CNOOC Limited manages China's offshore oil and gas exploration and production activities, in partnership with international oil and gas firms. Under Chinese government-regulated production sharing contracts, CNOOC Limited has the sole right to acquire up to 51% of any successful discovery offshore China made by foreign partners. CNOOC Limited has 2.6 billion barrels of oil equivalent in estimated proved reserves, primarily in the South China Sea. CNOOC Limited is also engaged in oil refining, natural gas processing, and refined products marketing. The oil producer has a net production of 469.4 barrels of oil equivalent per day. To grow it global assets, in 2012 the company agreed to buy Nexen for $15 billion.