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Water Management Techbook 2018

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6 | April 2018 | hartenergy.com WATER MANAGEMENT: OVERVIEW "There's a huge lack of data and data availability in the marketplace, which is a shame, because when you're looking at the overall costs, 40% is water," Rothbarth said. "So just a little bit of intelligence on the water side could save companies a lot of money." He also said that in many cases, such as in Texas, water information is not publicly available, and oper- ators typically keep such information private. In those cases, Digital H2O implements machine-learning algo- rithms to estimate water production history based off well production data that are publicly available. Bourgier said companies that implement an ana- lytics approach to water management could likely see cost savings and risk mitigation in their operations. "Finding reliable freshwater sources and manag- ing the produced water from operations both involve costs," she said. "Minimizing operational costs for water management through process optimization using analytics will lower the overall operating costs of the company." Seismicity issues One of the effects of managing large amounts of the water produced during hydraulic fracturing has been induced seismicity events, particularly since 2008. The USGS has identified 17 areas in the central and eastern U.S. that have experienced induced seismicity events as a result of produced water injection into disposal wells, with Okla- homa being by far the most prevalent. Accord- ing to the USGS, the number of earthquakes with a magnitude (m) of 2.7 or greater in Oklahoma increased from fewer than 500 in 2010 to more than 4,000 in 2016. However, Mirko van der Baan, a professor at the University of Alberta in the Department of Physics, who spoke at a Society of Exploration Geophysicists event in Houston in December 2017, said, except for Oklahoma, areas with high produced water injection rates are not necessarily prone to earthquakes. At the event, van der Baan cited the Bakken and Marcellus basins as regions that have seen substan- tial increases in production during the past several years but have experienced little to no seismic events. He said despite about a 700% increase in gas pro- duction in the Marcellus Basin since 2010, there has been "no significant increase" in seismic events measured above a 3 m. In recent years, a few clustered locations in the Permian Basin have experienced increased seismic activity, particularly west of the Pecos River in Reeves County. According to TexNet, an online earthquake catalog run by the University of Texas at Austin's Bureau of Economic Geology, there were five 3 m to 3.5 m earthquakes in the Pecos region between Jan. 1, 2017, and March 5, 2018. However, van der Baan said that even with an increased number of saltwater disposal wells in the Permian, no seismicity issues have been formally associated with them. He said areas with lower seismic hazards are less prone to induced seismicity, but the opposite is not necessarily true. "It's not as simple as 'I do disposal wells, therefore I will have seismicity,'" van der Baan said. According to Laura Capper, president and CEO of EnergyMakers Advisory Group, seismicity issues are always locally defined, with each shale region featuring unique attributes that may interact with other local attributes. Capper said there are more than a dozen factors that must be in place to generate an induced seismic event (Figure 1). In places like Oklahoma, regulators have put into place restrictions on produced water injection practices, which has led to a reduction in seismicity events in the state, according to the Oklahoma Water Resources Board (OWRB). The challenge behind solving seismicity issues, Capper said, is that "the real action takes place miles underground, in most cases, where we have very limited access to good data." She said there is ongoing debate among lead- ing researchers on whether seismicity trends will continue, increase or decrease when drilling and production levels ramp up and when more produced water is injected into underground reservoirs. "I personally do not believe we have learned how to completely eliminate induced seismicity, but I do believe it can be well-managed and mitigated with sound operational practices and local insights about high-risk zones," Capper said. "Transporting fluids farther or implementing local recycling to reduce injected volumes can impact operating margins, so a rationalized, balanced approach is required. But it is doable. I don't think we are completely out of the woods yet, but I do think we'll get there." Trends in regulations Since the tremendous growth in North American hydrocarbon production via hydraulic fracturing starting in 2010, federal and state regulatory agen- cies have worked to keep pace with a fast-mov- ing industry. Mandates by agencies such as the U.S. Environmental Protection Agency, the Texas Railroad Commission (RRC) and OWRB have put into place regulations managing water practices,

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