Announces a New 3D Seismic Program in the Green Canyon/Atwater Valley Area of the Gulf of Mexico.

Houston, Texas, July 26, 2000 -- TGS-NOPEC Geophysical Company today announced the start of a new non-exclusive 3D seismic survey covering portions of the Green Canyon and Atwater Valley areas of the Gulf of Mexico. This survey will provide oil and gas companies with more than 1,700 square kilometers of new non-exclusive 3D data to aid in the development and exploration of hydrocarbons.

The Green Canyon/Atwater Valley 3D is being acquired and processed in partnership with Compagnie Generale de Geophysique (CGG). CGG’s M/V Mistral began seismic acquisition of this 74 OCS block area on July 15, 2000. This new survey is adjacent to the 660 OCS blocks of modern, high quality 3D data acquired in the Mississippi Canyon area earlier in the year and when completed, will extend TGS-NOPEC’s industry-leading 3D coverage in the eastern half of the Gulf of Mexico to 1,182 contiguous blocks (27,200 square kilometers). TGS-NOPEC plans to continue to expand the coverage of 3D data in this trend, which includes the densest concentration of deepwater production and discoveries in the Gulf.

TGS-NOPEC is a leading global provider of non-exclusive seismic data and associated products to the oil and gas industry. Oil companies use this seismic data to explore for and develop oil and gas deposits. TGS-NOPEC specializes in the planning, acquisition, processing, interpretation, and marketing of non-exclusive surveys worldwide. The company places a strong emphasis on providing high quality seismic data and the highest level of service to the industry. TGS-NOPEC also offers proprietary seismic acquisition and processing services, as well as gravity and aeromagnetic surveys.

TGS-NOPEC is listed on the Oslo Stock Exchange (OSLO:TGS).