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