Hydraulic fracturing is used in oil and natural gas production. After a well is drilled into reservoir rock that contains oil, natural gas, and water, every effort is made to maximize the production of oil and gas. In hydraulic fracturing, a fluid (usually water containing specialty high-viscosity fluid additives) is injected under high pressure. The pressure exceeds the rock strength and the fluid opens or enlarges fractures in the rock. These larger, man-made fractures start at the injection well and extend as much as several hundred feet into the reservoir rock. After the formation is fractured, a “propping agent” (usually sand carried by the high-viscosity additives) is pumped into the fractures to keep them from closing when the pumping pressure is released. Hydraulic fracturing allows the oil or natural gas to move more freely from the rock pores to a production well so that it can be brought to the surface.
EPA's Underground Injection Program (UIP) does not regulate hydraulic fracturing because the 2005 Energy Policy Act excluded hydraulic fracturing from SDWA jurisdiction. In 2004, EPA conducted a study to assess the potential for contamination of USDWs from the injection of hydraulic fracturing fluids by coalbed methane (CBM) wells. Based on the information collected and reviewed at the time, EPA concluded that the injection of hydraulic fracturing fluids by CBM wells posed little or no threat to USDWs and additional studies were not justified.
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