CNOOC Limited is a producer of offshore crude oil and natural gas and an independent oil and gas exploration and production company. It mainly engages in oil and natural gas exploration, development, production and sales. It has four major production areas in offshore China, which are Bohai Bay, Western South China Sea, Eastern South China Sea and East China Sea. During the year ended December 31, 2008, it owned net proved reserves of 2.52 billion barrel of oil equivalent (BOE), including 1.58 BOE of crude oil and 5,623.3 billion cubic feet (bcf) of natural gas. In 2008, it produced an average of 422,068 barrels of crude oil and 621.1 million cubic feet (mmcf) of natural gas daily, with a total net oil and gas production of 530,728 BOE per day. It is organized into three major business segments. It is involved in the upstream operating activities of the petroleum industry that comprise independent operations, production sharing contracts with foreign partners and trading business.