How is oil shale made?
Oil shale
As source rocks for most conventional oil reservoirs, oil shale deposits are found in all world oil provinces, although most of them are too deep to be exploited economically. As with all oil and gas resources, analysts distinguish between oil shale resources and oil shale reserves. "Resources" refers to all oil shale deposits, while "reserves", represents those deposits from which producers can extract oil shale economically using existing technology. Since extraction technologies develop continuously, planners can only estimate the amount of recoverable kerogen.
Although resources of oil shale occur in many countries, only 33 countries possess known deposits of possible economic value .
Well-explored deposits, potentially classifiable as reserves, include the Green River deposits in the western United States, the Tertiary deposits in Queensland, Australia, deposits in Sweden and Estonia, the El-Lajjun deposit in Jordan, and deposits in France, Germany, Brazil, China, southern Mongolia and Russia. These deposits have given rise to expectations of yielding at least 40 liters of shale oil per tonne of oil shale, using the Fischer Assay.
History of the oil shale industry
In China, the "Refinery No. 2" of Fushun began its production in 1954 and in 1959, the maximum annual shale oil production increased to 780,000 tonnes. The produced shale oil was used for producing light liquid fuels. In 1961, China was producing one third of its total oil production from oil shale. Afterwards the shale oil production decreased due to the discovery of Daqing oil field and increased production of the cheaper conventional petroleum.
Oil shale geology
The organic portion of oil shale consists largely of a pre-bitumen bituminous groundmass, such as remains of algae, spores, pollen, plant cuticles and corky fragments of herbaceous and woody plants, and cellular debris from other lacustrine, marine, and land plants. While terrestrial oil shales contain resins, spores, waxy cuticles, and corky tissues of roots and stems of vascular terrestrial plants, lacustrine oil shales include lipid-rich organic matter derived from algae. Marine oil shales are composed of marine algae, acritarchs, and marine dinoflagellates. Organic matter in oil shale also contains organic sulfur (about 1.8% on average) and a lower proportion of nitrogen.
Shale gas
Shales that host economic quantities of gas have a number of common properties. They are rich in organic material (0.5% to 25%), 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.
Shale 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.
Oil shale in Jordan
Humans have used oil shale as a fuel since prehistoric times, because it generally burns without any processing. Its occurrence was known in Jordan from ancient times, as evidenced by its use as a building and decorative material from the ancient Greek, Roman, Byzantine, Umayyad and Abbasid periods. The modern exploitation of Jordanian oil shale began under Ottoman rule prior to and during World War I, when the German Army produced shale oil from the Yarmouk area. The oil shale was processed to operate the Hejaz Railway. It was mined and processed near the Maqarin station along the Haifa spur of the railroad, which partly follows the Yarmouk River valley. In addition to the shale oil production, oil shale was also utilized as a mix with coal to fuel locomotives.
History of the oil shale industry in the United States
The Green River oil “shale” is actually a marl, and some beds yield up to 70 gallons of oil per short ton of shale. Estimated in-place resources are capable of generating 4.2 trillion barrels of oil. Although the Piceance basin of western Colorado has the smallest lateral extent of Green River shale, it contains the greatest amount of high-grade shale. Using a cut-off of 25 gallons per ton, the Piceance has about 352 billion barrels of in-place resource.
Oil shale reserves
Oil shale formation takes place in a number of depositional settings and has considerable compositional variation. Oil shales can be classified by their composition (carbonate minerals such as calcite or detrital minerals such as quartz and clays) or by their depositional environment (large lakes, shallow marine, and lagoon/small lake settings). Much of the organic matter in oil shale 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.
History of the oil shale industry
Due to the 1973 oil crisis, the oil shale industry restarted in several countries. The United States Navy and the Office of Naval Petroleum and Oil Shale Reserves started evaluations of oil shale's suitability for military fuels, such as jet fuels, marine fuels and a heavy fuel oil. Shale-oil based JP-4 jet fuel was produced until the early 1990s, when it was replaced with kerosene-based JP-8. Seventeen companies led by Standard Oil of Ohio formed the Paraho Development Corporation to develop the Paraho process. Production started in 1974 but was closed in 1978. In 1974 the United States Department of the Interior announced an oil shale leasing program in the oil shale regions of Colorado and Utah. In 1980 the Synthetic Fuels Corporation was established which operated until 1985.
History of the oil shale industry in the United States
Attracted by rising oil prices, and the promise of a permanent shortage of petroleum, oil-shale prospectors swarmed over the Piceance and Uinta basins of Colorado and Utah. Some established oil companies joined the rush, but about 100 new companies formed to mine and process oil shale, and, not incidentally, to sell shares of stock. Many of them built retorts to extract the shale oil.
Oil shale industry
Although there are several oil shale retorting technologies, only four technologies are currently in commercial use. These are Kiviter, Galoter, Fushun, and Petrosix. The two main methods of extracting oil from shale are "ex-situ" and "in-situ". In "ex-situ" method, the oil shale is mined and transported to the retort facility in order to extract the oil. The "in-situ" method converts the kerogen while it is still in the form of an oil shale deposit, and then extracts it via a well, where it rises up as normal petroleum.
Shale oil extraction
"By raw oil shale particle size": The various "ex situ" processing technologies may be differentiated by the size of the oil shale particles that are fed into the retorts. As a rule, gas heat carrier technologies process oil shale lumps varying in diameter from , while solid heat carrier and wall conduction technologies process fines which are particles less than in diameter.
Spent shale
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.
Oil shale in China
Longkou Mining Group, subsidiary of Shandong Energy, produces oil shale as a coal mining byproduct. It operates shale oil plant which is equipped with 40 Fushun retorts. The shale oil production is about 120,000 tonnes per year and the planned full capacity is 200,000 tonnes of shale oil per year. The company also plans to utilize Enefit-280 technology. In addition, the company plans to burn shale char mixed with particulate oil shale in fluidized bed combustion for power generation, and the shale ash would be utilized for production of building material.
History of the oil shale industry
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
, industry uses oil shale in Brazil, China, Estonia and to some extent in Germany, and Russia. Several additional countries started assessing their reserves or had built experimental production plants, while others had phased out their oil shale industry. Oil shale serves for oil production in Estonia, Brazil, and China; for power generation in Estonia, China, and Germany; for cement production in Estonia, Germany, and China; and for use in chemical industries in China, Estonia, and Russia.
Shale oil
The amount of oil that can be recovered during retorting varies with the oil shale and the technology used. About one sixth of the oil shales in the Green River Formation have a relatively high yield of of shale oil per ton of oil shale; about one third yield from 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.
Shale
Shale is a fine-grained, clastic sedimentary rock composed of mud that is a mix of flakes of clay minerals and tiny fragments (silt-sized particles) of other minerals, especially quartz and calcite. Shale is characterized by breaks along thin laminae or parallel layering or bedding less than one centimeter in thickness, called fissility. It is the most common sedimentary rock.
Combustion Resources
Combustion Resources worked under a grant from the US Department of Energy to research and optimize current designs of shale oil extraction. It seeked to eliminate carbon dioxide emissions from the shale oil production process. Pyrolysis occurs in a rotating kiln heated by hot gas flowing through an outer annulus. The hot gas is created by burning hydrogen generated in a separate unit by coal gasification followed by carbon dioxide separation. The geometry of the annulus enables the transfer of heat to the moving shale through a wall.
History of the oil shale industry in the United States
The second category of eastern oil-shale resources are the Paleozoic black shales, of lower oil yield, but of much larger size than the cannel coals. Most attention has been given to the shales near the Devonian/Mississippian boundary, which are variously called the Ohio Shale, Chattanooga Shale, the Antrim Shale, and the New Albany Shale.
Shale oil extraction
In the CCR Process proposed by American Shale Oil, superheated steam or another heat transfer medium is circulated through a series of pipes placed below the oil shale layer to be extracted. The system combines horizontal wells, through which steam is passed, and vertical wells, which provide both vertical heat transfer through refluxing of converted shale oil and a means to collect the produced hydrocarbons. Heat is supplied by combustion of natural gas or propane in the initial phase and by oil shale gas at a later stage.
History of the oil shale industry in the United States
By the 1940s, companies such as Chevron and Texaco owned substantial oil shale areas. A number of oil companies started researching methods to mining and process the oil shale. In contrast to the boom of the 1920s, which featured hundreds of small startup companies operating on stock sales, the shale research after World War II was a well-financed, long-term effort by established oil companies. 
Sinclair Oil began testing an "in-situ" combustion process for recovering shale oil in the 1950s. Union Oil Company of California built and tested its proprietary Union process with a 1,200 ton-per-day retort at its Parachute Creek property near Grand Valley, Colorado in 1957 and 1958. This technology was tested between 1954 and 1958 at the company-owned tract in the Parachute Creek. This production was finally shut down in 1961 due to cost. In 1957 Texaco built a shale oil extraction pilot plant to develop its own hydroretorting process. In the early 1960s TOSCO (The Oil Shale Corporation) opened an underground mine and built an experimental plant near Parachute, Colorado. It was closed in 1972 because the price of production exceeded the cost of imported crude oil. The federal government offered for lease three large blocks of oil shale land in Colorado in 1968, but rejected all the received bids as insufficient.
Oil shale geology
As source rocks for most conventional oil reservoirs, oil shale deposits are found in all world oil provinces, although most of them are too deep to be exploited economically. As with all oil and gas resources, analysts distinguish between oil shale resources and oil shale reserves. "Resources" refers to all oil shale deposits, while "reserves", represents those deposits from which producers can extract oil shale economically using existing technology. Since extraction technologies develop continuously, planners can only estimate the amount of recoverable kerogen.
Although resources of oil shale occur in many countries, only 33 countries possess known deposits of possible economic value.
Well-explored deposits, potentially classifiable as reserves, include the Green River deposits in the western United States, the Tertiary deposits in Queensland, Australia, deposits in Sweden and Estonia, the El-Lajjun deposit in Jordan, and deposits in France, Germany, Brazil, China, southern Mongolia and Russia. These deposits have given rise to expectations of yielding at least 40 liters of shale oil per tonne of oil shale, using the Fischer Assay.
Union process
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.
Unconventional oil
Oil shale is an organic-rich fine-grained sedimentary rock containing significant amounts of kerogen (a solid mixture of organic chemical compounds) from which technology can extract liquid hydrocarbons (shale oil) and combustible oil shale gas. The kerogen in oil shale can be converted to shale oil through the chemical processes of pyrolysis, hydrogenation, or thermal dissolution. The temperature when perceptible decomposition of oil shale occurs depends on the time-scale of the pyrolysis; in the above ground retorting process the perceptible decomposition occurs at , but proceeds more rapidly and completely at higher temperatures. The rate of decomposition is the highest at a temperature of to . The ratio of shale gas to shale oil depends on the retorting temperature and as a rule increases with the rise of temperature. For the modern "in-situ" process, which might take several months of heating, decomposition may be conducted as low as . Depending on the exact properties of oil shale and the exact processing technology, the retorting process may be water and energy extensives. Oil shale has also been burnt directly as a low-grade fuel.
History of the oil shale industry
In Australia, the first oil shale mine was commenced in 1865 at American Creek, Mount Kembla in New South Wales. At the same year, the first shale oil was produced by the Pioneer Kerosene Works at American Creek. A number of other mines and shale oil plants were opened in New South Wales; however, in the beginning of the 20th century they were closed due to the import of cheaper crude oil.
History of the oil shale industry
In China, the extraction of oil shale began in 1926 under the Japanese rule. The commercial-scale production of shale oil began in 1930 in Fushun, Manchuria, with the construction of the "Refinery No. 1" operating Fushun-type retorts. In Russia, Kashpirskoye oil shale near Syzran in the Volga region was mined and processed in 1919–1924 and again starting from 1929. Leningradslanets opened the Kirov oil shale mine in 1934 in Slantsy, Leningrad Oblast and shale oil production started in 1939. Saratov and Syzran power stations in Russia started to use oil shale as fuel. In South Africa different attempts of using oil shale were made since beginning of century. In 1903 the Transvaal Oil Shale Syndicate investigated oil shale at Kikvorschfontein. In 1919–1931 the African Oil Corporation investigated oil shale at Kromhoek and Goedgevonden. In 1935, The South African Torbanite Mining and Refining Company, a joint venture of Anglo-Transvaal Consolidated Investment Company and Burmah Oil opened shale oil plant at Ermelo in 1935.
TOSCO II process
The TOSCO II process is classified as a hot recycled solids technology. It employs a horizontal rotating kiln-type retort. In this process, oil shale is crushed smaller than and enters the system through pneumatic lift pipes in which oil shale is elevated by hot gas streams and preheated to about . After entering into retort, oil shale is mixed with hot ceramic balls with temperature from to . This increase the oil shale temperature to between and , in which pyrolysis occurs. In the pyrolysis process, kerogen decomposes to oil shale gas and oil vapors, while the remainder of the oil shale forms spent shale. Vapors are transferred to a condensor (fractionator) for separation into various fractions. At the kiln passage, the spent shale and the ceramic balls are separated in a perforated rotating separation drum (trommel). The crushed spent shale falls through holes in the trommel, while ceramic balls are transferred to the ball heater. Combustible shale gas is burned in the ball heater to reheat the ceramic balls.
Oil shale industry
In a 1972 publication by the journal "Pétrole Informations" (ISSN 0755-561X), shale oil production was unfavorably compared to the coal liquefaction. The article stated that coal liquefaction was less expensive, generated more oil, and created fewer environmental impacts than oil shale extraction. It cited a conversion ratio of of oil per one tonne of coal, as against of shale oil per one tonne of oil shale.
Oil shale in China
In 1954, the "Refinery No. 2" began its production and in 1959, the maximum annual shale oil production increased to 780,000 tonnes. The produced shale oil was acid and alkaline washed and hydrotreated for producing light liquid fuels. In 1961, China was producing one third of its total oil production from oil shale. In Maoming, Guangdong Province, a new oil shale retorting plant with 64 retorts was put into operation in 1963.
Oil shale economics
The economic feasibility of oil shale is highly dependent on the price of conventional oil, and the assumption that the price will remain at a certain level for some time to come. As a developing fuel source the production and processing costs for oil shale are high due to the small nature of the projects and the specialist technology involved. A full-scale project to develop oil shale would require heavy investment and could potentially leave businesses vulnerable should the oil price drop and the cost of producing the oil would exceed the price they could obtain for the oil.
Shale oil extraction
Shale oil extraction is usually performed above ground ("ex situ" processing) by mining the oil shale and then treating it in processing facilities. Other modern technologies perform the processing underground (on-site or "in situ" processing) by applying heat and extracting the oil via oil wells.
Shale oil extraction
Hot recycled solids technologies deliver heat to the oil shale by recycling hot solid particles—typically oil shale ash. These technologies usually employ rotating kiln or fluidized bed retorts, fed by fine oil shale particles generally having a diameter of less than ; some technologies use particles even smaller than . The recycled particles are heated in a separate chamber or vessel to about and then mixed with the raw oil shale to cause the shale to decompose at about . Oil vapour and shale oil gas are separated from the solids and cooled to condense and collect the oil. Heat recovered from the combustion gases and shale ash may be used to dry and preheat the raw oil shale before it is mixed with the hot recycle solids.
Oil shale
Mining oil shale involves a number of environmental impacts, more pronounced in surface mining than in underground mining. These include acid drainage induced by the sudden rapid exposure and subsequent oxidation of formerly buried materials, the introduction of metals including mercury into surface-water and groundwater, increased erosion, sulfur-gas emissions, and air pollution caused by the production of particulates during processing, transport, and support activities. In 2002, about 97% of air pollution, 86% of total waste and 23% of water pollution in Estonia came from the power industry, which uses oil shale as the main resource for its power production.
Oil shale geology
No consensus has been reached on the exact depositional nature of the Irati oil shale. One theory suggests that the organic material in the Irati oil shale originated from algae deposited in a lacustrine environment with salinity varying from that of freshwater to brackish water. Other theory suggests that the organic sediment may have been deposited in a shallow, partially restricted marine environment. Hutton's classification describes it as a marine source oil shale.
Oil shale
The shale oil derived from oil shale does not directly substitute for crude oil in all applications. It may contain higher concentrations of olefins, oxygen, and nitrogen than conventional crude oil. Some shale oils may have higher sulfur or arsenic content. By comparison with West Texas Intermediate, the benchmark standard for crude oil in the futures-contract market, the Green River shale oil sulfur content ranges from near 0% to 4.9% (in average 0.76%), where West Texas Intermediate's sulfur content has a maximum of 0.42%. The sulfur content in shale oil from Jordan's oil shales may rise even up to 9.5%. The arsenic content, for example, becomes an issue for Green River formation oil shale. The higher concentrations of these materials means that the oil must undergo considerable upgrading (hydrotreating) before serving as oil-refinery feedstock. Above-ground retorting processes tended to yield a lower API gravity shale oil than the "in situ" processes. Shale oil serves best for producing middle-distillates such as kerosene, jet fuel, and diesel fuel. Worldwide demand for these middle distillates, particularly for diesel fuels, increased rapidly in the 1990s and 2000s. However, appropriate refining processes equivalent to hydrocracking can transform shale oil into a lighter-range hydrocarbon (gasoline).
Shale oil extraction
In general, externally generated hot gas technologies are similar to internal combustion technologies in that they also process oil shale lumps in vertical shaft kilns. Significantly, though, the heat in these technologies is delivered by gases heated outside the retort vessel, and therefore the retort vapors are not diluted with combustion exhaust. The Petrosix and Paraho Indirect employ this technology. In addition to not accepting fine particles as feed, these technologies do not utilize the potential heat of combusting the char on the spent shale and thus must burn more valuable fuels. However, due to the lack of combustion of the spent shale, the oil shale does not exceed and significant carbonate mineral decomposition and subsequent CO generation can be avoided for some oil shales. Also, these technologies tend to be the more stable and easier to control than internal combustion or hot solid recycle technologies.
Shale oil
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. Additional cracking can create the lighter hydrocarbons used in gasoline.
LLNL HRS process
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.
Unconventional oil
According to a survey conducted by the RAND Corporation, the cost of producing a barrel of oil at a surface retorting complex in the United States (comprising a mine, retorting plant, upgrading plant, supporting utilities, and spent shale reclamation), would range between US$70–95 ($440–600/m, adjusted to 2005 values). , industry uses oil shale for shale oil production in Brazil, China and Estonia. Several additional countries started assessing their reserves or had built experimental production plants. In the USA, if oil shale could be used to meet a quarter of the current demand, of recoverable resources would last for more than 400 years.
Shale oil extraction
In the 10th century, the Arabian physician Masawaih al-Mardini (Mesue the Younger) wrote of his experiments in extracting oil from "some kind of bituminous shale". The first shale oil extraction patent was granted by the British Crown in 1684 to three people who had "found a way to extract and make great quantities of pitch, tarr, and oyle out of a sort of stone". Modern industrial extraction of shale oil originated in France with the implementation of a process invented by Alexander Selligue in 1838, improved upon a decade later in Scotland using a process invented by James Young. During the late 19th century, plants were built in Australia, Brazil, Canada, and the United States. The 1894 invention of the Pumpherston retort, which was much less reliant on coal heat than its predecessors, marked the separation of the oil shale industry from the coal industry.
Environmental impact of the oil shale industry
Disposal of mining wastes, spent oil shale (including semi-coke) and combustion ashes needs additional land use. According to the study of the European Academies Science Advisory Council, after processing, the waste material occupies a greater volume than the material extracted, and therefore cannot be wholly disposed underground. According to this, production of a barrel of shale oil can generate up to 1.5 tonnes of semi-coke, which may occupy up to 25% greater volume than the original shale. This is not confirmed by the results of Estonia's oil shale industry. The mining and processing of about one billion tonnes of oil shale in Estonia has created about 360-370 million tonnes of solid waste, of which 90 million tonnes is a mining waste, 70–80 million tonnes is a semi-coke, and 200 million tonnes are combustion ashes.
Oil shale
A critical measure of the viability of oil shale as an energy source lies in the ratio of the energy produced by the shale to the energy used in its mining and processing, a ratio known as "Energy Returned on Energy Invested" (EROEI). A 1984 study estimated the EROEI of the various known oil-shale deposits as varying between 0.7–13.3
although known oil-shale extraction development projects assert an EROEI between 3 and 10. According to the World Energy Outlook 2010, the EROEI of "ex-situ" processing is typically 4 to 5 while of "in-situ" processing it may be even as low as 2. However, according to the IEA most of used energy can be provided by burning the spent shale or oil-shale gas.
Shale oil
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. In response to rising petroleum costs at the turn of the 21st century, extraction operations have commenced, been explored, or been renewed in the United States, China, Australia and Jordan.
Petroleum
On the other hand, oil shales are source rocks that have not been exposed to heat or pressure long enough to convert their trapped hydrocarbons into crude oil. Technically speaking, oil shales are not always shales and do not contain oil, but are fined-grain sedimentary rocks containing an insoluble organic solid called kerogen. The kerogen in the rock can be converted into crude oil using heat and pressure to simulate natural processes. The method has been known for centuries and was patented in 1694 under British Crown Patent No. 330 covering, "A way to extract and make great quantities of pitch, tar, and oil out of a sort of stone." Although oil shales are found in many countries, the United States has the world's largest deposits.
Fossil fuel
Heavy crude oil, which is much more viscous than conventional crude oil, and oil sands, where bitumen is found mixed with sand and clay, began to become more important as sources of fossil fuel as of the early 2000s. Oil shale and similar materials are sedimentary rocks containing kerogen, a complex mixture of high-molecular weight organic compounds, which yield synthetic crude oil when heated (pyrolyzed). These materials have yet to be fully exploited commercially. With additional processing, they can be employed in lieu of other already established fossil fuel deposits. More recently, there has been disinvestment from exploitation of such resources due to their high carbon cost, relative to more easily processed reserves.
Oil shale
General composition of oil shales constitutes inorganic matrix, bitumens, and kerogen. Oil shales differ from oil-"bearing" shales, shale deposits that contain petroleum (tight oil) that is sometimes produced from drilled wells. Examples of oil-"bearing" shales are the Bakken Formation, Pierre Shale, Niobrara Formation, and Eagle Ford Formation.
Oil shale
"In-situ" processing involves heating the oil shale underground. Such technologies can potentially extract more oil from a given area of land than "ex-situ" processes, since they can access the material at greater depths than surface mines can. Several companies have patented methods for "in-situ" retorting. However, most of these methods remain in the experimental phase. One can distinguish "true in-situ" processes (TIS) and "modified in-situ" processes (MIS). "True in-situ" processes do not involve mining the oil shale. "Modified in-situ" processes involve removing part of the oil shale and bringing it to the surface for modified "in-situ" retorting in order to create permeability for gas flow in a rubble chimney. Explosives rubblize the oil-shale deposit.
Oil shale industry
Oil shale can be used as a fuel in thermal power plants, wherein oil shale is burnt like coal to drive the steam turbines. As of 2012, there are oil shale-fired power plants in Estonia with a generating capacity of 2,967 megawatts (MW), China, and Germany.
Also Israel, Romania and Russia have run oil shale-fired power plants, but have shut them down or switched to other fuels like natural gas. Jordan and Egypt have announced their plans to construct oil shale-fired power plants, while Canada and Turkey plan to burn oil shale at the power plants along with coal.
Oil shale in Estonia
In the 18th and 19th centuries, Estonian oil shale was described by several scientists and used as a low-grade fuel. Its use in industry commenced in 1916. Production of shale oil began in 1921 and oil shale was first used to generate electrical power in 1924. Shortly thereafter, systematic research into oil shale and its products began, and in 1938 a department of mining was established at Tallinn Technical University. After World War II, Estonian oil shale gas was used in Saint Petersburg (then called Leningrad) and in northern cities in Estonia as a substitute for natural gas. Increased need for electricity in the north-west of the Soviet Union led to the construction of large oil shale-fired power stations. Oil shale extraction peaked in 1980. Subsequently, the launch of nuclear reactors in Russia, particularly the Leningrad Nuclear Power Station, reduced demand for electricity produced from oil shale, and, along with a post-Soviet restructuring of the industry in the 1990s, led to a decrease in oil shale mining. After decreasing for two decades, oil shale mining started to increase again at the beginning of the 21st century.
Oil shale in China
The Tertiary age Maoming oil-shale deposit is long, wide, and to thick. The ore is yellow brown and the bulk density is about 1.85. The oil shale contains 72.1% ash, 10.8% moisture, 1.2% sulfur, with a heating value of 1,745 kcal/kg (dry basis). It is not suitable for above-ground retorting, but it could be used for a power generation by a fluidized bed combustion.
Oil sands
Except for a fraction of the extra-heavy oil or bitumen which can be extracted by conventional oil well technology, oil sands must be produced by strip mining or the oil made to flow into wells using sophisticated "in-situ" techniques. These methods usually use more water and require larger amounts of energy than conventional oil extraction. While much of Canada's oil sands are being produced using open-pit mining, approximately 90% of Canadian oil sands and all of Venezuela's oil sands are too far below the surface to use surface mining.
Oil shale
Another classification, known as the van Krevelen diagram, assigns kerogen types, depending on the hydrogen, carbon, and oxygen content of oil shales' original organic matter. The most commonly used classification of oil shales, developed between 1987 and 1991 by Adrian C. Hutton, adapts petrographic terms from coal terminology. This classification designates oil shales as terrestrial, lacustrine (lake-bottom-deposited), or marine (ocean bottom-deposited), based on the environment of the initial biomass deposit. Known oil shales are predominantly aquatic (marine, lacustrine) origin. Hutton's classification scheme has proven useful in estimating the yield and composition of the extracted oil.
History of the oil shale industry in the United States
There are two types of oil shale resources in the United States east of the Mississippi River. The first is cannel coal, which was used widely in Kentucky, Ohio, Pennsylvania, and western Virginia (now West Virginia) to manufacture oil during the first American oil shale boom, 1854-1861. The cannel coals have since been largely mined out, and are no longer considered a major oil-shale resource.
Oil shale in China
Maoming oil shale industry was developed from the 1960s to the 1990s by Maoming Petrochemical Company, a subsidiary of Sinopec, which built 64 Fushun-type retorts and 48 gas combustion retorts for producing shale oil. The production peaked with 180,000 tonnes of shale oil per annum. This industry was shut down in the 1990s. The Guandong Province authorities have a plan to use the Maoming oil shale for the power production using fluidized bed combustion. In 2008, one circulating fluidized-bed boiler was constructed. Guangdong Electricity Company has plans to build a power station with capacity of 1,200 MW.
Oil shale
The extraction of the useful components of oil shale usually takes place above ground ("ex-situ" processing), although several newer technologies perform this underground (on-site or "in-situ" processing).
In either case, the chemical process of pyrolysis converts the kerogen in the oil shale to shale oil (synthetic crude oil) and oil shale gas. Most conversion technologies involve heating shale in the absence of oxygen to a temperature at which kerogen decomposes (pyrolyses) into gas, condensable oil, and a solid residue. This usually takes place between and . The process of decomposition begins at relatively low temperatures (), but proceeds more rapidly and more completely at higher temperatures.
Oil shale
Most exploitation of oil shale involves mining followed by shipping elsewhere, after which one can burn the shale directly to generate electricity, or undertake further processing. The most common methods of surface mining involve open pit mining and strip mining. These procedures remove most of the overlying material to expose the deposits of oil shale, and become practical when the deposits occur near the surface. Underground mining of oil shale, which removes less of the overlying material, employs the room-and-pillar method.
Shale oil extraction
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.
American Shale Oil
AMSO developed a process called "Conduction, Convection, Reflux" (CCR) oil shale conversion. The process combines horizontal wells, which are heated by a downhole burner or other means, and other horizontal or vertical wells, which provide both heat transfer through refluxing of generated oil and a means to collect and produce the oil. At the start of the heating process, oil is injected to improve heat transfer. AMSO has proposed that permeability of the formation sufficient for convection will be achieved by thermomechanical fracturing. The original technology proposed by EGL was based on hydraulic fracturing.)
Shale oil
The production of shale oil has been hindered because of technical difficulties and costs. In March 2011, the United States Bureau of Land Management called into question proposals in the U.S. for commercial operations, stating that "There are no economically viable ways yet known to extract and process oil shale for commercial purposes."
Shale oil extraction
Externally generated hot gas "in situ" technologies use hot gases heated above-ground and then injected into the oil shale formation. The Chevron CRUSH process, which was researched by Chevron Corporation in partnership with Los Alamos National Laboratory, injects heated carbon dioxide into the formation via drilled wells and to heat the formation through a series of horizontal fractures through which the gas is circulated. General Synfuels International has proposed the Omnishale process involving injection of super-heated air into the oil shale formation. Mountain West Energy's In Situ Vapor Extraction process uses similar principles of injection of high-temperature gas.
Oil shale economics
A measure of the viability of oil shale as a fuel source is the ratio of the energy produced to the energy used converting it (Energy Returned on Energy Invested - EROEI). The value of the EROEI for oil shale is difficult to calculate for a number of reasons. Lack of reliable studies of modern oil shale processes, poor or undocumented methodology and a limited number of operational facilities are the main reasons. Due to technically more complex processes, the EROEI for oil shale is below the EROEI of about 20:1 for conventional oil extraction at the wellhead.
Shale oil extraction
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
A 1972 publication in the journal "Pétrole Informations" () compared shale-based oil production unfavorably with coal liquefaction. The article portrayed coal liquefaction as less expensive, generating more oil, and creating fewer environmental impacts than extraction from oil shale. It cited a conversion ratio of of oil per one ton of coal, as against of shale oil per one ton of oil shale.
Oil shale industry
A critical measure of the viability of oil shale as an energy source lies in the ratio of the energy produced by the shale to the energy used in its mining and processing, a ratio known as "Energy Returned on Energy Invested" (EROEI). A 1984 study estimated the EROEI of the various known oil-shale deposits as varying between 0.7–13.3
although known oil-shale extraction development projects assert an EROEI between 3 and 10. According to the World Energy Outlook 2010, the EROEI of "ex-situ" processing is typically 4 to 5 while of "in-situ" processing it may be even as low as 2. However, according to the IEA most of used energy can be provided by burning the spent shale or oil-shale gas.
Shale oil extraction
For "ex situ" processing, oil shale is crushed into smaller pieces, increasing surface area for better extraction. The temperature at which decomposition of oil shale occurs depends on the time-scale of the process. In "ex situ" retorting processes, it begins at and proceeds more rapidly and completely at higher temperatures. The amount of oil produced is the highest when the temperature ranges between . The ratio of oil shale gas to shale oil generally increases along with retorting temperatures. For a modern "in situ" process, which might take several months of heating, decomposition may be conducted at temperatures as low as . Temperatures below are preferable, as this prevents the decomposition of lime stone and dolomite in the rock and thereby limits carbon dioxide emissions and energy consumption.
Oil shale geology
Oil shales have been divided into three categories based on mineral composition – carbonate-rich shale, siliceous shale and cannel shale. Carbonate-rich shales derive their name from the large amount of carbonate minerals such as calcite and dolomite. As many as twenty carbonate minerals have been found in oil shales, the majority of which are considered authigenic or diagenetic. Carbonate-rich oil shales, particularly that of lacustrine-sourced deposits, have usually the organic-rich layers sandwiched between carbonate-rich layers. These deposits are hard formations that are resistant to weathering and they are difficult to process using "ex-situ" methods. Siliceous oil shales are usually dark brown or black shales. They are not rich in carbonates but rather in siliceous minerals such as quartz, feldspar, clay, chert and opal. Siliceous shales are not as hard and weather-resistant as carbonate-rich shales, and may be better suited for extraction via "ex-situ" methods. Cannel shales are usually dark brown or black shales, which consist of organic matter that completely encloses other mineral grains. They are suitable for extraction via "ex-situ" methods.
Oil shale gas
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.
Shale oil extraction
"By location": A frequently used distinction considers whether processing is done above or below ground, and classifies the technologies broadly as "ex situ" (displaced) or "in situ" (in place). In "ex situ" processing, also known as above-ground retorting, the oil shale is mined either underground or at the surface and then transported to a processing facility. In contrast, "in situ" processing converts the kerogen while it is still in the form of an oil shale deposit, following which it is then extracted via oil wells, where it rises in the same way as conventional crude oil. Unlike "ex situ" processing, it does not involve mining or spent oil shale disposal aboveground as spent oil shale stays underground.
Oil shale industry
The amount of economically recoverable oil shale is unknown. The various attempts to develop oil shale deposits have succeeded only when the cost of shale-oil production in a given region comes in below the price of crude oil or its other substitutes.
According to a survey conducted by the RAND Corporation, the cost of producing a barrel of shale oil at a hypothetical surface retorting complex in the United States (comprising a mine, retorting plant, upgrading plant, supporting utilities, and spent shale reclamation), would range between US$70–95 ($440–600/m), adjusted to 2005 values. Assuming a gradual increase in output after the start of commercial production, the analysis projects a gradual reduction in processing costs to $30–40 per barrel ($190–250/m) after achieving the milestone of . Royal Dutch Shell has announced that its Shell ICP technology would realize a profit when crude oil prices are higher than $30 per barrel ($190/m), while some technologies at full-scale production assert profitability at oil prices even lower than $20 per barrel ($130/m).
History of the oil shale industry in the United States
Concern about long-term oil supplies during World War II had prompted Congress in 1944 to pass the Synthetic Liquid Fuels Program with goal to establish a liquid fuel supply from domestic oil shale. It funded oil-shale studies by the US Bureau of Mines. The Bureau of Mines built a test facility at Anvil Points on Naval Oil Shale Reserve 1, to test methods of mining, crushing, and retorting the Green River oil shales. It started to develop the gas combustion retort process. In 1943 Mobil Oil built a pilot shale oil extraction plant and in 1944 Union built an experimental oil shale retort. In 1945 Texaco started shale oil refining study.
Oil shale reserves
As source rocks for most conventional oil reservoirs, oil shale deposits are found in all world oil provinces, although most of them are too deep to be exploited economically. There are more than 600 known oil shale deposits around the world. Although resources of oil shale occur in many countries, only 33 countries possess known deposits of possible economic value.
Synthetic fuels in the United States
The United States Bureau of Mines opened a demonstration oil shale mine at Anvils Point, west of Rifle, Colorado, which operated at a small scale. In the early 1960s TOSCO (The Oil Shale Corporation) opened an underground mine and built an experimental plant near Parachute, Colorado. It was closed in 1972 because the price of production exceeded the cost of imported crude oil. In 1951, the United States Department of Defense became interested in oil shale as an alternative resource for producing a jet fuel.
Oil shale geology
The oil shale that underlies almost in the eastern United States was formed in a marine depositional environment, very different from the Green River Basins. These deposits have also undergone commercialization attempts; they are also resources for natural gas and have been mined for low-grade oil shale. These oil shales were formed during the Late Devonian and Early Mississippian periods. During this time, much of the eastern United States was covered by a large shallow sea. The oil shale is thought to have been the result of slow deposition of planktonic algae. under anoxic conditions. In parts of the basin close to the shoreline, the organic mixture that helped form the oil shale contains organic-rich sediment from the rising Appalachian mountains.
Oil shale geology
Though similar in their formation process, oil shales differ from coals in several distinct ways. The precursors of the organic matter in oil shale and coal differ in a sense that oil shale is of algal origin, but may also include remains of vascular land plants that more commonly compose much of the organic matter in coal. The origin of some of the organic matter in oil shale is obscure because of the lack of recognizable biologic structures that would help identify the precursor organisms. Such materials may be of bacterial origin or the product of bacterial degradation of algae or other organic matter.
Shale oil extraction
The dominant question for shale oil production is under what conditions shale oil is economically viable. According to the United States Department of Energy, the capital costs of a "ex-situ" processing complex are $3–10 billion. The various attempts to develop oil shale deposits have succeeded only when the shale-oil production cost in a given region is lower than the price of petroleum or its other substitutes. According to a survey conducted by the RAND Corporation, the cost of producing shale oil at a hypothetical surface retorting complex in the United States (comprising a mine, retorting plant, upgrading plant, supporting utilities, and spent oil shale reclamation), would be in a range of $70–95 per barrel ($440–600/m), adjusted to 2005 values. Assuming a gradual increase in output after the start of commercial production, the analysis projects a gradual reduction in processing costs to $30–40 per barrel ($190–250/m) after achieving the milestone of . The United States Department of Energy estimates that the "ex-situ" processing would be economic at sustained average world oil prices above $54 per barrel and "in-situ" processing would be economic at prices above $35 per barrel. These estimates assume a return rate of 15%. Royal Dutch Shell announced in 2006 that its Shell ICP technology would realize a profit when crude oil prices are higher than $30 per barrel ($190/m), while some technologies at full-scale production assert profitability at oil prices even lower than $20 per barrel ($130/m).
Oil shale in Estonia
The combustion of oil shale releases more into the atmosphere than any other primary fuel. Generating 1 MWh of electricity in modern oil shale-fired boilers creates 0.9–1 tonnes of . Therefore, oil shale industry is the chief source – more than 70% – of greenhouse gas emissions in Estonia. Due to the oil shale-based electricity generation, Estonia's has the second highest greenhouse gas emissions relative to GDP among the OECD and the fifth highest emissions per capita among the IEA countries. The whole energy sector of Estonia emitted the equivalent 17 million tonnes of greenhouse gases in 2012. In order to reduce the country's emissions and to meet the emissions reduction targets, use of oil shale in electricity generation needs to be scaled down. emissions in Estonia could be reduced by two-thirds if oil shale would be used for production of lighter oil products instead of burning it for electricity generation. It could be achieved by raising taxes on oil shale use and harmonizing tax rates of fossil fuels according to the emission content.
History of the oil shale industry in the United States
As the price of whale oil escalated, scientists tried to create a cheap, artificial oil that would burn with a bright, smokeless flame, safer than “burning oil.” Two succeeded: Scottish chemist James Young, and Canadian geologist Abraham Gesner. Both distilled their lamp oils from coal or coal-like raw materials. James Young made his from coal, and discovered that the coal that yielded the most oil was cannel coal. Young filed a patent for his process in 1850, and built a highly successful plant at Bathgate, Scotland making an illuminating oil he called “paraffine,” from the cannel coal that was mined nearby, the Boghead coal, which yielded more oil than any of the other coals he tested.
Oil shale economics
The various attempts to develop oil shale deposits have succeeded only when the cost of shale-oil production in a given region comes in below the price of crude oil or its other substitutes (break-even price). The United States Department of Energy estimates that the "ex-situ" processing would be economic at sustained average world oil prices above US$$54 per barrel and "in-situ" processing would be economic at prices above $35 per barrel. These estimates assume a return rate of 15%. The International Energy Agency estimates, based on the various pilot projects, that investment and operating costs would be similar to those of Canadian oil sands, that means would be economic at prices above $60 per barrel at current costs. This figure does not account carbon pricing, which will add additional cost. According to the New Policies Scenario introduced in its World Energy Outlook 2010, a price of $50 per tonne of emitted , expected by 2035, will add additional $7.50 per barrel cost of shale oil.
History of the oil shale industry in the United States
The first American shale oil/coal oil manufacturer using non-imported coal was the Breckinridge Cannel Coal Company, chartered by the Kentucky legislature in 1854. In 1856 its twelve new retorts at Cloverport, Kentucky began producing of lamp oil each day. The company had the advantages of proximity to large deposits of cannel coal from the Breckinridge coal deposit in Hancock County, Kentucky, and a location on the Ohio River, providing cheap shipping to markets. Commercial-scale shale oil extraction, other than cannel coal processing, began at shale oil retorts using the Devonian oil shale along the Ohio River Valley in 1857.
Petrosix
Petrosix is one of four technologies of shale oil extraction in commercial use. It is an above-ground retorting technology, which uses externally generated hot gas for the oil shale pyrolysis. After mining, the shale is transported by trucks to a crusher and screens, where it is reduced to particles (lump shale). These particles are between and and have an approximately parallelepipedic shape. These particles are transported on a belt to a vertical cylindrical vessel, where the shale is heated up to about for pyrolysis. Oil shale enters through the top of the retort while hot gases are injected into the middle of the retort. The oil shale is heated by the gases as it moves down. As a result, the kerogen in the shale decomposes to yield oil vapor and more gas. Cold gas is injected into the bottom of the retort to cool and recover heat from the spent shale. Cooled spent shale is discharged through a water seal with drag conveyor below the retort. Oil mist and cooled gases are removed through the top of the retort and enter a wet electrostatic precipitator where the oil droplets are coalesced and collected. The gas from the precipitator is compressed and split into three parts.
Shale oil
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.
Oil shale
According to the World Energy Council, in 2008 the total production of shale oil from oil shale was 930,000 tonnes, equal to , of which China produced 375,000 tonnes, Estonia 355,000 tonnes, and Brazil 200,000 tonnes. In comparison, production of the conventional oil and natural gas liquids in 2008 amounted 3.95 billion tonnes or .
History of the oil shale industry
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.
A.F.S.K. Hom Tov
In the shale oil extraction process (US Patent 5372708) invented in 1992 by Moshe Gvirtz (also spelled as Moshe Gewertz) and promoted by Hom Tov, oil shale fine particles are slurried with waste bitumen and pumped through coils in a heater. Promoters of this process claimed that the process was profitable at the crude oil price of US$17 per barrel. The company also claimed that the technology was more efficient as it enables the oil shale to be processed at somewhat lower temperatures with the addition of the catalyzing bitumen, and more environmentally friendly than classical shale oil extraction methods. In 2006, in conjunction with announcing the planned partnership with Glazer, the company announced plans to build a full-scale production plant in the Negev Desert south of Beer Sheba at Mishor Rotem. The Mishor Rotem plant would bring bitumen by pipeline from the Ashdod refinery and return product along the same corridor.
Oil shale in Estonia
In June 1916, the Russian geologist Nikolay Pogrebov oversaw mining of the first tonnes of oil shale at Pavandu and delivered it to Saint Petersburg (then Petrograd) Polytechnic Institute for large-scale experiments. These events marking the beginning of the Estonian oil shale industry took place more than half a century after an oil shale industry had emerged in Scotland, the leading oil shale industry in 1916, and a decade before the industry emerged in China, which, besides Estonia, is today the other leading oil shale-exploiting country. In 1916 a total of 640–690 tonnes of oil shale were sent to Saint Petersburg for testing. The tests proved that the oil shale was suitable for combustion as a solid fuel and for extraction of oil shale gas and shale oil. Based on these promising results, a plan for oil shale mining in Estonia was presented to the Emperor Nicholas II on 3 January 1917. On 13 February 1917, the Council of Ministers of Russia allocated 1.2 million rubles to purchase land and start mining activities. After the February Revolution, the Russian Provisional Government appointed a special commissioner for oil shale purchasing and stockpiling who began preliminary work for the digging of an oil shale mine at Pavandu, with full-scale construction carried out by about 500 workers, including war prisoners, in the summer of 1917. After the October Revolution, financing ceased and construction stopped. Two private Saint Petersburg firms, established specially for oil shale mining, Böckel & Co. and Mutschnik & Co., which in the fall of 1916 had begun surface mining at Kukruse and Järve, respectively, also terminated their mining activities in 1917.
Oil shale industry
Oil shale is mined either by traditional underground mining or surface mining techniques. There are several mining methods available, but the common aim of all these methods is to fragment the oil shale deposits in order to enable the transport of shale fragments to a power plant or retorting facility. The main methods of surface mining are "open pit mining" and "strip mining". An important method of sub-surface mining is the "room-and-pillar method". In this method, the material is extracted across a horizontal plane while leaving "pillars" of untouched material to support the roof. These pillars reduce the likelihood of a collapse. Oil shale can also be obtained as a by-product of coal mining.
Nevada–Texas–Utah retort
The heated gas caused a pyrolysis on the lower part of oil shale and produced shale oil and oil-shale gas are escaped from the retort through exhaust pipe at the bottom of retort. The pyrolysis occurred at the temperature about . By time-being, the combustion zones moved downward, and the char (semi-coke) produced as a solid residue of pyrolysis, ignited to burn as additional fuel for combustion. This caused the pyrolysis zone to move downward to the lower parts of retort. After combustion zone reached to the bottom of retort, air injection was stopped to stop combustion. After burning of char, the shale oil production ceased and only spent oil shale ash remained in the retort. The bottom of retort could opened for removal of the oil shale ash after retorting process. Operating the NTU retort with nominal capacity of 40 ton of raw oil shale, the full process cycle took about 40 hours. The shale oil yield varied from 80% to 85% of Fischer assay.
Shale oil extraction
Oil-shale extraction can damage the biological and recreational value of land and the ecosystem in the mining area. Combustion and thermal processing generate waste material. In addition, the atmospheric emissions from oil shale processing and combustion include carbon dioxide, a greenhouse gas. Environmentalists oppose production and usage of oil shale, as it creates even more greenhouse gases than conventional fossil fuels. Experimental "in situ" conversion processes and carbon capture and storage technologies may reduce some of these concerns in the future, but at the same time they may cause other problems, including groundwater pollution. Among the water contaminants commonly associated with oil shale processing are oxygen and nitrogen heterocyclic hydrocarbons. Commonly detected examples include quinoline derivatives, pyridine, and various alkyl homologues of pyridine (picoline, lutidine).
History of the oil shale industry in the United States
The United States Navy and the Office of Naval Petroleum and Oil Shale Reserves started evaluations of oil shale's suitability for military fuels, such as jet fuels, marine fuels and a heavy fuel oil. Shale-oil based JP-4 jet fuel was produced until the early 1990s, when it was replaced with kerosene-based JP-8. Seventeen companies led by Standard Oil of Ohio formed the Paraho Development Corporation to develop the Paraho process. Production started in 1974 but was closed in 1978. In 1974 the United States Department of the Interior announced an oil shale leasing program in the oil shale regions of Colorado and Utah. In 1980 the Synthetic Fuels Corporation was established which operated until 1985.
Oil shale geology
There are varying classifications of oil shales depending on their mineral content, type of kerogen, age, depositional history, and organisms from which they are derived. The age of the known oil shale deposits ranges from Cambrian to Paleogene age. Lithologies comprise shales and marl and carbonate rocks, all of which form a mixture of tightly bound organic matter and inorganic components.
Shale oil extraction
The Illinois Institute of Technology developed the concept of oil shale volumetric heating using radio waves (radio frequency processing) during the late 1970s. This technology was further developed by Lawrence Livermore National Laboratory. Oil shale is heated by vertical electrode arrays. Deeper volumes could be processed at slower heating rates by installations spaced at tens of meters. The concept presumes a radio frequency at which the skin depth is many tens of meters, thereby overcoming the thermal diffusion times needed for conductive heating. Its drawbacks include intensive electrical demand and the possibility that groundwater or char would absorb undue amounts of the energy. Radio frequency processing in conjunction with critical fluids is being developed by Raytheon together with CF Technologies and tested by Schlumberger.
Oil shale geology
Most oil shale deposits were formed during Middle Cambrian, Early and Middle Ordovician, Late Devonian, Late Jurassic, and Paleogene times through burial by sedimentary loading on top of the algal swamp deposits, resulting in conversion of the organic matter to kerogen by diagenetic processes. The largest deposits are found in the remains of large lakes such as the deposits of the Green River Formation of Wyoming and Utah, USA. Oil-shale deposits formed in the shallow seas of continental shelves generally are much thinner than large lake basin deposits.
Kerogen
Kerogen breaks down in the subsurface to generate oil and gas, which form the source of hydrocarbons in conventional reservoirs. In unconventional resources, many of which are referred to as shale, the produced hydrocarbons have not been expelled from the source rock, but instead are stored and transported within the shale. Most kerogens of relevance to the oil and gas industry are marine (). Much of the porosity in shale is hosted within kerogen, and the recent development of economic shale resources has led to increased research into the composition of kerogen. Studies using NMR spectroscopy have found that carbon in kerogen can range from almost entirely aliphatic (sp hybridized) to almost entirely aromatic (sp hybridized). with kerogens of higher type and/or higher thermal maturity typically having higher abundance of aromatic carbon.
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 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.
Synthetic fuels in the United States
Synthetic production of liquid fuels ("i.e.", gasoline and oil substitutes) in the United States has a long history. In the 19th century, dozens facilities produced oil, gas, grease and paraffin from coal, but by 1873, cheap petroleum caused the last coal oil plant to close. The commercial scale shale oil extraction began in 1857 at shale oil retorts retorting the Devonian oil shale along the Ohio River Valley. However, after crude oil discovery in Pennsylvania in 1859, oil shale industries found it difficult to compete and they were shut down by 1861.
History of the oil shale industry
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.
KENTORT II
The pyrolyzed oil shale moves by gravity downward to the gasification section. Gasification, which takes place at to , converts remained carbon in the spent shale (char) to product oil shale gas. Steam from the cooling zone is used for fluidizing the sent shale while heat transferred by hot solids (oil shale ash) from the combustion section. The spent shale moves to the combustion section where it is burnt to heat the process, while oil shale ash moves to the cooling section before its removal from the retort.
Shale oil extraction
The Geothermic Fuels Cells Process (IEP GFC) proposed by Independent Energy Partners extracts shale oil by exploiting a high-temperature stack of fuel cells. The cells, placed in the oil shale formation, are fueled by natural gas during a warm-up period and afterward by oil shale gas generated by its own waste heat.
Oil shale economics
In a 1972 publication by the journal "Pétrole Informations" (ISSN 0755-561X), shale oil production was unfavorably compared to the liquefaction of coal. The article stated that coal liquefaction was less expensive, generated more oil, and created fewer environmental impacts than oil shale extraction. It cited a conversion ratio of of oil per one ton of coal, as against per one ton of shale oil.
Oil shale in Estonia
Shale oil production started in Estonia in 1921 when Riigi Põlevkivitööstus built 14 experimental oil shale processing retorts in Kohtla-Järve. These vertical retorts used the method developed by Julius Pintsch AG that would later evolve into the current Kiviter processing technology. Along with the shale oil extraction plant, an oil shale research laboratory was founded in 1921. Following the experimental retorts, the first commercial shale oil plant was put into operation on 24 December 1924. The German-owned company Eesti Kiviõli (, , predecessor of Kiviõli Keemiatööstus), affiliated with G. Scheel & Co. and Mendelssohn & Co., was established in 1922. By the end of the 1930s, it had become the largest shale oil producer in Estonia. Around the company's mine and oil plant, the Kiviõli settlement (now town) was formed in the same way as the Küttejõu settlement (now district of Kiviõli) formed around the mine owned by Eesti Küttejõud. In 1924, the British investor-owned Estonian Oil Development Syndicate Ltd. (later Vanamõisa Oilfields Ltd.) purchased an open-pit mine in Vanamõisa and opened a shale oil extraction plant that was abandoned in 1931 due to technical problems. The Swedish–Norwegian consortium Eestimaa Õlikonsortsium (, ), controlled by Marcus Wallenberg, was founded in Sillamäe in 1926. New Consolidated Gold Fields Ltd. of the United Kingdom built a shale oil extraction plant at Kohtla-Nõmme in 1931. This facility continued to operate until 1961.