Mandatory notification of shares

Rune Eng, EVP International, has on November 13th sold 263,452 shares in TGS-Nopec Geophysical Company ASA (“TGS”) at a price of NOK 111,4 per share to Eng Invest AS, which is wholly owned by Rune Eng. Following this transaction, Mr. Eng holds no shares of TGS common stock directly, holds 263,452 shares of TGS common stock beneficially through the foregoing investment company, and has the right to receive up to 60,300 shares of TGS common stock pursuant to performance and restricted share units granted by TGS, of which 39,300 units are supported by warrants that have been subscribed by Mr. Eng.

For more information, visit TGS.com or contact:

Fredrik Amundsen
Chief Financial Officer
investor@tgs.com

This information is subject to the disclosure requirements pursuant to Section 5-12 the Norwegian Securities Trading Act