22 July 2013, News Wires – Preliminary results of a federal US study on hydraulic fracturing have shown no evidence that chemicals used in the controversial completion process migrated into aquifers or contaminated drinking water, according to a report.
The US Department of Energy spent one year monitoring wells drilled by an unnamed explorer in Pennsylvania and found that chemicals used in fracking fluid, some of which are toxic, remained more than a mile below the surface and did not come into contact with areas that supply drinking water at shallower levels, the Associated Press reported.
The news wire cited geologist Richard Hammack, an author of the study that is still ongoing. If borne out, the results would offer a boost to unconventional oil-and-gas producers who have long maintained that the fracking process does not pose a threat to drinking water.
The study does not address other potential and indirect sources of pollution from fracking, such as surface fluid spills and shoddy well construction.
Duke University scientist Rob Jackson, who was not involved in the study, called the early results “good news” but pointed out that differing geologies and operational standards across the US could still leave open the possibility for water contamination.
In the study, Hammack and other researchers tagged drilling fluids with unique markers and injected the more than 8000 feet below the surface. The indicators did not show up in a monitoring zone 3000 feet higher, which means the fluids did not migrate far enough to come close to aquifers located between 500 and 1000 feet below the surface.
Jackson called the method a “useful and important approach” to monitoring fracking, the AP reported.
Jackson and Duke have conducted a number of studies on the impact of natural gas production on groundwater. None have revealed chemical contamination, but a recent one found evidence that methane and ethane escaped from some wells and contaminated nearby water supplies.
The US Environmental Protection Agency does not publish a baseline limit on methane allowances in drinking water.
The research, done by the National Energy Technology Laboratory in Pittsburgh, is taking place in Green County, Pennsylvania, near the state border with West Virginia. It was the first time a drilling company allowed government scientists to inject special tracers into fracking fluid and then continue monitoring for fluid migration, according to the AP.
One aspect of the latest research that was interesting to scientists, according to AP, was a finding that at least one hydraulic fracture travelled 1800 out from the wellbore, while most fractures stay within just a few hundred feet.
The researchers believe that the fracture in question may have hit naturally occurring faults – something that both industry and regulators want to avoid.
Full details of the study will be released over the next few months, AP said.