press release

Obo-1 Well Encounters Hydrocarbons in Nigeria/Sao Tome & Principe Development Zone's Block 1

LOCAL NEWS RELEASE: Issued in Lagos, Nigeria

LAGOS, May 26, 2006 -- The Nigeria – Sao Tome & Principe Joint Development Authority, Chevron and its co-venturers Esso Exploration and Production Nigeria-Sao Tome (One) Limited, and Dangote Energy Equity Resources, have encountered hydrocarbons in the Obo-1 exploration well in Block 1 of the Nigeria – Sao Tome and Principe Joint Development Zone.

The Obo-1 well logged a cumulative total of at least 150 feet (45 meters) of net hydrocarbon pay in multiple reservoirs and provided important reservoir rock and liquid samples, which need to be evaluated and integrated into the interpretation of the Obo Area to determine the next step of the appraisal process. At this stage, it is premature to determine whether or not Chevron and its co-venturers have made a commercial discovery.

The Obo-1 well is located in 1,720 meters of water (5, 640 feet) and the drilling operation was completed in 63 days on March 15th 2006.

The JDZ Block-1 is located approximately 190 miles (300 kilometers) north of the city of Sao Tome and approximately 125 miles (200 kilometers) south of the city of Port Harcourt in Nigeria. Chevron JDZ Limited has a 51 percent equity share in the block while Esso Exploration and Production Nigeria-Sao Tome (One) Limited, and Dangote Energy Equity Resources have the remaining 40 and 9 percent equity, respectively.

Updated: May 2006