Schematic depiction of hydraulic fracturing for shale gas
|Main technologies or sub-processes||Fluid pressure|
|Product(s)||Natural gas, petroleum|
|Inventor||Floyd Farris, Joseph B. Clark (Stanolind Oil and Gas Corporation)|
|Year of invention||1947|
Shale gas drilling rig near Alvarado, Texas
Hydraulic fracturing (also hydrofracturing, hydrofracking, fracking, or fraccing) is a well-stimulation technique in which rock is fractured by a pressurized liquid. The process involves the high-pressure injection of 'fracking fluid' (primarily water, containing sand or other proppants suspended with the aid of thickening agents) into a wellbore to create cracks in the deep-rock formations through which natural gas, petroleum, and brine will flow more freely. When the hydraulic pressure is removed from the well, small grains of hydraulic fracturing proppants (either sand or aluminium oxide) hold the fractures open.
Hydraulic fracturing began as an experiment in 1947, and the first commercially successful application followed in 1950. 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. Such treatment is generally necessary to achieve adequate flow rates in shale gas, tight gas, tight oil, and coal seam gas wells. Some hydraulic fractures can form naturally in certain veins or dikes.
Hydraulic fracturing is highly controversial in many countries. Its proponents advocate the economic benefits of more extensively accessible hydrocarbons. However, opponents argue that these are out-weighed by the potential environmental impacts, which include risks of ground and surface water contamination, air and noise pollution, and potentially triggering earthquakes, along with the consequential hazards to public health and the environment.
Increases in seismic activity following hydraulic fracturing along dormant or previously unknown faults are sometimes caused by the deep-injection disposal of hydraulic fracturing flowback (a byproduct of hydraulically fractured wells), and produced formation brine (a byproduct of both fractured and nonfractured oil and gas wells). For these reasons, hydraulic fracturing is under international scrutiny, restricted in some countries, and banned altogether in others. Some countries have banned the practice or put moratoria in place, while others have adopted an approach involving tight regulation. The European Union is drafting regulations that would permit controlled application of hydraulic fracturing.
- 1 Geology
- 2 History
- 3 Process
- 4 Uses
- 5 Economic effects
- 6 Public debate
- 7 Health risks
- 8 Environmental impacts
- 9 Regulations
- 10 See also
- 11 References
- 12 External links
- 13 Further reading
Fracturing rocks at great depth frequently becomes suppressed by 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) fractures which require the walls of the fracture to move against this pressure. Fracturing occurs when effective stress is overcome by the pressure of fluids within the rock. The minimum principal stress becomes tensile and exceeds the tensile strength of the material. Fractures formed in this way are generally oriented in a plane perpendicular to the minimum principal stress, and for this reason, hydraulic fractures in well bores can be used to determine the orientation of stresses. In natural examples, such as dikes or vein-filled fractures, the orientations can be used to infer past states of stress.
Most mineral vein systems are a result of repeated natural fracturing during periods of relatively high pore fluid pressure. The impact 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. 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 water to be expelled from fluid-filled fractures. This process is referred to as "seismic pumping".
Minor intrusions in the upper part of the crust, such as dikes, propagate in the form of fluid-filled cracks. In such cases, the fluid is magma. In sedimentary rocks with a significant water content, fluid at fracture tip will be steam.
Fracturing as a method to stimulate shallow, hard rock oil wells dates back to the 1860s. Dynamite or nitroglycerin detonations were used to increase oil and natural gas production from petroleum bearing formations. On 25 April 1865, Civil War veteran Col. Edward A. L. Roberts received a patent for an "exploding torpedo". It was employed in Pennsylvania, New York, Kentucky, and West Virginia using liquid and also, later, solidified nitroglycerin. 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, fractures would not close completely resulting in further productivity increase.
Oil and gas wells
The relationship between well performance and treatment pressures was studied by Floyd Farris of Stanolind Oil and Gas Corporation. This study was the basis of the first hydraulic fracturing experiment, conducted in 1947 at the Hugoton gas field in Grant County of southwestern Kansas by Stanolind. For the well treatment, 1,000 US gallons (3,800 l; 830 imp gal) of gelled gasoline (essentially napalm) and sand from the Arkansas River was injected into the gas-producing limestone formation at 2,400 feet (730 m). The experiment was not very successful as 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 exclusive license was granted to the Halliburton Oil Well Cementing Company. On 17 March 1949, Halliburton performed the first two commercial hydraulic fracturing treatments in Stephens County, Oklahoma, and Archer County, Texas. Since then, hydraulic fracturing has been used to stimulate approximately one million oil and gas wells 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.
In the Soviet Union, the first hydraulic proppant fracturing was carried out in 1952. Other countries in Europe and Northern Africa subsequently employed hydraulic fracturing techniques including Norway, Poland, Czechoslovakia, Yugoslavia, Hungary, Austria, France, Italy, Bulgaria, Romania, Turkey, Tunisia, and Algeria.
Massive hydraulic fracturing (also known as high-volume hydraulic fracturing) is a technique first applied by Pan American Petroleum in Stephens County, Oklahoma, USA 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.
American geologists gradually became aware that there were huge volumes of gas-saturated sandstones with permeability too low (generally less than 0.1 millidarcy) to recover the gas economically. Starting in 1973, massive hydraulic fracturing was used in thousands of gas wells in the San Juan Basin, Denver Basin, the Piceance Basin, and the 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, and Cotton Valley Sandstone.
Massive hydraulic fracturing quickly spread in the late 1970s to western Canada, Rotliegend and Carboniferous gas-bearing sandstones in Germany, Netherlands (onshore and offshore gas fields), and the United Kingdom in the North Sea.
Horizontal oil or gas wells were unusual until the late 1980s. Then, operators in Texas began completing thousands of oil wells by drilling horizontally in the Austin Chalk, and giving massive slickwater hydraulic fracturing treatments to the wellbores. Horizontal wells proved much more effective than vertical wells in producing oil from tight chalk; sedimentary beds are usually nearly horizontal, so horizontal wells have much larger contact areas with the target formation.
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 and Cleveland Shale, using relatively small fracs. The frac jobs generally increased production, especially from lower-yielding wells.
In 1976, the United States government started the Eastern Gas Shales Project, which included numerous public-private hydraulic fracturing demonstration projects. During the same period, the Gas Research Institute, a gas industry research consortium, received approval for research and funding from the Federal Energy Regulatory Commission.
In 1997, taking the slickwater fracturing technique used in East Texas by Union Pacific Resources (now part of Anadarko Petroleum Corporation), Mitchell Energy (now part of Devon Energy), applied the technique in the Barnett Shale of north Texas. This made gas extraction widely economical in the Barnett Shale, and was later applied to other shales. George P. Mitchell has been called the "father of fracking" because of his role in applying it in shales. The first horizontal well in the 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.
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.
According to the United States Environmental Protection Agency (EPA), hydraulic fracturing is a process to stimulate a natural gas, oil, or geothermal well to maximize extraction. The EPA defines the broader process to include acquisition of source water, well construction, well stimulation, and waste disposal.
A hydraulic fracture is formed by pumping 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. 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 square foot, or bars. 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 relevant to the distance from the well. Operators typically try to maintain "fracture width", or slow its decline following treatment, by introducing a proppant into the injected fluid – 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.
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.
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 wellbores, and the zones to be fractured are accessed by perforating the casing at those locations.
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[clarification needed], a chemical additive unit (used to accurately monitor chemical addition), low-pressure flexible hoses, and many gauges and meters for flow rate, fluid density, and treating pressure. Chemical additives are typically 0.5% percent of the total fluid volume. Fracturing equipment operates over a range of pressures and injection rates, and can reach up to 100 megapascals (15,000 psi) and 265 litres per second (9.4 cu ft/s) (100 barrels per minute).
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.
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 1,500 to 5,000 feet (460 to 1,520 m) in the Barnett Shale basin in Texas, and up to 10,000 feet (3,000 m) in the Bakken formation in North Dakota. In contrast, a vertical well only accesses the thickness of the rock layer, typically 50–300 feet (15–91 m). 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.
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 – high-rate and high-viscosity. High-viscosity fracturing tends to cause large dominant fractures, while high-rate (slickwater) fracturing causes small spread-out micro-fractures.
Fluid is typically a slurry of water, proppant, and chemical additives. Additionally, gels, foams, and compressed gases, including nitrogen, 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%. However, fracturing fluids have been developed using liquefied petroleum gas (LPG) and propane in which water is unnecessary.
The proppant is a granular material that prevents the created fractures from closing after the fracturing treatment. Types of proppant include silica sand, resin-coated sand, 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.
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, pH, various rheological factors, and others.
Water is mixed with sand and chemicals to create fracking fluid. Approximately 40,000 gallons of chemicals are used per fracturing. A typical fracture treatment uses between 3 and 12 additive chemicals. Although there may be unconventional fracturing fluids, typical chemical additives can include one or more of the following:
- Acids—hydrochloric acid or acetic acid is used in the pre-fracturing stage for cleaning the perforations and initiating fissure in the near-wellbore rock.
- Sodium chloride (salt)—delays breakdown of gel polymer chains.
- 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.
- Ethylene glycol—prevents formation of scale deposits in the pipe.
- Borate salts—used for maintaining fluid viscosity during the temperature increase.
- Sodium and potassium carbonates—used for maintaining effectiveness of crosslinkers.
- Anaerobic, Biocide, BIO—Glutaraldehyde used as disinfectant of the water (bacteria elimination).
- Guar gum and other water-soluble gelling agents—increases viscosity of the fracturing fluid to deliver proppant into the formation more efficiently.
- Citric acid—used for corrosion prevention.
- Isopropanol—used to winterize the chemicals to ensure it doesn't freeze.
The most common chemical used for hydraulic fracturing in the United States in 2005–2009 was methanol, while some other most widely used chemicals were isopropyl alcohol, 2-butoxyethanol, and ethylene glycol.
Typical fluid types are:
- Conventional linear gels. These gels are cellulose derivative (carboxymethyl cellulose, hydroxyethyl cellulose, carboxymethyl hydroxyethyl cellulose, hydroxypropyl cellulose, hydroxyethyl methyl cellulose), guar or its derivatives (hydroxypropyl guar, carboxymethyl hydroxypropyl guar), mixed with other chemicals.[clarification needed]
- Borate-crosslinked fluids. These are guar-based fluids cross-linked with boron ions (from aqueous borax/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, chromium, antimony, 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.[clarification needed]
- Aluminium phosphate-ester oil gels. Aluminium phosphate and 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. As the fracturing process proceeds, viscosity-reducing agents such as oxidizers and enzyme breakers are sometimes added to the fracturing fluid to deactivate the gelling agents and encourage flowback. Such oxidizer 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 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. 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.
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.
Injection of radioactive tracers along with the fracturing fluid is sometimes used to determine the injection profile and location of created fractures. Radiotracers are selected to have the readily detectable radiation, appropriate chemical properties, and a half life and toxicity level that will minimize initial and residual contamination. Radioactive isotopes chemically bonded to glass (sand) and/or resin beads may also be injected to track fractures. 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. Radiotracers such as Tc-99m and I-131 are also used to measure flow rates. The Nuclear Regulatory Commission publishes guidelines which list a wide range of radioactive materials in solid, liquid and gaseous forms that may be used as tracers and limit the amount that may be used per injection and per well of each radionuclide.
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 fracking fluid different parts of the well use as well as how much natural gas they collect.
For more advanced applications, microseismic monitoring is sometimes used to estimate the size and orientation of induced fractures. Microseismic activity is measured by placing an array of geophones 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 arrays deployed on the surface or down a well provide another technology for monitoring strain
Microseismic mapping is very similar geophysically to seismology. In earthquake seismology, seismometers scattered on or near the surface of the earth record S-waves and P-waves that are released during an earthquake event. This allows for motion[clarification needed] 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.[clarification needed] Tensile stresses are generated ahead of the fracture's tip, generating large amounts of shear stress. The increases in pore water pressure and in formation stress combine and affect weaknesses near the hydraulic fracture, like natural fractures, joints, and bedding planes.
Different methods have different location errors[clarification needed] 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 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[clarification needed] 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. 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 than accurately predicts well performance.
Since the early 2000s, advances in drilling and completion technology have made horizontal wellbores much[clarification needed] 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.
In North America, shale reservoirs such as the Bakken, Barnett, Montney, Haynesville, Marcellus, and most recently the Eagle Ford, Niobrara and Utica shales are drilled horizontally through the producing interval(s), completed and fractured. 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".
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 is used to perforate 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.
The wellbore for the sliding sleeve[clarification needed] 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 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.
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.
Hydraulic fracturing is used to increase the rate at which fluids, such as petroleum, water, or natural gas can be recovered from subterranean natural reservoirs. Reservoirs are typically porous sandstones, limestones or dolomite rocks, but also include "unconventional reservoirs" such as shale rock or coal beds. Hydraulic fracturing enables the extraction of natural gas and oil from rock formations deep below the earth's surface (generally 2,000–6,000 m (5,000–20,000 ft)), which is greatly below typical groundwater reservoir levels. At such depth, there may be insufficient permeability 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 microdarcy to nanodarcy range. 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. 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.
- To stimulate groundwater wells
- To precondition or induce rock cave-ins mining
- As a means of enhancing waste remediation, usually hydrocarbon waste or spills
- To dispose waste by injection deep into rock
- To measure stress in the Earth
- For electricity generation in enhanced geothermal systems
- To increase injection rates for geologic sequestration of CO2
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 US, Australia, and South Africa.
||The examples and perspective in this section deal primarily with the United States and do not represent a worldwide view of the subject. (April 2014)|
||This section may be too long and excessively detailed. (May 2014)|
Hydraulic fracturing has been seen as one of the key methods of extracting unconventional oil and unconventional gas resources. According to the International Energy Agency, the remaining technically recoverable resources of shale gas are estimated to amount to 208 trillion cubic metres (208,000 km3), tight gas to 76 trillion cubic metres (76,000 km3), and coalbed methane to 47 trillion cubic metres (47,000 km3). 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.
The National Petroleum Council estimates that hydraulic fracturing will eventually account for nearly 70% of natural gas development in North America. Hydraulic fracturing and horizontal drilling apply the latest technologies and make it commercially viable to recover shale gas and oil. In the United States, 45% of domestic natural gas production and 17% of oil production would be lost within 5 years without usage of hydraulic fracturing.
U.S.-based refineries have gained a competitive edge with their access to relatively inexpensive shale oil and Canadian crude. The U.S. is exporting more refined petroleum products, and also more liquified petroleum gas (LP gas). LP gas is produced from hydrocarbons called natural gas liquids, released by the hydraulic fracturing of petroliferous shale, in a variety of shale gas that's relatively easy to export. Propane, for example, costs around $620 a ton in the U.S. compared with more than $1,000 a ton in China, as of early 2014. Japan, for instance, is importing extra LP gas to fuel power plants, replacing idled nuclear plants. Trafigura Beheer BV, the third-largest independent trader of crude oil and refined products, said at the start of 2014 that "growth in U.S. shale production has turned the distillates market on its head."
Some studies call into question the claim that what has been called the "shale gas revolution" has a significant macro-economic impact. A study released in the beginning of 2014 by the IDDRI concluded the contrary. It states that, on the long-term as well as on the short-run, the "shale gas revolution" due to hydraulic fracturing in the United States has had very little impact on economic growth and competitiveness. The same report concludes that in Europe, using hydraulic fracturing would have very little advantage in terms of competitiveness and energy security. Indeed, for the period 2030-2035, shale gas is estimated to cover 3 to 10% of EU projected energy demand, which is not enough to have a significant impact on energetic independence and competitiveness.
Hydrofracked shale oil and gas has the potential to alter the geography of energy production in the US.[better source needed] In the short run, in counties with hydrofracturing employment in the oil and gas sector more than doubled in the last 10 years, with spill-overs in local transport-, construction but also manufacturing sectors.[better source needed] The manufacturing sector benefits from lower energy prices, giving the US manufacturing sector a competitive edge. On average, natural gas prices have decreased by more than 30% in counties above shale deposits compared to the rest of the US. Some research has highlighted the negative effects on house prices for properties in the direct vicinity of fracturing wells. Local house prices in Pennsylvania decrease if the property is close to a hydrofracking gas well and is not connected to city water, suggesting that the concerns of ground water pollution are priced by markets.
Politics and public policy
An anti-fracking movement has emerged both internationally with involvement of international environmental organizations and nations such as France and locally in affected areas such as Balcombe in Sussex where the Balcombe drilling protest was in progress during mid-2013. The considerable opposition against hydraulic fracturing activities in local townships in the United States has led companies to adopt a variety of public relations measures to reassure the public, including the employment of former military personnel with training in psychological warfare operations. According to Matt Pitzarella, the communications director at 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.
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. Though usually nonviolent, some protestors use violence and intimidation. 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, before shouting profanities at the site and fleeing the scene. In Washington County, Pennsylvania, a contractor working on a gas pipeline found a 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.
In 2014 a number of European officials provided circumstantial evidence that Eastern European protests against fracking may be sponsored by Gazprom, Russia's state-controlled gas company. Russian officials have on numerous occasions warned Europe that fracking "poses a huge environmental problem".
Josh Fox's 2010 Academy Award nominated film Gasland became a center of opposition to hydraulic fracturing of shale. The movie presented problems with ground water contamination near well sites in Pennsylvania, Wyoming, and Colorado. Energy in Depth, an oil and gas industry lobbying group, called the film's facts into question. In response, a rebuttal of Energy in Depth's claims of inaccuracy was posted on Gasland's website.
The Director of the Colorado Oil and Gas Conservation Commission (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. Exxon Mobil, Chevron Corporation and ConocoPhillips aired advertisements during 2011 and 2012 that claimed to describe the economic and environmental benefits of natural gas and argue that hydraulic fracturing was safe.
The film Promised Land, starring Matt Damon, takes on hydraulic fracturing. The gas industry is making plans to try to counter the film's criticisms of hydraulic fracturing with informational flyers, and Twitter and Facebook posts.
In January 2013 Northern Irish journalist and filmmaker Phelim McAleer released a crowdfunded documentary called FrackNation as a response to the statements made by Fox in Gasland. FrackNation premiered on Mark Cuban's AXS TV. The premiere corresponded with the release of Promised Land.
In April 2013, Josh Fox released Gasland 2, a documentary that states that the gas industry's portrayal of natural gas as a clean and safe alternative to oil is 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.
In 2014, Vido 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 fracking in their advertising.
In 2015, the Canadian documentary film Fractured Land had its world premiere at the Hot Docs Canadian International Documentary Festival.
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. Several organizations, researchers, and media outlets have reported difficulty in conducting and reporting the results of studies on hydraulic fracturing due to industry and governmental pressure, and expressed concern over possible censoring of environmental reports. There is a need for more research into the environmental and health effects of the technique.
There is concern over the possible adverse public health implications of hydraulic fracturing activity. 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." 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.
In June 2014 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. 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, 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 (ie 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.":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. This led to a series of recommendations in 2014 to mitigate these concerns. 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.
The environmental impacts of hydraulic fracturing include air emissions and climate change, high water consumption, water contamination, land use, risk of earthquakes, noise pollution, and health effects on humans. Air emissions are primarily methane that escapes from wells, along with industrial emissions from equipment used in the extraction process. Modern UK and EU regulation requires zero emissions of methane, a potent greenhouse gas. Escape of methane is a bigger problem in older wells than in ones built under more recent EU legislation.
Hydraulic fracturing uses between 1.2 and 3.5 million US gallons (4,500 and 13,200 m3) of water per well, with large projects using up to 5 million US gallons (19,000 m3). Additional water is used when wells are refractured. An average well requires 3 to 8 million US gallons (11,000 to 30,000 m3) of water over its lifetime. According to the 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. Surface water may be contaminated through spillage and improperly built and maintained waste pits, and ground water can be contaminated if the fluid is able to escape the formation being fractured (through, for example, abandoned wells) or by produced water (the returning fluids, which also contain dissolved constituents such as minerals and brine waters). Produced water is managed by underground injection, municipal and commercial wastewater treatment and discharge, self‐contained systems at well sites or fields, and recycling to fracture future wells. Typically less than half of the produced water used to fracture the formation is recovered.
About 3.6 hectares (8.9 acres) of land is needed per each drill pad for surface installations. Well pad and supporting structure construction significantly fragments landscapes which likely has negative effects on wildlife. These sites need to be remediated after wells are exhausted. 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. Research is underway to determine if human health has been affected by air and 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.
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.
Hydraulic fracturing sometimes causes induced seismicity or earthquakes. The magnitude of these events is usually too small to be detected at the surface, although tremors attributed to fluid injection into disposal wells have been large enough to have often been felt by people, and to have caused property damage and possibly injuries.
Microseismic events are often used to map the horizontal and vertical extent of the fracturing. 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.
Countries using or considering use of hydraulic fracturing have implemented different regulations, including developing federal and regional legislation, and local zoning limitations. In 2011, after public pressure France became the first nation to ban hydraulic fracturing, based on the precautionary principle as well as the principle of preventive and corrective action of environmental hazards. The ban was upheld by an October 2013 ruling of the Constitutional Council. Some other countries such as Scotland have placed a temporary moratorium on the practice due to public health concerns and strong public opposition. Countries like the United Kingdom and South Africa have lifted their bans, choosing to focus on regulation instead of outright prohibition. Germany has announced draft regulations that would allow using hydraulic fracturing for the exploitation of shale gas deposits with the exception of wetland areas. In China, regulation on shale gas still faces hurdles, as it has complex interrelations with other regulatory regimes, especially trade.
The European Union has adopted a recommendation for minimum principles for using high-volume hydraulic fracturing. Its regulatory regime requires full disclosure of all additives. 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. Hydraulic fracturing is excluded from the Safe Drinking Water Act's underground injection control's regulation, except when diesel fuel is used. The EPA assures surveillance of the issuance of drilling permits when diesel fuel is employed.
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.
- Dayne Pratzky
- Directional drilling
- Environmental concerns with electricity generation
- Environmental impact of hydraulic fracturing
- Environmental impact of petroleum
- Environmental impact of the oil shale industry
- Drew Hutton
- Hydraulic fracturing by country
- Hydraulic fracturing in the United States
- Hydraulic fracturing in the United Kingdom
- In-situ leach
- Stranded asset
- Luca Gandossi, Joint Research Centre, Institute for Energy and Transport (2013). An overview of hydraulic fracturing and other formation stimulation technologies for shale gas production (PDF). Scientific and Technical Research series. (Report) (European Commission Luxembourg: Publications Office of the European Union). Retrieved 29 May 2015.
- King, George E (2012), Hydraulic fracturing 101 (PDF), Society of Petroleum Engineers, Paper 152596
- Staff. "State by state maps of hydraulic fracturing in US.". Fractracker.org. Retrieved 19 October 2013.
- Charlez, Philippe A. (1997). Rock Mechanics: Petroleum Applications. Paris: Editions Technip. p. 239. ISBN 9782710805861. Retrieved 2012-05-14.
- Blundell D., (2005). "Processes of tectonism, magmatism and mineralization: Lessons from Europe". Ore Geology Reviews 27: 340.
- IEA (29 May 2012). Golden Rules for a Golden Age of Gas. World Energy Outlook Special Report on Unconventional Gas (PDF). OECD. pp. 18–27.
- Hillard Huntington et al. EMF 26: Changing the Game? Emissions and Market Implications of New Natural Gas Supplies Report. Stanford University. Energy Modeling Forum, 2013.
- Brown, Valerie J. (February 2007). "Industry Issues: Putting the Heat on Gas". Environmental Health Perspectives (US National Institute of Environmental Health Sciences) 115 (2): A76. doi:10.1289/ehp.115-a76. PMC 1817691. PMID 17384744. Retrieved 2012-05-01.
- V. J. Brown (February 2014). "Radionuclides in Fracking Wastewater: Managing a Toxic Blend". Environmental Health Perspectives. p. A50. Retrieved 27 May 2015.
- Kim, Won-Young 'Induced seismicity associated with fluid injection into a deep well in Youngstown, Ohio', Journal of Geophysical Research-Solid Earth
- US Geological Survey, Produced water, overview, accessed 8 Nov. 2014.
- Jared Metzker (7 August 2013). "Govt, Energy Industry Accused of Suppressing Fracking Dangers". Inter Press Service. Retrieved 28 December 2013.
- Patel, Tara (31 March 2011). "The French Public Says No to 'Le Fracking'". Bloomberg Businessweek. Retrieved 22 February 2012.
- Patel, Tara (4 October 2011). "France to Keep Fracking Ban to Protect Environment, Sarkozy Says". Bloomberg Businessweek. Retrieved 22 February 2012.
- "Commission recommendation on minimum principles for the exploration and production of hydrocarbons (such as shale gas) using high-volume hydraulic fracturing (2014/70/EU)". Official Journal of the European Union. 22 January 2014. Retrieved 13 March 2014.
- Fjaer, E. (2008). "Mechanics of hydraulic fracturing". Petroleum related rock mechanics. Developments in petroleum science (2nd ed.). Elsevier. p. 369. ISBN 978-0-444-50260-5. Retrieved 2012-05-14.
- Price, N. J.; Cosgrove, J. W. (1990). Analysis of geological structures. Cambridge University Press. pp. 30–33. ISBN 978-0-521-31958-4. Retrieved 5 November 2011.
- Manthei, G.; Eisenblätter, J.; Kamlot, P. (2003). "Stress measurement in salt mines using a special hydraulic fracturing borehole tool". In Natau, Fecker & Pimentel. Geotechnical Measurements and Modelling (PDF). pp. 355–360. ISBN 90-5809-603-3. Retrieved 6 March 2012.
- Zoback, M.D. (2007). Reservoir geomechanics. Cambridge University Press. p. 18. ISBN 9780521146197. Retrieved 6 March 2012.
- Laubach, S. E.; Reed, R. M.; Olson, J. E.; Lander, R. H.; Bonnell, L. M. (2004). "Coevolution of crack-seal texture and fracture porosity in sedimentary rocks: cathodoluminescence observations of regional fractures". Journal of Structural Geology (Elsevier) 26 (5): 967–982. Bibcode:2004JSG....26..967L. doi:10.1016/j.jsg.2003.08.019. Retrieved 5 November 2011.
- Sibson, R. H.; Moore, J.; Rankin, A. H. (1975). "Seismic pumping--a hydrothermal fluid transport mechanism". Journal of the Geological Society (London: Geological Society) 131 (6): 653–659. doi:10.1144/gsjgs.131.6.0653. (subscription required). Retrieved 5 November 2011.
- Gill, R. (2010). Igneous rocks and processes: a practical guide. John Wiley and Sons. p. 102. ISBN 978-1-4443-3065-6. Retrieved 5 November 2011.
- "Shooters – A "Fracking" History". American Oil & Gas Historical Society. Retrieved 12 October 2014.
- "Acid fracturing". Society of Petroleum Engineers. Retrieved 12 October 2014.
- Montgomery, Carl T.; Smith, Michael B. (December 2010). "Hydraulic fracturing. History of an enduring technology" (PDF). JPT Online (Society of Petroleum Engineers): 26–41. Retrieved 13 May 2012.
- Energy Institute (February 2012). Fact-Based Regulation for Environmental Protection in Shale Gas Development (PDF) (Report). University of Texas at Austin. Retrieved 29 February 2012.
- A. J. Stark, A. Settari, J. R. Jones, Analysis of Hydraulic Fracturing of High Permeability Gas Wells to Reduce Non-darcy Skin Effects, Petroleum Society of Canada, Annual Technical Meeting, 8 - 10 Jun 1998, Calgary, Alberta. Archived 16 October 2013 at the Wayback Machine.
- Mader, Detlef (1989). Hydraulic Proppant Fracturing and Gravel Packing. Elsevier. pp. 173–174; 202. ISBN 9780444873521.
- 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, p.233-252.
- 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, 1977) 293-300.
- 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, 1977) 285-291.
- C.E Bell and others, Effective diverting in horizontal wells in the Austin Chalk, Society of Petroleum Engineers conference paper, 1993. Archived 5 October 2013 at the Wayback Machine.
- Robbins K. (2013). Awakening the Slumbering Giant: How Horizontal Drilling Technology Brought the Endangered Species Act to Bear on Hydraulic Fracturing. Case Western Reserve Law Review.
- E. O. Ray, Shale development in eastern Kentucky, US Energy Research and Development Administration, 1976.
- US Dept. of Energy, How is shale gas produced?, Apr. 2013.
- United States National Research Council, Committee to Review the Gas Research Institute's Research, Development and Demonstration Program, Gas Research Institute (1989). A review of the management of the Gas Research Institute. National Academies. p. ?.
- "US Government Role in Shale Gas Fracking: An Overview"
- SPE production & operations 20. Society of Petroleum Engineers. 2005. p. 87.
- The Breakthrough Institute. Interview with Dan Steward, former Mitchell Energy Vice President. December 2011.
- Zuckerman, Gregory. "How fracking billionaires built their empires". Quartz. The Atlantic Media Company. Retrieved 15 November 2013.
- Wasley, Andrew (1 March 2013) On the frontline of Poland's fracking rush The Guardian, Retrieved 3 March 2013
- (7 August 2012) JKX Awards Fracking Contract for Ukrainian Prospect Natural Gas Europe, Retrieved 3 March 2013
- (18 February 2013) Turkey's shale gas hopes draw growing interest Reuters, Retrieved 3 March 2013
- "Hydraulic fracturing research study" (PDF). EPA. June 2010. EPA/600/F-10/002. Retrieved 2012-12-26.
- Ground Water Protection Council; ALL Consulting (April 2009). Modern Shale Gas Development in the United States: A Primer (PDF) (Report). DOE Office of Fossil Energy and National Energy Technology Laboratory. pp. 56–66. DE-FG26-04NT15455. Retrieved 24 February 2012.
- Penny, Glenn S.; Conway, Michael W.; Lee, Wellington (June 1985). "Control and Modeling of Fluid Leakoff During Hydraulic Fracturing". Journal of Petroleum Technology (Society of Petroleum Engineers) 37 (6): 1071–1081. doi:10.2118/12486-PA. Archived from the original on 13 July 2012. Retrieved 2012-05-10.
- Arthur, J. Daniel; Bohm, Brian; Coughlin, Bobbi Jo; Layne, Mark (2008). Hydraulic Fracturing Considerations for Natural Gas Wells of the Fayetteville Shale (PDF) (Report). ALL Consulting. p. 10. Retrieved 2012-05-07.
- Chilingar, George V.; Robertson, John O.; Kumar, Sanjay (1989). Surface Operations in Petroleum Production 2. Elsevier. pp. 143–152. ISBN 9780444426772.
- Love, Adam H. (December 2005). "Fracking: The Controversy Over its Safety for the Environment". Johnson Wright, Inc. Retrieved 2012-06-10.
- "Hydraulic Fracturing". University of Colorado Law School. Retrieved 2 June 2012.
- Wan Renpu (2011). Advanced Well Completion Engineering. Gulf Professional Publishing. p. 424. ISBN 9780123858689.
- Andrews, Anthony; et al. (30 October 2009). Unconventional Gas Shales: Development, Technology, and Policy Issues (PDF) (Report). Congressional Research Service. pp. 7; 23. Retrieved 22 February 2012.
- Ram Narayan (8 August 2012). "From Food to Fracking: Guar Gum and International Regulation". RegBlog. University of Pennsylvania Law School. Retrieved 15 August 2012.
- Hartnett-White, K. (2011). "The Fracas About Fracking- Low Risk, High Reward, but the EPA is Against it" (PDF). National Review Online. Retrieved 2012-05-07.
- "Freeing Up Energy. Hydraulic Fracturing: Unlocking America's Natural Gas Resources" (PDF). American Petroleum Institute. 2010-07-19. Retrieved 2012-12-29.
- Brainard, Curtis (June 2013). "The Future of Energy". Popular Science Magazine. p. 59. Retrieved 1 January 2014.
- "CARBO ceramics". Retrieved 2011.
- "http://www.usgs.gov/newsroom/images/2015_06_30/water_use_for_fracking.jpg". www.usgs.gov. Retrieved 2015-07-03. External link in
- Central, Bobby. "Water Use Rises as Fracking Expands". Retrieved 2015-07-03.
- Dong, Linda. "What goes in and out of Hydraulic Fracturing". Dangers of Fracking. Retrieved 2015.
- Chemicals Used in Hydraulic Fracturing (PDF) (Report). Committee on Energy and Commerce U.S. House of Representatives. 18 April 2011. p. ?.
- ALL Consulting (June 2012). The Modern Practices of Hydraulic Fracturing: A Focus on Canadian Resources (PDF) (Report). Canadian Association of Petroleum Producers. Retrieved 2012-08-04.
- Reis, John C. (1976). Environmental Control in Petroleum Engineering. Gulf Professional Publishers.
- Radiation Protection and the Management of Radioactive Waste in the Oil and Gas Industry (PDF) (Report). International Atomic Energy Agency. 2003. pp. 39–40. Retrieved 20 May 2012.
Beta emitters, including 3H and 14C, 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 46Sc, 140La, 56Mn, 24Na, 124Sb, 192Ir, 99Tcm, 131I, 110Agm, 41Ar and 133Xe 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 82Br
- Jack E. Whitten, Steven R. Courtemanche, Andrea R. Jones, Richard E. Penrod, and David B. Fogl (Division of Industrial and Medical Nuclear Safety, Office of Nuclear Material Safety and Safeguards) (June 2000). "Consolidated Guidance About Materials Licenses: Program-Specific Guidance About Well Logging, Tracer, and Field Flood Study Licenses (NUREG-1556, Volume 14)". US Nuclear Regulatory Commission. Retrieved 19 April 2012.
labeled Frac Sand...Sc-46, Br-82, Ag-110m, Sb-124, Ir-192
- Bennet, Les; et al. "The Source for Hydraulic Fracture Characterization" (PDF). Oilfield Review (Schlumberger) (Winter 2005/2006): 42–57. Retrieved 2012-09-30.
- Fehler, Michael C. (1989). "Stress Control of seismicity patterns observed during hydraulic fracturing experiments at the Fenton Hill hot dry rock geothermal energy site, New Mexico". International Journal of Rock Mechanics and Mining Sciences & Geomechanics Abstracts. 3 26. doi:10.1016/0148-9062(89)91971-2. Retrieved 1 January 2014.
- Le Calvez, Joel (2007). "Real-time microseismic monitoring of hydraulic fracture treatment: A tool to improve completion and reservoir management". SPE Hydraulic Fracturing Technology Conference.
- Cipolla, Craig (2010). "Hydraulic Fracture Monitoring to Reservoir Simulation: Maximizing Value". SPE Annual Technical Conference and Exhibition. Retrieved 1 January 2014.
- Seale, Rocky (July–August 2007). "Open hole completion systems enables multi-stage fracturing and stimulation along horizontal wellbores" (PDF). Drilling Contractor (Fracturing stimulation ed.). Retrieved 1 October 2009.
- "Completion Technologies". EERC. Retrieved 2012-09-30.
- "Energy from Shale". 2011.
- Mooney, Chris (2011). "The Truth About Fracking". Scientific American 305 (305): 80–85. Bibcode:2011SciAm.305d..80M. doi:10.1038/scientificamerican1111-80.
- "The Barnett Shale" (PDF). North Keller Neighbors Together. Retrieved 2012-05-14.
- David Wethe (19 January 2012). "Like Fracking? You'll Love 'Super Fracking'". Businessweek. Retrieved 22 January 2012.
- "Production Decline of a Natural Gas Well Over Time". Geology.com. The Geology Society of America. 3 January 2012. Retrieved 4 March 2012.
- Economides, Michael J. (2000). Reservoir stimulation. J. Wiley. p. P-2. ISBN 9780471491927.
- Gidley, John L. (1989). Recent Advances in Hydraulic Fracturing. SPE Monograph 12. SPE. p. ?. ISBN 9781555630201.
- Ching H. Yew (1997). Mechanics of Hydraulic Fracturing. Gulf Professional Publishing. p. ?. ISBN 9780884154747.
- Banks, David; Odling, N. E.; Skarphagen, H.; Rohr-Torp, E. (May 1996). "Permeability and stress in crystalline rocks". Terra Nova 8 (3): 223–235. doi:10.1111/j.1365-3121.1996.tb00751.x.
- Brown, Edwin Thomas (2007) . Block Caving Geomechanics (2nd ed.). Indooroopilly, Queensland: Julius Kruttschnitt Mineral Research Centre, UQ. ISBN 978-0-9803622-0-6. Retrieved 2012-05-14.
- Frank, U.; Barkley, N. (February 1995). "Soil Remediation: Application of Innovative and Standard Technologies". Journal of Hazardous Materials 40 (2): 191–201. doi:10.1016/0304-3894(94)00069-S. ISSN 0304-3894.
|contribution=ignored (help) (subscription required)
- Bell, Frederic Gladstone (2004). Engineering Geology and Construction. Taylor & Francis. p. 670. ISBN 9780415259392.
- Aamodt, R. Lee; Kuriyagawa, Michio (1983). "Measurement of Instantaneous Shut-In Pressure in Crystalline Rock". Hydraulic fracturing stress measurements. National Academies. p. 139.
- "Geothermal Technologies Program: How an Enhanced Geothermal System Works". eere.energy.gov. 2011-02-16. Retrieved 2011-11-02.
- Miller, Bruce G. (2005). Coal Energy Systems. Sustainable World Series. Academic Press. p. 380. ISBN 9780124974517.
- Waltz, James; Decker, Tim L (1981), "Hydro-fracturing offers many benefits", Johnson Driller's Journal (2nd quarter): 4–9
- Williamson, WH (1982), "The use of hydraulic techniques to improve the yield of bores in fractured rocks", Groundwater in Fractured Rock, Conference Series (5), Australian Water Resources Council
- Less, C; Andersen, N (Feb 1994), "Hydrofracture: state of the art in South Africa", Applied Hydrogeology: 59–63
- National Petroleum Council, Prudent Development: Realizing the Potential of North America’s Abundant Natural Gas and Oil Resources, 15 September 2011.
- IHS Global Insight, Measuring the Economic and Energy Impacts of Proposals to Regulate Hydraulic Fracturing, 2009.
- Asian Refiners Get Squeezed by U.S. Energy Boom, Wall Street Journal, 1 January 2014
- Spencer T, Sartor O, Mathieu M "Unconventional wisdom: an economic analysis of US shale gas and implications for the EU", IDDRI, Paris, France, February 2014
- Fracking Growth - Estimating the Economic Impact of Shale Oil and Gas Development in the US, Fetzer, Thiemo (2014)
- Dutch Disease or Agglomeration? The Local Economic Effects of Natural Resource Booms in Modern America, Alcott and Kenniston (2013)
- "The housing market impacts of shale gas development", by Lucija Muehlenbachs, Elisheba Spiller and Christopher Timmins. NBER Working Paper 19796, January 2014.
- Jan Goodey (1 August 2013). "The UK's anti fracking movement is growing". The Ecologist. Retrieved July 29, 2013.
- Javers, Eamon (8 Nov 2011). "Oil Executive: Military-Style 'Psy Ops' Experience Applied". CNBC.
- Phillips, Susan (9 Nov 2011). "'We're Dealing with an Insurgency,' says Energy Company Exec of Fracking Foes". National Public Radio.
- Palmer, Mike (27 March 2013). "Oil-gas boom spawns Harrison safety talks". Times Leader. Retrieved 27 March 2013.
- "Shots fired at W. Pa. gas drilling site". Philadelphia Inquirer. 12 March 2013. Retrieved 27 March 2013.
- Detrow, Scott (15 August 2012). "Pipe Bomb Found Near Allegheny County Pipeline". NPR. Retrieved 27 March 2013.
- Andrew Higgins (2014-11-30). "Russian Money Suspected Behind Fracking Protests". New York Times. Retrieved 2014-12-04.
- Documentary: Gasland (2010). 104 minutes.
- "Gasland". 2010. Retrieved 2012-05-14.
- "Gasland Debunked" (PDF). Energy in Depth. Retrieved 2012-05-14.
- "Affirming Gasland" (PDF). July 2010. Retrieved 2010-12-21.
- COGCC Gasland Correction Document Colorado Department of Natural Resources 29 October 2010
- Gilbert, Daniel (7 October 2012). "Matt Damon Fracking Film Lights Up Petroleum Lobby". The Wall Street Journal ((subscription required)). Retrieved 26 December 2012.
- Gerhardt, Tina (31 December 2012). "Matt Damon Exposes Fracking in Promised Land". The Progressive. Retrieved 4 January 2013.
- Kickstarter, FrackNation by Ann and Phelim Media LLC, 6 April 2012
- The Hollywood Reporter, Mark Cuban's AXS TV Picks Up Pro-Fracking Documentary 'FrackNation', 17 December 2012
- "The Ethics of Fracking". Green Planet Films.
- "'Fractured Land' Doc Coming to VIFF". The Tyee. 2015-09-09. Retrieved 2015-10-20.
- Deller, Steven; Schreiber, Andrew (2012). "Mining and Community Economic Growth" (PDF). The Review of Regional Studies 42: 121–141. Retrieved 3 March 2013.
- Soraghan, Mike (12 March 2012). "Quiet foundation funds the 'anti-fracking' fight". E&E News. Retrieved 27 March 2013.
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.
- Urbina, Ian (3 March 2011). "Pressure Limits Efforts to Police Drilling for Gas". The New York Times. Retrieved 23 February 2012.
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
- "The Debate Over the Hydrofracking Study's Scope". The New York Times. 3 March 2011. Retrieved 1 May 2012.
While environmentalists have aggressively lobbied the agency to broaden the scope of the study, industry has lobbied the agency to narrow this focus
- "Natural Gas Documents". The New York Times. 27 February 2011. Retrieved 5 May 2012.
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.
- Finkel ML, Hays J (October 2013). "The implications of unconventional drilling for natural gas: a global public health concern". Public Health (Review) 127 (10): 889–93. doi:10.1016/j.puhe.2013.07.005. PMID 24119661.
- Public Health England. 25 June 2014 PHE-CRCE-009: Review of the potential public health impacts of exposures to chemical and radioactive pollutants as a result of shale gas extraction ISBN 978-0-85951-752-2
- Drajem, Mark (11 January 2012). "Fracking Political Support Unshaken by Doctors' Call for Ban". Bloomberg. Retrieved 19 January 2012.
- Alex Wayne (4 January 2012). "Health Effects of Fracking Need Study, Says CDC Scientist". Bloomberg Businessweek. Retrieved 29 February 2012.
- Centner, Terence J. (September 2013). "Oversight of shale gas production in the United States and the disclosure of toxic substances". Resources Policy 38 (3): 233–240. doi:10.1016/j.resourpol.2013.03.001. Retrieved 29 September 2014.
- Colborn, Theo; et al. (20 September 2011). "Natural Gas Operations from a Public Health Perspective" (PDF). Human and Ecological Risk Assessment 17 (5): 1039–1056. doi:10.1080/10807039.2011.605662.
- A. Kibble, T. Cabianca, Z. Daraktchieva, T. Gooding, J. Smithard, G. Kowalczyk, N. P. McColl, M. Singh, L. Mitchem, P. Lamb, S. Vardoulakis and R. Kamanyire (January 2014). Review of the Potential Public Health Impacts of Exposures to Chemical and Radioactive Pollutants as a Result of the Shale Gas Extraction Process (PDF) (Report). Public Health England. PHE-CRCE-009.
- Broomfield, Mark (2012-08-10). Support to the identification of potential risks for the environment and human health arising from hydrocarbons operations involving hydraulic fracturing in Europe (PDF) (Report). European Commission. pp. vi–xvi. ED57281. Retrieved 2014-09-29.
- "EU Commission minimum principles for the exploration and production of hydrocarbons (such as shale gas) using high-volume hydraulic fracturing". EUR LEX. Retrieved Nov 2014.
- "Energy and environment". EUR LEX.
- Lauver LS (August 2012). "Environmental health advocacy: an overview of natural gas drilling in northeast Pennsylvania and implications for pediatric nursing". J Pediatr Nurs 27 (4): 383–9. doi:10.1016/j.pedn.2011.07.012. PMID 22703686.
- "Air Quality" (PDF). DECC.
- Abdalla, Charles W.; Drohan, Joy R. (2010). Water Withdrawals for Development of Marcellus Shale Gas in Pennsylvania. Introduction to Pennsylvania’s Water Resources (PDF) (Report). The Pennsylvania State University. Retrieved 16 September 2012.
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)
- Faucon, Benoît (17 September 2012). "Shale-Gas Boom Hits Eastern Europe". WSJ.com. Retrieved 17 September 2012.
- New Research of Surface Spills in Fracking Industry. (2013). Professional Safety, 58(9), 18.
- Logan, Jeffrey (2012). Natural Gas and the Transformation of the U.S. Energy Sector: Electricity (PDF) (Report). Joint Institute for Strategic Energy Analysis. Retrieved 27 March 2013.
- Köster, Vera. "What is Shale Gas? How Does Fracking Work?". www.chemistryviews.org. Retrieved 4 December 2014.
- "Habitat Loss and Modification Due to Gas Development in the Fayetteville Shale". Springer. 2015-01-08. Retrieved 2015-12-23.
- Frederick J. Herrmann, Federal Railroad Administration, letter to American Petroleum Institute, 17 July 2013, p.4.
- Zoback, Mark; Kitasei, Saya; Copithorne, Brad (July 2010). Addressing the Environmental Risks from Shale Gas Development (PDF) (Report). Worldwatch Institute. p. 9. Retrieved 2012-05-24.
- Begley, Sharon; McAllister, Edward (12 July 2013). "News in Science: Earthquakes may trigger fracking tremors". ABC Science (Reuters). Retrieved 17 December 2013.
- "Fracking tests near Blackpool 'likely cause' of tremors". BBC News. 2 November 2011. Retrieved 22 February 2012.
- Injection-Induced Earthquakes, Science 341, W. L. Ellsworth, 2013. Retrieved 31 December 2014.
- Managing the seismic risk posed by wastewater disposal, Earth Magazine, 57:38–43 (2012), M. D. Zoback. Retrieved 31 December 2014.
- Nolon, John R.; Polidoro, Victoria (2012). "Hydrofracking: Disturbances Both Geological and Political: Who Decides?" (PDF). The Urban Lawyer 44 (3): 1–14. Retrieved 2012-12-21.
- Negro, Sorrell E. (February 2012). "Fracking Wars: Federal, State, and Local Conflicts over the Regulation of Natural Gas Activities" (PDF). Zoning and Planning Law Report (Thomson Reuters) 35 (2): 1–14. Retrieved 2014-05-01.
- "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"
- "Article L 110-1 du Code de l'Environnement"
- "Fracking ban upheld by French court". BBC. 11 October 2013. Retrieved 16 October 2013.
- Moore, Robbie. "Fracking, PR, and the Greening of Gas". The International. Retrieved 16 March 2013.
- Bakewell, Sally (13 December 2012). "U.K. Government Lifts Ban on Shale Gas Fracking". Bloomberg. Retrieved 26 March 2013.
- Hweshe, Francis (17 September 2012). "South Africa: International Groups Rally Against Fracking, TKAG Claims". West Cape News. Retrieved 11 February 2014.
- Nicola, Stefan; Andersen, Tino (26 February 2013). "Germany agrees on regulations to allow fracking for shale gas". Bloomberg. Retrieved 1 May 2014.
- Farah, Paolo Davide; Tremolada, Riccardo (2015). "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". Retrieved 16 November 2015.
- Healy, Dave (July 2012). Hydraulic Fracturing or 'Fracking': A Short Summary of Current Knowledge and Potential Environmental Impacts (PDF) (Report). Environmental Protection Agency. Retrieved 28 July 2013.
- Hass, Benjamin (14 August 2012). "Fracking Hazards Obscured in Failure to Disclose Wells". Bloomberg. Retrieved 27 March 2013.
- Soraghan, Mike (13 December 2013). "White House official backs FracFocus as preferred disclosure method". E&E News. Retrieved 27 March 2013.
- , Environmental Protection Agency
- "Gov. Cuomo Makes Sense on Fracking". The New York Times. 17 December 2014. Retrieved 18 December 2014.
- Nearing, Brian (18 December 2014). "Citing perils, state bans fracking". Times Union. Retrieved 25 January 2015.
- Brady, Jeff (18 December 2014). "Citing Health, Environment Concerns, New York Moves To Ban Fracking". NPR. Retrieved 25 January 2015.
|Wikimedia Commons has media related to Hydraulic fracturing.|
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- Natural Gas Extraction—Hydraulic Fracturing (EPA website)
- EPA's Draft Hydraulic Fracturing Study Plan
- The British Columbia (Canada) Oil and Gas Commission mandatory disclosure of hydraulic fracturing fluids
- Hydraulic Fracturing: Selected Legal Issues Congressional Research Service
- Fracking collected news and commentary at ProPublica
- Hydraulic Fracturing at Earthworks
- FracFocus Searchable database with chemical composition of fracking fluid of individual wells
- FracTracker.org: Maps, data, and articles from news, government, industry, and academic sources.
- 60 Minutes Report on Hydraulic Fracturing.
- Kiparsky, Michael; Hein, Jayni Foley (April 2013). "Regulation of Hydraulic Fracturing in California: A Wastewater and Water Quality Perspective" (PDF). University of California Center for Law, Energy, and the Environment. Retrieved 2014-05-01.
- Ridlington, Elizabeth; John Rumpler (3 October 2013). "Fracking by the numbers". Environment America.
- "DISH, TExas Exposure Investigation" (PDF). Texas DSHS. Retrieved 27 March 2013.
- de Pater, C.J.; Baisch, S. (2 November 2011). Geomechanical Study of Bowland Shale Seismicity (PDF) (Report). Cuadrilla Resources. Retrieved 22 February 2012.
- McKenzie, Lisa; Witter, Roxana; Newman, Lee; Adgate, John (2012). "Human health risk assessment of air emissions from development of unconventional natural gas resources". Science of the Total Environment 424: 79–87. doi:10.1016/j.scitotenv.2012.02.018. PMID 22444058.
- "The Hydraulic Fracturing Water Cycle". EPA. 16 March 2014. Retrieved 2014-10-10.
- Fernandez, John Michael; Gunter, Matthew. "Hydraulic Fracturing: Environmentally Friendly Practices" (PDF). Houston Advanced Research Center. Retrieved 2012-12-29.
- Colborn, Theo; Kwiatkowski, Carol; Schultz, Kim; Bachran, Mary (2011). "Natural gas operations from public health perspective". Human and Ecological Risk Assessment: an International Journal 17 (5): 1039–1056. doi:10.1080/10807039.2011.605662.
- Abdalla, Charles W.; Drohan, Joy R.; Blunk, Kristen Saacke; Edson, Jessie (2014). Marcellus Shale Wastewater Issues in Pennsylvania—Current and Emerging Treatment and Disposal Technologies (PDF) (Report). Penn State Extension. Retrieved 2014-10-11.
- Arthur, J. Daniel; Langhus, Bruce; Alleman, David (2008). An overview of modern shale gas development in the United States (PDF) (Report). ALL Consulting. p. 21. Retrieved 2012-05-07.
- Howe, J. Cullen; Del Percio, Stephen. The Legal and Regulatory Landscape of Hydraulic Fracturing (Report). LexisNexis. Retrieved 2014-05-07.
- Molofsky, L. J.; Connor, J. A.; Shahla, K. F.; Wylie, A. S.; Wagner, T. (5 December 2011). "Methane in Pennsylvania Water Wells Unrelated to Marcellus Shale Fracturing". Oil and Gas Journal (Pennwell Corporation) 109 (49): 54–67.
- IEA (2011). World Energy Outlook 2011. OECD. pp. 91; 164. ISBN 9789264124134.
- "How is hydraulic fracturing related to earthquakes and tremors?". USGS. Retrieved 4 November 2012.
- Moniz, Ernest J.; et al. (June 2011). The Future of Natural Gas: An Interdisciplinary MIT Study (PDF) (Report). Massachusetts Institute of Technology. Retrieved 1 June 2012.
- Biello, David (30 March 2010). "Natural gas cracked out of shale deposits may mean the U.S. has a stable supply for a century – but at what cost to the environment and human health?". Scientific American. Retrieved 23 March 2012.
- Schmidt, Charles (1 August 2011). "Blind Rush? Shale Gas Boom Proceeds Amid Human Health Questions". Environmental Health Perspectives 119 (8): a348–a353. doi:10.1289/ehp.119-a348. PMC 3237379. PMID 21807583.
- Allen, David T.; Torres, Vincent N.; Thomas, James; Sullivan, David W.; Harrison, Matthew; Hendler, Al; Herndon, Scott C.; Kolb, Charles E.; Fraser, Matthew P.; Hill, A. Daniel; Lamb, Brian K.; Miskimins, Jennifer; Sawyer, Robert F.; Seinfeld, John H. (16 September 2013). "Measurements of methane emissions at natural gas production sites in the United States" (PDF). Proceedings of the National Academy of Sciences. doi:10.1073/pnas.1304880110. Retrieved 2013-10-02.
- Kassotis, Christopher D.; Tillitt, Donald E.; Davis, J. Wade; Hormann, Annette M.; Nagel, Susan C. (March 2014). "Estrogen and Androgen Receptor Activities of Hydraulic Fracturing Chemicals and Surface and Ground Water in a Drilling-Dense Region". Endocrinology 155 (3). doi:10.1210/en.2013-1697. Retrieved 24 December 2013.
- Chalupka, S. (October 2012). "Occupational Silica Exposure in Hydraulic Fracturing". Workplace Health & Safety 60 (10): 460. doi:10.3928/21650799-20120926-70. Retrieved 10 October 2014.
- Smith, S. (1 August 2014). "Respirators Are Not Enough: New Study Examines Worker Exposure to Silica in Hydraulic Fracturing Operations". EHS Today. Retrieved 10 October 2014.
- "Waste water (flowback)from hydraulic fracturing" (PDF). Ohio Department of Natural Resources. Retrieved 29 June 2013.
- Spath, Ph.D., P.E., David P. (November 1997). Policy Memo 97-005 Policy Guidance for Direct Domestic Use of Extremely Impaired Sources (PDF) (Report). State of California Department of Health Services. Retrieved 7 October 2014.
- Weinhold, Bob (19 September 2012). "Unknown Quantity: Regulating Radionuclides in Tap Water". Environmental Health Perspectives. NIEHS, NIH. Retrieved 11 February 2012.
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...
- Rachel Maddow, Terrence Henry (7 August 2012). Rachel Maddow Show: Fracking waste messes with Texas (video). MSNBC. Event occurs at 9:24 - 10:35.
- Cothren, Jackson. Modeling the Effects of Non-Riparian Surface Water Diversions on Flow Conditions in the Little Red Watershed (PDF) (Report). U. S. Geological Survey, Arkansas Water Science Center Arkansas Water Resources Center, American Water Resources Association, Arkansas State Section Fayetteville Shale Symposium 2012. p. 12. Retrieved 16 September 2012.
...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
- Janco, David F. (1 February 2007). 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. (PDF) (Report). Scranton Times-Tribune. Retrieved 27 December 2013.
- Janco, David F. (3 January 2008). 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 (PDF) (Report). Scranton Times-Tribune. Retrieved 27 December 2013.
- Lustgarten, Abrahm (21 June 2012). "Are Fracking Wastewater Wells Poisoning the Ground beneath Our Feet? Leaking injection wells may pose a risk--and the science has not kept pace with the growing glut of wastewater". Scientific American. Retrieved 2014-10-11.
- Rabinowitz, Peter M.; Rabinowitz, Ilya B.; Slizovskiy, Vanessa; Lamers, Sally J.; Trufan, Theodore R.; Holford, James D.; Dziura, Peter N.; Peduzzi, Michael J.; Kane, John S.; Reif, John; Weiss, Theresa R.; Stowe1, Meredith H. (2014). "Proximity to Natural Gas Wells and Reported Health Status: Results of a Household Survey in Washington County, Pennsylvania". Environmental Health Perspectives (US National Institute of Environmental Health Sciences). doi:10.1289/ehp.1307732. Retrieved 2014-10-07.
- Arthur, J. Daniel; Uretsky, Mike; Wilson, Preston (5–6 May 2010). Water Resources and Use for Hydraulic Fracturing in the Marcellus Shale Region (PDF). Meeting of the American Institute of Professional Geologists. Pittsburgh: ALL Consulting. p. 3. Retrieved 2012-05-09.
- Colborn, Theo; Kwiatkowski, Carol; Schultz, Kim; Bachran, Mary (2011). "Natural Gas Operations from a Public Health Perspective" (PDF). Human and Ecological Risk Assessment: an International Journal (Taylor & Francis) 17 (5): 1039–1056. doi:10.1080/10807039.2011.605662.
- Osborn, Stephen G.; Vengosh, Avner; Warner, Nathaniel R.; Jackson, Robert B. (2011-05-17). "Methane contamination of drinking water accompanying gas-well drilling and hydraulic fracturing" (PDF). Proceedings of the National Academy of Sciences of the United States of America 108 (20): 8172–8176. doi:10.1073/pnas.1100682108. Retrieved 2011-10-14.
- Nicholas St. Fleur (19 December 2014). "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". The Atlantic. Retrieved 21 December 2014.
- Gallegos, T.J. and B.A. Varela (2015). 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.