The amount of water used per well for hydraulic fracturing surged by up to 770 percent between 2011 and 2016 in all major U.S. shale gas and oil production regions, a new Duke University study finds.
The study also discovered that the volumes of wastewater generated within the first year of oil and gas production also increased by up to 1,440 percent in the Eagle Ford region (Texas).
A well’s wastewater is comprised of mostly brines extracted with the gas and oil from deep underground, mixed with some of the water injected into the well during hydraulic fracturing. These brines are usually salty and may contain toxic and radioactive elements, making them difficult to treat and dispose of safely.
The contaminated water is often disposed of by injecting it deep underground. These injections are believed to have caused thousands of relatively small-scale earthquakes in Oklahoma in recent years.
The drilling industry’s increased use of water and other fluids to produce oil and natural gas is a result of recent changes in drilling practices. For example, well operators have increased the length of the horizontal portion of wells drilled through shale rock where reserves of oil and gas are locked up in order to make new wells more productive.
Drillers have also significantly increased the amount of water, sand, and other materials they pump into the wells to hydraulically fracture the rock. This releases more hydrocarbons trapped within the shale.
“We clearly see a steady annual increase in hydraulic fracturing's water footprint, with 2014 and 2015 marking a turning point where water use and the generation of flowback and produced water began to increase at significantly higher rates," said Avner Vengosh, professor of geochemistry and water quality at Duke’s Nicholas School of the Environment.
To conduct the study, the researchers collected and analyzed six years of data on water use and natural gas, oil, and wastewater production from industry, government, and non-profit sources for more than 12,000 individual wells located in all major U.S. shale gas and tight oil producing regions. They then used these data to model future water use and first-year wastewater volumes under two different scenarios.
"While the extraction of shale gas and tight oil has become more efficient over time as the net production of natural gas and oil from these unconventional wells has increased, the amount of water used for hydraulic fracturing and the volume of wastewater produced from each well have increased at much higher rates, making fracking's water footprint much higher," said Vengosh.
Due to these changes in the fracking process, the fossil fuel industry is increasing their efficiency out of a given well. However, the increased use of water for fracking may be bad news for freshwater.
Much of the controversy surrounding fracking revolves around the use of large volumes of water to hydraulically fracture wells, and concern is especially high in arid regions where water withdrawals can account for a significant portion of water consumption. There have been calls to increase the use of alternative water sources such as brackish water or recycling water to minimize the strain on freshwater resources.
“Water is not just some uniform resource,” said Mary Kang, a civil engineer at McGill University who studies groundwater and fracking. Water accessibility and quality are highly variable between locations—and there are parts of the water supply researchers still don’t really understand yet, like the deep groundwater that Kang studies.
Total industrial use is estimated at almost 15 billion gallons of water per day, for uses ranging from auto manufacturing to mining. On a local scale, water use for fracking can cause conflicts over water availability, especially in dry regions of the U.S. where water supplies are limited.
Freshwater availability might be the limiting factor of fuel extraction in the Permian Basin of West Texas, according to Vengosh. The oilfields are predicted to produce historic amounts of crude oil in the next few years, but without the freshwater to do it via fracking, this production wouldn’t be possible.
“The water use is part of the system that cannot be mitigated in any way,” said Vengosh.
If this rapid intensification continues, fracking's water footprint could grow by up to 50-fold in some regions by the year 2030.
"Even if prices and drilling rates remain at current levels, our models still predict a large increase by 2030 in both water use and wastewater production," said Andrew J. Kondash, a PhD student in Vengosh's lab who was lead author of the paper.
"Lessons learned from production development in the United States can directly inform the planning and implementation of hydraulic fracturing practices elsewhere as other countries such as China, Mexico, and Argentina bring their unconventional natural gas reserves online," Kondash said.
The demand for fresh water could also inspire innovation in fracking technologies. “In many places, the amount of water that’s recycled has gone up,” says Kang.
“New drilling technologies and production strategies have spurred exponential growth in unconventional oil and gas production in the U.S. and, increasingly, in other parts of the world,” Kondash said. “This study provides the most accurate baseline yet for assessing the long-term environmental impacts this growth may have, particularly on local water availability and wastewater management.”
This new study gives everyone from industry to environmentalists a new baseline for figuring out how much water will be used in fracking, and is likely to prompt at least some to reevaluate their water budgets. But the grand total left in those water budgets, and the speed at which they’ll be consumed still remains to be seen.