There is a recent Gannet news report on gas from Devonian shale formations (which includes the Marcellus shale) being found in four drinking water wells in Susquehanna County, PA. How did gas gas from 6,000 feet deep make its way into ground water near the surface? According to this article, one theory is that gas traveled up gas well bores and leaked out through the annular spacing between the smaller well pipe and the larger surface drill hole. I recommend visiting the West Virginia Surface Owners’ Rights Organization website on “How a gas well is drilled down into the ground, and what can go wrong” to further understand how this could happen. I am illustrating the theory the PA DEP is currently pursuing with a few relevant slides from their website.
Susan Riha, WRI Director