A hydrogeologist from Penn State says companies drilling in the Marcellus Shale play through hydraulic fracturing (hydrofracking) are recycling about two-thirds of the wastewater that returns to the surface.
David Yoxtheimer, a researcher with the university's Marcellus Center for Outreach and Research, presented his findings Sunday at the annual Geological Society of America conference in Pittsburgh.
"The regulatory framework is such that there are higher costs to take wastewater to a treatment facility that is permitted to treat and dispose of that water, plus more higher costs for them to get more fresh water and haul it in," Yoxtheimer told NGI's Shale Daily on Tuesday. "By recycling the wastewater, they can reduce their transportation costs and the overall environmental footprint of the industry."
According to Yoxtheimer, gas wells drilled in the Susquehanna River Basin -- which includes about 50% of Pennsylvania and a large portion of New York -- on average use about 3.7 million gallons of fluid per well. He said about 89% of the fluid used, 3.3 million gallons, is fresh water and the remaining 400,000 gallons, about 11%, is reused flowback.
Yoxtheimer found that the 30-day average recovery of flowback totaled between 8% and 10%. He said that from June 2008 to May 2010, drilling companies had reused about 44.1 million gallons and disposed of 21 million gallons, a recycling rate of nearly 67%.
"Each company has its own unique approach to recycling," Yoxtheimer said. "Some companies may directly reuse it, diluting it with fresh water until the chemical quality meets their standards. Others are doing some level of treatment, either with mobile treatment facilities that they take out into the field or by hauling it to a centralized treatment facility. It all depends on the logistics involved."
Although the wastewater recycling figures were specifically for the Susquehanna River Basin part of the state, Yoxtheimer was confident that the rate was between 8% and 10% elsewhere in Pennsylvania as well.
"I think that's fairly representative of the entire state," he said. "Many of the companies operating inside the Susquehanna Basin are also operating outside of it, and so their operational procedures ought to be fairly consistent."
Yoxtheimer cited data from the Pennsylvania Fish and Boat Commission, which found 9.48 billion gallons of water are being extracted from surface and groundwater sources every day in Pennsylvania. Of that amount, 1.9 million gallons per day (gpd) is used in Marcellus Shale development. By comparison, thermoelectric power uses 6.43 billion gpd, the public water supply draws 1.42 billion gpd and industrial users are taking 770 million gpd.
Yoxtheimer added that most drilling companies were recycling wastewater from hydrofracking, but that economies of scale generally meant larger companies were doing it more often and more efficiently. He also said he observed most wastewater being stored in tanks and said companies were trending against the use of lined surface impoundment ponds "to reduce the potential for spills."
But he admitted that he was surprised over the rate of recycling wastewater.
"There is a wide range of numbers out there on how much reuse is actually occurring," he said. "The Susquehanna River Basin Commission does a fairly efficient job of capturing the actual reuse because they have a flowback reporting program. [But] the Department of Environmental Protection's [DEP] reporting program is fairly new, so I don't think they are fully capturing how much water is actually being recycled. That constitutes a large gap in what is being reported by the industry, and also by people for and against the industry.
"But I think what we are seeing are more and more reuses occurring."
Last week a DEP official downplayed the impact of water use in Marcellus Shale drilling, but conceded that the conclusions may be premature because only a few years worth of data had been compiled (see Shale Daily, March 21). Meanwhile the U.S. Environmental Protection Agency wants Pennsylvania to test its water supplies and wastewater for radioactivity, after several New York Times articles claimed that wastewater threatened the state's water supplies (see Shale Daily, March 9; March 1).