Energize Weekly, August 29, 2018
Water demand for fracking and the flowback and produced water from fracked wells has soared with the amount of water being used up as much as 770 percent and flowback volumes increasing up to 1,440 percent in six years, according to a Duke University study.
The increased water use and wastes in shale oil and gas regions are in large part spurred by longer horizontal wells, which are generating more production. The horizontal portion of the well, called a lateral, has increased as much as 80 percent between 2011 and 2016.
Modeling by the Duke researchers projects that if drilling activity returns to the highs of 2010, demand for water will grow 50-fold by 2030. Even if prices and drilling rates remain stable, the models still show a large increase by 2030 in both water use and waste production.
The increasing water demand and the large volumes of flowback and produced water could pose problems in some regions, particularly semi-arid regions such as Texas’ Permian Basin, the researchers said.
“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 Avner Vengosh, professor of geochemistry and water quality at Duke’s Nicholas School of the Environment and a study co-author.
The Duke researchers analyzed six years of data from more than 12,000 wells in all the major U.S. shale and tight sands plays. They also combined several databases to estimate the efficiency of production of both gas and oil production and water use and modeled the data over different future scenarios.
“Recent studies have suggested that intensification of the hydraulic fracturing process through drilling longer horizontal laterals has resulted in increased water use and hydrocarbon production,” the analysis said.
Water demand in five basins—the Niobrara, Permian, Eagle Ford, Bakken and Marcellus—increased during the six-year period. There was a slight decline in water intensity in the Haynesville Shale, which covers part of Arkansas, Louisiana and Texas. The length of horizontal wells also varied by basin.
While water intensity in fracking wells has increased dramatically, the water used for fracking nationally remains “negligible” in comparison to other industrial water users, the Duke study said.
“On a local scale, however, water use for hydraulic fracturing can cause conflicts over water availability, especially in arid regions such as western United States, where water supplies are limited,” the study said.
The oil-producing Permian Basin in West Texas and New Mexico saw the largest increase in water use, a 770 percent jump, to 42,500 cubic meters of water per well in 2016 from 4,900 cubic meters in 2011. At the same time, the length of horizontal wells in the Permian increased 79 percent to around 2,500 meters. It was the sharpest increase in lateral length among the basins.
The Marcellus Shale, a natural gas play in Pennsylvania and West Virginia, had the lowest increase in water use, 20 percent—27,950 cubic meters per well in 2016 up from 23,400 cubic meters in 2011. The increase in lateral length in the Marcellus was 20 percent, similar to the increase in water use.
The Bakken, in North Dakota, has the lowest median water use among the basins—21,100 cubic feet of water per well in 2016, and water use per well decreased slightly in the Haynesville during the study period.
In all basins the flowback water generation was also increasing over time with particularly higher rates after 2014. The study found gas and oil portions of the Eagle Ford, in South Texas, showed a 610 percent increase in flowback water in the oil-bearing areas—reaching 16,900 cubic meters per well in 2015 and a 1,440 percent increase in the gas-bearing section to 20,700 cubic meters of water per well in 2015.
The smallest increase in flowback water occurred in the Niobrara region, in Colorado, where production increased from 1,800 cubic meters per well in 2011 to 2,300 cubic meters per well in 2016, a 28 percent rise.
The period from 2014 to 2015 marked a “turning point” as oil prices dropped and producers scaled back on the number of new wells, but increased the water volumes used in wells that were fracked, and so, rates of water use and flowback increased, the analysis said.
The modeling done by the Duke researchers shows that if prices for oil and gas return to their 2010 levels, cumulative water use and wastewater volumes could surge up to 50-fold in shale regions.
“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 lead author of the study.
“New drilling technologies and production strategies have spurred exponential growth in unconventional oil and gas production in the United States 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.”
