The US National Academy of Sciences has said that the cause of drinking water being contaminated by natural gas near hydraulic fracturing operations was faulty wells, not the drilling operations themselves. Eight clusters of contaminated wells near fracking operations in Texas and Pennsylvania were studied.
Researchers from the universities of Ohio, Duke, Stanford, Dartmouth and Rochester used ‘geo-chemical forensics’ to determine the path that the gas was taking beneath the Earth’s surface.
They found no evidence that horizontal drilling or hydraulic fracturing of shale deposits caused the natural-gas contamination at the 130 wells they examined.
Instead, there was evidence of failures in the cement process used to make the wells. Robert Poreda, professor of geo-chemistry at the University of Rochester, said: “Many of the leaks probably occur when natural gas travels up the outside of the borehole — potentially thousands of feet — and is released directly into drinking-water aquifers.
"These results appear to rule out the migration of methane into drinking-water aquifers from depth because of horizontal drilling or hydraulic fracturing, as some people feared.”