Shale gas
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For gas generated by oil shale pyrolysis, see Oil shale gas.
File:EIA World Shale Gas Map.png
48 Shale basins in 38 countries, as per the EIA
Shale gas is natural gas that is found
trapped within shale
formations.[1] Shale gas has
become an increasingly important source of natural gas in the United States
since the start of this century, and interest has spread to potential gas
shales in the rest of the world. In 2000 shale gas provided only 1% of U.S.
natural gas production; by 2010 it was over 20% and the U.S. government's Energy
Information Administration predicts that by 2035, 46% of the United
States' natural gas supply will come from shale gas.[2]
Some analysts expect that shale gas will
greatly expand worldwide energy supply.[3] China is estimated to have
the world's largest shale gas reserves.[4]
A study by the Baker Institute
of Public Policy at Rice University concluded
that increased shale gas production in the US and Canada could help prevent
Russia and Persian Gulf countries from dictating higher prices for the gas they
export to European countries.[5]
The Obama administration
believes that increased shale gas development will help reduce greenhouse gas
emissions[6] (in 2012, The US carbon dioxide
emissions dropped to a 20-year low[7]).
Some studies have alleged that the extraction and use of shale gas may result
in the release of more greenhouse gases than conventional natural gas.[8][9] Other recent studies point to high decline
rates of some shale gas wells as an indication that shale gas production may
ultimately be much lower than is currently projected.[10][11]
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Contents [hide]
1 History
2 Geology
3 Environment
3.1 Climate
3.2 Water and air
quality
3.3 Earthquakes
4 Economics
5 See also
6 References
7 External links
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[edit]
History
Derrick and platform of drilling gas wells in
Marcellus Shale (Pennsylvania, USA).
Shale gas was first extracted as a resource in Fredonia, NY in 1821,[12][13] in shallow, low-pressure fractures. Horizontal
drilling began in the 1930s, and in 1947 a well was first fracked
in the U.S.[2] Work on
industrial-scale shale gas production did not begin until the 1970s, when
declining production potential from conventional gas deposits in the United
States spurred the federal government to invest in R&D and demonstration
projects[14] that ultimately led to directional
and horizontal drilling, microseismic imaging, and massive hydraulic
fracturing. Up until the public and private R&D and demonstration projects
of the 1970s and 1980s, drilling in shale was not considered to be commercially
viable.
Faced with declining natural gas reserves, the
federal government made investments in many supply alternatives, including
shale gas with the Eastern Gas Shales Project in 1976 and the annual FERC-approved
research budget of the Gas Research Institute, where the federal government
began extensive research funding in 1982, disseminating the results to
industry.[2] The federal government also provided
tax credits and rules benefiting the industry in the 1980 Energy Act.[2] The Department of Energy later partnered with private
gas companies to complete the first successful air-drilled multi-fracture
horizontal well in shale in 1986. The federal government further incentivized
drilling in shale via the Section 29 tax credit for unconventional gas from
1980-2000. Microseismic imaging, a crucial input to both hydraulic fracturing
in shale and offshore oil
drilling, originated from coalbeds research at Sandia National
Laboratories. In 1991 the Department of Energy subsidized Texas gas
company Mitchell Energy's first horizontal drill in the Barnett Shale in north
Texas.[citation needed]
Mitchell Energy utilized all these component
technologies and techniques to achieve the first economical shale fracture in
1998 using an innovative process called slick-water fracturing.[15][16][17] Since then, natural gas from shale
has been the fastest growing contributor to total primary energy (TPE) in the
United States, and has led many other countries to pursue shale deposits.
According to the IEA, shale gas could increase technically recoverable natural
gas resources by almost 50%.[18]
[edit]
Geology
File:GasDepositDiagram.jpg
Illustration of shale gas compared to other
types of gas deposits.
Because shales ordinarily have insufficient permeability
to allow significant fluid flow to a well bore, most shales are not commercial
sources of natural gas. Shale gas is one of a number of unconventional sources
of natural gas; others include coalbed methane, tight sandstones, and methane hydrates. Shale
gas areas are often known as resource plays[19] (as opposed to exploration plays). The
geological risk of not finding gas is low in resource plays, but the potential
profits per successful well are usually also lower.[citation needed]
Shale
has low matrix
permeability, so gas production in commercial quantities requires fractures to
provide permeability. Shale gas has been produced for years from shales with
natural fractures; the shale gas boom in recent years has been due to modern
technology in hydraulic
fracturing (fracking) to create extensive artificial fractures
around well bores.[citation needed]
Horizontal drilling
is often used with shale gas wells, with lateral lengths up to 10,000 feet
(3,000 m) within the shale, to create maximum borehole surface area in
contact with the shale.[citation needed]
Shales that host economic quantities of gas
have a number of common properties. They are rich in organic material (0.5% to
25%),[20] and are usually mature petroleum source rocks in the
thermogenic gas window, where high heat and pressure have converted petroleum
to natural gas. They are sufficiently brittle and rigid enough to maintain open
fractures.
Some of the gas produced is held in natural
fractures, some in pore spaces, and some is adsorbed onto the organic
material. The gas in the fractures is produced immediately; the gas adsorbed onto
organic material is released as the formation pressure is drawn down by the
well.[citation needed]
[edit]
Environment
See also: Natural gas
See also: Hydraulic
fracturing
The extraction and use of shale gas can affect
the environment through the leaking of extraction chemicals and waste into
water supplies, the leaking of greenhouse gasses during
extraction, and the pollution caused by the improper processing of natural gas.
A challenge to preventing pollution is that shale gas extractions varies widely
in this regard, even between different wells in the same project; the processes
that reduce pollution sufficiently in one extraction may not be enough in
another.[2]
[edit]
Climate
US President Obama's administration has
sometimes promoted shale gas, in part because of their belief that it releases
fewer greenhouse gas
(GHG) emissions than other fossil fuels, but some scientists have urged caution[citation needed]. In a May 2010
letter to President Obama, the Council of Scientific Society Presidents
cautioned against a national policy of developing shale gas without a more
certain scientific basis for the policy. This umbrella organization that
represents 1.4 million scientists noted that the impact of shale gas on global
warming might be substantially stronger than previously estimated.[21]
In late 2010, the U. S. Environmental
Protection Agency[22]
issued a new report, the first update on emission factors for greenhouse gas
emissions by the oil and gas industry by the EPA since 1996. In this new
report, the EPA concluded that shale gas emits larger amounts of methane, a potent
greenhouse gas, than does conventional gas, but still far less than coal.
Methane is a very powerful greenhouse gas, although it stays in the atmosphere
for only one tenth as long a period as carbon dioxide. Recent evidence suggests
that methane has a global warming potential (GWP) that is 105-fold greater than
carbon dioxide when viewed over a 20-year period and 33-fold greater when
viewed over a 100-year period, compared mass-to-mass.[23] However, the U.N. Intergovernmental
Panel on Climate Change (IPCC), a pre-eminent authority on this
issue, ascribes a GWP of only 25 to methane over a 100-year period, and only 72
over a 20-year period.[24]
A 2011 study published in Climatic Change Letters controversially claimed that
the production of electricity using shale gas may lead to as much or more life-cycle
GWP than electricity generated with oil or coal.[25]
In that peer-reviewed paper, Cornell University
professor Robert W. Howarth, a marine ecologist, and colleagues claimed that
once methane leak and venting impacts are included, the life-cycle greenhouse
gas footprint of shale gas is far worse than those of coal and fuel oil when
viewed for the integrated 20-year period after emission. On the 100-year
integrated time frame, this analysis claims shale gas is comparable to coal and
worse than fuel oil. However, numerous studies have pointed out critical flaws
with that paper and/or come to completely different conclusions, including
assessments by experts at the U.S. Department of Energy,[26] peer-reviewed studies by Carnegie Mellon
University[27]
and the University of Maryland,[28]
and even 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."[29] In January 2012, Howarth's own colleagues at Cornell University,
Lawrence Cathles et al., responded with their own peer-reviewed assessment,
noting 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." The author of
that response, Lawrence Cathles, concludes 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."[30]
[edit]
Water and air quality
Chemicals are added to the water to facilitate
the underground fracturing process that releases natural gas. Fracturing fluid
is primarily water and approximately 0.5% chemical additives (friction reducer,
agents countering rust,
agents killing microorganism). Since (depending on the size of the area)
millions of liters of water are used, this means that hundreds of thousands
liters of chemicals are often injected into the soil.[31] Only about 50% to 70% of the resulting volume
of contaminated water is recovered and stored in above-ground ponds to await
removal by tanker. The remaining "produced water" is left in the
earth where it can lead to contamination of groundwater aquifers, though the
industry deems this "highly unlikely". However the wastewater from
such operations often lead to foul-smelling odors and heavy metals
contaminating the local water supply above-ground.[32]
Besides using water and chemicals however, it
is also possible to frack shale gas with only liquified
propane gas. This reduces the environmental degradation
considerably. The method was invented by GasFrac, of Alberta, Canada.[33]
The 2010 U.S. documentary film Gasland by Josh Fox,
which focuses on the impact of hydraulic fracturing, is critical of the
industry's assertions of its safety and its exemption from the Safe Drinking
Water Act in the Energy Policy
Act of 2005.[citation needed]
A study published in May 2011 concluded that
fracking has seriously contaminated shallow groundwater supplies in
northeastern Pennsylvania with flammable methane. However, the study does not
discuss how pervasive such contamination might be in other areas drilled for
shale gas.[34]
The United States
Environmental Protection Agency (EPA) announced 23 June 2011 that it
will examine claims of water pollution related to hydraulic fracturing in
Texas, North Dakota, Pennsylvania, Colorado and Louisiana.[35] On 8 December 2011, the EPA issued a draft
finding which stated that groundwater contamination in Pavilion, Wyoming may be
the result of fracking in the area. The EPA stated that the finding was
specific to the Pavilion area, where the fracking techniques differ from those
used in other parts of the U.S. Doug Hock, a spokesman for the company which
owns the Pavilion gas field, said that it is unclear whether the contamination
came from the fracking process.[36]
Wyoming's Governor Matt Mead called the EPA draft report "scientifically
questionable" and stressed the need for additional testing.[37] The Casper Star-Tribune also reported on 27
December 2011, that the EPA's sampling and testing procedures "didn’t
follow their own protocol" according to Mike Purcell, the director of the
Wyoming Water Development Commission.[38]
A 2011 study by the Massachusetts Institute of
Technology concluded that "The environmental impacts of shale development
are challenging but manageable." The study 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". This study blames known
instances of methane contamination on a small number of sub-standard
operations, and encourages the use of industry best practices to prevent such
events from recurring.[39]
In a report dated July 25, 2012, The U.S.
Environmental Protection Agency announced that "it has completed its
sampling of private drinking water wells in Dimock, Pa. Data previously
supplied to the agency by residents, the Pennsylvania Department of Environmental
Protection and Cabot Oil and Gas Exploration had indicated the potential for
elevated levels of water contaminants in wells, and following requests by
residents EPA took steps to sample water in the area to ensure there were not
elevated levels of contaminants. Based on the outcome of that sampling, EPA has
determined that there are not levels of contaminants present that would require
additional action by the Agency." [40]
[edit]
Earthquakes
On 26 April 2012, Asahi Shimbun reported
that United States
Geological Survey scientists have been investigating the recent
increase in the number of magnitude
3 and greater earthquake
in the midcontinent of the United States.
Beginning in 2001, the average number of earthquakes occurring per year of
magnitude 3 or greater increased significantly, culminating in a six-fold
increase in 2011 over 20th century levels. A researcher in Center for
Earthquake Research and Information of University of
Memphis assumes water pushed back into the fault tends to cause
earthquake by slippage of fault.[41][42]
Another instance of earthquake linked to shale
gas extraction happened in 2011 in England [North-West] and led to the company
Cuadrilla Resources having to suspend all operations.[43][44]
On June 19, 2012 The United States Senate
Committee on Energy & Natural Resources held a hearing entitled,
"Induced Seismicity Potential in Energy Technologies." Dr. Murray
Hitzman, the Charles F. Fogarty Professor of Economic Geology in the Department
of Geology and Geological Engineering at the Colorado School of Mines in
Golden, CO testified that "About 35,000 hydraulically fractured shale gas
wells exist in the United States. Only one case of felt seismicity in the United
States has been described in which hydraulic fracturing for shale gas
development is suspected, but not confirmed. Globally only one case of felt
induced seismicity at Blackpool, England has been confirmed as being caused by
hydraulic fracturing for shale gas development." [45]
[edit]
Economics
Although shale gas has been produced for more
than 100 years in the Appalachian
Basin and the Illinois Basin
of the United States, the wells were often marginally economical. Higher
natural-gas prices in recent years[when?] and advances in
hydraulic fracturing and horizontal completions have made shale-gas wells more
profitable.[46]
As of June 2011, the validity of the claims of economic viability of these
wells has begun to be publicly questioned.[47]
Shale gas tends to cost more to produce than gas from conventional wells,
because of the expense of the massive hydraulic
fracturing treatments required to produce shale gas, and of
horizontal drilling.[48]
Total published estimates for UK shale gas resources by companies holding shale
gas (Cuadrilla, Igas, Dart, Eden) drilling licenses are approximately
255 trillion cubic feet (7.2 trillion cubic metres).[49] However it is estimated that only around
10-15% of this is recoverable and can therefore be treated as reserves. There
are further questions around the proportion which can be economically
recovered. This compares to UK gas consumption of 3.5 trillion cubic feet
(99 billion cubic metres) per year. However the cost of extracting this gas
with existing technology would be probably be more than $200 per barrel of oil
equivalent (UK North Sea oil prices were about $120 per barrel in April 2012).[50]
North America has been the leader in developing
and producing shale gas. The great economic success of the Barnett Shale play in Texas in particular has
spurred the search for other sources of shale gas across the United States and Canada.[citation needed]
Research has calculated the 2011 worth of the
global shale-gas market as $26.66bn.[51]
However, a June, 2011 New York Times
investigation of industrial emails and internal documents found that the
financial benefits of unconventional shale gas extraction may be less than
previously thought, due to companies intentionally overstating the productivity
of their wells and the size of their reserves. However, no criminal
investigations have been made on these serious allegations.[52]
In first quarter 2012, USA imported 840 Bcf
(785 from Canada) while exporting 400 Bcf (mostly to Canada); both mainly by
pipeline.[53] Almost none is exported by ship as
LNG, as that would require expensive facilities. Prices have gone down to
$3/MMBtu due to shale gas.[54]
One of the byproducts of shale gas exploration
is the opening up of deep underground shale deposits to "tight oil"
or shale oil production. By 2035, shale oil production could "boost the
world economy by up to $2.7 trillion, a PricewaterhouseCoopers (PwC) report
says. It has the potential to reach up to 12 percent of the world’s total oil
production — touching 14 million barrels a day — “revolutionizing” the global
energy markets over the next few decades." [55]
[edit]
See also
[edit]
References
2.
^ a b c d e Stevens, Paul
(August 2012). "The 'Shale
Gas Revolution': Developments and Changes". Chatham House. Retrieved
2012-08-15.
3.
^ Clifford Krauss, "New way to
tap gas may expand global supplies," New York Times, 9
October 2009.
4.
^ Staff (5 April
2011) World Shale Gas
Resources: An Initial Assessment of 14 Regions Outside the United States
US Energy Information Administration, Analysis and Projections, Retrieved 26
August 2012
5.
^ Rice University,
News and Media Relations (21 July 2011): Shale Gas and U.
S. National Security, accessed 12 November 2012.
6.
^ White House,
Office of the Press Secretary, Statement on
U.S.-China shale gas resource initiative, 17 November 2009.
7.
^ Carey, Julie M.
(7 December 2012) Surprise Side
Effect Of Shale Gas Boom: A Plunge In U.S. Greenhouse Gas Emissions
Forbes magazine, Retrieved 21 February 2013
8.
^ Howarth RW,
Santoro R, and Ingraffea A (2011). Methane and the greenhouse gas footprint of
natural gas from shale formations. Climatic Change Letters, doi:10.1007/s10584-011-0061-5,
[1]
9.
^ Shindell DT,
Faluvegi G, Koch DM, Schmidt GA, Unger N, and Bauer SE. (2009). Improved
Attribution of Climate Forcing to Emissions. Science, 326(5953):
716-718, [2]
10.
^ David Hughes (May
2011). "Will Natural Gas Fuel America in the 21st Century?" Post
Carbon Institute, [3]
11.
^ Arthur Berman (8
Feb. 2011), "After the gold rush: A perspective on future U.S. natural gas
supply and price," The Oil Drum, [4]
13.
^ "New York's
natural gas history - a long story, but not the final chapter"
(pdf). Retrieved 17 May 2012.
15.
^ Miller, Rich;
Loder, Asjylyn; Polson, Jim (6 February 2012). "Americans
Gaining Energy Independence". Bloomberg. Retrieved 1
March 2012.
20.
^ US Department of
Energy, "Modern shale gas development in the United States," April
2009, p.17.
22.
^ Environmental
Protection Agency "Greenhouse
Gas Emissions Reporting from the Petroleum and Natural Gas Industry, Background
Technical Support Document, posted to web 30 November 2010.
23.
^ Shindell DT,
Faluvegi G, Koch DM, Schmidt GA, Unger N, and Bauer SE (2009). Improved
attribution of climate forcing to emissions. Science 326: 716-718.
24.
^ Intergovernmental
Panel on Climate Change, "Direct Global Warming Potentials," IPCC
Fourth Assessment Report, 2007 [7]
25.
^ Howarth RW,
Santoro R, and Ingraffea A (2011). Climatic Change Letters, doi:10.1007/s10584-011-0061-5,
[8]
26.
^ Timothy J. Skone,
"Life Cycle Greenhouse Gas Analysis of Natural Gas Extraction &
Delivery in the United States." National Energy Technology Laboratory, 12
May 2011 [9]
27.
^ Mohan Jiang et
al. (2011), "Life cycle greenhouse gas emissions of Marcellus shale
gas." Environmental Research Letters, doi:10.1088/1748-9326/6/3/034014,
[10]
28.
^ Hultman et
al (2011), "The greenhouse impact of unconventional gas for
electricity generation." Environmental Research Letters, doi:10.1088/1748-9326/6/4/044008,
[11]
29.
^ Dan Lashof,
"Natural Gas Needs Tighter Production Practices to Reduce Global Warming
Pollution," 12 April 2011 [12]
34.
^ Richard A. Kerr
(13 May 2011). "Study:
High-Tech Gas Drilling Is Fouling Drinking Water". Science
Now 332: 775. Retrieved 27 June 2011.
36.
^ Gruver, Mead (8
December 2011). "EPA
theorizes fracking-pollution link". Associated Press. Retrieved
10 December 2011.
39.
^ MIT Energy
Initiative (2011). "The Future
of Natural Gas: An Interdisciplinary MIT Study". MIT Energy
Initiative: 7,8 accessdate = 29 July 2011.
41.
^ "シェールガス採掘、地震誘発？米中部、M3以上6倍"
[Magnitude 3 and greater earthquakes 6 fold in the midcontinent of the United
States. Beginning in 200. extracted shale gas induce earthquakes ?].
Asahi Shimbun
(in Japanese) (Tokyo). 2012-04-26. p. Page 1. Retrieved 2012-04-26.
42.
^ Is the Recent
Increase in Felt Earthquakes in the Central U.S. Natural or Manmade?
United States
Geological Survey, 11 April 2012
46.
^ Simon Mauger,
Dana Bozbiciu (2011). "How
Changing Gas Supply Cost Leads to Surging Production".
Retrieved 10 May 2011.
47.
^ Ian Urbina (25
June 2011). "Insiders
Sound an Alarm Amid a Natural Gas Rush". The New York Times.
Retrieved 26 June 2011.
50.
^ Gloyston, Henning
and Johnstone, Christopher (17 April 2012) Exclusive - UK
has vast shale gas reserves, geologists say Reuters Edition UK,
Accessed 17 April 2012
52.
^ Urbina, Ian (25
June 2011). "Insiders
Sound an Alarm Amid a Natural Gas Rush". New York Times.
Retrieved 28 June 2011.; Urbina, Ian (27 June 2011). "S.E.C.
Shift Leads to Worries of Overestimation of Reserves". New
York Times. Retrieved 28 June 2011.
53.
^ Caudillo, Yvonne.
""
pp1+19-22. United States
Department of Energy. Retrieved: 25 August 2012.
54.
^ Philips, Matthew.
"Strange
Bedfellows Debate Exporting Natural Gas" page 2,
BusinessWeek 22 August
2012. Retrieved: 25 August 2012.
55.
^ Syed Rashid
Husain. "Shale Gas Revolution Changes Geopolitics." Saudi Gazette. 24
Feb 2013. [18]
[edit]
External links
• Marcellus Gas
Production and Distribution - The Institute for
Energy and Environmental Research for Northeastern Pennsylvania.
• Unconventional
Gas and Implications for the LNG Market
by Christopher Gascoyne and Alexis Aik. This is a working paper written for the
2011 Pacific Energy Summit hosted by the National Bureau
of Asian Research.
• Haynesville: A
Nation's Hunt for an Energy Future, a 2010
documentary which explores the microchasm of a shale gas discovery in Northwest
Louisiana (in the Haynesville Shale) and the impact of that discovery along
with shale gas as a whole on the United States
energy economy
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