, Norway (6 August, 2009) - TGS has noticed an error in the 2009 proprietary contract revenue expectations in the Outlook section of the Earnings Release for Q2 2009 issued this morning.

The last paragraph of that section should read:

TGS management's expectations for the full year 2009 remain unchanged as follows: multi-client library investments of USD 230-270 million, average pre-funding in the range of 45-55% of investments, an average annualized multi-client amortization rate in the range of 35-40% of net revenues, net revenues in the range of USD 470-530 million, and proprietary contract revenues in the range of 5-10% of total net revenues. The Company will continue to evaluate opportunities to increase multi-client investments and grow its market share during the year based on client interest and other economic indicators.

The information on outlook in the TGS Q2 slide presentation is correct as originally submitted.

The corrected Earnings Release is posted on the TGS website. TGS apologizes for this oversight.

Updated 2nd Quarter 2009 Earnings Release