UNITED STATES
                     SECURITIES AND EXCHANGE COMMISSION
                          WASHINGTON, D. C. 20549

                                SCHEDULE 13D

                 UNDER THE SECURITIES EXCHANGE ACT OF 1934
                             AMENDMENT NO. 4 *

                     COMPAGNIE GENERALE DE GEOPHYSIQUE
------------------------------------------------------------------------------

                              (Name of Issuer)

              ORDINARY SHARES OF NOMINAL VALUE TWO EUROS EACH
------------------------------------------------------------------------------

                       (Title of Class of Securities)

                                  [NONE]**
          --------------------------------------------------------
                               (CUSIP Number)

                          STEVEN J. STEINMAN, ESQ.
                FRIED, FRANK, HARRIS, SHRIVER & JACOBSON LLP
                             ONE NEW YORK PLAZA
                          NEW YORK, NEW YORK 10004
                               (212) 859-8000
------------------------------------------------------------------------------

        (Name, Address and Telephone Number of Person Authorized to
                    Receive Notices and Communications)

                               MARCH 14, 2005
          --------------------------------------------------------

          (Date of Event which Requires Filing of this Statement)

If the filing  person has  previously  filed a statement on Schedule 13G to
report the  acquisition  which is the subject of this  Schedule 13D, and is
filing  this  schedule  because of ss. ss.  240.13d-1(e),  240.13d-1(f)  or
240.13d-1(g), check the following box [ ].

NOTE:  Schedules  filed in paper format shall include a signed original and
five copies of the schedule,  including all exhibits.  See ss.240.13d-7 for
other parties to whom copies are to be sent.

*The  remainder  of this cover  page  shall be filled  out for a  reporting
person's  initial  filing on this form with respect to the subject class of
securities,  and for any subsequent amendment containing  information which
would alter disclosures provided in a prior cover page.

The  information  required on the remainder of this cover page shall not be
deemed to be  "filed"  for the  purpose  of  Section  18 of the  Securities
Exchange  Act of 1934 ("Act") or otherwise  subject to the  liabilities  of
that section of the Act but shall be subject to all other provisions of the
Act (however, see the Notes).

--------------------------
** The CUSIP Number for the American  Depositary Shares,  each representing
one  fifth of one  Ordinary  Share of  nominal  value two  euros  each,  is
204386106.



                             SCHEDULE 13D

CUSIP No.         None                                   Page 1 of 10 Pages

1.  NAME OF REPORTING PERSONS.
    I.R.S. IDENTIFICATION NOS. OF ABOVE PERSONS

    ENERGY FUND II GP, LLC

2.  CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP*    (a)  [X]
                                                         (b)  [ ]

3.  SEC USE ONLY


4.  SOURCE OF FUNDS*

        AF

5.  CHECK BOX IF DISCLOSURE OF LEGAL PROCEEDINGS IS 
    REQUIRED PURSUANT TO ITEMS 2(d) or 2(e)                   [ ]


6.  CITIZENSHIP OR PLACE OF ORGANIZATION

        DELAWARE

  NUMBER OF      7. SOLE VOTING POWER

   SHARES           1,777,071

 BENEFICIALLY    8. SHARED VOTING POWER

OWNED BY EACH       

 REPORTING       9. SOLE DISPOSITIVE POWER

PERSON WITH         1,777,071

                10. SHARED DISPOSITIVE POWER

                    

11. AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON

        1,777,071

12. CHECK BOX IF THE AGGREGATE AMOUNT IN ROW (11)             [ ]
    EXCLUDES CERTAIN SHARES*


13. PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW (11)

        15.2%

14. TYPE OF REPORTING PERSON*

        OO


                             SCHEDULE 13D

CUSIP No.         None                                   Page 3 of 10 Pages

1.  NAME OF REPORTING PERSONS.
  
        BEACON ENERGY INVESTORS II, LP

2.  CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP*    (a)  [X]
                                                         (b)  [ ]

3.  SEC USE ONLY


4.  SOURCE OF FUNDS*

        AF

5.  CHECK BOX IF DISCLOSURE OF LEGAL PROCEEDINGS IS 
    REQUIRED PURSUANT TO ITEMS 2(d) or 2(e)                   [ ]


6.  CITIZENSHIP OR PLACE OF ORGANIZATION

        DELAWARE

  NUMBER OF      7. SOLE VOTING POWER

   SHARES           1,777,071

 BENEFICIALLY    8. SHARED VOTING POWER

OWNED BY EACH       

 REPORTING       9. SOLE DISPOSITIVE POWER

PERSON WITH         1,777,071

                10. SHARED DISPOSITIVE POWER

                    

11. AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON

        1,777,071

12. CHECK BOX IF THE AGGREGATE AMOUNT IN ROW (11)             [ ]
    EXCLUDES CERTAIN SHARES*


13. PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW (11)

        15.2%

14. TYPE OF REPORTING PERSON*

        OO


                             SCHEDULE 13D

CUSIP No.         None                                   Page 4 of 10 Pages

1.  NAME OF REPORTING PERSONS.
  
        THE BEACON GROUP ENERGY INVESTMENT FUND II, L.P.

2.  CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP*    (a)  [X]
                                                         (b)  [ ]

3.  SEC USE ONLY


4.  SOURCE OF FUNDS*

        AF

5.  CHECK BOX IF DISCLOSURE OF LEGAL PROCEEDINGS IS 
    REQUIRED PURSUANT TO ITEMS 2(d) or 2(e)                   [ ]


6.  CITIZENSHIP OR PLACE OF ORGANIZATION

        DELAWARE

  NUMBER OF      7. SOLE VOTING POWER

   SHARES           1,748,648

 BENEFICIALLY    8. SHARED VOTING POWER

OWNED BY EACH       

 REPORTING       9. SOLE DISPOSITIVE POWER

PERSON WITH         1,748,648

                10. SHARED DISPOSITIVE POWER

                    

11. AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON

        1,748,648

12. CHECK BOX IF THE AGGREGATE AMOUNT IN ROW (11)             [ ]
    EXCLUDES CERTAIN SHARES*


13. PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW (11)

        15.0%

14. TYPE OF REPORTING PERSON*

        PN




                             SCHEDULE 13D

CUSIP No.         None                                   Page 5 of 10 Pages

1.  NAME OF REPORTING PERSONS.
  
        CGG INVESTORS LLC

2.  CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP*    (a)  [X]
                                                         (b)  [ ]

3.  SEC USE ONLY


4.  SOURCE OF FUNDS*

        AF

5.  CHECK BOX IF DISCLOSURE OF LEGAL PROCEEDINGS IS 
    REQUIRED PURSUANT TO ITEMS 2(d) or 2(e)                   [ ]


6.  CITIZENSHIP OR PLACE OF ORGANIZATION

        DELAWARE

  NUMBER OF      7. SOLE VOTING POWER

   SHARES           1,748,648

 BENEFICIALLY    8. SHARED VOTING POWER

OWNED BY EACH       

 REPORTING       9. SOLE DISPOSITIVE POWER

PERSON WITH         1,748,648

                10. SHARED DISPOSITIVE POWER

                    

11. AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON

        1,748,648

12. CHECK BOX IF THE AGGREGATE AMOUNT IN ROW (11)             [ ]
    EXCLUDES CERTAIN SHARES*


13. PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW (11)

        15.0%

14. TYPE OF REPORTING PERSON*

        OO





                             SCHEDULE 13D

CUSIP No.         None                                   Page 6 of 10 Pages

1.  NAME OF REPORTING PERSONS.
  
        GF LTD. TRANSACTION PARTNERSHIP, L.P.

2.  CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP*    (a)  [ ]
                                                         (b)  [X]

3.  SEC USE ONLY


4.  SOURCE OF FUNDS*

        AF

5.  CHECK BOX IF DISCLOSURE OF LEGAL PROCEEDINGS IS 
    REQUIRED PURSUANT TO ITEMS 2(d) or 2(e)                   [ ]


6.  CITIZENSHIP OR PLACE OF ORGANIZATION

        DELAWARE

  NUMBER OF      7. SOLE VOTING POWER

   SHARES           28,423

 BENEFICIALLY    8. SHARED VOTING POWER

OWNED BY EACH       0

 REPORTING       9. SOLE DISPOSITIVE POWER

PERSON WITH         28,423

                10. SHARED DISPOSITIVE POWER

                    0

11. AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON

        28,423

12. CHECK BOX IF THE AGGREGATE AMOUNT IN ROW (11)             [ ]
    EXCLUDES CERTAIN SHARES*


13. PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW (11)

        .2%

14. TYPE OF REPORTING PERSON*

        PN




     This Statement on Schedule 13D, relating to the Ordinary Shares of
nominal value two euros each (the "Ordinary Shares") of Compagnie Generale
de Geophysique, a company organized under the laws of the Republic of
France (the "Issuer") amends the Schedule 13D filed on February 4, 2000 by
and on behalf of Energy Fund II GP, LLC, Beacon Energy Investors II, L.P.,
The Beacon Group Energy Investment Fund II, L.P., CGG Investors, LLC, and
GF Ltd. Transaction Partnership, L.P. (collectively, the "Reporting
Persons") and amended by Amendment No. 1 thereto filed on December 13,
2001, Amendment No. 2 thereto filed on October 4, 2004, and Amendment No. 3
thereto filed on March 9, 2005.

ITEM 1.   SECURITY AND ISSUER.

     Unchanged.

ITEM 2.   IDENTITY AND BACKGROUND.

     Unchanged.

ITEM 3.   SOURCE AND AMOUNT OF FUNDS OR OTHER CONSIDERATION.

     Unchanged.

ITEM 4.   PURPOSE OF THE TRANSACTION.

     Item 4 is hereby amended in its entirety as follows:

     On March 9, 2005, the Reporting Persons announced that the Reporting
Persons intend to dispose of some or all of the Ordinary Shares owned by
them and had engaged an investment bank to assist in any such disposition
of Ordinary Shares. Pursuant to a Placement Agency Agreement, dated March
14, 2005 (the "Placement Agreement"), CGG Investors, LLC and GF Ltd.
Transaction Partnership, L.P. (together, the "Sellers"), agreed to sell
1,777,071 Ordinary Shares at a price of (euro)63 per share to a number of
investors in a private placement that is scheduled to close on March 18,
2005. The Sellers will pay the placement agent a commission equal to 3% of
the gross proceeds of any sale of Ordinary Shares that are received by the
Sellers. In addition, an incentive commission of up to a further 1% of the
gross proceeds of any sale of Ordinary Shares by the Sellers may be paid to
the placement agent in the sole discretion of the Sellers.

     The foregoing description of the Placement Agreement is not intended
to be complete and is qualified in it is entirety by the complete text of
the Placement Agreement, all of which is incorporated herein by reference.
The Placement Agreement is filed as Exhibit 9 hereto.

     Except as disclosed in this Item 4, none of the Reporting Persons have
any plans or proposals that relate to or would result in any of the events
described in paragraphs (a) through (j) of Item 4.

ITEM 5.   INTEREST IN SECURITIES OF THE ISSUER.

     Item 5 is hereby amended in its entirety as follows:

     (a) The aggregate number and percentage of the Ordinary Shares
beneficially owned by each of the Reporting Persons are set forth on the
cover pages of this Statement on Schedule 13D, and such information is
incorporated herein by reference. Upon closing of the private placement
described above in Item 4, the Reporting Persons expect to beneficially own
0 Ordinary Shares, representing approximately 0% of the total outstanding
Ordinary shares outstanding.

     (b) The number of Ordinary Shares as to which there is sole power to
vote or to direct the vote, sole power to dispose or to direct the
disposition, or shared power to dispose or direct the disposition for the
Reporting Persons is set forth on the cover pages of this Statement on
Schedule 13D, and such information is incorporated herein by reference.
Pursuant to the transactions described in Item 5(c) below, (i) the
1,777,071 Ordinary Shares beneficially owned by Energy Fund II GP, LLC and
Beacon Energy Investors II, L.P. represent 23.8 percent of the voting
rights of the Issuer; (ii) the 1,748,648 Ordinary Shares beneficially owned
by The Beacon Group Energy Investment Fund II, L.P. and CGG Investors, LLC
represent 23.4 percent of the voting rights of the Issuer; and (iii) the
28,423 Ordinary Shares beneficially owned by GF Ltd. Transaction
Partnership, L.P. represent .4 percent of the voting rights of the Issuer.
Upon closing of the private placement described above in Item 4, none of
the Reporting Persons expect to have the power to vote or the direct the
vote with respect to, or dispose or direct the disposition of, any Ordinary
Shares.

     (c) The Issuer's Articles of Association provide that a double voting
right is allocated to all registered and fully paid-up Ordinary Shares
registered in the name of the same holder for at least two years. Pursuant
to this provision, on December 13, 2001, the Ordinary Shares owned by the
Reporting Persons were allocated double voting rights. Additionally, on
October 7, 2002, the Issuer informed the Reporting Persons that due to the
lack of providing notice to the Issuer within fifteen days of crossing the
16 percent, 18 percent, and 20 percent threshold, the Reporting Persons had
lost a total of 760,742 voting rights. Pursuant to the Issuer's Articles of
Association, because two years have elapsed since the last notification
made by the Reporting Persons on October 4, 2002, the Reporting Persons
have automatically acquired certain double voting rights.

     (d) The investors in The Beacon Group Energy Investment Fund II, L.P.
and GF Ltd. Transaction Partnership, L.P. have the right to receive
dividends from, and the proceeds from the sale of, the respective Ordinary
Shares reported by such persons on the cover pages of this Statement on
Schedule 13D. No such investor has such right with respect to more than 5%
of the Ordinary Shares. Upon the closing of the private placement described
above in Item 4, the investors purchasing shares in the private placement
will have the right to receive dividends from, and the proceeds from the
sale of, their respective Ordinary Shares.

     (e) Not applicable.

ITEM 6.   CONTRACTS, ARRANGEMENTS, UNDERSTANDINGS OR RELATIONSHIPS WITH 
          RESPECT TO SECURITIES OF THE ISSUER.

     Item 6 is hereby amended in its entirety as follows:

     Other than the Subscription Agreement, which was previously filed as
Exhibit 1 to this Statement on Schedule 13D, the Registration Rights
Agreement, which was previously filed as Exhibit 2 to this Statement on
Schedule 13D, and the Placement Agreement described in Item 4 and filed as
Exhibit 9 to this Statement on Schedule 13D, none of the Reporting Persons,
nor, to the best of their knowledge, any of their directors or executive
offices, are parties to any contract, arrangement, understanding or
relationship (legal or otherwise) with respect to any securities of the
Issuer.

ITEM 7.   MATERIAL TO BE FILED AS EXHIBITS.

     Exhibit 8 -- Agreement of Joint Filing

     Exhibit 9 -- Placement Agency Agreement, dated March 14, 2005



                                 SIGNATURE

     After reasonable inquiry and to the best of my knowledge and belief, I
certify that the information set forth in this statement is true, complete
and correct.

Dated:  March 15, 2005

                      ENERGY FUND II GP, LLC

                      By: /s/ John J. MacWilliams
                         ----------------------------------------------
                         Authorized Signatory


                      BEACON ENERGY INVESTORS II, L.P.

                      By:    Energy Fund II GP, LLC

                             By: /s/ John J. MacWilliams
                                ---------------------------------------
                                Authorized Signatory


                      THE BEACON GROUP ENERGY INVESTMENT FUND II, L.P.

                      By:    Beacon Energy Investors II, L.P.
                             By:     Energy Fund II GP, LLC

                                     By: /s/ John J. MacWilliams
                                        -------------------------------
                                        Authorized Signatory


                      CGG INVESTORS, LLC

                      By:    The Beacon Group Energy Investment Fund II, L.P.
                             By:     Beacon Energy Investors II, L.P.
                                     By:    Energy Fund II GP, LLC

                                            By: /s/ John J. MacWilliams
                                               -------------------------
                                               Authorized Signatory


                      GF LTD. TRANSACTION PARTNERSHIP, L.P.

                      By:    Beacon Energy Investors II, L.P.
                             By:     Energy Fund II GP, LLC

                                     By: /s/ John J. MacWilliams
                                        ---------------------------------
                                        Authorized Signatory



                                 SCHEDULE I



                                       STATE OF 
               NAME                    INCORPORATION     BUSINESS ADDRESS
               ----                    -------------     ----------------

                                                   
Energy Fund II GP, LLC                 Delaware          1221 Avenue of the Americas
                                                         New York, New York 10020

Beacon Energy Investors II, L.P.       Delaware          1221 Avenue of the Americas
                                                         New York, New York 10020

The Beacon Group Energy                Delaware          1221 Avenue of the Americas
Investment Fund II, L.P.                                 New York, New York 10020

CGG Investors, LLC                     Delaware          1221 Avenue of the Americas
                                                         New York, New York 10020

GF Ltd. Transaction Partnership, L.P.  Delaware          1221 Avenue of the Americas
                                                         New York, New York 10020




                                 EXHIBIT 8

                         AGREEMENT OF JOINT FILING

The undersigned agree that the foregoing Statement on Schedule 13D is being
filed with the Commission on behalf of each of the undersigned pursuant to
Rule 13d-1(k).

Dated:  March 15, 2005

                      ENERGY FUND II GP, LLC

                      By: /s/ John J. MacWilliams
                         ----------------------------------------------
                         Authorized Signatory


                      BEACON ENERGY INVESTORS II, L.P.

                      By:    Energy Fund II GP, LLC

                             By: /s/ John J. MacWilliams
                                ---------------------------------------
                                Authorized Signatory


                      THE BEACON GROUP ENERGY INVESTMENT FUND II, L.P.

                      By:    Beacon Energy Investors II, L.P.
                             By:     Energy Fund II GP, LLC

                                     By: /s/ John J. MacWilliams
                                        -------------------------------
                                        Authorized Signatory


                      CGG INVESTORS, LLC

                      By:    The Beacon Group Energy Investment Fund II, L.P.
                             By:     Beacon Energy Investors II, L.P.
                                     By:    Energy Fund II GP, LLC

                                            By: /s/ John J. MacWilliams
                                               -------------------------
                                               Authorized Signatory


                      GF LTD. TRANSACTION PARTNERSHIP, L.P.

                      By:    Beacon Energy Investors II, L.P.
                             By:     Energy Fund II GP, LLC

                                     By: /s/ John J. MacWilliams
                                        ---------------------------------
                                        Authorized Signatory



                                 EXHIBIT 9
                         PLACEMENT AGENCY AGREEMENT

                               March 14, 2005

Lehman Brothers International (Europe) ("Lehman Brothers")
25 Bank Street
London E14 5LE
England

Ladies and Gentlemen:

     1. Introduction. CGG Investors, LLC ("CGGI") and GF Ltd. Transaction
Partnership, L.P. ("GFLTP" and, together with CGGI, the "Selling
Shareholders"), each a shareholder of Compagnie Generale de Geophysique
S.A. (the "Company"), a societe anonyme (corporation) organized under the
laws of the Republic of France propose to sell the respective numbers of
shares (collectively, the "Shares") set forth opposite their names in
Schedule A hereto, all such Shares being ordinary shares, (euro)2 par
value, of the Company (the "Ordinary Shares") At a per share price of
(euro)63 pursuant to a private institutional offering (the "Placement") as
further described below. This placement agency agreement (the "Agreement")
provides for the terms on which Lehman Brothers is authorized to act as
sole bookrunning lead manager (the "Placement Agent") for, and will assist
the Selling Shareholders in offering and selling the Shares pursuant to,
the Placement.

     Any sales pursuant to the Placement will be made by the Selling
Shareholders directly to the purchasers of the Shares (the "Investors"),
including to Investors in the United States pursuant to agreements for the
sale of the Shares to be entered into by such Selling Shareholder directly
with an Investor in the form annexed hereto as Exhibit A or such other form
as is mutually satisfactory to the Selling Shareholder and the Placement
Agent (each such agreement, a "Share Sale Agreement).

     The Selling Shareholders understand that the Placement Agent proposes
to make a private offering of the Shares, as soon as the Placement Agent
deems advisable after this Agreement has been executed and delivered, (i)
to persons in the United States whom the Placement Agent reasonably
believes to be qualified institutional buyers ("QIBs") as defined in Rule
144A under the U.S. Securities Act of 1933, as amended (the "Securities
Act") and an accredited investor within the meaning of Regulation D under
the Securities Act, in reliance upon Section 4 of the Securities Act, in
transactions exempt from the registration requirements of the Securities
Act and (ii) to institutional and other investors that are not "U.S.
persons" (as defined in Regulation S) outside the United States in reliance
on Regulation S under the Securities Act, as such regulation may be amended
from time to time ("Regulation S").

     The Selling Shareholders hereby confirm their agreement with the
Placement Agent as follows:

     2.   Representations and Warranties of the Selling Shareholders.
          ----------------------------------------------------------

     (a) Each Selling Shareholder, severally and not jointly with the other
Selling Shareholder, represents and warrants as to itself to, and agrees
for itself with, the Placement Agent that:

               (i) Such Selling Shareholder has and as of the Closing Date
          (as defined in Section 4 below) will have good, valid and
          unencumbered tile to the Shares to be delivered by it on the
          Closing Date, and upon the delivery and payment for the Shares on
          the Closing Date the Investors acquiring such Shares will acquire
          good, valid and unencumbered title to the Shares delivered by
          such Selling Shareholders on the Closing Date.

               (ii) The Shares to be sold by such Selling Shareholder are
          freely transferable by such Selling Shareholder to the Investors
          in the manner contemplated in this Agreement.

               (iii) Such Selling Shareholder has been duly organized, is
          validly existing and, if applicable, is in good standing under
          the laws of its jurisdiction of organization or incorporation.

               (iv) Such Selling Shareholder has full right, power and
          authority (i) to enter into this Agreement and any Share Sale
          Agreement entered into by such Selling Shareholder, (ii) to sell,
          assign, transfer and deliver the Shares to be delivered by it and
          (iii) to perform its obligations under this Agreement and any
          such Share Sale Agreement.

               (v) Each of this Agreement and any Share Sale Agreement
          entered into by such Selling Shareholder has been duly authorized
          by such Selling Shareholder and this Agreement and any such Share
          Sale Agreement constitute valid and binding obligations of such
          Selling Shareholder enforceable against it in accordance with
          their terms, except as rights of indemnification may be limited
          by means of public policy.

               (vi) The execution and delivery of this Agreement and any
          Share Sale Agreement entered into by such Selling Shareholder,
          the performance by the Selling Shareholder of its obligations
          hereunder and thereunder, the consummation of the transactions
          contemplated hereby and thereby and the sale, transfer and
          delivery of the Shares to be sold by such Selling Shareholder
          hereunder and thereunder will not result in a breach or violation
          of any of the terms and provisions of, or constitute a default
          under (A) any statute, rule, regulation or order of any
          governmental agency or of any court, domestic or foreign, having
          jurisdiction over such Selling Shareholder or any of its
          properties, or (B) any contract, agreement or instrument to which
          such Selling Shareholder is a party or by which such Selling
          Shareholder is bound or to which any of its properties is
          subject, or (C) the certificate of incorporation or formation,
          by-laws or other organizational documents of such Selling
          Shareholder, and no consent, approval, authorization or order of
          or qualification with any governmental agency is required for the
          performance by such Selling Shareholder of its obligations under
          this Agreement or any Share Sale Agreement or the consummation of
          the transactions contemplated hereby or thereby, except in the
          cases of (A) and (B) above for such breaches, defaults or
          violations that would not reasonably be expected to result in a
          material adverse effect on the condition (financial or other) or
          on the business, properties or results of operations of the
          Company.

               (vii) Such Selling Shareholder has not entered into and will
          not enter into any contractual arrangement with respect to the
          distribution of the Shares except for this Agreement and any
          Share Sale Agreement.

     (b) Each of the Selling Shareholders, jointly and severally,
represents and warrants to, and agrees with, the Placement Agent that:

               (i) To the knowledge of the Selling Shareholder, it does not
          have any "information privilegiee" (as defined in Article 621-1
          of the Reglement General de l'Autorite des Marches Financiers)
          with respect to the Company or its subsidiaries. As used in this
          Agreement, "knowledge of a Selling Shareholder" shall mean the
          actual knowledge of any partner, principal or manager of such
          Selling Shareholder who is responsible for monitoring the Selling
          Shareholder's investment in the Company.

               (ii) There are no legal or governmental proceedings or
          investigations pending or, to the knowledge of such Selling
          Shareholder and its affiliates, threatened that would have a
          material adverse effect on the power or ability of the Selling
          Shareholder to perform its obligations under this Agreement or
          any Share Sale Agreement or to consummate the transactions
          contemplated hereby and thereby.

               (iii) No transfer, stamp, issue, registration, documentary
          or other similar taxes and duties, including interest and
          penalties, are payable under the laws of France, the United
          States or any political subdivision thereof in connection with
          the execution and delivery of this Agreement or the sale and
          delivery of the Shares.

               (iv) Neither such Selling Shareholder, its affiliates, nor
          any person acting on their behalf (A) has engaged, or will
          engage, in any form of general solicitation or general
          advertising (within the meaning of Rule 502(c) Regulation D under
          the Securities Act) in connection with the offer or sale of the
          Shares in the United States, or (B) has engaged, or will engage,
          in any "directed selling efforts" (within the meaning of Rule
          902(c) of Regulation S) with respect to the Shares.

               (v) Neither such Selling Shareholder nor any of is
          affiliates has taken, directly or indirectly, any action which
          was designed to or which has constituted or which might
          reasonably be expected to cause or result in stabilization or
          manipulation of the price of any security of the Company or taken
          any action to facilitate the sale or resale of the Shares.

               (vi) Neither such Selling Shareholder nor any of its
          directors, officers, affiliates or direct or indirect controlling
          persons has issued or will issue, directly or indirectly, without
          the prior consent of the Placement Agent, any communication, and
          none of them has taken or omitted to take or will take or omit to
          take any other action, which may adversely affect the ability the
          Placement Agent, or any of its affiliates acting as stabilizing
          manager, to undertake stabilizing action in accordance with
          applicable law or regulations or the rules of any competent
          authority, including without limitation the Financial Services
          Authority.

     3. Placement of the Shares by the Placement Agent. The Selling
Shareholders understand that the Placement Agent will be acting as the
agent of the Selling Shareholders in the offering and sale of the Shares
and agree that, in connection therewith, the Placement Agent will use is
"best efforts" to place the Shares. This Agreement shall not give rise to
any express or implied commitment by the Placement Agent to purchase or
place any of the Shares.

     4. Delivery of the Shares. Delivery of the Shares to the Investors
identified by the Placement Agent hereunder shall be made for value on
March 18, 2005, or at such later date (which shall be a business day) or
place as shall be determined by agreement between the Placement Agent and
the Selling Shareholders. The foregoing date and time for delivery of the
Shares are sometimes referred to herein as the "Closing Date". On the
Closing Date, the Selling Shareholders shall deliver or cause to be
delivered the Shares to such account or accounts held by Investors as the
Placement Agent shall notify to the Selling Shareholders, and the Placement
Agent shall cause to be delivered, by wire transfer(s) or cashiers
check(s), the purchase price for such Shares to such accounts of the
Selling Shareholders as the Selling Shareholders shall specify. Time shall
be of the essence, and delivery at the time and places specified pursuant
to this Agreement are further conditions (in addition to those set out in
paragraph 7 below) to the obligations of the Placement Agent and the
Selling Shareholders hereunder.

     5. Representations of the Placement Agent. The Placement Agent
represents and warrants to the Selling Shareholders that:

     (a) It has full right, power and authority to enter into this
Agreement and to perform its obligations hereunder.

     (b) Neither it nor its affiliates nor any person acting on its or
their behalf has offered or placed, and no such person will offer or place,
any Shares except (i) to those persons that it reasonably believes to be
QIBs and an accredited investor within the meaning of Regulation D under
the Securities Act or (ii) in accordance with Regulation S, and in all
cases has taken reasonable steps to ensure that each Investor or its duly
authorized agent has made the representations contained in notice set forth
in Exhibit B.

     (c) Neither it nor any of its affiliates nor any person acting on its
or their behalf has made or will make offers or placements of the Shares in
the United States by means of any form of general solicitation or general
advertising (within the meaning of Rule 502(c) of Regulation D under the
Securities Act) or any "directed selling efforts" (within the meaning of
Rule 902(c) of Regulation S) in the United States with respect to the
Shares.

     (d) It will perform its duties hereunder in connection with the
Placement according to customary professional standards for similar
offerings.

     6. Certain Agreements of the Selling Shareholders. The Selling
Shareholders, jointly and severally, agree with the Placement Agent that:

     (a) If, at any time prior to the completion of the Placement, such
Selling Shareholder has or acquires knowledge of any information
privilegiee (as described in Section 2 (g)) with respect to the Company or
its subsidiaries, such Selling Shareholder promptly will notify the
Placement Agent of such event.

     (b) Before the completion of the Placement, such Selling Shareholder
and its affiliates will not, and will not permit any person acting on its
or their behalf to, engage in any form of general solicitation or
advertising (within the meaning of Rule 502(c) of Regulation D under the
Securities Act) in connection with any offer or sale of the Shares in the
United States.

     (c) Before the completion of the Placement, such Selling Shareholder
and its affiliates will not, and will not permit any person acting on its
or their behalf to, engage in any directed selling efforts in the United
States with respect to the Shares to be sold outside the United States, and
will ensure that they comply and any person acting on their behalf (other
than a Placement Agent for this offering of the Shares) complies with any
applicable offering restrictions of Regulation S with respect to such
Shares.

     (d) In connection with the Placement, until the Placement Agent shall
agree that the completion of the Placement has occurred, neither such
Selling Shareholder nor any of its affiliates has or will, either alone or
with one or more other persons, bid for or purchase for any account in
which it or any of its affiliates has a beneficial interest in any Ordinary
Shares or attempt to induce any person to purchase any Shares; and neither
it nor any of its affiliates will make bids or purchases for the purpose of
creating actual, or apparent, active trading in, or of raising the price
of, the Ordinary Shares.

     (e) The Selling Shareholders will not designate any other placement
agent or manager without the prior consent of the Placement Agent such
consent not to be unreasonably withheld.

     7. Conditions to the Obligations of the Placement Agent. The
facilitation of the Placement of any of the Shares by the Placement Agent
will be subject to the accuracy of the representations and warranties on
the part of the Selling Shareholders herein, to the accuracy of the
statements of officers of the Selling Shareholders made pursuant to the
provisions hereof, to the performance by the Selling Shareholders of their
respective obligations hereunder and to the following additional conditions
precedent:

     (a) Subsequent to the execution and delivery of this Agreement, there
shall not have occurred (i) any change, or any development or event
involving a prospective change, in the condition (financial or other),
business, properties or results of operations of the Company which, in the
reasonable judgment of the Placement Agent, is material and adverse and
makes it impractical or inadvisable to proceed with completion of the
Placement or the sale of and payment for the Shares; (ii) any change in
U.S., French, or international financial, political or economic conditions
or currency exchange rates or exchange controls as would, in the reasonable
judgment of the Placement Agent, after consultation with the Selling
Shareholders, be likely to prejudice materially the market for the Shares
or dealings in the Shares in the secondary market, (iii) any material
suspension or material limitation of trading in securities generally on
Euronext Paris or the New York Stock Exchange, or any setting of minimum
prices for trading on either such exchange; (iv) any suspension of trading
of any securities of the Company on either such exchange; (v) any banking
moratorium declared by U.S. Federal, New York state or French authorities;
(vi) any major disruption of settlements of securities or clearance
services in the United States or France or (vii) any attack on, outbreak or
escalation of hostilities or act of terrorism involving the United States
or France, any declaration of war by Congress or any other national or
international calamity or emergency if, in the judgment of the Placement
Agent, the effect of any such attack, outbreak, escalation, act,
declaration, calamity or emergency makes it impractical or inadvisable to
proceed with completion of the Placement or sale of and payment for the
Shares.

     (b) The Placement Agent shall have received an opinion, dated the
Closing Date, of Debevoise & Plimpton LLP, special counsel to the Placement
Agent, in form and substance satisfactory to the Placement Agent.

     (c) The Placement Agent shall have received an opinion, dated the
Closing Date, of Fried, Frank, Harris, Shriver & Jacobson LLP, counsel to
the Selling Shareholders, in form and substance satisfactory to the
Placement Agent in the form annexed hereto as Exhibit C.

     (d) The Placement Agent shall have received the extract of the minutes
of March 7, 2005 annexed hereto as Exhibit D, which extract shall have been
certified by the Secretaire Generale of the Company as being a true and
correct extract of the foregoing minutes.

     The Placement Agent may in its sole discretion waive compliance with
any conditions to its obligations hereunder.

     8. Placement Agent's Commission. (a) As compensation for its services
hereunder, the Placement Agent shall be entitled to a commission equal to
3% of the gross proceeds of any sale of Shares received by the Selling
Shareholders in the Placement. Such commission shall be due and payable in
US dollars on the Closing Date. Such commission shall be paid by each
Selling Shareholders proportionally in respect of the number of shares sold
by each of them in the Placement. For the avoidance of doubt, each Selling
Shareholder's liability under this paragraph 8 shall be several, not joint.
In addition, an incentive commission of up to a further 1% of the gross
proceeds of any sale of Shares by the Selling Shareholders in the Placement
may be payable on the Closing Date at the sole discretion of the Selling
Shareholders. On the Closing Date, the Selling Shareholders shall pay or
cause to be paid such commissions to the Placement Agent by instructing the
Placement Agent to deduct such commissions from the gross proceeds of the
sales of Shares paid to the Selling Shareholders pursuant to paragraph 4
hereof.

     (b) In addition to the commissions set forth above, the Selling
Shareholders shall reimburse the Placement Agent for its reasonable
out-of-pocket expenses incurred in connection with the Placement up to a
maximum of (euro)75,000; provided however, that in the event the Selling
Shareholders pay the incentive commission referred to above, they shall
have no obligation to reimburse the expenses of the Placement Agent
hereunder. Such reimbursed expenses will include, without limitation, all
expenses and disbursements (including legal fees, travel, accommodation and
document production) . All other expenses shall be borne directly by the
Selling Shareholders; for the avoidance of doubt, such direct expenses
shall include, without limitation, (i) the costs incurred by the Selling
Shareholders (such as costs incurred in retaining their own legal or other
advisers or auditors) and (ii) any expenses associated with preparing and
filing documentation with appropriate authorities (if any) and any costs or
expenses associated with the road shows, which shall be paid directly by
the Selling Shareholders. The Placement Agent shall discuss in advance with
the Selling Shareholders any actions or decisions that may entail
significant expenses to be borne by the Selling Shareholders and shall
obtain the prior approval of the Selling Shareholders therefor, such
approval not to be unreasonably withheld or delayed. For the avoidance of
doubt, the expenses referred to herein shall be payable whether or not the
Placement is consummated.

     (c) All commissions, expenses and other payments (including
indemnification pursuant to paragraph 9) provided for under this Agreement
are exclusive of any Value Added Tax payable thereon and shall be made
without withholding or deduction for or on account of any present or future
taxes, duties or governmental charges whatsoever unless a Selling
Shareholder is compelled by law to deduct or withhold such taxes, duties or
charges. In that event, such Selling Shareholder shall pay such additional
amounts as may be necessary in order that the net amounts received after
such withholding or deduction shall equal the amounts that would have been
received if no withholding or deduction had been made.

     9. Indemnification. (a) (i) The Selling Shareholders, jointly and
severally, agree to indemnify and hold harmless the Placement Agent and its
affiliates, each other person (if any) controlling the Placement Agent or
any of its affiliates, and the directors, officers, agents and employees of
each of the foregoing (for the purposes of this paragraph, each a "Lehman
Indemnified Person"), from and against any and all losses, claims, damages
or liabilities (including, without limitation, losses, claims, damages or
liabilities relating to taxes), or, in each case, actions in respect
thereof (each of the foregoing a "Loss", and collectively "Losses"), to the
extent that they relate to or arise out of or in connection with any breach
of any of the representations, warranties and covenants of such Selling
Shareholder contained in the Placement Agency Agreement; provided, however,
with respect to Losses relating to inaccuracies of the representations
contained in Section 2(a), no Lehman Indemnified Person shall have the
right to seek indemnification from the non-breaching Selling Shareholder
unless and until the breaching Selling Shareholder shall have failed to
fulfill its indemnification obligations hereunder (as a result of its
dissolution, insolvency, default under this Agreement or otherwise); and
provided further that the foregoing indemnification will not, as to any
Lehman Indemnified Person, apply to Losses to the extent that they are
determined by a court of competent jurisdiction to have resulted from the
negligence or willful misconduct of such Lehman Indemnified Person and the
Selling Shareholders will reimburse the Placement Agent for any legal or
other expenses (including fees and expenses of attorneys) reasonably
incurred by the Placement Agent in connection with investigating or
defending any such action or claim as such expenses are incurred.

     (ii) The benefit of this paragraph 9 shall be extended to each Lehman
Indemnified Person as if this paragraph were separately repeated in
relation to each of them and they were severally named in this Agreement.
Each Lehman Indemnified Person will have the right to enforce directly its
rights against the Selling Shareholder under this paragraph 9; provided
that no Lehman Indemnified Person (save for Lehman Brothers) may enforce
such rights against the Selling Shareholder without first offering Lehman
Brothers the opportunity to have sole conduct, on behalf of the relevant
Lehman Indemnified Person, of any action, giving rise to such
indemnification. If Lehman Brothers elects to have sole conduct of any such
action on behalf of any Lehman Indemnified Person, Lehman Brothers may
settle and/or terminate such action and/or waive any entitlement thereto
with the prior written consent of the Selling Shareholders (such consent
not to be unreasonably withheld). Lehman Brothers shall not have any
responsibility to any of the Lehman Indemnified Persons under or as a
result of this paragraph 9.

     (iii) The obligations of the Selling Shareholders under this paragraph
9 shall be in addition to any liability that the Selling Shareholders may
otherwise have.

     (b) The Placement Agent agrees to indemnify and hold harmless the
Selling Shareholders and the directors, officers, agents and employees of
the Selling Shareholders from and against any and all Losses to the extent
that they relate to or arise out of or in connection with any breach of, or
inaccuracy in, any of the representations and warranties contained in
paragraph 5; provided, however, that the foregoing indemnification will
not, as to the Selling Shareholders, apply to Losses to the extent that
they are determined by a court of competent jurisdiction to have resulted
from the gross negligence or willful misconduct of the Selling
Shareholders; and the Placement Agent will reimburse the Selling
Shareholders for any legal or other expenses (including reasonable fees and
expenses of attorneys) reasonably incurred by the Selling Shareholders in
connection with investigating or defending any such action or claim as such
expenses are incurred.

     (c) (i) For the purposes of this paragraph c, the party seeking
indemnification shall be known as the "Indemnified Party" and the party
from whom indemnification is sought shall be known as the "Indemnifying
Party".

     (ii) As promptly as practicable after receipt by an indemnified Party
of notice of any Loss in respect of which an Indemnifying Party may be
liable under this paragraph 6, the Indemnified Party shall give notice
thereof (the "Indemnification Notice") to the Indemnifying Party. The
failure of any Indemnified Party to give such notice shall not relieve the
Indemnifying Party of its indemnification obligations under this paragraph
9, except to the extent such failure results in a lack of actual notice to
the Indemnifying Party and the Indemnifying Party is materially prejudiced
as a result of failure to receive such notice.

     (iii) In the case of any claim asserted by a third party, the
Indemnified Party shall permit the Indemnifying Party, within 15 days of
the Indemnification Notice, at its option and expense, to take over and
assume the defense of any such claim by counsel satisfactory to the
Indemnified Party and to settle or otherwise dispose of the same; provided
that if the Indemnifying Party does so take over and assume the defense,
(x) the Indemnified Party may at its discretion at all times participate,
at its own expense, in such defense by counsel of its own choice, and (y)
the Indemnifying Party shall, at all times and to the maximum extent
possible, keep the Indemnified Party informed of the status of such claim
and the proceedings related thereto. The Indemnifying Party shall not, in
defense of any such claim, except with the prior written consent of the
Indemnified Party, enter into any settlement that does not include, as an
unconditional term thereof, the giving by the claimant or plaintiff in
question to the Indemnified Party and its affiliates a release of all
liabilities in respect of such claims.

     (d) For the avoidance of doubt, it is expressly understood and agreed
that the Lehman Indemnified Persons do not assume any obligation duty or
liability in contract, tort or otherwise beyond that of a duty to exercise
reasonable care and skill, and in no circumstances shall Lehman Brothers,
its affiliates, directors, officers or employees or advisors be liable in
contract, tort or otherwise for loss (whether direct or indirect) of
profits, business or anticipated savings or for any indirect or
consequential loss whatsoever.

     10. Scope of the Placement Agent's Responsibilities. The Selling
Shareholders recognize that, in providing services under this Agreement,
the Placement Agent will rely upon and assume the accuracy and completeness
of the financial, accounting, tax and other information discussed with or
reviewed by it for such purpose, and the Placement Agent does not assume
responsibility for the accuracy and completeness thereof. The Placement
Agent will have no obligation to conduct any independent evaluation or
appraisal of the assets or the liabilities of the Company or any other
party or to advise or opine on related solvency issues. It is understood
and agreed that the Placement Agent will act under this Agreement as an
independent contractor with duties solely to the Selling Shareholders and
nothing in this Agreement or the nature of the services to be provided
hereunder shall be deemed to create a fiduciary or agency relationship
between the Placement Agent and the Selling Shareholders

     11. FSA Matters. (a) Lehman Brothers and members of the Lehman
Brothers group of companies are engaged in a wide range of investment
business, both for their own account and for clients. This may give rise to
situations where Lehman Brothers and/or any division or department of
Lehman Brothers or its affiliates or related companies may have interests
which conflict with those of the Selling Shareholders or the Company or may
be regarded as having interests which conflict with the interests of the
Selling Shareholders or the Company or any of them may represent clients
whose interests may conflict with the interests of the Selling Shareholders
or the Company in relation to the Placement or have some other interest,
relationship or arrangement that is material in the context of the
Placement ("Material Interest").

     (b) In accordance with the rules of the Financial Services Authority
(the "FSA Rules"), Lehman Brothers has established practices and procedures
designed to ensure the independence of advice. These include setting up
so-called "Chinese Walls" which involve restricting employees' access to
information relating to clients with whom they are not directly concerned
and requiring employees to disregard Material Interests if they arise.

     (c) The Selling Shareholders hereby acknowledge and accept, so as
expressly to override any duties, obligations or restrictions which would
otherwise be implied by law or by the FSA Rules, that Lehman Brothers or
any member of the Lehman Brothers group of companies may have Material
Interests and that any particular employees responsible for handling the
Selling Shareholders' affairs may be doing so despite the existence of
Material Interests.

     (d) Each Selling Shareholder hereby acknowledges and accepts that, by
reason of law or duties of confidentiality owed to other persons or the FSA
Rules and/or requirements to maintain Chinese Walls, Lehman Brothers may be
forbidden, or it may be inappropriate for Lehman Brothers, to use or
disclose information to the Selling Shareholders, in particular about
Material Interests.

     (e) Each Selling Shareholder also agrees that (i) Lehman Brothers and
the employees responsible for the Selling Shareholders' affairs are to
provide services to the Selling Shareholders under this letter agreement on
the basis of the information available to them and (ii) in providing those
services, neither Lehman Brothers nor those employees will be required to
consider any information known to Lehman Brothers or any member of the
Lehman Brothers group of companies which is a Material Interest.

     12. Power of Attorney. (a) Each Selling Shareholder hereby irrevocably
constitutes and appoints Lehman Brothers, as its true and lawful
attorney-in-fact (the "Attorney-in-Fact"), with full power and authority,
in the name, place and stead and on behalf of the undersigned, to execute
and deliver any Share Sale Agreement on behalf of the undersigned in the
form annexed hereto as Exhibit A, provided that the per share price shall
be (euro)63 and the aggregate number of Shares pursuant to all such Share
Sale Agreements shall not exceed 1,777,071.

     (b) It is understood that, except as set forth below, the
Attorney-in-Fact, in its capacity as such, assumes no responsibility or
liability to any person. The Attorney-in-Fact, acting in its capacity as
such, shall not be liable for any error of judgment or for any act done or
omitted or for any mistake of fact or law. No implied duties or obligations
shall be read into this Power of Attorney against the Attorney-in-Fact.
This paragraph 12(b) shall in no way affect any other liability, duties or
obligations Lehman Brothers may have acting in any other capacity under
this Agreement.

     13. Survival of Certain Representations and Obligations. The
respective indemnities, agreements, representations, warranties and other
statements of the Selling Shareholders or their officers and of the
Placement Agent set forth in or made pursuant to this Agreement will remain
in full force and effect, regardless of any investigation, or statement as
to the results thereof, made by or on behalf of the Placement Agent or the
Selling Shareholders or any of their respective representatives, officers
or directors or any controlling person, and will survive placement and
delivery of and payment for the Shares. If the Placement is not consummated
for any reason other than the occurrence of any event specified in clauses
(i) through (vii) of paragraph 7(a), the Placement Agent shall be entitled
to its full commission pursuant to the first sentence of paragraph 8(a) of
this Agreement in the event that at any time prior to the expiration of a
three-month period following such termination the Selling Shareholders
complete a financing transaction on terms similar to the terms of the
Placement. The Selling Shareholder shall have the obligation to offer the
Placement Agent the right to act in the capacities specified herein for a
period of three months from the date of such termination.

     14. Notices. All communications hereunder will be in writing and
delivered as follows:

               If to CGGI:

               CGG Investors, LLC
               c/o Beacon Energy Investors II, L.P.
               1221 Avenue of the Americas
               New York, NY 10020
               USA
               Facsimile:  +1 917 464 8307
               Attn:  John J. MacWilliams

               If to GFLTP:

               GF Ltd. Transaction Partnership, L.P.
               c/o Beacon Energy Investors II, L.P.
               1221 Avenue of the Americas
               New York, NY 10020
               USA
               Facsimile: +1 917 464 8307
               Attn:  John J. MacWilliams

               If to the Placement Agent to:

               Lehman Brothers International (Europe)
               25 Bank Street
               London E14 5LE
               England
               Facsimile: To be provided upon request
               Attn:  Head of Legal

     Any notice or other communication hereunder shall be deemed to have
been duly given or served on another party if delivered in person or sent
by first class post, recognized overnight courier service or to the address
of such other party as set forth above or transmitted by fax (with
confirmation thereof) to the facsimile number set forth above. In the case
of posting as aforesaid any such notice shall be deemed to have been
received 48 hours after posting. In the case of sending by overnight
courier as aforesaid any such notice shall be deemed to have been received
the day after sending. In the case of sending by fax as aforesaid any such
notice shall be deemed to have been received upon transmission.

     15. Miscellaneous. This Agreement shall not be assignable by any party
hereto without the prior written consent of the other parties hereto (and
any purported assignment without such consent shall be null and void), is
intended to be solely for the benefit of the parties hereto and is not
intended to confer any benefits upon, or create any rights in favor of, any
person other than the parties hereto except as provided for with respect to
Indemnified Persons in paragraph 9 above. This Agreement may not be amended
or waived except by an instrument in writing signed by each of the parties
hereto. The Agreement may be executed in one or more counterparts and, if
executed in more than one or more counterparts, the executed counterparts
shall each be deemed to be an original but all such counterparts shall
together constitute one and the same instrument. Delivery of an executed
signature page of this Agreement by facsimile transmission shall be
effective as delivery of a manually executed counterpart hereof. This
Agreement supersedes any prior agreement, express or implied, between the
parties hereto with respect to the subject matter hereof and sets forth the
entire understanding of the parties with respect to the Shares.

     16. Disclosures; Confidentiality. (a) The Placement Agent shall have
the right to approve (i) every form of letter, circular, notice or other
written communication (the "Offering Information") from the Selling
Shareholders or any other person acting on their behalf to any offeree or
Investor in connection with the offer and sale of the Shares and (b) the
persons to whom the Selling Shareholders send any such Offering
Information.

     (b) Prior to the Closing Date, except as may be required by applicable
law or regulations, the transactions contemplated by this Agreement may not
publicly be disclosed to any third party or otherwise publicly referred to
by the Selling Shareholders without the prior written consent of the
Placement Agent, it being agreed that the Selling Shareholders may disclose
this Agreement and file such Agreement with the SEC on a Schedule 13D
promptly after execution thereof. Without prejudice to the foregoing, each
Selling Shareholder agrees not to make any notification to the Company
prior to the Closing Date in relation to such Selling Shareholder's
interests in the Company's share capital without the prior consent of the
Placement Agent.

     17. GOVERNING LAW. THIS AGREEMENT SHALL BE GOVERNED BY, AND CONSTRUED
IN ACCORDANCE WITH, THE LAWS OF ENGLAND WITHOUT REGARD TO PRINCIPLES OF
CONFLICTS OF LAWS. THE PARTIES HEREBY SUBMIT TO THE NON-EXCLUSIVE
JURISDICTION OF THE COURTS IN LONDON IN THE UK IN RELATION TO ANY DISPUTE
ARISING OUT OF OR IN CONNECTION WITH THE LETTER.

If the foregoing is in accordance with your understanding of our agreement,
kindly sign and return to us one of the counterparts hereof, whereupon it
will become a binding agreement between the Selling Shareholders and the
Placement Agent in accordance with its terms.



Yours faithfully,

CGG INVESTORS, LLC

   By:   The Beacon Group Energy Investment Fund II, L.P., its sole member
   By:   Beacon Energy Investors II, L.P., its general partner
   By:   Energy Fund II GP, LLC, its general partner
   By:   Beacon Funds Holdings LLC, its sole member
   By:   The Beacon Group, LP, its sole member


   By:   /s/ John J. MacWilliams   
         --------------------------
   Name:  John J. MacWilliams
   Title: General Partner


GF LTD. TRANSACTION PARTNERSHIP, L.P.

   By:   Beacon Energy Investors II, L.P., its general partner
   By:   Energy Fund II GP, LLC, its general partner
   By:   Beacon Funds Holdings LLC, its sole member
   By:   The Beacon Group, LP, its sole member


   By:   /s/ John J. MacWilliams   
         ---------------------------
   Name:  John J. MacWilliams
   Title: General Partner


THE FOREGOING IS HEREBY CONFIRMED AND ACCEPTED
AS OF THE DATE FIRST ABOVE WRITTEN.

LEHMAN BROTHERS INTERNATIONAL (EUROPE)


By:   /s/ David Douglas                     
     -------------------------------
     Name:  David Douglas
     Title: Managing Director



                                                                 SCHEDULE A

                      SHARES INCLUDED IN THE PLACEMENT

--------------------------------- ----------------------------------------
SELLING SHAREHOLDER                            NUMBER OF SHARES
--------------------------------- ----------------------------------------
CGGI                                             1,748,648
--------------------------------- ----------------------------------------
GFLTP                                               28,423
--------------------------------- ----------------------------------------



                                                                  EXHIBIT A

                        FORM OF SHARE SALE AGREEMENT

                                                              March o, 2005

CGG Investors, LLC ("CGGI")
c/o Beacon Energy Investors II, LP
1221 Avenue of the Americas
New York, NY 10020
USA

GF Ltd. Transaction Partnership, L.P. ("GFLTP")
c/o Beacon Energy Investors II, LP
1221 Avenue of the Americas
New York, NY 10020
USA

(CGGI and GFLTP together the "Selling Shareholders")

Lehman Brothers International (Europe)
25 Bank Street
London E14 5LE
England

(for the purposes only of the "Representations" contained herein)

Ladies and Gentlemen:

     In connection with the proposed sale to us of o ordinary shares (the
"Shares") of Compagnie Generale de Geophysique (the "Company"), we confirm
that:

A. REPRESENTATIONS

     1. This certification and agreement is furnished in connection with
our acquisition of the Shares in a private placement facilitated by Lehman
Brothers International (Europe) ("Lehman Brothers") or its affiliates.

     2. We qualify as an accredited investor within the meaning of
Regulation D (an "accredited investor") under the U.S. Securities Act of
1933, as amended (the "Securities Act") and as a "qualified institutional
buyer" within the meaning of Rule 144A under the Securities Act.

     3. We have such knowledge and experience in financial and business
matters to be capable of evaluating the merits and risks of our investment
in the Shares, and we and any accounts for which we are acting are each
able to bear the economic risk of our or their investment.

     4. We have received and have access through our own resources to such
information as we deem necessary or appropriate in order to make our
investment decision. We have conducted our own investigation of the Shares
and the Company and acknowledge that we have not relied on the Company, the
Selling Shareholders, Lehman Brothers or any of their respective affiliates
or any person acting on their behalf with respect to our decision to invest
in the Shares and the Company, and none of such persons has made any
representation to us, express or implied, with respect to the Shares or the
Company.

     5. We will not hold the Selling Shareholders, Lehman Brothers, any of
their respective affiliates or any persons acting on their behalf liable
for any misstatements in or omissions from publicly available information
about the Shares or the Company.

     6. We will comply with all applicable laws and regulations in each
jurisdiction in which we are or may be subject to any securities laws, in
all cases at our own expense.

     7. We understand that the offer and sale to us of the Shares have not
been registered under the Securities Act and that such offer and sale are
being made to us in reliance on an exemption from the registration
requirements of the Securities Act.

     8. We understand that the Shares purchased by us in this offer and
sale are "restricted securities'" as defined in Rule 144(a)(3) under the
Securities Act and as such are not fungible with any other issued and
outstanding ordinary shares or American Depositary Shares of the Company.
Accordingly, we agree that for so long as the Shares purchased by us in
this offer and sale are restricted securities, we will not deposit such
Shares in any depositary receipt facility established or maintained by a
depositary bank including, in particular, the Company's unrestricted
American Depositary Receipt facility.

     9. We agree that, for so long as the Shares purchased by us in this
offer and sale are restricted securities, we will not offer, sell, pledge
or otherwise transfer such Shares except (a) to the Company or any of its
subsidiaries, (b) to a person whom it reasonably believes is a qualified
institutional buyer within the meaning of Rule 144A under the Securities
Act and an accredited investor within the meaning of Regulation D in a
transaction not required to be registered under the Securities Act, (c) in
an offshore transaction effected on Euronext Paris S.A. in accordance with
Rule 903 or Rule 904 of Regulation S under the Securities Act (and not in a
pre-arranged transaction resulting in the resale of such Shares into the
United States), or (d) in accordance with Rule 144 under the Securities Act
(if available), in each case in accordance with any applicable securities
laws of any state of the United States.

     10. We understand that the Shares are not eligible for resale by us
under Rule 144A.

     11. We agree that in the case of any offer, sale, pledge or other
transfer of any Shares purchased by us in this offer and sale made pursuant
to the preceding clauses, the validity of such transaction shall be subject
to the transferee agreeing to be bound by the terms and conditions hereof.

     12. We agree that in the case of any offer, sale, pledge or other
transfer pursuant to clause 9 of any Shares purchased by us in this offer
and sale, the transferor shall be required to provide prompt written
certification thereof to any designee of the Selling Shareholders setting
forth (a) the name and address of the transferee and (b) as applicable, the
specific exception on which basis such transfer is made.

     13. We are acquiring Shares for our own account or for one or more
accounts (each of which is a QIB which is an accredited investor) as to
each of which we exercise sole investment discretion and for each of which
we have full power to make the foregoing acknowledgements, representations
and agreements on behalf of each such account.

     14. We are not acquiring the Shares with a view to distribution
thereof or with any present intention of offering or selling any Shares,
provided that the disposition of our property and property of any accounts
for which we are acting as fiduciary will remain at all times within our
control.

     15. We acknowledge that we shall pay all stamp duty, stamp duty
reserve tax, issue, registration, transfer or other taxes or duties
(including any applicable interest and penalties thereon) payable on or in
connection with the sale and delivery of the Shares purchased by us.

     16. We covenant that the foregoing representations, warranties and
covenants will be true and accurate as of, and acknowledge that such
representations, warranties and covenants shall survive, the date of the
acceptance thereof.

     17. We recognize that the Selling Shareholders and Lehman Brothers
will rely upon the truth and accuracy of the foregoing investment
representations and agreements. We agree that if any of the representations
or warranties made by us herein are no longer accurate, we shall promptly
notify the Selling Shareholders and Lehman Brothers. This letter is
governed by the laws of the State of New York.

B. PURCHASE AND DELIVERY OF AND PAYMENT FOR SHARES

               1. We shall purchase the Shares at (euro)63 per share on the
     date hereof and shall pay the purchase price for the Shares by wire
     transfer or cashiers check to such account or accounts as Lehman
     Brothers shall specify.

               2. The Selling Shareholders agree to deliver, or cause
     Lehman Brothers to deliver, the Shares on the date hereof to such
     account or accounts as we shall specify.

     The Selling Shareholders and Lehman Brothers are entitled to rely upon
this letter agreement and are irrevocably authorized to produce this letter
agreement or a copy hereof to any interested party in any administrative or
legal proceedings or official inquiry with respect to the matters covered
hereby.

                                       Very truly yours,



                                       By:
                                          ----------------------------
                                       Name:
                                       Title:
                                       Name of Purchaser:



THE FOREGOING IS HEREBY CONFIRMED AND ACCEPTED
AS OF THE DATE FIRST ABOVE WRITTEN.

CGG INVESTORS, LLC

     ---------------------------------------
     By Lehman Brothers International (Europe), under power of attorney

GF LTD. TRANSACTION PARTNERSHIP, L.P.

     ---------------------------------------
     By Lehman Brothers International (Europe), under power of attorney



                                                                  EXHIBIT B

           The following text is to be inserted in the invitation
                        telex to non-U.S. Persons.

                        NOTICE TO NON-U.S. INVESTORS

     BECAUSE THE FOLLOWING RESTRICTIONS WILL APPLY, INVESTORS ARE ADVISED
TO CONSULT LEGAL COUNSEL PRIOR TO MAKING ANY OFFER, RESALE, PLEDGE OR
TRANSFER OF ANY OF THE SHARES.

     Reference is made to the proposed offer and sale by CGG Investors, LLC
and GF Ltd. Transaction Partnership, L.P. (the "Selling Shareholders") of
shares of Compagnie Generale de Geophysique (the "Company"), which offer
and sale are being facilitated by Lehman Brothers International (Europe)
("Lehman Brothers") as placement agent.

     Each purchaser of shares (the "Purchaser"), by its acceptance thereof,
will be deemed to have acknowledged, represented to and agreed with the
Selling Shareholders and Lehman Brothers as follows:

          1. The Purchaser is not a U.S. person within the meaning of
Regulation S under the U.S. Securities Act of 1933, as amended (the
"Securities Act"), and is not purchasing the Shares for the account or
benefit of a U.S. person and, at the time the buy order for the Shares is
being or was originated, is or was outside the United States.

          2. The Purchaser has such knowledge and experience in financial
and business matters to be capable of evaluating the merits and risks of
its investment in the Shares, and the Purchaser and any accounts for which
it is acting are each able to bear the economic risk of its or their
investment.

          3. The Purchaser has received and has access through its own
resources to such information as it deems necessary or appropriate in order
to make its investment decision. The Purchaser has conducted its own
investigation of the Shares and the Company and acknowledges that it has
not relied on the Company, the Selling Shareholders, Lehman Brothers or any
of their respective affiliates or any person acting on their behalf with
respect to its decision to invest in the Shares, and none of such persons
has made any representation to the Purchaser, express or implied, with
respect to the Shares or the Company.

          4. The Purchaser will not hold the Selling Shareholders, Lehman
Brothers, any of their respective affiliates or any persons acting on their
behalf liable for any misstatements in or omissions from publicly available
information about the Shares or the Company.

          5. The Purchaser will comply with all applicable laws and
regulations in each jurisdiction in which it is or may be subject to any
securities laws, in all cases at its own expense.

          6. The Purchaser understands that the offer and sale to it of the
Shares have not been registered under the Securities Act and that such
offer and sale are being made to it in reliance on an exemption from the
registration requirements of the Securities Act.

          7. The Purchaser understands and agrees that the Shares purchased
by it in this offer and sale cannot and will not be deposited in any
depositary receipt facility established or maintained by a depositary bank
including, in particular, the Company's unrestricted American Depositary
Receipt facility, for at least prior to the 40th day following the
consummation of its purchase of the Shares.

          8. The Purchaser agrees that, for so long as the Shares purchased
by it in this offer and sale are restricted securities, it will not offer,
sell, pledge or otherwise transfer such Shares except (a) to the Company or
any of its subsidiaries, (b) in an offshore transaction effected on
Euronext Paris S.A. in accordance with Rule 903 or Rule 904 of Regulation S
under the Securities Act (and not in a pre-arranged transaction resulting
in the resale of such Shares into the United States), or (c) for at least
prior to the 40th day following the consummation of its purchase of the
Shares, to a U.S. person, in the United States or to any person located in
the United States.

          9. The Purchaser agrees that in the case of any offer, sale,
pledge or other transfer of any Shares purchased by it in this offer and
sale made pursuant to clause 8 above, it will deliver to each person to
whom it transfers Shares notice of restrictions on transfer of such Shares.

          10. The Purchaser is acquiring the Shares for its own account or
for one or more accounts (each of which is a non-U.S. person within the
meaning of Regulation S) as to each of which it exercises sole investment
discretion and for each of which it has full power to make the
acknowledgements, representations and agreements act forth herein on behalf
of each such account.

          11. The Purchaser is not acquiring the Shares with a view to
distribution thereof or with any present intention of offering or selling
any Shares, provided that the disposition of its property and property of
any accounts for which it is acting as fiduciary will remain at all times
within its control.

          12. The Purchaser acknowledges that it shall pay all stamp duty,
stamp duty reserve tax, issue, registration, transfer or other taxes or
duties (including any applicable interest and penalties thereon) payable on
or in connection with the sale and delivery of the Shares purchased by it.

          13. The Purchaser covenants that the foregoing representations,
warranties and covenants will be true and accurate as of, and acknowledge
that such representations, warranties and covenants shall survive, the date
of the acceptance thereof.

          14. The Purchaser recognizes that the Selling Shareholders and
Lehman Brothers will rely upon the truth and accuracy of the foregoing
investment representations and agreements. The Purchaser agrees that if any
of the representations or warranties made by it herein are no longer
accurate, it shall promptly notify the Selling Shareholders and Lehman
Brothers.



                                                                  EXHIBIT C

                           [LETTERHEAD OF FFHSJ]

                                                                212-859-8000
                                                            (FAX: 212-859-4000)

March __, 2005

Lehman Brothers International (Europe)
25 Bank Street
London E14 5LE
England

Dear Sir or Madam:

     We have acted as special counsel for CGG Investors, LLC, a Delaware
limited liability company ("CGG"), and GF Ltd. Transaction Partnership,
L.P., a Delaware limited partnership ("GF and, together with CGG, the
"Sellers") in connection with the Placement Agency Agreement, dated as of
March __, 2005, among Lehman Brothers International (Europe) ("Lehman") and
the Sellers (the "Agreement"). This opinion is delivered to you pursuant to
paragraph 7(c) of the Agreement. With your permission, all assumptions and
statements of reliance herein have been made without any independent
investigation or verification on our part, and we express no opinion with
respect to the subject matter or accuracy of such assumptions or items
relied upon.

     In connection with this opinion, we have (i) investigated such
questions of law, (ii) examined originals or certified, conformed or
reproduction copies of such agreements, instruments, documents and records
of the Sellers, such certificates of public officials and such other
documents and (iii) received such information from officers and
representatives of the Sellers as we have deemed necessary or appropriate
for the purposes of this opinion.

     In all such examinations, we have assumed the legal capacity of all
natural persons, the genuineness of all signatures, the authenticity of
original and certified documents and the conformity to original or
certified documents of all copies submitted to us as conformed or
facsimile, electronic or reproduction copies. As to various questions of
fact relevant to the opinions expressed herein, we have relied upon, and
assume the accuracy of, statements and warranties contained in the
Agreement and certificates and oral or written statements and other
information of or from representatives of the Sellers and others and assume
compliance on the part of all parties to the Agreement with their covenants
and agreements contained therein.

     Based upon the foregoing, and subject to the limitations,
qualifications and assumptions set forth herein, we are of the opinion
that:

     1.   Each of the Sellers has the requisite limited liability company
          or partnership, as applicable, power and authority to execute and
          deliver the Agreement.

     2.   Each of the Sellers has taken all necessary limited liability
          company or partnership, as applicable, action to authorize the
          execution, delivery, and performance of its obligations under the
          Agreement, and the Agreement has been duly executed and delivered
          by each of the Sellers (to the extent that execution and delivery
          thereof is governed by the Limited Liability Company Act of the
          State of Delaware or the Revised Uniform Limited Partnership Act
          of the State of Delaware).

     The opinions expressed herein are limited to the Limited Liability
Company Act of the State of Delaware and the Revised Uniform Limited
Partnership Act of the State of Delaware, each as currently in effect; and
no opinion is expressed with respect to any other laws or any effect that
such other laws may have on the opinions expressed herein. This opinion
letter is limited to the matters stated herein and no opinion is implied or
may be inferred beyond the opinions expressly stated herein. The opinions
expressed herein are given only as of the date hereof, and we undertake no
responsibility to update or supplement this opinion letter after the date
hereof for any reason.

     The opinions expressed herein are solely for your benefit in
connection with the Agreement and may not be relied on in any manner or for
any purpose by any other person or entity and may not be quoted or referred
to in whole or in part without our prior written consent.

                                            Very truly yours,




                            FRIED, FRANK, HARRIS, SHRIVER & JACOBSON LLP



                                                                  [EXHIBIT D]

[Extract from minutes of the strategic committee of Compagnie Generale de
Geophysique dated 7 March 2005]