WPX Energy, Inc., an independent natural gas and oil exploration and production company, engages in the exploitation and development of unconventional properties. Its principal areas of operation include Piceance Basin, Bakken Shale, Marcellus Shale, Powder River Basin, and San Juan Basin in the United States. The company, through its 69% ownership interests in Apco Oil and Gas International Inc., holds oil and gas concessions in Argentina and Colombia. As of December 31, 2012, the company had proved reserves of 4,650 billion cubic feet of gas equivalent (Bcfe) comprising 4,491 Bcfe of domestic reserves and 159 Bcfe of international reserves. WPX Energy, Inc. is headquartered in Tulsa, Oklahoma.