SCHLUMBERGER 1998 STOCK OPTION PLAN

Exhibit 10.4

SCHLUMBERGER 1998 STOCK OPTION PLAN

(As Established Effective January 21, 1998,

and conformed to include amendments through January 1, 2009)

This Stock Option Plan (the “Plan”) is intended as an incentive to key employees of Schlumberger Limited (the “Company”) and its subsidiaries. Its purposes are to retain employees with a high degree of training, experience and ability, to attract new employees whose services are considered unusually valuable, to encourage the sense of proprietorship of such persons and to stimulate the active interest of such persons in the development and financial success of the Company.

(a) The Board of Directors shall appoint and maintain a Compensation Committee (the “Committee”) which shall consist of at least three (3) members of the Board of Directors, none of whom is an officer or employee of the Company, who shall serve at the pleasure of the Board. The Committee may from time to time grant incentive stock options and non-qualified stock options (“Stock Options”) under the Plan to the persons described in Section 3 hereof. No member of such Committee shall be eligible to receive Stock Options under this Plan during his or her tenure on the Committee. Members of the Committee shall be subject to any additional restrictions necessary to satisfy the definition of “Non-Employee Director” as set forth in Rule 16b-3 under the United States Securities Exchange Act of 1934 (the “Act”) as it may be amended from time to time.

(b) The Committee shall have full power and authority to interpret the provisions of the Plan and supervise its administration. All decisions and selections made by the Committee pursuant to the provisions of the Plan shall be made by a majority of its members. Any decision reduced to writing and signed by a majority of the members shall be fully effective as if adopted by a majority at a meeting duly held. Subject to the provisions of the Plan, the Committee shall have full and final authority to determine the persons to whom Stock Options hereunder shall be granted, the number of shares to be covered by each Stock Option except that no optionee may be granted options for more than 1,000,000 shares during the life of the Plan, and whether such Stock Option shall be designated an “incentive stock option” or a “non-qualified stock option.”

(c) No member of the Committee shall be liable for anything done or omitted to be done by him or by her or any other member of the Committee in connection with the Plan, except for his or her own willful misconduct or as expressly provided by statute.

(d) If the exercise period of an outstanding Stock Option is continued following a holder’s termination of employment as provided in Section 5, and the holder engages in “detrimental activity” as described in Section 5, the Committee shall have the authority in its discretion to cause such option to be forfeited and certain option exercises thereunder to be rescinded as provided for in Section 5.

(a) The persons eligible for participation in the Plan as recipients of Stock Options shall include only employees of the Company or its subsidiary corporations as defined in Section 424(f) of the Internal Revenue Code of 1986 as amended from time to time (the “Code”), and hereinafter referred to as “subsidiaries” who are executive, administrative, professional or technical personnel who have responsibilities affecting the management, direction, development and financial success of the Company or its subsidiaries. No Director of the Company who is not also an employee is eligible to participate in the Plan, nor is any employee who owns directly or indirectly stock possessing more than five percent (5%) of the total combined voting power or value of all classes of stock of the Company or any subsidiary. An employee may receive more than one grant of Stock Options at the Committee’s discretion including simultaneous grants of different forms of Stock Options.

(b) The Committee in granting Stock Options hereunder shall have discretion to determine the terms and conditions upon which such Stock Options may be exercisable. Each grant of a Stock Option shall be confirmed by an Agreement consistent with this Plan which shall be executed by the Company and by the person to whom such Stock Option is granted. Except in the case of death or disability (as described in Section 5(c)(iv)(B) or 5(c)(v)(B)), no Stock Option shall vest or become exercisable with respect to any portion of the shares of Common Stock thereunder unless and until the recipient remains in the employment of the Company or a subsidiary for a period of at least one (1) year from the date of grant of the option (which provision shall not be construed to impair in any way the right of the Company or subsidiary to terminate such employment). For the avoidance of doubt, in no event shall the provisions of the preceding sentence apply to any Stock Option held by an optionee whose employment terminated due to death or disability prior to January 17, 2008.

(c) For purposes of this Plan, employment with the Company shall include employment with any subsidiary of the Company, and Stock Options granted under this Plan shall not be affected by an employee’s transfer of employment from the Company to a subsidiary, from a subsidiary to the Company or between subsidiaries.

(d) The purchase price of the shares as to which a Stock Option is exercised shall be paid in full at the time of the exercise subject to such rules, procedures and restrictions as the Committee may prescribe from time to time: (i) in cash or by certified check; (ii) by the delivery of shares of Schlumberger Common Stock with a fair market value (as determined according to Section 5(b) of the Plan) at the time of exercise equal to the total option price; or (iii) by a combination of the methods described in (i) and (ii).

Subject to adjustment as provided in Section 8 hereof, there shall be subject to the Plan 12,000,000 shares of Common Stock, par value $0.01 per share, of the Company (the “Shares”). The Shares subject to the Plan shall consist of authorized and unissued shares or previously issued shares reacquired and held by the Company or any subsidiary. Should any Stock Option expire or be terminated prior to its exercise in full and prior to the termination of the Plan, the Shares theretofore subject to such Stock Option shall be available for further grants under the

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Plan. Until termination of the Plan, the Company and/or one or more subsidiaries shall at all times make available a sufficient number of Shares to meet the requirements of the Plan. After termination of the Plan, the number of Shares reserved for purposes of the Plan from time to time shall be only such number of Shares as are issuable under then outstanding Stock Options.

(a) Stock Options granted under this Plan which are designated as “incentive stock options” may be granted with respect to any number of Shares, subject to the limitation that the aggregate fair market value of such Shares (determined in accordance with Section 5(b) of the Plan at the time the option is granted) with respect to which such options are exercisable for the first time by an employee during any one calendar year (under all such plans of the Company and any subsidiary of the Company) shall not exceed $100,000. To the extent that the aggregate fair market value of Shares with respect to which incentive stock options (determined without regard to this subsection) are exercisable for the first time by any employee during any calendar year (under all plans of the employer corporation and its parent and subsidiary corporations) exceeds $100,000, such options shall be treated as options which are not incentive stock options. No Stock Options shall be granted pursuant to the Plan after January 21, 2008.

(b) The purchase price of each Share subject to a Stock Option shall be determined by the Committee prior to granting a Stock Option. The Committee shall set the purchase price for each Share at either the fair market value (the “Fair Market Value”) of each Share on the date the Stock Option is granted, or at such other price as the Committee in its sole discretion shall determine, but not less than one hundred percent (100%) of such Fair Market Value. After it is granted, no Stock Option may be amended to decrease the purchase price and no Stock Option may be granted in substitution for an outstanding Stock Option with a purchase price lower than the purchase price of an outstanding Stock Option. The Fair Market Value of a Share on a particular date shall be deemed to be the mean between the highest and lowest composite sales price per share of the Common Stock in the New York Stock Exchange Composite Transactions Quotations, as reported for that date, or, if there shall have been no such reported prices for that date, the reported mean price on the last preceding date on which a composite sale or sales were effected on one or more of the exchanges on which the Shares were traded shall be the Fair Market value.

(c) (i) Subject to the requirements of Section 3(b), each Stock Option granted hereunder shall be exercisable in one or more installments (annual or other) on such date or dates as the Committee may in its sole discretion determine and communicate to the optionee in communicating the grant of the option, provided that no Stock Option may be exercised after the expiration of ten (10) years from the date such option is granted (the maximum term established by the Committee with respect to a particular Stock Option is hereinafter referred to as the “Option Period”). For the avoidance of doubt, in no event shall the provisions of this Section 5(c)(i) apply to any Stock Option held by an optionee whose employment terminated due to death or disability prior to January 17, 2008.

(ii) Except as provided in paragraph (e) below, the right to purchase Shares shall be cumulative so that when the right to purchase any Shares has accrued such Shares or any part thereof may be purchased at any time thereafter until the expiration or termination of the Stock Option.

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(iii) At any time after the granting of any such Stock Option, the Committee may accelerate the installment exercise dates (subject, however, to any applicable limitations concerning options designated “incentive stock options”).

(iv) Termination of Employment and Subsequent Events.

(A) If the optionee’s employment with the Company is terminated with the consent of the Company and provided such employment is not terminated for cause (of which the Committee shall be the sole judge), the Committee may permit such Stock Option to be exercised by such optionee at any time during the period of three (3) months after such termination or the remainder of the Option Period whichever is less, provided that such option may be exercised only to the extent it was exercisable on the date of such termination.

(B) In the event an optionee dies while in the employ of the Company, any outstanding Stock Option shall automatically become fully vested and exercisable by the person or persons entitled thereto unde