There is no evidence that chemicals used from fracking, or hydraulic fracturing, during the natural gas drilling process moved up to contaminate drinking water aquifers at a western Pennsylvania drilling site, the Department of Energy said.
After a year of monitoring, the researchers in a federal study found the chemical-laced fluids used to free gas trapped deep below the surface stayed thousands of feet below the shallower areas that supply drinking water, said geologist Richard Hammack.
Although the results are preliminary — the study is still ongoing — they are a boost to a natural gas industry that continues to fight complaints from environmental groups and property owners who say fracking is dangerous.
Drilling fluids tagged with unique markers injected more than 8,000 feet below the surface, but did not end up detected in a monitoring zone 3,000 feet higher. That means the potentially dangerous substances stayed about a mile away from drinking water supplies.
“This is good news,” said Duke University scientist Rob Jackson, who was not involved with the study. He called it a “useful and important approach” to monitoring fracking, but cautioned the single study doesn’t prove that fracking can’t pollute, since geology and industry practices vary widely in Pennsylvania and across the nation.
The boom in gas drilling has led to tens of thousands of new wells drilled in recent years, many in the Marcellus Shale formation that lies under parts of Pennsylvania, New York, Ohio and West Virginia. That led to major economic benefits but also fears the chemicals used in the drilling process could spread to water supplies.
The mix of chemicals varies by company and region, and while some end up listed openly, the industry complained that disclosing special formulas could violate trade secrets. Some of the chemicals are toxic and could cause health problems in significant doses, so the lack of full transparency worries landowners and public health experts.
The study done by the National Energy Technology Laboratory in Pittsburgh marked the first time that a drilling company let government scientists inject special tracers into the fracking fluid and then continue regular monitoring to see whether it spread toward drinking water sources. The research occurred at a drilling site in Greene County, which is southwest of Pittsburgh and adjacent to West Virginia.
Officials monitored eight new Marcellus Shale horizontal wells seismically and they injected one with four different man-made tracers at different stages of the fracking process. That process involves setting off small explosions to break the rock apart. The scientists also monitored a separate series of older gas wells about 3,000 feet above the Marcellus to see if the fracking fluid reached up to them.