Sinopec International Petroleum Exploration and Production Corp., China's second-largest oil company and largest refiner, said Tuesday it acquired a 50 percent stake in U.S.-based Chesapeake Energy Corp.'s oil and gas assets in northern Oklahoma.

The $1.02 billion deal gives Sinopec 172,000 hectares (425,000 acres) in the Mississippi Lime shale play, the Chinese energy company said in a statement.

The deal, announced shortly before fellow state-owned energy company CNOOC closed on its purchase of Canadian energy firm Nexen, calls for the companies to share all future exploration and development costs associated with the joint venture, whose operator will be Chesapeake.

"Production from these assets (including Mississippi Lime and other formations), net to Chesapeake's interest and prior to Sinopec's purchase, averaged approximately 34 thousand barrels of oil equivalent per day in the 2012 fourth quarter and, as of December 31, 2012, there was approximately 140 million barrels of oil equivalent of net proved reserves associated with the assets," Chesapeake Energy said in a statement.

Chinese oil companies have been trying to acquire assets in North America to gain experience in exploiting non-conventional energy resources, such as shale oil and gas, despite the difficulties faced in obtaining regulatory approval.

CNOOC dropped its bid to acquire U.S.-based Unocal Corp. in 2005 amid opposition from U.S. lawmakers.

U.S. supermajor Chevron Corp. eventually bought Unocal, which had large oil and gas holdings in Asia, for $17.9 billion. EFE