# Fracking

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{{Short description|Fracturing bedrock by pressurized liquid}}
{{Use dmy dates|date=November 2022}}
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{{Infobox industrial process
| name           = Fracking
| image          = Frac job in process.JPG
| caption        = Fracking the [Bakken Formation](/source/Bakken_Formation) in North Dakota
| type           = Mechanical
| sector         = [Mining](/source/Mining)
| technologies   = Fluid pressure
| feedstock      =
| product        = [Natural gas](/source/Natural_gas), [petroleum](/source/petroleum)
| companies      =
| facility       =
| inventor       = Floyd Farris, Joseph B. Clark ([Stanolind Oil and Gas Corporation](/source/Stanolind_Oil_and_Gas_Corporation))
| year           = 1947
| developer      =
}}

'''Fracking''' (also known as '''hydraulic fracturing''',  '''fracing''', '''hydrofracturing''', or '''hydrofracking''') is a [well stimulation](/source/well_stimulation) technique involving the fracturing of [formations](/source/Formation_(geology)) in [bedrock](/source/bedrock) by a pressurized liquid. The process involves the high-pressure injection of "fracking fluid" (primarily water, containing sand or other [proppants](/source/hydraulic_fracturing_proppants) suspended with the aid of [thickening agent](/source/thickening_agent)s) into a [wellbore](/source/wellbore) to create cracks in the deep-rock formations through which [natural gas](/source/natural_gas), [petroleum](/source/petroleum), and [brine](/source/brine) will flow more freely. When the [hydraulic pressure](/source/hydraulic_pressure) is removed from the well, small grains of [hydraulic fracturing proppants](/source/hydraulic_fracturing_proppants) (either sand or [aluminium oxide](/source/aluminium_oxide)) hold the fractures open.<ref name="ECStimTech"/>

Fracking, using either hydraulic pressure or acid, is the most common method for [well stimulation](/source/well_stimulation).<ref>{{cite web |title=What Are The Three Primary Methods Of Well Stimulation? |url=https://www.infinitysol.net/chemical-toll-blending-blog/what-are-the-three-primary-methods-of-well-stimulation |publisher=Infinity Energy Solutions }}{{self-published inline|date=January 2026}}</ref> Well stimulation techniques help create pathways for oil, gas or water to flow more easily, ultimately increasing the overall production of the well.<ref>{{cite book |last1=Nolan |first1=Dennis P. |title=Handbook of Fire and Explosion Protection Engineering Principles for Oil, Gas, Chemical, and Related Facilities |chapter=Overview of Oil, Gas, and Petrochemical Facilities |date=2019 |pages=33–50 |doi=10.1016/B978-0-12-816002-2.00002-7 |isbn=978-0-12-816002-2 }}</ref> Both methods of fracking are classed as ''unconventional'', because they aim to permanently enhance (increase) the permeability of the formation. So the traditional division of hydrocarbon-bearing rocks into source and reservoir no longer holds; the source rock ''becomes'' the reservoir after the treatment.

Hydraulic fracking is more familiar to the general public, and is the predominant method used in hydrocarbon exploitation, but acid fracking has a much longer history.<ref name="Van Dyke">Van Dyke JW. 1896. Increasing the flow of oil-wells. Patent No. US 556,651.</ref><ref>Grebe JJ and Stoesser SM 1935, Treatment of deep wells. Patent no. US 1,998,756,</ref><ref>{{cite journal |last1=Montgomery |first1=Carl T. |last2=Smith |first2=Michael B. |title=Hydraulic Fracturing: History of an Enduring Technology |journal=Journal of Petroleum Technology |date=2010 |volume=62 |issue=12 |pages=26–40 |doi=10.2118/1210-0026-JPT |bibcode=2010JPetT..62...26M }}</ref><ref>{{cite journal |last1=Barbati |first1=Alexander C. |last2=Desroches |first2=Jean |last3=Robisson |first3=Agathe |last4=McKinley |first4=Gareth H. |title=Complex Fluids and Hydraulic Fracturing |journal=Annual Review of Chemical and Biomolecular Engineering |date=2016 |volume=7 |pages=415–453 |doi=10.1146/annurev-chembioeng-080615-033630 |pmid=27070765 |doi-access=free }}</ref> The hydrocarbon industry tends to use ''fracturing'', although the word ''fracking'' now dominates in popular media.

==Definition==

thumb|alt=Well stimulation|Well stimulation methods. Fracking is highlighted in yellow.

Hydraulic fracturing (fracking) and acidising (acid fracking) are two of the most common methods for well stimulation. The flow chart shows that hydraulic fracking and acid fracking, highlighted in yellow, are two categories of unconventional hydraulic methods. But acidising is complicated by the fact that matrix acidising is considered conventional. Note that it takes place below the fracture gradient of the rock.{{fact|date=January 2026}}

In the UK legislative and hydrocarbon permitting context (see [Fracking in the United Kingdom](/source/Fracking_in_the_United_Kingdom)), Adriana Zalucka et al.  have reviewed the various definitions,<ref name="Zalucka">{{cite journal |last1=Zalucka |first1=Adriana |last2=Goodenough |first2=Alice |last3=Smythe |first3=David |title=Acid stimulation: Fracking by stealth continues despite the moratorium in England |journal=Energy Policy |date=2021 |volume=153 |article-number=112244 |doi=10.1016/j.enpol.2021.112244 |bibcode=2021EnPol.15312244Z }}</ref>  as well as the role of key regulators and authorities, in a peer-reviewed article published in 2021. They have proposed a new robust definition for unconventional well treatments:

{{Blockquote
|text='''All well stimulation treatments of oil and gas wells which increase the permeability of the target rock volume to higher than 0.1 millidarcies beyond a 1 m radius from the borehole.'''}}

The above definition focuses on increasing permeability, rather than on any particular extraction process. It is quantitative, using the generally agreed 0.1 md cut-off value, below which rocks are considered impermeable. It exempts borehole cleaning processes like acid squeeze or acid wash from being classed as unconventional, by using the 1 m radius criterion. It avoids a definition based on, for example, the quantity of water injected, which is controversial,<ref>{{cite journal |last1=Smythe |first1=David |last2=Haszeldine |first2=Stuart |title=Could fracking creep under the radar? |journal=Nature |date=2017 |volume=548 |issue=7668 |page=393 |doi=10.1038/548393a |pmid=28836601 |hdl=20.500.11820/e29dd520-2dce-4ba8-be2d-b1faa7ccec42 |hdl-access=free }}</ref> or the injection pressure applied (whether the treatment is above or below the fracture gradient, as shown in the flow chart above). It also exempts non-hydrocarbon wells from being classed as unconventional.{{fact|date=January 2026}}

The definition takes into account the views of the hydrocarbon industry and the US Geological Survey, in particular. A low permeability (by consensus defined as less than 0.1 millidarcies) implies that the resource is unconventional, meaning that it requires special methods to extract the resource. Above that value, conventional methods suffice. Unconventional resources are also characterised by being widely distributed, with low energy density (i.e. in a low concentration) and ill-defined in volume. There are no discrete boundaries, in contrast to those bounding a conventional hydrocarbon reservoir.{{fact|date=January 2026}}

Although the definition above was developed within the UK context, it is universally applicable.{{fact|date=January 2026}}

{{Hydraulic fracturing}}

==Hydraulic fracking==

Hydraulic fracking{{Efn|Also known as ''hydraulic fracturing'',  ''fracing'', ''fraccing'', ''hydrofracturing'', ''hydrofracking'', or simply ''fracking''.}} is the most commonly used [well stimulation](/source/well_stimulation) technique. It involves the fracturing of [formations](/source/Formation_(geology)) in [bedrock](/source/bedrock) by a pressurized liquid. The process involves the high-pressure injection of "fracking fluid" (primarily water, containing sand or other [proppants](/source/hydraulic_fracturing_proppants) suspended with the aid of [thickening agent](/source/thickening_agent)s) into a [wellbore](/source/wellbore) to create cracks in the deep rock formations through which [natural gas](/source/natural_gas), [petroleum](/source/petroleum), and [brine](/source/brine) will flow more freely. When the [hydraulic pressure](/source/hydraulic_pressure) is removed from the well, small grains of [hydraulic fracturing proppants](/source/hydraulic_fracturing_proppants) (either sand or [aluminium oxide](/source/aluminium_oxide)) hold the fractures open.<ref name="ECStimTech"/>

Hydraulic fracking began as an experiment in 1947,<ref name="KGS_PIC_32">{{Cite web |last1=Suchy |first1=Daniel R. |last2=Newell |first2=K.David |date=15 May 2012 |title=Kansas Geological Survey, Public Information Circular (PIC) 32 |url=https://www.kgs.ku.edu/Publications/PIC/pic32.html |access-date=8 October 2021 |publisher=Kansas Geological Survey}}</ref> and the first commercially successful application followed in 1949. As of 2012, 2.5 million "frac jobs" had been performed worldwide on oil and gas wells, over one million of those within the U.S.<ref>{{Citation | first=George E | last=King | url=https://www.kgs.ku.edu/PRS/Fracturing/Frac_Paper_SPE_152596.pdf | title=Hydraulic fracturing 101 | publisher=Society of Petroleum Engineers | year=2012 | id=SPE 152596 | via=[Kansas Geological Survey](/source/Kansas_Geological_Survey)}}</ref><ref name="Fracmaps" /> Such treatment is generally necessary to achieve adequate flow rates in [shale gas](/source/shale_gas), [tight gas](/source/tight_gas), [tight oil](/source/tight_oil), and [coal seam gas](/source/coal_seam_gas) wells.<ref name="Charlez"/> Some hydraulic fractures can form naturally in certain [veins](/source/vein_(geology)) or [dikes](/source/dike_(geology)).<ref name="Blundell et al">{{cite journal |last1=Blundell |first1=Derek |last2=Arndt |first2=Nicholas |last3=Cobbold |first3=Peter R. |last4=Heinrich |first4=Christoph |title=9: Processes of tectonism, magmatism and mineralization: Lessons from Europe |journal=Ore Geology Reviews |date=2005 |volume=27 |issue=1–4 |pages=333–349 |doi=10.1016/j.oregeorev.2005.07.003 |bibcode=2005OGRv...27..333B }}</ref> Drilling and hydraulic fracking have made the [United States](/source/United_States) a major [crude oil](/source/crude_oil) exporter as of 2019,<ref>{{cite news |last1=Clifford Krauss |title=The 'Monster' Texas Oil Field That Made the U.S. a Star in the World Market |url=https://www.nytimes.com/2019/02/03/business/energy-environment/texas-permian-field-oil.html |access-date=21 September 2019 |work=[The New York Times](/source/The_New_York_Times) |date=3 February 2019 |quote=The shale-drilling frenzy in the Permian has enabled the United States not only to reduce crude-oil imports, but even to become a major exporter [...] New technologies for drilling and hydraulics fracturing helped bring the break-even price}}</ref> but leakage of [methane](/source/methane), a potent [greenhouse gas](/source/greenhouse_gas), has dramatically increased.<ref>{{cite news |last1=Umair Irfan |title=The best case for and against a fracking ban |url=https://www.vox.com/energy-and-environment/2019/9/12/20857196/fracking-ban-case-democrats-2020-president |access-date=21 September 2019 |work=[Vox](/source/Vox_(website)) |date=13 September 2019 |quote=During much of the fracking boom, the US economy grew and emissions declined. One study found that between 2005 and 2012, fracking created 725,000 jobs.  That's largely due to natural gas from fracking displacing coal in electricity production.}}</ref><ref>{{Cite web |date=24 February 2017 |title=Fracking fluid is leaking more often than we thought possible |url=https://www.popsci.com/fracking-fluid-hydraulic-fracturing-spill/ |access-date=22 September 2022 |website=Popular Science |language=en-US}}</ref> 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.<ref>{{cite news |last1=Rebecca Elliott |last2=Luis Santiago |title=A Decade in Which Fracking Rocked the Oil World |url=https://www.wsj.com/articles/a-decade-in-which-fracking-rocked-the-oil-world-11576630807 |access-date=20 December 2019 |work=[The Wall Street Journal](/source/The_Wall_Street_Journal) |date=17 December 2019 |quote=... hydraulic fracturing techniques spurred a historic U.S. production boom during the decade that has driven down consumer prices, buoyed the national economy and reshaped geopolitics.}}</ref><ref>{{Cite web|url=https://data.bloomberglp.com/professional/sites/24/2019-Sustainable-Energy-in-America-Factbook.pdf|title=2019 Sustainable Energy in America Factbook|website=Bloomberg New Energy Finance|access-date=28 April 2020}}</ref>

Fracking is highly controversial.<ref>{{Cite news|last=Urbina|first=Ian|title=Drilling Down|work=The New York Times|url=http://archive.nytimes.com/www.nytimes.com/interactive/us/DRILLING_DOWN_SERIES.html?_r=0}}</ref> Its proponents highlight the economic benefits of more extensively accessible [hydrocarbons](/source/hydrocarbons) (such as [petroleum](/source/petroleum) and [natural gas](/source/natural_gas)),<ref name="WEO2012 Special"/><ref>Hillard Huntington et al. [http://emf.stanford.edu/publications/emf_26_changing_the_game_emissions_and_market_implications_of_new_natural_gas_supplies/ EMF 26: Changing the Game? Emissions and Market Implications of New Natural Gas Supplies] {{Webarchive|url=https://web.archive.org/web/20201130192515/http://emf.stanford.edu/publications/emf_26_changing_the_game_emissions_and_market_implications_of_new_natural_gas_supplies/ |date=30 November 2020 }} Report. Stanford University. Energy Modeling Forum, 2013.</ref> the benefits of replacing [coal](/source/coal) with [natural gas](/source/natural_gas), which burns more cleanly and emits less [carbon dioxide](/source/carbon_dioxide) (CO<sub>2</sub>),<ref>{{cite news|url=https://www.bbc.co.uk/news/uk-14432401|title=What is fracking and why is it controversial?|work=[BBC News](/source/BBC_News)|date=15 October 2018}}</ref><ref>{{cite web|title=Cost and performance baseline for fossil energy plants, Volume 1: Bituminous coal and natural gas to electricity|url=http://www.netl.doe.gov/energy-analyses/pubs/BitBase_FinRep_Rev2.pdf|publisher=National Energy Technology Laboratory (NETL), [United States Department of Energy](/source/United_States_Department_of_Energy)|date=November 2010|access-date=15 August 2019|archive-date=24 January 2014|archive-url=https://web.archive.org/web/20140124181012/http://www.netl.doe.gov/energy-analyses/pubs/BitBase_FinRep_Rev2.pdf}}</ref> and the benefits of [energy independence](/source/energy_independence).<ref>{{Cite web |date=5 July 2017 |title=The Fracking Industry Deserves Our Gratitude |url=https://www.nationalreview.com/2017/07/fracking-industry-united-states-energy-independence-oil-middle-east-venezuela/ |access-date=26 October 2022 |website=National Review |language=en-US}}</ref> [Opponents of fracking](/source/anti-fracking_movement) argue that these are outweighed by the [environmental impacts](/source/Environmental_impact_of_hydraulic_fracturing), which include [groundwater](/source/groundwater) and [surface water](/source/surface_water) contamination,<ref>{{cite news|last=Fischetti|first=Mark|date=20 August 2013|title=Groundwater Contamination May End the Gas-Fracking Boom|volume=309|work=Scientific American|issue=3|url=https://www.scientificamerican.com/article/groundwater-contamination-may-end-the-gas-fracking-boom/}}</ref> [noise](/source/noise_pollution) and [air pollution](/source/air_pollution), the triggering of [earthquakes](/source/earthquakes), and the resulting hazards to public health and the environment.<ref name="HeatOnGas"/><ref name="EHP VJBrown" /> Research has found adverse health effects in populations living near hydraulic fracturing sites,<ref>{{cite journal |last1=Bamber |first1=AM |last2=Hasanali |first2=SH |last3=Nair |first3=AS |last4=Watkins |first4=SM |last5=Vigil |first5=DI |last6=Van Dyke |first6=M |last7=McMullin |first7=TS |last8=Richardson |first8=K |title=A Systematic Review of the Epidemiologic Literature Assessing Health Outcomes in Populations Living near Oil and Natural Gas Operations: Study Quality and Future Recommendations. |journal=International Journal of Environmental Research and Public Health |date=15 June 2019 |volume=16 |issue=12 |page=2123 |doi=10.3390/ijerph16122123 |pmid=31208070 |pmc=6616936|doi-access=free }}</ref><ref>{{cite journal |last1=Wright |first1=Rosemary |last2=Muma |first2=Richard D. |title=High-Volume Hydraulic Fracturing and Human Health Outcomes |journal=Journal of Occupational & Environmental Medicine |date=2018 |volume=60 |issue=5 |pages=424–429 |doi=10.1097/JOM.0000000000001278 |pmid=29370009 }}</ref> including confirmation of chemical, physical, and psychosocial hazards such as pregnancy and birth outcomes, migraine headaches, chronic [rhinosinusitis](/source/rhinosinusitis), severe fatigue, asthma exacerbations and psychological stress.<ref>{{cite book |last1=Gorski |first1=Irena |last2=Schwartz |first2=Brian S. |title=Oxford Research Encyclopedia of Global Public Health |chapter=Environmental Health Concerns from Unconventional Natural Gas Development |date=2019 |doi=10.1093/acrefore/9780190632366.013.44 |isbn=978-0-19-063236-6 }}</ref> Adherence to regulation and safety procedures are required to avoid further negative impacts.<ref>{{cite journal |last1=Costa |first1=D |last2=Jesus |first2=J |last3=Branco |first3=D |last4=Danko |first4=A |last5=Fiúza |first5=A |title=Extensive review of shale gas environmental impacts from scientific literature (2010-2015). |journal=Environmental Science and Pollution Research International |date=June 2017 |volume=24 |issue=17 |pages=14579–14594 |doi=10.1007/s11356-017-8970-0 |pmid=28452035 |bibcode=2017ESPR...2414579C }}</ref>
thumb|A graphic created to argue that modern-era fracking poses no risk of groundwater contamination.
The scale of [methane leakage](/source/methane_leakage) associated with hydraulic fracking is uncertain, and there is some evidence that leakage may cancel out any greenhouse gas emissions benefit of natural gas relative to other [fossil fuels](/source/fossil_fuels).<ref>{{Cite web |last=Storrow |first=Benjamin |date=2020-05-05 |title=Methane Leaks Erase Some of the Climate Benefits of Natural Gas |url=https://www.scientificamerican.com/article/methane-leaks-erase-some-of-the-climate-benefits-of-natural-gas/ |access-date=2023-09-12 |website=[Scientific American](/source/Scientific_American) |language=en}}</ref><ref>{{Cite journal |last1=Zhang |first1=Yuzhong |last2=Gautam |first2=Ritesh |last3=Pandey |first3=Sudhanshu |date=2020-04-23 |title=Quantifying methane emissions from the largest oil producing basin in the U.S. from space - Methane Emissions from the Permian Basin |url=https://legacy-assets.eenews.net/open_files/assets/2020/04/23/document_ew_03.pdf |journal=[Science Advances](/source/Science_Advances)}}</ref>

Increases in [seismic activity](/source/seismic_activity) following hydraulic fracking along dormant or previously unknown [faults](/source/fault_(geology)) are sometimes caused by the deep-injection disposal of fracking flowback fluid (a byproduct of hydraulically fracked wells),<ref name="Kim" /> and produced formation brine (a byproduct of both fractured and non-fractured oil and gas wells).<ref>US Geological Survey, [https://energy.usgs.gov/EnvironmentalAspects/EnvironmentalAspectsofEnergyProductionandUse/ProducedWaters.aspx#3822110-overview Produced water, overview], accessed 8 November 2014.</ref> For these reasons, hydraulic fracturing is under international scrutiny, restricted in some countries, and banned altogether in others.<ref name="interpress08072013" /><ref name="Bweek 31.03.2011" /><ref name="Bweek 04.10.2011" /> The European Union is drafting regulations that would permit the controlled application of hydraulic fracturing.<ref name="recommendation" />

==Geology==
{{main|Fracture (geology)}}

===Mechanics===
Fracturing rocks at great depth frequently become suppressed by [pressure](/source/pressure) due to the weight of the overlying rock strata and the cementation of the formation. This suppression process is particularly significant in "tensile" ([Mode 1](/source/Fracture)) fractures which require the walls of the fracture to move against this pressure. Fracturing occurs when [effective stress](/source/effective_stress) is overcome by the pressure of fluids within the rock. The minimum [principal stress](/source/principal_stress) becomes tensile and exceeds the [tensile strength](/source/tensile_strength) of the material.<ref name="Fjaer" /><ref name = "Price" /> Fractures formed in this way are generally oriented in a plane perpendicular to the minimum principal stress, and for this reason, hydraulic fractures in [wellbore](/source/wellbore)s can be used to determine the orientation of stresses.<ref name="Manthei"/> In natural examples, such as dikes or vein-filled fractures, the orientations can be used to infer past states of [stress](/source/Stress_(mechanics)).<ref name="Zoback"/>

===Veins===
Most mineral [vein](/source/vein_(geology)) systems are a result of repeated natural fracturing during periods of relatively high [pore fluid pressure](/source/pore_fluid_pressure). The effect of high pore fluid pressure on the formation process of mineral vein systems is particularly evident in "crack-seal" veins, where the vein material is part of a series of discrete fracturing events, and extra vein material is deposited on each occasion.<ref name="Laubach"/> One example of long-term repeated natural fracturing is in the effects of seismic activity. Stress levels rise and fall episodically, and earthquakes can cause large volumes of [connate](/source/Connate_fluids) water to be expelled from fluid-filled fractures. This process is referred to as "seismic pumping".<ref name="Sibson"/>

===Dikes===
Minor intrusions in the upper part of the [crust](/source/crust_(geology)), such as dikes, propagate in the form of fluid-filled cracks. In such cases, the fluid is [magma](/source/magma). In sedimentary rocks with a significant water content, fluid at fracture tip will be steam.<ref name="Gill"/>

== History ==
=== Precursors ===
[[File:Halliburton Frack Job in the Bakken.JPG|thumb|Halliburton fracturing operation in the [Bakken Formation](/source/Bakken_Formation), [North Dakota](/source/North_Dakota), United States]]
alt=Lightning Torpedo Company and nitroglycerin truck.|thumb|Lightning Torpedo Company

Fracking as a method to stimulate shallow, hard rock oil wells dates back to the 1860s, though the general concept of using water pressure to destroy rock was known as early as ancient Rome, in the form of [ruina montium](/source/ruina_montium). Dynamite or nitroglycerin detonations were used to increase oil and natural gas production from petroleum bearing formations. On 24 April 1865, [US Civil War](/source/US_Civil_War) veteran Col. Edward A. L. Roberts received a patent for an "[exploding torpedo](/source/Torpedo_(petroleum))".<ref name="shooters" /> It was employed in [Pennsylvania](/source/Pennsylvania), [New York](/source/New_York_(state)), [Kentucky](/source/Kentucky), [Oklahoma](/source/Oklahoma), [Texas](/source/Texas), and [West Virginia](/source/West_Virginia) using liquid and also, later, solidified [nitroglycerin](/source/nitroglycerin). Companies like [Lightning Torpedo Company](/source/Lightning_Torpedo_Company) used this process in Oklahoma and Texas. Later still the same method was applied to water and gas wells. Stimulation of wells with acid, instead of explosive fluids, was introduced in the 1930s. Due to [acid etching](/source/chemical_milling), fractures would not close completely, resulting in further productivity increase.<ref name="petrowiki" />

=== 20th century applications ===
[Harold Hamm](/source/Harold_Hamm), [Aubrey McClendon](/source/Aubrey_McClendon), [Tom Ward](/source/Tom_L._Ward) and [George P. Mitchell](/source/George_P._Mitchell) are each considered to have pioneered hydraulic fracking innovations toward practical applications.<ref>[https://mises.org/library/government-roads-subsidies-and-costs-fracking Khan, Salmaan A.] "Government Roads, Subsidies, and the Costs of Fracking", Mises Institute, 19 June 2014. Retrieved 20 February 2018.</ref><ref>[https://marcellusdrilling.com/2016/07/fracking-legend-harold-hamm-next-secretary-of-energy/ ''Marcellus''] "Fracking Legend Harold Hamm – Next Secretary of Energy?", Marcellus Drilling News, 22 June 2016. Retrieved 20 February 2018.</ref>

=== Oil and gas wells ===
The relationship between well performance and treatment pressures was studied by Floyd Farris of [Stanolind Oil and Gas Corporation](/source/Stanolind_Oil_and_Gas_Corporation). This study was the basis of the first hydraulic fracturing experiment, conducted in 1947 at the [Hugoton gas field](/source/Hugoton_Natural_Gas_Area) in [Grant County](/source/Grant_County%2C_Kansas) of southwestern [Kansas](/source/Kansas) by Stanolind.<ref name="Charlez"/><ref name="Montgomery"/> For the well treatment, {{convert|1000|USgal}} of gelled gasoline (essentially [napalm](/source/napalm)) and sand from the [Arkansas River](/source/Arkansas_River) was injected into the gas-producing limestone formation at {{convert|2400|ft}}. The experiment was not very successful as the deliverability of the well did not change appreciably. The process was further described by J.B. Clark of Stanolind in his paper published in 1948. A patent on this process was issued in 1949 and an exclusive license was granted to the Halliburton Oil Well Cementing Company. On 17 March 1949, Halliburton performed the first two commercial hydraulic fracking treatments in [Stephens County, Oklahoma](/source/Stephens_County%2C_Oklahoma), and [Archer County, Texas](/source/Archer_County%2C_Texas).<ref name="Montgomery"/> Since then, hydraulic fracking has been used to stimulate approximately one million oil and gas wells<ref name="UT Study"/> in various geologic regimes with good success.

In contrast with large-scale hydraulic fracturing used in low-permeability formations, small hydraulic fracturing treatments are commonly used in high-permeability formations to remedy "skin damage", a low-permeability zone that sometimes forms at the rock-borehole interface. In such cases the fracturing may extend only a few feet from the borehole.<ref>{{cite journal |last1=Settari |first1=A. |last2=Jones |first2=J.R. |last3=Stark |first3=A.J. |title=Analysis of Hydraulic Fracturing of High Permeability Gas Wells to Reduce Non-Darcy Skin Effects |journal=Journal of Canadian Petroleum Technology |date=2000 |volume=39 |issue=5 |article-number=PETSOC-00-05-04 |doi=10.2118/00-05-04 |bibcode=2000BCaPG..39.0504S }}</ref>

In the [Soviet Union](/source/Soviet_Union), the first hydraulic [proppant](/source/proppant) fracturing was carried out in 1952. 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.<ref name=Mader/>

=== Massive fracturing ===
thumb|upright|Well head where fluids are injected into the ground
thumb|Well head after all the hydraulic fracturing equipment has been taken off location

Massive hydraulic fracturing (also known as high-volume hydraulic fracturing) is a technique first applied by [Pan American Petroleum](/source/Pan_American_Petroleum) in [Stephens County, Oklahoma](/source/Stephens_County%2C_Oklahoma), US in 1968. 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.<ref name="Ben E 1993, p.233-252">Ben E. Law and Charles W. Spencer, 1993, "Gas in tight reservoirs-an emerging major source of energy", ''in'' David G. Howell (ed.), ''The Future of Energy Gasses'', US Geological Survey, Professional Paper 1570, pp. 233–252.</ref>

American geologists gradually became aware that there were huge volumes of gas-saturated sandstones with permeability too low (generally less than 0.1 [millidarcy](/source/millidarcy)) to recover the gas economically.<ref name="Ben E 1993, p.233-252"/> Starting in 1973, massive hydraulic fracturing was used in thousands of gas wells in the [San Juan Basin](/source/San_Juan_Basin), [Denver Basin](/source/Denver_Basin),<ref>C.R. Fast, G.B. Holman, and R. J. Covlin, "The application of massive hydraulic fracturing to the tight Muddy 'J' Formation, Wattenberg Field, Colorado", ''in'' Harry K. Veal, (ed.), ''Exploration Frontiers of the Central and Southern Rockies'' (Denver: [Rocky Mountain Association of Geologists](/source/Rocky_Mountain_Association_of_Geologists), 1977) 293–300.</ref> the [Piceance Basin](/source/Piceance_Basin),<ref>Robert Chancellor, "Mesaverde hydraulic fracture stimulation, northern Piceance Basin – progress report", ''in'' Harry K. Veal, (ed.), ''Exploration Frontiers of the Central and Southern Rockies'' (Denver: [Rocky Mountain Association of Geologists](/source/Rocky_Mountain_Association_of_Geologists), 1977) 285–291.</ref> and the [Green River Basin](/source/Green_River_Basin), and in other hard rock formations of the western US. Other tight sandstone wells in the US made economically viable by massive hydraulic fracturing were in the Clinton-Medina Sandstone (Ohio, Pennsylvania, and New York), and Cotton Valley Sandstone (Texas and Louisiana).<ref name="Ben E 1993, p.233-252"/>

Massive hydraulic fracturing quickly spread in the late 1970s to western Canada, [Rotliegend](/source/Rotliegend) and [Carboniferous](/source/Carboniferous) gas-bearing sandstones in Germany, Netherlands (onshore and offshore gas fields), and the United Kingdom in the [North Sea](/source/North_Sea).<ref name=Mader/>

[Horizontal oil or gas wells](/source/Horizontal_drilling) were unusual until the late 1980s. Then, operators in Texas began completing thousands of oil wells by drilling horizontally in the [Austin Chalk](/source/Austin_Chalk), and giving massive ''slickwater'' hydraulic fracturing treatments to the wellbores. Horizontal wells proved much more effective than vertical wells in producing oil from tight chalk;<ref>{{cite book |last1=Bell |first1=C. E. |last2=Holmes |first2=B. W. |last3=Rickards |first3=A. R. |title=SPE Annual Technical Conference and Exhibition |chapter=Effective Diverting on Horizontal Wells in the Austin Chalk |date=1993 |article-number=SPE-26582-MS |doi=10.2118/26582-MS }}</ref> sedimentary beds are usually nearly horizontal, so horizontal wells have much larger contact areas with the target formation.<ref name=Robbins2013/>

Hydraulic fracturing operations have grown exponentially since the mid-1990s, when technologic advances and increases in the price of natural gas made this technique economically viable.<ref name="McDermott-Levy 45–51">{{Cite journal|last1=McDermott-Levy|first1=Ruth|last2=Kaktins|first2=Nina|last3=Sattler|first3=Barbara|date=June 2013|title=Fracking, the Environment, and Health|journal=American Journal of Nursing|volume=113|issue=6|pages=45–51|doi=10.1097/01.naj.0000431272.83277.f4|pmid=23702766 }}</ref>

=== Shales ===
Hydraulic fracturing of shales goes back at least to 1965, when some operators in the Big Sandy gas field of eastern Kentucky and southern West Virginia started hydraulically fracturing the [Ohio Shale](/source/Ohio_Shale) and [Cleveland Shale](/source/Cleveland_Shale), using relatively small fracs. The frac jobs generally increased production, especially from lower-yielding wells.<ref>E. O. Ray, [http://www.netl.doe.gov/kmd/cds/disk7/disk1/EGS%5CDevonian%20Shale%20Development%20in%20Eastern%20Kentucky.pdf Shale development in eastern Kentucky] {{Webarchive|url=https://web.archive.org/web/20180324162207/https://www.netl.doe.gov/kmd/cds/disk7/disk1/EGS/Devonian |date=24 March 2018 }}, US Energy Research and Development Administration, 1976.</ref>

In 1976, the United States government started the [Eastern Gas Shales Project](/source/Eastern_Gas_Shales_Project), which included numerous public-private hydraulic fracturing demonstration projects.<ref>US Dept. of Energy, [http://energy.gov/sites/prod/files/2013/04/f0/how_is_shale_gas_produced.pdf How is shale gas produced?], April 2013.</ref> During the same period, the [Gas Research Institute](/source/Gas_Research_Institute), a gas industry research consortium, received approval for research and funding from the [Federal Energy Regulatory Commission](/source/Federal_Energy_Regulatory_Commission).<ref name="gri"/>

In 1997, Nick Steinsberger, an engineer of Mitchell Energy (now part of [Devon Energy](/source/Devon_Energy)), applied the slickwater fracturing technique, using more water and higher pump pressure than previous fracturing techniques, which was used in East Texas in the [Barnett Shale](/source/Barnett_Shale) of north Texas.<ref name=Robbins2013/> In 1998, the new technique proved to be successful when the first 90 days gas production from the well called S.H. Griffin No. 3 exceeded production of any of the company's previous wells.<ref name=gold>{{Cite book|title=The Boom: How Fracking Ignited the American Energy Revolution and Changed the World|last=Gold|first=Russell|publisher=Simon & Schuster|year=2014|isbn=978-1-4516-9228-0|location=New York|pages=115–121}}</ref><ref name=zukerman061113>{{Cite news | url = https://www.theatlantic.com/business/archive/2013/11/breakthrough-the-accidental-discovery-that-revolutionized-american-energy/281193/ | title = Breakthrough: The Accidental Discovery That Revolutionized American Energy | last = Zukerman | first = Gregory | work = The Atlantis | date = 6 November 2013 | access-date = 18 September 2016}}</ref> This new completion technique made gas extraction widely economical in the [Barnett Shale](/source/Barnett_Shale), and was later applied to other shales, including the [Eagle Ford](/source/Eagle_Ford) and [Bakken Shale](/source/Bakken_Shale).<ref name="AutoZV-10" /><ref name="SPE-20" /><ref name="AutoZV-9" /> [George P. Mitchell](/source/George_P._Mitchell) has been called the "father of fracking" because of his role in applying it in shales.<ref name=zukerman15112013>{{cite news | last = Zuckerman | first = Gregory | title = How fracking billionaires built their empires | url = http://qz.com/144435/how-fracking-billionaires-built-their-empires/ | work = Quartz|publisher=[The Atlantic Media Company](/source/The_Atlantic_Media_Company) | date = 15 November 2013 | access-date = 15 November 2013}}</ref> The first horizontal well in the [Barnett Shale](/source/Barnett_Shale) was drilled in 1991, but was not widely done in the Barnett until it was demonstrated that gas could be economically extracted from vertical wells in the Barnett.<ref name="Robbins2013">{{cite journal |last1=Robbins |first1=Kalyani |title=Awakening the Slumbering Giant: How Horizontal Drilling Technology Brought the Endangered Species Act to Bear on Hydraulic Fracturing |journal=Case Western Reserve L. Rev. |date=2013 |volume=63 |issue=4 |pages=1143–1166 |url=https://ecollections.law.fiu.edu/faculty_publications/257/ |id={{Gale|A334277570}} |ssrn=2262442 }}</ref>

As of 2013, massive hydraulic fracturing is being applied on a commercial scale to shales in the United States, Canada, and China. [Several additional countries are planning to use hydraulic fracturing](/source/Hydraulic_fracturing_by_country).<ref name=guardian010313/><ref name=nge070812/><ref name=reuters180213/>

== Process ==
{{for|further information on the reasons why fracking is carried out|Unconventional (oil & gas) reservoir#Essential differences between conventional and unconventional reservoirs}}
According to the [United States Environmental Protection Agency](/source/United_States_Environmental_Protection_Agency) (EPA), hydraulic fracturing is a process to stimulate a natural gas, oil, or geothermal well to maximize extraction. The EPA defines the broader process to include acquisition of source water, well construction, well stimulation, and waste disposal.<ref name="epa-ord" />

===Method===
A hydraulic fracture is formed by pumping [fracturing fluid](/source/fracturing_fluid) into a wellbore at a rate sufficient to increase pressure at the target depth (determined by the location of the well casing perforations), to exceed that of the fracture ''gradient'' (pressure gradient) of the rock.<ref name = "DOE primer"/> The fracture gradient is defined as pressure increase per unit of depth relative to density, and is usually measured in pounds per square inch, per foot (psi/ft). The rock cracks, and the fracture fluid permeates the rock extending the crack further, and further, and so on. Fractures are localized as pressure drops off with the rate of frictional loss, which is relative to the distance from the well. Operators typically try to maintain "fracture width", or slow its decline following treatment, by introducing a [proppant](/source/proppant) into the injected fluid{{spaced ndash}}a material such as grains of sand, ceramic, or other particulate, thus preventing the fractures from closing when injection is stopped and pressure removed. Consideration of proppant strength and prevention of proppant failure becomes more important at greater depths where pressure and stresses on fractures are higher. The propped fracture is permeable enough to allow the flow of gas, oil, salt water and hydraulic fracturing fluids to the well.<ref name="DOE primer" />

During the process, fracturing fluid leakoff (loss of fracturing fluid from the fracture channel into the surrounding permeable rock) occurs. If not controlled, it can exceed 70% of the injected volume. This may result in formation matrix damage, adverse formation fluid interaction, and altered fracture geometry, thereby decreasing efficiency.<ref name="Penny" />

The location of one or more fractures along the length of the borehole is strictly controlled by various methods that create or seal holes in the side of the wellbore. Hydraulic fracturing is performed in [cased](/source/Casing_(borehole)) wellbores, and the zones to be fractured are accessed by [perforating](/source/Perforation_(oil_well)) the casing at those locations.<ref name="Arthur"/>

Hydraulic-fracturing equipment used in oil and natural gas fields usually consists of a slurry blender, one or more high-pressure, high-volume fracturing pumps (typically powerful triplex or quintuplex pumps) and a monitoring unit. Associated equipment includes fracturing tanks, one or more units for storage and handling of proppant, high-pressure treating iron{{clarify|date=August 2014}}, a chemical additive unit (used to accurately monitor chemical addition), [fracking hose](/source/fracking_hose) (low-pressure flexible hoses), and many gauges and meters for flow rate, fluid density, and treating pressure.<ref name="Chilingar"/> Chemical additives are typically 0.5% of the total fluid volume. Fracturing equipment operates over a range of pressures and injection rates, and can reach up to {{convert|100|MPa|psi}} and {{convert|265|L/s|cuft/s USbbl/min}}.<ref name="Love"/>

===Well types===
A distinction can be made between conventional, low-volume hydraulic fracturing, used to stimulate high-permeability reservoirs for a single well, and unconventional, high-volume hydraulic fracturing, used in the completion of tight gas and shale gas wells. High-volume hydraulic fracturing usually requires higher pressures than low-volume fracturing; the higher pressures are needed to push out larger volumes of fluid and proppant that extend farther from the borehole.<ref name="bmp"/>

[Horizontal drilling](/source/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. For example, laterals extend {{convert|1500|to|5000|ft}} in the [Barnett Shale](/source/Barnett_Shale) basin in Texas, and up to {{convert|10000|ft}} in the [Bakken formation](/source/Bakken_formation) in North Dakota. In contrast, a vertical well only accesses the thickness of the rock layer, typically {{convert|50|-|300|ft}}. Horizontal drilling reduces surface disruptions as fewer wells are required to access the same volume of rock.

Drilling often plugs up the pore spaces at the wellbore wall, reducing permeability at and near the wellbore. This reduces flow into the borehole from the surrounding rock formation, and partially seals off the borehole from the surrounding rock. Low-volume hydraulic fracturing can be used to restore permeability.<ref name="Renpu"/>

===Fracturing fluids===
thumb|Water tanks preparing for hydraulic fracturing
{{Main|Hydraulic fracturing proppants|List of additives for hydraulic fracturing}}

The main purposes of fracturing fluid are to extend fractures, add lubrication, change gel strength, and to carry proppant into the formation. There are two methods of transporting proppant in the fluid{{spaced ndash}}high-rate and high-[viscosity](/source/viscosity). High-viscosity fracturing tends to cause large dominant fractures, while high-rate (slickwater) fracturing causes small spread-out micro-fractures.<ref name="Martín2016">{{cite book |last1=Martín |first1=Mariano |title=Alternative Energy Sources and Technologies |chapter=Nonconventional Fossil Energy Sources: Shale Gas and Methane Hydrates |date=2016 |pages=3–16 |doi=10.1007/978-3-319-28752-2_1 |isbn=978-3-319-28750-8 |quote=Two alternatives to transport the proppant can be used, either a high viscosity fluid or a high flow rate. The first one generates large fractures while the second one causes small micro fractures in the formation.}}</ref>

Water-soluble gelling agents (such as [guar gum](/source/guar_gum)) increase viscosity and efficiently deliver proppant into the formation.<ref name="CRO 2009"/>

thumb|Example of high pressure manifold combining pump flows before injection into well

Fluid is typically a [slurry](/source/slurry) of water, proppant, and [chemical additives](/source/List_of_additives_for_hydraulic_fracturing).<ref name=upenn/> Additionally, gels, foams, and compressed gases, including [nitrogen](/source/nitrogen), [carbon dioxide](/source/carbon_dioxide) and air can be injected. Typically, 90% of the fluid is water and 9.5% is sand with chemical additives accounting to about 0.5%.<ref name="DOE primer"/><ref name="Hartnett"/><ref name="freeing"/> However, fracturing fluids have been developed using [liquefied petroleum gas](/source/liquefied_petroleum_gas) (LPG) and propane. This process is called [waterless fracturing](/source/waterless_fracturing).<ref name=energyfuture>{{cite news |url=https://www.popsci.com/announcements/article/2013-05/june-2013-american-energy-independence |last=Brainard |first=Curtis |title=The Future of Energy |work=Popular Science Magazine |date=June 2013 |page=59 |access-date=1 January 2014}}</ref>

When propane is used it is turned into vapor by the high pressure and high temperature. The propane vapor and natural gas both return to the surface and can be collected, making it{{Clarify|date=July 2022}} easier to reuse and/or resale. None of the chemicals used will return to the surface. Only the propane used will return from what was used in the process.<ref>{{Cite web|last1=Brino|first1=Anthony|last2=Nearing|first2=Brian|date=6 November 2011|title=New Waterless Fracking Method Avoids Pollution Problems, But Drillers Slow to Embrace It|url=https://insideclimatenews.org/news/06112011/gasfrac-propane-natural-gas-drilling-hydraulic-fracturing-fracking-drinking-water-marcellus-shale-new-york/|access-date=17 November 2021|website=Inside Climate News|language=en-US}}</ref>

The proppant is a granular material that prevents the created fractures from closing after the fracturing treatment. Types of proppant include [silica sand](/source/silica_sand), resin-coated sand, [bauxite](/source/bauxite), and man-made ceramics. The choice of proppant depends on the type of permeability or grain strength needed. In some formations, where the pressure is great enough to crush grains of natural silica sand, higher-strength proppants such as bauxite or ceramics may be used. The most commonly used proppant is silica sand, though proppants of uniform size and shape, such as a ceramic proppant, are believed to be more effective.<ref name="AutoZV-12"/>

[[File:2011-2014 water use for fracking.jpg|thumb|USGS map of water use from hydraulic fracturing between 2011 and 2014. One cubic meter of water is 264.172 gallons.<ref>{{cite web | url=https://www.usgs.gov/newsroom/images/2015_06_30/water_use_for_fracking.jpg | title=Hydraulic fracturing water use, 2011–2014 | publisher=USGS | work=News images | access-date=3 July 2015 | archive-date=3 July 2015 | archive-url=https://web.archive.org/web/20150703170928/http://www.usgs.gov/newsroom/images/2015_06_30/water_use_for_fracking.jpg }}</ref><ref>{{cite web|title = Water Use Rises as Fracking Expands|url = https://www.scientificamerican.com/article/water-use-rises-as-fracking-expands/|access-date = 3 July 2015|first = Bobby|last = Central|website = [Scientific American](/source/Scientific_American)}}</ref>]]

The fracturing fluid varies depending on fracturing type desired, and the conditions of specific wells being fractured, and water characteristics. The fluid can be gel, foam, or slickwater-based. Fluid choices are tradeoffs: more viscous fluids, such as gels, are better at keeping proppant in suspension; while less-viscous and lower-friction fluids, such as slickwater, allow fluid to be pumped at higher rates, to create fractures farther out from the wellbore. Important material properties of the fluid include [viscosity](/source/viscosity), [pH](/source/pH), various [rheological factors](/source/rheology), and others.

Water is mixed with sand and chemicals to create hydraulic fracturing fluid. Approximately 40,000 gallons of chemicals are used per fracturing.<ref>{{cite web | access-date=27 April 2015 | archive-date=3 July 2015 | archive-url=https://web.archive.org/web/20150703142441/http://www.dangersoffracking.com/ | first1=Linda | last1=Dong | url=http://www.dangersoffracking.com | title=What goes in and out of Hydraulic Fracturing | website=Dangers of Fracking}}</ref>
A typical fracture treatment uses between 3 and 12 additive chemicals.<ref name="DOE primer"/> Although there may be unconventional fracturing fluids, typical chemical additives can include one or more of the following:
* [Acid](/source/Acid)s—[hydrochloric acid](/source/hydrochloric_acid) or [acetic acid](/source/acetic_acid) is used in the pre-fracturing stage for cleaning the perforations and initiating fissure in the near-wellbore rock.<ref name="freeing"/>
* [Sodium chloride](/source/Sodium_chloride) (salt)—delays breakdown of gel [polymer chain](/source/polymer_chain)s.<ref name="freeing"/>
* [Polyacrylamide](/source/Polyacrylamide) and other friction reducers decrease turbulence in fluid flow and pipe friction, thus allowing the pumps to pump at a higher rate without having greater pressure on the surface.<ref name="freeing"/>
* [Ethylene glycol](/source/Ethylene_glycol)—prevents formation of [scale deposits](/source/Fouling) in the pipe.<ref name="freeing"/>
* [Borate salts](/source/Borate_salts)—used for maintaining fluid viscosity during the temperature increase.<ref name="freeing"/>
* [Sodium](/source/Sodium_carbonate) and [potassium](/source/Potassium_carbonate) carbonates—used for maintaining effectiveness of [crosslinkers](/source/Cross-link).<ref name="freeing"/>
* [Glutaraldehyde](/source/Glutaraldehyde)- a [biocide](/source/biocide) that prevents pipe corrosion from microbial activity.<ref>{{cite press release |last1=Manning |first1=Anne |title=Hydraulic fracturing chemical spills on agricultural land need scrutiny, say CSU researchers |url=https://source.colostate.edu/hydraulic-fracturing-chemical-spills-on-agricultural-land-need-scrutiny-say-csu-researchers/ |publisher=Colorado State University |date=1 June 2016 }}</ref>
* [Guar gum](/source/Guar_gum) and other water-soluble gelling agents—increases viscosity of the fracturing fluid to deliver proppant into the formation more efficiently.<ref name="CRO 2009"/><ref name="freeing"/>
* [Citric acid](/source/Citric_acid)—used for [corrosion](/source/corrosion) prevention.
* [Isopropanol](/source/Isopropanol)—used to winterize the chemicals to ensure it doesn't freeze.<ref name="freeing"/>

The most common chemical used for [hydraulic fracturing in the United States](/source/hydraulic_fracturing_in_the_United_States) in 2005–2009 was [methanol](/source/methanol), while some other most widely used chemicals were [isopropyl alcohol](/source/isopropyl_alcohol), [2-butoxyethanol](/source/2-butoxyethanol), and [ethylene glycol](/source/ethylene_glycol).<ref name="house1"/>

Typical fluid types are:
* Conventional linear gels. These gels are cellulose derivative ([carboxymethyl cellulose](/source/carboxymethyl_cellulose), [hydroxyethyl cellulose](/source/hydroxyethyl_cellulose), [carboxymethyl hydroxyethyl cellulose](/source/carboxymethyl_hydroxyethyl_cellulose), [hydroxypropyl cellulose](/source/hydroxypropyl_cellulose), [hydroxyethyl methyl cellulose](/source/hydroxyethyl_methyl_cellulose)), [guar](/source/guar) or its derivatives ([hydroxypropyl guar](/source/hydroxypropyl_guar), [carboxymethyl hydroxypropyl guar](/source/carboxymethyl_hydroxypropyl_guar)), mixed with other chemicals.{{Clarify|date = November 2015|reason = How is this list supposed to be parsed?}}
* Borate-crosslinked fluids. These are guar-based fluids cross-linked with [boron](/source/boron) ions (from aqueous [borax](/source/borax)/[boric acid](/source/boric_acid) solution). These gels have higher viscosity at pH 9 onwards and are used to carry proppant. After the fracturing job, the pH is reduced to 3–4 so that the cross-links are broken, and the gel is less viscous and can be pumped out.
* Organometallic-crosslinked fluids – [zirconium](/source/zirconium), [chromium](/source/chromium), [antimony](/source/antimony), [titanium](/source/titanium) salts – are known to crosslink guar-based gels. The crosslinking mechanism is not reversible, so once the proppant is pumped down along with cross-linked gel, the fracturing part is done. The gels are broken down with appropriate breakers.{{clarify|date=August 2014}}<ref name="CRO 2009" />
* Aluminium phosphate-ester oil gels. [Aluminium phosphate](/source/Aluminium_phosphate) and [ester](/source/ester) oils are slurried to form cross-linked gel. These are one of the first known gelling systems.

For slickwater fluids the use of sweeps is common. Sweeps are temporary reductions in the proppant concentration, which help ensure that the well is not overwhelmed with proppant.<ref name="Canada"/> As the fracturing process proceeds, viscosity-reducing agents such as [oxidizer](/source/oxidizer)s and [enzyme](/source/enzyme) breakers are sometimes added to the fracturing fluid to deactivate the gelling agents and encourage flowback.<ref name="CRO 2009"/> Such oxidizers react with and break down the gel, reducing the fluid's viscosity and ensuring that no proppant is pulled from the formation. An enzyme acts as a catalyst for breaking down the gel. Sometimes [pH modifiers](/source/Froth_flotation) are used to break down the crosslink at the end of a hydraulic fracturing job, since many require a pH buffer system to stay viscous.<ref name="Canada"/> At the end of the job, the well is commonly flushed with water under pressure (sometimes blended with a friction reducing chemical.) Some (but not all) injected fluid is recovered. This fluid is managed by several methods, including underground injection control, treatment, discharge, recycling, and temporary storage in pits or containers. New technology is continually developing to better handle waste water and improve re-usability.<ref name="DOE primer"/>

===Fracture monitoring===
Measurements of the pressure and rate during the growth of a hydraulic fracture, with knowledge of fluid properties and proppant being injected into the well, provides the most common and simplest method of monitoring a hydraulic fracture treatment. This data along with knowledge of the underground geology can be used to model information such as length, width and conductivity of a propped fracture.<ref name="DOE primer"/>

==== Radionuclide monitoring ====
{{Main|Hydraulic fracturing and radionuclides}}

Injection of [radioactive tracer](/source/radioactive_tracer)s along with the fracturing fluid is sometimes used to determine the injection profile and location of created fractures.<ref name="Reis iodine" /> [Radiotracers](/source/radioactive_tracer) 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.<ref name="IAEA 2003" /> Radioactive isotopes chemically bonded to glass (sand) and/or resin beads may also be injected to track fractures.<ref name="NRC" /> For example, plastic pellets coated with 10 GBq of Ag-110mm may be added to the proppant, or sand may be labelled with Ir-192, so that the proppant's progress can be monitored.<ref name="IAEA 2003" /> Radiotracers such as Tc-99m and I-131 are also used to measure flow rates.<ref name="IAEA 2003" /> The [Nuclear Regulatory Commission](/source/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.<ref name="NRC" />

A new technique in well-monitoring involves fiber-optic cables outside the casing. Using the fiber optics, temperatures can be measured every foot along the well – even while the wells are being fracked and pumped. By monitoring the temperature of the well, engineers can determine how much hydraulic fracturing fluid different parts of the well use as well as how much natural gas or oil they collect, during hydraulic fracturing operation and when the well is producing.{{Citation needed|date=November 2015}}

==== Microseismic monitoring ====
For more advanced applications, [microseismic](/source/microseismic) monitoring is sometimes used to estimate the size and orientation of induced fractures. Microseismic activity is measured by placing an array of [geophone](/source/geophone)s in a nearby wellbore. By mapping the location of any small seismic events associated with the growing fracture, the approximate geometry of the fracture is inferred. [Tiltmeter](/source/Tiltmeter) arrays deployed on the surface or down a well provide another technology for monitoring strain<ref name="Oilfield Review 2005/2006"/>

Microseismic mapping is very similar geophysically to [seismology](/source/seismology). In earthquake seismology, seismometers scattered on or near the surface of the earth record [S-waves](/source/S-waves) and [P-waves](/source/P-waves) that are released during an earthquake event. This allows for motion{{clarify|date=August 2014}} along the fault plane to be estimated and its location in the Earth's subsurface mapped. Hydraulic fracturing, an increase in formation stress proportional to the net fracturing pressure, as well as an increase in pore pressure due to leakoff.{{clarify|reason = Not only is this highly technical, it's not a sentence.|date=November 2015}}<ref name="Fehler 1989">{{cite journal |last=Fehler |first=Michael C. |title=Stress Control of seismicity patterns observed during hydraulic fracturing experiments at the Fenton Hill hot dry rock geothermal energy site, New Mexico |journal=International Journal of Rock Mechanics and Mining Sciences & Geomechanics Abstracts |year= 1989 |volume= 26 |issue=3–4 |series=3 |doi=10.1016/0148-9062(89)91971-2 |pages=211–219 |bibcode=1989IJRMA..26..211F |osti=6545065 |url=https://zenodo.org/record/1258335 }}</ref> Tensile stresses are generated ahead of the fracture's tip, generating large amounts of [shear stress](/source/shear_stress). The increases in [pore water pressure](/source/pore_water_pressure) and in formation stress combine and affect weaknesses near the hydraulic fracture, like natural fractures, joints, and bedding planes.<ref name="Le Calvez 2007">{{cite book |last1=Le Calvez |first1=J. H. |last2=Klem |first2=R. C. |last3=Bennett |first3=L. |last4=Erwemi |first4=A. |last5=Craven |first5=M. |last6=Palacio |first6=J. C. |title=SPE Hydraulic Fracturing Technology Conference |chapter=Real-Time Microseismic Monitoring of Hydraulic Fracture Treatment: A Tool to Improve Completion and Reservoir Management |date=2007 |article-number=SPE-106159-MS |doi=10.2118/106159-MS }}</ref>

Different methods have different location errors{{clarify|date=August 2014}} and advantages. Accuracy of microseismic event mapping is dependent on the signal-to-noise ratio and the distribution of sensors. Accuracy of events located by [seismic inversion](/source/seismic_inversion) is improved by sensors placed in multiple azimuths from the monitored borehole. In a downhole array location, accuracy of events is improved by being close to the monitored borehole (high signal-to-noise ratio).

Monitoring of microseismic events induced by reservoir{{clarify|date=August 2014}} stimulation has become a key aspect in evaluation of hydraulic fractures, and their optimization. The main goal of hydraulic fracture monitoring is to completely characterize the induced fracture structure, and distribution of conductivity within a formation. 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.<ref name="Cipolla 2010">{{cite book |last1=Cipolla |first1=C. L. |last2=Williams |first2=M. J. |last3=Weng |first3=X. |last4=Mack |first4=M. |last5=Maxwell |first5=S. |title=SPE Annual Technical Conference and Exhibition |chapter=Hydraulic Fracture Monitoring to Reservoir Simulation: Maximizing Value |date=2010 |article-number=SPE-133877-MS |doi=10.2118/133877-MS }}</ref> The next task is to know the location of proppant within the fracture and the distribution of fracture conductivity. This can be monitored using multiple types of techniques to finally develop a reservoir model that accurately predicts well performance.

===Horizontal completions===
Since the early 2000s, advances in [drilling](/source/Oil_well) and [completion](/source/Completion_(oil_and_gas_wells)) technology have made horizontal wellbores much{{clarify|date=August 2014}} more economical. Horizontal wellbores allow far greater exposure to a formation than conventional vertical wellbores. This is particularly useful in shale formations which do not have sufficient permeability to produce economically with a vertical well. Such wells, when drilled onshore, are now usually hydraulically fractured in a number of stages, especially in North America. The type of wellbore completion is used to determine how many times a formation is fractured, and at what locations along the horizontal section.<ref name="AutoZV-13" />

In North America, shale reservoirs such as the [Bakken](/source/Bakken_formation), [Barnett](/source/Barnett_Shale), [Montney](/source/Montney_Formation), [Haynesville](/source/Haynesville_Shale), [Marcellus](/source/Marcellus_Formation), and most recently the [Eagle Ford](/source/Eagle_Ford_Formation), [Niobrara](/source/Niobrara_Formation) and [Utica](/source/Utica_Shale) shales are drilled horizontally through the producing intervals, completed and fractured.{{Citation needed |date=December 2011}} The method by which the fractures are placed along the wellbore is most commonly achieved by one of two methods, known as "plug and perf" and "sliding sleeve".<ref name="undeerc"/>

The wellbore for a plug-and-perf job is generally composed of standard steel casing, cemented or uncemented, set in the drilled hole. Once the drilling rig has been removed, a [wireline truck](/source/Wireline_(cabling)) is used to [perforate](/source/Perforation_(oil_well)) near the bottom of the well, and then fracturing fluid is pumped. Then the wireline truck sets a plug in the well to temporarily seal off that section so the next section of the wellbore can be treated. Another stage is pumped, and the process is repeated along the horizontal length of the wellbore.<ref name="AutoZV-14" />

The wellbore for the sliding sleeve{{clarify|date=August 2014}} technique is different in that the sliding sleeves are included at set spacings in the steel casing at the time it is set in place. The sliding sleeves are usually all closed at this time. When the well is due to be fractured, the bottom sliding sleeve is opened using one of several activation techniques{{Citation needed |date=August 2015}} and the first stage gets pumped. Once finished, the next sleeve is opened, concurrently isolating the previous stage, and the process repeats. For the sliding sleeve method, wireline is usually not required.{{Citation needed|date=December 2011}}

thumb|Sleeves

These completion techniques may allow for more than 30 stages to be pumped into the horizontal section of a single well if required, which is far more than would typically be pumped into a vertical well that had far fewer feet of producing zone exposed.<ref name = "mooney" />

== Uses ==
Hydraulic fracturing is used to increase the rate at which substances such as petroleum or natural gas can be recovered from subterranean natural reservoirs. Reservoirs are typically porous [sandstone](/source/sandstone)s, [limestone](/source/limestone)s or [dolomite](/source/Dolomite_(rock)) rocks, but also include "[unconventional reservoirs](/source/Unconventional_(oil_%26_gas)_reservoir)" such as [shale](/source/shale) rock or [coal](/source/coal) beds. Hydraulic fracturing enables the extraction of natural gas and oil from rock formations deep below the earth's surface (generally {{convert|5000|–|20000|ft|m|abbr=on|order=flip|sigfig=1}}), which is greatly below typical groundwater reservoir levels. At such depth, there may be insufficient [permeability](/source/Permeability_(earth_sciences)) or reservoir pressure to allow natural gas and oil to flow from the rock into the wellbore at high economic return. Thus, creating conductive fractures in the rock is instrumental in extraction from naturally impermeable shale reservoirs. Permeability is measured in the micro[darcy](/source/darcy_(unit)) to nanodarcy range.<ref name="AutoZV-2" /> Fractures are a conductive path connecting a larger volume of reservoir to the well. So-called "super fracking" creates cracks deeper in the rock formation to release more oil and gas, and increases efficiency.<ref name="BW 19.01.2012"/> The yield for typical shale bores generally falls off after the first year or two, but the peak producing life of a well can be extended to several decades.<ref name="Geosoc yield" />

===Non-oil/gas uses===
While the main industrial use of hydraulic fracturing is in stimulating production from oil and gas wells,<ref name="Economides"/><ref name="AutoZV-3"/><ref name="AutoZV-4"/> hydraulic fracturing is also applied:
* To stimulate groundwater wells<ref name="AutoZV-6" />
* To precondition or induce rock cave-ins [mining](/source/mining)<ref name="AutoZV-7" />
* As a means of enhancing waste remediation, usually hydrocarbon waste or spills<ref name = "hazmat40.2" />
* To dispose waste by injection deep into rock<ref name="Bell" />
* To measure stress in the Earth<ref name="Aamodt" />
* For electricity generation in [enhanced geothermal system](/source/enhanced_geothermal_system)s<ref name="AutoZV-8" />
* To increase injection rates for [geologic sequestration of {{CO2}}](/source/Geologic_sequestration_of_CO2)<ref name="Miller" />
* To store electrical energy, [pumped storage hydroelectricity](/source/pumped_storage_hydroelectricity)<ref name="TM91221">{{cite news |author1=Russell Gold |title=Fracking Has a Bad Rep, but Its Tech Is Powering a Clean Energy Shift Texas start-ups are harnessing know-how born of the shale boom in pursuit of a greener future. |access-date=23 September 2021 |work=Texas Monthly |date=21 September 2021|url=https://www.texasmonthly.com/news-politics/fracking-clean-energy-geothermal/}}</ref>

Since the late 1970s, hydraulic fracturing has been used, in some cases, to increase the yield of drinking water from wells in a number of countries, including the United States, Australia, and South Africa.<ref>{{Citation |id={{INIST|PASCALGEODEBRGM8320302315}} | first1 = James | last1 = Waltz | first2 = Tim L | last2 = Decker | title = Hydro-fracturing offers many benefits | journal = Johnson Driller's Journal | issue = 2nd quarter | year = 1981 | pages = 4–9}}</ref><ref>{{Citation | first = WH | last = Williamson | contribution = The use of hydraulic techniques to improve the yield of bores in fractured rocks | title = Groundwater in Fractured Rock | publisher = Australian Water Resources Council | series = Conference Series | number = 5 | year = 1982}}</ref><ref>{{Citation | first1 = C | last1 = Less | first2 = N | last2 = Andersen | title = Hydrofracture: state of the art in South Africa | journal = Applied Hydrogeology | date=Feb 1994 | volume = 2 | issue = 2 | pages = 59–63| doi = 10.1007/s100400050050 | bibcode = 1994HydJ....2...59L }}</ref>

==Economic effects==
{{see also|Shale gas|Tight oil|Price of oil|Hydraulic fracturing in the United States}}Hydraulic fracturing has been seen as one of the key methods of extracting [unconventional oil](/source/unconventional_oil) and [unconventional gas](/source/unconventional_gas) resources. According to the [International Energy Agency](/source/International_Energy_Agency), the remaining technically recoverable resources of shale gas are estimated to amount to {{convert|208|e12m3|e12cuft|abbr=off}}, tight gas to {{convert|76|e12m3|e12cuft|abbr=off}}, and [coalbed methane](/source/coalbed_methane) to {{convert|47|e12m3|e12cuft|abbr=off}}. As a rule, formations of these resources have lower permeability than conventional gas formations. Therefore, depending on the geological characteristics of the formation, specific technologies such as hydraulic fracturing are required. Although there are also other methods to extract these resources, such as conventional drilling or horizontal drilling, hydraulic fracturing is one of the key methods making their extraction economically viable. 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.<ref name="WEO2012 Special"/>

A large majority of studies indicate that hydraulic fracturing in the United States has had a strong positive economic benefit so far.{{citation needed|date=December 2020}} The Brookings Institution estimates that the benefits of Shale Gas alone has led to a net economic benefit of $48 billion per year. Most of this benefit is within the consumer and industrial sectors due to the significantly reduced prices for natural gas.<ref>{{Cite news|url=https://www.brookings.edu/blog/brookings-now/2015/03/23/the-economic-benefits-of-fracking/|title=The economic benefits of fracking|last=Dews|first=Fred|work=Brookings|access-date=21 November 2017}}</ref> Other studies have suggested that the economic benefits are outweighed by the externalities and that the [levelized cost of electricity](/source/levelized_cost_of_electricity) (LCOE) from less carbon- and water-intensive sources is lower.<ref>Phillips. K. (2012). What is the True Cost of Hydraulic Fracturing? Incorporating Negative Externalities into the Cost of America's Latest Energy Alternative. ''Journal of Environmental Sciences Program''. 2,1st Edition, Appalachian State University, Boone, NC</ref>

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.<ref>{{cite journal |last1=Kilian |first1=Lutz |title=The Impact of the Fracking Boom on Arab Oil Producers |journal=The Energy Journal |date=2017 |volume=38 |issue=6 |pages=137–160 |doi=10.5547/01956574.38.6.lkil |bibcode=2017EnerJ..38..137K |hdl=10419/128457 |hdl-access=free }}</ref> However, shale oil and gas is highly subsidised in the US, and has not yet covered production costs<ref>{{cite news|title=Wall Street Tells Frackers to Stop Counting Barrels, Start Making Profits|url=https://www.wsj.com/articles/wall-streets-fracking-frenzy-runs-dry-as-profits-fail-to-materialize-1512577420|newspaper=The Wall Street Journal|date=13 December 2017|access-date=2 May 2018|last1=Lynn Cook|first1=Bradley Olson and}}</ref> – meaning that the cost of hydraulic fracturing is paid for in income taxes, and in many cases is up to double the cost paid at the pump.<ref>{{cite web|last1=Berman|first1=Art|title=Shale Gas Is Not A Revolution|url=https://www.forbes.com/sites/arthurberman/2017/07/05/shale-gas-is-not-a-revolution/|work=Forbes|access-date=2 May 2018}}</ref>

Research suggests that hydraulic fracturing wells have an adverse effect on agricultural productivity in the vicinity of the wells.<ref name=":0">{{Cite conference |url=http://pubdocs.worldbank.org/en/512621474052605239/1A-3-Naima-Farah.pdf |archive-url=https://web.archive.org/web/20161029111627/http://pubdocs.worldbank.org/en/512621474052605239/1A-3-Naima-Farah.pdf |archive-date=2016-10-29 |title=Fracking and Land Productivity: Effects of Hydraulic Fracturing on Agriculture |website=World Bank |author=Naima Farah|date=September 2016|pages=1–9|conference=Annual Meeting of the International Water and Resource Economics Consortium}}</ref> 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. This effect becomes smaller and weaker as the distance between township and wells increases."<ref name=":0" /> The findings imply that the introduction of hydraulic fracturing wells to Alberta cost the province $14.8 million in 2014 due to the decline in the crop productivity,<ref name=":0" />

The Energy Information Administration of the US Department of Energy estimates that 45% of US gas supply will come from shale gas by 2035 (with the vast majority of this replacing conventional gas, which has a lower greenhouse-gas footprint).<ref>{{cite journal |last1=Howarth |first1=Robert W. |last2=Ingraffea |first2=Anthony |last3=Engelder |first3=Terry |title=Should fracking stop? |journal=Nature |date=2011 |volume=477 |issue=7364 |pages=271–275 |doi=10.1038/477271a |pmid=21921896 }}</ref>

==Public debate==
[[File:Vitoria - fracking ez.jpg|thumb|Poster in [Basque](/source/Basque_language) against hydraulic fracturing in [Vitoria-Gasteiz](/source/Vitoria-Gasteiz) ([Basque Country](/source/Basque_Country_(greater_region)), Spain, 2012)]]
[[File:Frack off, Extinction Rebellion (cropped).jpg|thumb|Placard against hydraulic fracturing at [Extinction Rebellion](/source/Extinction_Rebellion) (2018)]]

===Politics and public policy===

====Popular movement and civil society organizations====
An [anti-fracking movement](/source/anti-fracking_movement) has emerged both internationally with involvement of international [environmental organization](/source/environmental_organization)s and nations such as France and locally in affected areas such as [Balcombe](/source/Balcombe) in Sussex where the [Balcombe drilling protest](/source/Balcombe_drilling_protest) was in progress during mid-2013.<ref name=Ecologist713>{{cite news|title=The UK's anti fracking movement is growing |url=http://www.theecologist.org/News/news_analysis/2016997/the_uks_anti_fracking_movement_is_growing.html |access-date=29 July 2013 |work=The Ecologist|date=1 August 2013|author=Jan Goodey}}</ref> The considerable opposition against hydraulic fracturing activities in local townships in the United States has led companies to adopt a variety of [public relations](/source/public_relations) measures to reassure the public, including the employment of former military personnel with training in [psychological warfare](/source/psychological_warfare) operations. According to Matt Pitzarella, the communications director at [Range Resources](/source/Range_Resources), employees trained in the Middle East have been valuable to Range Resources in Pennsylvania, when dealing with emotionally charged township meetings and advising townships on zoning and local ordinances dealing with hydraulic fracturing.<ref name="psyops"/><ref name="AutoZV-38"/>

There have been many protests directed at hydraulic fracturing. 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.<ref name="PalmerMike"/> In northwest Pennsylvania, there was a drive-by shooting at a well site, in which someone shot two rounds of a small-caliber rifle in the direction of a drilling rig.<ref name="PhillyInq001"/> In [Washington County, Pennsylvania](/source/Washington_County%2C_Pennsylvania), a contractor working on a gas pipeline found a [pipe bomb](/source/pipe_bomb) that had been placed where a pipeline was to be constructed, which local authorities said would have caused a "catastrophe" had they not discovered and detonated it.<ref name="DetrowScott"/>

====U.S. government and corporate lobbying====
The [United States Department of State](/source/United_States_Department_of_State) established the Global Shale Gas Initiative to persuade governments around the world to give concessions to [the major oil and gas companies](/source/Big_Oil) to set up fracking operations. A document from the [United States diplomatic cables leak](/source/United_States_diplomatic_cables_leak) show that, as part of this project, U.S. officials convened conferences for foreign government officials that featured presentations by major oil and gas company representatives and by [public relations](/source/public_relations) professionals with expertise on how to assuage populations of target countries whose citizens were often quite hostile to fracking on their lands. The US government project succeeded as many countries on several continents acceded to the idea of granting concessions for fracking; [Poland](/source/Poland), for example, agreed to permit fracking by the major oil and gas corporations on nearly a third of its territory.<ref>{{cite news |last1=Blake |first1=Mariah |title=How Hillary Clinton's State Department sold fracking to the world |url=https://www.motherjones.com/politics/2014/09/hillary-clinton-fracking-shale-state-department-chevron/ |work=Mother Jones }}</ref> The [US Export-Import Bank](/source/US_Export-Import_Bank), an agency of the US government, provided $4.7 billion in financing for fracking operations set up since 2010 in [Queensland, Australia](/source/Queensland%2C_Australia).<ref>{{cite news |last1=Burke |first1=Jason |last2=Slezak |first2=Michael |last3=Milman |first3=Oliver |title=Obama's dirty secret: the fossil fuel projects the US littered around the world |url=https://www.theguardian.com/environment/2016/dec/01/obama-fossil-fuels-us-export-import-bank-energy-projects |work=The Guardian |date=1 December 2016 }}</ref>

====Alleged Russian state advocacy====
In 2014 a number of European officials suggested that several major European protests against hydraulic fracturing (with mixed success in Lithuania and Ukraine) may be partially sponsored by [Gazprom](/source/Gazprom), Russia's state-controlled gas company. ''[The New York Times](/source/The_New_York_Times)'' suggested that Russia saw its natural gas exports to Europe as a key element of its geopolitical influence, and that this market would diminish if hydraulic fracturing is adopted in Eastern Europe, as it opens up significant [shale gas](/source/shale_gas) reserves in the region. Russian officials have on numerous occasions made public statements to the effect that hydraulic fracturing "poses a huge environmental problem".<ref>{{cite news | url=https://www.nytimes.com/2014/12/01/world/russian-money-suspected-behind-fracking-protests.html | title=Russian Money Suspected Behind Fracking Protests | work=The New York Times | date=30 November 2014 | access-date=4 December 2014 | author=Andrew Higgins}}</ref>

====Current fracking operations====
Hydraulic fracturing is currently taking place in the United States in Arkansas, California, Colorado, Louisiana, North Dakota, Oklahoma, Pennsylvania, Texas, Virginia, West Virginia,<ref>{{cite web |last1=Uhle |first1=Amanda |title=He Said I Was a Fracking Heiress. I Went to West Virginia to Find Out. |url=https://www.politico.com/news/magazine/2023/05/28/fracking-economy-appalachia-00060086 |website=Politico |date=28 May 2023 |access-date=30 May 2023}}</ref> and Wyoming. As of 2024,  there are currently seven major fracking operations active in the United States.<ref name=":2">{{Cite web |title=Drilling Productivity Report - U.S. Energy Information Administration (EIA) |url=https://www.eia.gov/petroleum/drilling/ |archive-url=https://web.archive.org/web/20250929113730/https://www.eia.gov/petroleum/drilling/ |archive-date=29 September 2025 |access-date=2025-12-04 |website=www.eia.gov |url-status=live }}</ref> These are the Bakken operation in North Dakota and Montane, Niobrara operation in Wyoming and Colorado, Anandarko in Northern Texas and Oklahoma, Permian and Eagle Ford in Texas, Haynesville in Texas and Louisiana, and the large Appalachia site.<ref name=":2" /> California has had a longtime moratorium on fracking and Vermont, New York, Maryland, Washington, and Oregon all have statewide fracking bans.<ref>{{Cite web |last=Staff |first=Climate XChange |date=2024-08-09 |title=Policy Explainer: Fracking Bans |url=https://climate-xchange.org/2024/08/policy-explainer-drilling-down-on-state-efforts-to-ban-fracking/ |access-date=2025-12-04 |website=Climate XChange}}</ref>

Although a hydraulic fracturing moratorium was recently lifted in the United Kingdom, the government is proceeding cautiously because of concerns about earthquakes and the environmental effect of drilling. Hydraulic fracturing is currently banned in France and Bulgaria.<ref name="McDermott-Levy 45–51" />

===Documentary films===
[Josh Fox](/source/Josh_Fox)'s [2010 Academy Award](/source/83rd_Academy_Awards) nominated film ''[Gasland](/source/Gasland)''<ref>{{IMDb title|tt1558250|GasLand}}</ref> became a center of opposition to hydraulic fracturing of shale. The movie presented problems with groundwater contamination near well sites in [Pennsylvania](/source/Pennsylvania), [Wyoming](/source/Wyoming) and [Colorado](/source/Colorado).<ref name="AutoZV-25"/> ''Energy in Depth'', an oil and gas industry lobbying group, called the film's facts into question.<ref name=indepth/> In response, a rebuttal of ''<nowiki>Energy in Depth'</nowiki>''s claims of inaccuracy was posted on ''Gasland's'' website.<ref name="AutoZV-27"/> The Director of the [Colorado Oil and Gas Conservation Commission](/source/Colorado_Department_of_Natural_Resources) (COGCC) offered to be interviewed as part of the film if he could review what was included from the interview in the final film but Fox declined the offer.<ref name=COGCC/> [ExxonMobil](/source/ExxonMobil), [Chevron Corporation](/source/Chevron_Corporation) and [ConocoPhillips](/source/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.<ref name="Promised Land" />

The 2012 film ''[Promised Land](/source/Promised_Land_(2012_film))'', starring [Matt Damon](/source/Matt_Damon), takes on hydraulic fracturing.<ref name=progressive/> The gas industry countered the film's criticisms of hydraulic fracturing with flyers, and [Twitter](/source/Twitter) and [Facebook](/source/Facebook) posts.<ref name="Promised Land" />

In January 2013, [Northern Irish](/source/Northern_Ireland) journalist and filmmaker [Phelim McAleer](/source/Phelim_McAleer) released a crowdfunded<ref>Kickstarter, FrackNation by Ann and Phelim Media LLC, 6 April 2012</ref> documentary called ''[FrackNation](/source/FrackNation)'' as a response to the statements made by Fox in ''Gasland'', claiming it "tells the truth about fracking for natural gas". ''FrackNation'' premiered on [Mark Cuban](/source/Mark_Cuban)'s [AXS TV](/source/AXS_TV). The premiere corresponded with the release of ''Promised Land''.<ref>{{cite news |last1=Bond |first1=Paul |title=Mark Cuban's AXS TV Picks Up Pro-Fracking Documentary 'FrackNation' |url=https://www.hollywoodreporter.com/news/general-news/fracknation-mark-cubans-axs-tv-402780/ |work=The Hollywood Reporter |date=17 December 2012 }}</ref>

In April 2013, Josh Fox released ''Gasland 2'', his "international odyssey uncovering a trail of secrets, lies and contamination related to hydraulic fracking". It challenges the gas industry's portrayal of natural gas as a clean and safe alternative to oil as a myth, and that hydraulically fractured wells inevitably leak over time, contaminating water and air, hurting families, and endangering the Earth's climate with the potent greenhouse gas methane.{{fact|date=January 2026}}

In 2014, Scott Cannon of Video Innovations released the documentary ''The Ethics of Fracking''. The film covers the politics, spiritual, scientific, medical and professional points of view on hydraulic fracturing. It also digs into the way the gas industry portrays hydraulic fracturing in their advertising.<ref>{{cite web|title=The Ethics of Fracking|url=http://www.greenplanetfilms.org/product/the-ethics-of-fracking/|website=Green Planet Films|access-date=27 April 2015|archive-date=1 October 2020|archive-url=https://web.archive.org/web/20201001122318/https://www.greenplanetfilms.org/product/the-ethics-of-fracking/}}</ref>

In 2015, the Canadian documentary film ''[Fractured Land](/source/Fractured_Land)'' had its world premiere at the [Hot Docs Canadian International Documentary Festival](/source/Hot_Docs_Canadian_International_Documentary_Festival).<ref>{{cite web |url=https://thetyee.ca/Video/2015/09/09/Fractured-Land-VIFF/ |work=The Tyee |date=9 September 2015 |title='Fractured Land' Doc Coming to VIFF |access-date=20 October 2015}}</ref>

===Research issues===
Typically the funding source of the research studies is a focal point of controversy. Concerns have been raised about research funded by foundations and corporations, or by environmental groups, which can at times lead to at least the appearance of unreliable studies.<ref name="Deller"/><ref name="SoraghanMike"/> Several organizations, researchers, and media outlets have reported difficulty in conducting and reporting the results of studies on hydraulic fracturing due to industry<ref name="Urbina 03Mar2011" /> and governmental pressure,<ref name="interpress08072013" /> and expressed concern over possible censoring of environmental reports.<ref name = "Urbina 03Mar2011" /><ref name="NYT lobbying docs" /><ref name="NYT Docs" /> Some have argued there is a need for more research into the environmental and health effects of the technique.<ref name=fh2013>{{cite journal | last1 = Finkel | first1 = M.L. | last2 = Hays | first2 = J. |title=The implications of unconventional drilling for natural gas: a global public health concern |journal=Public Health |volume=127 |issue=10 |pages=889–893 | date=October 2013 |pmid=24119661 |doi=10.1016/j.puhe.2013.07.005 |type=Review}}</ref>{{sfn|Kibble|Cabianca|Daraktchieva|Gooding|2014|p={{pn|date=January 2026}}}}<ref name="Bloomberg 11.01.2012" /><ref name="BW 04Jan2012" />

==Health risks==
thumb|Anti-fracking banner at the Clean Energy March (Philadelphia, 2016)

There is concern over the possible adverse [public health](/source/public_health) implications of hydraulic fracturing activity.<ref name=fh2013/> A 2013 review on shale gas production in the United States stated, "with increasing numbers of drilling sites, more people are at risk from accidents and exposure to harmful substances used at fractured wells."<ref name=Centner2013>{{cite journal|last1=Centner|first1=Terence J.|title=Oversight of shale gas production in the United States and the disclosure of toxic substances|journal=Resources Policy|date=September 2013|volume=38|issue=3|pages=233–240 |doi=10.1016/j.resourpol.2013.03.001 |bibcode=2013RePol..38..233C }}</ref> A 2011 hazard assessment recommended full disclosure of chemicals used for hydraulic fracturing and drilling as many have immediate health effects, and many may have long-term health effects.<ref name=Colborn2011>{{cite journal |last1=Colborn |first1=Theo |last2=Kwiatkowski |first2=Carol |last3=Schultz |first3=Kim |last4=Bachran |first4=Mary |title=Natural Gas Operations from a Public Health Perspective |journal=Human and Ecological Risk Assessment: An International Journal |date=2011 |volume=17 |issue=5 |pages=1039–1056 |doi=10.1080/10807039.2011.605662 |bibcode=2011HERA...17.1039C }}</ref>

In June 2014 [Public Health England](/source/Public_Health_England) published a review of the potential public health impacts of exposures to chemical and radioactive pollutants as a result of shale gas extraction in the UK, based on the examination of literature and data from countries where hydraulic fracturing already occurs.{{sfn|Kibble|Cabianca|Daraktchieva|Gooding|2014|p={{pn|date=January 2026}}}} 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. Most evidence suggests that [contamination of groundwater](/source/Groundwater_pollution), if it occurs, is most likely to be caused by leakage through the vertical borehole. Contamination of groundwater from the underground hydraulic fracturing process itself (i.e. the fracturing of the shale) is unlikely. However, surface spills of hydraulic fracturing fluids or wastewater may affect groundwater, and emissions to air also have the potential to impact on health. Where potential risks have been identified in the literature, the reported problems are typically a result of operational failure and a poor regulatory environment."{{sfn|Kibble|Cabianca|Daraktchieva|Gooding|2014|p=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.<ref name=aea2012/> This led to a series of recommendations in 2014 to mitigate these concerns.<ref>{{cite web |title=EU Commission minimum principles for the exploration and production of hydrocarbons (such as shale gas) using high-volume hydraulic fracturing|url=http://eur-lex.europa.eu/legal-content/EN/TXT/?uri=CELEX:32014H0070|website=European Union |date=8 February 2014}}</ref><ref>{{cite web|title=Energy and environment|url=https://ec.europa.eu/environment/integration/energy/unconventional_en.htm|website=European Union|date=16 June 2023 }}</ref> A 2012 guidance for pediatric nurses in the US said that hydraulic fracturing had a potential negative impact on public health and that pediatric nurses should be prepared to gather information on such topics so as to advocate for improved community health.<ref name=lauver2012>{{cite journal |vauthors=Lauver LS |title=Environmental health advocacy: an overview of natural gas drilling in northeast Pennsylvania and implications for pediatric nursing |journal=J Pediatr Nurs |volume=27 |issue=4 |pages=383–9 | date=August 2012 |pmid=22703686 |doi=10.1016/j.pedn.2011.07.012 }}</ref>

A 2017 study in ''[The American Economic Review](/source/The_American_Economic_Review)'' found that "additional well pads drilled within 1 kilometer of a community water system intake increases shale gas-related contaminants in drinking water."<ref>{{cite journal |last1=Hill |first1=Elaine |last2=Ma |first2=Lala |title=Shale Gas Development and Drinking Water Quality |journal=American Economic Review |date=2017 |volume=107 |issue=5 |pages=522–525 |doi=10.1257/aer.p20171133 |pmid=29430021 |pmc=5804812 }}</ref>

A 2022 study conduced by Harvard T.H. Chan School of Public Health and published in Nature Energy found that elderly people living near or downwind of [unconventional oil and gas](/source/unconventional_oil_and_gas) development (UOGD) -- which involves extraction methods including fracking—are at greater risk of experiencing early death compared with elderly persons who don't live near such operations.<ref>{{cite journal |last1=Li |first1=Longxiang |last2=Dominici |first2=Francesca |last3=Blomberg |first3=Annelise J. |last4=Bargagli-Stoffi |first4=Falco J. |last5=Schwartz |first5=Joel D. |last6=Coull |first6=Brent A. |last7=Spengler |first7=John D. |last8=Wei |first8=Yaguang |last9=Lawrence |first9=Joy |last10=Koutrakis |first10=Petros |title=Exposure to unconventional oil and gas development and all-cause mortality in Medicare beneficiaries |journal=Nature Energy |date=2022 |volume=7 |issue=2 |pages=177–185 |doi=10.1038/s41560-021-00970-y |pmid=35425643 |pmc=9004666 |bibcode=2022NatEn...7..177L }}</ref>

Statistics collected by the U.S. Department of Labor and analyzed by the [U.S. Centers for Disease Control and Prevention](/source/Centers_for_Disease_Control_and_Prevention) show a correlation between drilling activity and the number of occupational injuries related to drilling and motor vehicle accidents, explosions, falls, and fires.<ref>{{Cite journal |date=2008|title=Fatalities among oil and gas extraction workers – United States, 2003–2006 |website=American Psychological Association |doi=10.1037/e458082008-002 }}</ref> 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).<ref>{{Cite journal|last1=McDonald|first1=J. C.|last2=McDonald|first2=A. D.|last3=Hughes|first3=J. M.|last4=Rando|first4=R. J.|last5=Weill|first5=H.|date=22 February 2005|title=Mortality from Lung and Kidney Disease in a Cohort of North American Industrial Sand Workers: An Update|journal=The Annals of Occupational Hygiene|volume=49|issue=5|pages=367–73|doi=10.1093/annhyg/mei001 |pmid=15728107|doi-access=free}}</ref> The U.S. National Institute for Occupational Safety and Health ([NIOSH](/source/National_Institute_for_Occupational_Safety_and_Health)) identified exposure to airborne silica as a health hazard to workers conducting some hydraulic fracturing operations.<ref name=":02">{{Cite web|url=https://www.cdc.gov/niosh/docs/2012-166/|title=OSHA/NIOSH Hazard Alert: Worker Exposure to Silica During Hydraulic Fracturing|date=June 2012}}</ref> NIOSH and OSHA issued a joint hazard alert on this topic in June 2012.<ref name=":02" />

Additionally, the extraction workforce is at increased risk for radiation exposure. Fracking activities often require drilling into rock that contains naturally occurring radioactive material (NORM), such as radon, thorium, and uranium.<ref name="dx.doi.org">{{Cite journal |date=1 June 1993|title=Office of radiation and indoor air: Program description |website=University of North Texas |doi=10.2172/10115876 |url=https://digital.library.unt.edu/ark:/67531/metadc1272587/|doi-access=free }}</ref>

Another report done by the Canadian Medical Journal reported that after researching they identified 55 factors that may cause cancer, including 20 that have been shown to increase the risk of leukemia and lymphoma. The Yale Public Health analysis warns that millions of people living within a mile of fracking wells may have been exposed to these chemicals.<ref>{{cite journal| pmc=5235941 | pmid=27956395 | doi=10.1503/cmaj.109-5358 | volume=189 | issue=2 | title=Fracking tied to cancer-causing chemicals | year=2017 | journal=CMAJ | pages=E94–E95 | last1 = Vogel | first1 = L}}</ref>

Despite these health concerns and efforts to institute a moratorium on fracking until its environmental and health effects are better understood, the United States continues to rely heavily on fossil fuel energy. In 2017, 37% of annual U.S. energy consumption is derived from petroleum, 29% from natural gas, 14% from coal, and 9% from nuclear sources, with only 11% supplied by renewable energy, such as wind and solar power.<ref name="EIA_2017">{{Cite web |last=U.S. Energy Information Administration |date=16 May 2018 |title=U.S. Energy Facts Explained |url=https://www.eia.gov/energyexplained/?page=us_energy_home}}</ref>

== Environmental justice ==
Fracking can cause many different environmental justice issues.<ref name="Clough Environmental justice">{{cite journal |last1=Clough |first1=Emily |title=Environmental justice and fracking: A review |journal=Current Opinion in Environmental Science & Health |date=2018 |volume=3 |pages=14–18 |doi=10.1016/j.coesh.2018.02.005 |bibcode=2018COESH...3...14C }}</ref> One of the main justice issues associated with fracking is the effect the wells have on the communities they are placed in.<ref name="Clough Environmental justice"/> A majority of the fracking sites in the United States are located in poor, rural areas.<ref name=":3">{{Cite journal |last=Castelli |first=Matthew |date=2015-05-08 |title=Fracking and the Rural Poor: Negative Externalities, Failing Remedies, and Federal Legislation |url=https://www.repository.law.indiana.edu/ijlse/vol3/iss2/6 |journal=Indiana Journal of Law and Social Equality |volume=3 |issue=2}}</ref> The locations of the wells result in the poor, people of color, and native peoples being disproportionately affected by the negative externalities of fracking operations.<ref name=":3" />

Many fracking companies claim their sites will result in more job opportunities for the communities they are located in. However, in an article interviewing the author of a report on Ohio fracking sites, the report author, Sean O'Leary stated "Completed wells don't need many permanent employees. And many people who work in drilling and fracking come outside the local area."<ref>{{Cite web |first1=Canary|last1=Media|first2=Kathiann M.|last2=Kowalski|date=2025-08-19 |title=In Appalachia, fracking is not the job creator the industry claims • Ohio Capital Journal |url=https://ohiocapitaljournal.com/2025/08/19/in-appalachia-fracking-is-not-the-job-creator-the-industry-claims/ |access-date=2025-12-04 |website=Ohio Capital Journal |language=en-US}}</ref> This becomes an issue because many of these fracking sites are built in poor, rural communities, where people need employment.<ref>{{cite news |last1=Bienkowski |first1=Brian |title=Poor Communities Bear Greatest Burden from Fracking |url=https://www.scientificamerican.com/article/poor-communities-bear-greatest-burden-from-fracking/ |work=Scientific American |date=6 May 2015 }}</ref> There have been many cases where there has been an observed decline in employment following fracking implementation. Since the Appalachian fracking boom in 2008, thirty large gas companies in Ohio, Pennsylvania, and West Virginia have logged a large economic output, but jobs in the area fell by 1% while nationally job opportunities rose 14%, employment grew 4% in the fracking regions while the nation employment rate grew by 10%, and income had grown three quarters the rate of the national average.<ref name="O'Leary Frackalachia Update 2025">{{cite news |last1=O'Leary |first1=Sean |title=Frackalachia Update 2025 |url=https://ohiorivervalleyinstitute.org/frackalachia-update-2025/ |work=Ohio River Valley Institute |date=31 July 2025 }}</ref>  According to Sean O'Leary,  a senior researcher at Ohio River Valley Institute, makes the point that "While some studies have found that economic conditions improve in areas where fracking is introduced, these studies fail to negate the fact that the negative externalities from fracking are centralized in these regions (poor rural regions)  and that they often burden those who do not receive economic benefits from fracking."<ref name="O'Leary Frackalachia Update 2025"/> Though many regions are promised economic benefits, typically in poor rural areas where this is needed, these benefits never come to fruition. One such case is prevalent in North Jackson Ohio, where a local, Mel Cadle allowed the construction of wells on his farm with the promise of lucrative royalties, but, as Cadle stated, "I don't have any income from these wells. I lost five acres for nothing," as a result of the oil companies making false promises and not providing him any sort of financial gain for the use of his land.<ref>{{Cite web |last=O'Brien |first=Dan |date=2021-08-31 |title=Utica Shale Pumped Up Promises to Valley Landowners |url=https://businessjournaldaily.com/article/utica-shale-pumped-up-promises/ |access-date=2025-12-04 |website=Business Journal Daily {{!}} The Youngstown Publishing Company |language=en-US}}</ref>
Native peoples also face a disproportionate amount of fracking in their communities, as companies and the government often take their land and destroy it for mineral resources such as gas and oil.<ref name="Palmer Exploring the Negative Impacts">{{cite news |last1=Palmer |first1=Shelley |title=Exploring the Negative Impacts of Fracking Policies on Native American Lands and Communities |url=https://theclassicjournal.org/exploring-the-negative-impacts-of-fracking/ |work=The Classic Journal }}</ref> According to the Classic Journal, legislation has been created in the United States to allow this to occur, specifically federal acts such as the Mineral Leasing Act of 1938 and the Indian Self- Determination and Education Assistance Act of 1975 that both restrict Natives' rights to resources on their lands.<ref name="Palmer Exploring the Negative Impacts"/> A major issue associated with fracking that oftentimes falls onto Native Tribes' is chemical filled wastewater from fracking sites.<ref name="Palmer Exploring the Negative Impacts"/> A study was conducted by Shelley Palmer and other University of Georgia faculty members exploring the negative impacts of fracking policies on Native American lands and communities states that "regulatory loopholes allow untreated wastewater from fracking to be disposed of onto Native American lands, resulting in pollution issues and human health hazards".<ref name="Palmer Exploring the Negative Impacts"/>

Some of the major environmental and health consequences associated with fracking result in rural communities where the wells are located to be disproportionately affected by water contamination, air contamination, and land contamination.<ref name=":3"/> Research conducted by law scholar Matthew Castell found that neither federal status nor common law provide affected communities and landowners with access to solutions or help for harms caused by fracking.<ref name=":3"/> Social science and environmental health researcher Vivian Underhill and Professor of sociology and environment and sustainability "found that from 2014 through 2024, 62% to 73% of reported fracks each year used at least one chemical that the Safe Drinking Water Act recognizes as detrimental to human health and the environment. If not for the Halliburton Loophole, these projects would have been subject to permitting and monitoring requirements, providing information for local communities about potential risks.<ref>{{Cite web |last1=Vera |first1=Lourdes |last2=Underhill |first2=Vivian R. |date=2023-04-03 |title=Companies that frack for oil and gas can keep a lot of information secret – but what they disclose shows widespread use of hazardous chemicals |url=http://theconversation.com/companies-that-frack-for-oil-and-gas-can-keep-a-lot-of-information-secret-but-what-they-disclose-shows-widespread-use-of-hazardous-chemicals-193915 |access-date=2025-12-04 |website=The Conversation |language=en-US}}</ref>

==Environmental impacts==
{{Main|Environmental impact of fracking}}

{{See also|Environmental impact of hydraulic fracturing in the United States|Exemptions for hydraulic fracturing under United States federal law}}
{{infobox industrial process
| name           = Environmental Effects of Hydraulic Fracturing
| image          = HydroFrac2.svg
| caption        = Schematic depiction of hydraulic fracturing for [shale gas](/source/shale_gas)
| type           = Mechanical
| sector         = [Mining](/source/Mining)
| technologies   = Fluid pressure
| feedstock      =
| product        = [Natural gas](/source/Natural_gas), [petroleum](/source/petroleum)
| companies      =
| facility       =
| inventor       = Floyd Farris, Joseph B. Clark ([Stanolind Oil and Gas Corporation](/source/Stanolind_Oil_and_Gas_Corporation))
| year           = 1947
| developer      =
}}<!--
PLEASE ADD NEW INFORMATION TO THE BODY OF THE MAIN [Environmental impact of hydraulic fracturing](/source/Environmental_impact_of_hydraulic_fracturing) ARTICLE. IF, IN THAT ARTICLE, IT IS IMPORTANT ENOUGH TO ADD TO THE LEAD OF THAT ARTICLE, PLEASE ADD IT TO THE LEAD OF THAT ARTICLE. ONLY IN THAT CASE, INCLUDE IT HERE. THE SECTION BELOW IS TAKEN FROM THE LEAD OF THAT ARTICLE PER [WP:SUMMARY](/source/WP%3ASUMMARY)
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[[File:ALICE-SPRINGS-20-SEPT-2019-STRIKE-00006 (48762501556).jpg|thumb|[September 2019 climate strike](/source/September_2019_climate_strikes) in Alice Springs, Australia]]
The potential environmental effects of hydraulic fracturing include air pollution and contribution climate change, high water consumption, groundwater contamination, land use,<ref>{{cite journal |last1=Hu |first1=Tongxi |last2=Toman |first2=Elizabeth |last3=Chen |first3=Gang |last4=Shao |first4=Gang |last5=Zhou |first5=Yuyu |title=Mapping fine-scale human disturbances in a working landscape with Landsat time series on Google Earth Engine |journal=ISPRS Journal of Photogrammetry and Remote Sensing |date=2021 |volume=176 |pages=250–261 |doi=10.1016/j.isprsjprs.2021.04.008 |bibcode=2021JPRS..176..250H }}</ref> induced earthquakes, noise pollution, and various health effects on humans.<ref>{{cite journal |last1=Tatomir |first1=Alexandru |last2=McDermott |first2=Christopher |last3=Bensabat |first3=Jacob |last4=Class |first4=Holger |last5=Edlmann |first5=Katriona |last6=Taherdangkoo |first6=Reza |last7=Sauter |first7=Martin |title=Conceptual model development using a generic Features, Events, and Processes (FEP) database for assessing the potential impact of hydraulic fracturing on groundwater aquifers |journal=Advances in Geosciences |date=2018 |volume=45 |pages=185–192 |doi=10.5194/adgeo-45-185-2018 |doi-access=free |bibcode=2018AdG....45..185T |hdl=20.500.11820/b83437b4-6791-4c4c-8f45-744a116c6ead |hdl-access=free }}</ref> 

=== Air contamination ===
Air emissions are primarily methane that escapes from wells, along with industrial emissions from equipment used in the extraction process.<ref name="aea2012" /> Modern UK and EU regulation requires zero emissions of methane, a potent [greenhouse gas](/source/greenhouse_gas).{{citation needed|date=July 2019}} Escape of methane is a bigger problem in older wells than in ones built under more recent EU legislation.<ref name="aea2012" />

=== Water use and contamination ===
In December 2016 the United States Environmental Protection Agency (EPA) issued the "Hydraulic Fracturing for Oil and Gas: Impacts from the Hydraulic Fracturing Water Cycle on Drinking Water Resources in the United States (Final Report)." The EPA found scientific evidence that hydraulic fracturing activities can impact drinking water resources.<ref name=":1">{{Cite web |title=EPA's Report on Fracking and Water Quality |url=https://online.law.tulane.edu/blog/epa-fracking-report-water-quality |access-date=2025-12-04 |website=Tulane |language=en}}</ref> A few of the main reasons why drinking water can be contaminated according to the EPA are:

* Water removal to be used for fracking in times or areas of low water availability<ref name=":1" />
* Spills while handling fracking fluids and chemicals that result in large volumes or high concentrations of chemicals reaching groundwater resources<ref name=":1" /> 
* Injection of fracking fluids into wells when mishandling machinery, allowing gases or liquids to move to groundwater resources<ref name=":1" /> 
* Injection of fracking fluids directly into groundwater resources<ref name=":1" /> 
* Leak of defective hydraulic fracturing wastewater to surface water<ref name=":1" /> 
* Disposal or storage of fracking wastewater in unlined pits resulting in contamination of groundwater resources.<ref name=":1" />

The lifecycle [greenhouse gas emissions](/source/greenhouse_gas_emissions) of [shale oil](/source/shale_oil) are 21%-47% higher than those of conventional oil, while emissions from [unconventional gas](/source/unconventional_gas) are from 6% lower to 43% higher than the emissions of conventional gas.<ref>{{cite web |title=Unconventional Fossil Fuels Factsheet |url=https://css.umich.edu/publications/factsheets/energy/unconventional-fossil-fuels-factsheet |website=Center for Sustainable Systems |publisher=University of Michigan |access-date=1 December 2023}}</ref>

Hydraulic fracturing uses between {{convert|1.2|and|3.5|e6USgal|m3}} of water per well, with large projects using up to {{convert|5|e6USgal|m3}}.<ref>{{cite book |last1=Buono |first1=Regina |last2=Lopez-Gunn |first2=Elena |last3=McKay |first3=Jennifer |last4=Staddon |first4=Chad |title=Regulating Water Security in Unconventional Oil and Gas |date=2020|publisher=Springer Cham|isbn=978-3-030-18342-4 |edition=1st 2020}}</ref> Additional water is used when wells are refractured.<ref name="CRO 2009"/><ref name="Penn State Water"/> An average well requires {{convert |3|to|8|e6USgal|m3}} of water over its lifetime.<ref name="DOE primer"/> According to the [Oxford Institute for Energy Studies](/source/Oxford_Institute_for_Energy_Studies), greater volumes of fracturing fluids are required in Europe, where the shale depths average 1.5 times greater than in the U.S.<ref name="shale Europe"/> [Surface water](/source/Surface_water) may be contaminated through spillage and improperly built and maintained waste pits,<ref name="Surface Spills"/> and [ground water](/source/ground_water) can be contaminated if the fluid is able to escape the formation being fractured (through, for example, [abandoned wells](/source/abandoned_wells), fractures, and faults<ref>{{cite journal |last1=Taherdangkoo |first1=Reza |last2=Tatomir |first2=Alexandru |last3=Taylor |first3=Robert |last4=Sauter |first4=Martin |title=Numerical investigations of upward migration of fracking fluid along a fault zone during and after stimulation |journal=Energy Procedia |date=September 2017 |volume=125 |pages=126–135 |doi=10.1016/j.egypro.2017.08.093 |doi-access=free |bibcode=2017EnPro.125..126T }}</ref>) or by [produced water](/source/produced_water) (the returning fluids, which also contain dissolved constituents such as minerals and [brine water](/source/brine_water)s). The possibility of groundwater contamination from brine and fracturing fluid leakage through old abandoned wells is low.<ref>{{cite journal |last1=Taherdangkoo |first1=Reza |last2=Tatomir |first2=Alexandru |last3=Anighoro |first3=Tega |last4=Sauter |first4=Martin |title=Modeling fate and transport of hydraulic fracturing fluid in the presence of abandoned wells |journal=Journal of Contaminant Hydrology |date=February 2019 |volume=221 |pages=58–68 |doi=10.1016/j.jconhyd.2018.12.003 |pmid=30679092 |bibcode=2019JCHyd.221...58T }}</ref>{{sfn|Kibble|Cabianca|Daraktchieva|Gooding|2014|p={{pn|date=January 2026}}}} Produced water is managed by [underground injection](/source/Injection_well), [municipal](/source/sewage_treatment) and [commercial](/source/industrial_wastewater_treatment) [wastewater treatment](/source/wastewater_treatment) and discharge, self-contained systems at well sites or fields, and recycling to fracture future wells.<ref name="LoganJeffrey" /> Typically less than half of the produced water used to fracture the formation is recovered.<ref>{{cite web|last1=Köster|first1=Vera|title=What is Shale Gas? How Does Fracking Work?| url = http://www.chemistryviews.org/details/education/1316813/What_is_Shale_Gas_How_Does_Fracking_Work.html|website=www.chemistryviews.org|date=5 February 2013 |access-date=4 December 2014}}</ref>

Fracking causes many different types of pollution, including water pollution. After the well is fracked and produces oil and gas, fracking fluids often remain underground, where it may contaminate groundwater and connect to aquifer systems.<ref name=":4">{{Cite web |title=Hydraulic Fracturing and its Impact on Water Resources |url=https://watercalculator.org/footprint/fracking-water/ |access-date=2025-12-04 |website=Water Footprint Calculator |language=en-US}}</ref> The wastewater produced from the operations is also toxic and must be stored correctly, treated, and then discharged, but it is often stored in holding ponds that can leak into the surrounding ground and impact wildlife.<ref name=":4"/> Federal and state responses to the impacted water resources have been mixed at best, {{clarify span|according to…. According to … Federally,|date=December 2025}} "regulation is insufficient due to certain explicit exemptions from the Safe Drinking Water Act, the Clean Air Act, and the Clean Water Act granted by the Energy Policy Act of 2005.” <ref name=":4" /> 

People obtain drinking water from either surface water, which includes rivers and reservoirs, or groundwater aquifers, accessed by public or private wells. There are 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.<ref>{{Cite journal |last1=Osborn |first1=Stephen G. |last2=Vengosh |first2=Avner |last3=Warner |first3=Nathaniel R. |last4=Jackson |first4=Robert B. |date=2011-05-17 |title=Methane contamination of drinking water accompanying gas-well drilling and hydraulic fracturing |journal=Proceedings of the National Academy of Sciences of the United States of America |volume=108 |issue=20 |pages=8172–8176 |doi=10.1073/pnas.1100682108 |doi-access=free |pmc=3100993 |pmid=21555547 |bibcode=2011PNAS..108.8172O }}</ref><ref>{{cite book |title=Who's Who |chapter=Roberts, Dr John Esmond, (Born 29 June 1951), Deputy Director (Part time), Common Agricultural Policy Direct Payments, Department for Environment, Food and Rural Affairs, 2011–15; Secretary, Royal Commission on Environmental Pollution, 2009–11 |date=2008 |doi=10.1093/ww/9780199540884.013.u246698 }}</ref>

[Per- and polyfluoroalkyl substances](/source/Per-_and_polyfluoroalkyl_substances) also known as "PFAS" or "forever chemicals" have been linked to cancer and birth defects. The chemicals used in fracking stay in the environment. Once there those chemicals will eventually break down into PFAS. These chemicals can escape from drilling sites and into the groundwater. PFAS are able to leak into underground wells that store million gallons of wastewater.<ref>{{Cite news |last=Tabuchi |first=Hiroko |author-link=Hiroko Tabuchi |date=13 July 2021 |title=E.P.A. Allowed Fracking Chemicals Despite Worries |url=https://www.nytimes.com/2021/07/12/climate/epa-pfas-fracking-forever-chemicals.html |access-date=20 October 2021 |newspaper=The New York Times |page=B1 |id={{Gale|A668271858}}}}</ref> 

In addition to water contamination, fracking uses a substantial amount of water. One well can use anywhere from 1.5 million to 16 million gallons of water.<ref>{{Cite web |title=Hydraulic Fracturing Water Usage {{!}} Ground Water Protection Council |url=https://www.gwpc.org/topics/hydraulic-fracturing/hydraulic-fracturing-water-usage/ |access-date=2025-12-04 |language=en-US}}</ref> There is concern about the impact of fracking on local water resources, especially in the drier regions of the United States.<ref>{{Cite web |date=2021-09-23 |title=How much water does the typical hydraulically fractured well require? {{!}} U.S. Geological Survey |url=https://www.usgs.gov/faqs/how-much-water-does-typical-hydraulically-fractured-well-require |access-date=2025-12-04 |website=www.usgs.gov |language=en}}</ref> These fracking sites are consuming millions of gallons of water from aquifers that are already dwindling.<ref>{{cite news |last1=Kightlinger |first1=Diana |title=Fracking Is Draining US Groundwater at an Alarming Rate |url=https://www.idexxcurrents.com/en/latest/fracking-is-draining-us-groundwater-at-an-alarming-rate/ |work=Currents |publisher=IDEXX |date=1 March 2024 }}</ref> According to the New York Times,  "Nationwide, fracking has used up nearly 1.5 trillion gallons of water since 2011. That's how much tap water the entire state of Texas uses in a year."<ref>{{Cite news |last1=Tabuchi |first1=Hiroko |last2=Migliozzi |first2=Blacki |date=2023-09-25 |title='Monster Fracks' Are Getting Far Bigger. And Far Thirstier. |url=https://www.nytimes.com/interactive/2023/09/25/climate/fracking-oil-gas-wells-water.html |access-date=2025-12-04 |work=The New York Times }}</ref> 

=== Land use ===
In the United States over {{convert|12|e6acres}} are being used for fossil fuels. This is equivalent of six Yellowstone National Parks.<ref>{{cite web |title=7 ways oil and gas drilling is bad for the environment |url=https://www.wilderness.org/articles/blog/7-ways-oil-and-gas-drilling-bad-environment |work=The Wilderness Society }}{{rs|date=January 2026}}</ref> About {{convert|3.6|ha}} of land is needed per each [drill pad](/source/drill_pad) for surface installations. Well pad and supporting structure construction significantly fragments landscapes which likely has negative effects on wildlife.<ref>{{cite journal|title=Habitat Loss and Modification Due to Gas Development in the Fayetteville Shale |date=8 January 2015 |doi=10.1007/s00267-014-0440-6 |pmid=25566834 |volume=55 |issue = 6|journal=Environmental Management |pages=1276–1284 | last1 = Moran | first1 = Matthew D. |bibcode=2015EnMan..55.1276M }}</ref> These sites need to be remediated after wells are exhausted.<ref name=aea2012/> Research indicates that effects on [ecosystem service](/source/ecosystem_service)s costs (i.e., those processes that the natural world provides to humanity) has reached over $250 million per year in the U.S.<ref>{{cite journal|doi=10.1002/fee.1492 | volume=15 | issue=5 | title=Land-use and ecosystem services costs of unconventional US oil and gas development | journal=Frontiers in Ecology and the Environment | pages=237–242 | last1 = Moran | first1 = Matthew D | year=2017| bibcode=2017FrEE...15..237M }}</ref> Each well pad (in average 10 wells per pad) needs during preparatory and hydraulic fracturing process about 800 to 2,500 days of noisy activity, which affect both residents and local wildlife. In addition, noise is created by continuous truck traffic (sand, etc.) needed in hydraulic fracturing.<ref name=aea2012/> Research is underway to determine if human health has been affected by [air](/source/Air_pollution) and [water pollution](/source/water_pollution), and rigorous following of safety procedures and regulation is required to avoid harm and to manage the risk of accidents that could cause harm.{{sfn|Kibble|Cabianca|Daraktchieva|Gooding|2014|p={{pn|date=January 2026}}}}

In July 2013, the US Federal Railroad Administration listed oil contamination by hydraulic fracturing chemicals as "a possible cause" of corrosion in oil tank cars.<ref>Frederick J. Herrmann, Federal Railroad Administration, [https://railroads.dot.gov/elibrary/letter-american-petroleum-institute letter to American Petroleum Institute], 17 July 2013, p.4.</ref>

=== Induced seismic activity ===

Hydraulic fracturing has been tied to induced seismicity or earthquakes in regions where few or no earthquakes were previously recorded.<ref name=":5">{{Cite web |date=2018-05-31 |title=Does fracking cause earthquakes? {{!}} U.S. Geological Survey |url=https://www.usgs.gov/faqs/does-fracking-cause-earthquakes |access-date=2025-12-04 |website=www.usgs.gov |language=en}}</ref> Fracking has been the major catalyst for at least 2% of earthquakes in the United States according to the United States Geological Survey, but could be higher.<ref name=":5" /> Geologists have known since the 1960s that pushing fluids into the ground, as done during fracking, can set off earthquakes, but the USGS has argued that this was ignored by many fossil-fuel companies.<ref name=":6">{{Cite web |last1=Kuchment |first1=-Anna |last2=Kuchment |first2=Scientific American Anna |date=2016-03-28 |title=Drilling-induced earthquakes may endanger millions in 2016, USGS says |url=https://www.pbs.org/newshour/science/drilling-induced-earthquakes-may-endanger-millions-in-2016-usgs-says |access-date=2025-12-04 |website=PBS News |language=en-us}}</ref> The connection was first recognized when a well was drilled outside a plant in Denver, and more than 700 small to modest size earthquakes ensued, corresponding with the volume and pressure of the injections into the well.<ref name=":6" />  Behind a large increase in these earthquakes are wastewater injection wells, in which wells are drilled horizontally and is used in many fracking operations.<ref name=":6" /> A U.S. Geological Survey reported that up to 7.9 million people in several states have a similar earthquake risk to that of California, with hydraulic fracturing and similar practices being a prime contributing factor.<ref>{{cite book |last1=Fenton |first1=Clark |last2=Gray |first2=Mark |last3=Hyland |first3=Natalie |last4=Smith |first4=James |title=IAEG/AEG Annual Meeting Proceedings, San Francisco, California, 2018 - Volume 5 |chapter=Fault-Landslide Interactions: Examples from the 2016 M7.8 'Kaikōura', New Zealand, Earthquake |date=2019 |pages=33–41 |doi=10.1007/978-3-319-93136-4_5 |isbn=978-3-319-93135-7 }}</ref>

Texas and Oklahoma have been two of the regions impacted most by fracking induced seismic activity. Prior to 2008, not a single earthquake had been recorded in the Dallas- Fort Worth region of Texas, but since then the region has been experiencing a sixfold increase in earthquakes.<ref>{{Cite web |last1=Kuchment |first1=-Anna |last2=Kuchment |first2=Scientific American Anna |date=2016-03-28 |title=Drilling-induced earthquakes may endanger millions in 2016, USGS says |url=https://www.pbs.org/newshour/science/drilling-induced-earthquakes-may-endanger-millions-in-2016-usgs-says |access-date=2025-12-04 |website=PBS News |language=en-us}}</ref> The rise in earthquakes in the area directly coincides with the increase in oil drilling activity.<ref name=":6" /> After aggressive drilling began in 2008 in Texas and Oklahoma regions, residents began feeling earthquakes, with more than 180 being recorded in Texas between October 30 of that year and May 31 of 2009.<ref name=":6" /> The largest recorded earthquake in Texas, ultimately resulting from fracking and drilling, was a 4.0 magnitude that occurred in 2018.<ref name=":5" /> A better understanding of the geology of the area being fracked and used for injection wells can be helpful in mitigating the potential for significant seismic events.<ref>{{cite book |last1=Elling |first1=Arthur E. |title=Managing Vegetation on Peat-Sand Filter Beds for Wastewater Disposal |date=1985 |doi=10.2737/nc-rn-333 }}</ref>

== Regulations ==
{{See also|Hydraulic fracturing by country|Regulation of hydraulic fracturing}}

Countries using or considering use of hydraulic fracturing have implemented different regulations, including developing federal and regional legislation, and local zoning limitations.<ref name=nolon/><ref name=Negro/> In 2011, after public pressure France became the first nation to ban hydraulic fracturing, based on the [precautionary principle](/source/precautionary_principle) as well as the principle of preventive and corrective action of environmental hazards.<ref name="Bweek 31.03.2011"/><ref name="Bweek 04.10.2011"/><ref name=autogenerated2>{{Cite web|url=https://www.legifrance.gouv.fr/loda/id/JORFTEXT000024361355/|title=LOI n° 2011-835 du 13 juillet 2011 visant à interdire l'exploration et l'exploitation des mines d'hydrocarbures liquides ou gazeux par fracturation hydraulique et à abroger les permis exclusifs de recherches comportant des projets ayant recours à cette technique (1) - Légifrance|website=www.legifrance.gouv.fr}}</ref><ref name=autogenerated5>{{Cite web|url=https://www.legifrance.gouv.fr/codes/article_lc/LEGIARTI000043084969/|title=Article L110-1 - Code de l'environnement - Légifrance|website=www.legifrance.gouv.fr}}</ref> The ban was upheld by an October 2013 ruling of the [Constitutional Council](/source/Constitutional_Council_of_France).<ref>{{cite news |url=https://www.bbc.co.uk/news/business-24489986 |title=Fracking ban upheld by French court |date=11 October 2013 |work=BBC |access-date=16 October 2013}}</ref> Some other countries such as Scotland have placed a temporary moratorium on the practice due to public health concerns and strong public opposition.<ref name=moore/> Countries like [South Africa](/source/South_Africa) have lifted their bans, choosing to focus on regulation instead of outright prohibition.<ref name=wcn170912>{{cite news|url=http://allafrica.com/stories/201209180701.html | title=South Africa: International Groups Rally Against Fracking, TKAG Claims | first = Francis | last = Hweshe | work= West Cape News | date=17 September 2012 | access-date=11 February 2014}}</ref> Germany has announced draft regulations that would allow using hydraulic fracturing for the exploitation of shale gas deposits with the exception of [wetland areas](/source/wetlands).<ref name=bloomberg260213/> In China, regulation on shale gas still faces hurdles, as it has complex interrelations with other regulatory regimes, especially trade.<ref>{{cite journal  |last1=Farah |first1=Paolo Davide |last2=Tremolada |first2=Riccardo |title=Regolazione e prospettive del mercato dello shale gas in Cina: tra diritto del commercio internazionale, diritto dell'energia, accordi di produzione, protezione ambientale e sviluppo sostenibile: un confronto con l'esperienza statunitense |trans-title=Regulation and Prospects of the Shale Gas Market in China in Light of International Trade, Energy Law, Production-Sharing Agreements, Environmental Protection and Sustainable Development: A Comparison with the US Experience |language=it |journal=Diritto Comunitario e degli Scambi Internazionali |volume=54 |issue=1–2 |date=2015 |pages=29–83 |ssrn=2666216 }}</ref> Many states in Australia have either permanently or temporarily banned fracturing for hydrocarbons.<ref>{{Cite news |date=2017-09-05 |title=Western Australia halts hydraulic fracturing, to probe risks |url=https://www.reuters.com/article/business/environment/western-australia-halts-hydraulic-fracturing-to-probe-risks-idUSKCN1BG16E/ |url-access=limited |access-date=2025-11-09 |work=[Reuters](/source/Reuters)}}</ref> In 2019, hydraulic fracturing was banned in UK.<ref>{{Cite news |url=https://www.theguardian.com/environment/2019/nov/02/fracking-banned-in-uk-as-government-makes-major-u-turn |title=Fracking banned in UK as government makes major U-turn|last=Ambrose|first=Jillian|date=2 November 2019|work=The Guardian|language=en-GB }}</ref>

The European Union has adopted a recommendation for minimum principles for using high-volume hydraulic fracturing.<ref name=recommendation/> Its regulatory regime requires full disclosure of all additives.<ref name="EU" /> 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.<ref name = "HassBenjamin" /><ref name="SoraghanMike02" /> Hydraulic fracturing is excluded from the [Safe Drinking Water Act](/source/Safe_Drinking_Water_Act)'s underground injection control's regulation, except when [diesel fuel](/source/diesel_fuel) is used. The EPA assures surveillance of the issuance of drilling permits when diesel fuel is employed.<ref name="autogenerated4">{{cite web |url=http://water.epa.gov/type/groundwater/uic/class2/hydraulicfracturing/wells_hydroreg.cfm |title=Regulation of Hydraulic Fracturing Under the Safe Drinking Water Act |publisher=Environmental Protection Agency |access-date=6 July 2025 |archive-date=23 September 2015 |archive-url=https://web.archive.org/web/20150923182940/http://water.epa.gov/type/groundwater/uic/class2/hydraulicfracturing/wells_hydroreg.cfm |url-status=dead }}</ref>

In 2012, Vermont became the first state in the United States to ban hydraulic fracturing. On 17 December 2014, New York became the second state to issue a complete ban on any hydraulic fracturing due to potential risks to human health and the environment.<ref name="NYT-20141217">{{cite news |id={{ProQuest|1637440501}} | title = Gov. Cuomo Makes Sense on Fracking | url = https://www.nytimes.com/2014/12/18/opinion/gov-cuomo-makes-sense-on-fracking.html |date=17 December 2014 | work= The New York Times |access-date=18 December 2014 }}</ref><ref name=tu181214>{{cite news | url = https://www.timesunion.com/local/article/State-1st-in-U-S-to-ban-fracking-5964402.php | title = Citing perils, state bans fracking | first = Brian | last = Nearing | date=18 December 2014 | work= [Times Union](/source/Times_Union_(Albany)) |access-date=25 January 2015}}</ref><ref name=npr181214>{{cite news|last1=Brady|first1=Jeff|title=Citing Health, Environment Concerns, New York Moves To Ban Fracking|url=https://www.npr.org/2014/12/18/371597785/citing-heath-environment-concerns-new-york-moves-to-ban-fracking| work = [NPR](/source/NPR) |date=18 December 2014 |access-date=25 January 2015}}</ref>

== See also ==
{{Portal|Earth sciences|Energy|Environment}}
* [Directional drilling](/source/Directional_drilling)
* [Environmental impact of electricity generation](/source/Environmental_impact_of_electricity_generation)
* [Environmental effects of petroleum](/source/Environmental_effects_of_petroleum)
* [Fracking by country](/source/Fracking_by_country)
* [Fracking in the United States](/source/Fracking_in_the_United_States)
* [Fracking in the United Kingdom](/source/Fracking_in_the_United_Kingdom)
* [In situ leach](/source/In_situ_leach)
* [New York energy law#Hydrofracking](/source/New_York_energy_law)
* [Nuclear power](/source/Nuclear_power)
* [Peak oil](/source/Peak_oil)
* [Stranded asset](/source/Stranded_asset)
* [Shale oil extraction](/source/Shale_oil_extraction)
* [Vaca Muerta](/source/Vaca_Muerta)

==Notes and references==
===Explanatory notes===
{{Notelist}}

===References===
{{EPA content|title=Hydraulic Fracturing for Oil and Gas: Impacts from the Hydraulic Fracturing Water Cycle on Drinking Water Resources in the United States (Final Report)|url=https://cfpub.epa.gov/ncea/hfstudy/recordisplay.cfm?deid=332990|publisher=United States Environmental Protection Agency|access-date=17 December 2016 }}

<references>
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<ref name="aea2012">{{cite report | title = Support to the identification of potential risks for the environment and human health arising from hydrocarbons operations involving hydraulic fracturing in Europe | url = http://ec.europa.eu/environment/integration/energy/pdf/fracking%20study.pdf | first = Mark | last = Broomfield | publisher = [European Commission](/source/European_Commission) | date = 10 August 2012 | access-date = 29 September 2014 | pages = vi–xvi | id = ED57281 | issue = 17c}}</ref>

<ref name=Arthur>{{cite report|url=http://www.aogc.state.ar.us/ALL%20FayettevilleFrac%20FINAL.pdf |title=Hydraulic Fracturing Considerations for Natural Gas Wells of the Fayetteville Shale |first1=J. Daniel |last1=Arthur |first2=Brian |last2=Bohm |first3=Bobbi Jo |last3=Coughlin |first4=Mark |last4=Layne |year=2008 |page=10 |publisher=ALL Consulting |access-date=7 May 2012 |archive-url=https://web.archive.org/web/20121015081325/http://www.aogc.state.ar.us/ALL%20FayettevilleFrac%20FINAL.pdf |archive-date=15 October 2012 }}</ref>

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<ref name="AutoZV-38">{{cite news|last=Phillips|first=Susan|title='We're Dealing with an Insurgency,' says Energy Company Exec of Fracking Foes|url=https://stateimpact.npr.org/pennsylvania/2011/11/09/were-dealing-with-an-insurgency-says-energy-company-exec-of-fracking-foes/|work=[National Public Radio](/source/National_Public_Radio)|date=9 November 2011}}</ref>

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<ref name="AutoZV-7">{{cite book |last=Brown |first=Edwin Thomas |year=2007 |orig-date=2003 |title=Block Caving Geomechanics |edition=2nd |location=Indooroopilly, Queensland |publisher=[Julius Kruttschnitt Mineral Research Centre, UQ](/source/University_of_Queensland) |isbn=978-0-9803622-0-6 |url=https://www.jkmrc.uq.edu.au/jkmrc-block-caving-geomechanics-second-edition |access-date=14 May 2012}}</ref>

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<ref name=bloomberg260213>{{cite news | url = https://www.bloomberg.com/news/2013-02-26/germany-agrees-on-regulation-to-permit-fracking-for-shale-gas.html |title= Germany agrees on regulations to allow fracking for shale gas |first1= Stefan |last1= Nicola | first2 = Tino | last2 = Andersen |date= 26 February 2013 |agency= Bloomberg |access-date= 1 May 2014}}</ref>

<ref name="Bloomberg 11.01.2012">{{cite news |url=https://www.bloomberg.com/news/2012-01-11/fracking-s-political-support-unshaken-by-doctors-call-for-ban.html |title=Fracking Political Support Unshaken by Doctors' Call for Ban | first=Mark | last = Drajem |date=11 January 2012 |agency=Bloomberg |access-date=19 January 2012}}</ref>

<ref name="EHP VJBrown">{{cite journal |title=Radionuclides in Fracking Wastewater: Managing a Toxic Blend|author=V. J. Brown|date=February 2014|journal=[Environmental Health Perspectives](/source/Environmental_Health_Perspectives)|volume=122 | issue = 2 |pages=A50–A55 |doi=10.1289/ehp.122-A50 |doi-broken-date=2 January 2026 |pmid=24486733 |pmc=3915249 |bibcode=2014EnvHP.1222.A50B }}</ref>

<ref name="bmp">{{cite web|title = Hydraulic Fracturing | url=https://www.oilandgasbmps.org/resources/fracing.php |publisher = [University of Colorado Law School](/source/University_of_Colorado_Law_School) | access-date= 2 June 2012}}</ref>

<ref name="BW 04Jan2012">{{cite news|url=http://www.businessweek.com/news/2012-01-10/health-effects-of-fracking-need-study-says-cdc-scientist.html |title=Health Effects of Fracking Need Study, Says CDC Scientist |author=Alex Wayne |date=4 January 2012 |work=Bloomberg Businessweek |access-date=29 February 2012 |archive-url=https://web.archive.org/web/20120313051634/http://www.businessweek.com/news/2012-01-10/health-effects-of-fracking-need-study-says-cdc-scientist.html |archive-date=13 March 2012 }}</ref>

<ref name="BW 19.01.2012">{{cite news |url=http://www.businessweek.com/magazine/like-fracking-youll-love-super-fracking-01192012.html |archive-url=https://web.archive.org/web/20120123022140/http://www.businessweek.com/magazine/like-fracking-youll-love-super-fracking-01192012.html |archive-date=23 January 2012 |title=Like Fracking? You'll Love 'Super Fracking' |author=David Wethe |date=19 January 2012 |work=Businessweek |access-date=22 January 2012}}</ref>

<ref name="Bweek 04.10.2011">{{cite news |url=http://www.businessweek.com/news/2011-10-04/france-to-keep-fracking-ban-to-protect-environment-sarkozy-says.html |archive-url=https://web.archive.org/web/20111008000938/http://www.businessweek.com/news/2011-10-04/france-to-keep-fracking-ban-to-protect-environment-sarkozy-says.html |archive-date=8 October 2011 |title=France to Keep Fracking Ban to Protect Environment, Sarkozy Says |first =Tara | last = Patel |date=4 October 2011 | work = [Bloomberg Businessweek](/source/Bloomberg_Businessweek) |access-date=22 February 2012}}</ref>

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<ref name="Canada">{{cite report |url= http://www.capp.ca/getdoc.aspx?DocId=210903&DT=NTV |title= The Modern Practices of Hydraulic Fracturing: A Focus on Canadian Resources |date= June 2012 |author= ALL Consulting |publisher= Canadian Association of Petroleum Producers |format= PDF |access-date= 4 August 2012 |archive-date= 18 May 2013 |archive-url= https://web.archive.org/web/20130518222938/http://www.capp.ca/getdoc.aspx?DocId=210903&DT=NTV }}</ref>

<ref name="Charlez">{{cite book |last=Charlez |first=Philippe A. |year=1997 |title=Rock Mechanics: Petroleum Applications |location=Paris |publisher=Editions Technip |url =https://books.google.com/books?id=NigwG_BYRsYC&pg=PA239 | page = 239| access-date = 14 May 2012 |isbn=978-2-7108-0586-1}}</ref>

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<ref name=COGCC>[http://cogcc.state.co.us/library/GASLAND%20DOC.pdf COGCC Gasland Correction Document] {{webarchive|url=https://web.archive.org/web/20130905130921/http://cogcc.state.co.us/library/GASLAND%20DOC.pdf |date=5 September 2013 }} ''[Colorado Department of Natural Resources](/source/Colorado_Department_of_Natural_Resources)'' 29 October 2010</ref>

<ref name="CRO 2009">{{cite report |url= https://fas.org/sgp/crs/misc/R40894.pdf |title=Unconventional Gas Shales: Development, Technology, and Policy Issues |author= Andrews, Anthony|date=30 October 2009 |publisher=Congressional Research Service |access-date=22 February 2012| pages = 7; 23|display-authors=etal}}</ref>

<ref name = Deller>{{cite journal | first1 = Steven | last1 = Deller | first2 = Andrew | last2 = Schreiber | year = 2012 | journal = The Review of Regional Studies | volume = 42 | pages = 121–141 | title = Mining and Community Economic Growth | issue = 2 | doi = 10.52324/001c.8126 | doi-access = free }}</ref>

<ref name="DetrowScott">{{cite news |url= https://stateimpact.npr.org/pennsylvania/2012/08/15/pipe-bomb-found-near-allegheny-county-pipeline/ |first=Scott |last=Detrow |date=15 August 2012 |work= NPR | title= Pipe Bomb Found Near Allegheny County Pipeline | access-date=27 March 2013}}</ref>

<ref name="DOE primer">{{cite report |url= http://energy.gov/sites/prod/files/2013/03/f0/ShaleGasPrimer_Online_4-2009.pdf |title=Modern Shale Gas Development in the United States: A Primer |author1=Ground Water Protection Council |author2=ALL Consulting | date=April 2009 |publisher=[DOE Office of Fossil Energy](/source/Assistant_Secretary_for_Fossil_Energy) and [National Energy Technology Laboratory](/source/National_Energy_Technology_Laboratory) |access-date=24 February 2012|id= DE-FG26-04NT15455 |pages=56–66}}</ref>

<ref name="Economides">{{cite book | title= Reservoir stimulation | year = 2000 | first1 = Michael J. | last1 = Economides | publisher = [J. Wiley](/source/J._Wiley) | page = P-2 | isbn = 978-0-471-49192-7}}</ref>

<ref name="ECStimTech">{{cite book |author1=[Institute for Energy and Transport](/source/Institute_for_Energy_and_Transport) |title=An overview of hydraulic fracturing and other formation stimulation technologies for shale gas production: Update 2015 |date=2015 |publisher=Publications Office |doi=10.2790/379646 |isbn=978-92-79-53894-0 |doi-access=free }}{{pn|date=January 2026}}</ref>

<ref name="epa-ord">{{cite web|url=http://www.epa.gov/safewater/uic/pdfs/hfresearchstudyfs.pdf |title=Hydraulic fracturing research study |date=June 2010 |publisher=[EPA](/source/United_States_Environmental_Protection_Agency) |access-date=26 December 2012 |id=EPA/600/F-10/002 |archive-url=https://web.archive.org/web/20121203005215/http://www.epa.gov/safewater/uic/pdfs/hfresearchstudyfs.pdf |archive-date=3 December 2012 }}</ref>

<ref name="EU">{{cite report | url = http://www.epa.ie/pubs/reports/research/sss/UniAberdeen_FrackingReport.pdf | title = Hydraulic Fracturing or 'Fracking': A Short Summary of Current Knowledge and Potential Environmental Impacts | first = Dave | last = Healy | date = July 2012 | publisher = [Environmental Protection Agency](/source/Environmental_Protection_Agency_(Ireland))| access-date = 28 July 2013 }}</ref>

<ref name="Fjaer">{{cite book|last=Fjaer|first=E.|title=Petroleum related rock mechanics|chapter-url=https://books.google.com/books?id=l6CfasFxhzYC&pg=PA369 |edition=2nd|series=Developments in petroleum science|year=2008|publisher=[Elsevier](/source/Elsevier) |isbn=978-0-444-50260-5|page=369|chapter=Mechanics of hydraulic fracturing|access-date=14 May 2012}}</ref>

<ref name="Fracmaps">{{cite web|author=<!--Staff writer(s); no by-line.-->|title= State by state maps of hydraulic fracturing in US. |publisher=Fractracker.org|url=https://www.fractracker.org/maps/|access-date=19 October 2013}}</ref>
<ref name="freeing">{{cite web | url= http://www.api.org/policy/exploration/hydraulicfracturing/upload/HYDRAULIC_FRACTURING_PRIMER.pdf |archive-url=https://web.archive.org/web/20121113105130/http://www.api.org/policy/exploration/hydraulicfracturing/upload/HYDRAULIC_FRACTURING_PRIMER.pdf |archive-date=13 November 2012 |title= Freeing Up Energy. Hydraulic Fracturing: Unlocking America's Natural Gas Resources |website=[American Petroleum Institute](/source/American_Petroleum_Institute) | date = 19 July 2010 | access-date = 29 December 2012}}</ref>

<ref name="Geosoc yield">{{cite web |url=http://geology.com/royalty/production-decline.shtml |title=Production Decline of a Natural Gas Well Over Time |date=3 January 2012 |work=Geology.com |publisher=The Geology Society of America |access-date=4 March 2012 |archive-date=26 November 2020 |archive-url=https://web.archive.org/web/20201126234513/https://geology.com/royalty/production-decline.shtml |url-status=dead }}</ref>

<ref name="Gill">{{cite book|last=Gill|first=R.|title=Igneous rocks and processes: a practical guide|url=https://books.google.com/books?id=vgpmAcu_M-AC&pg=PA102|year=2010|publisher=[John Wiley and Sons](/source/John_Wiley_and_Sons) |isbn=978-1-4443-3065-6 |page=102}}</ref>
<ref name="HassBenjamin">{{cite news |url=https://www.bloomberg.com/news/2012-08-14/fracking-hazards-obscured-in-failure-to-disclose-wells.html |title=Fracking Hazards Obscured in Failure to Disclose Wells |first=Benjamin |last=Hass |date=14 August 2012 | agency=Bloomberg |access-date=27 March 2013}}</ref>

<ref name=gri>{{cite book |title= A review of the management of the Gas Research Institute |publisher=National Academies |year= 1989}}</ref>

<ref name=guardian010313>Wasley, Andrew (1 March 2013) [https://www.theguardian.com/environment/2013/mar/01/frontline-poland-fracking-frontier On the frontline of Poland's fracking rush] The Guardian, Retrieved 3 March 2013</ref>

<ref name=Hartnett>{{cite magazine|last=Hartnett-White|first=K.|title=The Fracas About Fracking- Low Risk, High Reward, but the EPA is Against it|magazine=National Review Online|url=https://www.energyindepth.org/wp-content/uploads/2011/06/The-Fracas-about-Fracking.pdf|year=2011|access-date=7 May 2012}}</ref>

<ref name=hazmat40.2>{{cite journal |title=Remediation of low permeability subsurface formations by fracturing enhancement of soil vapor extraction |journal=Journal of Hazardous Materials |volume=40 |issue= 2 |date=February 1995 |pages=191–201 |doi=10.1016/0304-3894(94)00069-S |last1=Frank |first1=U. |last2=Barkley |first2=N. |bibcode=1995JHzM...40..191F |url=https://zenodo.org/record/1258461 }}</ref>

<ref name="HeatOnGas">{{Cite journal |last=Brown |first=Valerie J. |title=Industry Issues: Putting the Heat on Gas |date=February 2007 |journal=Environmental Health Perspectives |page=A76 |volume=115 |issue=2 |doi=10.1289/ehp.115-a76 |doi-broken-date=2 January 2026 |pmc=1817691 |pmid=17384744 }}</ref>

<ref name="house1">{{cite report|url=http://democrats.energycommerce.house.gov/sites/default/files/documents/Hydraulic%20Fracturing%20Report%204.18.11.pdf |publisher=Committee on Energy and Commerce U.S. House of Representatives |title=Chemicals Used in Hydraulic Fracturing |date=18 April 2011 |page=? |archive-url=https://web.archive.org/web/20110721042543/http://democrats.energycommerce.house.gov/sites/default/files/documents/Hydraulic%20Fracturing%20Report%204.18.11.pdf |archive-date=21 July 2011 }}</ref>

<ref name="IAEA 2003">{{cite report |url=https://www-pub.iaea.org/MTCD/publications/PDF/Pub1171_web.pdf|title= Radiation Protection and the Management of Radioactive Waste in the Oil and Gas Industry |date=2003 |publisher=International Atomic Energy Agency |access-date=20 May 2012| pages = 39–40 |quote=Beta emitters, including <sup>3</sup>H and <sup>14</sup>C, may be used when it is feasible to use sampling techniques to detect the presence of the radiotracer, or when changes in activity concentration can be used as indicators of the properties of interest in the system. Gamma emitters, such as <sup>46</sup>Sc, <sup>140</sup>La, <sup>56</sup>Mn, <sup>24</sup>Na, <sup>124</sup>Sb, <sup>192</sup>Ir, <sup>99</sup>Tc<sup>m</sup>, <sup>131</sup>I, <sup>110</sup>Ag<sup>m</sup>, <sup>41</sup>Ar and <sup>133</sup>Xe are used extensively because of the ease with which they can be identified and measured. ... In order to aid the detection of any spillage of solutions of the 'soft' beta emitters, they are sometimes spiked with a short half-life gamma emitter such as <sup>82</sup>Br}}</ref>

<ref name=indepth>{{cite web |title=Gasland Debunked |publisher=Energy in Depth |url=https://www.energyindepth.org/wp-content/uploads/2011/11/Debunking-Gasland.pdf|access-date = 14 May 2012}}</ref>

<ref name="interpress08072013">{{cite news |url=https://www.ipsnews.net/2013/08/govt-energy-industry-accused-of-suppressing-fracking-dangers/ |title=Govt, Energy Industry Accused of Suppressing Fracking Dangers|author=Jared Metzker |date=7 August 2013 |publisher=[Inter Press Service](/source/Inter_Press_Service) |access-date=28 December 2013}}</ref>
<ref name="Kim">{{cite journal |last1=Kim |first1=Won-Young |title=Induced seismicity associated with fluid injection into a deep well in Youngstown, Ohio |journal=Journal of Geophysical Research: Solid Earth |date=2013 |volume=118 |issue=7 |pages=3506–3518 |doi=10.1002/jgrb.50247 |bibcode=2013JGRB..118.3506K }}</ref>

<ref name="Laubach">{{cite journal |last1=Laubach |first1=S.E |last2=Reed |first2=R.M |last3=Olson |first3=J.E |last4=Lander |first4=R.H |last5=Bonnell |first5=L.M |title=Coevolution of crack-seal texture and fracture porosity in sedimentary rocks: Cathodoluminescence observations of regional fractures |journal=Journal of Structural Geology |date=2004 |volume=26 |issue=5 |pages=967–982 |doi=10.1016/j.jsg.2003.08.019 |bibcode=2004JSG....26..967L }}</ref>

<ref name="LoganJeffrey">{{cite report |title=Natural Gas and the Transformation of the U.S. Energy Sector: Electricity |first=Jeffrey |last=Logan |publisher=Joint Institute for Strategic Energy Analysis | url=http://www.nrel.gov/docs/fy13osti/55538.pdf | year = 2012 |access-date=27 March 2013}}</ref>

<ref name="Love">{{cite web|url=http://www.johnsonwright.net/newsletters/2011-December/Fracking-The_Controversy_Over_its_Safety_for_the_Environment.htm |title=Fracking: The Controversy Over its Safety for the Environment |date=December 2005 |last1=Love |first1=Adam H. |publisher=Johnson Wright, Inc. |access-date=10 June 2012 |archive-url=https://web.archive.org/web/20130501060306/http://www.johnsonwright.net/newsletters/2011-December/Fracking-The_Controversy_Over_its_Safety_for_the_Environment.htm |archive-date=1 May 2013 }}</ref>

<ref name=Mader>{{cite book |title= Hydraulic Proppant Fracturing and Gravel Packing | url = https://books.google.com/books?id=FyGcOI42oBMC&pg=PA174 | year= 1989 | first= Detlef | last = Mader | publisher = [Elsevier](/source/Elsevier) | isbn = 978-0-444-87352-1 | pages = 173–174; 202}}</ref>

<ref name="Manthei">{{cite book|last1=Manthei|first1=G.|last2=Eisenblätter|first2=J.|last3=Kamlot|first3=P.|editor=Natau, Fecker & Pimentel|title=Geotechnical Measurements and Modelling|chapter-url=http://www.gmugmbh.de/download/gmug_Scan0965.pdf|access-date=6 March 2012|year=2003|isbn=978-90-5809-603-6|pages=355–360|chapter=Stress measurement in salt mines using a special hydraulic fracturing borehole tool|publisher=CRC Press }}</ref>

<ref name="Miller">{{cite book |url= https://books.google.com/books?id=PYyJEEyJN94C&pg=PA380 |title= Coal Energy Systems | series = Sustainable World Series | year = 2005 | last1 = Miller | first1 = Bruce G. | publisher = [Academic Press](/source/Academic_Press) | page = 380 | isbn = 978-0-12-497451-7}}</ref>

<ref name="Montgomery">{{cite journal |last1=Montgomery |first1=Carl T. |last2=Smith |first2=Michael B. |title=Hydraulic Fracturing: History of an Enduring Technology |journal=Journal of Petroleum Technology |date=2010 |volume=62 |issue=12 |pages=26–40 |doi=10.2118/1210-0026-JPT |bibcode=2010JPetT..62...26M }}</ref>

<ref name="mooney">{{cite journal |last1=Mooney |first1=Chris |title=The Truth about Fracking |journal=Scientific American |date=18 October 2011 |volume=305 |issue=5 |pages=80–85 |doi=10.1038/scientificamerican1111-80|pmid=22125868 |bibcode=2011SciAm.305d..80M }}</ref>
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<ref name=moore>{{cite web|last=Moore|first=Robbie|title=Fracking, PR, and the Greening of Gas|url=http://www.theinternational.org/articles/369-fracking-pr-and-the-greening-of-gas|work=The International|access-date=16 March 2013|archive-url=https://web.archive.org/web/20130321211142/http://www.theinternational.org/articles/369-fracking-pr-and-the-greening-of-gas|archive-date=21 March 2013}}</ref>
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<ref name=Negro>{{cite journal | last = Negro | first = Sorrell E. | title = Fracking Wars: Federal, State, and Local Conflicts over the Regulation of Natural Gas Activities | url = https://www.ourenergypolicy.org/wp-content/uploads/2013/07/Fracking-Wars.pdf | journal = Zoning and Planning Law Report | volume = 35 | issue = 2 | date = February 2012 | pages = 1–14 | access-date = 1 May 2014}}</ref>
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<ref name=nge070812>(7 August 2012) [http://www.naturalgaseurope.com/jkx-awards-fracking-contract-for-ukrainian-prospect JKX Awards Fracking Contract for Ukrainian Prospect] Natural Gas Europe, Retrieved 3 March 2013</ref>
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<ref name=nolon>{{Cite journal |last1=Nolon |first1=John R. |last2= Polidoro |first2= Victoria | title= Hydrofracking: Disturbances Both Geological and Political: Who Decides? |year= 2012 |journal= The Urban Lawyer |pages=1–14 |volume=44 |issue=3 | url = http://environment.yale.edu/content/documents/00002783/Hydrofracking-Disturbances-Both-Geological-and-Political-Who-Decides.pdf |access-date=21 December 2012}}</ref>
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<ref name="NRC">{{cite web |url=https://www.nrc.gov/reading-rm/doc-collections/nuregs/staff/sr1556/v14/#_1_26 |title=Consolidated Guidance About Materials Licenses: Program-Specific Guidance About Well Logging, Tracer, and Field Flood Study Licenses (NUREG-1556, Volume 14) |author=Jack E. Whitten |author2=Steven R. Courtemanche |author3=Andrea R. Jones |author4=Richard E. Penrod |author5=David B. Fogl |quote=labeled Frac Sand...Sc-46, Br-82, Ag-110m, Sb-124, Ir-192 |date=June 2000 |publisher=US Nuclear Regulatory Commission|access-date=19 April 2012}}</ref>
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<ref name="NYT Docs">{{cite news |url=https://www.nytimes.com/interactive/2011/02/27/us/natural-gas-documents-1.html#document/p533/a9948 |title=Natural Gas Documents |date=27 February 2011 |work=The New York Times |access-date=5 May 2012 |quote=The Times reviewed more than 30,000 pages of documents obtained through open records requests of state and federal agencies and by visiting various regional offices that oversee drilling in Pennsylvania. Some of the documents were leaked by state or federal officials.}}</ref>
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<ref name="NYT lobbying docs">{{cite news |url=https://www.nytimes.com/interactive/2011/03/04/us/20110304_natural-gas-documents-intro.html |title=The Debate Over the Hydrofracking Study's Scope |quote= While environmentalists have aggressively lobbied the agency to broaden the scope of the study, industry has lobbied the agency to narrow this focus |date=3 March 2011 |work= The New York Times |access-date=1 May 2012}}</ref>
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<ref name="Oilfield Review 2005/2006">{{cite journal | url = https://www.slb.com/~/media/Files/resources/oilfield_review/ors05/win05/04_the_source_for_hydraulic.ashx | title = The Source for Hydraulic Fracture Characterization | journal = Oilfield Review | pages = 42–57 | issue = Winter 2005/2006 | author = Bennet, Les | format = PDF | access-date = 30 September 2012 | display-authors = etal | archive-url = https://web.archive.org/web/20140825144515/https://www.slb.com/~/media/Files/resources/oilfield_review/ors05/win05/04_the_source_for_hydraulic.ashx | archive-date = 25 August 2014 }}</ref>
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<ref name="PalmerMike">{{cite news |url = http://www.timesleaderonline.com/page/content.detail/id/545690/Oil-gas-boom-spawns-Harrison-safety-talks.html?nav=5010 |first=Mike |last=Palmer |date=27 March 2013 | work=Times Leader | title=Oil-gas boom spawns Harrison safety talks | access-date=27 March 2013}}</ref>
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<ref name="Penn State Water">{{cite report |title=Water Withdrawals for Development of Marcellus Shale Gas in Pennsylvania. Introduction to Pennsylvania's Water Resources |first1=Charles W. |last1=Abdalla |first2=Joy R. |last2=Drohan |publisher=[The Pennsylvania State University](/source/The_Pennsylvania_State_University) |quote=Hydrofracturing a horizontal Marcellus well may use 4 to 8 million gallons of water, typically within about 1 week. However, based on experiences in other major U.S. shale gas fields, some Marcellus wells may need to be hydrofractured several times over their productive life (typically five to twenty years or more) |url=http://pubs.cas.psu.edu/FreePubs/pdfs/ua460.pdf |year=2010 |access-date=16 September 2012 |archive-date=2 March 2015 |archive-url=https://web.archive.org/web/20150302155258/http://pubs.cas.psu.edu/FreePubs/pdfs/ua460.pdf }}</ref>
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<ref name="Penny">{{cite journal|last1=Penny |first1=Glenn S. |last2=Conway |first2=Michael W. |last3=Lee |first3=Wellington |title=Control and Modeling of Fluid Leakoff During Hydraulic Fracturing |date=June 1985 |pages=1071–1081 |volume=37 |issue=6 |journal=Journal of Petroleum Technology |doi=10.2118/12486-PA }}</ref>
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<ref name="petrowiki">{{cite web | url= http://petrowiki.spe.org/Acid_fracturing | title = Acid fracturing | publisher = [Society of Petroleum Engineers](/source/Society_of_Petroleum_Engineers) | access-date = 12 October 2014}}</ref>
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<ref name="PhillyInq001">{{cite news |url=http://www.philly.com/philly/news/20130311_ap_shotsfiredatwpagasdrillingsite.html |date=12 March 2013 |work=[The Philadelphia Inquirer](/source/The_Philadelphia_Inquirer) |title=Shots fired at W. Pa. gas drilling site |access-date=27 March 2013 |archive-date=29 July 2013 |archive-url=https://web.archive.org/web/20130729153802/http://www.philly.com/philly/news/20130311_ap_shotsfiredatwpagasdrillingsite.html }}</ref>
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<ref name="Promised Land">{{cite news |first= Daniel | last = Gilbert |date= 7 October 2012 | url-access=subscription |title = Matt Damon Fracking Film Lights Up Petroleum Lobby | url = https://www.wsj.com/articles/SB10000872396390443294904578042620641185816#articleTabs%3Darticle | work= The Wall Street Journal |access-date= 26 December 2012 }}</ref>
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<ref name=progressive>{{Cite news|last=Gerhardt|first=Tina|date=31 December 2012|title=Matt Damon Exposes Fracking in Promised Land|url=https://www.progressive.org/matt-damon-exposes-fracking-in-promised-land|work=[The Progressive](/source/The_Progressive) | access-date = 4 January 2013}}</ref>
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<ref name=psyops>{{cite news|last=Javers|first=Eamon|title=Oil Executive: Military-Style 'Psy Ops' Experience Applied|url=https://www.cnbc.com/2011/11/08/oil-executive-militarystyle-psy-ops-experience-applied.html|work=[CNBC](/source/CNBC)|date=8 November 2011}}</ref>
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<ref name=recommendation>{{cite web |url= http://eur-lex.europa.eu/LexUriServ/LexUriServ.do?uri=OJ:L:2014:039:0072:0078:EN:PDF |title= Commission recommendation on minimum principles for the exploration and production of hydrocarbons (such as shale gas) using high-volume hydraulic fracturing (2014/70/EU) | date = 22 January 2014 | work = [Official Journal of the European Union](/source/Official_Journal_of_the_European_Union) | access-date= 13 March 2014}}</ref>
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<ref name="Reis iodine">Reis, John C. (1976). ''Environmental Control in Petroleum Engineering.'' Gulf Professional Publishers.</ref>
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<ref name="Renpu">{{cite book |url= https://books.google.com/books?id=GH6JoDxT_9sC&pg=PA424 |title= Advanced Well Completion Engineering | year = 2011 | author = Wan Renpu | publisher = [Gulf Professional Publishing](/source/Gulf_Professional_Publishing) | page = 424 | isbn = 978-0-12-385868-9}}</ref>
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<ref name=reuters180213>(18 February 2013) [https://www.reuters.com/article/turkey-shale-idUSL6N0BI8CQ20130218 Turkey's shale gas hopes draw growing interest] Reuters, Retrieved 3 March 2013</ref>
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<ref name="shale Europe">{{cite web |last= Faucon |first= Benoît |date= 17 September 2012 | title= Shale-Gas Boom Hits Eastern Europe |url= https://www.wsj.com/articles/SB10000872396390443866404577565244220252020 | publisher=[WSJ.com](/source/WSJ.com) |access-date= 17 September 2012}}</ref>
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<ref name="shooters">{{cite web | url= https://aoghs.org/technology/hydraulic-fracturing/ | title = Shooters – A "Fracking" History | publisher = American Oil & Gas Historical Society | access-date = 12 October 2014}}</ref>
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<ref name="Sibson">{{cite journal |last1=Sibson |first1=R. H. |last2=Moore |first2=J. Mc. M. |last3=Rankin |first3=A. H. |title=Seismic pumping—a hydrothermal fluid transport mechanism |journal=Journal of the Geological Society |date=1975 |volume=131 |issue=6 |pages=653–659 |doi=10.1144/gsjgs.131.6.0653 |bibcode=1975JGSoc.131..653S }}</ref>
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<ref name="SoraghanMike">{{cite news |url=http://www.eenews.net/public/energywire/2012/03/12/1 |title=Quiet foundation funds the 'anti-fracking' fight |first=Mike |last=Soraghan |date=12 March 2012 |work=E&E News | quote="In our work to oppose fracking, the Park Foundation has simply helped to fuel an army of courageous individuals and NGOs,' or non-governmental organizations, said Adelaide Park Gomer, foundation president and Park heir, in a speech late last year." | access-date=27 March 2013}}</ref>
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<ref name="SoraghanMike02">{{cite news |url=http://www.eenews.net/eenewspm/2012/06/21/archive/2 |title=White House official backs FracFocus as preferred disclosure method |first=Mike |last=Soraghan |date=13 December 2013 |work=E&E News |access-date=27 March 2013 |archive-date=31 October 2020 |archive-url=https://web.archive.org/web/20201031184932/https://www.eenews.net/eenewspm/stories/1059966296 }}</ref>
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<ref name="undeerc">{{cite web | url= http://www.undeerc.org/bakken/completiontechnologies.aspx | title= Completion Technologies | publisher= [EERC](/source/Energy_and_Environmental_Research_Center) | access-date= 30 September 2012 | archive-date= 8 August 2020 | archive-url= https://web.archive.org/web/20200808073943/https://undeerc.org/bakken/completiontechnologies.aspx | url-status= dead }}</ref>
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<ref name="Urbina 03Mar2011">{{cite news |url=https://www.nytimes.com/2011/03/04/us/04gas.html |title=Pressure Limits Efforts to Police Drilling for Gas |first=Ian |last=Urbina |quote=More than a quarter-century of efforts by some lawmakers and regulators to force the federal government to police the industry better have been thwarted, as E.P.A. studies have been repeatedly narrowed in scope and important findings have been removed |date=3 March 2011 |work=The New York Times |access-date=23 February 2012}}</ref>
33
<ref name=upenn>{{cite web |url=https://www.law.upenn.edu/blogs/regblog/2012/08/8-narayan-guar-gum.html |title=From Food to Fracking: Guar Gum and International Regulation |author=Ram Narayan |date=8 August 2012 |work=RegBlog |publisher=[University of Pennsylvania Law School](/source/University_of_Pennsylvania_Law_School) |access-date=15 August 2012 |archive-date=22 August 2012 |archive-url=https://web.archive.org/web/20120822153712/https://www.law.upenn.edu/blogs/regblog/2012/08/8-narayan-guar-gum.html }}</ref>
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<ref name="UT Study">{{cite report |title=Fact-Based Regulation for Environmental Protection in Shale Gas Development |url=http://cewc.colostate.edu/wp-content/uploads/2012/02/ei_shale_gas_regulation120215.pdf |author=Energy Institute |publisher=[University of Texas at Austin](/source/University_of_Texas_at_Austin)  |date=February 2012 |access-date=29 February 2012 |archive-url=https://web.archive.org/web/20130512112923/http://cewc.colostate.edu/wp-content/uploads/2012/02/ei_shale_gas_regulation120215.pdf |archive-date=12 May 2013 }}</ref>
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<ref name="WEO2012 Special">{{cite book |url= http://www.worldenergyoutlook.org/media/weowebsite/2012/goldenrules/WEO2012_GoldenRulesReport.pdf |title= Golden Rules for a Golden Age of Gas. World Energy Outlook Special Report on Unconventional Gas |date= 29 May 2012 | author=IEA | publisher = [OECD](/source/Organisation_for_Economic_Co-operation_and_Development) | pages = 18–27 |author-link= International Energy Agency }}</ref>
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<ref name="Zoback">{{cite book|last=Zoback|first=M.D.|title=Reservoir geomechanics|url=https://books.google.com/books?id=Xx63OaM2JIIC&pg=PA18 |access-date=6 March 2012|year=2007|publisher=Cambridge University Press|page=18|isbn=978-0-521-14619-7}}</ref>
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==Sources==
* {{cite report |url=https://www.gov.uk/government/uploads/system/uploads/attachment_data/file/332837/PHE-CRCE-009_3-7-14.pdf |title=Review of the Potential Public Health Impacts of Exposures to Chemical and Radioactive Pollutants as a Result of the Shale Gas Extraction Process | first1 = A. | last1 = Kibble | first2 = T. | last2 = Cabianca | first3 = Z. | last3 = Daraktchieva | first4 = T. | last4 = Gooding | first5 = J. | last5 = Smithard | first6 = G. | last6 = Kowalczyk | first7 = N. P. | last7 = McColl | first8 = M. | last8 = Singh | first9 = L. | last9 = Mitchem | first10 = P. | last10 = Lamb | first11 = S. | last11 = Vardoulakis | first12 = R. | last12 = Kamanyire |publisher=Public Health England |docket=PHE-CRCE-009 |date=June 2014 |isbn = 978-0-85951-752-2 }}

==Further reading==
{{refbegin|2}}
* {{cite report |url=http://extension.psu.edu/natural-resources/water/marcellus-shale/waste-water/current-and-emerging-treatment-and-disposal-technologies |title=Marcellus Shale Wastewater Issues in Pennsylvania{{snd}}Current and Emerging Treatment and Disposal Technologies |last1=Abdalla |first1=Charles W. |last2=Drohan |first2=Joy R. |last3=Blunk |first3=Kristen Saacke |last4=Edson |first4=Jessie |date=2014 |publisher=Penn State Extension |access-date=11 October 2014 |archive-date=25 October 2014 |archive-url=https://web.archive.org/web/20141025115220/http://extension.psu.edu/natural-resources/water/marcellus-shale/waste-water/current-and-emerging-treatment-and-disposal-technologies }}
* {{cite journal |title=Measurements of methane emissions at natural gas production sites in the United States |last1=Allen |first1=David T. |last2=Torres |first2=Vincent N. |last3=Thomas |first3=James |last4=Sullivan |first4=David W. |last5=Harrison |first5=Matthew |last6=Hendler |first6=Al |last7=Herndon |first7=Scott C. |last8=Kolb |first8=Charles E. |last9=Fraser |first9=Matthew P. |last10=Hill |first10=A. Daniel |last11=Lamb |first11=Brian K. |last12=Miskimins |first12=Jennifer |last13=Sawyer |first13=Robert F. |last14=Seinfeld |first14=John H. |journal=Proceedings of the National Academy of Sciences |doi=10.1073/pnas.1304880110 |pmid=24043804 |pmc=3816463 |date=16 September 2013 |volume=110 |issue=44 |pages=17768–73 |bibcode=2013PNAS..11017768A |doi-access=free }}
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* {{cite report |url=https://ar.water.usgs.gov/Fayetteville_Shale/abstracts.pdf |title=Modeling the Effects of Non-Riparian Surface Water Diversions on Flow Conditions in the Little Red Watershed |last=Cothren |first=Jackson |quote=...each well requires between 3 and 7 million gallons of water for hydraulic fracturing and the number of wells is expected to grow in the future |publisher=U. S. Geological Survey, Arkansas Water Science Center Arkansas Water Resources Center, American Water Resources Association, Arkansas State Section Fayetteville Shale Symposium 2012 |access-date=16 September 2012 |page=12 }}
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* {{cite web |url=http://www.efdsystems.org/Portals/25/Hydraulic%20Fracturing%20BMPs%20White%20Paper.pdf |title=Hydraulic Fracturing: Environmentally Friendly Practices |website=Environmentally Friendly Drilling Systems |first1=John Michael |last1=Fernandez |first2=Matthew |last2=Gunter |access-date=29 December 2012 |url-status=usurped |archive-url=https://web.archive.org/web/20130527000429/http://www.efdsystems.org/Portals/25/Hydraulic%20Fracturing%20BMPs%20White%20Paper.pdf |archive-date=27 May 2013 }}
* Gallegos, T. J. and B. A. Varela (2015). [https://purl.fdlp.gov/GPO/gpo54673 Hydraulic Fracturing Distributions and Treatment Fluids, Additives, Proppants, and Water Volumes Applied to Wells Drilled in the United States from 1947 through 2010]. [U.S. Geological Survey](/source/United_States_Geological_Survey).
* Gamper-Rabindran, Shanti, ed. ''The Shale Dilemma: A Global Perspective on Fracking and Shale Development'' (U of Pittsburgh Press, 2018) [https://www.h-net.org/reviews/showrev.php?id=56406 online review]
* {{cite report |url=http://www.lexisnexis.com/store/catalog/booktemplate/productdetail.jsp?prodId=prod20232059 |title=The Legal and Regulatory Landscape of Hydraulic Fracturing |first1=J. Cullen |last1=Howe |first2=Stephen |last2=Del Percio |publisher=LexisNexis |access-date=7 May 2014 }}
* {{cite book |title=World Energy Outlook 2011 | year= 2011 | author=IEA | publisher = [OECD](/source/Organisation_for_Economic_Co-operation_and_Development) | isbn = 978-92-64-12413-4 | pages = 91, 164| author-link= International Energy Agency }}
* {{cite report |url=http://scrantontimestribune.com/waterproject/970.pdf |last=Janco |first=David F. |date=1 February 2007 |title=PADEP Determination Letter No. 970. Diminution of Snow Shoe Borough Authority Water Well No. 2; primary water source for about 1,000 homes and businesses in and around the borough; contested by Range Resources. Determination Letter acquired by the Scranton Times-Tribune via Right-To-Know Law request. |publisher=Scranton Times-Tribune |access-date=27 December 2013 |archive-url=https://web.archive.org/web/20131227233416/http://scrantontimestribune.com/waterproject/970.pdf |archive-date=27 December 2013 }}
* {{cite report |url=http://scrantontimestribune.com/waterproject/352.pdf |last=Janco |first=David F. |date=3 January 2008 |title=PADEP Determination Letter No. 352 Determination Letter acquired by the Scranton Times-Tribune via Right-To-Know Law request. Order: Atlas Miller 42 and 43 gas wells; Aug 2007 investigation; supplied temporary buffalo for two springs, ordered to permanently replace supplies |publisher=Scranton Times-Tribune |access-date=27 December 2013 |archive-url=https://web.archive.org/web/20131227234448/http://scrantontimestribune.com/waterproject/352.pdf |archive-date=27 December 2013 }}
* {{Cite journal |last1=Kassotis |first1=Christopher D. |last2=Tillitt |first2=Donald E. |last3=Davis |first3=J. Wade |last4=Hormann |first4= Annette M.|last5=Nagel |first5=Susan C. |title=Estrogen and Androgen Receptor Activities of Hydraulic Fracturing Chemicals and Surface and Ground Water in a Drilling-Dense Region |date=March 2014 | volume = 155 | issue = 3 |journal=[Endocrinology](/source/Endocrinology_(journal)) |doi=10.1210/en.2013-1697 |pmid=24424034 |pages=897–907 |doi-access=free |bibcode=2014Endoc.155..897K }}
* {{cite web | last1 = Kiparsky | first1 = Michael | last2 = Hein | first2 = Jayni Foley | title = Regulation of Hydraulic Fracturing in California: A Wastewater and Water Quality Perspective | url = https://www.law.berkeley.edu/files/ccelp/Wheeler_HydraulicFracturing_April2013.pdf | publisher = [University of California Center for Law, Energy, and the Environment](/source/University_of_California_Center_for_Law%2C_Energy%2C_and_the_Environment) | date = April 2013 | access-date = 1 May 2014 }}
* {{Cite journal|url=https://www.scientificamerican.com/article/are-fracking-wastewater-wells-poisoning-ground-beneath-our-feeth/|last=Lustgarten|first=Abrahm|title=Are Fracking Wastewater Wells Poisoning the Ground beneath Our Feet? Leaking injection wells may pose a risk{{snd}}and the science has not kept pace with the growing glut of wastewater|journal=Scientific American|date=21 June 2012|access-date=11 October 2014}}
* {{cite video | people = Rachel Maddow, Terrence Henry | title =Rachel Maddow Show: Fracking waste messes with Texas | medium = video | publisher = [MSNBC](/source/MSNBC) | date=7 August 2012 | time = 9:24 – 10:35 }}
* {{Cite journal |last1=McKenzie |first1=Lisa |last2=Witter |first2=Roxana|last3=Newman |first3=Lee |last4=Adgate |first4=John | title= Human health risk assessment of air emissions from development of unconventional natural gas resources |year=2012 |journal=Science of the Total Environment |volume=424 |pages=79–87 |doi=10.1016/j.scitotenv.2012.02.018 |pmid=22444058 |bibcode=2012ScTEn.424...79M }}
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* {{cite report |url=http://mitei.mit.edu/system/files/NaturalGas_Report.pdf |author=Moniz, Ernest J. |publisher=[Massachusetts Institute of Technology](/source/Massachusetts_Institute_of_Technology) |title=The Future of Natural Gas: An Interdisciplinary MIT Study |date=June 2011 |access-date=1 June 2012 |display-authors=etal |archive-url=https://web.archive.org/web/20130312072026/http://mitei.mit.edu/system/files/NaturalGas_Report.pdf |archive-date=12 March 2013 }}
* {{cite web |url=http://www.ohiodnr.com/Portals/11/pdf/wastewater-fact-sheet.pdf |title=Waste water (flowback)from hydraulic fracturing |publisher=[Ohio Department of Natural Resources](/source/Ohio_Department_of_Natural_Resources) |access-date=29 June 2013 |archive-url=https://web.archive.org/web/20120508195902/http://ohiodnr.com/Portals/11/pdf/wastewater-fact-sheet.pdf |archive-date=8 May 2012 }}
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* {{cite journal|last=Ridlington|first=Elizabeth|author2=John Rumpler|title=Fracking by the numbers|journal=Environment America|date=3 October 2013|url=http://www.environmentamerica.org/reports/ame/fracking-numbers}}
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* {{cite news |url=https://www.theatlantic.com/national/archive/2014/12/the-alarming-research-behind-new-yorks-fracking-ban/383868/ |title=The Alarming Research Behind New York's Fracking Ban – an analysis of the findings in Governor Andrew Cuomo's 184-page review of hydraulic fracturing |author=Nicholas St. Fleur |date=19 December 2014 |work=The Atlantic |access-date=21 December 2014 }}
* {{cite web |title=DISH, Texas Exposure Investigation |url=https://www.dshs.state.tx.us/epitox/consults/dish_ei_2010.pdf |publisher=Texas DSHS |access-date=27 March 2013 }}
* {{cite web|url= https://www.epa.gov/hfstudy/hydraulic-fracturing-water-cycle|title= The Hydraulic Fracturing Water Cycle|date= 16 March 2014|publisher= [EPA](/source/United_States_Environmental_Protection_Agency)|access-date= 10 October 2014|archive-date= 28 April 2020|archive-url= https://web.archive.org/web/20200428235022/https://www.epa.gov/hfstudy/hydraulic-fracturing-water-cycle|url-status= live}}
* {{cite web |url= https://www.usgs.gov/faq/?q=categories/10132/3830 |title= How is hydraulic fracturing related to earthquakes and tremors? |publisher= [USGS](/source/United_States_Geological_Survey) |access-date= 4 November 2012 |archive-url= https://web.archive.org/web/20141019024105/http://www.usgs.gov/faq/?q=categories%2F10132%2F3830 |archive-date= 19 October 2014 }}
* {{cite journal |last= Weinhold |first= Bob |date= 19 September 2012 |title= Unknown Quantity: Regulating Radionuclides in Tap Water |quote = Examples of human activities that may lead to radionuclide exposure include mining, milling, and processing of radioactive substances; wastewater releases from the hydraulic fracturing of oil and natural gas wells... Mining and hydraulic fracturing, or 'fracking', can concentrate levels of uranium (as well as radium, radon, and thorium) in wastewater... | journal= Environmental Health Perspectives |volume= 120 |issue= 9 |pages= A350–56 |doi= 10.1289/ehp.120-a350 |doi-broken-date= 2 January 2026 |pmid=23487846 |pmc= 3440123 }}
{{refend}}

==External links==
{{commons category}}
{{wikinews|Disposal of fracking wastewater poses potential environmental problems}}
{{wiktionary}}
* [https://udayton.edu/directory/law/documents/watson/blake_watson_hydraulic_fracturing_primer.pdf Hydraulic Fracturing Litigation Summary] (22 April 2021)
* Science blogs by the [National Institute for Occupational Safety and Health](/source/National_Institute_for_Occupational_Safety_and_Health) [https://blogs.cdc.gov/niosh-science-blog/category/hydraulic-fracturing/ on Fracking].

{{Shale gas|technology=yes}}
{{Petroleum industry}}
{{Authority control}}

Category:1947 introductions
Category:Hydraulic fracturing
Category:Unconventional oil

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Adapted from the Wikipedia article [Fracking](https://en.wikipedia.org/wiki/Fracking) by Wikipedia contributors ([contributor history](https://en.wikipedia.org/wiki/Fracking?action=history)). Available under [Creative Commons Attribution-ShareAlike 4.0 International](https://creativecommons.org/licenses/by-sa/4.0/). Changes may have been made.