Hydraulically fractured natural gas wells are producing less wastewater per unit of gas recovered than conventional wells would. But the scale of fracking operations in the Marcellus shale region is so vast that the wastewater it produces threatens to overwhelm the region's wastewater disposal capacity, according to new analysis by researchers at Duke and Kent State universities.
Hydraulically fractured natural gas wells in the Marcellus shale region of Pennsylvania produce only about 35% 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% 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."