China Petroleum & Chemical Corp (Sinopec) <600028.SS>, Asia's largest oil refiner, will buy a 50 percent stake in Chesapeake Energy Corp's Mississippi Lime oil and gas properties in Oklahoma and Kansas for $1.02 billion, a Sinopec source said.

Chesapeake, the second-largest gas producer in the United States, has about 2.1 million net acres of leasehold in the Mississippi Lime region.

Chesapeake could not be reached for comment.

Production from the Mississippi Lime region jumped 208 percent to an average of 32,500 barrels of oil equivalent per day in the fourth quarter, Chesapeake reported this month.

About 45 percent of the total output was oil, 46 percent was natural gas and the rest was natural gas liquids.

Chesapeake, which has been looking at divestments to cut down debt, said in December it would sell most of its natural gas processing and gathering assets for $2.16 billion to Access Midstream Partners LP .

Sinopec struck a deal with Devon Energy Corp in January 2012 to buy a third of the U.S. oil and natural gas producer's interest in five developing fields for about $2.2 billion.