10-K 2002

Exhibit 99.1

CERTIFICATION PURSUANT TO

18 U.S.C. SECTION 1350

AS ADOPTED PURSUANT TO

SECTION 906 OF THE SARBANES-OXLEY ACT OF 2002

In connection with the Annual Report of Schlumberger N.V. (Schlumberger Limited), (the “Company”) on Form 10-K for the period ending December 31, 2002 as filed with the Securities and Exchange Commission on the date hereof (the “Report”), I, Andrew Gould, Chairman and Chief Executive Officer of the Company, certify, pursuant to 18 U.S.C. § 1350, as adopted pursuant to § 906 of the Sarbanes-Oxley Act of 2002, that:

1 The Report fully complies with the requirements of section 13(a) or 15(d) of the Securities Exchange Act of 1934;

and

2 The information contained in the Report fairly presents, in all material respects, the financial condition and result of operations of the Company.

/s/    Andrew Gould        

Andrew Gould

Chairman and Chief Executive Officer

Date:    February 27, 2003

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