By Patrick Miller
New research from the University of Texas at Austin found that recycling produced water from hydraulic fracturing in the Permian Basin can reduce the need for large upfront water requirements and potentially reduce seismic earthquakes caused by reinjecting the water into geologic formations.
The study—conducted by the university’s Bureau of Economic Geology—was published this month in Environmental Science & Technology and highlights key differences in water use between conventional drilling and fracking. It found that recycling produced water from fracked wells could help reduce potential problems associated with the technology.
"What I think may push the reuse of produced water a little more are concerns about over pressuring, and potential induced seismicity," said Bridget Scanlon, the study’s lead author and director of the bureau's Sustainable Water Resources Program. "In the Permian, we have a good opportunity for reusing or recycling produced water for hydraulic fracturing."
Marc Engle, chief of a U.S. Geological Survey program on water use associated with energy production, said that the study provides a comprehensive, data-driven look into how water is managed in the rapidly changing Permian Basin, providing stakeholders with a detailed view of water inflows and outflows.
The study proposes that rather than injecting produced water, operators could potentially reuse the water from unconventional wells to frack the next set of wells. Researchers said enough water is produced in the Midland and Delaware basins of the Permian to support fracking. In addition, the water requires only minimal treatment—clean brine—to be suitable for reuse.
Although the Permian Basin has seen active oil production since the 1920s, conventional production peaked in the 1970s. Fracking technology revived production in the basin by enabling producers to tap into less permeable shale formations, turning what was once a conventional play into an unconventional play. The study analyzed 10 years of water data from 2005-2015. Researchers tracked how much water was produced and how it was managed from conventional and unconventional wells. They compared those volumes to water use for hydraulic fracturing. The average volume of water needed per well has increased by about 10 times over the past decade, according to the study, with a median value of 250,000 barrels or 10 million gallons of water used per well in the Midland Basin in 2015. However, unconventional wells produce far less water than conventional wells, averaging about three barrels of water per barrel of oil versus 13 barrels of water per barrel of oil from conventional wells.
Although there is enough produced water for reuse, Scanlon said that infrastructure, questions about produced water ownership, and low cost of fresh or brackish groundwater may currently keep disposal practices as they are. But as unconventional operations in the Permian grow, reusing produced water may become more attractive.
"Reuse and recycling is an option, and the industry is good at adapting," she said.