China Petrochemical Corp. (Sinopec) said on June 29 that it has completed the purchase of 50 percent of Chesapeake's share in its Mississippi Lime assets for $1.02 billion.

Chesapeake is the second largest natural gas developer in the United States and its Mississippi Lime oil and natural gas assets are in northern Oklahoma.

Sinopec signed the agreement with Chesapeake on February 23 through its wholly owned subsidiary Sinopec International Petroleum Exploration and Production Corp.

The deal means Sinopec acquires 425,000 acres (171,991 hectares) in the Mississippi Lime shale formation, with estimated proven and probable oil equivalent of 245 million barrels.

Limestone gas, along with shale gas and coalbed methane, is considered to be a source of unconventional gas.