Increased gas production in the Marcellus shale region has led to a 570% surge in the amount of wastewater produced during the extraction process since 2004. But contrary to popular perceptions, natural gas wells where hydraulic fracturing is used generate less wastewater per unit of gas recovered compared to conventional wells, according to a study conducted by researchers from Duke University and Kent State University.
The team based its analysis on gas production and wastewater generation data for 2,189 wells in Pennsylvania. The information was obtained from publicly available reports filed by gas producers with the Pennsylvania Department of Environmental Protection. Kent State biogeochemistry assistant professor Brian Lutz, who led the research project, said that gas production through fracking generated about 35% as much wastewater per unit of gas recovered as wells where conventional drilling was employed. On average, the amount of wastewater produced by fracked wells exceeded about 10 times that generated by conventional wells but the former also delivered about 30 times more gas, Lutz noted.
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The researchers were also surprised to discover that gas well operators in the Marcellus shale classified most of the wastewater generated from fracking as brine: only about one-third was entered as flowback. The fracking controversy has focused predominantly on flowback because of the chemicals contained in it. However, brine contains certain pollutants whose treatment can be as problematic as that of many chemicals found in flowback.
While fracking may produce less wastewater (proportionally speaking), the constantly growing use of this drilling technique in the Marcellus shale remains a challenge due to the overall surge in wastewater generation. Fracking operations in the region have reached a scale that threatens local wastewater disposal capacity, the report adds.