TGS Expands 3D Multi-client Seismic Data Library in Sierra Leone

HOUSTON – TGS will commence acquisition of multi-client 3D seismic data in offshore Sierra Leone later this month. This survey marks over ten years of investment for TGS in the West African region and will add 2,535 km2 to the existing TGS data library. The new 3D seismic will provide important data for continued exploration on the Sierra Leone segment of the West Africa Transform Margin, where recent discoveries have established that a working hydrocarbon system exists.

The M/V GeoCarribean will acquire the 2011 survey. Data processing will be performed by TGS and available to clients in Q1 2012.

The survey is supported by industry funding.

TGS-NOPEC Geophysical Company (TGS) provides global geoscience data products and services to the oil and gas industry for the exploration and delineation of hydrocarbon reserves. We design and acquire multi-client data projects worldwide that make up our data library of seismic, gravity/magnetic and well data, enhanced by our seismic imaging technology and regional interpretation expertise.

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 product 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).