TGS-NOPEC Geophysical Company ASA andWavefield Inseis ASA jointly announced that the boards of directors of both companies had entered into an Integration Agreement to merge and create TGS Wavefield.

Today, 20 August 2007, TGS and Wavefield Inseis are pleased to announce that the boards of directors of both companies have entered into a formal Merger Plan. The Merger Plan is consistent with the Integration Agreement previously entered into by both companies.

A copy of the Merger Plan and associated documentation has been mailed to shareholders in both companies. The Merger Plan will form the basis for a vote on the merger at General Meetings of both TGS and Wavefield Inseis. Both boards unanimously recommend that shareholders vote in favor of the merger of TGS and Wavefield Inseis.

Following the signing of the Merger Plan today, the boards of both companies will continue to collaborate on preparing notices for the General Meetings which will be distributed to shareholders separately, together with an Information Memorandum about the merger. It is anticipated that the notification of the General Meetings and Information Memorandum will be mailed to shareholders in early September. The General Meetings are anticipated to be held on or around 20 September 2007. The merger is expected to be completed by the end of November 2007.

Under the terms of the Merger Plan, and as previously agreed to under the terms of the Integration Agreement, the board of directors of TGS and Wavefield Inseis have agreed upon an exchange ratio whereby each Wavefield Inseis shareholder will receive 0.505 TGS shares for every 1 Wavefield Inseis share.