Hydraulic fracturing (fracking)

Article By:

Gallegos, Tanya J. Eastern Energy Resources Science Center, U.S. Geological Survey, Reston Virginia.

Last reviewed:January 2018

DOI:https://doi.org/10.1036/1097-8542.326700

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• Hydraulic fracturing (fracking), published April 2018:Download PDF Get Adobe Acrobat Reader
• Hydraulic fracturing (fracking), published June 2014:Download PDF Get Adobe Acrobat Reader

A well stimulation technique, commonly referred to as “fracking,” that is part of a larger process of the development of unconventional oil and gas wells. During hydraulic fracturing, oil and gas operators inject a treatment fluid into an oil or gas well at a pressure high enough to fracture the host rock so as to stimulate or increase the production of oil or gas from a low-permeability reservoir (Fig. 1). The coupling of hydraulic fracturing and horizontal drilling has increased oil and gas production in the United States in recent years. Between 2000 and 2015, the proportion of U.S. natural-gas production from hydraulically fractured wells increased from 7% to 67%, while the proportion of U.S. crude oil production from hydraulically fractured wells increased from 2% to 50%. Hydraulic fracturing, however, has also led to environmental concerns such as high water consumption, migration of contaminated fluids or stray gases from the wellbore, induced seismicity related to the perturbation of preexisting faults by the injection of large volumes of water into formations, and spills of hydraulic fracturing fluids or wastewaters. Because hydraulic fracturing applications, chemicals used, amounts of water used, types of geological formations targeted, and methods of hydraulic fracturing have changed over time and vary depending on the basin, the potential for both oil and gas production and environmental impacts varies across the United States. See also: Aquifer; Natural gas; Petroleum; Petroleum engineering

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