Source: Dow Jones News Service, June 26, 2013
Posted on: http://envfpn.advisen.com
(FROM THE WALL STREET JOURNAL 6/26/13)
Poorly sealed natural-gas wells — not hydraulic fracturing of shale-rock formations — are likely to blame for dissolved gas found in private water wells in Pennsylvania, according to a new study by Duke University.
Duke scientists found that 82% of the 141 water wells they tested in a part of Pennsylvania above the rock formation known as the Marcellus Shale had elevated levels of methane, the main component of natural gas.
Water wells nearer to natural-gas-industry drilling sites had the highest levels according to the study, published online this month by the Proceedings of the National Academy of Sciences.
However, the study found no evidence that hydraulic fracturing, or fracking, the process of using water and chemicals to crack shale formations deep underground and unlock trapped oil and gas, was causing fluids to migrate upward into drinking aquifers closer to the surface.
Instead, it concluded that wells being drilled were most likely not adequately sealed, allowing gas to flow upward and sometimes enter aquifers used by homes. The combination of steel pipes, called casing, and cement sheaths used in well construction don’t always contain gas as intended, industry officials and observers contend.
“Poor casing and cementing problems are the simplest explanation of what we found,” said Rob Jackson, a professor of environmental sciences at Duke and lead author of the study, which was funded by the university.
Environmentalists have criticized fracking as an industrial threat to rural communities and their drinking water.
Steve Everley, a spokesman for Energy in Depth, a group funded by the Independent Petroleum Association of America, said the Duke study “is not a smoking gun to say that gas drilling is a problem.” He noted how other recent research has found high levels of methane in water wells, even when there hasn’t been nearby fracking.