Tight oil (also known as shale oil, shale-hosted oil or light tight oil, abbreviated LTO) is
light crude oil Light crude oil is liquid petroleum that has a low density and flows freely at room temperature. It has a low viscosity, low specific gravity and high API gravity due to the presence of a high proportion of light hydrocarbon fractions. It generally ...
contained in
unconventional petroleum
Petroleum, also known as crude oil, or simply oil, is a naturally occurring yellowish-black liquid mixture of mainly hydrocarbons, and is found in geological formations. The name ''petroleum'' covers both naturally occurring unprocessed crud ...
-bearing formations of low
permeability, often
shale
Shale is a fine-grained, clastic sedimentary rock formed from mud that is a mix of flakes of clay minerals (hydrous aluminium phyllosilicates, e.g. kaolin, Al2 Si2 O5( OH)4) and tiny fragments (silt-sized particles) of other minerals, especiall ...
or tight sandstone.
[
] Economic production from tight oil formations requires the same
hydraulic fracturing
Fracking (also known as hydraulic fracturing, hydrofracturing, or hydrofracking) is a well stimulation technique involving the fracturing of bedrock formations by a pressurized liquid. The process involves the high-pressure injection of "fra ...
and often uses the same
horizontal well technology used in the production of
shale gas. While sometimes called "shale oil", tight oil should not be confused with
oil shale (shale rich in
kerogen
Kerogen is solid, insoluble organic matter in sedimentary rocks. Comprising an estimated 1016 tons of carbon, it is the most abundant source of organic compounds on earth, exceeding the total organic content of living matter 10,000-fold. It ...
) or
shale oil
Shale oil is an unconventional oil produced from oil shale rock fragments by pyrolysis, hydrogenation, or thermal dissolution. These processes convert the organic matter within the rock ( kerogen) into synthetic oil and gas. The resulting ...
(oil produced from oil shales).
[
] Therefore, the
International Energy Agency
The International Energy Agency (IEA) is a Paris-based autonomous intergovernmental organisation, established in 1974, that provides policy recommendations, analysis and data on the entire global energy sector, with a recent focus on curbing car ...
recommends using the term "light tight oil" for oil produced from shales or other very low permeability formations, while the World Energy Resources 2013 report by the
World Energy Council
The World Energy Council is a global forum for thought-leadership and tangible engagement with headquarters in London. Its mission is 'To promote the sustainable supply and use of energy for the greatest benefit of all people'.
The idea for the fo ...
uses the terms "tight oil" and "shale-hosted oil".
In May 2013 the International Energy Agency
The International Energy Agency (IEA) is a Paris-based autonomous intergovernmental organisation, established in 1974, that provides policy recommendations, analysis and data on the entire global energy sector, with a recent focus on curbing car ...
in its ''Medium-Term Oil Market Report'' (MTOMR) said that the North American oil production surge led by unconventional oils - US light tight oil (LTO) and Canadian oil sands
Oil sands, tar sands, crude bitumen, or bituminous sands, are a type of unconventional petroleum deposit. Oil sands are either loose sands or partially consolidated sandstone containing a naturally occurring mixture of sand, clay, and wate ...
- had produced a global supply shock that would reshape the way oil is transported, stored, refined and marketed.
Inventory and examples
Tight oil formations include the Bakken Shale
The Bakken Formation () is a rock unit from the Late Devonian to Early Mississippian age occupying about of the subsurface of the Williston Basin, underlying parts of Montana, North Dakota, Saskatchewan and Manitoba. The formation was i ...
, the Niobrara Formation
The Niobrara Formation , also called the Niobrara Chalk, is a geologic formation in North America that was deposited between 87 and 82 million years ago during the Coniacian, Santonian, and Campanian stages of the Late Cretaceous. It is com ...
, Barnett Shale, and the Eagle Ford Shale in the United States, R'Mah Formation in Syria
Syria ( ar, سُورِيَا or سُورِيَة, translit=Sūriyā), officially the Syrian Arab Republic ( ar, الجمهورية العربية السورية, al-Jumhūrīyah al-ʻArabīyah as-Sūrīyah), is a Western Asian country loc ...
, Sargelu Formation in the northern Persian Gulf
The Persian Gulf ( fa, خلیج فارس, translit=xalij-e fârs, lit=Gulf of Fars, ), sometimes called the ( ar, اَلْخَلِيْجُ ٱلْعَرَبِيُّ, Al-Khalīj al-ˁArabī), is a mediterranean sea in Western Asia. The bo ...
region, Athel Formation in Oman
Oman ( ; ar, عُمَان ' ), officially the Sultanate of Oman ( ar, سلْطنةُ عُمان ), is an Arabian country located in southwestern Asia. It is situated on the southeastern coast of the Arabian Peninsula, and spans the mouth of ...
, Bazhenov Formation
The Bazhenov Formation or Bazhenov Shale is a geological stratum in the West Siberian basin. It was formed from sediment deposited in a deep-water sea in Tithonian–early Berriasian time. The sea covered more than one million square kilometer ...
and Achimov Formation of West Siberia
Western Siberia or West Siberia (russian: Западная Сибирь, Zapadnaya Sibir'; kk, Батыс Сібір) is a part of the larger region of Siberia that is mostly located in the Russian Federation. It lies between the Ural region an ...
in Russia
Russia (, , ), or the Russian Federation, is a transcontinental country spanning Eastern Europe and Northern Asia. It is the largest country in the world, with its internationally recognised territory covering , and encompassing one-ei ...
, Arckaringa Basin
The Arckaringa Basin is an endorheic basin in Australia. It is in size and is located in South Australia.
The basin surrounds the town of Coober Pedy in northern South Australia. It located in the north of the Gawler Craton, Gawler Block.
Str ...
in Australia
Australia, officially the Commonwealth of Australia, is a sovereign country comprising the mainland of the Australian continent, the island of Tasmania, and numerous smaller islands. With an area of , Australia is the largest country by ...
, Chicontepec Formation in Mexico
Mexico (Spanish language, Spanish: México), officially the United Mexican States, is a List of sovereign states, country in the southern portion of North America. It is borders of Mexico, bordered to the north by the United States; to the so ...
,[ and the Vaca Muerta oil field in ]Argentina
Argentina (), officially the Argentine Republic ( es, link=no, República Argentina), is a country in the southern half of South America. Argentina covers an area of , making it the List of South American countries by area, second-largest ...
. In June 2013 the U.S. Energy Information Administration
The U.S. Energy Information Administration (EIA) is a principal agency of the U.S. Federal Statistical System responsible for collecting, analyzing, and disseminating energy information to promote sound policymaking, efficient markets, and publ ...
published a global inventory of estimated recoverable tight oil and tight gas resources in shale formations, "Technically Recoverable Shale Oil and Shale Gas Resources: An Assessment of 137 Shale Formations in 41 Countries Outside the United States." The inventory is incomplete due to exclusion of tight oil and gas from sources other than shale such as sandstone or carbonates, formations underlying the large oil fields located in the Middle East and the Caspian region, off shore formations, or about which there is little information. Amounts include only high quality prospects which are likely to be developed.
In 2012, at least 4,000 new producing shale oil (tight oil) wells were brought online in the United States. By comparison, the number of new producing oil and gas wells (both conventional and unconventional) completed in 2012 globally outside the United States and Canada is less than 4,000.["The Shale Oil Boom: a US Phenomenon"]
by Leonardo Maugeri, Harvard University, Geopolitics of Energy Project, Belfer Center for Science and International Affairs
The Robert and Renée Belfer Center for Science and International Affairs, also known as the Belfer Center, is a research center located within the Harvard Kennedy School at Harvard University, in the United States. From 2017 until his death in O ...
, Discussion Paper 2013-05
Characteristics
Tight oil shale formations are heterogeneous and vary widely over relatively short distances. Tight oil reservoirs subjected to fracking can be divided into four different groups. Type I has little matrix porosity and permeability – leading to fractures dominating both storage capacity and fluid flow pathways. Type II has low matrix porosity and permeability, but here the matrix provides storage capacity while fractures provide fluid-flow paths. Type III are microporous reservoirs with high matrix porosity but low matrix permeability, thus giving induced fractures dominance in fluid-flow paths. Type IV is macroporous reservoirs with high matrix porosity and permeability, thus the matrix provides both storage capacity and flow paths while fractures only enhance permeability.
Even in a single horizontal drill hole, the amount recovered may vary, as may recovery within a field or even between adjacent wells. This makes evaluation of plays and decisions regarding the profitability of wells on a particular lease difficult. Production of oil from tight formations requires at least 15 to 20 percent natural gas in the reservoir pore space to drive the oil toward the borehole; tight reservoirs which contain only oil cannot be economically produced. Formations which formed under marine conditions contain less clay and are more brittle, and thus more suitable for fracking
Fracking (also known as hydraulic fracturing, hydrofracturing, or hydrofracking) is a well stimulation technique involving the fracturing of bedrock formations by a pressurized liquid. The process involves the high-pressure injection of "frac ...
than formations formed in fresh water which may contain more clay. Formations with more quartz and carbonate are more brittle.
The natural gas and other volatiles in LTO make it more hazardous to handle, store, and transport. This was an aggravating factor in the series of fatal explosions after the Lac-Mégantic derailment.
Exploitation
Prerequisites for exploitation include being able to obtain rights to drill, easier in the United States and Canada where private owners of subsurface rights are motivated to enter into leases; the availability of expertise and financing, easier in the United States and Canada where there are many independent operators and supporting contractors with critical expertise and suitable drilling rigs; infrastructure to gather and transport oil; and water resources for use in
hydraulic fracturing.
Analysts expect that $150 billion will be spent on further developing North American tight oil fields in 2015. The large increase in tight oil production is one of the reasons behind the price drop in late 2014.
Outside the United States and Canada, development of shale oil (tight oil) resources may be limited by the lack of available drilling rigs: 2/3 of the world's active drill rigs are in the US and Canada, and rigs elsewhere are less likely to be equipped for horizontal drilling. Drilling intensity may be another constraint, as tight-oil development requires far more completed wells than does conventional oil. Leonardo Maugeri considers this will be "an insurmountable environmental hurdle in Europe".[
Detailed studies on production behaviour in prolific shale plays were light tight oil is produced have shown that the average monthly initial production of a tight oil well is around 500 barrels/day, which yields an estimated ultimate recovery in the range 150-290 thousand barrels.] As a consequence, exploitation of tight oil tends to be drilling intensive with many new wells needed to ramp up and maintain production over time.
Size of tight oil resources
US EIA estimated technically recoverable tight oil in shale
Following are estimates of technically recoverable volumes of tight oil associated with shale formations, made by the US Energy Information Administration in 2013. Not all oil which is technically recoverable may be economically recoverable at current or anticipated prices.
#Kingdom of Bahrain: 80 billion barrels
#Russia: 75 billion barrels
#United States: 78 billion barrels
#China: 32 billion barrels
#Argentina: 27 billion barrels
#Libya: 26 billion barrels
#Venezuela: 13 billion barrels
#Mexico: 13 billion barrels
#Pakistan: 9 billion barrels
#Canada: 9 billion barrels
#Indonesia: 8 billion barrels
World Total: 335 to 345 billion barrels
Other estimates
Australia: A private oil company announced in 2013 that it had discovered tight oil in shale of the Arckaringa Basin
The Arckaringa Basin is an endorheic basin in Australia. It is in size and is located in South Australia.
The basin surrounds the town of Coober Pedy in northern South Australia. It located in the north of the Gawler Craton, Gawler Block.
Str ...
, estimated at 3.5 to 223 billion barrels.
Production
In September 2018, the U.S. Energy Information Administration
The U.S. Energy Information Administration (EIA) is a principal agency of the U.S. Federal Statistical System responsible for collecting, analyzing, and disseminating energy information to promote sound policymaking, efficient markets, and publ ...
projected October tight oil production in the U.S. at 7.6 million barrels per day.
The volume of oil production on tight oil formations in the US depends significantly on the dynamics of the WTI oil price. About six months after the price change, drilling activity changes, and with it the volume of production. These changes and their expectations are so significant that they themselves affect the price of oil and hence the volume of production in the future. These regularities are described in mathematical language by a differential extraction equation with a retarded argument.
Tight oil differs from conventional oil, as both investment and production dynamics of tight oil is significantly faster than conventional counterparts. This may reduce risks associated with locked-in capital and also contributed to a more flexible production that reduces oil price volatility. Unexpectedly, this faster dynamics can also entail lesser carbon lock-in effects and stranded asset risks with implications for climate policies.
See also
* Unconventional (oil & gas) reservoir
Unconventional (oil & gas) reservoirs, or unconventional resources (resource plays) are accumulations where oil & gas phases are tightly bound to the rock fabric by strong capillary forces, requiring specialised measures for evaluation and extr ...
* Tight gas
* Shale gas
* Shale oil extraction
References
External links
Shale oil and tight oil
The Shale Oil Boom: a US Phenomenon
by Leonardo Maugeri, Harvard University, Geopolitics of Energy Project, Belfer Center for Science and International Affairs
The Robert and Renée Belfer Center for Science and International Affairs, also known as the Belfer Center, is a research center located within the Harvard Kennedy School at Harvard University, in the United States. From 2017 until his death in O ...
, Discussion Paper 2013-05
{{Petroleum industry, collapsed
Unconventional oil