Nexen Says Preliminary Reserve Estimate for Usan Significant

Nexen says the ongoing appraisal of the Usan and Ukot discoveries, located in approximately 3,250 feet of water on Block OPL 222 in the Gulf of Guinea offshore Nigeria, indicate significant hydrocarbon accumulations.

Priority has been focused on the Usan field which was discovered in 2002. In addition to the discovery well, two appraisal wells have confirmed the presence of light, sweet crude oil in multiple pay zones over a wide aerial extent. A third appraisal well is currently drilling. Based upon drilling and test results completed to date, Nexen estimates the recoverable hydrocarbon resource in this field to be at least 300 million barrels.

A second field, called Ukot, was discovered in 1998. This discovery has been confirmed by one appraisal well, located 3.5 kilometers south of the discovery well.

"Our analysis indicates a significant hydrocarbon resource which is material to Nexen," commented Charlie Fischer, Nexen's President and CEO. "We are evaluating a number of development scenarios while continuing to appraise Ukot, and have plans to test other prospects on the block with significant upside which has not been included in the current resource estimate."

Nexen has a 20% interest in Block OPL 222, in partnership with Elf Petroleum Nigeria Limited (20%), ExxonMobil (30%) and ChevronTexaco (30%). The operator on Block OPL 222, Elf Petroleum Nigeria Limited, on behalf of the joint venture partners, has applied to the Nigerian National Petroleum Corporation for granting of an Oil Mining Lease.