TGS Signs Agreement With Dolphin for Joint 2D Multi-Client Survey in Northwest Africa

HOUSTON, TX--(Marketwire - Jun 23, 2011) - TGS has signed an agreement with Dolphin Geophysical Ltd. to jointly acquire, process and market multi-client 2D seismic data along Northwest Africa. The survey will total 25,000 km of long offset seismic data in the offshore areas of multiple countries. This program was designed based on the partnership's extensive geologic knowledge of the area. Approximately 10,000 km of seismic data has been acquired to date using the M/V Artemis Atlantic and the remaining acquisition will continue into the second half of 2011.

The data will improve the understanding of highly prospective areas along the Northwest African Passive Margin and adds to TGS' existing and continuous multi-client 2D seismic library along the African margin.

Data processing will be performed by TGS and certain data will be available to clients beginning in late 2011, with the full program completed in 2012.

Company summary
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. Visit TGS online at www.tgsnopec.com.

Forward-looking statements and contact information
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).