1. MARCELLUS SHALE
Study on stray gas in Pa. water wells 'rules out a biological source'
As Rob Jackson and his fellow researchers delve into concerns about stray natural gas contaminating Pennsylvania drinking water wells, they're finding that not all of it comes from the Marcellus Shale. Some of it comes from layers of rock between the productive Marcellus gas formation and the surface, formations that companies aren't trying to produce, said Jackson, a biology professor at Duke University. That gas likely works its way up into aquifers from those middle layers through gaps and cracks in the cement seal that is supposed to encase the steel wellbore near the surface, he said.