on offshore oil and gas assets in Nigeria, www.TheStandard.com reported. CNOOC is eyeing an offer for Nations Energy, an independent oil producer based in Canada. The move by CNOOC comes after the company announced the acquisition of a 45 percent stake in oil and gas fields owned by Nigerian oil company South Atlantic Petroleum earlier this week. The deepwater fields are contained in a 1,295-square-kilometer tract off the Niger River Delta and contain estimated recoverable reserves of 1.1 billion barrels of oil equivalent. Nine-year-old Nations first bought assets in Kazakhstan in 1997. It operates OJSC Karazhanbasmunai - Kazakhstan's ninth-largest oil producer - in the west of the country on the Caspian Sea. The company has sunk about $370 million into the Central Asian operation.