Well construction and geology may both play a role
Courtesy of Robert B. Jackson
Drinking water from wells near hydraulic fracturing operations in Pennsylvania and New York contains more methane than samples taken farther away, a new study finds. The results point to faulty construction and local geology as contributing factors.
Local geology “absolutely matters,” says environmental scientist Robert Jackson of Duke University who led the work. Similar studies in Arkansas have not found evidence of methane infiltrating drinking water wells.
Chemical signatures suggest that some of the 141 wells contain gases that may have bubbled up from relatively shallow rock layers. But in six drinking water wells near drilling sites, the chemical signatures of some of the gases — including methane, ethane, propane and helium — and the mix of those gases suggest that they may have originated deeper down.
Two problems with the construction of wells for hydraulic fracturing, or fracking, may have contributed to drinking water contamination, researchers propose June 24 in the Proceedings of the National Academy of Sciences. If cement seals in the upper part of the fracking well fail, gas from an intermediate layer can drift up into drinking water. In the six drinking water wells containing gases that appear to have originated much deeper down, steel lining the fracking well might be faulty, potentially allowing chemical-laden water injected into fracking wells to seep into surface waters.
R.B. Jackson et al. Increased stray gas abundance in a subset of drinking water wells near Marcellus shale gas extraction. Proceedings of the National Academy of Sciences. Published June 24, 2013. doi:10.1073/pnas.1221635110 [Go to]
R. Ehrenberg. The facts behind the frack. Science News. Vol. 182, September 8, 2012, p.20. [Go to]