Instruct: Given a question, retrieve relevant documents that answer the question.
Query: How is oil shale made?
Oil shale is an organic-rich fine-grained sedimentary rock containing kerogen (a solid mixture of organic chemical compounds) from which liquid hydrocarbons can be produced, called shale oil (not to be confused with tight oil—crude oil occurring naturally in shales). Shale oil is a substitute for conventional crude oil; however, extracting shale oil from oil shale is more costly than the production of conventional crude oil both financially and in terms of its environmental impact.[1] Deposits of oil shale occur around the world, including major deposits in the United States. A 2016 estimate of global deposits set the total world resources of oil shale equivalent of 6.05 trillion barrels (962billion cubic metres) of oil in place.[2]
Since 1965, oil shale usage in Fushun started to decline. With the discovery of Daqing oilfield in the 1960s, the shale oil production declined and Sinopec, an operator of shale oil production these times, shut down its oil shale operations in the beginning of the 1990s. At the same time, the Fushun Oil Shale Retorting Plant was established as a part of the Fushun Mining Group. It started production in 1992. In 2005, China became the largest shale oil producer in the world. At the same year, China National Oil Shale Association was established in Fushun.
Oil shale () is a strategic energy resource that constitutes about 4% of Estonia's gross domestic product. The oil shale industry in Estonia is one of the most developed in the world. In 2012, the country's oil shale industry employed 6,500 people – about 1% of the national workforce. Of all the oil shale fired power stations in the world, the two largest are in this country. In 2012, 70% of mined oil shale was used for electricity generation, accounting for about 85% of Estonia's total electricity production. A smaller proportion of the mined oil shale is used to produce shale oil, a type of synthetic oil extracted from shale by pyrolysis, which is sufficient to keep Estonia as the second largest shale oil producer in the world after China. In addition, oil shale and its products are used in Estonia for district heating and as a feedstock material for the cement industry.
Tight oil (also known as shale oil, shale-hosted oil or light tight oil, abbreviated LTO) is light crude oil contained in petroleum-bearing formations of low permeability, often shale or tight sandstone. Economic production from tight oil formations requires the same hydraulic fracturing 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, which is shale rich in kerogen, or shale oil, which is oil produced from oil shales. Therefore, the International Energy Agency 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 uses the terms "tight oil" and "shale-hosted oil".
The term "shale oil" is also used for crude oil produced from shales of other 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. 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.
The Galoter process (also known as TSK, UTT, or SHC; its newest modifications are called Enefit and Petroter) is a shale oil extraction technology for a 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. A decomposition is caused by mixing raw oil shale with a hot oil shale ash, generated by combustion of carbonaceous residue (semi-coke) in the spent residue. The process was developed in 1950s and it is used commercially for the shale oil production in Estonia. There are projects for further development of this technology and for expansion of its usage, e.g. in Jordan and USA.
In Austria, oil shale was used in 1840–1882 for production of asphalt mastic, naphtha and asphalt tar. In Sweden, the first attempt to extract oil from alum shale was made in 1864. Shale oil production started in the 1890s and lasted few years. In Brazil, oil shale was first exploited in 1884 in Bahia. In 1900 shale oil extraction industry was initiated also in New Zealand.
As a heat carrier, LLNL HRS process uses spent oil shale. Raw oil shale and spent oil shale are mixed in the fluidized bed mixer. The use of fluidized bed mixer results in better mixture, which in turn increases the mean quantity of oil yield and oil shale throughput. From the fluidized bed mixer oil shale moves downward to the packed-bed pyrolyzer. The heat is transferred from the heated spent oil shale to the raw oil shale causing pyrolysis. As a result, oil shale decomposes to shale oil vapors, oil shale gas and spent oil shale. Oil vapors are collected from the pyrolyzer. The spent oil shale, still including residual carbon (char), by the air pneumatic lift pipe to the delayed-fall combustor where it is combusted to heat the process. The delayed-fall combustor used in this process gives greater control over the combustion process as compared to a lift pipe combustor. From the delayed-fall combustor the oil shale ash and spent shale falls into a fluidized bed classifier where the finest parts of solids are removed and hot spent shale is forwarded to the fluidized bed mixer.
Oil shale deposits formed in the shallow seas of continental shelves generally are much thinner than large lake basin deposits. These are typically a few meters thick and are spread over very large areas, extending up to thousands of square kilometers. Of the three lithologic types of oil shales, siliceous oil shales are most commonly found in such environments. These oil shales are not as organically rich as lake-deposited oil shales, and generally do not contain more than 30 gallons of extractable oil per ton of oil shale. Oil shales deposited in lagoonal or small lake environments are rarely extensive and are often associated with coal-bearing rocks. These oil shales can have high yields– as much as 40 gallons per ton (166 l/t) of oil shale. However, due to their small areal extent, they are considered unlikely candidates for commercial exploitation.
The year 1916 is considered the beginning of the Estonian oil shale industry. when a group of geologists, led by Nikolay Pogrebov, was sent to Estonia to organise the mining of oil shale and its transportation to Saint Petersburg (then known as Petrograd). In June 1916, the first tonnes of oil shale were mined at Pavandu and delivered to Saint Petersburg Polytechnical University for large-scale experiments. In 1917, Russian paleontologist Mikhail Zalessky named kukersite oil shale after the Kukruse settlement. Continuous mining activities started shortly after. Initially, oil shale was used primarily in the cement industry, for firing in locomotive furnaces, and as a household fuel, followed by shale oil and power production. As of 1925, all locomotives in Estonia were powered by oil shale. The first experimental oil shale processing retorts were built in 1921, using the method developed by Julius Pintsch AG. In 1924, the Tallinn Power Plant was the first power plant in the world to employ oil shale as its primary fuel. In 1939 Estonia mined 1.453 million tonnes of oil shale and produced 181,000 tonnes of shale oil, including 22,500 tonnes of oil that were suitable gasoline equivalents. Almost half of Estonian produced shale oil was exported accounting for 8% of country's total export.
The first attempts to exploit the Green River Formation deposit was made by establishment of The Oil Shale Mining Company in 1916. In 1917, they erected the first commercial retort at the head of Dry Creek, near De Beque, Colorado. However, also these attempts were unsuccessful and by 1926 the company had lost its property. In addition, companies like Cities Service, Standard Oil of California, Texaco and Union started their oil shale operations in 1918–1920. In 1915–1920 about 200 companies were established to exploit oil shale and at least 25 shale oil retorting processes reached to the pilot-plant stage.
The process was developed to combine the shale oil production with production of sodium bicarbonate, sodium carbonate, and aluminum from nahcolite and dawsonite, occurring in oil shales of the Piceance Basin. In this process, the nahcolite is recovered from the raw oil shale by crushing it to lumps smaller than . As a result, most of the nahcolite in the oil shale becomes a fine powder what could screened out. Screened oil shale lumps are further crushed to particles smaller than . Oil shale particles are further processed in a horizontal segmented doughnut-shaped traveling-grate retort in the direct or indirect heating mode. The retort was originally designed by Davy McKee Corporation for iron ore pelletizing and it also known as the Dravo retort. In the direct retort, oil shale moves past ducts through which are provided hot inert gas for heating the raw oil shale, air for combustion of carbon residue (char or semi-coke) in the spent oil shale, and cold inert gas for cooling the spent oil shale. The oil pyrolysis takes place in the heating section. To minimize solubility of aluminium compounds in the oil shale, the heat control is a crucial factor. Necessary heat for pyrolysis is generated in the carbon recovery section by combustion of carbon residue (char or semi-coke) remained in the spent oil shale. While blowing inert gases through the spent oil shale, the spent oil shale is cooled and gases are heated to cause pyrolysis. The indirect mode is similar; the difference is that combustion of carbonaceous residue takes place in separate vessel. The last section is for discharging of oil shale ash. Aluminium oxide and sodium carbonate are recovered from calcined dawsonite and calcined nahcolite in the oil shale ash.
The oldest and the most common extraction method involves pyrolysis (also known as "retorting" or destructive distillation). In this process, oil shale is heated in the absence of oxygen until its kerogen decomposes into condensable shale oil vapors and non-condensable combustible oil shale gas. Oil vapors and oil shale gas are then collected and cooled, causing the shale oil to condense. In addition, oil shale processing produces spent oil shale, which is a solid residue. Spent shale consists of inorganic compounds (minerals) and char—a carbonaceous residue formed from kerogen. Burning the char off the spent shale produces oil shale ash. Spent shale and shale ash can be used as ingredients in cement or brick manufacture. The composition of the oil shale may lend added value to the extraction process through the recovery of by-products, including ammonia, sulfur, aromatic compounds, pitch, asphalt, and waxes.
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 whole, including for the oil-shale-fired power generation and production of by-products during retorting or shale oil upgrading processes.[1]
During the 1850s, large-scale works were undertaken in Estonia to transform excessively wet land into land suitable for agriculture; this included the digging of drainage ditches. In the process, previously unknown layers of oil shale were discovered in several locations. In the years 1850–1857, the territory of Estonia was explored by the Baltic German geologist Carl Friedrich Schmidt who studied these findings of oil shale. Russian chemist Aleksandr Shamarin, who at the end of the 1860s had studied the composition and properties of oil shale originating from the Kukruse area, concluded it made sense to use oil shale for the production of gas and as a solid fuel. However, he considered shale oil production unprofitable. During the remainder of the 19th century oil shale was used locally as a low-grade fuel only. For example, in the 1870s, Robert von Toll, landlord of the Kukruse Manor, started to use oil shale as a fuel for the manor's distillery. There were failed attempts to use graptolitic argillite as fertilizer in the 19th century. In the beginning of the 20th century, geologist and engineer Carl August von Mickwitz studied self-ignition of graptolitic argillite near Paldiski. At the University of Tartu oil shale geology and chemistry analyses were conducted during the 19th century by Georg Paul Alexander Petzholdt, Alexander Gustav von Schrenk, and Carl Ernst Heinrich Schmidt, among others.
Significant oil shale deposits are located in Israel (equal to about of shale oil) and in Jordan (equal to about of shale oil). In 2008, these resources were estimated of shale oil and of shale oil correspondingly. Jordan oil shales are high quality, comparable to western US oil shale, although their sulfur content is high. The best-explored deposits are El Lajjun, Sultani, and the Juref ed Darawish are located in west-central Jordan, while the Yarmouk deposit, close to its northern border, extends into Syria. Most of Israel's deposits are located in the Rotem Basin region of the northern Negev desert near the Dead Sea. Israeli oil shale is relatively low in heating value and oil yield.
The biggest oil shale reserves in Europe are located in Russia (equal to 35.47 billion metric tons of shale oil). Major deposits are located in the Volga-Petchyorsk province and in the Baltic Oil Shale Basin. Other major oil shale deposits in Europe are located in Italy (10.45 billion metric tons of shale oil), Estonia (2.49 billion metric tons of shale oil), France (1 billion metric tons of shale oil), Belarus (1 billion metric tons of shale oil), Sweden (875 million metric tons of shale oil), Ukraine (600 million metric tons of shale oil) and the United Kingdom (500 million metric tons of shale oil). There are oil shale reserves also in Germany, Luxembourg, Spain, Bulgaria, Hungary, Poland, Serbia, Austria, Albania, and Romania.
Spent shale or spent oil shale (also known as retorted shale) is a solid residue from the shale oil extraction process of producing synthetic shale oil from oil shale. It consists of inorganic compounds (minerals) and remaining organic matter known as char—a carbonaceous residue formed from kerogen. Depending on the extraction process and the amount of remaining organic matter, spent shale may be classified as oil shale coke, semi-coke or coke-ash residue, known also as oil shale ash. According to the European Union waste list all these types of spent shale are classified as hazardous waste.
At the start of the boom in 1915, oil and oil shale were still locateable minerals under the General Mining Act of 1872. Any US citizen could stake a placer claim to reserve the mineral rights over 160 acres of oil-shale land. Congress changed the situation when it passed the Mineral Leasing Act of 1920, which declared that oil and oil shale were no longer locateable minerals, but instead the rights to mine them had to be leased from the federal government.
In September 1920, of the many oil shale companies being promoted, none were yet in commercial-scale operation, although five were said to be close. Of the five, one plant was near Dragon, Utah, one at Salt Lake, two at Elko, Nevada, one at Denver, and one at Dillon, Montana. The plant at Dillon was mining oil shale of the Phosphoria Formation, Permian in age. The American Continuous Retort plant in Denver was receiving test lots from western Colorado, and as far away as Texas and Kentucky, largely on the proprietor’s claim that he could recover gold and platinum from the shale, along with the oil.
First attempt to produce oil from the western deposits was made by mining engineer Robert Catlin. Catlin became intrigued by oil shale, and in 1890 bought a plot of land near Elko Nevada that was underlain by oil shale of the Elko Formation. When the price of oil started rising in 1915, he dug a mine shaft down into the best yielding shale, built a bank of retorts and a small refinery, and began producing oil. He refined the oil into gasoline and lubricating oil, but the products were said to be of low quality. in 1917 he incorporated Catlin Shale Products Company. Catlin's plant at Elko produced about of oil from shale before he closed it in 1924. Catlin Shale Products Company was dissolved in 1930. Of the hundred-odd companies that formed to produce shale oil in the postwar boom, only Carlin's had actually done so on a commercial scale and marketed the product.
Oil shale gas is produced by retorting (pyrolysis) of oil shale. In the pyrolysis process, oil shale is heated until its kerogen decomposes into vapors of a petroleum-like condensable shale oil, non-condensible combustible oil shale gas, and spent shale—a solid residue. The process is the same as the shale oil extraction and oil shale gas usually occurs as a byproduct of shale oil production. The ratio of oil shale gas to shale oil depends on retorting temperature and as a rule, increases by the rise of temperature.
The Lurgi–Ruhrgas process is a hot recycled solids technology, which processes fine particles of coal or oil shale sized . As a heat carrier, it uses spent char or spent oil shale (oil shale ash), mixed with sand or other more durable materials. In this process, crushed coal or oil shale is fed into the top of the retort. In retort, coal or oil shale is mixed with the heated char or spent oil shale particles in the mechanical mixer (screw conveyor). The heat is transferred from the heated char or spent oil shale to the coal or raw oil shale causing pyrolysis. As a result, oil shale decomposes to shale oil vapors, oil shale gas and spent oil shale. The oil vapor and product gases pass through a hot cyclone for cleaning before sending to a condenser. In the condenser, shale oil is separated from product gases.
Shale oil was used for medical and military purposes. Mesopotamians used it for medical purposes and for caulking ships, Mongols used to cap their arrows with flaming oil shale. In the 10th century, the Arabian physician Masawaih al-Mardini (Mesue the Younger) described a method of extraction of oil from "some kind of bituminous shale". In the early 14th century, the first use of shale oil was recorded in Switzerland and Austria. In 1350, a knight Berthold von Ebenhausen was awarded a right to exploit the Seefeld oil shale in Tyrol. Oil shale was used for production of shale oil using an early retorting method of heating the crushed oil shale put in crucibles. The healing properties of a mineral oil distilled from oil shale were noted in 1596 by the personal physician of the Duke of Württemberg Frederick I.
The oil shale industry expanded immediately before World War I because of limited access to conventional petroleum resources and the mass production of automobiles and trucks, which accompanied an increase in gasoline consumption. Oil shale production in Scotland peaked in 1910–1912 with more than three million tonnes. That time Scottish shale oil industry contributed 2% of global oil production. After that, production declined with exception of the period of World War II. In 1919, five survived shale oil companies ("Young's Paraffin Light & Mineral Oil Company", "Broxburn Oil Company", "Pumpherston Shale Oil Company", "Oakbank Oil Company", and "James Ross & Company Philpstoun Oil Works"), were merged into Scottish Oils, a subsidiary of Anglo-Persian Oil Company.
In the United States the government started to create the Naval Petroleum and Oil Shale Reserves in 1909. The reserves were seen as a possible emergency source of fuel for the military, particularly the Navy. The government reserved the Roan Plateau near Rifle, Colorado which later became a federal demonstration and test site. First attempt to produce oil from the western deposits was made in Nevada by local businessman Robert Catlin by acquiring oil-shale properties in the 1890s and erecting the first retorts in 1915 and 1916. Although the attempt was commercially unsuccessful, in 1917 he incorporated Catlin Shale Products Company which made several unsuccessful attempts to sold shale oil products until it was dissolved in 1930. The first attempts to exploit the Green River Formation deposit was made by establishment of The Oil Shale Mining Company in 1916. In 1917, they erected the first commercial retort at the head of Dry Creek, near De Beque, Colorado. However, also these attempts were unsuccessful and by 1926 the company had lost its property. In addition, companies like Cities Service, Standard Oil of California, Texaco and Union started their oil shale operations in 1918–1920. In 1915–1920 about 200 companies were established to exploit oil shale and at least 25 shale oil retorting processes reached to the pilot-plant stage. Discoveries of the large quantities of petroleum in eastern Texas ended the oil-shale boom. One of technological achievements before World War II was invention of the N-T-U retort. In 1925, the NTU Company built a test plant at Sherman Cut near Casmalia, California. In 1925–1929, the retort was also tested by the United States Bureau of Mines in their Oil Shale Experiment Station at Anvil Point in Rifle, Colorado.
The Pumpherston retort was a high cylindrical vessel containing two main sections. The upper section was made of iron and the lower section was made of fire bricks. The raw oil shale was fed on the top of retort. Shale oil and oil shale gas were distilled at the upper section at the temperature of . At the lower section, the heat rose to and steam was added to produce ammonia. The process required approximately of water equivalent of steam per one ton of oil shale.
In this process, crushed oil shale is fed into the top of the retort where it is mixed with the hot oil shale ash. The oil shale moves downward through the retort as fluidized bed of particles. While descending, the heat is transferred from the oil shale ash to the raw oil shale causing pyrolysis. As a result, oil shale decomposes to shale oil vapors, oil shale gas and spent oil shale. A stripping gas is inserted from the bottom of retort, which carries oil vapors into solids separation section. The fine particles are directed to the combustor while oil vapors are moved to the condenser. In condenser, shale oil is separated from water vapor and product gases. On the bottom of retort the spent shale is transported to cumbustor.