TGS 3rd quarter 2005 update

10 October 2005OSE

Naersnes, Norway (10 October, 2005) - Based on preliminary reporting from operating units, TGS management now expects net revenues for the third quarter of 2005 to be approximately USD 70 million, bringing estimated net revenues for the first nine months of 2005 to approximately USD 164 million, 45% higher than the first nine months of 2004. As a result, management now believes it is more likely than not that TGS will exceed its previous guidance of 30% revenue growth for the full year of 2005.

As communicated on numerous previous occasions, TGS' revenue stream remains largely composed of late sales from the Company's data library. The exact timing and magnitude of such sales is difficult to forecast, and quarter-to-quarter revenue fluctuations are common. In addition, there are currently uncertainties related to how oil company exploration spending pattern during Q4 2005 will be affected by the disruptions of hurricanes Katrina and Rita in TGS' largest market, the Gulf of Mexico.

These storms adversely impacted field operations on the two surveys the Company was acquiring in the Gulf of Mexico during the quarter; the Deep Resolve and the Sophie's Link 3D projects, resulting in expanded timelines and higher costs than initially scheduled for these surveys. This will translate into slightly higher amortization rates than initially planned for the projects over their economic lifetime.

TGS' full 3rd quarter earnings release is scheduled for October 27th, 2005.

TGS-NOPEC offers a telephone conference hosted by CEO Hank Hamilton, VP Business Development John Adamick, and CFO Arne Helland on Tuesday, October 11th at 15:00 Norwegian time (09:00 AM New York time). A Q&A session will follow a short introduction by the management.

Norwegian attendees are invited to call 800 80 119 and
international attendees are invited to call +47 23 000 400.
Attendees may want to call 5-10 minutes before 15:00
(09:00 AM NY) hours to ensure registration and access.
To pose a question, please press *1

A replay of the Conference call will be available shortly afterwards.

To access replay of TGS NOPEC`s conference call,
dial +47- 22 76 91 21 account no.: 1193 followed by # (pound-sign)
press 1 Conference no.: 193 followed by # (pound-sign) press 1 to play.

TGS-NOPEC Geophysical Company (TGS) is a leading global provider of multi-client geoscientific data, associated products and services to the oil and gas industry. TGS specializes in the creation of non-exclusive seismic surveys worldwide. The company also provides advanced depth imaging solutions and software through its TGS Imaging division. A2D Technologies, a wholly-owned subsidiary, is the energy industry's well log data marketplace offering the largest online database, immediate delivery, conversion services, data management services and worldwide well log data sourcing. The TGS family of companies 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 that are difficult to predict, and are based upon assumptions as to future events that may not prove accurate. These factors include TGS' reliance on a cyclical industry and principal customers, TGS' ability to continue to expand markets for licensing of data, and TGS' ability to acquire and process data products at costs commensurate with profitability. Actual results may differ materially from those expected or projected in the forward-looking statements. TGS undertakes no responsibility or obligation to update or alter forward-looking statements for any reason. TGS-NOPEC Geophysical Company ASA is listed on the Oslo Stock Exchange (OSLO:TGS).

John Adamick
Senior VP, Geological Products and Services
Tel: +1 713 860 2100