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Hydraulic Fracturing
Hydraulic fracturing is the injection of fluid under pressure to facilitate the production of oil and natural gas. This page explains the process of hydraulic fracturing, how hydraulic fracturing is regulated, and EPA’s national study on hydraulic fracturing of coalbed methane.
- How does hydraulic fracturing work?
- Does the UIC Program regulate hydraulic fracturing?
- Why does the UIC Program regulate hydraulic fracturing of coalbed methane only in Alabama?
- EPA’s national study on hydraulic fracturing of coalbed methane
How does hydraulic fracturing work?
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.
Does the UIC Program regulate hydraulic fracturing?
Sometimes. The UIC Program regulates the following activities:
- Well injection of fluids into a formation to enhance oil and gas production (Class II wells).
- Fracturing used in connection with Class II and Class V injection wells to “stimulate” (open pore space in a formation).
- Hydraulic fracturing to produce methane from coal beds in Alabama.
Why does the UIC Program regulate hydraulic fracturing of coalbed methane only in Alabama?
In 1994, the Legal Environmental Assistance Foundation (LEAF) challenged EPA because it believed Alabama’s UIC Program should regulate the injection of fluids to hydraulically fracture coal beds for methane production. EPA considered this activity stimulation associated with production (not injection) wells and not covered by the UIC Program or the Safe Drinking Water Act (SDWA).
In 1997, the Courts ruled that hydraulic fracturing of coal beds in Alabama should be regulated under the SDWA as underground injection (LEAF v. EPA, 118 F. 3d 1467). Alabama was required under the ruling to modify its UIC program. It did so, and EPA approved the revision.
The 2005 Energy Policy Act excluded hydraulic fracturing of coalbed methane from SDWA jurisdiction. No other state has been required to regulate the practice under the UIC Program.
EPA’s national study on hydraulic fracturing of coalbed methane
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. EPA retained the right, however, to conduct additional studies in the future. As a precautionary measure, the Agency also entered into a Memorandum of Agreement with companies that conduct hydraulic fracturing of CBM wells to eliminate use of diesel fuel in fracturing fluids.
- Read about EPA's Study to Evaluate the Impacts to Underground Sources of Drinking Water by Hydraulic Fracturing of Coalbed Methane Reservoirs.
- Hydraulic Fracturing Memorandum of Agreement PDF (9pp, 332K, About PDF)