As the scale of fracking increases, states and operators are rethinking produced water management
Hydraulic fracturing, or fracking, is a technique for stimulating production in an oil or gas well by injecting large quantities of pressurized fluid, which creates fissures. Each well is different, but according to StateImpact Pennsylvania, fracking requires an average of 4.4 million gallons of water per well — enough to fill more than six Olympic swimming pools.
With persistent drought and water scarcity in many parts of the world — including in Oklahoma and other states — using fresh water for oil and gas production puts stress on water sources that are needed for drinking water and irrigation.
Fracking fluid often includes water recycled from fracking, or “flowback water,” public water system water, surface water from natural bodies of water, proppants (including sand) to keep the fractures open, salt, and “chemicals to dissolve minerals, kill bacteria, thicken the fluid, [and] prevent corrosion of pipe.”
Water that has been used in the oil and gas exploration and extraction process is called “produced water.” It typically has been disposed of in deep injection wells. But with fracking wells in the United States multiplying more than tenfold between 2000 and 2015 to approximately 300,000 wells, as reported by the U.S Energy Information Agency’s Today in Energy, the challenges of both sourcing water and disposing of produced water are motivating both states and operators to find new strategies, one of which is a new emphasis on the reuse of produced water.
Produced Water Reuse in Oklahoma
There are many factors that motivate Oklahoma to encourage produced water reuse, such as a limited supply of fresh water, and areas with many operations in close proximity. Brian Walzel of E&P Hart Energy, in his report on the Hart Midcontinent Water Forum, quoted Michael Dunkel, Vice President of Industrial Water at CH2M, as saying, “Fundamentally, oil and gas [water] reuse is the easiest way to go.”
Another argument for reuse is that a major method of produced water disposal, deep well injection, has been linked to an increase in seismic activity.
When calculating costs for alternatives to deep injection wells, such as those associated with pipelining for reuse, savings from decreased seismic activity and concurrent increased public favor may rightfully find their way to the bottom line.
The Oklahoma Water Resource Board recommended in its Water for 2060 Produced Water Reuse and Recycling report that to make expensive infrastructure for transporting produced water for reuse worth the outlay, even with a much cheaper reuse process, a resource-sharing team effort among organizations would still be necessary to make it financially attractive.
The initial investment in infrastructure to move the water from one site to another, however, has been too high for most operators. So, initial interest in expanding reuse of produced water has been focused on tight oil plays, where many fracking operations are concentrated in a limited area, which limits the distance the produced water must be transported to the treatment site.
Decentralized Treatment for Reuse
So far, major investment in produced water reuse has been limited to a few companies. Relatively isolated explorations are not able to share costs and resources, making the investment in reuse less attractive.
Because of the high cost of infrastructure, decentralized water treatment makes sense. Water can be treated in containerized water treatment plants, which can be moved from one well to the next as needed.
Sharon Dunn of The Greely Tribune explained, “Fracking takes about two to three days in what is roughly a 10- to 14-day process of drilling and completing a well.” Treatment may be scaled up by simply adding more units.