CGG Closes Offering of Senior Notes Due 2015

Compagnie Generale de Geophysique (ISIN: FR0000120164 - NYSE: GGY) announces the successful closing of its offering of U.S.$165 million of 7 1/2% Senior Notes due 2015. The offering, announced on April 18, 2005, was made in reliance on Rule 144A and Regulation S under the U.S. Securities Act of 1933. There was no offering of notes to the public in France.

The net proceeds will be used to redeem and pay accrued interest on all outstanding aggregate principal of our existing 10 5/8% Senior Notes due 2007. We anticipate the redemption of the 10 5/8% Senior Notes due 2007 will occur at the end of May 2005.

The Senior Notes will not be registered under the Securities Act and may not be offered or sold in the United States absent registration or an applicable exemption from the registration requirements of the Securities Act.