Shale oil

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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 can be used immediately as a fuel or upgraded to meet refinery feedstock specifications by adding hydrogen and removing impurities such as sulfur and nitrogen. The refined products can be used for the same purposes as those derived from crude oil.

Contents

The term "shale oil" is also used for crude oil produced from shales of other unconventional, very low permeability formations. However, to reduce the risk of confusion of shale oil produced from oil shale with crude oil in oil-bearing shales, the term "tight oil" is preferred for the latter. [1] The International Energy Agency recommends to use the term "light tight oil" and World Energy Resources 2013 report by the World Energy Council uses the term "tight oil" for crude oil in oil-bearing shales. [2] [3]

History

Three West Lothian shale mounds, evidence of the early paraffin oil industry in the 19th century Scotland West Lothian shale bing, Scotland.JPG
Three West Lothian shale mounds, evidence of the early paraffin oil industry in the 19th century Scotland

Oil shale was one of the first sources of mineral oil used by humans. [4] In the 10th century, the Arabic physician Masawaih al-Mardini (Mesue the Younger) first described a method of extracting oil from "some kind of bituminous shale". [5] It was also reported to have been used in Switzerland and Austria in the early 14th century. [6] In 1596, the personal physician of Frederick I, Duke of Württemberg wrote of its healing properties. [7] Shale oil was used to light the streets of Modena, Italy at the turn of the 18th century. [7] The British Crown granted a patent in 1694 to three persons who had "found a way to extract and make great quantities of pitch, tarr and oyle out of a sort of stone." [7] [8] [9] Later sold as Betton's British Oil, the distilled product was said to have been "tried by diverse persons in Aches and Pains with much benefit." [10] Modern shale oil extraction industries were established in France during the 1830s and in Scotland during the 1840s. [11] The oil was used as fuel, as a lubricant and lamp oil; the Industrial Revolution had created additional demand for lighting. It served as a substitute for the increasingly scarce and expensive whale oil. [7] [12] [13]

During the late 19th century, shale-oil extraction plants were built in Australia, Brazil and the United States. China, Estonia, New Zealand, South Africa, Spain, Sweden and Switzerland produced shale oil in the early 20th century. The discovery of crude oil in the Middle East during mid-century brought most of these industries to a halt, although Estonia and Northeast China maintained their extraction industries into the early 21st century. [11] [14] [15] In response to rising petroleum prices at the turn of the 21st century, extraction operations have commenced, been explored, or been renewed in the United States, China, Australia and Jordan. [15]

Extraction process

Shale oil is extracted by pyrolysis, hydrogenation, or thermal dissolution of oil shale. [16] [17] The pyrolysis of the rock is performed in a retort, situated either above ground or within the rock formation itself. As of 2008, most oil shale industries perform the shale oil extraction process after the rock is mined, crushed and transported to a retorting facility, although several experimental technologies perform the process in place ( in-situ ). The temperature at which the kerogen decomposes into usable hydrocarbons varies with the time-scale of the process; in the above-ground retorting process decomposition begins at 300 °C (570 °F), but proceeds more rapidly and completely at higher temperatures. Decomposition takes place most quickly at a temperature between 480 and 520 °C (900 and 970 °F). [16]

Hydrogenation and thermal dissolution (reactive fluid processes) extract the oil using hydrogen donors, solvents, or a combination of these. Thermal dissolution involves the application of solvents at elevated temperatures and pressures, increasing oil output by cracking the dissolved organic matter. Different methods produce shale oil with different properties. [17] [18] [19] [20]

A critical measure of the viability of extraction of shale oil lies in the ratio of the energy produced by the oil shale to the energy used in its mining and processing, a ratio known as "Energy Returned on Energy Invested" (EROEI). An EROEI of 2 (or 2:1 ratio) would mean that to produce 2 barrels of actual oil the equivalent in energy of 1 barrel of oil has to be burnt/consumed. A 1984 study estimated the EROEI of the various known oil-shale deposits as varying between 0.7 and 13.3. [21] More recent studies estimates the EROEI of oil shales to be 1–2:1 or 2–16:1 – depending on whether self-energy is counted as a cost or internal energy is excluded and only purchased energy is counted as input. [22] Royal Dutch Shell reported an EROEI of three to four in 2006 on its in situ development in the "Mahogany Research Project." [23] [24]

The amount of oil that can be recovered during retorting varies with the oil shale and the technology used. [15] About one sixth of the oil shales in the Green River Formation have a relatively high yield of 25 to 100 US gallons (95 to 379 L; 21 to 83 imp gal) of shale oil per ton of oil shale; about one third yield from 10 to 25 US gallons (38 to 95 L; 8.3 to 20.8 imp gal) per ton. (Ten US gal/ton is approximately 3.4 tons of oil per 100 tons of shale.) About half of the oil shales in the Green River Formation yield less than 10 US gal/ton. [25]

The major global shale oil producers have published their yields for their commercial operations. Fushun Mining Group reports producing 300,000 tons per year of shale oil from 6.6 million tons of shale, a yield of 4.5% by weight. [26] VKG Oil claims to produce 250,000 tons of oil per year from 2 million tons of shale, a yield of 13%. [27] Petrobras produces in their Petrosix plant 550 tons of oil per day from 6,200 tons of shale, a yield of 9%. [28]

Properties

The properties of raw shale oil vary depending on the composition of the parent oil shale and the extraction technology used. [29] Like conventional oil, shale oil is a complex mixture of hydrocarbons, and is characterized according to the bulk properties of the oil. It usually contains large quantities of olefinic and aromatic hydrocarbons. It can also contain significant quantities of heteroatoms. A typical shale oil composition includes 0.5–1% of oxygen, 1.5–2% of nitrogen and 0.15–1% of sulfur; some deposits contain more heteroatoms than others. Mineral particles and metals are often present as well. [30] [31] Generally, the oil is less fluid than crude oil, becoming pourable at temperatures between 24 and 27 °C (75 and 81 °F), while conventional crude oil is pourable at temperatures between −60 and 30 °C (−76 and 86 °F); this property affects shale oil's ability to be transported in existing oil pipelines. [30] [32] [33]

Shale oil contains polycyclic aromatic hydrocarbons, which are carcinogenic. The US EPA has concluded that raw shale oil has a mild carcinogenic potential, comparable to some intermediate petroleum refinery products, while upgraded shale oil has lower carcinogenic potential, as most of the polycyclic aromatics are believed to have been broken down by hydrogenation. [34] The World Health Organization classifies shale oil as a Group 1 carcinogen to humans. [35]

Upgrading

Although raw shale oil can be immediately burnt as a fuel oil, many of its applications require that it be upgraded. The differing properties of the raw oils call for correspondingly various pre-treatments before it can be sent to a conventional oil refinery. [36]

Particulates in the raw oil clog downstream processes; sulfur and nitrogen create air pollution. Sulfur and nitrogen, along with the arsenic and iron that may be present, also destroy the catalysts used in refining. [37] [38] Olefins form insoluble sediments and cause instability. The oxygen within the oil, present at higher levels than in crude oil, lends itself to the formation of destructive free radicals. [31] Hydrodesulfurization and hydrodenitrogenation can address these problems and result in a product comparable to benchmark crude oil. [30] [31] [39] [40] Phenols can be first removed by water extraction. [40] Upgrading shale oil into transport fuels requires adjusting hydrogen–carbon ratios by adding hydrogen (hydrocracking) or removing carbon (coking). [39] [40]

Shale oil produced by some technologies, such as the Kiviter process, can be used without further upgrading as an oil constituent and as a source of phenolic compounds. Distillate oils from the Kiviter process can also be used as diluents for petroleum-originated heavy oils and as an adhesive-enhancing additive in bituminous materials such as asphalt. [40]

Uses

Before World War II, most shale oil was upgraded for use as transport fuels. Afterwards, it was used as a raw material for chemical intermediates, pure chemicals and industrial resins, and as a railroad wood preservative. As of 2008, it is primarily used as a heating oil and marine fuel, and to a lesser extent in the production of various chemicals. [36]

Shale oil's concentration of high-boiling point compounds is suited for the production of middle distillates such as kerosene, jet fuel and diesel fuel. [31] [41] [42] Additional cracking can create the lighter hydrocarbons used in gasoline. [31] [43]

"Pale sulfonated shale oil" (PSSO), a sulfonated and ammonia-neutralized variant named "Ichthammol" (chemical name: Ammonium bituminosulfonate) is still in application today. [44]

Reserves and production

Global technically recoverable oil shale reserves have recently been estimated at 2.8 to 3.3 trillion barrels (450×10^9 to 520×10^9 m3) of shale oil, with the largest reserves in the United States, which is thought to have 1.5–2.6 trillion barrels (240×10^9–410×10^9 m3). [14] [41] [45] [46] Worldwide production of shale oil was estimated at 17,700 barrels per day (2,810 m3/d) in 2008. The leading producers were China (7,600 barrels per day (1,210 m3/d)), Estonia (6,300 barrels per day (1,000 m3/d)), and Brazil (3,800 barrels per day (600 m3/d)). [14]

The production of shale oil has been hindered because of technical difficulties and costs. [47] In March 2011, the United States Bureau of Land Management called into question proposals for commercial operations in Colorado, Utah and Wyoming, stating that "(t)here are no economically viable ways yet known to extract and process oil shale for commercial purposes". [48] The US Energy Information Administration sometimes uses the phrase "shale (tight) oil" to refer to tight oil, "crude oil ... produced directly from tight oil resources". In 2021, the US produced 7.23 million barrels of such tight oil each day, equal to about 64% of total U.S. crude oil production. [49] The IEA also occasionally calls tight oil "shale oil", [50] but classifies any products from oil shale with solid fuels. [51]

See also

Related Research Articles

<span class="mw-page-title-main">Oil shale</span> Organic-rich fine-grained sedimentary rock containing kerogen

Oil shale is an organic-rich fine-grained sedimentary rock containing kerogen from which liquid hydrocarbons can be produced. In addition to kerogen, general composition of oil shales constitutes inorganic substance and bitumens. Based on their deposition environment, oil shales are classified as marine, lacustrine and terrestrial oil shales. Oil shales differ from oil-bearing shales, shale deposits that contain petroleum that is sometimes produced from drilled wells. Examples of oil-bearing shales are the Bakken Formation, Pierre Shale, Niobrara Formation, and Eagle Ford Formation. Accordingly, shale oil produced from oil shale should not be confused with tight oil, which is also frequently called shale oil.

<span class="mw-page-title-main">Peak oil</span> Point in time when the maximum rate of petroleum extraction is reached

Peak oil is the point in time when the maximum rate of global oil production is reached, after which production will begin an irreversible decline. It is related to the distinct concept of oil depletion; while global petroleum reserves are finite, the limiting factor is not whether the oil exists but whether it can be extracted economically at a given price. A secular decline in oil extraction could be caused both by depletion of accessible reserves and by reductions in demand that reduce the price relative to the cost of extraction, as might be induced to reduce carbon emissions or from demand destruction triggered by persistently high oil prices.

Coal liquefaction is a process of converting coal into liquid hydrocarbons: liquid fuels and petrochemicals. This process is often known as "Coal to X" or "Carbon to X", where X can be many different hydrocarbon-based products. However, the most common process chain is "Coal to Liquid Fuels" (CTL).

<span class="mw-page-title-main">Synthetic fuel</span> Fuel from carbon monoxide and hydrogen

Synthetic fuel or synfuel is a liquid fuel, or sometimes gaseous fuel, obtained from syngas, a mixture of carbon monoxide and hydrogen, in which the syngas was derived from gasification of solid feedstocks such as coal or biomass or by reforming of natural gas.

<span class="mw-page-title-main">Karrick process</span>

The Karrick process is a low-temperature carbonization (LTC) and pyrolysis process of carbonaceous materials. Although primarily meant for coal carbonization, it also could be used for processing of oil shale, lignite or any carbonaceous materials. These are heated at 450 °C (800 °F) to 700 °C (1,300 °F) in the absence of air to distill out synthetic fuels–unconventional oil and syngas. It could be used for a coal liquefaction as also for a semi-coke production. The process was the work of oil shale technologist Lewis Cass Karrick at the United States Bureau of Mines in the 1920s.

Petrosix is the world's largest surface oil shale pyrolysis retort with an 11 metres (36 ft) diameter vertical shaft kiln, operational since 1992. It is located in São Mateus do Sul, Brazil, and it is owned and operated by the Brazil energy company Petrobras. Petrosix means also the Petrosix process, an externally generated hot gas technology of shale oil extraction. The technology is tailored to Irati oil shale formation, a Permian formation of the Paraná Basin.

<span class="mw-page-title-main">Oil shale geology</span> Branch of geology

Oil shale geology is a branch of geologic sciences which studies the formation and composition of oil shales–fine-grained sedimentary rocks containing significant amounts of kerogen, and belonging to the group of sapropel fuels. Oil shale formation takes place in a number of depositional settings and has considerable compositional variation. Oil shales can be classified by their composition or by their depositional environment. Much of the organic matter in oil shales is of algal origin, but may also include remains of vascular land plants. Three major type of organic matter (macerals) in oil shale are telalginite, lamalginite, and bituminite. Some oil shale deposits also contain metals which include vanadium, zinc, copper, and uranium.

<span class="mw-page-title-main">Oil shale industry</span> Resource extraction industry

The oil shale industry is an industry of mining and processing of oil shale—a fine-grained sedimentary rock, containing significant amounts of kerogen, from which liquid hydrocarbons can be manufactured. The industry has developed in Brazil, China, Estonia and to some extent in Germany and Russia. Several other countries are currently conducting research on their oil shale reserves and production methods to improve efficiency and recovery. Estonia accounted for about 70% of the world's oil shale production in a study published in 2005.

<span class="mw-page-title-main">Shale oil extraction</span> Process for extracting oil from oil shale

Shale oil extraction is an industrial process for unconventional oil production. This process converts kerogen in oil shale into shale oil by pyrolysis, hydrogenation, or thermal dissolution. The resultant shale oil is used as fuel oil or upgraded to meet refinery feedstock specifications by adding hydrogen and removing sulfur and nitrogen impurities.

Oil shale economics deals with the economic feasibility of oil shale extraction and processing. Although usually oil shale economics is understood as shale oil extraction economics, the wider approach evaluates usage of oil shale as a whole, including for the oil-shale-fired power generation and production of by-products during retorting or shale oil upgrading processes.

<span class="mw-page-title-main">Environmental impact of the oil shale industry</span>

Environmental impact of the oil shale industry includes the consideration of issues such as land use, waste management, and water and air pollution caused by the extraction and processing of oil shale. Surface mining of oil shale deposits causes the usual environmental impacts of open-pit mining. In addition, the combustion and thermal processing generate waste material, which must be disposed of, and harmful atmospheric emissions, including carbon dioxide, a major greenhouse gas. Experimental in-situ conversion processes and carbon capture and storage technologies may reduce some of these concerns in future, but may raise others, such as the pollution of groundwater.

<span class="mw-page-title-main">History of the oil shale industry</span> Timeline of the production of oil shale

The history of the oil shale industry started in ancient times. The modern industrial use of oil shale for oil extraction dates to the mid-19th century and started growing just before World War I because of the mass production of automobiles and trucks and the supposed shortage of gasoline for transportation needs. Between the World Wars oil shale projects were begun in several countries.

Oil shale gas is a synthetic non-condensable gas mixture (syngas) produced by oil shale thermal processing (pyrolysis). Although often referred to as shale gas, it differs from the natural gas produced from shale, which is also known as shale gas.

Oil shale in China is an important source of unconventional oil. A total Chinese oil shale resource amounts of 720 billion tonnes, located in 80 deposits of 47 oil shale basins. This is equal to 48 billion tonnes of shale oil. At the same time there are speculations that the actual resource may even exceed the oil shale resource of the United States.

<span class="mw-page-title-main">Galoter process</span> Shale oil extraction technology

The Galoter process is a shale oil extraction technology for the production of shale oil, a type of synthetic crude oil. In this process, the oil shale is decomposed into shale oil, oil shale gas, and spent residue. Decomposition is caused by mixing raw oil shale with hot oil shale ash generated by the combustion of carbonaceous residue (semi-coke) in the spent residue. The process was developed in the 1950s, and it is used commercially for shale oil production in Estonia. There are projects for further development of this technology and expansion of its usage, e.g., in Jordan and the USA.

The Alberta Taciuk process is an above-ground dry thermal retorting technology for extracting oil from oil sands, oil shale and other organics-bearing materials, including oil contaminated soils, sludges and wastes. The technology is named after its inventor William Taciuk and the Alberta Oil Sands Technology and Research Authority.

In the United States, synthetic fuels are of increasing importance due to the price of crude oil, and geopolitical and economic considerations.

The Nevada–Texas–Utah retort process was an above-ground shale oil extraction technology to produce shale oil, a type of synthetic crude oil. It heated oil shale in a sealed vessel (retort) causing its decomposition into shale oil, oil shale gas and spent residue. The process was developed in the 1920s and used for shale oil production in the United States and in Australia. The process was simple to operate; however, it was ceased from the operation because of a small capacity and labor extensiveness.

The Union process was an above ground shale oil extraction technology for production of shale oil, a type of synthetic crude oil. The process used a vertical retort where heating causes decomposition of oil shale into shale oil, oil shale gas and spent residue. The particularity of this process is that oil shale in the retort moves from the bottom upward to the top, countercurrent to the descending hot gases, by a mechanism known as a rock pump. The process technology was invented by the American oil company Unocal Corporation in late 1940s and was developed through several decades. The largest oil shale retort ever built was the Union B type retort.

The history of the oil shale industry in the United States goes back to the 1850s; it dates back farther as a major enterprise than the petroleum industry. But although the United States contains the world's largest known resource of oil shale, the US has not been a significant producer of shale oil since 1861. There were three major past attempts to establish an American oil shale industry: the 1850s; in the years during and after World War I; and in the 1970s and early 1980s. Each time, the oil shale industry failed because of competition from cheaper petroleum.

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  46. ↑ "NPR's National Strategic Unconventional Resource Model" (PDF). United States Department of Energy. April 2006. Retrieved 9 July 2007.{{cite journal}}: Cite journal requires |journal= (help)
  47. ↑ Kraushaar, Jack P., and Robert A. Ristinen. Energy and the Environment-2nd ed. New York, NY: Wiley & Sons Inc., 2006. 54–56.
  48. ↑ Bureau of Land Management (14 April 2011). "Notice of Intent To Prepare a Programmatic Environmental Impact Statement (EIS) and Possible Land Use Plan Amendments for Allocation of Oil Shale and Tar Sands Resources on Lands Administered by the Bureau of Land Management in Colorado, Utah and Wyoming" (PDF). Federal Register. 76 (72): 21003–21005. Retrieved 9 October 2011.
  49. ↑ "FAQS: How much shale (tight) oil is produced in the United States?". 4 October 2022. Retrieved 7 October 2022.
  50. ↑ International Energy Agency (IEA) (26 October 2022). "US shale oil production in the Stated Policies Scenario, 2005-2030" . Retrieved 1 November 2022.
  51. ↑ International Energy Agency (IEA) (26 October 2022). "Total energy supply outlook by fuel and scenario, 2000-2040" . Retrieved 1 November 2022.
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