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Hydraulic fracturing

washrigfarmair.jpgHydraulic fracturing (called "frac jobs," "frac'ing," "fracking," or "Hydrofracking") is a process that results in the creation of fractures in rocks. The fracturing is done from a wellbore drilled into reservoir rock formations to increase the rate and ultimate recovery of oil and natural gas.

Hydraulic fractures may be natural or man-made and are extended by internal fluid pressure which opens the fracture and causes it to extend through the rock. Natural hydraulic fractures include volcanic dikes, sills and fracturing by ice as in frost weathering. Man-made fluid-driven fractures are formed at depth in a borehole and extend into targeted formations. The fracture width is typically maintained after the injection by introducing a proppant into the injected fluid. Proppant is a material, such as grains of sand, ceramic, or other particulates, that prevent the fractures from closing when the injection is stopped.

Considerable controversy surrounds the current implementation of hydraulic fracturing technology in the United States. Environmental safety and health concerns have emerged and are being debated at the state and national levels

Content Table


The technique of hydraulic fracturing is used to increase or restore the rate at which fluids, such as oil, gas or water, can be produced from a reservoir, including 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 or 1,500-6,100 m). At such depth, there may not be sufficient porosity and permeability to allow natural gas and oil to flow from the rock into the wellbore at economic rates. For example, creating conductive fractures in the rock is essential to produce gas from shale reservoirs because of the extremely low natural permeability of shale, (which is measured in the microdarcy to nanodarcy range[9]). The fracture provides 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.

While the main industrial use of hydraulic fracturing is in stimulating production from oil and gas wells,[10][11][12] hydraulic fracturing is also applied to:

  • Stimulating groundwater wells[13]
  • Preconditioning rock for caving or inducing rock to cave in mining[14]
  • As a means of enhancing waste remediation processes (usually hydrocarbon waste or spills) or spills.[15]
  • Dispose of waste by injection into suitable deep rock formations
  • As a method to measure the stress in the earth.History

Hydraulic fracturing for stimulation of oil and natural gas wells was first used in the United States in 1947.[16][17] It was first used commercially by Halliburton in 1949,[16] and because of its success in increasing production from oil wells was quickly adopted, and is now used worldwide in tens of thousands of oil and natural gas wells annually. The first industrial use of hydraulic fracturing was as early as 1903, according to T.L. Watson.[18] Before that date, hydraulic fracturing was used at Mt. Airy Quarry, near Mt Airy, North Carolina where it was (and still is) used to separate granite blocks from bedrock.

Volcanic dikes and sills are examples of natural hydraulic fractures. Hydraulic fracturing incorporates results from the disciplines of fracture mechanics, fluid mechanics, solid mechanics, and porous medium flow.


A hydraulic fracture is formed by pumping the fracturing fluid into the wellbore at a rate sufficient to increase the pressure downhole to a value in excess of the fracture gradient of the formation rock. The pressure causes the formation to crack, allowing the fracturing fluid to enter and extend the crack farther into the formation. To keep this fracture open after the injection stops, a solid proppant, commonly a sieved round sand, is added to the fracture fluid. The propped hydraulic fracture then becomes a high permeability conduit through which the formation fluids can flow to the well.

Drilling a wellbore produces rock chips and fine rock particles that may enter cracks and pore space at the wellbore wall, resulting in damage to the permeability at and near the wellbore. The damage 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 mitigate this damage.

Hydraulic fracture stimulation is commonly applied to wells drilled in low permeability reservoirs. An estimated 90 percent of the natural gas wells in the United States use hydraulic fracturing to produce gas at economic rates.

The fracture fluid can be any number of fluids, ranging from water to gels, foams, nitrogen, carbon dioxide or air in some cases. Various types of proppant are used, including sand, resin-coated sand, and man-made ceramics depending on the type of permeability or grain strength needed. Radioactive sand is sometimes used so that the fracture trace along the wellbore can be measured. The injected fluid mixture is approximately 99 percent water and sand.

Microseismic monitoring is a common method for measuring the orientation and approximate size of a hydraulic fracture. Microseismic activity is measured by placing an array of geophones in a nearby wellbore. By mapping the location of small seismic events that are 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 fracture geometry.

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, high pressure treating iron, a chemical additive unit (used to accurately monitor chemical addition) low pressure pipes and gauges 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 MPa (15,000 psi) and 265 L/s (100 barrels per minute).

The location of fracturing along the length of the borehole can be controlled by inserting composite plugs, also known as bridge plugs, below and above the region to be fractured.[19] This allows a borehole to be progressively fractured along the length of the bore, without leaking fracture fluid out through previously fractured regions. Piping through the upper plug admits fracturing fluid and proppant into the working region. This method is commonly referred to as "plug and perf."

Typically, hydraulic fracturing is performed in cased wellbores and the reservoir zones to be fractured are accessed by perforating the casing at those locations.

Advances in completion technology have led to the emergence of open hole multi-stage fracturing systems. These systems effectively place fractures in specific places in the wellbore, thus increasing the cumulative production in a shorter time frame.[20]

Certain reservoirs such as the Bakken, Barnett Shale, Montney and Haynesville Shale cannot be produced using conventional methods. These formations have begun using high tech completion systems capable of mechanically fracturing at certain intervals. An alternative to the plug and perf method, multi-stage fracturing systems are capable of stimulating several stages in a single day. Compared to the weeks required by the plug and perf method, cost-effective multi-stage completion systems are quickly becoming sought after technology by oil and natural gas companies.[21]

Environmental and health effects

Many environmental and human health concerns associated with hydraulic fracturing include the contamination of ground water, risks to air quality, the migration of gases and hydraulic fracturing chemicals to the surface, and the potential mishandling of waste. The potential costs associated with possible environmental clean-up processes, loss of land value and human and animal health concerns are undetermined. For the first time, in a study published in 2010, the EPA has discovered contaminants in drinking water including: arsenic, copper, vanadium, and adamanatanes. Many of these contaminants are known to cause a variety of illnesses such as cancer, kidney failure, anaemia, and fertility problems[22]. New technological advances and appropriate state regulations are working to study and safely implement the process[23]

A number of chemicals identified in fracturing fluid are hazardous chemicals that may cause health risks that range from rashes to cancer. Some chemicals are identified as carcinogens. Some chemicals found injected into the earth identify as endocrine disruptors, which interrupts hormones and glands in the body that control development, growth, reproduction and behavior in animals and humans.

Arguments against hydraulic fracturing center around the extent to which fracturing fluid used far below the earth's surface might pollute fresh water zones, contaminate surface or near-surface water supplies, impact rock shelf causing seismic events or lead to surface subsidence. However, well casing failures and failures of the well grouting systems may have been responsible for gas migration into drinking water aquifers in Dimock, Pennsylvania. Also, water-related pollution events that occur from hydraulic fracturing get noticed on or relatively near the surface. With the transport, handling, storage and use of chemicals and chemical-laden water, accidents that release materials into the environment may occur, introducing a level of uncertainty on how deep the original source of contamination lies.

In April 2010 the state of Pennsylvania banned Cabot Oil & Gas Corp. from further drilling in the entire state until it plugs wells believed to be the source of contamination of the drinking water of 14 homes in Dimock Township, Pennsylvania. The investigation was initiated after a water well exploded on New Year's Day in 2009. The state investigation revealed that Cabot Oil & Gas Company "had allowed combustible gas to escape into the region's groundwater supplies."[24]

A well blowout in Clearfield County, Pennsylvania on June 3, 2010 sent more than 35,000 gallons of hydraulic fracturing fluids into the air and onto the surrounding landscape in a forested area. Campers were evacuated and the company EOG Resources and the well completion company C.C. Forbes have been ordered to cease all operations in the state of Pennsylvania pending investigation. The Pennsylvania Department of Environmental Protection has called this a "serious incident".[25][26]

Injection of fluid into subsurface geological structures, such as faults and fractures, reduces the effective normal stress acting across these structures. If sufficient shear stress is present, the structure may slip in shear and generate seismic events over a range of magnitudes.[citation needed] Subsidence is not directly caused by hydraulic fracturing but may occur after considerable production of oil or ground water. Subsidence occurs over reservoirs whether they have been subject to hydraulic fracturing or not because it is a result of producing fluids from the reservoir and lowering the reservoir pore pressure. The subsidence process can be associated with some seismicity. Reports of minor tremors of no greater than 2.8 on the Richter scale were reported on June 2, 2009 in Cleburne, Texas, the first in the town's 140-year history.[27]

One use of hydraulic fracturing is in stimulating water wells. In that case, the fluid used may be pure water (typically water and a disinfectant such as bleach).[citation needed] Another use of hydraulic fracturing is to remediate waste spills by injecting bacteria, air, or other materials into a subsurface contaminated zone.[citation needed]

It has been reported that the hydraulic fracturing industry has refused to publicly disclose, due to intellectual property concerns, the specific formulation of the fluids employed in the fracturing process. A "NOW on PBS" episode aired in March 2010 introduces the documentary film Gasland. The filmmaker claims that the chemicals include toxins, known carcinogens and heavy metals which may have polluted the ground water near well sites in Pennsylvania and Colorado. The film also makes a case for explosive gases entering private potable water wells, causing "flammable water".

Energy in Depth, an oil and gas industry organization has published a list of chemicals in a "typical solution used in hydraulic fracturing," but notes "The specific compounds used in a given fracturing operation will vary."[28]

The New York State Department of Environmental Conservation has published a list of chemicals used in fracturing fluids. The report addresses many issues with well fracturing.

A 2008 newspaper report states that medical personnel were inhibited in their treatment of workers injured in a fracturing accident because they did not know which specific chemicals were used. In the article, a nurse claimed she may have been exposed to the unknown chemicals on the patient's clothes.[29] Release of information, pertaining to hazardous components of any and all industrial chemicals, to medical and emergency personnel has been governed by OSHA since the 1974 Right-To-know legislation. If referenced by medical personnel, Material Safety Data Sheets will provide all information necessary for personal protection and the treatment of chemical exposure.

In the United States, a 2004 Environmental Protection Agency (EPA) study concluded that the process was safe and didn't warrant further study, because there was "no unequivocal evidence" of health risks, and the fluids were neither necessarily hazardous nor able to travel far underground. That study, however, was not intended as a general study of hydraulic fracturing, but only of its use in coalbed methane deposits, and the study did not consider impacts above ground.[30] The EPA report did find uncertainties in knowledge of how fracturing fluid migrates through rocks, and upon its release service companies voluntarily agreed to stop using diesel fuel as a component of fracturing fluid in coalbed methane walls due to public concerns of its potential as a source of benzene contamination.[31] Environmental group Riverkeeper presented a report to the EPA of over 100 cases cases of contamination.[32] It has published a report of various environmental impacts using reports from federal and state regulators.[33]

Congress has requested that the EPA undertake a new, broader study of hydraulic fracturing. The report is due to be released in 2012.[34].

The increased use of hydraulic fracturing has prompted more speculation about its environmental dangers. A 2008 investigation of benzene contamination in Colorado and Wyoming led some EPA officials to suggest hydraulic fracturing as a culprit. One of the authors of the 2004 EPA report states that it has been misconstrued by the gas-drilling industry.[30]

A potential hazard that is commonly overlooked is the venting of bulk sand silos directly to atmosphere. When they are being filled, or emptied during the fracture, a fine cloud of silica particulate will be venting directly to atmosphere. This dust has the potential to travel many kilometers on the wind directly into populated areas. While the immediate personnel are wearing personal protective equipment, families in the area of a well fracture can potentially be exposed. However, sand used for proppant is washed to remove fines and is, therefore, virtually dust free.

On 21 February 2011, the ABC's investigative journalism program Four Corners aired a program showing incidents of gas leaks into the water basin and evidence of contamination by hydraulic fracturing in Chinchilla, Queensland as a result of drilling carried out by a Queensland gas company, QGC.[35]

A 2011 Cornell University study found that, rather than being a bridge fuel, natural gas extracted by hydraulic fracturing contributes as much to global warming as coal, or more so.


In September 2010, a lawsuit was filed in Pennsylvania alleging that Southwestern Energy Company contaminated aquifers through a defective cement casing in the well.[32]


The Energy Policy Act of 2005 exempted wells which are hydraulic fractured from being re-classified as injection wells, which would place them under federal regulation under the Safe Drinking Water Act.[30] which was originally intended to regulate disposal wells. Accusations of ground water contamination have brought into question whether the exemption is appropriate and whether UIC laws should be re-interpreted.

A complete listing of the specific chemical formulation of additives used in hydraulic fracturing operations is not currently made available to landowners, neighbors, local officials, or health care providers. This practice is under scrutiny as well.

Two studies released in 2009, one by the U.S. Department of Energy and the other released by the Ground Water Protection Council, address hydraulic fracturing safety concerns. The industry contends that the chemicals in use have been adequately disclosed through Material Safety Data Sheets (MSDS) available on the OSHA website and that additional regulation is burdensome.[36] Chemicals which can be used in the fracturing fluid include kerosene, benzene, toluene, xylene, and formaldehyde.[37] These chemicals are not directly used as treating chemical additives but can be a small component of the specific chemicals used in the job.[37]

On June 8, 2010 the Wyoming Oil and Gas Conservation Commission voted to require full disclosure of the hydraulic fracturing fluids used in natural gas exploration.[38] This may aid in tracking pollutants that have migrated from hydraulically fractured gas wells.[39]

Congress has been urged to repeal the 2005 regulatory exemption under the Energy Policy Act of 2005.[40] The FRAC Act, introduced in June 2009, would eliminate the exemption and might allow producing wells to be reclassified as injection wells placing them under federal jurisdiction in states without approved UIC programs.

The New York City watershed includes a large area of the Marcellus shale formation. The NYC Dept. of Environmental Protection's position: "While DEP is mindful of the potential economic opportunity that this represents for the State, hydraulic fracturing poses an unacceptable threat to the unfiltered water supply of nine million New Yorkers and cannot safely be permitted with the New York City watershed." [41]

The New York State assembly voted 93 to 43, Nov. 30, 2010, to place a moratorium or freeze on hydraulic fracturing to give the state more time to undertake safety and environmental concerns.[42]

EPA Hydraulic Fracturing Study

The purpose of the EPA study regarding Hydraulic Fracturing is to examine the effects of hydraulic fracturing on the water supply, specifically for human consumption. The research aims to examine the full scope of the water pathway as it moves through the hydraulic fracturing process, including water that is used for the construction of the wells, the fracturing mixture, and subsequent removal and disposal. The Scientific Advisory Board reviewed the study plan in early March 2011. Research should be completed by the end of 2012, and the EPA's Hydraulic Fracturing Report is expected to be completed in 2014.

The EPA Hydraulic Fracturing Draft Study Plan can be found here. Draft Plan [43]

The U.S. FRAC Act of 2009

In June 2009 two identical bills named the FRAC Act were introduced to both the United States House and the Senate. FRAC stands for Fracturing Responsibility and Awareness of Chemicals Act. The House bill was introduced by representatives Diana DeGette, D-Colo., Maurice Hinchey D-N.Y., and Jared Polis, D-Colo. The Senate version was introduced by senators Bob Casey, D-Pa., and Chuck Schumer, D-N.Y. These bills are designed to amend the Safe Drinking Water Act. This would allow the Environmental Protection Agency to regulate hydraulic fracturing that occurs in states which have not taken primacy in UIC regulation. The bill required the energy industry to reveal what chemicals are being used in the sand-water mixture. The 111th Congress adjourned (Jan. 3, 2011) without taking action on the FRAC Act. The 112th Congress has not re-introduced the bill or an equivalent.

Background to the FRAC Act

The Act calls only for the "chemical constituents (but not the proprietary chemical formulas) used in the fracturing process." Once these constituents are determined the information must be revealed to the public through the Internet. The firms that use the fracturing process have refused to disclose this information because they claim it is a trade secret. The FRAC Act states that in any case where a physician or the State finds that a medical emergency exists, and that the chemical formulas are needed to treat the ailing individual, the firm must disclose the chemical identity to the State or physician - even if that proprietary formula is a trade-secret chemical. Material Safety Data Sheets, required by OSHA under 29 CFR 1910.1200[44] are developed and made available to first responders and other emergency planning and response officials.

ProPublica, an online journal, has published a number of reports that suggest hydraulic fracturing could be the cause of water contamination in areas surrounding drilling operations. However, the Environmental Protection Agency says that they have not been able to conclude whether fracturing is the cause of this contamination. At the same time, numerous state regulatory officials have recently confirmed that they are not aware of any confirmed instances of contamination of drinking water sources due to hydraulic fracturing in their states. The agency blames this lack of information on the 2005 Energy Policy Act because it exempts hydraulic fracturing from federal water laws.[45] The writers of the FRAC Act claim that they are attempting to protect the people who live in close proximity to fracturing from potentially dangerous chemicals leaching into ground water resources. The drilling industry does not agree with this pending policy. They see it as "an additional layer of regulation that is unneeded and cumbersome."[46] The Independent Petroleum Association of America believes that states already sufficiently regulate hydraulic fracturing. Their research suggests that federal regulation could result in the addition of about $100,000 to each new natural gas well.[47] Energy in Depth, a lobbying group, says the new regulation would be an "unnecessary financial burden on a single small-business industry, American oil, and natural gas producers." This group also claims that the FRAC Act could result in half of the United States oil wells and one third of the gas wells being closed. Also, the bill could cause domestic gas production to drop by 245 billion cubic feet per year along with four billion dollars in lost revenue to the federal government.[48] The Environmental Protection Agency claims that the section that would be amended in the Safe Drinking Water Act is flexible in that it defers regulation of fracturing and drilling to the state. The EPA also says that since most states currently have regulations on fracturing, they would most likely agree with the state's policy and there would not be much change.[47]

Fracturing method: high pressure by combustible gas mixtures or driving forces

Fracturing may be done by pumping in liquids at high pressure, using combustible gas mixtures alone or driving liquids, or using explosives to generate high-pressure high-speed gas flow (TNT or PETN up to 1,900,000 psi). In the late 1960s and early 1970s, as part of Operation Plowshare, underground nuclear explosions were tested for natural gas stimulation. The Rulison explosion multiplied the accessibility of the gas, but the gas was contaminated and unmarketable.

"Chemical Constituents in Additives/Chemicals" used in Fracturing (New York State list)

(Extracted from

CAS Number↓

Chemical Constituent↓

2634-33-51,2 Benzisothiazolin-2-one / 1,2-benzisothiazolin-3-one
95-63-61,2,4 trimethylbenzene
10222-01-22,2 Dibromo-3-nitrilopropionamide, a biocide
15214-89-82-Acrylamido-2-methylpropane sulphonic acid sodium salt polymer
46830-22-22-acryloyloxyethyl(benzyl)dimethylammonium chloride
111-76-22-Butoxy ethanol
1113-55-92-Dibromo-3-Nitriloprionamide (2-Monobromo-3-nitriilopropionamide)
104-76-72-Ethyl Hexanol
67-63-02-Propanol / Isopropyl Alcohol / Isopropanol / Propan-2-ol
26062-79-32-Propen-1-aminium, N,N-dimethyl-N-2-propenyl-chloride, homopolymer
9003-03-62-propenoic acid, homopolymer, ammonium salt
25987-30-82-Propenoic acid, polymer with 2 p-propenamide, sodium salt / Copolymer of acrylamide and sodium acrylate
71050-62-92-Propenoic acid, polymer with sodium phosphinate (1:1)
66019-18-92-propenoic acid, telomer with sodium hydrogen sulfite
107-19-72-Propyn-1-ol / Propargyl alcohol
51229-78-83,5,7-Triaza-1-azoniatricyclo[,7]decane, 1-(3-chloro-2-propenyl)-chloride,
127087-87-04-Nonylphenol Polyethylene Glycol Ether Branched / Nonylphenol ethoxylated / Oxyalkylated Phenol
64-19-7Acetic acid
68442-62-6Acetic acid, hydroxy-, reaction products with triethanolamine
108-24-7Acetic Anhydride

Environmental Research Assistant: Mark Olsthoorn

Among ththose advocating a slower approach to natural gas development is Mark Olsthoorn, a faculty research assistant at the University of Maryland's Center for Integrative Environmental Research.

Climate and greenhouse gas issues

Natural gas from shale, produced with the hydraulic fracturing technique, is often touted as  a ‘bridge fuel’ toward a sustainable energy system. ‘Bridge fuel’ refers to the capacity of natural gas to reduce carbon emissions on the short term, when renewable energy sources still play a minor role, while facilitating the growth of renewables. This climate friendliness of natural gas from shale hinges on three premises: (1) natural gas has lower greenhouse gas emissions than other fossil fuels it should displace, (2) the extra natural gas entering the market will indeed displace coal and oil in power generation, and (3) the flexibility of natural gas-fired power plants to fluctuate its output allows it to work well in conjunction with intermittent renewable sources such as solar and wind, which coal-fired and nuclear power plants are much less suited to do.

The following paragraphs take a closer look at first two critical premises, which are most uncertain.

Is natural gas from shale cleaner than coal and oil?

Natural gas has a carbon intensity[1] that is about 55 percent the carbon intensity of coal and  71 percent that of oil[2][3]. When natural gas is burned, it will emit much less CO2 per unit of energy released than does coal or oil. Natural gas’s major contribution to short-term emissions reduction would be through displacing coal in electricity generation. Gas-fired generation is generally more efficient than coal-fired generation, adding to natural gas’s climate advantage over coal. However, a complete comparison of a megawatt-hour of electricity from coal and shale gas would look at the life-cycle and include emissions released during the whole chain of well drilling and completion, production, processing, distribution and end-use. During all phases of the life cycle emissions of greenhouse gases occur. These include emissions from power consumed in facilities such as processing plants and compressor stations and methane that is vented or leaked. Few studies yet exist that analyze life cycle emissions from shale gas, but those that do[4][5][6] agree that for natural gas from shale produced with horizontal wells and high-volume hydraulic fracturing upstream emissions are higher than from conventional gas. The two main reasons for the difference are: (1) hydraulic fracturing is an energy-intensive process, due to the high volumes of fluids that need to be injected into the well at high pressures and trucked to and from the well site, and (2) flowback of fluids after the fracturing job bring along significant quantities of natural gas that can escape to the atmosphere. And like in conventional gas production, gas is vented and leaked form storage sites and transmission lines. Natural gas is mostly methane (CH4), the second-most important greenhouse gas after CO2 and much more potent on a per-kg basis. How much more potent is expressed by the global warming potential[7] (GWP) and depends on the timeframe considered. Methane is much shorter-lived than CO2, which keeps trapping heat for centuries. According to the IPCC[8], methane is 72 times more potent than CO2 over a 20-year (GWP20 = 72), which reduces to 25 times over 100 years (GWP100 = 25). Which timeframe to use is science-informed political decision. The Kyoto protocol uses the 100-year time frame, but some argue that a shorter timeframe is appropriate, because of the possibility of the climate passing tipping points in the coming decades, beyond which irreversible, large-scale changes can occur.

Due to the high GWP of methane, small leaks can have significant consequences for the cleanliness of natural gas from shale. Furthermore, the larger the share of methane in the life-cycle greenhouse gas footprint, the more sensitive the outcome is to the choice of the GWP timeframe.

Two studies that analyzed the life-cycle greenhouse gas footprint of shale gas came to very different conclusions. A paper by a team of researcher from Cornell University concluded that “[c]ompared to coal, the footprint of shale gas is at least 20% greater and perhaps more than twice as great on the 20-year horizon and is comparable when compared over 100 years,”[9] whereas according to an analysis by the United States Department of Energy’s National Energy Technology Laboratory (NETL)[10] methane plays a much smaller role and the footprint of shale gas per MWh of electricity generated is still less than half that of coal and not as sensitive to the choice of the GWP timeframe. The NETL study points out that much methane that is produced but not sold is used to power the natural gas system itself and not leaked to the atmosphere.

Unfortunately, data quality and availability present barriers to a conclusive answer to the question whether and to what extent shale gas is cleaner than coal.

As leaked methane equals leaked revenue, an incentive exists to minimize methane emissions in the supply chain. A report by the U.S. Government Accountability Office[11] on vented and flared natural gas from onshore federal gas leases noted that around 40 percent of the vented and flared natural gas could be economically captured with currently available control technologies.

Will natural gas from shale displace coal and oil in power generation?

If shale gas is indeed cleaner than coal, it needs to directly lead to a decrease in the use of coal to meet its promise of short-term emissions reduction. A 2010 study by the MIT Energy Initiative[12] showed that the potential for quick climate gains certainly exists in the U.S.. Displacing coal generation with additional generation from excess capacity of existing natural gas combined cycle (NGCC) could reduce CO2 emissions in the power sector on the order of 10 percent in the near term without major capital investments.

However, as the MIT study also points out, because of its lower price, coal-fired generation is generally dispatched before natural gas-fired generation. And there are other studies[13][14] that confirm that abundant and inexpensive natural gas from shale will not by itself lead to emission cuts, but rather foster greater consumption and displace the use of nuclear and renewable sources, leading to higher CO2 emissions. In its Annual Energy Outlook 2011[15], the U.S. Energy Information Administration projects a modest growth of the use of both natural gas and coal, not a replacement. If no carbon policy is in place to provide an incentive that reverses the dispatch order of coal- and gas-fired generation and promote renewable sources, it can not be expected that hydraulic fracturing of shale resources will create a bridge-fuel to a low-carbon energy supply.

[1]  Carbon intensity is the amount of carbon by weight emitted per unit of energy consumed. A common measure of carbon intensity is weight of carbon per British thermal unit (Btu) of energy. From:


[3] EPA. 2011. Inventory of U.S. Greenhouse Gas Emissions and Sinks: 1990-2009, Annex 2, Table A-36.

[4] Skone, Timothy J. 2011. Life Cycle Greenhouse Gas Analysis of Natural Gas Extraction & Delivery in the United States. Presented at Cornell University Lecture Series, May 12, 2011.

[5] Howarth et al. Climate Change Letters (2011) 106:679-690

[6] Wood. R., et al: 2011, Shale gas: a provisional assessment of climate change and environmental impacts. A report commissioned by the Cooperative and undertaken by researchers at the Tyndall Centre, University

of Manchester

[7] Global Warming Potential is “the ratio of the radiative forcing that would result from the emission of one kilogram of a greenhouse gas to that from the emission of one kilogram of carbon dioxide over a fixed period of time, such as 100 years.”

[8] IPCC. 2007. Fourth Assessment Report: Climate Change 2007. Working Group I: The Physical Science Basis. 2.10.2 Direct Global Warming Potentials.

[9] Howarth et al. Climate Change Letters (2011) 106:679-690. Available at:

[10] Skone, Timothy J. 2011. Life Cycle Greenhouse Gas Analysis of Natural Gas Extraction & Delivery in the United States. Presented at Cornell University Lecture Series, May 12, 2011.

[11] United States Government Accountability Office. 2010. Federal Oil and Gas Leases: Opportunities Exist to Capture Vented and Flared Natural Gas, Which Would Increase Royalty Payments and Reduce Greenhouse Gases. GAO-11-34 October 29, 2010. Available at:

[12] MIT Energy Initiative. 2010. The Future of Natural Gas - Interim Report. Massachusetts Institute of Technology, Cambridge, Massachusetts.

[13] Brown et al. 2009. Natural gas: a bridge fuel to a low-carbon future? Issue Brief 09-11, Resources for the Future, Washington, DC

[14] Wood. R., et al: 2011, Shale gas: a provisional assessment of climate change and environmental impacts. A report commissioned by the Cooperative and undertaken by researchers at the Tyndall Centre, University

of Manchester

[15] United States Department of Energy Energy Information Administration. Annual Energy Outlook 2011.

Representative of the Ground Water Protection Council : Mike Nickolaus

Mike Nickolaus is the Special Projects Director ofthe Ground Water Protection Council (GWPC). The GWPC is the national association of the state groundwater regulatory agencies in the US.

Chemical Disclosure

In recent years, the practice of hydraulic fracturing has come under closer scrutiny by the public and the media.  Reports alleging contamination of ground water related to hydraulic fracturing have sparked a high level of interest in the practice.  The increase in drilling activity in areas such as the Marcellus shale in New York, Pennsylvania and West Virginia has led to questions about the safety of this well completion practice.  While states have regulated the practice through well construction and completion requirements for many years, there is still a belief on the part of many that the practice is unregulated.  This has led to calls for federal regulation.  One of the chief concerns about hydraulic fracturing has centered on the chemicals used in the process.

FracFocusWelcomeScreen.jpgThe practice of hydraulic fracturing of oil and gas wells uses a variety of chemical constituents to enhance the production of hydrocarbons from otherwise inaccessible oil and gas bearing zones.  The use of chemicals presents potential problems relative to their handling, use, and post use management.  Information about the chemicals used in hydraulic fracturing is widely distributed, difficult to access, variable in nature and content, and not easily understood by the non-technical person.  National attention to the process of hydraulic fracturing and the chemicals used in hydraulic fracturing has led to a lack of informed understanding.

A unified, simplified and nationwide system for disclosing the chemicals used in hydraulic fracturing was clearly needed. That is the purpose of “FracFocus” the Hydraulic Fracturing Chemical Registry.  A joint project of the Ground Water Protection Council and the Interstate Oil and Gas Compact Commission, this voluntary registry uses a web based interface such as the one shown above to provide access to the public about the chemicals used in the hydraulic fracturing of wells on a well by well basis.  Participating companies upload information about the chemicals used in a hydraulic fracturing job using a template that contains information such as the location of the well, the date of the hydraulic fracturing job, the chemicals used in the job, the Chemical Abstract Service (CAS) numbers, when available, and the relative proportions of chemicals used.  While some chemicals used during the job may not be listed, these are designed to be limited to chemicals that can be kept proprietary for purposes of the MSDS.  In addition to specific well information, the site also contains links to information about chemical formulas, the process of hydraulic fracturing, the means used to protect ground water during hydraulic fracturing, the CAS, state regulatory agencies, EPA and USGS sites and the IOGCC’s GroundWorks® website; which contains additional information about hydraulic fracturing.

There are several states that have developed legislation or rules requiring submission of chemical information from hydraulic fracturing and at least 3 of these states has decided to use the FracFocus website as a means to implement mandatory reporting.

Hydrogeologist and Environmental Consultant: John A. Conrad

Needs expanding ...


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 - Instantaneous 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.
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 two major functions 1) Open and extend the fracture; 2) Transport the proppant along the fracture length.
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.
Concise slang
"Fracing" (sometimes spelled "fracking"[49] primarily in media) is a shortened version of fracturing.


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