TGS-NOPEC ANNOUNCES ADDITIONAL 2D IN MAKASSAR STRAITS

Oslo, Norway, September 25th, 2002- TGS-NOPEC Geophysical Company today announced the commencement of Circum Makassar (CM-02), a new 4,200-kilometer non-exclusive 2D seismic program in the Makassar Straights of Indonesia.

The survey is a joint venture between TGS-NOPEC and WesternGeco and is being undertaken in cooperation with the Indonesian Directorate General of Oil and Gas (MIGAS).

The Makassar Straits borders the Mahakam Delta, the second most important production area in Indonesia. The Mahakam Delta contains 2.5 billion barrels of oil, and over 30 TCF of gas. Despite its importance as a major oil and gas province, relatively little is known of the petroleum geology of the basin outside the Mahakam Delta. Exploration of the deepwater areas is in very early stages. However, initial exploration is encouraging, as several significant discoveries have already been made.

This new program is designed to infill and complement the Circum Makassar 2001 (CM-01) program the processing of which was completed in late August 2002. The CM-01 program followed the successful Mahakam Delta-99 (MDD-99) survey acquired in the area by TGS-NOPEC. The CM-01 dataset has shown many exciting structures, often associated with spectacular amplitude anomalies. Strong similarities can be drawn between these structures and those observed in deep-water, offshore Brunei.

Both Circum Makassar programs (CM-01 and CM-02) are being prepared for a licensing round scheduled by MIGAS for late 2003.

Please find map attached:

TGS-NOPEC is a leading global provider of multi-client geoscience data and associated products and services to the oil and gas industry. TGS-NOPEC specializes in the planning, acquisition, processing, interpretation and marketing of non-exclusive seismic surveys worldwide. A2D Technologies, a wholly owned subsidiary, pioneered the delivery of digital well log data over the Internet and currently offers a one-of-a-kind integrated solution for well log data sourcing, well log data management, and well log correlation. The TGS-NOPEC group places a strong emphasis on providing high-quality data and the highest level of service to the industry.

All statements in this press release other than statements of historical fact are forward-looking statements, which are subject to a number of risks, uncertainties and assumptions. Such factors include any significant change in the oil and gas business or the economy.

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

For additional information about this new release contact:

TGS-NOPEC Geophysical Company

Paul Gilleran

Australia

Tel.: 61 8 9480 0000

e-mail: paulg@tgsnopec.com.au

Arne Helland, CFO

Norway

Tel.: +47-31 29 20 00 or +47 91887829

e-mail: arne@tgsnopec.no

Karen El-Tawil