Driller Adrian Vallarta, left, and floor hand Jose Garza attach a drill screen to the elevator on Orion Drilling Co.'s Perseus drilling rig near Encinal in Webb County, Texas, U.S., on Monday, March 26, 2012. The Perseus is drilling for oil and gas in the Eagle Ford Shale, a sedimentary rock formation underlying an area of South and East Texas. Photographer: Eddie Seal/Bloomberg via Getty Images
