** FILE ** In this June 25, 2012 photo, a crew works on a gas drilling rig at a well site for shale based natural gas in Zelienople, Pa. (AP Photo/Keith Srakocic)

Photo by: Keith Srakocic

** FILE ** In this June 25, 2012 photo, a crew works on a gas drilling rig at a well site for shale based natural gas in Zelienople, Pa. (AP Photo/Keith Srakocic)