Mandatory Notice of Trade

New Share Capital

ASKER, NORWAY (23 August 2011) In reference to the
decision made by the shareholders of TGS-NOPEC
Geophysical Company ASA (TGS) at the Annual General
Meeting on 7 June 2011 to cancel 741,701 treasury
shares held, the cancellation of these shares has now
been registered in the Company Register in
Brønnøysund.

Furthermore, in connection with the stock option
exercises as notified by Oslo Stock Exchange on 19
August 2011, 51,750 new shares have now been
registered in the Company Register for exercises from
the 2009 option plan secured by warrants.

The Share Capital of TGS is after the transactions
NOK 25,850,593.50 consisting of 103,402,374 shares at
a nominal value of NOK 0.25 per share. The balance of
treasury shares held is 1,548,500 shares.

This information is subject of the disclosure
requirements acc. to §5-12 vphl(Norwegian Securities
Trading Act)


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.
TGS-NOPEC Geophysical Company ASA is listed on the
Oslo Stock Exchange (OSLO:TGS).

For additional information about this mandatory
notice of trade, please contact:

Kristian Johansen
Chief Financial Officer
Office: +47 667 69931
Cell: +47 47 60 33 34
Email: kristian.johansen@tgsnopec.com

Karen El-Tawil
VP, Business Development
Office: +1 713 860 2102
Cell: +1 713 806 2420
Email: karen.el-tawil@tgsnopec.com