Water Issues Related to Transitioning from Conventional to Unconventional Oil Production in the Permian Basin

Abstract

The Permian Basin is being transformed by the "shale revolution" from a major conventional play to the world's largest unconventional play, but water management is critical in this semiarid region. Here we explore evolving issues associated with produced water (PW) management and hydraulic fracturing water demands based on detailed well-by-well analyses. Our results show that although conventional wells produce ∼13 times more water than oil (PW to oil ratio, PWOR = 13), this produced water has been mostly injected back into pressure-depleted oil-producing reservoirs for enhanced oil recovery. Unconventional horizontal wells use large volumes of water for hydraulic fracturing that increased by a factor of ∼10-16 per well and ∼7-10 if normalized by lateral well length (2008-2015). Although unconventional wells have a much lower PWOR of 3 versus 13 from conventional wells, this PW cannot be reinjected into the shale reservoirs but is disposed into nonproducing geologic intervals that could result in overpressuring and induced seismicity. The potential for PW reuse from unconventional wells is high because PW volumes can support hydraulic fracturing water demand based on 2014 data. Reuse of PW with minimal treatment (clean brine) can partially mitigate PW injection concerns while reducing water demand for hydraulic fracturing.

Conventional Oil—The Forgotten Part of the Water‐Energy Nexus

“…Annual injection of surface water and shallow groundwater ranged from 9.0 × 10 7 m 3 /year in the early 1970s (Province of Alberta ) to 1.3 × 10 7 m 3 in 2017 (Alberta Energy Regulator ). Values for the Permian Basin, between 2005 and 2015, indicate that injection of water has exceeded production of water by 1.53 × 10 9 m 3 (Scanlon et al ). Statistics are not available at the basin level in Texas, but Nicot et al () documented statewide injection of 1 × 10 9 m 3 and 4 × 10 8 m 3 of surface water and shallow groundwater by the oil industry in 1980 and 1995, respectively.…”

“…Injection in Oklahoma between 2000 and 2010 resulted in an excess of 1.32 × 10 9 m 3 of water in the subsurface (Murray ). These excess volumes are attributed to injection of produced waters from other states (Lutz et al ; Gilmore Kevin et al ), as well as fresh and brackish groundwater and surface water for EOR (Murray ; Ferguson ; Scanlon et al ).…”

“…The amount of water injected and produced for conventional and unconventional oil and gas production for (a) various periods and (b) normalized to a per year basis for the Western Canada Sedimentary Basin (WCSB; 1950‐2014) (Ferguson ), Permian Basin (2005‐2015)(Scanlon et al ), states of Oklahoma (OK; 2000‐2010) (Murray ), California (2005‐2015) (State of California Department of Conservation ), and Ohio (2011‐2017) (Shumway et al ), along with the United States total (U.S. total) produced water volume for 2012 (Veil ) and the total volume used for HVHF in the United States (USHF; 2005‐2014) (Kondash and Vengosh ).…”

“…Several studies recognized that the volumes of water involved with conventional oil production are large compared to those associated with HVHF (Nicot and Scanlon 2012;Murray 2013;Kondash et al 2017;Scanlon et al 2017), suggesting that impacts to groundwater from EOR and SWD might be more likely than HVHF. Large volumes of water are injected into both conventional oil reservoirs for EOR and nonproductive reservoirs for SWD in the United States (Clark and Veil 2009) at over 180,000 wells (EPA 2017).…”

“…The amount of water injected and produced for conventional and unconventional oil and gas production for (a) various periods and (b) normalized to a per year basis for the Western Canada Sedimentary Basin (WCSB; 1950-2014) (Ferguson 2015), Permian Basin (2005-2015)(Scanlon et al 2017), states of Oklahoma (OK; 2000-2010) (Murray 2013), California (2005-2015) (State of California Department of Conservation 2018), and Ohio (2011-2017) (Shumway et al 2017), along with the United States total (U.S. total) produced water volume for 2012 (Veil 2015) and the total volume used for HVHF in the United States (USHF; 2005-2014) (Kondash and Vengosh 2015).from 9.0 × 10 7 m 3 /year in the early 1970s (Province of Alberta 2006) to 1.3 × 10 7 m 3 in 2017 (Alberta EnergyRegulator 2019). Values for the Permian Basin, between 2005 and 2015, indicate that injection of water has exceeded production of water by 1.53 × 10 9 m 3(Scanlon et al 2017). Statistics are not available at the basin level in Texas, butNicot et al (2011) documented statewide injection of 1 × 10 9 m 3 and 4 × 10 8 m 3 of surface water and shallow groundwater by the oil industry in 1980 and 1995, respectively.…”