TGS Commences a Second 3D Multi-Client Seismic Survey Offshore Northwest Australia

PERTH, AUSTRALIA--(Marketwire - Dec 20, 2011) - TGS has commenced acquisition of a new 3D multi-client seismic survey, Mary Rose Northeast, which covers 3,100 km² over the Exmouth Plateau in the Carnarvon Basin, offshore NW Australia. This survey is located over parts of blocks WA-365-P, WA-346-P and W10-21 to the Northeast of the previously announced NW Australia survey (Mary Rose) in October 2011. Upon completion of this survey, the TGS portfolio of 3D multi-client coverage in this highly prospective area offshore Australia will exceed 11,500 km².

The seismic data is being acquired by the M/V Geo Atlantic and will be complete in Q1 2012. A fast track volume will be available to the industry in Q2 2012 with final data available for the full survey in Q4 2012. The survey is supported by industry funding.

Company summary
TGS-NOPEC Geophysical Company (TGS) provides multi-client geoscience data and services to oil and gas Exploration and Production companies around the globe. TGS' geophysical and geological data products include multi-client seismic libraries, permanent reservoir monitoring, magnetic and gravity data, the industry's largest global database of digital well logs and regional interpretive products. TGS also provides high-end depth imaging services to help resolve complex seismic imaging problems. For more information 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).