FILE PHOTO: A mixture of oil, diesel fuel, water and mud sprays as roughnecks wrestle pipe on an oil drilling rig outside Watford, North Dakota, October 20, 2012. REUTERS/Jim Urquhart/File Photo
FILE PHOTO: A mixture of oil, diesel fuel, water and mud sprays as roughnecks wrestle pipe on an oil drilling rig outside Watford, North Dakota, October 20, 2012. REUTERS/Jim Urquhart/File Photo