There are important distinctions between the fracking around Pavillion and the fracking used in major new shale oil and gas plays, such as Marcellus, Bakken and Haynesville. In shale plays, industry typically fractures rock from the horizontal leg of deep wells located at depths of one to three kilometres.
In Wyoming, the fracturing happens from vertical wells – an important difference – that are shallower, ranging from a kilometre to 372 metres below the surface. Some water wells in the area go down to 244 metres, creating a relatively close linkage.
In addition, the EPA notes what may be imprudent industry practices. Only two gas wells around Pavillion have “surface casing” – a protective metal sleeve inside a well that is cemented in place to prevent drilling fluids from leaking out – that goes deeper than the deepest water wells. That means almost every gas well has unprotected stretches at depths people draw water from.
The EPA itself, in a news release Thursday, said conditions in Wyoming are “different from those in many other areas of the country.” But in an interview, spokesman Larry Jackson said it’s possible that what’s happened at Pavillion has “commonalities that could result in similar findings elsewhere.”