Several recent studies have shown that there is no evidence that hydraulic fracturing in unconventional plays harms groundwater. These reports follow a very detailed 5-year study released earlier this year by the US Environmental Protection Agency (EPA) that found no “widespread impact” but was cautious in its conclusions.
In April, results from a 3-year study conducted by Duke University, Ohio State University, Penn State, Stanford University, and the French Geological Survey concluded that unconventional oil and gas extraction using hydraulic fracturing and horizontal drilling caused no groundwater contamination in five Northern Appalachian Basin counties in West Virginia. The study monitored water wells both before and after the installation of shale gas wells. The authors observed: “[Our report] provides a clear indication for the lack of groundwater contamination and subsurface impact from shale gas drilling and hydraulic fracturing. Saline groundwater was ubiquitous throughout the study area before and after shale gas development, and the groundwater geochemistry in this study was consistent with historical data reported in the 1980s.”
But the study also concluded that accidental spills of waste water from fracturing could threaten surface water in the region. The peer-reviewed study, which was published in the European journal Geochimica et Cosmochimica Acta, showed that methane and saline groundwater were found in some samples, but they occurred naturally in the region’s shallow aquifers and were not caused by shale activity.
Similarly, in late May the US Geological Survey released its findings after studying the impact of unconventional activity in parts of Louisiana, Arkansas, and Texas. Included in the study were the prolific production areas covering the Eagle Ford, Haynesville, and Fayetteville formations. That study concluded that unconventional oil and gas production in those areas is not a significant source of methane or benzene in drinking water wells.
This was the first study to determine the presence of those chemicals in drinking water wells in relation to the age of the groundwater. “Understanding the occurrence of methane and benzene in groundwater in the context of groundwater age is useful because it allows us to assess whether the hydrocarbons were from surface or subsurface sources,” the study said. “The ages indicated groundwater moves relatively slowly in these aquifers. Decades or longer may be needed to fully assess the effects of unconventional oil and gas production activities on the quality of groundwater used for drinking water.”
The 5-year EPA study was an update of a 2015 study that concluded that no harm to groundwater had been done by shale activity. The new study is more cautious, saying that hydraulic fracturing can contaminate water “under some circumstances.” But it said that the incidents that had occurred had been few, especially compared with the number of wells it studied.
Controversy surrounding these studies and their conclusions will continue. Additional studies are under way examining not only fracturing’s potential impact on groundwater, but on methane releases and seismic activity. And the resiliency of US unconventional activity during the price downturn indicates that this sector is here to stay.
Hydraulic Fracturing Studies
John Donnelly, JPT Editor
01 July 2017