There’s a new study out this week from researchers at Duke University and Kent State University that concludes:
… Developing the Marcellus shale has increased the total wastewater generated in the region by about 570% since 2004, overwhelming current wastewater disposal infrastructure capacity.
Hydraulically fractured natural gas wells in the Marcellus shale region of Pennsylvania produce only about 35 percent as much wastewater per unit of gas recovered as conventional wells, according to the analysis, which appears in the journal Water Resources Research.
“We found that on average, shale gas wells produced about 10 times the amount of wastewater as conventional wells, but they also produced about 30 times more natural gas,” said Brian Lutz, assistant professor of biogeochemistry at Kent State, who led the analysis while he was a postdoctoral research associate at Duke. “That surprised us, given the popular perception that hydraulic fracturing creates disproportionate amounts of wastewater.”
However, the study shows 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 shale gas production there.
“It’s a double-edged sword,” 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.”
In the study, researchers analyzed gas production and wastewater generation for 2,189 gas wells in Pennsylvania, using publicly available data reported by industry to that state’s Department of Environmental Protection. (Keep in mind that, in West Virginia, wastewater from Marcellus drilling reportedly goes mostly to underground injection wells, not to treatment facilities).
Among other findings, the researchers discovered that well operators classified only about a third of the wastewater from Marcellus wells as “flowback from hydraulic fracturing”. Most of it was classified as “brine,” the salty water that can be generated by wells over much longer periods of time than flowback.” This brine can also be very tricky to treat, the researchers said.
Co-author Martin Doyle, professor of river science at Duke’s Nicholas School of the Environment, said:
A lot of attention to date has focused on chemicals in the flowback that comes out of a well following hydraulic fracturing. However, the amount of brine produced — which contains high levels of salts and other natural pollutants from shale rock — has received less attention even though it is no less important.
We need to come up with technological and logistical solutions to address these concerns, including better ways to recycle and treat the waste on site or move it to places where it can be safely disposed. Both of these are in fact developing rapidly.
Opponents have targeted hydraulic fracturing as posing heightened risks, but many of the same environmental challenges presented by shale gas production would exist if we were expanding conventional gas production.
And Doyle said:
This is the reality of increasing domestic natural gas production. There are significant tradeoffs and environmental impacts whether you rely on conventional gas or shale gas.