Massachusetts Institute of Technology (2010)

“The protection of freshwater aquifers from fracture fluids has been a primary objective of oil and gas field regulation for many years. As indicated in Table 2.2, there is substantial vertical separation between the freshwater aquifers and the fracture zones in the major shale plays. The shallow layers are protected from injected fluid by a number of layers of casing and cement — and as a practical matter fracturing operations cannot proceed if these layers of protection are not fully functional. Good oil-field practice and existing legislation should be sufficient to manage this risk.”