The scale of hydraulic fracturing operations in the Marcellus shale region of the eastern United States is so vast it threatens to produce more wastewater than disposal efforts can handle, an analysis by researchers at Duke and Kent State universities found.
In hydraulic fracturing, large volumes of water, sand and chemicals are injected deep underground into gas wells at high pressure to crack open shale rock and extract embedded natural gas.
Hydraulically fractured natural gas wells in Pennsylvania produce only about 35 percent as much wastewater per unit of gas recovered as conventional wells, the researchers said, but the total amount of wastewater from natural gas production in the region has increased by about 570 percent since 2004 as a result of increased fracking production.
"It's a double-edged sword," Kent State biogeochemist Brian Lutz said. "On one hand, shale gas production generates less wastewater per unit. On the other hand, because of the massive size of the Marcellus resource, the overall volume of water that now has to be transported and treated is immense.
"It threatens to overwhelm the region's wastewater-disposal infrastructure capacity," said Lutz, who made the analysis while a postdoctoral research associate at Duke.
The researchers analyzed gas production and wastewater generation for 2,189 gas wells in Pennsylvania.
"This is the reality of increasing domestic natural gas production," Martin Doyle, Duke professor of river science said. "There are significant tradeoffs and environmental impacts whether you rely on conventional gas or shale gas."