance Company
Oxford Life Insurance Company
United Life Insurance Company

<PAGE>

                                   SCHEDULE C
                                2001 NOTEHOLDERS

The Guardian Insurance & Annuity Company
Fort Dearborn Life Insurance Company
The Guardian Life Insurance Company of America
Berkshire Life Insurance Company of America
MONY Life Insurance Company
Nationwide Life Insurance Company
Nationwide Life and Annuity Insurance Company
Connecticut General Life Insurance Company
Life Insurance Company of North America
Massachusetts Mutual Life Insurance Company
C.M. Life Insurance Company
MassMutual Asia Limited
Allstate Life Insurance Company
Principal Life Insurance Company
Phoenix Life Insurance Company
American Investors Life Insurance Company<PAGE>
                                                                   EXHIBIT 10.56

                               NOTEHOLDER CONSENT

     This NOTEHOLDER CONSENT (this "Consent"), dated as of July 15, 2002, is
among SEITEL, INC. (the "Company"), a Delaware corporation, and each of the
investors listed on the signature pages hereto (together with successors and
assigns of each, a "Noteholder," and collectively, the "Noteholders").
Capitalized terms have the respective meanings ascribed thereto in Section 1
hereof.

                              W I T N E S S E T H:

     WHEREAS, each of the 1995 Noteholders and the Company are party to those
certain separate Note Purchase Agreements dated as of December 28, 1995
(collectively, as amended, the "1995 Note Purchase Agreement"), providing for
the sale by the Company and the purchase by the 1995 Noteholders of the
Company's Series B Notes and Series C Notes; and each of the 1999 Noteholders
and the Company are party to those certain separate Note Purchase Agreements
dated as of February 12, 1999 (collectively, as amended, the "1999 Note Purchase
Agreement"), providing for the sale by the Company and the purchase by the 1999
Noteholders of the Company's Series D Notes, Series E Notes and Series F Notes;
and each of the 2001 Noteholders and the Company are party to those certain
separate Note Purchase Agreements dated as of October 15, 2001 (collectively,
the "2001 Note Purchase Agreement"), providing for the sale by the Company and
the purchase by the 2001 Noteholders of the Company's Series G Notes, Series H
Notes and Series I Notes;

     WHEREAS, the 1995 Note Purchase Agreement, the 1999 Note Purchase Agreement
and the 2001 Note Purchase Agreement are collectively referred to herein as the
"Note Purchase Agreements;" and

     WHEREAS, the Series B Notes, the Series C Notes, the Series D Notes, the
Series E Notes, the Series F Notes, the Series G Notes, the Series H Notes and
the Series I Notes are collectively referred to herein as the "Notes;" and

     WHEREAS, on the date hereof, the Company's records indicate that each
Noteholder is the registered owner, in its own or its nominee's name, of one or
more of the Notes; and

     WHEREAS, the DDD Energy, Inc., a Restricted Subsidiary, desires to Transfer
certain gas and oil properties and other assets held by it to Rising Star
Energy, L.L.C. (the "Purchaser") pursuant to that Purchase and Sale Agreement,

<PAGE>

dated as of July 4, 2002, between DDD Energy, Inc and the Purchaser, a copy of
which is attached hereto as Exhibit A (the "PSA");

     WHEREAS, pursuant to the terms of the Note Purchase Agreements and that
Standstill, Forbearance and Amendment Agreement dated as of June 21, 2002 among
the Company and the Noteholders, the consent of the Required Holders under each
of the Note Purchase Agreements is a condition precedent to the proposed
Transfer of assets of DDD Energy, Inc.; and

     WHEREAS, the Company has requested that the Noteholders agree and consent
to such Transfer and, subject to the terms and conditions contained herein, the
Noteholders so agree and consent.

     NOW, THEREFORE, in consideration of the matters referred to above, the
mutual covenants set forth herein, and other good and valuable consideration,
the receipt and sufficiency of which are hereby acknowledged, the parties hereto
agree as follows:

1.   DEFINITIONS.

     The following terms listed below have the meanings set forth below.
Capitalized terms used and not otherwise defined herein shall have the meanings
assigned to them in the Note Purchase Agreements.

     "Company" has the meaning assigned to such term in the first paragraph of
this Consent.

     "Consent" has the meaning assigned to such term in the first paragraph of
this Consent.

     "1995 Note Purchase Agreement" has the meaning assigned to such term in the
first "whereas" clause of this Consent.

     "1999 Note Purchase Agreement" has the meaning assigned to such term in the
second "whereas" clause of this Consent.

     "Noteholders" has the meaning assigned to such term in the first paragraph
hereof.

     "Note Purchase Agreements" has the meaning assigned to such term in the
second "whereas" clause of this Consent.

     "Notes" has the meaning assigned to such term in the third "whereas" clause
of this Consent.

                                        2

<PAGE>

     "PSA" - has the meaning assigned to such term in the fifth "whereas" clause
of this Consent.

     "Purchaser" - has the meaning assigned to such term in the fifth "whereas"
clause of this Consent.

     "Required Noteholders" shall mean the holders of a majority of the
principal amount of the Notes then outstanding issued under each of the 1995
Note Purchase Agreement, the 1999 Note Purchase Agreement and the 2001 Note
Purchase Agreement.

     "2001 Note Purchase Agreement" has the meaning assigned to such term in the
third "whereas" clause of this Consent.

2.   CONSENT.

     Each Noteholder hereby consents, with respect to the Notes held by it, to
the Transfer of (i) the "Acquired Assets" and, (ii) to the extent the Purchase
Option is exercised as provided for in Section 1.03 of the PSA, the "Excluded
Assets" (with all terms used but not defined in this Section II having the
meaning ascribed to such terms in the PSA) to the Purchaser, pursuant to the
terms of the PSA, in accordance with the following conditions:

     a.   Use of Proceeds.

          Up to $9,000,000.00 of the Purchase Price may be used by the Company
     in accordance with the Projected Cash Receipts & Disbursements (through
     September 27, 2002) dated June 20, 2002, a copy of which is attached hereto
     as Exhibit "A" as the same may be amended or updated, consistent, for the
     applicable period, with the "Standstill, Forbearance and Amendment
     Agreement" dated as of June 21, 2002 and executed on July 9, 2002, as may
     be extended and/or amended (the "Standstill Agreement").

     b.   Interest Payable Upon Closing

          An amount equal to the interest obligations due on the Notes (all
     series) through the Closing Date under the PSA shall be paid directly to
     the Noteholders (or an account or accounts to be designated by the
     Noteholders, for further distribution to the Noteholders) out of the
     Purchase Price at the Closing.

     c.   Escrow Remainder

          The remainder of the Purchase Price after giving effect to the
     provisions of paragraphs "a" and "b" above and, if applicable, the Option
     Price, shall be owned by the Company and held in an interest bearing escrow
     account ("Escrow") and not disbursed by the escrow agent ("Escrow Agent")

                                        3

<PAGE>

     except upon the earlier of (i) twenty (20) days prior written notice (a
     "Notice") to the Noteholders (the "Notice Period") and (ii) the consent of
     the Noteholders, as provided below; such Notice to be delivered to the
     Noteholders by written notice given to Bingham McCutchen LLP, special
     counsel to the Noteholders, and Crossroads LLC, the Noteholders' Financial
     Advisors. In each such Notice, the Company shall provide the intended uses
     and respective amounts of the proposed expenditures out of the Escrow and
     shall state that such expenditure is consistent with the Standstill
     Agreement. The Noteholders shall have five (5) business days to provide
     written consent with respect to the proposed expenditures; in the event the
     Noteholders do not timely consent to any disbursement as requested, the
     Escrow Agent shall refrain from disbursing the objected-to amount until the
     expiration of the Notice Period.

                           (1) To the extent the Noteholders have procured a
                  binding order of a court of competent jurisdiction prior to
                  the expiration of the Notice Period prohibiting the
                  disbursement, the Escrow Agent and the Company shall be
                  prohibited from making such disbursement pending disposition
                  by written agreement with the Noteholders or court order.

                           (2) To the extent the Noteholders have not procured
                  such a binding order, then, upon expiration of the Notice
                  Period, the Escrow Agent and the Company shall be authorized
                  to make the disbursement provided for in that Notice, provided
                  however, that as a condition to such authorization and
                  disbursement, the Company shall pay to the Noteholders (or an
                  account or accounts to be designated by the Noteholders, for
                  further distribution to the Noteholders) no later than
                  coterminously with the disbursement, the amount of interest
                  due on the Notes (all series) through and including the
                  proposed disbursement date.

     d.           Two Month Interest Cycle

                  Notwithstanding the terms of the Note Purchase Agreements and
     the Notes, from and after the Closing Date, ratable interest on the Notes
     shall be paid every two (2) months on a common date commencing on the first
     business day of the third full month following the Closing on the PSA
     (e.g., if Closing is July 31, the first two month payment will be October 1
     for the period through and including September 30), and continuing on the
     first business day of every second month thereafter through the conclusion
     of the respective terms of the Notes as provided in the Note Purchase
     Agreement.

     e.           Calculation of Covenant Compliance

                                       4

<PAGE>

                  In respect of the calculation for covenant compliance under
     the Note Purchase Agreements and the Notes, the Acquired Assets and
     Excluded Assets and the liabilities attributed to them shall be excluded in
     the calculation of covenant compliance.

     f.           Consent to be Delivered to Purchaser

                  The Noteholders specifically authorize the Company to deliver,
     in the Company's discretion, a copy of this Consent to the Purchaser.

3.   EXPENSES AND FEES.

     The Company agrees to pay all reasonable fees and expenses of the
Noteholders, including, without limitation, those of Bingham McCutchen LLP,
special counsel to the Noteholders, and Crossroads, LLC, the Noteholders'
Financial Advisor, incurred in connection with this Consent and the truncations
related thereto.

4.   REPRESENTATIONS OF THE COMPANY.

     The Company hereby represents and warrants to the Noteholders that the
Purchaser is not an Affiliate of the Company, and that there are no other
material agreements or arrangements between the Company and/or the Subsidiaries
on the one hand and the Purchaser on the other with respect to the sale of the
DDD Energy, Inc. assets.

5.   HEADINGS.

     All headings and captions preceding the text of the several Sections of
this Consent are intended solely for the convenience of reference and shall not
constitute a part of this Consent nor shall they affect its meaning,
construction or effect.

6.   COUNTERPARTS.

     This Consent may be executed by the parties hereto in separate
counterparts, each of which when so executed shall be deemed to be an original
and all of which taken together shall constitute one and the same agreement. An
executed copy of this Consent sent by facsimile shall be effective as an
original.

     [Remainder page intentionally left blank. Next page is signature page.]

                                       5

<PAGE>

         IN WITNESS WHEREOF, each party hereto has caused this Consent to be
executed by its authorized officers as of the date first written above.

                                      PRINCIPAL LIFE INSURANCE
                                      COMPANY
                                      By: Principal Capital
                                          Management, LLC, a
                                          Delaware limited liability
                                          company, its authorized signatory

                                      By: /s/ Debra Svoboda Epp
                                         ---------------------------------------
                                         Name:  Debra Svoboda Epp
                                         Title: Counsel

                                      By: /s/ Jon C. Henry
                                         ---------------------------------------
                                         Name:  Jon C. Henry
                                         Title: Counsel

                                      PRINCIPAL LIFE INSURANCE
                                      COMPANY, ON BEHALF OF ONE
                                      OR MORE SEPARATE ACCOUNTS
                                      By: Principal Capital
                                          Management, LLC, a
                                          Delaware limited liability
                                          company, its authorized signatory

                                      By: /s/ Debra Svoboda Epp
                                         ---------------------------------------
                                         Name:  Debra Svoboda Epp
                                         Title: Counsel

                                      By: /s/ Jon C. Henry
                                         ---------------------------------------
                                         Name:  Jon C. Henry
                                         Title: Counsel

<PAGE>

                                       -2-

                                       CGU LIFE INSURANCE COMPANY OF AMERICA, a
                                       Delaware corporation (formerly
                                       known as Commercial
                                       Union Life Insurance Company of America)

                                       By: Principal Capital Management, LLC,
                                           a Delaware limited liability company,
                                           its attorney in fact

                                       By: /s/ Debra Svoboda Epp
                                          --------------------------------------
                                          Name:  Debra Svoboda Epp
                                          Title: Counsel

                                       By: /s/ Jon C. Henry
                                          --------------------------------------
                                          Name:  Jon C. Henry
                                          Title: Counsel

                                       ALLSTATE LIFE INSURANCE COMPANY

                                       By /s/ W.R. Schmidt
                                         ---------------------------------------
                                       Name:  W.R. Schmidt
                                       Title: Authorized Signatory

                                       By /s/ Pat Wilson
                                          --------------------------------------
                                       Name:  Pat Wilson
                                       Title: Authorized Signatory

                                       ALLSTATE LIFE INSURANCE COMPANY OF NEW
                                       YORK

<PAGE>

                                       -3-

                                     By /s/ W.R. Schmidt
                                        ----------------------------------------
                                     Name:  W.R. Schmidt
                                     Title: Authorized Signatory

                                     By /s/ Pat Wilson
                                        ----------------------------------------
                                     Name:  Pat Wilson
                                     Title: Authorized Signatory

                                     MASSACHUSETTS MUTUAL LIFE INSURANCE COMPANY
                                     By: David L. Babson & Company Inc.
                                         as Investment Adviser

                                     By /s/ Richard C. Morrison
                                        ----------------------------------------
                                     Name:  Richard C. Morrison
                                     Title: Managing Director

                                     C.M. LIFE INSURANCE COMPANY
                                     By: David L. Babson and Company Inc.
                                         as Investment Sub-Adviser

                                     By /s/ Richard C. Morrison
                                        ----------------------------------------
                                     Name:  Richard C. Morrison
                                     Title: Managing Director

                                     MASSMUTUAL ASIA LIMITED
                                     By: David L. Babson & Company Inc.
                                         as Investment Adviser

                                     By /s/ Richard C. Morrison
                                        ----------------------------------------
                                     Name:  Richard C. Morrison
                                     Title: Managing Director

                                     THE GUARDIAN INSURANCE & ANNUITY COMPANY,
                                     INC.

                                     By /s/ Thomas M. Donohue
                                        ----------------------------------------
                                     Name:  Thomas M. Donohue

<PAGE>

                                       -4-

                                  Title: Managing Director

                                  FORT DEARBORN LIFE INSURANCE COMPANY
                                  By: Guardian Investor Services LLC

                                  By  /s/ Thomas M. Donohue
                                      ------------------------------------------
                                  Name:  Thomas M. Donohue
                                  Title: Managing Director

                                  THE GUARDIAN LIFE INSURANCE COMPANY OF AMERICA

                                  By  /s/ Thomas M. Donohue
                                      ------------------------------------------
                                  Name:  Thomas M. Donohue
                                  Title: Managing Director

                                  BERKSHIRE LIFE INSURANCE COMPANY OF AMERICA

                                  By  /s/ Thomas M. Donohue
                                      ------------------------------------------
                                  Name:  Thomas M. Donohue
                                  Title: Managing Director

                                  J. ROMEO & CO. AS NOMINEE FOR
                                  MONY LIFE INSURANCE COMPANY

                                  By /s/ Barbara J. Walsh
                                     -------------------------------------------
                                  Name:  Barbara J. Walsh
                                  Title: Authorized Signatory

                                  J. ROMEO & CO. AS NOMINEE FOR
                                  MONY LIFE INSURANCE COMPANY OF AMERICA

                                  By /s/ Barbara J. Walsh
                                     -------------------------------------------
                                  Name:  Barbara J. Walsh

<PAGE>

                                      -5-

                                   Title: Authorized Signatory

                                   PHOENIX LIFE INSURANCE COMPANY

                                   By /s/ Christopher M. Wilkos
                                     ------------------------------------------
                                   Name:  Christopher M. Wilkos
                                   Title: Senior Vice President, Corporate
                                          Portfolio Management

                                   UNITED OF OMAHA LIFE INSURANCE COMPANY

                                   By /s/ Edwin H. Garrison, Jr.
                                      -----------------------------------------
                                   Name:  Edwin H. Garrison, Jr.
                                   Title: First Vice President

                                   RELIASTAR LIFE INSURANCE COMPANY

                                   By: ING Investment Management,
                                       LLC, as Agent

                                   By /s/ James V. Wittich
                                      -----------------------------------------
                                   Name:  James V. Wittich
                                   Title: Senior Vice President

                                   NORTHERN LIFE INSURANCE COMPANY

                                   By: ING Investment Management, LLC,
                                       as Agent

                                   By /s/ James V. Wittich
                                      -----------------------------------------
                                   Name:  James V. Wittich
                                   Title: Senior Vice President

                                   RELIASTAR LIFE INSURANCE COMPANY OF NEW YORK

                                   By: ING Investment Management LLC, as Agent

<PAGE>

                                       -6-

                                                By /s/ James V. Wittich
                                                   -----------------------------
                                                Name:  James V. Wittich
                                                Title: Senior Vice President

                                                SECURITY CONNECTICUT LIFE
                                                INSURANCE COMPANY

                                                By:    ING Investment
                                                       Management LLC, as Agent

                                                By /s/ James V. Wittich
                                                   -----------------------------
                                                Name:  James V. Wittich
                                                Title: Senior Vice President

Accepted and Agreed:

SEITEL, INC.

By /s/ Kevin Fiur
   ---------------------------------
Name:   Kevin Fiur
Title:  President and Chief Executive Officer

SEITEL DATA CORP.

By /s/ Kevin Fiur
   ---------------------------------
Name:   Kevin Fiur
Title:  President and Chief Executive Officer

SEITEL DATA, LTD.

By: Seitel Delaware, Inc., general partner

By /s/ Kevin Fiur
   ---------------------------------
Name:   Kevin Fiur
Title:  President and Chief Executive Officer

N360X, L.L.C.
By: Seitel Management, Inc.,
    managing member

By /s/ Kevin Fiur
   ---------------------------------
Name:   Kevin Fiur
Title:  President and Chief Executive Officer

<PAGE>

                                       -7-

SEITEL MANAGEMENT, INC.

By /s/ Kevin Fiur
   ---------------------------------
Name:   Kevin Fiur
Title:  President and Chief Executive Officer

SEITEL GEOPHYSICAL, INC.
DDD ENERGY, INC.
SEITEL GAS & ENERGY CORP.
SEITEL POWER CORP.
SEITEL NATURAL GAS, INC.
MATRIX GEOPHYSICAL, INC.
EXSOL, INC.
DATATEL, INC.
SEITEL OFFSHORE CORP.
SEITEL INTERNATIONAL, INC.
AFRICAN GEOPHYSICAL, INC.
GEO-BANK, INC.
ALTERNATIVE COMMUNICATION
 ENTERPRISES, INC.
SEITEL DELAWARE, INC.

By /s/ Kevin Fiur
   ---------------------------------
Name:   Kevin Fiur
Title:  President and Chief Executive Officer

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