CNOOC Limited, an investment holding company, engages in the exploration, development, production, and sale of crude oil and natural gas in worldwide. The company produces offshore crude oil and natural gas primarily in Bohai Sea, the Western South China Sea, the Eastern South China Sea, and the East China Sea in China. It also holds interests in various oil and gas assets in Asia, Africa, North America, South America, Oceania, and Europe. In addition, the company is involved in the sales and trading of petroleum and natural gas; oil sands exploration, development, and production; and exploration, development, and production of unconventional natural gas resources in onshore China, as well as in shale oil and gas activities. The company was incorporated in 1999 and is based in Hong Kong. CNOOC Limited operates as a subsidiary of CNOOC (BVI) LTD.