Chesapeake Energy ( CHK) signed a deal to buy Columbia Natural Resources, an Appalachian Basin natural gas producer, from Triana Energy Holdings for $2.2 billion in cash.

The purchase will provide Oklahoma City-based Chesapeake with an estimated 2.5 trillion cubic feet of additional natural gas equivalent of probable and proved reserves. Taking into account the acquisition, Chesapeake will own an estimated 13.5 tcfe of proved and unproved oil and natural gas reserves, consisting of 7.1 tcfe of proved reserves and 6.4 tcfe of unproved reserves.

Columbia's assets are mainly located in West Virginia, Kentucky, Ohio, Pennsylvania and New York and represent a new region for Chesapeake's operations. The company said the Appalachian Basin is ripe for deep-exploration activities.

"We are very enthusiastic about moving into the large, prolific and generally underexplored and unconsolidated Appalachian Basin," Chesapeake Chief Executive Aubrey McClendon said in a press release. "The basin covers over 185,000 square miles (almost three times the size of Oklahoma) across seven states and has produced more than 46 tcfe of gas from over 400,000 wells."

Chesapeake expects the deal to close no later than Dec. 15.

The company's shares changed hands at $39.55, up 69 cents, or 1.8%, in after-hours trading.