Permian Operators Squeezed by Growing Water Pressure

Abstract

The rising tide of produced water in the Permian Basin is requiring operators to re-engineer how they manage water. One big difference in the Permian is that water production from unconventional reservoirs exceeds output from most other plays, particularly in the Delaware Basin. Prolific water production has long been a given in conventional fields there, but most of that could be reinjected to maintain production, which is not an option in the ultratight rock. Instead, billions of gallons of produced water have been pumped into saltwater disposal wells in shallow formations, such as the San Andres, significantly increasing the pressure drillers encounter, creating a hazard for drillers moving in and out of them from lower-pressure zones. To isolate the higher-pressure zones passed on the way to the Wolfcamp, operators have increased the number of strings of casing used from three to four. The increase adds about $600,000 to the cost per well, said Andrew Hunter, drilling manager for Guidon Energy, which uses the added string to isolate two underpressure zones. To maximize produced water use for fracturing, Cimarex has streamlined filtration and chemical treatments of the water in the pipeline system en route to fracture sites, limiting the need for fixed facilities, said Rita Behm, Permian exploration engineering project manager for Cimarex. Occidental Petroleum is working to manage water production while picking drilling targets. It has developed a detailed evaluation system based on a large company database that predicts production of hydrocarbons and water. High water cuts are a negative in the grading system used to choose where to spend, said John Polasek, vice president of geoscience at Occidental. All three mentioned the water issue in their presentations at the recent AAPG Global Super Basins conference on the Permian. The comments reflected the importance of dealing with water issues for operators that need to minimize fresh water use and manage injections of produced water. ExxonMobil’s XTO Energy arm is building a system to “treat produced water and reuse it again and again” to reduce its demand for fresh or brackish water wells, said Staali Gjervik, senior vice president for Permian Integrated Development at XTO. A Big Shift Addressing the problem will require an industrywide shift. Even if an operator is reusing all of its water, “they can get hammered” by the injections of a nearby commercial saltwater disposal well by an operator that is not finding other uses, Hunter said. “The only way to deal with this is to work cooperatively with other operators,” he said. When drilling through higher pressures, Hunter said drillers increase mud weight to counter the higher pore pressure in that layer, and promptly adjust it back when the pressure drops.