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Oil shale

From Academic Kids

Oil shale is a general term applied to a group of fine black to dark brown shales rich enough in bituminous material (called kerogen) to yield petroleum upon distillation. The kerogen in oil shale can be converted to oil through the chemical process of pyrolysis. During pyrolysis the oil shale is heated to 450-500° C in the absence of air and the kerogen is converted to oil and separated out, a process called "retorting". Oil shale has also been burnt directly as a low-grade fuel. The United States Office of Naval Petroleum and Oil Shale Reserves estimates the world supply of oil shale at 1662 billion barrels of which 1200 billion barrels is in the United States [1] (http://www.eia.doe.gov/oiaf/aeo/conf/pdf/dammer.pdf). Estonia, Russia, Brazil, and China currently mine oil shale, however production is declining due to economic and environmental factors.

Contents

Geology

Oil shale was formed in the distant past by the simultaneous deposit of silt and organic debris on lakebeds and sea bottoms. As the raw materials accumulated, heat and pressure transformed them into a stable mixture of inorganic minerals and solidified organic sludge. However the heat and pressure were not as great as in the similar process that forms petroleum. Oil shale is known as 'the rock that burns'.

Extraction

There are two main methods of extracting oil from shale - surface mining and in-situ.

Mining

With mining, the oil shale is strip-mined from the ground and then transported to a processing facility. There, the shale is heated to 450-500° C, is extra hydrogen added (by combining with superheated steam), and the waste material disposed of.

In-situ

With in-situ processing, the shale is fractured and heated where it is to release gases and oils. Most of these methods are still experimental.

Royal Dutch/Shell has been developing an method using electrical heating in Colorado, some 200 miles (320 km) west of Denver. A heating elements is lowered into a well and allowed to warm the kerogen over time, slowly converting it into oils and gases, which are then pumped to the surface. This greatly reduces the footprint of extraction operations - to no more than a conventional oil well. It could also potentially extract more oil from a given area of land, as the wells can reach much deeper than surface strip-mines can.

History

Oil shale has been used since ancient times and like coal can be used directly as a fuel. The modern use of oil shale to produce oil dates to Scotland in the 1850s. In 1847 Dr James Young prepared lighting oil, lubricating oil and wax from coal. Then he moved his operations to Edinburgh where oil shale deposits were found. In 1850 he patented the process of "cracking" oil into its constituent parts. Oil from oil shale was produced in that region from 1857 until 1962 when production was cancelled due to the much lower cost of petroleum.

Estonia first used oil shale as a low-grade fuel in 1838 after attempts to distill oil from the material failed. However it was not exploited until fuel shortages during World War I. Mining began in 1918 and has continued since, with the size of operation increasing with demand. Two large power stations burning oil shales were opened, a 1,400MW plant in 1965 and a 1,600MW plant in 1973. Oil shale production peaked in 1980 at 31.35 million tonnes. However, in 1981 a nuclear power station opened in the nearby Leningrad region of Russia, reducing demand for Estonian shale. Production gradually decreased until 1995, since when production has increased again albeit only slightly. In 1999 the country used 11 million tonnes of shale in energy production, and plans to cut oil shale's share of primary energy production from 62% to 47-50% in 2010.

Australia mined 4 million tonnes of oil shale between 1862 and 1952, when government support of mining ceased. More recently, from the 1970s on, oil companies have been exploring possible reserves. Since 1995 Southern Pacific Petroleum N.L. and Central Pacific Minerals N.L. (SPP/CPM) (at one time joined by the Canadian company Suncour) has been studying the Stuart Deposit near Gladstone, which has a potential to produce 2.6 billion barrels of oil. From June 2001 through to March 2003, 703,000 barrels of oil, 62,860 barrels of light fuel oil, and 88,040 barrels of ultra-low sulphur naphtha were produced from the Gladstone area. Once heavily processed, the oil produced will be suitable for production of low-emission petrol.

Brazil has produced oil from oil shales since 1935. Small demonstration oil-production plants were built in the 1970s and 1980s, with small-scale production continuing today. China has been mining oil shale to a limited degree since the 1920s near Fushun, but the low price of crude oil has kept production levels down. Russia has been mining its reserves on a small-scale basis since the 1930s.

The United States has seen some attempts at large-scale exploitation. Oil distilled from shale was first burnt for horticultural purposes in the 19th Century, but it was not until the 1900s that larger investigations were made and the Office of Naval Petroleum and Oil Shale Reserves was established in 1912. The reserves were seen as a possible emergency source of fuel for the military, particulary the Navy.

After World War II, the US Bureau of Mines opened a demonstration mine at Anvils Point in Colorado, which operated at a small-scale. It was not until the oil crisis of the 1970s and the US becoming a net importer of oil that efforts at utilization were increased. Military uses were deemed less important and commercial exploitation came to the fore, with several oil companies investing. Several billion dollars were spent until declining oil prices rendered production uneconomical once more and the final company Unocal withdrew in 1991. Currently, there is no oil shale production activity in the US.

Reserves

Estimates vary as to how many barrels of oil are contained in oil shale reserves. The US Office of Naval Petroleum and Oil Shale Reserves are some 1.6 trillion barrels of oil contained in oil shales around the world, with 60-70% of reserves (1.0-1.2 trillion barrels) in the United States. Most US oil shale is concentrated in the Green River Formation in Wyoming, Utah and Colorado. These oil shale resources underlie a total area of 16,000 square miles

Estonia has some five billion tonnes of oil shale reserves.

The Australian Geological Survey Organization estimates that the country has 32-37 billion tonnes of oil shale, equivalent to 220-260 billion barrels of oil.

Canada has 1.7 billion tonnes of oil shale distributed throughout the country.

Germany has reserves equivalent to three billion tonnes of oil.

Economics

Below forty dollars a barrel, oil-shale oil is not competitive with conventional crude oil. If the oil price were to stay permanently at over forty dollars a barrel (with no chance of declining, which could be the case if oil shale were to be exploited on a large enough scale), then companies would exploit oil shale. Generally, the oil shale has to be mined, transported, retorted, and then disposed of, so at least 40% of the energy value is consumed in production. Water is also needed to add hydrogen to the oil-shale oil before it can be shipped to a conventional oil refinery. The largest deposit of oil shale in the United States is in western Colorado (the Green River Shale deposits), a dry region with no surplus water. The oil shale can be ground into a slurry and transported via pipeline to a more suitable pre-refining location.

During the oil crisis of the 1970s, people thought that oil supplies were peaking, expected oil prices to be around seventy dollars a barrel for some time to come, and invested huge amounts of money in refining oil shale — money that they lost. Because of the astronomical sums that were lost last time around there is considerable reluctance to invest in oil shale this time around. Investors are waiting to see if oil prices really will remain this high (in mid-2005: US$50+). Prices are rising because of increased demand in rapidly developing countries, particularly China. Will high prices result in the discovery of more oil, as happened in the seventies, or will alternatives to drilling for oil have to be developed? Investors, burnt badly in the 1980s for their enthusiasm of the seventies, are in no hurry to develop oil shale. Those who lost money then are inclined to believe that more oil will be found by and by.

China is the country suffering most severely from high oil prices. The Chinese government has sponsored a project to extract oil from shale.

Environmental considerations

Surface-mining of oil shale deposits (as would be done if the US reserves were to be exploited) has all the normal environmental effects from open-pit mining, the pre-refining stage to get crude oil generates ash, pipelines must be built to an oil refinery, and the waste rock must be disposed of, rock which is a known carcinogen. Oil shale rock expands by around 30% after processing due to a popcorn effect from the heating; this waste then needs disposal. Oil shale also needs water, which may be in short supply.

All forms of oil shale exploitation is very inefficient as the energy demands of blasting, transporting, crushing, heating the material, and then adding hydrogen, together with the safe disposal of huge quantities of waste material, are large.

Current extraction methods produce four times as much greenhouse gas as does conventional oil production.

See also

References

  1. World Energy Council - Oil shale (http://www.worldenergy.org/wec-geis/publications/reports/ser/shale/shale.asp)
  2. WorldOil.com - Oil shale back in the picture (http://www.worldoil.com/Magazine/MAGAZINE_DETAIL.asp?ART_ID=2378)
  3. - Office of Naval Petroleum and Oil Shale Reserves presentation on oil shale (http://www.eia.doe.gov/oiaf/aeo/conf/pdf/dammer.pdf)
  4. Statement Of Thomas Lonnie Assistant Director for Minerals, Realty & Resource Protection, Bureau of Land Management, U.S. Department of the Interior before the Senate Energy and Natural Resources Committee Oversight Hearing on Oil Shale Development Efforts, Bureau of Land Management, April 12, 2005 (http://www.doi.gov/ocl/2005/OilShaleDev.htm)
  5. Production Optimization: They’re playing the shale card again (http://www.eandpnet.com/ep/previous/0602/0602prod_optimization.htm), Hart's E&P Net, June 2002da:olieskifer

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