The process involves the high-pressure injection of "fracking fluid" (primarily water, containing sand or other proppants suspended with the aid of thickening agents) into a wellbore to create cracks in the deep rock formations through which natural gas, petroleum, and brine will flow more freely.

[6] Drilling and hydraulic fracturing have made the United States a major crude oil exporter as of 2019,[7] but leakage of methane, a potent greenhouse gas, has dramatically increased.

[8][9] Increased oil and gas production from the decade-long fracking boom has led to lower prices for consumers, with near-record lows of the share of household income going to energy expenditures.

[17] Opponents of fracking argue that these are outweighed by the environmental impacts, which include groundwater and surface water contamination,[18] noise and air pollution, the triggering of earthquakes, and the resulting hazards to public health and the environment.

[19][20] Research has found adverse health effects in populations living near hydraulic fracturing sites,[21][22] including confirmation of chemical, physical, and psychosocial hazards such as pregnancy and birth outcomes, migraine headaches, chronic rhinosinusitis, severe fatigue, asthma exacerbations and psychological stress.

[41] Harold Hamm, Aubrey McClendon, Tom Ward and George P. Mitchell are each considered to have pioneered hydraulic fracturing innovations toward practical applications.

[5][44] For the well treatment, 1,000 US gallons (3,800 L; 830 imp gal) of gelled gasoline (essentially napalm) and sand from the Arkansas River was injected into the gas-producing limestone formation at 2,400 feet (730 m).

Other countries in Europe and Northern Africa subsequently employed hydraulic fracturing techniques including Norway, Poland, Czechoslovakia (before 1989), Yugoslavia (before 1991), Hungary, Austria, France, Italy, Bulgaria, Romania, Turkey, Tunisia, and Algeria.

The definition of massive hydraulic fracturing varies, but generally refers to treatments injecting over 150 short tons, or approximately 300,000 pounds (136 metric tonnes), of proppant.

[48] Massive hydraulic fracturing quickly spread in the late 1970s to western Canada, Rotliegend and Carboniferous gas-bearing sandstones in Germany, Netherlands (onshore and offshore gas fields), and the United Kingdom in the North Sea.

Then, operators in Texas began completing thousands of oil wells by drilling horizontally in the Austin Chalk, and giving massive slickwater hydraulic fracturing treatments to the wellbores.

[63][64][65] According to the United States Environmental Protection Agency (EPA), hydraulic fracturing is a process to stimulate a natural gas, oil, or geothermal well to maximize extraction.

[72] Horizontal drilling involves wellbores with a terminal drillhole completed as a "lateral" that extends parallel with the rock layer containing the substance to be extracted.

[88] Radiotracers are selected to have the readily detectable radiation, appropriate chemical properties, and a half life and toxicity level that will minimize initial and residual contamination.

[89] The Nuclear Regulatory Commission publishes guidelines which list a wide range of radioactive materials in solid, liquid and gaseous forms that may be used as tracers and limit the amount that may be used per injection and per well of each radionuclide.

Geomechanical analysis, such as understanding a formations material properties, in-situ conditions, and geometries, helps monitoring by providing a better definition of the environment in which the fracture network propagates.

Hydraulic fracturing enables the extraction of natural gas and oil from rock formations deep below the earth's surface (generally 2,000–6,000 m (5,000–20,000 ft)), which is greatly below typical groundwater reservoir levels.

The multi-stage fracturing technique has facilitated the development of shale gas and light tight oil production in the United States and is believed to do so in the other countries with unconventional hydrocarbon resources.

[116] Other studies have suggested that the economic benefits are outweighed by the externalities and that the levelized cost of electricity (LCOE) from less carbon and water intensive sources is lower.

[117] The primary benefit of hydraulic fracturing is to offset imports of natural gas and oil, where the cost paid to producers otherwise exits the domestic economy.

[121] One paper found "that productivity of an irrigated crop decreases by 5.7% when a well is drilled during the agriculturally active months within 11–20 km radius of a producing township.

For example, ten people were arrested in 2013 during an anti-fracking protest near New Matamoras, Ohio, after they illegally entered a development zone and latched themselves to drilling equipment.

[138] ExxonMobil, Chevron Corporation and ConocoPhillips aired advertisements during 2011 and 2012 that claimed to describe the economic and environmental benefits of natural gas and argue that hydraulic fracturing was safe.

[139] In January 2013, Northern Irish journalist and filmmaker Phelim McAleer released a crowdfunded[141] documentary called FrackNation as a response to the statements made by Fox in Gasland, claiming it "tells the truth about fracking for natural gas".

[151] The executive summary of the report stated: "An assessment of the currently available evidence indicates that the potential risks to public health from exposure to the emissions associated with shale gas extraction will be low if the operations are properly run and regulated.

"[151]: iii A 2012 report prepared for the European Union Directorate-General for the Environment identified potential risks to humans from air pollution and ground water contamination posed by hydraulic fracturing.

[162] Extraction workers are also at risk for developing pulmonary diseases, including lung cancer and silicosis (the latter because of exposure to silica dust generated from rock drilling and the handling of sand).

[183] The magnitude of these events is usually too small to be detected at the surface, although tremors attributed to fluid injection into disposal wells have been large enough to have often been felt by people, and to have caused property damage and possibly injuries.

There are already a host of documented instances in which nearby groundwater has been contaminated by fracking activities, requiring residents with private wells to obtain outside sources of water for drinking and everyday use.

[206] In the United States, the Ground Water Protection Council launched FracFocus.org, an online voluntary disclosure database for hydraulic fracturing fluids funded by oil and gas trade groups and the U.S. Department of Energy.