Study quantifies potential for water reuse inpermian basin oil production6 September 2017

A map showing the range of the Permian Basin and thedistribution of oil wells in the region. Credit: BridgetScanlon/UT Austin.

Hydraulic fracturing has once again made thePermian Basin that stretches across westernTexas and New Mexico one of the richest oil fieldsin the world. But the improved reserves come withsome serious water management issues. Drillingfor oil uses water upfront, and brings up largevolumes of water that needs to be managed.

New research led by The University of Texas atAustin Bureau of Economic Geology highlights keydifferences in water use between conventional drillsites and sites that use hydraulic fracturing, whichis rapidly expanding in the Permian.

The study, published in Environmental Science &Technology on Sept. 6, found that recycling thewater produced during operations at other

hydraulic fracturing sites could help reduce potentialproblems associated with the technology. Theseinclude the need for large upfront water use, andpotentially induced seismicity or earthquakes,triggered by injecting the water produced duringoperations back into the ground.

"What I think may push the reuse of producedwater a little more are concerns about overpressuring, and potential induced seismicity," saidlead author Bridget Scanlon, a senior researchscientist and director of the Bureau's SustainableWater Resources Program. "In the Permian wehave a good opportunity for reusing or recyclingproduced water for hydraulic fracturing."

Scanlon co-authored the study with Bureauresearchers Robert Reedy, Frank Male, and MarkWalsh. The Bureau is research unit of the UTJackson School of Geosciences.

Since the 1920s, the Permian Basin has been avery active area for conventional oil production,peaking in the 1970s and accounting for almost 20percent of U.S. oil production. Hydraulic fracturingtechnology has revived production in that area byallowing companies to tap into immense oilreserves held in less permeable unconventionalshale formations. The new technology is turning theconventional play into an unconventional play andhas almost brought oil production up to the 1970speak. The U.S. Geological Survey estimates thatPermian's Wolfcamp Shale alone could hold 20billion barrels of oil, the largest unconventionalresource ever evaluated by the Survey.

The study analyzed 10 years-worth of water datafrom 2005-2015. The researchers tracked howmuch water was produced and how it wasmanaged from conventional and unconventionalwells and compared those volumes to water use forhydraulic fracturing.

Upfront, unconventional wells use much more

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water than conventional wells. The average volumeof water needed per well has increased by about 10times over the past decade, according to the study,with a median value of 250,000 barrels or 10 milliongallons of water used per well in the Midland Basinin 2015. But unconventional wells produce muchless water than conventional wells, averaging about3 barrels of water per barrel of oil versus 13 barrelsof water per barrel of oil from conventional wells.

For conventional operations, the produced water isdisposed of by injecting it into depletedconventional reservoirs, a process that maintainspressure in the reservoir and can help bring upadditional oil through enhanced oil recovery.Unconventional wells generate only about a tenthof the water produced by conventional wells but this"produced water" cannot be injected into the shalesbecause of the low permeability of the shales. Thestudy found that the produced water fromunconventional wells is largely injected into non-oil-producing geologic formations—a practice that canincrease pressure and could potentially result ininduced seismicity or earthquakes.

The study points out that instead of injecting theproduced water into these formations, operatorscould potentially reuse the water fromunconventional wells to hydraulically fracture thenext set of wells. Enough water is produced in theMidland and Delaware basins in the Permian tosupport hydraulic fracturing water use, and thewater only needs minimal treatment (clean brine) tomake it suitable for reuse.

Marc Engle, the chief of a United States GeologicalSurvey program on water use associated withenergy production, said that the study provides acomprehensive, data-driven look into how water ismanaged in the rapidly changing Permian Basin.

"This work by Scanlon et al., for the first time,provides interested stakeholders with a detailedview of water inflows and outflows from thePermian Basin," said Engle. "Moreover, the workcaptures temporal trends through an importantperiod where the industry shifted from vertical wellsin conventional reservoirs to vertical then horizontalwells in continuous reservoirs."

Although there is enough produced water for reuse,Scanlon said that infrastructure, questions aboutproduced water ownership, and low cost of fresh orbrackish groundwater may currently keep disposalpractices as they are. But as unconventionaloperations in the Permian grow, reusing producedwater may become more attractive.

"Reuse and recycling is an option, and the industryis good at adapting," Scanlon said.

More information: Environmental Science &Technology (2017). pubs.acs.org/doi/10.1021/acs.est.7b02185

Provided by University of Texas at Austin

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APA citation: Study quantifies potential for water reuse in permian basin oil production (2017, September6) retrieved 8 April 2022 from https://phys.org/news/2017-09-quantifies-potential-reuse-permian-basin.html

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