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Water Management Techbook 2018

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EPmag.com | April 2018 | 39 WATER MANAGEMENT: BEST PRACTICES finding that the requirements aren't coming into play. Clients are being logical. They have all this water and they're saying, 'we need to use it instead of depositing it down a hole.'" This trend has been readily apparent in the unconventional plays, Watson said, but inquiries about reusing produced water are coming in from around the world. "That does my heart good," she said. "It's not necessarily the regulations. It's the clients looking at things and being pragmatic and saying, 'let's do something with this.'" The need to source water for the number of unconventional wells being drilled and com- pleted has driven some of the pragmatism. "The smaller operators are being squeezed for getting freshwater, and they're really pursuing reus- ing every bit of produced water they have coming out of wells because they just can't get freshwa- ter," Watson said. "You have to use your produced water. It can be challenging to get your hands on the water otherwise." In the past operators were treating small vol- umes for reuse in completing wells, but now oper- ators aim to treat and reuse nearly 60% of the estimated 800 Mbbl of water needed to complete a well, Watson said. "It's hard to get to 100% unless it's a huge produc- ing field" because it won't generate the full volume needed, Watson said. This can result in multisourcing water. "As you blend the waters, they react differently," she said. "Each field has its own water quality. Even if you mix this water with nonpotable water from the city, you wind up with elements dropping out. So there are treatment requirements." Henthorne called water quality the biggest hurdle. "It varies drastically from site to site and region to region. It even changes day to day. When you start dealing with produced water, there are so many more variables and challenges to address," she said. Offshore, there might be minimal treatment of the produced water before it is disposed of over- board. But onshore, a location without the destina- tion to dispose of the water has cost implications for the project. Much of the produced water is too salty to be used for irrigation without treatment, and salt removal treatments are costly, Henthorne said. "Much of the produced water is too saline to use a membrane for desalination, so you'd have to use [an] evaporative/thermal distillation pro- cess, which is energy- and capital cost-intensive to achieve that separation." Brandon Kern, technical service specialist with Dow Water & Process Solutions, said treatment of the water differs by its planned use. "Discharge usually has the most stringent require- ments," he said, but for completion water, it may be "good enough to pull out hydrocarbons and any chemicals that may interfere." From the outset The need for handling produced water remains unchanged, as does the lack of operator enthusi- asm for spending money on something that doesn't directly generate revenue. "The biggest problem in this industry is the pro- duced water is not a product that gives you revenue, so people don't prioritize it. They leave it to the last minute to deal with it. They're focused on oil and gas," Georgie said. "[Produced water] impacts revenue even if it doesn't give you your revenue." According to Watson, designing an appropriate produced water system requires a great deal of data. Merely pulling some gallons of water and sending it off to the laboratory only presents data from one brief period in the well's life, Watson said. "One snapshot of analytical is not going to help me design a system that's going to fit a cli- ent's needs," she said. "That's just one spot in a 24-hour day that's supposed to be indicative of every change." Watson said levels of measurable qualities like oil, water, iron, pH, particle size and solids data can change quite a lot and often throughout the course of a day, let alone the course of a well's design life. "There is a wide gap between the people who design facilities and the people who manufacture the equipment and the people who deal with produced water," Georgie said. In short, according to Georgie, design people go by the book, manufacturers tend to try to sell technology and the people actually dealing with the produced water see "it's not all lined up." Often technology will work in one specific field, perhaps at a certain temperature or pressure or with a certain type of oil, but it may not work as well in other conditions, Georgie said. Technology that works in a black oil or crude system may not work for a gas condensate system. "What is successful in one plant is not necessar- ily successful in another plant," Georgie added. "The problem that I see, being independent, is the people who design the facility do not talk to the people who operate the facilities, and they choose technology

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