Water reuse and desalination stand to decrease depletion of freshwater resources
The Permian sedimentary basin, which covers much of dry West Texas and overlaps the southeastern corner of New Mexico, is experiencing a fracking-driven oil boom that is perhaps the most noteworthy example of the larger boom going on in the United States and Canada.
Drilling operations in the Permian have tripled over the past two years, spiking oil production to a staggering 3.2 million barrels a day in May 2018. In February, it had already driven total U.S. oil production above 10.2 million barrels a day, breaking the old record of 10 million barrels set in 1970. In April, an average of 449 Permian drilling operations were in progress, amounting to 44% of those in the entire U.S. and 22% of all the rigs drilling in the world.
Water Use in Fracking
Hydraulic fracturing, or fracking, uses large quantities of water as a component of fracking fluid, which is injected into underground rock formations at high pressure, fracturing the rock to stimulate oil or gas production. Included in the fluid are proppants, which are sand, ceramic pellets, or other small particles that keep the fractures open.
After injection, underground pressure forces the fracking fluid back to the surface. This fluid, known as flowback and produced water (FP), presents a disposal problem because it contains combinations of fracking fluid chemicals, natural brines, metals, radioactive material, and hydrocarbons. It is usually stored before treatment, disposal, or recycling. Deep injection disposal is common, but it has the drawback of virtually removing from the hydrosphere, but FP water also may be recycled or treated and discharged into surface water bodies or into aquifers.
Fracking’s Draw on Freshwater Resources
Despite the economic stimulation from the boom, in some quarters concern is rising, much of it over fracking’s growing draw on freshwater resources. A new study by Duke University researchers details that increase.
Unsurprisingly, as the most productive fracking region, the Permian Basin also posted the largest increase in water use, a staggering 770%. Wells averaged 4,900 m3 in 2011, but by 2016, the average had risen to 42,500 m3. Completing a fracking well takes only 10-14 days.
While Permian region fracturing operations used the most water, fracking water use was also on the rise in other regions. The Marcellus region in Pennsylvania posted the lowest increase at 20%. In the Bakken region, straddling parts of Montana, North Dakota, Saskatchewan, and Manitoba, wells used an average only 21,100 m3 each throughout 2016, the lowest per-well consumption among the regions studied. Bucking the trend, the Haynesville Shale, centered on the Texas-Louisiana line, actually posted a decrease in water use.
Generation of FP water has increased over time, with especially elevated rates after 2014. The Eagle Ford region in Southern Texas experienced a 610% rise in FP water in its oil-producing area and a 1,440% spike in its gas-producing area. The lowest FP water increase was from the Niobrara region, which lies just east of the Rockies.
Environmental Concerns and Options
Although fracking water withdrawals constitute a fraction of total U.S. withdrawal, the large volume of water used for fracking tends to generate opposition, particularly in dry regions where groundwater is in short supply. But recent focus on recycling municipal wastewater for use in fracking fluid and advances in the treatment of FP water could alleviate environmental concerns and lower water requirements of the fracking process. Although investment has been limited so far, FP water can be treated for reuse as fracking fluid.
Desalination of briny FP water has so far been cost-prohibitive, but new advances both in portability and efficiency of desalination technology and water reuse stand to widen its application. One of the most promising developments is the increase in decentralized water treatment technologies, which bring treatment to exactly where it’s needed.