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<ref name="Neshaminy 2009">{{cite news|url=http://www.nbcphiladelphia.com/news/local/Pennsylvania-Allows-Fracking-Tainted-Water-Dumping-Gas-Drilling-112804034.html|title= 44,000 Barrels of Tainted Water Dumped Into Neshaminy Creek. We're the only state allowing tainted water into our rivers |publisher=NBC Philadelphia |agency=Associated Press |author=David Caruso |date=2011-01-03|accessdate=2012-04-28}}</ref>
<ref name="Neshaminy 2009">{{cite news|url=http://www.nbcphiladelphia.com/news/local/Pennsylvania-Allows-Fracking-Tainted-Water-Dumping-Gas-Drilling-112804034.html|title= 44,000 Barrels of Tainted Water Dumped Into Neshaminy Creek. We're the only state allowing tainted water into our rivers |publisher=NBC Philadelphia |agency=Associated Press |author=David Caruso |date=2011-01-03|accessdate=2012-04-28}}</ref>

<ref name="NYT lobbying docs">{{cite news |url=http://www.nytimes.com/interactive/2011/03/02/us/20110304-gas-documents3.html#document/p442/a10384 |title=The Debate Over the Hydrofracking Study's Scope |quote= While environmentalists have aggressively lobbied the agency to broaden the scope of the study, industry has lobbied the agency to narrow this focus |date=3 March 2011 |newspaper = The New York Times |accessdate=1 May 2012}}</ref>

<ref name="Urbina 03Mar2011">{{cite news |url=http://www.nytimes.com/2011/03/04/us/04gas.html |title=Pressure Limits Efforts to Police Drilling for Gas |first=Ian |last=Urbina |quote=More than a quarter-century of efforts by some lawmakers and regulators to force the federal government to police the industry better have been thwarted, as E.P.A. studies have been repeatedly narrowed in scope and important findings have been removed |date=3 March 2011 |newspaper=The New York Times |accessdate=23 February 2012}}</ref>

<ref name="Cornellvet03092012">{{cite news |url = http://www.news.cornell.edu/stories/March12/FrackingAnimals.html|title=Study suggests hydrofracking is killing farm animals, pets |author=Ramanuja, Krishna |date=7 Martch 2012 |newspaper = Cornell Chronicle |publisher=Cornell University|accessdate=9 March 2012}}</ref>

<ref name="Urbina 03Aug2011">{{cite news |url=http://www.nytimes.com/2011/08/04/us/04natgas.html |title=A Tainted Water Well, and Concern There May be More |first=Ian |last = Urbina |date=3 August 2011 |newspaper=The New York Times |accessdate=22 February 2012}}</ref>

<ref name="DammelNotes">{{Cite journal |url=http://mjlst.umn.edu/prod/groups/ahc/@pub/@ahc/@mjlst/documents/asset/ahc_asset_365154.pdf |last=Dammel |first=Joseph A. |year=2011 |title=Notes From Underground: Hydraulic Fracturing in the Marcellus Shale |journal=Minnesota Journal of Law, Science and Technology |volume=12 |issue=2 |publisher=[[University of Minnesota Law School]] |pages=773–810 |accessdate=24 February 2012|format = PDF}}</ref>

<ref name="EPA 2004">{{cite report |url=http://www.epa.gov/ogwdw/uic/pdfs/cbmstudy_attach_uic_final_fact_sheet.pdf |publisher=EPA |title=Evaluation of Impacts to Underground Sources of Drinking Water by Hydraulic Fracturing of Coalbed Methane Reservoirs; National Study Final Report |date=June 2004 |accessdate=23 February 2011|format = PDF}}</ref>

<ref name="No5635712">[http://ip.com/patent/US5635712] Scott III, George L. (03-June-1997) US Patent No. 5635712: Method for monitoring the hydraulic fracturing of a subterranean formation. US Patent Publications.</ref>

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

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


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Revision as of 00:50, 9 May 2012

"Fracking" redirects here. For the expletive, see Frak (expletive).
Hydraulic fracturing
Process typeMechanical
Industrial sector(s)Mining
Main technologies or sub-processesFluid pressure
Product(s)Natural gas
Petroleum
InventorHalliburton
Year of invention1947

Hydraulic fracturing is the propagation of fractures in a rock layer caused by the presence of a pressurized fluid. Some hydraulic fractures form naturally, as in the case of veins or dikes, and are a means by which gas and petroleum from source rocks may migrate to reservoir rocks. Induced hydraulic fracturing or hydrofracking, commonly known as fracking, is a technique used to release petroleum, natural gas (including shale gas, tight gas and coal seam gas), or other substances for extraction.[a][1] This type of fracturing creates fractures from a wellbore drilled into reservoir rock formations.

A distinction can be made between low-volume hydraulic fracturing used to stimulate high-permeability reservoirs, which may consume typically 20,000 to 80,000 US gallons (76,000 to 303,000 L; 17,000 to 67,000 imp gal) of fluid per well, with high-volume hydraulic fracturing, used in the completion of tight gas and shale gas wells; high-volume hydraulic fracturing can use as much as 2 to 3 million US gallons (7.6 to 11.4 Ml) of fluid per well.[2] This latter practice has come under scrutiny internationally, with some countries suspending or even banning it. The first frac job was performed in 1947, though the current fracking technique was first used in the late 1990s in the Barnett Shale in Texas.[1][3] The energy from the injection of a highly-pressurized fracking fluid creates new channels in the rock which can increase the extraction rates and ultimate recovery of fossil fuels.

According to the International Energy Agency, the global use of natural gas will rise by more than 50% compared to 2010 levels, and account for over 25% of world energy demand in 2035.[4] Proponents of fracking point to the vast amounts of formerly inaccessible hydrocarbons the process can extract. However, there remain large uncertainties in the amount of gas reserves that can be accessed in this way.[5] Detractors point to potential environmental impacts, including contamination of ground water, risks to air quality, the migration of gases and hydraulic fracturing chemicals to the surface, surface contamination from spills and flowback and the health effects of these.[6] State and federal regulatory agencies and the industry are working to address these concerns.[7] The EPA is conducting a study, set to be released for peer review at the end of 2012, of hydraulic fracturing's impact on drinking water and ground water resources.[8]

Schematic depiction of hydraulic fracturing for shale gas, showing potential environmental effects.

Mechanics

Fracturing in rocks at depth is suppressed by the confining pressure, due to the load caused by the overlying rock strata. This is particularly so in the case of 'tensile' (Mode 1) fractures, which require the walls of the fracture to move apart, working against this confining pressure. Hydraulic fracturing occurs when the effective stress is reduced sufficiently by an increase in the pressure of fluids within the rock, such that the minimum principal stress becomes tensile and exceeds the tensile strength of the material.[9][10] Fractures formed in this way will typically be oriented perpendicularly to the minimum principal stress and for this reason, induced hydraulic fractures in wellbores are sometimes used to determine stress orientations.[11] In natural examples, such as dikes or vein-filled fractures, their orientations can be used to infer past stress states.[12]

Natural examples

Rocks often contain evidence of past hydraulic fracturing events.

Veins

Most vein systems are a result of repeated hydraulic fracturing during periods of relatively high pore fluid pressure. This is particularly clear in the case of 'crack-seal' veins, where the vein material can be seen to have been added in a series of discrete fracturing events, with extra vein material deposited on each occasion.[13] One mechanism to explain such examples of long-lasting repeated fracturing is the effects of seismic activity, in which the stress levels rise and fall episodically and large volumes of fluid may be expelled from fluid-filled fractures during earthquakes. This process is referred to as 'seismic pumping'.[14]

Dikes

High-level minor intrusions such as dikes propagate through the crust in the form of fluid-filled cracks, although in this case the fluid is magma. In sedimentary rocks with a significant water content the fluid at the propagating fracture tip will be steam.[15]

Induced hydraulic fracturing

The technique of hydraulic fracturing is used to increase or restore the rate at which fluids, such as petroleum, water, or natural gas can be produced 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 production of natural gas and oil from rock formations deep below the earth's surface (generally 5,000–20,000 feet (1,500–6,100 m)). At such depth, there may not be sufficient permeability or reservoir pressure to allow natural gas and oil to flow from the rock into the wellbore at economic rates. Thus, creating conductive fractures in the rock is essential to extract gas from shale reservoirs because of the extremely low natural permeability of shale, which is measured in the microdarcy to nanodarcy range.[16] Fractures provide a conductive path connecting a larger area of the reservoir to the well, thereby increasing the area from which natural gas and liquids can be recovered from the targeted formation. So-called 'super fracking', which creates cracks deeper in the rock formation to release more oil and gas, will allow companies to frack more efficiently.[17] The yield for a typical shale gas well generally falls off sharply after the first year or two.[18]

While the main industrial use of hydraulic fracturing is in stimulating production from oil and gas wells,[19][20][21] hydraulic fracturing is also applied to:

  • Stimulating groundwater wells[22]
  • Preconditioning rock for caving or inducing rock to cave in mining[23]
  • As a means of enhancing waste remediation processes, usually hydrocarbon waste or spills[24]
  • Dispose of waste by injection into deep rock formations
  • As a method to measure the stress in the earth
  • For heat extraction to produce electricity in an enhanced geothermal systems.[25]

History

The first hydraulic fracturing was performed in 1947, at the Hugoton gas fields of southwestern Kansas, in limestone deposits by Halliburton.[1] Since then, hydraulic fracturing has been used to stimulate approximately a million oil and gas wells.[26] Significant R&D and technology demonstration were necessary before hydraulic fracturing could be commercially applied to shale gas deposits, due to shale's high porosity and low permeability. In the 1970s the federal government initiated both the Eastern Gas Shales Project, a set of dozens of public-private hydro-fracturing pilot demonstration projects, and the Gas Research Institute, a gas industry research consortium that received approval for research and funding from the Federal Energy Regulatory Commission.[27] Over this time, Sandia National Laboratories was conducting research into microseismic imaging for use in coalbeds, a geologic mapping technique that would prove crucial for the commercial recovery of natural gas from shale as well as oil from offshore drilling rigs. In the late 1970s, the Department of Energy pioneered massive hydraulic fracturing, a completion technique that would be improved upon for the economic recovery of shale gas in the future.

In 1980s improvements of existing and implementation of new technologies for horizontal drilling increased its application in conventional drilling. Among others these improvements included usage of downhole drilling motors and telemetry equipment.[26] In 1986, a joint DOE-private venture completed the first successful multi-fracture horizontal well in shale. The Department of Energy later subsidized Mitchell Energy's first successful horizontal drill in the north-Texas Barnett Shale in 1991.[28] Mitchell Energy engineers would go on to develop the hydraulic fracturing technique known as 'slickwater fracturing' that started the modern shale gas boom.[29]

Method

A hydraulic fracture is formed by pumping the fracturing fluid into the wellbore at a rate sufficient to increase pressure downhole to exceed that of the fracture gradient of the rock.[30] The rock cracks and the fracture fluid continues farther into the rock, extending the crack still farther, and so on. 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 particulates, that prevent the fractures from closing when the injection is stopped. Consideration of proppant strengths and prevention of proppant failure becomes more important at deeper depths where pressure and stresses on fractures are higher. The propped fracture is permeable enough to allow the flow of formation fluids to the well. Formation fluids include gas, oil, salt water, fresh water and fluids introduced to the formation during completion of the well during fracturing.[30]

The location of one or more fractures along the length of the borehole is strictly controlled by various different methods which create or seal-off holes in the side of the wellbore. Typically, hydraulic fracturing is performed in cased wellbores and the zones to be fractured are accessed by perforating the casing at those locations.[31]

Well types

While hydraulic fracturing is many times performed in vertical wells, today it is also performed in horizontal wells. When done in already highly-permeable reservoirs such as sandstone-based wells, the technique is known as "well stimulation".

Horizontal drilling involves wellbores where the terminal drillhole is 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 also reduces surface disruptions as fewer wells are required. Drilling usually induces damage to the pore space at the wellbore wall, reducing the 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. Hydraulic fracturing can be used to restore permeability.[citation needed]

Hydraulic fracturing is commonly applied to wells drilled in low permeability reservoir rock.

Fracturing

The fluid injected into the rock is typically a slurry of water, proppants, and chemical additives. Additionally, gels, foams, and compressed gases, including nitrogen, carbon dioxide and air can be injected. According to Kathleen Hartnett White of the Armstrong Center for Energy & the Environment, of the fracking fluid over 99.5% is water and sand, and the chemicals accounts about 0.5%.[32] According to the study prepared for the United States DEpartment of Energy, the additives in the fracturing fluid accounts 0.5–2% while water accounts 98–99.5%.[30]

There are more than 50 types of fluids that can potentially be used as fracturing fluids, following are the fracturing fluids used at more than 95% of Fracturing jobs world wide:

  • Conventional linear gels. These gels are Cellulose derivatives (CMC,HEC,CMHEC, HPCMHEC), Guar or its derivatives (HPG,CMHPG) based, with other chemicals providing the necessary chemistry for the desired results.
  • 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 proppants. 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 is therefore pumped out.
  • Organometallic-crosslinked fluids Zirconium, Chromium, Antimony, Titanium Salts are known to cross-link the guar based gels. The cross-linking mechanism is not reversible. So once the proppant is pumped down along with the cross-linked gel and the fracturing part is done. The gels are broken down with appropriate breakers.[2]
  • Aluminium phosphate-ester oil gels. Aluminium phosphate and ester oils are slurried to form cross-linked gel. These are one of first known gelling systems. They are very limited in use currently, because of formation damage and the difficulty in clean-up.

Water is by far the largest component of fracking fluids. The initial drilling operation itself may consume from 6,000 to 600,000 US gallons (23,000 to 2,271,000 L; 5,000 to 499,600 imp gal) of fracking fluids. Over its lifetime an average well will require up to an additional 5 million US gallons (19 Ml) of water for the initial hydraulic fracturing operation and possible restimulation frac jobs.[33] The large volumes of water required have raised concerns about fracking in arid areas, such as Karoo in South Africa.[34]

Various types of proppant include silica sand, resin-coated sand, and man-made ceramics. These vary depending on the type of permeability or grain strength needed. The most commonly utilized proppant is silica sand. However, proppants of uniform size and shape, such as a ceramin proppant, is believed to be more effective. Due to a higher porosity within the fracture, a greater amount of oil and natural gas is liberated.[35] Sand containing naturally radioactive minerals is sometimes used so that the fracture trace along the wellbore can be measured. Chemical additives are applied to tailor the injected material to the specific geological situation, protect the well, and improve its operation, varying slightly based on the type of well. The composition of injected fluid is sometimes changed as the fracturing job proceeds. Often, acid is initially used to scour the perforations and clean up the near-wellbore area. Afterward, high pressure fracture fluid is injected into the wellbore, with the pressure above the fracture gradient of the rock. This fracture fluid contains water-soluble gelling agents (such as guar gum) which increase viscosity and efficiently deliver the proppant into the formation.[2] As the fracturing process proceeds, viscosity reducing agents such as oxidizers and enzyme breakers are sometimes then added to the fracturing fluid to deactivate the gelling agents and encourage flowback.[2] The proppant's purpose is primarily to provide a permeable and permanent filler to fill the void created during the fracturing process. At the end of the job the well is commonly flushed with water (sometimes blended with a friction reducing chemical) under pressure. Injected fluid is to some degree recovered and is managed by several methods, such as underground injection control, treatment and discharge, recycling, or temporary storage in pits or containers while new technology is being developed to better handle wastewater and improve reusability.[30] Although the concentrations of the chemical additives are very low, the recovered fluid may be harmful due in part to hydrocarbons picked up from the formation.

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 quintiplex pumps) and a monitoring unit. Associated equipment includes fracturing tanks, one or more units for storage and handling of proppant, high pressure treating iron, 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. 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).[citation needed]

Fracture monitoring

Injection of radioactive tracers along with the other substances in hydraulic fracturing fluid is used to determine the injection profile and location of fractures created by hydraulic fracturing.[36] Patents[37][38][39] and the US Nuclear Regulatory Commission list a wide range or radioactive materials in solid, liquid and gaseous forms that are used as field flood or enhanced oil and gas recovery study applications tracers used in single and multiple wells. Some of the most commonly used appear to be Antimony-124, Bromine-82, Iodine-131, Iodine-125, Iridium-192, and Scandium-46. Amounts per injection of radionuclide are also listed.[40]

Measurements of the pressure and rate during the growth of a hydraulic fracture, as well as knowing the properties of the fluid 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.[30]

For more advanced applications, Microseismic monitoring is sometimes used to estimate the size and orientation of hydraulically 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 hydraulic fracture, the approximate geometry of the fracture is inferred. Tiltmeter arrays, deployed on the surface or down a well, provide another technology for monitoring the strains produced by hydraulic fracturing.[citation needed]

Horizontal completions

Since the early 2000s, advances in drilling and completion technology have made drilling horizontal wellbores much more economical. Horizontal wellbores allow for far greater exposure to a formation than a conventional vertical wellbore. 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 many times, especially in North America. The type of wellbore completion used will affect how many times the formation is fractured, and at what locations along the horizontal section of the wellbore.[41]

In North America, shale reservoirs such as the Bakken, Barnett, Montney, Haynesville, Marcellus, and most recently the Eagle Ford, Niobrara adn Utica shales are drilled, completed and fractured using this method. 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'. [citation needed]

The wellbore for a plug and perf job is generally composed of standard joints of steel casing, either cemented or uncemented, which is set in place at the conclusion of the drilling process. Once the drilling rig has been removed, a wireline truck is used to perforate near the end of the well, following which a fracturing job is pumped (commonly called a stage). Once the stage is finished, the wireline truck will set a plug in the well to temporarily seal off that section, and then perforate the next section of the wellbore. Another stage is then pumped, and the process is repeated as necessary along the entire length of the horizontal part of the wellbore.[42]

The wellbore for the sliding sleeve 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 ready to be fractured, using one of several activation techniques, the bottom sliding sleeve is opened and the first stage gets pumped. Once finished, the next sleeve is opened which concurrently isolates the first stage, and the process repeats. For the sliding sleeve method, wireline is usually not required.[citation needed]

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.[7]

Chemicals

Over the life of a typical well, this may amount to 100,000 US gallons (380,000 L; 83,000 imp gal) of chemical additives. These additives (listed in a U.S. House of Representatives Report[43]) include biocides, surfactants, viscosity-modifiers, and emulsifiers. They vary widely in toxicity: Many are used in household products such as cosmetics, lotions, soaps, detergents, furniture polishes, floor waxes, and paints,[44] and some are used in food products. Some, however, are known carcinogens, some are toxic, and some are neurotoxins. For example: benzene (causes cancer, bone marrow failure), lead (damages the nervous system and causes brain disorders), ethylene glycol (antifreeze, causes death), methanol (highly toxic), boric acid (kidney damage, death), 2-butoxyethanol (causes hemolysis).

Injection of radioactive tracers along with the other substances in hydraulic fracturing fluid is used to determine the injection profile and location of fractures created by hydraulic fracturing.[40] A large number of gamma-emitting isotopes deemed appropriate for this use are named in patents.[40][38] These patents also describe how several tracers are typically combined and injected together.[37][39] Their half lives range from 40.2 hours (Lanthanum-140) to 5.27 years (Cobalt-60).[45]

The 2011 US House of Representatives investigative report on the chemicals used in hydraulic fracturing states that out of 2,500 hydraulic fracturing products, "[m]ore than 650 of these products contained chemicals that are known or possible human carcinogens, regulated under the Safe Drinking Water Act, or listed as hazardous air pollutants".[43] The report also shows that between 2005 and 2009, 279 products had at least one component listed as "proprietary" or "trade secret" on their Occupational Safety and Health Administration (OSHA) required Material Safety Data Sheet (MSDS). The MSDS is a list of chemical components in the products of chemical manufacturers, and according to OSHA, a manufacturer may withhold information designated as "proprietary" from this sheet. When asked to reveal the proprietary components, most companies participating in the investigation were unable to do so, leading the committee to surmise these “companies are injecting fluids containing unknown chemicals about which they may have limited understanding of the potential risks posed to human health and the environment” (12).[43] Without knowing the identity of the proprietary components, regulators cannot test for their presence. This prevents government regulators from establishing baseline levels of the substances prior to hydraulic fracturing and documenting changes in these levels, thereby making it impossible to prove that hydraulic fracturing is contaminating the environment with these substances.[46] Third-party laboratories are performing analyses on soil, air, and water near the fracturing sites to measure the level of contamination by some of the known chemicals, but not the proprietary substances, involved in hydraulic fracturing. Each state has a contact person in charge of such regulation.[47] A map of these contact people can be found at FracFocus.org as well.[48]

Another 2011 study identified 632 chemicals used in natural gas operations. Only 353 of these are well-described in the scientific literature; and of these, more than 75% could affect skin, eyes, respiratory and gastrointestinal systems; roughly 40-50% could affect the brain and nervous, immune and cardiovascular systems and the kidneys; 37% could affect the endocrine system; and 25% were carcinogens and mutagens. The study indicated possible long-term health effects that might not appear immediately. The study recommended full disclosure of all products used, along with extensive air and water monitoring near natural gas operations; it also recommended that fracking's exemption from regulation under the US Safe Drinking Water Act be rescinded.[49]

Some states have started requiring natural gas companies to "disclose the names of all chemicals to be stored and used a drilling site," keeping a record on file at the state’s environmental agency, such as the case in Pennsylvania with the Department of Environmental Protection and in New York with the Department of Environmental Conservation.[50] However, the continuing concern of some activists who oppose hydraulic fracturing is the lack of information really provided. According to Weston Wilson in Affirming Gasland, "about 50% or so of these MSDS sheets lack a specific chemical name, and some MSDS sheets simply claim 'proprietary' status and list none of the chemicals in that container."[51] As a result, some activists are calling for specific disclosure of chemicals used, such as the Chemical Abstract Service (CAS) number and specific chemical formulas, and increased access to such information. In his State of the Union address for 2012, Barack Obama stated his intention to force fracking companies to disclose the chemicals they use,[52] though the subsequent, proposed guidelines were criticised for failing to specify how drillers will disclose the chemicals they use.[53]

Terminology

Fracture gradient
The pressure to fracture the formation at a particular depth divided by the depth. A fracture gradient of 18 kPa/m (0.8 psi/foot) implies that at a depth of 3 km (10,000 feet) a pressure of 54 MPa (8,000 psi) will extend a hydraulic fracture.
ISIP — Initial shut in pressure
The pressure measured immediately after injection stops. The ISIP provides a measure of the pressure in the fracture at the wellbore by removing contributions from fluid friction.
Leakoff
Loss of fracturing fluid from the fracture channel into the surrounding permeable rock.
Fracturing fluid
The fluid used during a hydraulic fracture treatment of oil, gas, or water wells. The fracturing fluid has three major functions:
  1. Open and extend the fracture.
  2. Transport the proppant along the fracture length.
  3. Transport radioactive tracers through the fractures to determine the injection profile and track the locations of fractures.[36][38][37][39]
Proppant
Suspended particles in the fracturing fluid that are used to hold fractures open after a hydraulic fracturing treatment, thus producing a conductive pathway that fluids can easily flow along. Naturally occurring sand grains or artificial ceramic material are common proppants used.

Environmental concerns

Main article: Environmental impact of hydraulic fracturing
See also: Environmental impact of hydraulic fracturing in the United States

Environmental concerns with hydraulic fracturing include the potential contamination of ground water, risks to air quality, the potential migration of gases and hydraulic fracturing chemicals to the surface, the potential mishandling of waste, and the health effects of these, like cancer.[6][43] Many cases of suspected groundwater contamination have been documented.[54][55] The EPA has noted that "Ground water contamination with constituents such as those found at Pavillion is typically infeasible or too expensive to remediate or restore (GAO 1989)."[56] Because hydraulic fracturing was invented in the United States[34] and therefore has a longer history there, most of the studies of the environmental impact have been conducted there.

Challenges to research

Industry and governmental pressure have made it difficult to conduct and report the results of comprehensive studies of hydraulic fracturing. The New York Times has reported that, "While environmentalists have aggressively lobbied the agency to broaden the scope of the study, industry has lobbied the agency to narrow this focus."[57] It also reported EPA investigations into the oil and gas industry's environmental impact have been narrowed in scope and/or had negative findings removed due to industry and government pressure,[57][58] although the EPA has stood by their statements.[citation needed] A 2012 Cornell University report noted that it was difficult to assess health impact because of legislation, proprietary secrecy, and non-disclosure agreements that allow them to keep the proprietary chemicals used in the fluid secret. Cornell researcher Bamberger stated that if you don't know what chemicals are, you can't conduct pre-drilling tests and establish a baseline to prove that chemicals found postdrilling are from hydraulic fracturing.[59] The researchers recommended requiring disclosure of all hydraulic fracturing fluids, that nondisclosure agreements not be allowed when public health is at risk, testing animals raised near hydraulic fracturing sites and animal products (milk, cheese, etc.) from animal raised near hydraulic fracturing sites prior to selling them to market, monitoring of water, soil and air more closely, and testing the air, water, soil and animals prior to drilling and at regular intervals thereafter.[59] In addition, after court cases concerning contamination from hydraulic fracturing are settled, the documents are sealed. While the American Petroleum Institute deny that this practice has hidden problems with gas drilling, others believe it has and could lead to unnecessary risks to public safety and health.[60]

New York State Assembly members Robert Castelli and Steve Katz call for a moratorium on hydraulic fracturing in the Croton Watershed in October 2010.

The New York Times also reported that the results of the 2004 EPA Study were censored due to strong industry influence and political pressure (regulatory capture).[58] An early draft of the study discussed the possibility of dangerous levels of fracking fluid contamination, and mentioned "possible evidence" of aquifer contamination. The final report concluded simply that fracking "poses little or no threat to drinking water".[58] The study's scope was narrowed so that it only focused on the injection of fracking fluids, ignoring other aspects of the process such as disposal of fluids, and environmental concerns such as water quality, fish kills and acid burns. The study was concluded before public complaints of contamination started emerging.[61]: 780  The study's conclusion that the injection of fracking fluids into coalbed methane wells posed a minimal threat to underground drinking water sources[62] may have influenced the 2005 Congressional decision to exempt hydraulic fracturing from regulation under the Safe Drinking Water Act.

The 2012 EPA Hydraulic Fracturing Draft Plan was also narrowed.[57] It does not include studying the effects of iodine-131 or other radioactive tracer isotopes used in hydraulic fracturing,[38][37][39][5] but may use other tracers to verify sources of contamination.[57] The draft plan also omits the evaluation of the impact of wastewater. Christopher Portier, director of the US CDC's National Center for Environmental Health and the Agency for Toxic Substances and Disease Registry, argued that, in addition to the EPA's plans to investigate the impact of fracking on drinking water, additional studies should be carried out to determine whether wastewater from the wells can harm people or animals and vegetables they eat.[63] A group of US doctors called for a moratorium on fracking in populated areas until such studies had been done.[17][64]

Air emissions

The main hydraulic-fracturing-related air emissions are methane emissions from the wells during fracturing and emissions from hydraulic fracturing equipment, such as compressor stations. According to the study conducted by professor Robert W. Howarth et al. of Cornell University, "3.6% to 7.9% of the methane from shale-gas production escapes to the atmosphere in venting and leaks over the lifetime of a well." According to the study, this is at least 30% and perhaps even 100% more than from conventional gas production. The study explains these higher emissions with hydraulic fracturing and drill out following the fracturing.[65] Methane gradually breaks down in the atmosphere, forming carbon dioxide. It means its greenhouse-gas footprint is worse than coal or oil for timescales of less than fifty years.[65][66] However, several studies have argued that the paper was flawed and/or come to completely different conclusions, including assessments by experts at the US Department of Energy,[67] by Carnegie Mellon University[68] and the University of Maryland,[69] as well as by the Natural Resources Defense Council, which concluded that the Howarth et al. paper's use of a 20-year time horizon for global warming potential of methane is "too short a period to be appropriate for policy analysis."[70] In January 2012, Howarth's colleagues at Cornell University responded with their assessment, arguing that the Howarth paper was "seriously flawed" because it "significantly overestimate[s] the fugitive emissions associated with unconventional gas extraction, undervalue[s] the contribution of 'green technologies' to reducing those emissions to a level approaching that of conventional gas, base[s] their comparison between gas and coal on heat rather than electricity generation (almost the sole use of coal), and assume[s] a time interval over which to compute the relative climate impact of gas compared to coal that does not capture the contrast between the long residence time of CO2 and the short residence time of methane in the atmosphere."[71] The authors of that response conclude that "shale gas has a GHG footprint that is half and perhaps a third that of coal," based upon "more reasonable leakage rates and bases of comparison." Howarth et al. responded to this criticism: "We stand by our approach and findings. The latest EPA estimate for methane emissions from shale gas falls within the range of our estimates but not those of Cathles et al, which are substantially lower."[72][73]

In 2008, measured ambient concentrations near drilling sites in Sublette County, Wyoming were frequently above the National Ambient Air Quality Standards (NAAQS) of 75ppb and have been recorded as high as 125 ppb.[74] A 2011 study for the city of Fort Worth, Texas, examining air quality around natural gas sites "did not reveal any significant health threats."[75][76] In DISH, Texas, elevated levels of disulphides, benzene, xylenes and naphthalene have been detected in the air, emitted from the compressor stations.[77] People living near shale gas drilling sites often "complain of headaches, diarrhea, nosebleeds, dizziness, blackouts, muscle spasms, and other problems."[78] Cause-and-effect relationships have not been established.[78] In Garfield County, Colorado, another area with a high concentration of drilling rigs, volatile organic compound emissions increased 30% between 2004 and 2006; during the same period there was a rash of health complaints from local residents. Epidemiological studies that might confirm or rule out any connection between these complaints and fracking are virtually non-existent.[6] In 2012, researchers from the Colorado School of Public Health showed that air pollution caused by fracking may contribute to "acute and chronic health problems" for those living near drilling sites.[79]

Groundwater contamination

There are documented incidents of contamination. As early as 1987, an E.P.A. report was published that indicated fracture fluid invasion into James Parson's water well in Jackson County, West Virginia. The well, drilled by Kaiser Exploration and Mining Company, was found to have induced fractures that created a pathway to allow fracture fluid to contaminate the groundwater from which Mr. Parson's well was producing. The oil and gas industry and the E.P.A. disagreed regarding the accuracy and thoroughness of this report.[60] In 2006 over 7 million cubic feet (200×10^3 m3) of methane were released from a blown gas well in Clark, Wyoming and shallow groundwater was found to be contaminated.[80] Directed by Congress, the U.S. EPA announced in March 2010 that it will examine claims of water pollution related to hydraulic fracturing.[81]

In 2009 13 water wells Dimock, Pennsylvania were contaminated with methane (one blew up). Cabot Oil & Gas had to financially compensate residents and construct a pipeline to bring in clean water. The company continues to deny that any "of the issues in Dimock have anything to do with hydraulic fracturing".[61][82][83][84] The devices needed to prevent such water contamination cost as little as $600.[85] Confusion remains regarding whether the water in Dimock is safe to drink.[86]

In 2010 the film Gasland premiered at the Sundance Film Festival. The filmmaker claims that chemicals including toxins, known carcinogens, and heavy metals polluted the ground water near well sites in Pennsylvania, Wyoming, and Colorado.[87] The film was criticized by oil and gas industry group[88] Energy in Depth as factually inaccurate;[50] in response, a detailed rebuttal of the claims of inaccuracy has been posted on Gasland's website.[89]

Complaints about water quality from residents near a gas field in Pavillion, Wyoming prompted an EPA groundwater investigation. The EPA reported detections of methane and other chemicals such as phthalates in private water wells.[56] An EPA draft report dated December 8, 2011 suggested that the ground water in the Pavillion, Wyoming, aquifer contains "compounds likely associated with gas production practices, including hydraulic fracturing".[90][91][92] The EPA discovered traces of methane and foaming agents in several water wells near a gas rig. Samples of water taken from EPA’s deep monitoring wells in the aquifer were found to contain gasoline, diesel fuel, BTEX (benzene, toluene, ethylbenzene, xylene), naphthalenes, isopropanol, and synthetic chemicals (e.g., glycols and alcohols) used in gas production and hydraulic fracturing fluid, and high methane levels. Benzene concentrations in the samples were well above Safe Drinking Water Act standards.[90] The EPA report stated concerns about the movement of contaminants within the aquifer and the future safety of drinking water in the context of the area’s complex geology. EPA's sampling of Pavillion area drinking water wells found chemicals consistent with those reported in previous EPA reports, including but not limited to methane and other petroleum hydrocarbons, indicating migration of contaminants from areas of gas production.[90] The report also said that contaminants in wells near pits indicated that (frack) pits are a source of shallow ground water contamination. It also said, "Detections of organic chemicals are more numerous and exhibit higher concentrations in the deeper of the two monitoring wells … (which) along with trends in methane, potassium, chloride, and pH, suggest a deep source of contamination." Their observations of chemical reactions in the field led them to suggest that upward migration of chemicals from deep underground is the culprit. They also found that the reports companies filed detailing jobs listed chemicals as a class or as "proprietary," "rendering identification of constituents impossible."[93] The draft report also stated: "Alter­na­tive expla­na­tions were care­fully con­sid­ered to explain indi­vid­ual sets of data. How­ever, when con­sid­ered together with other lines of evi­dence, the data indi­cates likely impact to ground water that can be explained by hydraulic fracturing."[94] The EPA also said that the type of contamination found is "typically infeasible or too expensive to remediate or restore."[56]

It is important to note that not every instance of groundwater methane contamination is a result of hydraulic fracturing. Often, local water wells drill through many shale and coal layers that can naturally seep methane into the producing groundwater. This methane is often biogenic (created by organic material decomposition) in origin as opposed to thermogenic (created through "thermal decomposition of buried organic material"[95]). Thermogenic methane is the methane most often sought after by oil & gas companies deep in the earth, whereas biogenic methane is found in shallower formations (where water wells are typically drilled). Through isotope analysis and other detection methods, it is often fairly easy to determine whether the methane is biogenic or thermogenic, and thus determine from where it is produced.[95] The presence of thermogenic methane does not confirm the source of gas. The gas composition and isotopic finger print must compared by experts with other known sources of gas to confirm a match.[96]

Several 2011 studies also suggested contamination. Investigators from the Colorado School of Public Health conducted a study in Garfield and concluded that residents near gas wells might suffer chemical exposures, accidents from industry operations, and psychological impacts such as depression, anxiety and stress. This study (the only one of its kind to date) was never published, owing to disagreements between community members and the drilling company over the study's methods.[78] Additionally, the Colorado Oil & Gas Conservation Commission has found some wells containing thermogenic methane due to oil and gas development upon investigating complaints from residents.[97] A Duke University study published in Proceedings of the National Academy of Sciences examined methane in groundwater in Pennsylvania and New York states overlying the Marcellus Shale and the Utica Shale. It determined that groundwater tended to contain much higher concentrations of methane near fracking wells, with potential explosion hazard; the methane's isotopic signatures and other geochemical indicators were consistent with it originating in the fracked deep shale formations, rather than any other source.[98] A 2011 report by the Massachusetts Institute of Technology addressed groundwater contamination, noting "There has been concern that these fractures can also penetrate shallow freshwater zones and contaminate them with fracturing fluid, but there is no evidence that this is occurring. There is, however, evidence of natural gas migration into freshwater zones in some areas, most likely as a result of substandard well completion practices by a few operators. There are additional environmental challenges in the area of water management, particularly the effective disposal of fracture fluids". This study encourages the use of industry best practices to prevent such events from recurring.[99]

A University of Texas study described the environmental impact of each part of the hydraulic fracturing process[26] These parts include of (1) drill pad construction and operation, (2) the construction, integrity, and performance of the wellbores, (3) the injection of the fluid once it is underground (which proponents consider the actual "fracking"), (4) the flowback of the fluid back towards the surface, (5) blowouts, often unreported, which spew hydraulic fracturing fluid and other byproducts across surrounding area, (5) integrity of other pipelines involved and (6) the disposal of the flowback, including waste water and other waste products.[100][101] All but the injection stage were reported to be sources of contamination.[26] The UT study listed groundwater contamination, blowouts and house explosions, water consumption and supply, spill management, atmospheric emissions, and health effects as problems associated with hydraulic fracturing[26] The study concluded that if hydraulic fracturing is to be conducted in an environmentally safe manner, these issues need to be addressed first.[26] Proponents have reported that groundwater contamination results from all other parts of the hydraulic fracturing process but the "fracking" (the injection of hydraulic fracturing chemicals into Shale rock formations). Injection cannot be accomplished, however, without the accompanying stages. Poorly constructed or damaged wellbores and pipelines can allow the fluid to flow into aquifers.[26] Volatile chemicals held in waste water evaporation ponds can to evaporate or overflow and end up in groundwater systems. Trucks carrying fracking chemicals and wastewater can spill them during accidents. Disposal of fracking fluid by injection can cause earthquakes. Disposal of unprocessed or under-processed waste water into rivers can contaminate water supplies.[26] Critics have noted that it is "difficult for researchers to be objective if their university receives a lot of grants and funds from the industry.”[102] A UT Energy Institute spokesperson said that the study was not funded by the industry. He said funds came from the university, which has a variety of funding sources.[102] Statoil announced a $5m research agreement with UT's Bureau of Economic Geology in September 2011, whose program director, Ian Duncan, was the senior contributor for the parts of the Texas study to do with the environmental impacts of shale gas development.[26][103][104] The leader of the Texas study, Charles "Chip" Groat, is a paid director of PXP, an oil and gas company that is engaged in fracking, has acknowledged that a forthcoming report by the EPA will negate his study's findings that there are no adverse environmental consequences unique to fracking.[105]

Concerns over possible radioactive contamination in the United States

Main article: Environmental impact of hydraulic fracturing in the United States § Radioactive contamination

Radioactive wastewater contamination has been of particular concern in Pennsylvania. In Pennsylvania, much of the wastewater from hydraulic fracturing operations is processed by public sewage treatment plants.[106] Treatment plants are still not equipped to remove radioactive material and are not required to test for it.[107] The New York Times has reported radiation in wastewater from natural gas wells, which releases into Pennsylvania rivers,[107] and compiled a map of contamination levels,[108] along with stating that some United States Environmental Protection Agency reports were never made public. The Times' reporting on the issue has come under some criticism, though.[109][110][111] Due to these concerns the EPA has asked the Pennsylvania Department of Environmental Protection to require community water systems in certain locations, and centralized wastewater treatment facilities to conduct testing for radionuclides. Safe drinking water standards have not yet been set for many of the substances known to be in hydraulic fracturing fluids or their radioactivity levels,[107] and although water suppliers are required to inform citizens, through their annual drinking water reports, of the level of radon and other radionuclides in their water,[112] this doesn't always happen.[113]

Earthquakes

A report in the UK concluded that fracking was the likely cause of some small earth tremors that happened during shale gas drilling.[114][115][116] In addition, the United States Geological Survey (USGS) reports that, "Earthquakes induced by human activity have been documented in a few locations" in the United States, Japan, and Canada, "the cause [of which] was injection of fluids into deep wells for waste disposal and secondary recovery of oil, and the use of reservoirs for water supplies."[117] The disposal and injection wells referenced are regulated under the Safe Drinking Water Act and UIC laws and are not wells where hydraulic fracturing is generally performed.[citation needed]

Several earthquakes—including a light, magnitude 4.0 one on New Year's Eve—that had hit Youngstown, Ohio, throughout 2011 are likely linked to a disposal well for injecting wastewater used in the hydraulic fracturing process, according to seismologists at Columbia University.[118] Consequently, Ohio has since tightened its rules regarding the wells,[119] increased fees, and is considering a moratorium on the practice.[119]

Public policy and public relations

Governments are developing legislation related to hydraulic fracturing. The US has the longest history with hydraulic fracturing, so its approaches to hydraulic fracturing may be modeled by other countries.[34] In the US, some states have introduced legislation that limits the ability of municipalities to use zoning to protect citizens from exposure to pollutants from hydraulic fracturing by protecting residential areas. For instance, In Pennsylvania, The new Marcellus Shale Law (House Bill 1950)[120] requires all municipalities to allow Marcellus Shale well drilling in all zoning districts, including residential, and allow water and wastewater pits in all zoning district, including residential. Compressor stations must be allowed in industrial and agricultural zoning districts, and gas processing plants allowed in industrial zoning districts. Municipalities are no longer permitted to limit the hours of operation of gas related activities. Gas pipelines must be allowed in all zoning districts.[120] Similar laws have been created in Ohio,[121] and New York, Colorado, and Texas are battling over related legislation.[122] The Marcellus Shale Law (House Bill 1950) also contains a provision that allows doctors in Pennsylvania access to the list of chemicals in hydraulic fracturing fluid in emergency situations only, and forbids them from ever discussing this information with their patients.[123]

The considerable opposition against fracking activities in local townships has led companies to adopt a variety of public relations measures to assuage fears about fracking, including the admitted use of "mil­i­tary tac­tics to counter drilling oppo­nents". At a conference where public relations measures were discussed, a senior executive at Anadarko Petroleum was recorded on tape saying, "Download the US Army / Marine Corps Counterinsurgency Manual, because we are dealing with an insurgency", while referring to fracking opponents. Matt Pitzarella, spokesman for the most important fracking company in Pennsylvania, Range Resources, also told other conference attendees that Range employed psychological warfare operations veterans. According to Pitzarella, the experience learned in the Middle East has been valuable to Range Resources in Pennsylvania, when dealing with emotionally-charged township meetings and advising townships on zoning and local ordinances dealing with fracking.[124][125]

See also

Notes

a. ^ Also spelled "fraccing"[126] or "fracing".[127][128]

References

  1. ^ a b c Charlez, Philippe A. (1997). Rock Mechanics: Petroleum Applications. Paris: Editions Technip. p. 239.
  2. ^ a b c d Anthony Andrews; et al. (30 October 2009). Unconventional Gas Shales: Development, Technology, and Policy Issues (PDF). Congressional Research Service. p. ?. Retrieved 22 February 2012. {{cite book}}: Explicit use of et al. in: |author= (help)
  3. ^ McKibben, Bill (8 March 2012). "Why Not Frack?". The New York Review of Books. Retrieved 21 February 2012.
  4. ^ World Energy Outlook 2011: Are We Entering a Golden Age of Gas? (PDF) (Report). International Energy Agency. 9 November 2011. pp. ?. Retrieved 3 March 2012. Based on the assumptions of the GAS Scenario, from 2010 gas use will rise by more than 50% and account for over 25% of world energy demand in 2035—surely a prospect to designate the Golden Age of Gas.
  5. ^ Urbina, Ian (28 January 2012). "New Report by Agency Lowers Estimates of Natural Gas in U.S." The New York Times. Retrieved 23 February 2012.
  6. ^ a b c Brown, Valerie J. (February 2007). "Industry Issues: Putting the Heat on Gas". Environmental Health Perspectives. 115 (2). US National Institute of Environmental Health Sciences: A76. PMC 1817691. Retrieved 2012-05-01.
  7. ^ a b Mooney, Chris (2011). "The Truth About Fracking". Scientific American (305): 80–85.
  8. ^ "EPA's Study of Hydraulic Fracturing and Its Potential Impact on Drinking Water Resources". EPA. Retrieved 2012-05-02.
  9. ^ Fjaer, E. (2008). "Mechanics of hydraulic fracturing". Petroleum related rock mechanics. Developments in petroleum science (2 ed.). Elsevier. p. 369. ISBN 978-0-444-50260-5.
  10. ^ 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.
  11. ^ Manthei, G.; Eisenblätter, J.; Kamlot, P. (2003). "Stress measurement in salt mines using a special hydraulic fracturing borehole tool". In Natau, Fecker & Pimentel (ed.). Geotechnical Measurements and Modelling (PDF). pp. 355–360. ISBN 90-5809-603-3. Retrieved 6 March 2012.
  12. ^ Zoback, M.D. (2007). Reservoir geomechanics. Cambridge University Press. p. 18. Retrieved 6 March 2012.
  13. ^ Laubach, S.E. (2004). "Coevolution of crack-seal texture and fracture porosity in sedimentary rocks: cathodoluminescence observations of regional fractures". Journal of Structural Geology. 26 (5). Elsevier: 967–982. doi:10.1016/j.jsg.2003.08.019. Retrieved 5 November 2011. {{cite journal}}: Unknown parameter |coauthors= ignored (|author= suggested) (help)
  14. ^ Sibson, R.H. (1975). "Seismic pumping--a hydrothermal fluid transport mechanism". Journal of the Geological Society. 131. London: Geological Society: 653–659. doi:10.1144/gsjgs.131.6.0653. Retrieved 5 November 2011. {{cite journal}}: Unknown parameter |coauthors= ignored (|author= suggested) (help)
  15. ^ 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.
  16. ^ "The Barnett Shale" (PDF). North Keller Neighbors Together.
  17. ^ a b David Wethe (19 January 2012). "Like Fracking? You'll Love 'Super Fracking'". Businessweek. Retrieved 22 January 2012.
  18. ^ "Production Decline of a Natural Gas Well Over Time". Geology.com. The Geology Society of America. 3 January 2012. Retrieved 4 March 2012.
  19. ^ Gidley, J.L. et al. (editors), "Recent Advances in Hydraulic Fracturing", SPE Monograph, SPE, Richardson, Texas, 1989.
  20. ^ Yew, C.H., "Mechanics of Hydraulic Fracturing", Gulf Publishing Company, Houston, Texas, 1997.
  21. ^ Economides, M.J. and K.G. Nolte (editors), "Reservoir Stimulation", John Wiley & Sons, Ltd., New York, 2000.
  22. ^ Banks, David (1996). "Permeability and stress in crystalline rocks". Terra Nova. 8 (3): 223–235. doi:10.1111/j.1365-3121.1996.tb00751.x. {{cite journal}}: Unknown parameter |coauthors= ignored (|author= suggested) (help); Unknown parameter |month= ignored (help)
  23. ^ Brown, Edwin Thomas (2007) [2003]. Block Caving Geomechanics (2nd ed.). Indooroopilly, Queensland: Julius Kruttschnitt Mineral Research Centre, UQ. ISBN 978-0-9803622-0-6.
  24. ^ Frank, U.; Barkley, N. (February 1995). "Remediation of low permeability subsurface formations by fracturing enhancement of soil vapor extraction". Journal of Hazardous Materials. 40 (2): 191–201. doi:10.1016/0304-3894(94)00069-S. ISSN 0304-3894. {{cite journal}}: More than one of |work= and |journal= specified (help)
  25. ^ "Geothermal Technologies Program: How an Enhanced Geothermal System Works". .eere.energy.gov. 2011-02-16. Retrieved 2011-11-02.
  26. ^ a b c d e f g h i Fact-Based Regulation for Environmental Protection in Shale Gas Development (PDF) (Report). University of Texas at Austin. 2012. Retrieved 29 February 2012. {{cite report}}: Unknown parameter |month= ignored (help) Cite error: The named reference "UT Study" was defined multiple times with different content (see the help page).
  27. ^ 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. ?.{{cite book}}: CS1 maint: multiple names: authors list (link)
  28. ^ The Breakthrough Institute. Interview with Dan Steward, former Mitchell Energy Vice President. December 2011.
  29. ^ "US Government Role in Shale Gas Fracking: An Overview"
  30. ^ a b c d e Ground Water Protection Council; ALL Consulting (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, 60. DE-FG26-04NT15455. Retrieved 24 February 2012. {{cite report}}: Unknown parameter |month= ignored (help)
  31. ^ Arthur, J. Daniel; Bohm, Brian; Coughlin, Bobbi Jo; Layne, Mark (208). Hydraulic Fracturing Considerations for Natural Gas Wells of the Fayetteville Shale (PDF) (Report). ALL Consulting. p. 10. Retrieved 2012-05-07.
  32. ^ Hartnett-White, K. (2011). "The Fracas About Fracking- Low Risk, High Reward, but the EPA is Against it" (pdf). {{cite journal}}: Cite journal requires |journal= (help); Unknown parameter |accesdate= ignored (|access-date= suggested) (help)
  33. ^ "Water Usage". Chesapeake Energy site hydraulicfracturing.com.
  34. ^ a b c Urbina, Ian (30 December 2011). "Hunt for Gas Hits Fragile Soil, and South Africans Fear Risks". The New York Times. Retrieved 23 February 2012. Covering much of the roughly 800 miles between Johannesburg and Cape Town, this arid expanse—its name [Karoo] means "thirsty land"—sees less rain in some parts than the Mojave Desert.
  35. ^ "CARBO ceramics". Retrieved 2011. {{cite web}}: Check date values in: |accessdate= (help)
  36. ^ a b Reis, John C. (1976). Environmental Control in Petroleum Engineering. Gulf Professional Publishers.
  37. ^ a b c d [1] Scott III, George L. (03-June-1997) US Patent No. 5635712: Method for monitoring the hydraulic fracturing of a subterranean formation. US Patent Publications.
  38. ^ a b c d [2]Fertl; Walter H. (15-Nov-1983) US Patent No. US4415805: Method and apparatus for evaluating multiple stage fracturing or earth formations surrounding a borehole. US Patent Publications. Cite error: The named reference "US4415805" was defined multiple times with different content (see the help page).
  39. ^ a b c d [3] Scott III, George L. (15-Aug-1995) US Patent No. US5441110: System and method for monitoring fracture growth during hydraulic fracture treatment. US Patent Publications.
  40. ^ a b c 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{{cite web}}: CS1 maint: multiple names: authors list (link)
  41. ^ 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 October 1, 2009. {{cite journal}}: Check date values in: |date= (help)
  42. ^ [energyfromshale.org "EnergyFromShale"]. EnergyFromShale. 2011. {{cite web}}: Check |url= value (help)
  43. ^ a b c d Chemicals Used in Hydraulic Fracturing (PDF) (Report). Committee on Energy and Commerce U.S. House of Representatives. April 18, 2011.
  44. ^ "Household Products Database". U.S. Department of Health and Human Services.
  45. ^ [4] Gadeken, Larry L., Halliburton Company (08-Nov-1989). Radioactive well logging method.
  46. ^ Kris Fitz Patrick (November 17, 2011). "Ensuring Safe Drinking Water in the Age of Hydraulic Fracturing".
  47. ^ ["http://www.caslab.com/Fracking-Regulations/" "Fracking Regulations"]. {{cite web}}: Check |url= value (help)
  48. ^ About Gas: Regulation. http://www.aboutgas.com.au/regulation.html.
  49. ^ 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. 17 (5). Taylor & Francis: 1039–1056. doi:10.1080/10807039.2011.605662.
  50. ^ a b "Energy In Depth" (PDF). Gasland Debunked.
  51. ^ Josh Fox, “Affirming Gasland,” http://www.gaslandthemovie.com/whats-fracking/affirming-gasland; http://1trickpony.cachefly.net/gas/pdf/Affirming_Gasland_Sept_2010.pdf (cover letter and transcribed panel discussion rebuttal of gas industry response to film Gasland.)
  52. ^ Ed Crooks (25 January 2012). "US set to require disclosure from 'frackers'". The Financial Times. Retrieved 26 January 2012.
  53. ^ Katarzyna Klimasinska (7 February 2012). "Draft Fracking Rule Has 'Good Elements,' Environmentalist Says". Businessweek. Retrieved 22 February 2012. The draft of the measure only says the information "will become a matter of public record." . . . Among his [Dusty Horwitt, senior counsel of the Environmental Working Group] concerns are an exemption from disclosure of trade secrets. "Our concern is whether the exemption would swallow the rule," he said.
  54. ^ Mall, Amy (a senior policy analyst with the Natural Resources Defense Council) (December 2011). "Incidents where hydraulic fracturing is a suspected cause of drinking water contamination". U.S. Natural Resources Defense Council. Retrieved 23 February 2012. {{cite web}}: |author= has generic name (help)
  55. ^ Lustgarten, Abrahm (November 2008). "Incidents where hydraulic fracturing is a suspected cause of drinking water contamination". ProPublica. Retrieved 20 March 2012.
  56. ^ a b c Investigation of Ground Water Contamination near Pavillion, Wyoming (PDF) (Report). EPA. Retrieved 23 March 2012. {{cite report}}: Cite uses deprecated parameter |authors= (help)
  57. ^ a b c d "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
  58. ^ a b c 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
  59. ^ a b Ramanuja, Krishna (7 Martch 2012). "Study suggests hydrofracking is killing farm animals, pets". Cornell Chronicle. Cornell University. Retrieved 9 March 2012. {{cite news}}: Check date values in: |date= (help)
  60. ^ a b Urbina, Ian (3 August 2011). "A Tainted Water Well, and Concern There May be More". The New York Times. Retrieved 22 February 2012.
  61. ^ a b Dammel, Joseph A. (2011). "Notes From Underground: Hydraulic Fracturing in the Marcellus Shale" (PDF). Minnesota Journal of Law, Science and Technology. 12 (2). University of Minnesota Law School: 773–810. Retrieved 24 February 2012.
  62. ^ Evaluation of Impacts to Underground Sources of Drinking Water by Hydraulic Fracturing of Coalbed Methane Reservoirs; National Study Final Report (PDF) (Report). EPA. June 2004. Retrieved 23 February 2011.
  63. ^ Alex Wayne (4 January 2012). "Health Effects of Fracking Need Study, Says CDC Scientist". Bloomberg Businessweek. Retrieved 29 February 2012.
  64. ^ Mark Drajem (11 January 2012). "Fracking Political Support Unshaken by Doctors' Call for Ban". Bloomberg. Retrieved 19 January 2012.
  65. ^ a b Howarth, Robert W.; Santoro, Renee; Ingraffea, Anthony (13 March 2011). "Methane and the greenhouse-gas footprint of natural gas from shale formations" (PDF). Climatic Change. 106 (4). Springer: 679–690. doi:10.1007/s10584-011-0061-5. Retrieved 2012-05-07. {{cite journal}}: Cite has empty unknown parameter: |1= (help)
  66. ^ Howarth, Robert W.; Ingraffea, Anthony (15 September 2011). "Should Fracking Stop? Extracting gas from shale increases the availability of this resource, but the health and environmental risks may be too high. Point: Yes, it's too high risk". Nature (477): 271–275. doi:10.1038/477271a.
  67. ^ Skone, Timothy J. (12 May 2011). "Life Cycle Greenhouse Gas Analysis of Natural Gas Extraction & Delivery in the United States" (PDF). National Energy Technology Laboratory. Retrieved 4 February 2012.
  68. ^ Jiang, Mohan; Griffin; Hendrickson, Chris; Jaramillo, Paulina; VanBriesen, Jeanne; Venkatesh, Aranya (2011). "Life cycle greenhouse gas emissions of Marcellus shale gas" (PDF). Environmental Research Letters. 6 (3). IOP Publishing. doi:10.1088/1748-9326/6/3/034014. Retrieved 4 February 2012. {{cite journal}}: Unknown parameter |firat2= ignored (help)
  69. ^ Hultman, Nathan; Rebois, Dylan; Scholten, Michael; Ramig, Christopher (2011). "The greenhouse impact of unconventional gas for electricity generation" (PDF). Environmental Research Letters. 6 (4). IOP Publishing. doi:10.1088/1748-9326/6/4/044008. Retrieved 4 February 2012.
  70. ^ Lashof, Dan (12 April 2011). "Natural Gas Needs Tighter Production Practices to Reduce Global Warming Pollution". Natural Resources Defense Council. Retrieved 4 February 2012.
  71. ^ Cathles, Lawrence M.; Brown, Larry; Taam, Milton; Hunter, Andrew (2011). Climatic Change. doi:10.1007/s10584-011-0333-0. {{cite journal}}: |access-date= requires |url= (help); Missing or empty |title= (help)
  72. ^ Howarth, Robert W.; Santoro, Renee; Ingraffea, Anthony (1 February 2012). "Venting and leaking of methane from shale gas development: Response to Cathles et al" (PDF). Climatic Change. Springer. doi:10.1007/s10584-012-0401-0. Retrieved 4 February 2012.{{cite journal}}: CS1 maint: date and year (link)
  73. ^ Stephen Leahy (24 January 2012). "Shale Gas a Bridge to More Global Warming". IPS. Retrieved 4 February 2012.
  74. ^ "Ozone mitigation efforts continue in Sublette County, Wyoming". Wyoming's Online News Source. March 2011.
  75. ^ Eastern Research Group, Sage Environmental Consulting (July 13, 2011). City of Fort Worth: Natural Gas Air Quality Study (PDF) (Report). City of Fort Worth. Retrieved 2012-05-07.
  76. ^ "Study: No 'significant health threats' from natural gas sites in Fort Worth". Fort Worth Star-Telegram. July 15, 2011.
  77. ^ 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.
  78. ^ a b c Schmidt, Charles (1 August 2011). "Blind Rush? Shale Gas Boom Proceeds Amid Human Health Questions". Environmental Health Perspectives. 119: a348–a353. doi:10.1289/ehp.119-a348. Retrieved 23 March 2012.
  79. ^ "Study shows air emissions near fracking sites may have serious health impacts". @theForefront. Colorado School of Public Health. 19 March 2012. Retrieved 25 April 2012.
  80. ^ http://trib.com/news/state-and-regional/blowout-brings-scrutiny-to-energy-company/article_cea4bf57-e246-5acf-ac9d-8c5587ef7f83.html
  81. ^ "EPA's Study of Hydraulic Fracturing and Its Potential Impact on Drinking Water Resources". EPA. Retrieved 24 February 2010.
  82. ^ Jad Mouawad (7 December 2009). "Dark Side of a Natural Gas Boom". The New York Times. Retrieved 3 March 2012. {{cite news}}: Unknown parameter |coauthor= ignored (|author= suggested) (help)
  83. ^ Christopher Bateman (21 June 2010). "A Colossal Fracking Mess". VanityFair.com. Retrieved 3 March 2012.
  84. ^ Jim Snyder (10 January 2012). "Pennsylvania Fracking Foes Fault EPA Over Tainted Water Response". Bloomberg. Retrieved 19 January 2012. {{cite news}}: Unknown parameter |coauthor= ignored (|author= suggested) (help)
  85. ^ Jim Efstathiou Jr. (23 December 2012). "Fracking Opens Fissures Among States as Drillers Face Many Rules". Bloomberg. Retrieved 19 January 2012. {{cite news}}: Unknown parameter |coauthor= ignored (|author= suggested) (help)
  86. ^ "The Facts Behind EPA's Dimock Two-Step". 01/23/12. Retrieved 02/09/12. {{cite news}}: Check date values in: |accessdate= and |date= (help)
  87. ^ "Gasland". 2010.
  88. ^ Honan, Edith (2010-06-17). "Film challenges safety of U.S. shale gas drilling". Reuters. Retrieved 2010-06-28.
  89. ^ "Affirming Gasland" (PDF). 2010-07. Retrieved 2010-12-21. {{cite news}}: Check date values in: |date= (help)
  90. ^ a b c Larry Jackson (8 December 2011). [http://yosemite.epa.gov/opa/admpress.nsf/1e5ab1124055f3b28525781f0042ed40/ef35bd26a80d6ce3852579600065c94e! OpenDocument "EPA Releases Draft Findings of Pavillion, Wyoming Ground Water Investigation for Public Comment and Independent Scientific Review"]. Retrieved 27 February 2012. {{cite news}}: Check |url= value (help); line feed character in |url= at position 108 (help)
  91. ^ "Groundwater Investigation: Pavillion, WY". EPA. Retrieved 6 February 2012. Pavillion, Wyoming is located in Fremont County, about 20 miles northwest of Riverton. In 2003, the estimated population was 166 residents. The concern at the site is potential groundwater contamination, based on resident complaints about smells, tastes and adverse changes in water quality of their domestic wells. The report itself is here.
  92. ^ Christopher Helman (8 December 2011). "What If Fracking Did Pollute Wyoming Water?". Forbes.com. Retrieved 6 February 2012.
  93. ^ "EPA Releases Report on Water Contamination By Fracking, As GA Pushes Fee Bills". PhillyNow blog. Philadelphia Weekly. 9 December 2011. Retrieved 6 February 2012.
  94. ^ Susan Phillips (8 December 2011). "EPA Blames Fracking for Wyoming Groundwater Contamination". StateImpact Penn­syl­va­nia. WITF, WHYY & NPR. Retrieved 6 February 2012. {{cite web}}: soft hyphen character in |work= at position 17 (help)
  95. ^ a b Department of Natural Resources. "Gasland Correction Document". Denver, CO. State of Colorado Oil & Gas Conservation Commission. p. 1. {{cite news}}: |format= requires |url= (help)
  96. ^ "Methane in Pennsylvania water wells unrelated to Marcellus shale fracturing". Oil & Gas Journal. Retrieved 14 March 2012.
  97. ^ "Gasland Correction Document" (PDF). Colorado Oil & Gas Conservation Commission. Retrieved 25 January 2012.
  98. ^ Osborn, Stephen G.; Vengosh, Avner; Warner, Nathaniel R.; Jackson, Robert B. (2011-05-09). "Methane contamination of drinking water accompanying gas-well drilling and hydraulic fracturing". Proceedings of the National Academy of Sciences. doi:10.1073/pnas.1100682108. Retrieved 2011-10-14.
  99. ^ "The Future of Natural Gas: An Interdisciplinary MIT Study" (PDF). MIT Energy Initiative. June 2011. {{cite journal}}: Cite journal requires |journal= (help)
  100. ^ Munro, Margaret (17 February 2012). "Fracking does not contaminate groundwater: study released in Vancouver". Vancouver Sun. Retrieved 3 March 2012.
  101. ^ Vaughan, Vicki (16 February 2012). "Fracturing 'has no direct' link to water pollution, UT study finds". Retrieved 3 March 2012.
  102. ^ a b "Fracturing 'has no direct' link to water pollution, UT study finds". Fuel Fix. 17 February 2012. Retrieved 20 March 2012.
  103. ^ Scott, Mark (17 October 2011). "Norway's Statoil to Acquire Brigham Exploration for $4.4 Billion". Dealb%k. New York Times. Retrieved 4 March 2012.
  104. ^ Barry Harrell (19 September 2011). "Norway-based energy company, UT agree on $5 million research program". The Austin American-Statesman. Retrieved 5 March 2012.
  105. ^ Patrick Barkham (17 April 2012). "What's the truth about fracking?". guardian.co.uk. Retrieved 25 April 2012.
  106. ^ David Caruso (2011-01-03). "44,000 Barrels of Tainted Water Dumped Into Neshaminy Creek. We're the only state allowing tainted water into our rivers". NBC Philadelphia. Associated Press. Retrieved 2012-04-28.
  107. ^ a b c Urbina, Ian (26 February 2011). "Regulation Lax as Gas Wells' Tainted Water Hits Rivers". The New York Times. Retrieved 22 February 2012.
  108. ^ http://www.nytimes.com/interactive/2011/02/27/us/natural-gas-map.html
  109. ^ "Natural Gas Drilling, the Spotlight". The New York Times. 5 March 2011. Retrieved 24 February 2012.
  110. ^ Urbina, Ian (1 March 2011). "Drilling Down: Wastewater Recycling No Cure-All in Gas Process". The New York Times. Retrieved 22 February 2012.
  111. ^ Charles Petit (2 March 2011). "Part II of the fracking water problems in PA and other Marcellus Shale country". Knight Science Journalism Tracker. MIT. Retrieved 24 February 2012. {{cite web}}: External link in |author= (help)
  112. ^ EPA (8 March 2012). "Radionuclides in public drinking water". EPA. Retrieved 4 May 2012.
  113. ^ Bauers, Sandy (21 July 2011). "Cancer patients' urine suspected in Wissahickon iodine-131 levels". Philadelphia inquirer, Carbon County Groundwater Guardians. Retrieved 25 February 2012.
  114. ^ "Shale gas fracking: MPs call for safety inquiry after tremors". BBC News. 8 June 2011. Retrieved 22 February 2012.
  115. ^ BBC News (2 November 2011). "Fracking tests near Blackpool 'likely cause' of tremors". BBC. Retrieved 22 February 2012.
  116. ^ C.J. de Pater and (2 November 2011). "Geomechanical Study of Bowland Shale Seismicity" (PDF). Cuadrilla Resources. Retrieved 22 February 2012. {{cite web}}: Unknown parameter |coauthors= ignored (|author= suggested) (help)
  117. ^ "FAQs - Earthquakes, Faults, Plate Tectonics, Earth Structure: Can we cause earthquakes? Is there any way to prevent earthquakes?". USGS. 27 October 2009. Retrieved 22 February 2012.
  118. ^ "Ohio Quakes Probably Triggered by Waste Disposal Well, Say Seismologists". Lamont-Doherty Earth Observatory Institute, Columbia University. 6 January 2012. Retrieved 22 February 2012.
  119. ^ a b Fountain, Henry (10 March 2012). "Ohio has since tightened its rules regarding the wells". National Briefing: Midwest. New York Times. Retrieved 2 April 2012. Cite error: The named reference "Fountain03102012" was defined multiple times with different content (see the help page).
  120. ^ a b Associated Press (3 March 2012). "Local zoning provisions in Pa.'s gas drilling law". USA Today. Retrieved 23 February 2012. {{cite web}}: Text "Frontpage" ignored (help); Text "newswell" ignored (help); Text "s" ignored (help); Text "text" ignored (help)
  121. ^ Suddes, Thomasn (14 Jan 2012). "'Fracking' debate exposes weaknesses in Ohio Statehouse -- term limits and the death of home rule". The Plain Dealer. Retrieved 26 March 2012.
  122. ^ Tavernise, Sabrina (14 Dec 2011). "As Gas Drilling Spreads, Towns Stand Ground Over Control Applied". The New York Times. Retrieved 26 March 2012.
  123. ^ Sheppard, Kate (23 March 2012). "For Pennsylvania's Doctors, a Gag Order on Fracking Chemicals. A new provision could forbid the state's doctors from sharing information with patients exposed to toxic fracking solutions". Mother Jones. Retrieved 23 March 2012.
  124. ^ Javers, Eamon (8 Nov 2011). "Oil Executive: Military-Style 'Psy Ops' Experience Applied". CNBC.
  125. ^ Phillips, Susan (9 Nov 2011). "'We're Dealing with an Insurgency,' says Energy Company Exec of Fracking Foes". National Public Radio.
  126. ^ "Chemicals that may be used in Australian CSG fraccing fluid" (PDF). Australian Petroleum Ptoduction & Exploration Association Limited. Retrieved 22 February 2012.
  127. ^ Stephen D. Simpson (12 July 2010). "Will The EPA Crack Down On 'Fracking'?". Investopedia. Retrieved 22 February 2012.
  128. ^ "HydraulicFracturing.com". HydraulicFracturing.com. Retrieved 2011-07-13.
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