Hydraulic fracturing

“Fracking” redirects here. For other uses, see Frack(disambiguation).

Hydraulic fracturing (also hydrofracturing, hy-drofracking, fracking, or fraccing) is a well-stimulationtechnique in which rock is fractured by a hydraulicallypressurized liquid. Some hydraulic fractures formnaturally—certain veins or dikes are examples.[1] A high-pressure fluid (usually chemicals and sand suspendedin water) is injected into a wellbore to create cracksin the deep-rock formations through which natural gas,petroleum, and brine will flow more freely. When the hy-draulic pressure is removed from the well, small grainsof hydraulic fracturing proppants (either sand or alu-minium oxide) hold the fractures open once the deep rockachieves geologic equilibrium.The hydraulic fracturing technique is commonly appliedto wells for shale gas, tight gas, tight oil, and coal seamgas.[2] Such well stimulation is commonly used to increaseflow rates.Hydraulic fracturing began as an experiment in 1947, andthe first commercially successful application followed in1949. As of 2012, 2.5 million hydraulic fracturing opera-tions had been performed worldwide on oil and gas wells;over one million of those within the U.S.[3][4]

Hydraulic fracturing is highly controversial, propo-nents advocating economic benefits of readily accessi-ble hydrocarbons,[5][6] and opponents concerned for theenvironmental impact of hydraulic fracturing includingcontamination of ground water, depletion of fresh wa-ter, degradation of the air quality, the triggering ofearthquakes, noise pollution, surface pollution, and theconsequential risks to health and the environment.[7]

Increases in seismic activity following hydraulic frac-turing along dormant or previously unknown faults aresometimes caused by the deep-injection disposal of hy-draulic fracturing flowback (a byproduct of hydrauli-cally fractured wells),[8] and produced formation brine (abyproduct of both fractured and nonfractured oil and gaswells).[9] For these reasons, hydraulic fracturing is un-der international scrutiny, restricted in some countries,and banned altogether in others.[10][11][12] Some of thosecountries, notably the U.K., have repealed bans on hy-draulic fracturing in favour of regulation. The EuropeanUnion is drafting regulations that would permit controlledapplication of hydraulic fracturing.[13]

1 Geology

Halliburton fracturing operation in the Bakken Formation, NorthDakota, United States

A fracturing operation in progress

Main article: Fracture (geology)

1.1 Mechanics

Fracturing in rocks at depth tends to be suppressed bythe pressure of the overlying rock stratas weight, and thecementation of the formation. This is particularly sig-nificant in “tensile” (Mode 1) fractures which requirethe walls of the fracture to move against this pressure.Fracturing occurs when effective stress is overcome bythe pressure of fluids within the rock. The minimumprincipal stress becomes tensile and exceeds the tensile

1

2 2 HISTORY

strength of the material.[14][15] Fractures formed in thisway are generally oriented in a plane perpendicular to theminimum principal stress, and for this reason, hydraulicfractures in well bores can be used to determine the orien-tation of stresses.[16] In natural examples, such as dikes orvein-filled fractures, the orientations can be used to inferpast states of stress.[17]

1.2 Veins

Most mineral vein systems are a result of repeated natu-ral fracturing during periods of relatively high pore fluidpressure. This is particularly evident in “crack-seal”veins, where the vein material is part of a series of dis-crete fracturing events, and extra vein material is de-posited on each occasion.[18] One example of long-termrepeated natural fracturing is in the effects of seismic ac-tivity. Stress levels rise and fall episodically, and earth-quakes can cause large volumes of connate water to beexpelled from fluid-filled fractures. This process is re-ferred to as “seismic pumping”.[19]

1.3 Dikes

Minor intrusions in the upper part of the crust, such asdikes, propagate in the form of fluid-filled cracks. Insuch cases, the fluid is magma. In sedimentary rocks witha significant water content, fluid at fracture tip will besteam.[20]

2 History

2.1 Precursors

Fracturing as a method to stimulate shallow, hard rockoil wells dates back to the 1860s. Dynamite or nitro-glycerin detonations were used to increase oil and naturalgas production from petroleum bearing formations. OnApril 25, 1865, Civil War veteran Col. Edward A. L.Roberts received a patent for an "exploding torpedo".[21]

It was employed in Pennsylvania, New York, Kentucky,and West Virginia using liquid and also, later, solidifiednitroglycerin. Later still the same method was appliedto 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 completelyresulting in further productivity increase.[22]

2.2 Oil and gas wells

The relationship between well performance and treatmentpressures was studied by Floyd Farris of Stanolind Oiland Gas Corporation. This study was the basis of thefirst hydraulic fracturing experiment, conducted in 1947

at the Hugoton gas field in Grant County of southwesternKansas by Stanolind.[2][23] For the well treatment, 1,000US gallons (3,800 l; 830 imp gal) of gelled gasoline (es-sentially napalm) and sand from the Arkansas River wasinjected into the gas-producing limestone formation at2,400 feet (730 m). The experiment was not very suc-cessful as deliverability of the well did not change appre-ciably. The process was further described by J.B. Clarkof Stanolind in his paper published in 1948. A patent onthis process was issued in 1949 and exclusive license wasgranted to the Halliburton Oil Well Cementing Company.On March 17, 1949, Halliburton performed the first twocommercial hydraulic fracturing treatments in StephensCounty, Oklahoma, and Archer County, Texas.[23] Sincethen, hydraulic fracturing has been used to stimulate ap-proximately one million oil and gas wells[24] in variousgeologic regimes with good success.In contrast with large-scale hydraulic fracturing used inlow-permeability formations, small hydraulic fracturingtreatments are commonly used in high-permeability for-mations to remedy “skin damage”, a low-permeabilityzone that sometimes forms at the rock-borehole interface.In such cases the fracturing may extend only a few feetfrom the borehole.[25]

In the Soviet Union, the first hydraulic proppantfracturing was carried out in 1952. Other coun-tries in Europe and Northern Africa subsequently em-ployed hydraulic fracturing techniques including Norway,Poland, Czechoslovakia, Yugoslavia, Hungary, Austria,France, Italy, Bulgaria, Romania, Turkey, Tunisia, andAlgeria.[26]

2.3 Massive fracturing

Massive hydraulic fracturing (also known as high-volumehydraulic fracturing) is a technique first applied by PanAmerican Petroleum in Stephens County, Oklahoma,USA in 1968. The definition of massive hydraulic frac-turing varies somewhat, but is generally reference totreatments injecting greater than about 150 short tons, orapproximately 300,000 pounds (136 metric tonnes), ofproppant.[27]

American geologists became increasingly aware thatthere were huge volumes of gas-saturated sandstones withpermeability too low (generally less than 0.1 millidarcy)to recover the gas economically.[27] Starting in 1973,massive hydraulic fracturing was used in thousands ofgas wells in the San Juan Basin, Denver Basin,[28] thePiceance Basin,[29] and the Green River Basin, and inother hard rock formations of the western US. Other tightsandstone wells in the US made economically viable bymassive hydraulic fracturing were in the Clinton-MedinaSandstone, and Cotton Valley Sandstone.[27]

Massive hydraulic fracturing quickly spread in the late1970s to western Canada, Rotliegend and Carboniferousgas-bearing sandstones in Germany, Netherlands (on-

2.4 Shales 3

Well Head where fluids are injected into the ground

Well head after all the hydraulic fracturing equipment has beentaken off location

shore and offshore gas fields), and the United Kingdomin the North Sea.[26]

Horizontal oil or gas wells were unusual until the late1980s. Then, operators in Texas began completing thou-sands of oil wells by drilling horizontally in the AustinChalk, and giving massive slickwater hydraulic fractur-ing treatments to the wellbores. Horizontal wells provedmuch more effective than vertical wells in producing oilfrom tight chalk;[30] shale runs horizontally, so a horizon-tal well reaches much more of the resource.[31] The firsthorizontal well was drilled in the Barnett Shale in 1991[31]

and slickwater fluids were introduced in 1996.[31]

2.4 Shales

Due to shale’s high porosity and low permeability, tech-nological research, development and demonstration werenecessary before hydraulic fracturing accepted for com-mercial application to shale gas deposits. In 1976, theUnited States government started the Eastern Gas ShalesProject, a set of dozens of public-private hydraulic frac-turing demonstration projects.[32] During the same pe-riod, the Gas Research Institute, a gas industry researchconsortium, received approval for research and fundingfrom the Federal Energy Regulatory Commission.[33]

In 1997, taking the slickwater fracturing technique usedin East Texas by Union Pacific Resources (now part ofAnadarko Petroleum Corporation), Mitchell Energy (nowpart of Devon Energy), learned how to use the tech-nique in the Barnett Shale of north Texas. This madeshale gas extraction widely economical.[34][35][36] GeorgeP. Mitchell has been called the “father of fracking” be-cause of his role in applying it in shales.[37]

As of 2013, massive hydraulic fracturing is being ap-plied on a commercial scale to shales in the United States,Canada, and China. Several countries are planning to usehydraulic fracturing.[38][39][40]

3 Process

According to the United States Environmental ProtectionAgency (EPA) hydraulic fracturing is a process to stimu-late a natural gas, oil, or geothermal energy well to max-imize extraction. EPA defines the broader process as in-cluding the acquisition of source water, well construction,well stimulation, and waste disposal.[41]

3.1 Method

A hydraulic fracture is formed by pumping fracturingfluid into a wellbore at a rate sufficient to increase pres-sure at the target depth (determined by the location of thewell casing perforations), to exceed that of the fracturegradient (pressure gradient) of the rock.[42] The fracturegradient is defined as pressure increase per unit of depthrelative to density, and is usually measured in pounds persquare inch, per foot, or bars per metre. The rock cracks,and the fracture fluid permeates the rock extending thecrack further, and further, and so on. Fractures are lo-calized as pressure drops off with the rate of frictionalloss, which is relevant to the distance from the well. Op-erators typically try to maintain “fracture width”, or slowits decline following treatment, by introducing a proppantinto the injected fluid – a material such as grains of sand,ceramic, or other particulate, thus preventing the frac-tures from closing when injection is stopped and pres-sure removed. Consideration of proppant strength andprevention of proppant failure becomes more important

4 3 PROCESS

at greater depths where pressure and stresses on fracturesare higher. The propped fracture is permeable enough toallow the flow of gas, oil, salt water and hydraulic frac-turing fluids to the well.[42]

During the process, fracturing fluid leakoff (loss of frac-turing fluid from the fracture channel into the surround-ing permeable rock) occurs. If not controlled, it can ex-ceed 70% of the injected volume. This may result in for-mation matrix damage, adverse formation fluid interac-tion, and altered fracture geometry, thereby decreasingefficiency.[43]

The location of one or more fractures along the length ofthe borehole is strictly controlled by various methods thatcreate or seal holes in the side of the wellbore. Hydraulicfracturing is performed in cased wellbores, and the zonesto be fractured are accessed by perforating the casing atthose locations.[44]

Hydraulic-fracturing equipment used in oil and naturalgas fields usually consists of a slurry blender, one or morehigh-pressure, high-volume fracturing pumps (typicallypowerful triplex or quintuplex pumps) and a monitor-ing unit. Associated equipment includes fracturing tanks,one or more units for storage and handling of proppant,high-pressure treating iron, a chemical additive unit (usedto accurately monitor chemical addition), low-pressureflexible hoses, and many gauges and meters for flow rate,fluid density, and treating pressure.[45] Chemical addi-tives are typically 0.5% percent of the total fluid volume.Fracturing equipment operates over a range of pressuresand injection rates, and can reach up to 100 megapascals(15,000 psi) and 265 litres per second (9.4 cu ft/s) (100barrels per minute).[46]

3.2 Well types

A distinction can be made between conventional, low-volume hydraulic fracturing, used to stimulate high-permeability reservoirs for a single well, and unconven-tional, high-volume hydraulic fracturing, used in the com-pletion of tight gas and shale gas wells. Unconventionalwells are deeper and require higher pressures than con-ventional vertical wells.[47]

Horizontal drilling involves wellbores with a terminaldrillhole completed as a “lateral” that extends parallelwith the rock layer containing the substance to be ex-tracted. For example, laterals extend 1,500 to 5,000 feet(460 to 1,520 m) in the Barnett Shale basin in Texas, andup to 10,000 feet (3,000 m) in the Bakken formation inNorth Dakota. In contrast, a vertical well only accessesthe thickness of the rock layer, typically 50–300 feet (15–91 m). Horizontal drilling reduces surface disruptions asfewer wells are required to access the same volume ofrock. Drilling usually induces damage to the pore spaceat the wellbore wall, reducing permeability at and nearthe wellbore. This reduces flow into the borehole fromthe surrounding rock formation, and partially seals off the

borehole from the surrounding rock. Hydraulic fracturingcan be used to restore permeability,[48] but is not typicallyadministered in this way.

3.3 Fracturing fluids in the United States

Water tanks preparing for hydraulic fracturing

Main articles: Hydraulic fracturing proppants and Listof additives for hydraulic fracturing

The main purposes of fracturing fluid are to extend frac-tures, add lubrication, change gel strength, and to carryproppant into the formation. There are two methods oftransporting proppant in the fluid – high-rate and high-viscosity. High-viscosity fracturing tends to cause largedominant fractures, while high-rate (slickwater) fractur-ing causes small spread-out micro-fractures.Water-soluble gelling agents (such as guar gum) in-crease viscosity and efficiently deliver proppant into theformation.[49]

Process of mixing water with hydraulic fracturing fluids to beinjected into the ground

Fluid is typically a slurry of water, proppant, andchemical additives.[50] Additionally, gels, foams, andcompressed gases, including nitrogen, carbon dioxide and

3.3 Fracturing fluids in the United States 5

air can be injected. Typically, 90% of the fluid is wa-ter and 9.5% is sand with chemical additives accountingto about 0.5%.[42][51][52] However, fracturing fluids havebeen developed using liquefied petroleum gas (LPG) andpropane in which water is unnecessary.[53]

A proppant is a material that will keep an induced hy-draulic fracture open during or following a fracturingtreatment, and can be gel, foam, or slickwater-based.Fluid choices are tradeoffs between material propertiessuch as viscosity, where more viscous fluids can carrymore concentrated proppant, energy or pressure demandsto maintain a flux pump rate (flow velocity) that will con-duct the proppant appropriately, pH, various rheologicalfactors, and others. Types of proppant include silica sand,resin-coated sand, and man-made ceramics. These varydepending on the type of permeability or grain strengthneeded. The most commonly used proppant is silica sand,though proppants of uniform size and shape, such as a ce-ramic proppant, is believed to be more effective.[54]

The fracturing fluid varies depending on fracturing type,conditions of specific wells being fractured, and watercharacteristics. A typical fracture treatment uses between3 and 12 additive chemicals.[42] Although there may beunconventional fracturing fluids, typical chemical addi-tives can include one or more of the following:

• Acids—hydrochloric acid or acetic acid is used inthe pre-fracturing stage for cleaning the perforationsand initiating fissure in the near-wellbore rock.[52]

• Sodium chloride (salt)—delays breakdown of gelpolymer chains.[52]

• Polyacrylamide and other friction reducers decreaseturbulence in fluid flow and pipe friction, thus al-lowing the pumps to pump at a higher rate withouthaving greater pressure on the surface.[52]

• Ethylene glycol—prevents formation of scale de-posits in the pipe.[52]

• Borate salts—used for maintaining fluid viscosityduring the temperature increase.[52]

• Sodium and potassium carbonates—used for main-taining effectiveness of crosslinkers.[52]

• Glutaraldehyde—used as disinfectant of the water(bacteria elimination).[52]

• Guar gum and other water-soluble gelling agents—increases viscosity of the fracturing fluid to deliverproppant into the formation more efficiently.[49][52]

• Citric acid—used for corrosion prevention.

• Isopropanol—increases the viscosity of the fracturefluid.[52]

The most common chemical used for hydraulic fracturingin the United States in 2005–2009 was methanol, whilesome other most widely used chemicals were isopropylalcohol, 2-butoxyethanol, and ethylene glycol.[55]

Typical fluid types are:

• Conventional linear gels. These gels are cellulosederivative (carboxymethyl cellulose, hydroxyethylcellulose, carboxymethyl hydroxyethyl cellulose,hydroxypropyl cellulose, methyl hydroxyl ethyl cel-lulose), guar or its derivatives (hydroxypropyl guar,carboxymethyl hydroxypropyl guar), mixed withother chemicals.

• Borate-crosslinked fluids. These are guar-basedfluids cross-linked with boron ions (from aqueousborax/boric acid solution). These gels have higherviscosity at pH 9 onwards and are used to carry prop-pant. After the fracturing job, the pH is reduced to3–4 so that the cross-links are broken, and the gel isless viscous and can be pumped out.

• Organometallic-crosslinked fluids zirconium,chromium, antimony, titanium salts are known tocrosslink the guar-based gels. The crosslinkingmechanism is not reversible, so once the proppantis pumped down along with cross-linked gel, thefracturing part is done. The gels are broken downwith appropriate breakers.[49]

• Aluminium phosphate-ester oil gels. Aluminiumphosphate and ester oils are slurried to form cross-linked gel. These are one of the first known gellingsystems.

For slickwater it is common to include sweeps or a tempo-rary reduction in the proppant concentration to ensure thewell is not overwhelmed with proppant causing a screen-off.[56] As the fracturing process proceeds, viscosity re-ducing agents such as oxidizers and enzyme breakers aresometimes then added to the fracturing fluid to deactivatethe gelling agents and encourage flowback.[49] The oxi-dizer reacts with the gel to break it down, reducing thefluid’s viscosity, and ensuring that no proppant is pulledfrom the formation. An enzyme acts as a catalyst forbreaking down the gel. Sometimes pH modifiers are usedto break down the crosslink at the end of a hydraulic frac-turing job since many require a pH buffer system to stayviscous.[56] At the end of the job, the well is commonlyflushed with water (sometimes blended with a friction re-ducing chemical) under pressure. Injected fluid is re-covered to some degree and managed by several meth-ods such as underground injection control, treatment anddischarge, recycling, or temporary storage in pits or con-tainers. New technology is continually being developedto better handle waste water and improve re-usability.[42]

6 3 PROCESS

3.4 Fracture monitoring

Measurements of the pressure and rate during the growthof a hydraulic fracture, with knowledge of fluid proper-ties and proppant being injected into the well, providesthe most common and simplest method of monitoring ahydraulic fracture treatment. This data along with knowl-edge of the underground geology can be used to modelinformation such as length, width and conductivity of apropped fracture.[42]

Injection of radioactive tracers along with the frac-turing fluid is sometimes used to determine the in-jection profile and location of created fractures.[57]

Radiotracers are selected to have the readily detectableradiation, appropriate chemical properties, and a half lifeand toxicity level that will minimize initial and resid-ual contamination.[58] Radioactive isotopes chemicallybonded to glass (sand) and/or resin beads may also beinjected to track fractures.[59] For example, plastic pel-lets coated with 10 GBq of Ag-110mm may be added tothe proppant, or sand may be labelled with Ir-192, so thatthe proppant’s progress can be monitored.[58] Radiotrac-ers such as Tc-99m and I-131 are also used to measureflow rates.[58] The Nuclear Regulatory Commission pub-lishes guidelines which list a wide range of radioactivematerials in solid, liquid and gaseous forms that may beused as tracers and limit the amount that may be used perinjection and per well of each radionuclide.[59]

3.4.1 Microseismic monitoring

For more advanced applications, microseismic monitor-ing is sometimes used to estimate the size and orientationof induced fractures. Microseismic activity is measuredby placing an array of geophones in a nearby wellbore. Bymapping the location of any small seismic events associ-ated with the growing fracture, the approximate geometryof the fracture is inferred. Tiltmeter arrays deployed onthe surface or down a well provide another technology formonitoring strain[60]

Microseismic mapping is very similar geophysically toseismology. In earthquake seismology, seismometersscattered on or near the surface of the earth record S-waves and P-waves that are released during an earthquakeevent. This allows for motion along the fault plane tobe estimated and its location in the earth’s subsurfacemapped. Hydraulic fracturing, an increase in formationstress proportional to the net fracturing pressure, as wellas an increase in pore pressure due to leakoff.[61] Tensilestresses are generated ahead of the fractures tip generat-ing large amounts of shear stress. The increase in porewater pressure and formation stress combine and affectweaknesses (natural fractures, joints, and bedding planes)near the hydraulic fracture.[62]

Different methods have different location errors and ad-vantages. Accuracy of microseismic event mapping is de-

pendent on the signal-to-noise ratio and the distributionof sensors. Accuracy of events located by seismic inver-sion is improved by sensors placed in multiple azimuthsfrom the monitored borehole. In a downhole array loca-tion, accuracy of events is improved by being close to themonitored borehole (high signal-to-noise ratio).Monitoring of microseismic events induced by reservoirstimulation has become a key aspect in evaluation of hy-draulic fractures, and their optimization. The main goalof hydraulic fracture monitoring is to completely char-acterize the induced fracture structure, and distributionof conductivity within a formation. Geomechanical anal-ysis, such as understanding a formations material prop-erties, in-situ conditions, and geometries, helps monitor-ing by providing a better definition of the environment inwhich the fracture network propagates.[63] The next taskis to know the location of proppant within the fractureand the distribution of fracture conductivity. This can bemonitored using multiple types of techniques to finallydevelop a reservoir model than accurately predicts wellperformance.

3.5 Horizontal completions

Since the early 2000s, advances in drilling andcompletion technology have made horizontal well-bores much more economical. Horizontal wellboresallow far greater exposure to a formation than conven-tional vertical wellbores. This is particularly useful inshale formations which do not have sufficient permeabil-ity to produce economically with a vertical well. Suchwells, when drilled onshore, are now usually hydraulicallyfractured in a number of stages, especially in NorthAmerica. The type of wellbore completion is used todetermine how many times a formation is fractured, andat what locations along the horizontal section.[64]

In North America, shale reservoirs such as the Bakken,Barnett, Montney, Haynesville, Marcellus, and most re-cently the Eagle Ford, Niobrara and Utica shales aredrilled horizontally through the producing interval(s),completed and fractured. The method by which the frac-tures are placed along the wellbore is most commonlyachieved by one of two methods, known as “plug andperf” and “sliding sleeve”.[65]

The wellbore for a plug and perf job is generally com-posed of standard steel casing, cemented or uncemented,set in the drilled hole. Once the drilling rig has been re-moved, a wireline truck is used to perforate near the bot-tom of the well, and then fracturing fluid is pumped. Thenthe wireline truck sets a plug in the well to temporarilyseal off that section so the next section of the wellborecan be treated. Another stage is pumped, and the processis repeated along the horizontal length of the wellbore.[66]

The wellbore for the sliding sleeve technique is differentin that the sliding sleeves are included at set spacings inthe steel casing at the time it is set in place. The slid-

7

ing sleeves are usually all closed at this time. When thewell is due to be fractured, the bottom sliding sleeve isopened using one of several activation techniques and thefirst stage gets pumped. Once finished, the next sleeve isopened, concurrently isolating the previous stage, and theprocess repeats. For the sliding sleeve method, wirelineis usually not required.

Sleeves

These completion techniques may allow for more than 30stages to be pumped into the horizontal section of a singlewell if required, which is far more than would typicallybe pumped into a vertical well that had far fewer feet ofproducing zone exposed.[67]

4 Uses

Hydraulic fracturing is used to increase the rate at whichfluids, such as petroleum, water, or natural gas can be re-covered from subterranean natural reservoirs. Reservoirsare typically porous sandstones, limestones or dolomiterocks, but also include “unconventional reservoirs” suchas shale rock or coal beds. Hydraulic fracturing enablesthe extraction of natural gas and oil from rock forma-tions deep below the earth’s surface (generally 2,000–6,000 m (5,000–20,000 ft)), which is greatly below typ-ical groundwater reservoir levels. At such depth, theremay be insufficient permeability or reservoir pressure toallow natural gas and oil to flow from the rock into thewellbore at high economic return. Thus, creating con-ductive fractures in the rock is instrumental in extractionfrom naturally impermeable shale reservoirs. Permeabil-ity is measured in the microdarcy to nanodarcy range.[68]

Fractures are a conductive path connecting a larger vol-ume of reservoir to the well. So-called “super fracking,”creates cracks deeper in the rock formation to releasemore oil and gas, and increases efficiency.[69] The yieldfor typical shale bores generally falls off after the firstyear or two, but the peak producing life of a well can beextended to several decades.[70]

While the main industrial use of hydraulic fracturing is instimulating production from oil and gas wells,[71][72][73]

hydraulic fracturing is also applied:

• To stimulate groundwater wells[74]

• To precondition or induce rock cave-ins mining[75]

• As a means of enhancing waste remediation, usuallyhydrocarbon waste or spills[76]

• To dispose waste by injection deep into rock[77]

• To measure stress in the Earth[78]

• For electricity generation in enhanced geothermalsystems[79]

• To increase injection rates for geologic sequestrationof CO2[80]

Since the late 1970s, hydraulic fracturing has been used,in some cases, to increase the yield of drinking water fromwells in a number of countries, including the US, Aus-tralia, and South Africa.[81][82][83]

5 Economic effects

See also: Shale gas and Tight oil

Hydraulic fracturing has been seen as one of the keymethods of extracting unconventional oil and gas re-sources. According to the International Energy Agency,the remaining technically recoverable resources of shalegas are estimated to amount to 208 trillion cubic me-tres (208,000 km3), tight gas to 76 trillion cubic metres(76,000 km3), and coalbed methane to 47 trillion cubicmetres (47,000 km3). As a rule, formations of these re-sources have lower permeability than conventional gasformations. Therefore depending on the geological char-acteristics of the formation, specific technologies (suchas hydraulic fracturing) are required. Although there arealso other methods to extract these resources, such as con-ventional drilling or horizontal drilling, hydraulic fractur-ing is one of the key methods making their extraction eco-nomically viable. The multi-stage fracturing techniquehas facilitated the development of shale gas and light tightoil production in the United States and is believed to doso in the other countries with unconventional hydrocar-bon resources.[5]

The National Petroleum Council estimates that hydraulicfracturing will eventually account for nearly 70% of nat-ural gas development in North America.[84] Hydraulicfracturing and horizontal drilling apply the latest tech-nologies and make it commercially viable to recover shalegas and oil. In the United States, 45% of domestic naturalgas production and 17% of oil production would be lostwithin 5 years without usage of hydraulic fracturing.[85]

8 6 ENVIRONMENTAL IMPACT

U.S.-based refineries have gained a competitive edge withtheir access to relatively inexpensive shale oil and Cana-dian crude. The U.S. is exporting more refined petroleumproducts, and also more liquified petroleum gas (LP gas).LP gas is produced from hydrocarbons called natural gasliquids, released by the hydraulic fracturing of petrolif-erous shale, in a variety of shale gas that’s relatively easyto export. Propane, for example, costs around $620 aton in the U.S. compared with more than $1,000 a ton inChina, as of early 2014. Japan, for instance, is importingextra LP gas to fuel power plants, replacing idled nuclearplants. Trafigura Beheer BV, the third-largest indepen-dent trader of crude oil and refined products, said at thestart of 2014 that “growth in U.S. shale production hasturned the distillates market on its head.”[86]

Some studies call into question the claim that what hasbeen called the “shale gas revolution” has a significantmacro-economic impact. A study released in the begin-ning of 2014 by the IDDRI concluded the contrary. Itstates that, on the long-term as well as on the short-run,the “shale gas revolution” due to hydraulic fracturing inthe United States has had very little impact on economicgrowth and competitiveness.[87] The same report con-cludes that in Europe, using hydraulic fracturing wouldhave very little advantage in terms of competitiveness andenergy security. Indeed, for the period 2030-2035, shalegas is estimated to cover 3 to 10% of EU projected energydemand, which is not enough to have a significant impacton energetic independence and competitiveness .[87]

Hydrofracked shale oil and gas has the potential to alterthe geography of energy production in the US.[88][89]Inthe short run, in counties with hydrofracturing employ-ment in the oil and gas sector more than doubled in thelast 10 years, with spill-overs in local transport-, construc-tion but also manufacturing sectors.[88] The manufactur-ing sector benefits from lower energy prices, giving theUS manufacturing sector a competitive edge. On aver-age, natural gas prices have decreased by more than 30%in counties above shale deposits compared to the rest ofthe US. Some research has highlighted the negative ef-fects on house prices for properties in the direct vicinityof fracturing wells.[90] Local house prices in Pennsylva-nia decrease if the property is close to a hydrofrackinggas well and is not connected to city water, suggestingthat the concerns of ground water pollution are priced bymarkets.

6 Environmental impact

Main article: Environmental impact of hydraulic frac-turingSee also: Environmental impact of hydraulic fracturingin the United States and Exemptions for hydraulicfracturing under United States federal law

The environmental impacts of hydraulic fracturing are airemissions and climate change, high water consumption,water contamination, land use, risk of earthquakes, noisepollution, and health effects on humans. Air emissionsare primarily methane that escapes from wells, along withindustrial emissions from equipment used in the extrac-tion process.[91] Modern UK and EU regulation requireszero emissions of methane, a potent greenhouse gas.[92]

Escape of a methane is a bigger problem in older wellsthan in ones built under more recent EU legislation.[91]

Hydraulic fracturing uses between 1.2 and 3.5 millionUS 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 arerefractured.[49][93] An average well requires 3 to 8 mil-lion US gallons (11,000 to 30,000 m3) of water over itslifetime.[42] According to the Oxford Institute for En-ergy Studies, greater volumes of fracturing fluids are re-quired in Europe, where the shale depths average 1.5times greater than in the U.S.[94] Surface water may becontaminated through spillage and improperly built andmaintained waste pits,[95] and ground water can be con-taminated if the fluid is able to escape the formation be-ing fractured (through, for example, abandoned wells)or by produced water (the returning fluids, which alsocontain dissolved constituents such as minerals and brinewaters).[96] Produced water is managed by undergroundinjection, municipal and commercial wastewater treat-ment and discharge, self‐contained systems at well sitesor fields, and recycling to fracture future wells.[97] Typi-cally less than half of the produced water used to fracturethe formation is recovered.[98]

Hydraulic fracturing causes induced seismicity or earth-quakes. The magnitude of these events is usually toosmall to be detected at the surface, although tremorsattributed to fluid injection into disposal wells havebeen large enough to be felt by people on numerousoccasions.[8][99][100][101]

About 3.6 hectares (8.9 acres) of land is needed per eachdrill pad for surface installations. These sites need to beremediated after wells are exhausted.[91] Each well pad(in average 10 wells per pad) needs during preparatoryand hydraulic fracturing process about 800 to 2,500 daysof noisy activity, which affect both residents and localwildlife. In addition, noise is created by continuous trucktraffic (sand, etc.) needed in hydraulic fracturing.[91] Re-search is underway to determine if human health has beenaffected by air and water pollution, and rigorous follow-ing of safety procedures and regulation is required toavoid harm and to manage the risk of accidents that couldcause harm.[96]

In July 2013, the US Federal Railroad Administrationlisted oil contamination by hydraulic fracturing chemicalsas “a possible cause” of corrosion in oil tank cars.[102]

8.1 Politics and public policy 9

7 Regulations

See also: Hydraulic fracturing by country and Regulationof hydraulic fracturing

Countries using or considering to use hydraulic fracturinghave implemented different regulations, including devel-oping federal and regional legislation, and local zoninglimitations.[103][104] In 2011, after public pressure Francebecame the first nation to ban hydraulic fracturing, basedon the precautionary principle as well as the princi-pal of preventive and corrective action of environmentalhazards.[11][12][105][106] The ban was upheld by an Octo-ber 2013 ruling of the Constitutional Council.[107] Someother countries have placed a temporary moratorium onthe practice.[108] Countries like the United Kingdom andSouth Africa have lifted their bans, choosing to focus onregulation instead of outright prohibition.[109][110] Ger-many has announced draft regulations that would allowusing hydraulic fracturing for the exploitation of shale gasdeposits with the exception of wetland areas.[111]

The European Union has adopted a recommendationfor minimum principles for using high-volume hydraulicfracturing.[13] Its regulatory regime requires full disclo-sure of all additives.[112] In the United States, the GroundWater Protection Council launched FracFocus.org, anonline voluntary disclosure database for hydraulic frac-turing fluids funded by oil and gas trade groups and theU.S. Department of Energy.[113][114] Hydraulic fracturingis excluded from the Safe Drinking Water Act's under-ground injection control’s regulation, except when dieselfuel is used. The EPA assures surveillance of the issuanceof drilling permits when diesel fuel is employed.[115]

On December 17, 2014, New York became the first statein the United States to issue a full and complete ban onany hydraulic fracturing.[116][117]

8 Public debate

Poster against hydraulic fracturing in Vitoria-Gasteiz, Spain, Oc-tober 2012

8.1 Politics and public policy

An anti-fracking movement has emerged both interna-tionally with involvement of international environmentalorganizations and nation states such as France and locallyin affected areas such as Balcombe in Sussex where theBalcombe drilling protest was in progress during summer2013.[118] The considerable opposition against hydraulicfracturing activities in local townships in the United Stateshas led companies to adopt a variety of public rela-tions measures to assuage fears about hydraulic fractur-ing, including the admitted use of “mil i tary tac tics tocounter drilling oppo nents”. At a conference where pub-lic relations measures were discussed, a senior execu-tive at Anadarko Petroleum was recorded on tape say-ing, “Download the US Army / Marine Corps Counterin-surgency Manual, because we are dealing with an in-surgency”, while referring to hydraulic fracturing oppo-nents. Matt Pitzarella, spokesman for Range Resourcesalso told other conference attendees that Range employedpsychological warfare operations veterans. According toPitzarella, the experience learned in the Middle East hasbeen valuable to Range Resources in Pennsylvania, whendealing with emotionally charged township meetings andadvising townships on zoning and local ordinances deal-ing with hydraulic fracturing.[119][120]

Police officers in the United States have been forcedto deal with intentionally disruptive and even poten-tially violent opposition to oil and gas development. InMarch 2013, ten people were arrested[121] during an“anti-fracking protest” near New Matamoras, Ohio, af-ter they illegally entered a development zone and latchedthemselves to drilling equipment. In northwest Pennsyl-vania, there was a drive-by shooting at a well site, inwhich an individual shot two rounds of a small-caliberrifle in the direction of a drilling rig, just before shout-ing profanities at the site and fleeing the scene.[122] InWashington County, Pennsylvania, a contractor workingon a gas pipeline found a pipe bomb that had been placedwhere a pipeline was to be constructed, which local au-thorities said would have caused a “catastrophe” had theynot discovered and detonated it.[123]

In 2014 a number of officials in Europe and NATO pro-vided circumstantial evidence that protests against frack-ing may be sponsored by Gazprom. Russian officialshave on numerous occasions warned Europe that fracking“poses a huge environmental problem”. At the same timeGazprom is also searching for shale gas in Romania (viaits subsidiary “Nis”) and it has always aggressively reactedto any criticism by environmental organisations.[124]

8.2 Media coverage

Josh Fox’s 2010 Academy Award nominated filmGasland [125] became a center of opposition to hydraulicfracturing of shale. The movie presented problems withground water contamination near well sites in Pennsylva-

10 10 REFERENCES

nia, Wyoming, and Colorado.[126] Energy in Depth, an oiland gas industry lobbying group, called the film’s factsinto question.[127] In response, a rebuttal of Energy inDepth's claims of inaccuracy was posted on Gasland’swebsite.[128]

The Director of the Colorado Oil and Gas ConservationCommission (COGCC) offered to be interviewed as partof the film if he could review what was included from theinterview in the final film but Fox declined the offer.[129]

Exxon Mobil, Chevron Corporation and ConocoPhillipsaired advertisements during 2011 and 2012 that claimedto describe the economic and environmental benefitsof natural gas and argue that hydraulic fracturing wassafe.[130]

The film Promised Land, starring Matt Damon, takes onhydraulic fracturing.[131] The gas industry is making plansto try to counter the film’s criticisms of hydraulic fractur-ing with informational flyers, and Twitter and Facebookposts.[130]

On January 22, 2013 Northern Irish journalist and film-maker Phelim McAleer released a crowdfunded[132] doc-umentary called FrackNation as a response to the state-ments made by Fox in Gasland. FrackNation premieredon Mark Cuban's AXS TV. The premiere correspondedwith the release of Promised Land.[133]

On April 21, 2013, Josh Fox released Gasland 2, a doc-umentary that states that the gas industry’s portrayal ofnatural gas as a clean and safe alternative to oil is a myth,and that hydraulically fractured wells inevitably leak overtime, contaminating water and air, hurting families, andendangering the earth’s climate with the potent green-house gas methane.

8.3 Research issues

Typically the funding source of the research studies is afocal point of controversy. Concerns have been raisedabout research funded by foundations and corporations,or by environmental groups, which can at times lead toat least the appearance of unreliable studies.[134][135] Sev-eral organizations, researchers, and media outlets have re-ported difficulty in conducting and reporting the resultsof studies on hydraulic fracturing due to industry[136] andgovernmental pressure,[10] and expressed concern overpossible censoring of environmental reports.[136][137][138]

Researchers have recommended requiring disclosure ofall hydraulic fracturing fluids, testing animals raisednear fracturing sites, and closer monitoring of envi-ronmental samples.[139] There is a need for more re-search into the environmental and health effects of thetechnique.[96][140][141][142]

9 See also

• Directional drilling

• Environmental concerns with electricity generation

• Environmental impact of hydraulic fracturing

• Environmental impact of petroleum

• Environmental impact of the oil shale industry

• ExxonMobil Electrofrac

• Hydraulic fracturing by country

• Hydraulic fracturing in the United States

• In-situ leach

10 References[1] Blundell D., (2005). “Processes of tectonism, magmatism

and mineralization: Lessons from Europe”. Ore GeologyReviews 27: 340.

[2] Charlez, Philippe A. (1997). Rock Mechanics: PetroleumApplications. Paris: Editions Technip. p. 239. ISBN9782710805861. Retrieved 2012-05-14.

[3] King, George E (2012), Hydraulic fracturing 101 (PDF),Society of Petroleum Engineers, Paper 152596

[4] Staff. “State by state maps of hydraulic fracturing in US.”.Fractracker.org. Retrieved 19 October 2013.

[5] IEA (29 May 2012). Golden Rules for a Golden Age ofGas. World Energy Outlook Special Report on Unconven-tional Gas (PDF). OECD. pp. 18–27.

[6] Hillard Huntington et al. EMF 26: Changing the Game?Emissions and Market Implications of New Natural GasSupplies Report. Stanford University. Energy ModelingForum, 2013.

[7] Brown, Valerie J. (February 2007). “Industry Issues:Putting the Heat on Gas”. Environmental Health Perspec-tives (US National Institute of Environmental Health Sci-ences) 115 (2): A76. doi:10.1289/ehp.115-a76. PMC1817691. PMID 17384744. Retrieved 2012-05-01.

[8] Kim, Won-Young 'Induced seismicity associated withfluid injection into a deep well in Youngstown, Ohio',Journal of Geophysical Research-Solid Earth

[9] US Geological Survey, Produced water, overview, ac-cessed 8 Nov. 2014.

[10] Jared Metzker (7 August 2013). “Govt, Energy IndustryAccused of Suppressing Fracking Dangers”. Inter PressService. Retrieved 28 December 2013.

[11] Patel, Tara (31 March 2011). “The French Public Says Noto ' Le Fracking ' ". Bloomberg Businessweek. Retrieved 22February 2012.

11

[12] Patel, Tara (4 October 2011). “France to Keep FrackingBan to Protect Environment, Sarkozy Says”. BloombergBusinessweek. Retrieved 22 February 2012.

[13] “Commission recommendation on minimum principlesfor the exploration and production of hydrocarbons (suchas shale gas) using high-volume hydraulic fracturing(2014/70/EU)". Official Journal of the European Union.22 January 2014. Retrieved 13 March 2014.

[14] Fjaer, E. (2008). “Mechanics of hydraulic fracturing”.Petroleum related rock mechanics. Developments inpetroleum science (2nd ed.). Elsevier. p. 369. ISBN978-0-444-50260-5. Retrieved 2012-05-14.

[15] Price, N. J.; Cosgrove, J. W. (1990). Analysis of geolog-ical structures. Cambridge University Press. pp. 30–33.ISBN 978-0-521-31958-4. Retrieved 5 November 2011.

[16] Manthei, G.; Eisenblätter, J.; Kamlot, P. (2003). “Stressmeasurement in salt mines using a special hydraulic frac-turing borehole tool”. In Natau, Fecker & Pimentel.Geotechnical Measurements and Modelling (PDF). pp.355–360. ISBN 90-5809-603-3. Retrieved 6 March2012.

[17] Zoback, M.D. (2007). Reservoir geomechanics. Cam-bridge University Press. p. 18. ISBN 9780521146197.Retrieved 6 March 2012.

[18] Laubach, S. E.; Reed, R. M.; Olson, J. E.; Lan-der, R. H.; Bonnell, L. M. (2004). “Coevolution ofcrack-seal texture and fracture porosity in sedimentaryrocks: cathodoluminescence observations of regionalfractures”. Journal of Structural Geology (Elsevier)26 (5): 967–982. Bibcode:2004JSG....26..967L.doi:10.1016/j.jsg.2003.08.019. Retrieved 5 November2011.

[19] Sibson, R. H.; Moore, J.; Rankin, A. H. (1975). “Seismicpumping--a hydrothermal fluid transport mechanism”.Journal of the Geological Society (London: Geological So-ciety) 131 (6): 653–659. doi:10.1144/gsjgs.131.6.0653.(subscription required). Retrieved 5 November 2011.

[20] Gill, R. (2010). Igneous rocks and processes: a practicalguide. John Wiley and Sons. p. 102. ISBN 978-1-4443-3065-6. Retrieved 5 November 2011.

[21] “Shooters – A “Fracking” History”. American Oil & GasHistorical Society. Retrieved 12 October 2014.

[22] “Acid fracturing”. Society of Petroleum Engineers. Re-trieved 12 October 2014.

[23] Montgomery, Carl T.; Smith, Michael B. (December2010). “Hydraulic fracturing. History of an enduringtechnology” (PDF). JPT Online (Society of Petroleum En-gineers): 26–41. Retrieved 13 May 2012.

[24] Energy Institute (February 2012) (PDF). Fact-BasedRegulation for Environmental Protection in Shale GasDevelopment (Report). University of Texas atAustin. http://cewc.colostate.edu/wp-content/uploads/2012/02/ei_shale_gas_regulation120215.pdf. Retrieved29 February 2012.

[25] A. J. Stark, A. Settari, J. R. Jones, Analysis of HydraulicFracturing of High Permeability Gas Wells to ReduceNon-darcy Skin Effects, Petroleum Society of Canada,Annual Technical Meeting, Jun 8 - 10, 1998, Calgary, Al-berta.

[26] Mader, Detlef (1989). Hydraulic Proppant Fracturing andGravel Packing. Elsevier. pp. 173–174; 202. ISBN9780444873521.

[27] Ben E. Law and Charles W. Spencer, 1993, “Gas in tightreservoirs-an emerging major source of energy,” in DavidG. Howell (ed.), The Future of Energy Gasses, US Geo-logical Survey, Professional Paper 1570, p.233-252.

[28] C.R. Fast, G.B. Holman, and R. J. Covlin, “The applica-tion of massive hydraulic fracturing to the tight Muddy'J' Formation, Wattenberg Field, Colorado,” in Harry K.Veal, (ed.), Exploration Frontiers of the Central and South-ern Rockies (Denver: Rocky Mountain Association of Ge-ologists, 1977) 293-300.

[29] Robert Chancellor, “Mesaverde hydraulic fracture stim-ulation, northern Piceance Basin - progress report,” inHarry K. Veal, (ed.), Exploration Frontiers of the Centraland Southern Rockies (Denver: Rocky Mountain Associ-ation of Geologists, 1977) 285-291.

[30] C.E Bell and others, Effective diverting in horizontal wellsin the Austin Chalk, Society of Petroleum Engineers con-ference paper, 1993.

[31] Robbins K. (2013). Awakening the Slumbering Giant:How Horizontal Drilling Technology Brought the Endan-gered Species Act to Bear on Hydraulic Fracturing. CaseWestern Reserve Law Review.

[32] US Dept. of Energy, How is shale gas produced?, Apr.2013.

[33] United States National Research Council, Committee toReview the Gas Research Institute’s Research, Develop-ment and Demonstration Program, Gas Research Institute(1989). A review of the management of the Gas ResearchInstitute. National Academies. p. ?.

[34] “US Government Role in Shale Gas Fracking: AnOverview”

[35] SPE production & operations 20. Society of PetroleumEngineers. 2005. p. 87.

[36] The Breakthrough Institute. Interview with Dan Steward,former Mitchell Energy Vice President. December 2011.

[37] Zuckerman, Gregory. “How fracking billionaires builttheir empires”. Quartz. The Atlantic Media Company.Retrieved 15 November 2013.

[38] Wasley, Andrew (1 March 2013) On the frontline ofPoland’s fracking rush The Guardian, Retrieved 3 March2013

[39] (7 August 2012) JKX Awards Fracking Contract forUkrainian Prospect Natural Gas Europe, Retrieved 3March 2013

12 10 REFERENCES

[40] (18 February 2013) Turkey’s shale gas hopes draw grow-ing interest Reuters, Retrieved 3 March 2013

[41] “Hydraulic fracturing research study” (PDF). EPA. June2010. EPA/600/F-10/002. Retrieved 2012-12-26.

[42] Ground Water Protection Council; ALL Consulting(April 2009) (PDF). Modern Shale Gas Develop-ment in the United States: A Primer (Report).DOE Office of Fossil Energy and National EnergyTechnology Laboratory. pp. 56–66. DE-FG26-04NT15455. http://energy.gov/sites/prod/files/2013/03/f0/ShaleGasPrimer_Online_4-2009.pdf. Retrieved 24February 2012.

[43] Penny, Glenn S.; Conway, Michael W.; Lee, Wellington(June 1985). “Control and Modeling of Fluid LeakoffDuring Hydraulic Fracturing”. Journal of PetroleumTechnology (Society of Petroleum Engineers) 37 (6):1071–1081. doi:10.2118/12486-PA. Retrieved 2012-05-10.

[44] Arthur, J. Daniel; Bohm, Brian; Coughlin, Bobbi Jo;Layne, Mark (2008) (PDF). Hydraulic Fracturing Con-siderations for Natural Gas Wells of the Fayetteville Shale(Report). ALL Consulting. p. 10. http://www.aogc.state.ar.us/ALL%20FayettevilleFrac%20FINAL.pdf. Re-trieved 2012-05-07.

[45] Chilingar, George V.; Robertson, John O.; Kumar, San-jay (1989). Surface Operations in Petroleum Production 2.Elsevier. pp. 143–152. ISBN 9780444426772.

[46] Love, Adam H. (December 2005). “Fracking: The Con-troversy Over its Safety for the Environment”. JohnsonWright, Inc. Retrieved 2012-06-10.

[47] “Hydraulic Fracturing”. University of Colorado LawSchool. Retrieved 2 June 2012.

[48] Wan Renpu (2011). Advanced Well Completion Engi-neering. Gulf Professional Publishing. p. 424. ISBN9780123858689.

[49] Andrews, Anthony et al. (30 October 2009) (PDF). Un-conventional Gas Shales: Development, Technology, andPolicy Issues (Report). Congressional Research Service.pp. 7; 23. http://www.fas.org/sgp/crs/misc/R40894.pdf.Retrieved 22 February 2012.

[50] Ram Narayan (August 8, 2012). “From Food to Frack-ing: Guar Gum and International Regulation”. RegBlog.University of Pennsylvania Law School. Retrieved 15 Au-gust 2012.

[51] 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.

[52] “Freeing Up Energy. Hydraulic Fracturing: Unlock-ing America’s Natural Gas Resources” (PDF). AmericanPetroleum Institute. 2010-07-19. Retrieved 2012-12-29.

[53] Brainard, Curtis (June 2013). “The Future of Energy”.Popular Science Magazine. p. 59. Retrieved 1 January2014.

[54] “CARBO ceramics”. Retrieved 2011.

[55] (PDF) Chemicals Used in Hydraulic Fracturing(Report). Committee on Energy and Commerce U.S.House of Representatives. April 18, 2011. p. ?.http://democrats.energycommerce.house.gov/sites/default/files/documents/Hydraulic%20Fracturing%20Report%204.18.11.pdf.

[56] ALL Consulting (June 2012) (PDF). The ModernPractices of Hydraulic Fracturing: A Focus on Cana-dian Resources (Report). Canadian Association ofPetroleum Producers. http://www.capp.ca/getdoc.aspx?DocId=210903&DT=NTV. Retrieved 2012-08-04.

[57] Reis, John C. (1976). Environmental Control in PetroleumEngineering. Gulf Professional Publishers.

[58] (PDF) Radiation Protection and the Management of Ra-dioactive Waste in the Oil and Gas Industry (Report).International Atomic Energy Agency. 2003. pp. 39–40. http://www-pub.iaea.org/MTCD/publications/PDF/Pub1171_web.pdf. Retrieved 20 May 2012. “Beta emit-ters, including 3H and 14C, may be used when it is fea-sible to use sampling techniques to detect the presenceof the radiotracer, or when changes in activity concentra-tion can be used as indicators of the properties of inter-est in the system. Gamma emitters, such as 46Sc, 140La,56Mn, 24Na, 124Sb, 192Ir, 99Tcm, 131I, 110Agm, 41Ar and133Xe are used extensively because of the ease with whichthey can be identified and measured. ... In order to aidthe detection of any spillage of solutions of the 'soft' betaemitters, they are sometimes spiked with a short half-lifegamma emitter such as 82Br”

[59] Jack E. Whitten, Steven R. Courtemanche, Andrea R.Jones, Richard E. Penrod, and David B. Fogl (Di-vision of Industrial and Medical Nuclear Safety, Of-fice of Nuclear Material Safety and Safeguards) (June2000). “Consolidated Guidance About Materials Li-censes: Program-Specific Guidance About Well Logging,Tracer, and Field Flood Study Licenses (NUREG-1556,Volume 14)". US Nuclear Regulatory Commission. Re-trieved 19 April 2012. labeled Frac Sand...Sc-46, Br-82,Ag-110m, Sb-124, Ir-192

[60] Bennet, Les, et al. “The Source for Hydraulic FractureCharacterization” (PDF). Oilfield Review (Schlumberger)(Winter 2005/2006): 42–57. Retrieved 2012-09-30.

[61] Fehler, Michael C. (1989). “Stress Control of seismic-ity patterns observed during hydraulic fracturing experi-ments at the Fenton Hill hot dry rock geothermal energysite, New Mexico”. International Journal of Rock Me-chanics and Mining Sciences & Geomechanics Abstracts.3 26. doi:10.1016/0148-9062(89)91971-2. Retrieved 1January 2014.

[62] Le Calvez, Joel (2007). “Real-time microseismic moni-toring of hydraulic fracture treatment: A tool to improvecompletion and reservoir management”. SPE HydraulicFracturing Technology Conference.

[63] Cipolla, Craig (2010). “Hydraulic Fracture Monitoring toReservoir Simulation: Maximizing Value”. SPE AnnualTechnical Conference and Exhibition. Retrieved 1 January2014.

13

[64] Seale, Rocky (July–August 2007). “Open hole comple-tion systems enables multi-stage fracturing and stimula-tion along horizontal wellbores” (PDF). Drilling Contrac-tor (Fracturing stimulation ed.). Retrieved October 1,2009.

[65] “Completion Technologies”. EERC. Retrieved 2012-09-30.

[66] “Energy from Shale”. 2011.

[67] Mooney, Chris (2011). “The Truth AboutFracking”. Scientific American 305 (305):80–85. Bibcode:2011SciAm.305d..80M.doi:10.1038/scientificamerican1111-80.

[68] “The Barnett Shale” (PDF). North Keller Neighbors To-gether. Retrieved 2012-05-14.

[69] David Wethe (19 January 2012). “Like Fracking? You'llLove 'Super Fracking'". Businessweek. Retrieved 22 Jan-uary 2012.

[70] “Production Decline of a Natural Gas Well Over Time”.Geology.com. The Geology Society of America. 3 Jan-uary 2012. Retrieved 4 March 2012.

[71] Economides, Michael J. (2000). Reservoir stimulation. J.Wiley. p. P-2. ISBN 9780471491927.

[72] Gidley, John L. (1989). Recent Advances in HydraulicFracturing. SPE Monograph 12. SPE. p. ?. ISBN9781555630201.

[73] Ching H. Yew (1997). Mechanics of Hydraulic Frac-turing. Gulf Professional Publishing. p. ?. ISBN9780884154747.

[74] Banks, David; Odling, N. E.; Skarphagen, H.; Rohr-Torp,E. (May 1996). “Permeability and stress in crystallinerocks”. Terra Nova 8 (3): 223–235. doi:10.1111/j.1365-3121.1996.tb00751.x.

[75] Brown, Edwin Thomas (2007) [2003]. Block Caving Ge-omechanics (2nd ed.). Indooroopilly, Queensland: JuliusKruttschnitt Mineral Research Centre, UQ. ISBN 978-0-9803622-0-6. Retrieved 2012-05-14.

[76] Frank, U.; Barkley, N. (February 1995). “Soil Reme-diation: Application of Innovative and Standard Tech-nologies”. Journal of Hazardous Materials 40 (2): 191–201. doi:10.1016/0304-3894(94)00069-S. ISSN 0304-3894. |chapter= ignored (help) (subscription required)

[77] Bell, Frederic Gladstone (2004). Engineering Geologyand Construction. Taylor & Francis. p. 670. ISBN9780415259392.

[78] Aamodt, R. Lee; Kuriyagawa, Michio (1983). “Mea-surement of Instantaneous Shut-In Pressure in Crys-talline Rock”. Hydraulic fracturing stress measurements.National Academies. p. 139.

[79] “Geothermal Technologies Program: How an EnhancedGeothermal System Works”. eere.energy.gov. 2011-02-16. Retrieved 2011-11-02.

[80] Miller, Bruce G. (2005). Coal Energy Systems. Sustain-able World Series. Academic Press. p. 380. ISBN9780124974517.

[81] Waltz, James; Decker, Tim L (1981), “Hydro-fracturingoffers many benefits”, Johnson Driller’s Journal (2ndquarter): 4–9

[82] Williamson, WH (1982), “The use of hydraulic tech-niques to improve the yield of bores in fractured rocks”,Groundwater in Fractured Rock, Conference Series (5),Australian Water Resources Council

[83] Less, C; Andersen, N (Feb 1994), “Hydrofracture: stateof the art in South Africa”, Applied Hydrogeology: 59–63

[84] National Petroleum Council, Prudent Development: Real-izing the Potential of North America’s Abundant NaturalGas and Oil Resources, September 15, 2011.

[85] IHS Global Insight, Measuring the Economic and EnergyImpacts of Proposals to Regulate Hydraulic Fracturing,2009.

[86] Asian Refiners Get Squeezed by U.S. Energy Boom, WallStreet Journal, Jan. 1, 2014

[87] Spencer T, Sartor O, Mathieu M “Unconventional wis-dom: an economic analysis of US shale gas and implica-tions for the EU”, IDDRI, Paris, France, February 2014

[88] Fracking Growth - Estimating the Economic Impact ofShale Oil and Gas Development in the US, Fetzer, Thiemo(2014)

[89] Dutch Disease or Agglomeration? The Local EconomicEffects of Natural Resource Booms in Modern America,Alcott and Kenniston (2013)

[90] The housing market impacts of shale gas development”,by Lucija Muehlenbachs, Elisheba Spiller and ChristopherTimmins. NBER Working Paper 19796, January 2014.

[91] Broomfield, Mark (2012-08-10) (PDF). Support tothe identification of potential risks for the environ-ment and human health arising from hydrocarbonsoperations involving hydraulic fracturing in Europe(Report). European Commission. pp. vi–xvi.ED57281. http://ec.europa.eu/environment/integration/energy/pdf/fracking%20study.pdf. Retrieved 2014-09-29.

[92] “Air Quality”. DECC.

[93] Abdalla, Charles W.; Drohan, Joy R. (2010) (PDF).Water Withdrawals for Development of Marcellus ShaleGas in Pennsylvania. Introduction to Pennsylvania’s Wa-ter Resources (Report). The Pennsylvania State Univer-sity. http://pubs.cas.psu.edu/FreePubs/pdfs/ua460.pdf.Retrieved 16 September 2012. “Hydrofracturing a hori-zontal Marcellus well may use 4 to 8 million gallons of wa-ter, typically within about 1 week. However, based on ex-periences in other major U.S. shale gas fields, some Mar-cellus wells may need to be hydrofractured several timesover their productive life (typically five to twenty years ormore)"

14 10 REFERENCES

[94] Faucon, Benoît (17 September 2012). “Shale-Gas BoomHits Eastern Europe”. WSJ.com. Retrieved 17 Septem-ber 2012.

[95] New Research of Surface Spills in Fracking Industry.(2013). Professional Safety, 58(9), 18.

[96] Public Health England. 25 June 2014 PHE-CRCE-009:Review of the potential public health impacts of exposuresto chemical and radioactive pollutants as a result of shalegas extraction ISBN 978-0-85951-752-2

[97] Logan, Jeffrey (2012) (PDF). Natural Gas and the Trans-formation of the U.S. Energy Sector: Electricity (Re-port). Joint Institute for Strategic Energy Analysis. http://www.nrel.gov/docs/fy13osti/55538.pdf. Retrieved 27March 2013.

[98] Köster, Vera. “What is Shale Gas? How Does FrackingWork?". www.chemistryviews.org. Retrieved 4 Decem-ber 2014.

[99] Zoback, Mark; Kitasei, Saya; Copithorne, Brad (July2010) (PDF). Addressing the Environmental Risks fromShale Gas Development (Report). Worldwatch Institute.p. 9. http://www.worldwatch.org/files/pdf/Hydraulic%20Fracturing%20Paper.pdf. Retrieved 2012-05-24.

[100] Begley, Sharon; McAllister, Edward (12 July 2013).“News in Science: Earthquakes may trigger frackingtremors”. ABC Science (Reuters). Retrieved 17 Decem-ber 2013.

[101] “Fracking tests near Blackpool 'likely cause' of tremors”.BBC News. 2 November 2011. Retrieved 22 February2012.

[102] Frederick J. Herrmann, Federal Railroad Administration,letter to American Petroleum Institute, 17 July 2013, p.4.

[103] Nolon, John R.; Polidoro, Victoria (2012).“Hydrofracking: Disturbances Both Geological andPolitical: Who Decides?" (PDF). The Urban Lawyer 44(3): 1–14. Retrieved 2012-12-21.

[104] Negro, Sorrell E. (February 2012). “Fracking Wars: Fed-eral, State, and Local Conflicts over the Regulation of Nat-ural Gas Activities” (PDF). Zoning and Planning Law Re-port (Thomson Reuters) 35 (2): 1–14. Retrieved 2014-05-01.

[105] “LOI n° 2011-835 du 13 juillet 2011 visant à interdirel'exploration et l'exploitation des mines d'hydrocarburesliquides ou gazeux par fracturation hydraulique et à ab-roger les permis exclusifs de recherches comportant desprojets ayant recours à cette technique”

[106] “Article L 110-1 du Code de l'Environnement”

[107] “Fracking ban upheld by French court”. BBC. 11 October2013. Retrieved 16 October 2013.

[108] Moore, Robbie. “Fracking, PR, and the Greening ofGas”. The International. Retrieved 16 March 2013.

[109] Bakewell, Sally (13 December 2012). “U.K. GovernmentLifts Ban on Shale Gas Fracking”. Bloomberg. Retrieved26 March 2013.

[110] Hweshe, Francis (17 September 2012). “South Africa:International Groups Rally Against Fracking, TKAGClaims”. West Cape News. Retrieved 11 February 2014.

[111] Nicola, Stefan; Andersen, Tino (26 February 2013).“Germany agrees on regulations to allow fracking for shalegas”. Bloomberg. Retrieved 1 May 2014.

[112] Healy, Dave (July 2012) (PDF). Hydraulic Frac-turing or 'Fracking': A Short Summary of Cur-rent Knowledge and Potential EnvironmentalImpacts (Report). Environmental ProtectionAgency. http://www.epa.ie/pubs/reports/research/sss/UniAberdeen_FrackingReport.pdf. Retrieved 28July 2013.

[113] Hass, Benjamin (14 August 2012). “Fracking HazardsObscured in Failure to Disclose Wells”. Bloomberg. Re-trieved 27 March 2013.

[114] Soraghan, Mike (13 December 2013). “White House of-ficial backs FracFocus as preferred disclosure method”.E&E News. Retrieved 27 March 2013.

[115] , Environmental Protection Agency

[116] Editorial Board (December 17, 2014). “Gov. CuomoMakes Sense on Fracking”. New York Times. RetrievedDecember 18, 2014.

[117] http://www.timesunion.com/local/article/State-1st-in-U-S-to-ban-fracking-5964402.php

[118] Jan Goodey (1 August 2013). “The UK’s anti frackingmovement is growing”. The Ecologist. Retrieved July 29,2013.

[119] Javers, Eamon (8 Nov 2011). “Oil Executive: Military-Style 'Psy Ops’ Experience Applied”. CNBC.

[120] Phillips, Susan (9 Nov 2011). "'We're Dealing with an In-surgency,' says Energy Company Exec of Fracking Foes”.National Public Radio.

[121] Palmer, Mike (27 March 2013). “Oil-gas boom spawnsHarrison safety talks”. Times Leader. Retrieved 27 March2013.

[122] “Shots fired at W. Pa. gas drilling site”. Philadelphia In-quirer. 12 March 2013. Retrieved 27 March 2013.

[123] Detrow, Scott (15 August 2012). “Pipe Bomb Found NearAllegheny County Pipeline”. NPR. Retrieved 27 March2013.

[124] Andrew Higgins (2014-11-30). “Russian Money Sus-pected Behind Fracking Protests”. New York Times. Re-trieved 2014-12-04.

[125] Documentary: Gasland (2010). 104 minutes.

[126] “Gasland”. 2010. Retrieved 2012-05-14.

[127] “Gasland Debunked” (PDF). Energy in Depth. Retrieved2012-05-14.

[128] “Affirming Gasland”. July 2010. Retrieved 2010-12-21.

15

[129] COGCC Gasland Correction Document Colorado De-partment of Natural Resources October 29, 2010

[130] Gilbert, Daniel (7 October 2012). “Matt Damon Frack-ing Film Lights Up Petroleum Lobby”. The Wall StreetJournal ((subscription required)). Retrieved 26 Decem-ber 2012.

[131] Gerhardt, Tina (31 December 2012). “Matt Damon Ex-poses Fracking in Promised Land”. The Progressive. Re-trieved 4 January 2013.

[132] Kickstarter, FrackNation by Ann and Phelim Media LLC,April 6, 2012

[133] The Hollywood Reporter, Mark Cuban’s AXS TV PicksUp Pro-Fracking Documentary 'FrackNation', December17, 2012

[134] Deller, Steven; Schreiber, Andrew (2012). “Mining andCommunity Economic Growth” (PDF). The Review ofRegional Studies 42: 121–141. Retrieved 3 March 2013.

[135] Soraghan, Mike (12 March 2012). “Quiet foundationfunds the 'anti-fracking' fight”. E&E News. Retrieved 27March 2013. In our work to oppose fracking, the ParkFoundation has simply helped to fuel an army of coura-geous individuals and NGOs,' or non-governmental orga-nizations, said Adelaide Park Gomer, foundation presi-dent and Park heir, in a speech late last year.

[136] Urbina, Ian (3 March 2011). “Pressure Limits Efforts toPolice Drilling for Gas”. The New York Times. Retrieved23 February 2012. More than a quarter-century of ef-forts by some lawmakers and regulators to force the fed-eral government to police the industry better have beenthwarted, as E.P.A. studies have been repeatedly nar-rowed in scope and important findings have been removed

[137] “The Debate Over the Hydrofracking Study’s Scope”. TheNew York Times. 3 March 2011. Retrieved 1 May2012. While environmentalists have aggressively lobbiedthe agency to broaden the scope of the study, industry haslobbied the agency to narrow this focus

[138] “Natural Gas Documents”. The New York Times. 27February 2011. Retrieved 5 May 2012. The Times re-viewed more than 30,000 pages of documents obtainedthrough open records requests of state and federal agen-cies and by visiting various regional offices that overseedrilling in Pennsylvania. Some of the documents wereleaked by state or federal officials.

[139] Ramanuja, Krishna (7 March 2012). “Study suggests hy-drofracking is killing farm animals, pets”. Cornell Chron-icle (Cornell University). Retrieved 9 March 2012.

[140] Drajem, Mark (11 January 2012). “Fracking PoliticalSupport Unshaken by Doctors’ Call for Ban”. Bloomberg.Retrieved 19 January 2012.

[141] Alex Wayne (4 January 2012). “Health Effects of Frack-ing Need Study, Says CDC Scientist”. Bloomberg Busi-nessweek. Retrieved 29 February 2012.

[142] Finkel ML, Hays J (October 2013). “The implicationsof unconventional drilling for natural gas: a global publichealth concern”. Public Health (Review) 127 (10): 889–93. doi:10.1016/j.puhe.2013.07.005. PMID 24119661.

11 External links• Natural Gas Extraction—Hydraulic Fracturing

(EPA website)

• EPA’s Draft Hydraulic Fracturing Study Plan

• The British Columbia (Canada) Oil and Gas Com-mission mandatory disclosure of hydraulic fractur-ing fluids

• Hydraulic Fracturing: Selected Legal IssuesCongressional Research Service

• Fracking collected news and commentary atProPublica

• Hydraulic Fracturing at Earthworks

• FracFocus Searchable database with chemical com-position of fracking fluid of individual wells

• FracTracker.org: Maps, data, and articles fromnews, government, industry, and academic sources.

• 60 Minutes Report on Hydraulic Fracturing.

12 Further reading• Kiparsky, Michael; Hein, Jayni Foley (April 2013).

“Regulation of Hydraulic Fracturing in Califor-nia: A Wastewater and Water Quality Perspective”(PDF). University of California Center for Law, En-ergy, and the Environment. Retrieved 2014-05-01.

• Ridlington, Elizabeth; John Rumpler (October 3,2013). “Fracking by the numbers”. EnvironmentAmerica.

• “DISH, TExas Exposure Investigation”. TexasDSHS. Retrieved 27 March 2013.

• de Pater, C.J.; Baisch, S. (2 November 2011)(PDF). Geomechanical Study of Bow-land Shale Seismicity (Report). CuadrillaResources. http://www.cuadrillaresources.com/wp-content/uploads/2012/02/Geomechanical-Study-of-Bowland-Shale-Seismicity_02-11-11.pdf. Retrieved 22 February 2012.

• McKenzie, Lisa; Witter, Roxana; Newman,Lee; Adgate, John (2012). “Human health riskassessment of air emissions from developmentof unconventional natural gas resources”. Sci-ence of the Total Environment 424: 79–87.doi:10.1016/j.scitotenv.2012.02.018. PMID22444058.

• “The Hydraulic Fracturing Water Cycle”. EPA. 16March 2014. Retrieved 2014-10-10.

16 12 FURTHER READING

• Fernandez, John Michael; Gunter, Matthew.“Hydraulic Fracturing: Environmentally FriendlyPractices” (PDF). Houston Advanced ResearchCenter. Retrieved 2012-12-29.

• Colborn, Theo; Kwiatkowski, Carol; Schultz,Kim; Bachran, Mary (2011). “Natural gasoperations from public health perspective”.Human and Ecological Risk Assessment: anInternational Journal 17 (5): 1039–1056.doi:10.1080/10807039.2011.605662.

• Abdalla, Charles W.; Drohan, Joy R.; Blunk, Kris-ten Saacke; Edson, Jessie (2014) (PDF). MarcellusShale Wastewater Issues in Pennsylvania—Current and Emerging Treatment and DisposalTechnologies (Report). Penn State Extension.http://extension.psu.edu/natural-resources/water/marcellus-shale/waste-water/current-and-emerging-treatment-and-disposal-technologies.Retrieved 2014-10-11.

• Arthur, J. Daniel; Langhus, Bruce; Alleman, David(2008) (PDF). An overview of modern shale gasdevelopment in the United States (Report). ALLConsulting. p. 21. http://www.lexisnexis.com/documents/pdf/20100210093849_large.pdf. Re-trieved 2012-05-07.

• Molofsky, L. J.; Connor, J. A.; Shahla, K. F.; Wylie,A. S.; Wagner, T. (December 5, 2011). “Methanein Pennsylvania Water Wells Unrelated to MarcellusShale Fracturing”. Oil and Gas Journal (PennwellCorporation) 109 (49): 54–67.

• IEA (2011). World Energy Outlook 2011. OECD.pp. 91; 164. ISBN 9789264124134.

• “How is hydraulic fracturing related to earthquakesand tremors?". USGS. Retrieved 4 November 2012.

• Moniz, Ernest J. et al. (June 2011) (PDF).The Future of Natural Gas: An InterdisciplinaryMIT Study (Report). Massachusetts Instituteof Technology. http://mitei.mit.edu/system/files/NaturalGas_Report.pdf. Retrieved 1 June 2012.

• Biello, David (30 March 2010). “Natural gascracked out of shale deposits may mean the U.S. hasa stable supply for a century – but at what cost to theenvironment and human health?". Scientific Amer-ican. Retrieved 23 March 2012.

• Schmidt, Charles (1 August 2011). “Blind Rush?Shale Gas Boom Proceeds Amid Human HealthQuestions”. Environmental Health Perspectives 119(8): a348–a353. doi:10.1289/ehp.119-a348. PMC3237379. PMID 21807583.

• Allen, David T.; Torres, Vincent N.; Thomas,James; Sullivan, David W.; Harrison, Matthew;

Hendler, Al; Herndon, Scott C.; Kolb, CharlesE.; Fraser, Matthew P.; Hill, A. Daniel; Lamb,Brian K.; Miskimins, Jennifer; Sawyer, RobertF.; Seinfeld, John H. (16 September 2013).“Measurements of methane emissions at naturalgas 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, Su-san C. (March 2014). “Estrogen and Andro-gen Receptor Activities of Hydraulic FracturingChemicals and Surface and Ground Water in aDrilling-Dense Region”. Endocrinology 155 (3).doi:10.1210/en.2013-1697. Retrieved 24 Decem-ber 2013.

• Chalupka, S. (October 2012). “OccupationalSilica Exposure in Hydraulic Fracturing”.Workplace Health & Safety 60 (10): 460.doi:10.3928/21650799-20120926-70. Retrieved10 October 2014.

• Smith, S. (1 August 2014). “Respirators Are NotEnough: New Study Examines Worker Exposure toSilica in Hydraulic Fracturing Operations”. EHS To-day. Retrieved 10 October 2014.

• “Waste water (flowback)from hydraulic fracturing”(PDF). Ohio Department of Natural Resources. Re-trieved 29 June 2013.

• Spath, Ph.D., P.E., David P. (November1997) (PDF). Policy Memo 97-005 PolicyGuidance for Direct Domestic Use of Ex-tremely Impaired Sources (Report). Stateof California Department of Health Services.http://www.cdph.ca.gov/certlic/drinkingwater/Documents/DWdocuments/memo97-005.pdf.Retrieved 7 October 2014.

• Weinhold, Bob (19 September 2012). “UnknownQuantity: Regulating Radionuclides in Tap Water”.Environmental Health Perspectives. NIEHS, NIH.Retrieved 11 February 2012. Examples of humanactivities that may lead to radionuclide exposure in-clude mining, milling, and processing of radio activesubstances; wastewater releases from the hydraulicfracturing of oil and natural gas wells... Mining andhydraulic fracturing, or “fracking”, can concentratelevels of uranium (as well as radium, radon, and tho-rium) in wastewater...

• Rachel Maddow, Terrence Henry (7 August 2012).Rachel Maddow Show: Fracking waste messes withTexas (video). MSNBC. Event occurs at 9:24 -10:35.

17

• Cothren, Jackson (PDF). Modeling the Effects ofNon-Riparian Surface Water Diversions on FlowConditions in the Little Red Watershed (Re-port). U. S. Geological Survey, Arkansas WaterScience Center Arkansas Water Resources Center,American Water Resources Association, ArkansasState Section Fayetteville Shale Symposium 2012.p. 12. http://ar.water.usgs.gov/Fayetteville_Shale/abstracts.pdf. Retrieved 16 September 2012."...each well requires between 3 and 7 million gal-lons of water for hydraulic fracturing and the num-ber of wells is expected to grow in the future”

• Janco, David F. (1 February 2007). PADEPDetermination Letter No. 970. Diminution ofSnow Shoe Borough Authority Water Well No.2; primary water source for about 1,000 homesand businesses in and around the borough; con-tested by Range Resources. Determination Let-ter acquired by the Scranton Times-Tribune viaRight-To-Know Law request. (Report). Scran-ton Times-Tribune. http://scrantontimestribune.com/waterproject/970.pdf. Retrieved 27 Decem-ber 2013.

• Janco, David F. (3 January 2008). PADEP De-termination Letter No. 352 Determination Letteracquired by the Scranton Times-Tribune via Right-To-Know Law request. Order: Atlas Miller 42and 43 gas wells; Aug 2007 investigation; sup-plied temporary buffalo for two springs, orderedto permanently replace supplies (Report). Scran-ton Times-Tribune. http://scrantontimestribune.com/waterproject/352.pdf. Retrieved 27 Decem-ber 2013.

• Lustgarten, Abrahm (21 June 2012). “Are Frack-ing Wastewater Wells Poisoning the Ground beneathOur Feet? Leaking injection wells may pose a risk--and the science has not kept pace with the growingglut of wastewater”. Scientific American. Retrieved2014-10-11.

• Rabinowitz, Peter M.; Rabinowitz, Ilya B.; Sli-zovskiy, Vanessa; Lamers, Sally J.; Trufan,Theodore R.; Holford, James D.; Dziura, PeterN.; Peduzzi, Michael J.; Kane, John S.; Reif,John; Weiss, Theresa R.; Stowe1, Meredith H.(2014). “Proximity to Natural Gas Wells andReported Health Status: Results of a House-hold Survey in Washington County, Pennsylva-nia”. Environmental Health Perspectives (US Na-tional Institute of Environmental Health Sciences).doi:10.1289/ehp.1307732. Retrieved 2014-10-07.

• Arthur, J. Daniel; Uretsky, Mike; Wilson, Preston(May 5–6, 2010). “Water Resources and Use forHydraulic Fracturing in the Marcellus Shale Re-gion” (PDF). Meeting of the American Institute of

Professional Geologists. Pittsburgh: ALL Consult-ing. p. 3. Retrieved 2012-05-09.

• Colborn, Theo; Kwiatkowski, Carol; Schultz, Kim;Bachran, Mary (2011). “Natural Gas Operationsfrom a Public Health Perspective” (PDF). Humanand Ecological Risk Assessment: an InternationalJournal (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 accom-panying gas-well drilling and hydraulic fracturing”(PDF). Proceedings of the National Academy of Sci-ences of the United States of America 108 (20):8172–8176. doi:10.1073/pnas.1100682108. Re-trieved 2011-10-14.

18 13 TEXT AND IMAGE SOURCES, CONTRIBUTORS, AND LICENSES

13 Text and image sources, contributors, and licenses

13.1 Text• Hydraulic fracturing Source: http://en.wikipedia.org/wiki/Hydraulic%20fracturing?oldid=638646433 Contributors: Fred Bauder, Ih-

coyc, William M. Connolley, Samw, Hike395, Owen, Lumos3, Bearcat, Rfc1394, Rsduhamel, Alan Liefting, Jeremiah, Ianeiloart, Kravi-etz, GeoGreg, Richardb43, Mike Rosoft, Discospinster, Rich Farmbrough, Kdammers, Vsmith, Smyth, Causa sui, Peter Greenwell,Stesmo, Viriditas, La goutte de pluie, Eric Kvaalen, Sjschen, Velella, Dave.Dunford, Kgrr, BlaiseFEgan, SqueakBox, BD2412, Drbogdan,Rjwilmsi, Jweiss11, Vegaswikian, Mbutts, The wub, Darqcyde, Ground Zero, Kolbasz, Sgartner, Guanxi, DVdm, Bgwhite, Ahpook, Wave-length, Scott Teresi, Jimp, Arzel, DMahalko, Casey56, Rsrikanth05, Morphh, NawlinWiki, Keithonearth, Abrunete, Trovatore, Dhollm,Wknight94, Bdell555, Arthur Rubin, Tomhanna, Dspradau, Wizofaus, Luk, A13ean, MartinGugino, Timeshifter, Kintetsubuffalo, Mauls,Gilliam, Ohnoitsjamie, Chris the speller, Thumperward, Abandon all arr now, Victorgrigas, Deli nk, Solarix, Racklever, VMS Mosaic,Robma, BullRangifer, Fuzzypeg, Mwtoews, Salamurai, Captainbeefart, BrownHairedGirl, Evenios, Noegenesis, NYCJosh, Peterlewis,IronGargoyle, Pjrm, Ricmcc1766, Blackash, Ian peters, CmdrObot, Cartoonmaster, Cooljeanius, MC10, Gogo Dodo, Christian75, Kckid,NorthernThunder, Mglovesfun, Epbr123, Cimbalom, Wikid77, Martin Hogbin, Headbomb, Vertium, Hcobb, Dawnseeker2000, Seaphoto,Blue Tie, SummerPhD, Prolog, Tillman, Lfstevens, Daytona2, Mikenorton, JamesBWatson, Harel, Prestonmcconkie, The Anomebot2,Beagel, Sustainableyes, JaGa, VetPsychWars, Mschiffler, Gandydancer, Uriel8, R'n'B, CommonsDelinker, Tgeairn, Rlsheehan, Peter Chas-tain, RTBoyce, Arms & Hearts, KylieTastic, Tiggerjay, Equazcion, Reelrt, Vranak, 28bytes, Tourbillon, Kriplozoik, BoogaLouie, Lexein,Mcewan, Philip Trueman, Piperh, Oxfordwang, T0pher17, Aondotri, Onore Baka Sama, Plazak, Meters, Lamro, Antillarum, SylviaS-tanley, Biscuittin, Swliv, Ketone16, Toddst1, Alexbrn, Rexpilger, Yone Fernandes, William D. Walker, Msiner, FghIJklm, Denisarona,Aichik, Mrfebruary, NickCT, General Epitaph, ImperfectlyInformed, JTSchreiber, Niceguyedc, Deselliers, Kitsunegami, Excirial, Cry-walt, Moreau1, Sun Creator, Arjayay, SchreiberBike, The Yowser, XLinkBot, Jytdog, Gerhardvalentin, Avoided, Rreagan007, WikHead,Addbot, Mneuner, PetroleumAge, MrOllie, Download, CarsracBot, RTG, Favonian, Sindinero, Zorrobot, Jarble, Prawlings, Ben Ben,Legobot, Yobot, EdwardLane, Fraggle81, Librsh, AnomieBOT, DemocraticLuntz, Yukonpeegs, Archon 2488, Jim1138, Jo3sampl, Ckr-uschke, Citation bot, Quebec99, LilHelpa, Srich32977, GrouchoBot, Owenh000, SassoBot, Pikachu sensei, GESICC, Celuici, FrescoBot,Pnin2006, Blackguard SF, Shaibalahmar, Citation bot 1, Chenopodiaceous, Casprings, IrrtNie, Gautier lebon, Pinethicket, Bibliophile227,Jonesey95, Andynct, Rushbugled13, Jschnur, RedBot, CanberraBulldog, Elekhh, FoxBot, Trappist the monk, Jordgette, AHeneen, S1id3r0,Gregkaye, Dinamik-bot, Vrenator, Jeffrd10, Mean as custard, RjwilmsiBot, J36miles, EmausBot, John of Reading, Soporyc, Wikitanvir-Bot, Mabuzi, Jdkag, Laurabauer, GoingBatty, RA0808, Gimmetoo, Wikipelli, K6ka, ZéroBot, John Cline, Josve05a, Geperdo, Comp-dude123, Agent0060, Druzhnik, Xen1977, Ire2500, Rcsprinter123, Joshua Doubek, IGeMiNix, Rostz, Braculus, Donner60, Bulwersator,RockMagnetist, Sonicyouth86, ClueBot NG, Somedifferentstuff, Gilderien, Satellizer, Iloveandrea, Joefromrandb, Coastwise, Smm201`0,WebMaven2000, Snotbot, AdamRBrooks, Kevin Gorman, Law of Entropy, Rcorym15, Widr, Esnascosta, Helpful Pixie Bot, HMSSo-lent, Strike Eagle, Candleabracadabra, Wbm1058, Bibcode Bot, Denovoid, JohnEdit21, BG19bot, NewsAndEventsGuy, Yendor of yinn,Teach267, The Mark of the Beast, IlllIlIIOIlllIlII, Neøn, OpenMind, MusikAnimal, Frze, Amp71, Bonnie13J, Stephenwanjau, Mark Arsten,IraChesterfield, StephanieF79, Mis-misanthrope, Cameron6426a, Terrance.cunningham, Maxellus, EnviroE, Gorthian, Joydeep, T.hetton,Chase.alton3, KelseyBrook, FertileCatfish, OChemie, Carbon13neutral, Polmandc, Fracksand, Thegreatgrabber, Klilidiplomus, Hoppenhe,EnvPolKAL, Adamuwt2011, Proxyma, 17mansure, BrianWo, BattyBot, Easshale, EnergeticsAnalyst, DeRanged Resources, Emeritusedi-tor, Palpbert, Jfsparks, Brandiwessel, Nfaraguna, MissLoveIsMyWeapon, T.Dooshswag, Brentonchina, Sophk, The Illusive Man, TimothyGu, ChrisGualtieri, GrizBizzy, Roche398, Aldenallen1, Odewey, AJKeown, Kyle assassinz, Christine1223, EuroCarGT, Joseph.ruggiero,Illia Connell, Runtzz, Lhcollins, Zstallman, Writer1502, EagerToddler39, JurgenNL, SoledadKabocha, Mogism, Cerabot, Conor Strong,Fracmaster, Raiderredjd, Numbermaniac, Scgtcheck, Proper Stranger, Kleptopigstar, Newmanmu, Jpmsd, Mdicato, JustAMuggle, Elstree-230, Lgfcd, Gabby Merger, Whitepanthera, Exenola, Faizan, Sharmeka-winnsboro, Men404, PlanetEditor, Lbriggs, Tothesungod, Nog-ginquest, Jeffthajamaican, Jabx2, Wuerzele, Amanda.caggiano, CJ5Fanatic, Cjpepino, DavidLeighEllis, Nikolai778, Exesop, Luchi1223,Ellisnyc, ReconditeRodent, Alanis435, Firebrandcentral, Lil wayne666, GypsyEyes, 1822002hadrian, Hadrian0, Roman26, Mandruss, Mu-tantkarma, Caswivel, Noyster, Top5percent, Lpfleischmann, Sr75080, Chris.hooper78, Kikishiki, Patrivelaa, Maxluke, Batuhanguven94,G S Palmer, 7Sidz, Ur mumcxhbgvhjgvasdjk, Salubrious Toxin, Wiki at Royal Society John, Monkbot, Formerly 98, Leegrc, Doctor-Brominestein, Vieque, Cochandl77, Lwiklund, Paul SciencesPo, Kennywpara, Richard elwell, Savannahb022, Scarlettail, Sygac, Nikify,Hamzahno, Narddawg, Jr703569, El Kaput, Awesomeburner, Umkan, Njingo, Aimrux, Ckerr65, Richard Yin, Sourgosling, HIyer01, Don-nywinston, Griffindell, TFFX, Horses photos, Berg3usa, Rhod08, Fatetrevor, Pcook22, Antigomer, Tymon.r, Stoney1976, Turtle Guillotine,Thecrew1021, Xdspellmaster, Hvaara, Tjhlax, Mountainlove, 234 family, Catherath and Anonymous: 485

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