TGS-NOPEC and WesternGeco Sign Cooperation Agreement for Multiclient 3D Seismic Surveys in Norway.

Nærsnes, Norway, May 10, 2002 - TGS-NOPEC Geophysical Company ASA (OSLO:TGS) today announced the signing of an agreement with WesternGeco under which the parties will jointly invest in new multiclient 3D surveys in Norwegian waters. The agreement will cover planning, acquisition, and marketing/sales of multiclient 3D surveys in Norway during a 32-month period ending December 31, 2004.

Kjell Trommestad, VP & General Director, Europe for TGS-NOPEC stated: "The agreement reflects a perfect match combining TGS-NOPEC's large multiclient seismic 2D-base, our ability to design, market, and sell seismic projects with the extensive WesternGeco 3D vessel and data processing capacity."

The WesternGeco seismic vessel MV Regent with a 10-streamer capacity is currently mobilizing for the first multiclient 3D project in the Norwegian Sea under the new agreement.

TGS-NOPEC is a leading global provider of multiclient seismic data and associated products to the oil and gas industry. TGS-NOPEC specializes in the planning, acquisition, processing, interpretation, and marketing of multiclient surveys worldwide. TGS-NOPEC also offers proprietary seismic acquisition and processing services, as well as gravity and aeromagnetic surveys.

WesternGeco, the world's largest seismic company, provides comprehensive worldwide reservoir imaging, monitoring, and development services, with the most extensive seismic crews and data processing centers in the industry, as well as the world's most comprehensive multiclient seismic library.