(Hong Kong, 12 Aug, 2011) - CNOOC Limited (the "Company", NYSE: CEO, SEHK: 0883) announced that, according to the latest statement by ConocoPhillips China Inc ("COPC"), the Operator of Penglai 19-3 oil field, more oil-based drilling mud (OBM) on the sea floor was identified. This addition brings the revised volume of OBM on the seabed to 400 cubic meters (2,500 barrels). The volume of oil released to the sea surface remains at 114 cubic meters (717 barrels). The total volume of fluids spilled from the incident amounts to 514 cubic meters (3,217 barrels) of oil and OBM and exceeds 240 cubic meters (1,500 barrels) as originally estimated by the Operator.

After the incident occurred, COPC has deployed substantial resources for oil recovery and cleanup work. According to COPC, its response personnel has recovered 269 cubic meters (1,700 barrels) of OBM from the seabed near the Penglai 19-3 C platform, and approximately 70 cubic meters (440 barrels) of oil/water mix from the sea surface to date.

As the non-operator, the Company has also fully utilized its resources and personnel to assist COPC on shoreline protection activities with 111 people walking approximately 3,289 kilometers of shoreline and 19 vehicles patrolled approximately 48,645 kilometers of shoreline along the Bohai Bay area by 11 August.

In order to meet the requirements set by the State Oceanic Administration, the Company will continue to urge and assist COPC to stop the leaks and complete the cleanup work by the end of August, so as to minimize the impact of the oil spill incident on the marine environment.