Understanding Oil Shale 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.

China (Manchuria), Estonia, New Zealand, South Africa, Spain, Sweden, and Switzerland began extracting shale oil in the early 20th century. However, crude oil discoveries in Texas during the 1920s and in the Middle East in the mid 20th century brought most oil shale industries to a halt.

In 1944, the US recommenced shale oil extraction as part of its Synthetic Liquid Fuels Program. These industries continued until oil prices fell sharply in the 1980s. The last oil shale retort in the US, operated by Unocal Corporation, closed in 1991. The US program was restarted in 2003, followed by a commercial leasing program in 2005 permitting the extraction of oil shale and oil sands on federal lands in accordance with the Energy Policy Act of 2005.

As of 2010, shale oil extraction is in operation in Estonia, Brazil, and China. In 2008, their industries produced about 930,000 metric tonnes  (17,700 barrels per day) of shale oil. Australia, the US, and Canada have tested shale oil extraction techniques via demonstration projects and are planning commercial implementation; Morocco and Jordan  have announced their intent to do the same. Only four processes are in commercial use: Kiviter, Galoter, Fushun, and Petrosix .

What is Oil Shale

The term oil shale generally refers to any sedimentary rock that contains solid bituminous materials (called kerogen) that are released as petroleum-like liquids when the rock is heated in the chemical process of pyrolysis. Oil shale was formed millions of years ago by deposition of silt and organic debris on lake beds and sea bottoms.

Over long periods of time, heat and pressure transformed the materials into oil shale in a process similar to the process that forms oil; however, the heat and pressure were not as great. Oil shale generally contains enough oil that it will burn without any additional processing, and it is known as “the rock that burns”.

Oil shale

Oil shale can be mined and processed to generate oil similar to oil pumped from conventional oil wells; however, extracting oil from oil shale is more complex than conventional oil recovery and currently is more expensive. The oil substances in oil shale are solid and cannot be pumped directly out of the ground.

The oil shale must first be mined and then heated to a high temperature – a process called retorting; the resultant liquid must then be separated and collected. An alternative but currently experimental process referred to as in situ retorting involves heating the oil shale while it is still underground, and then pumping the resulting liquid to the surface.

The Oil Shale Industry

While oil shale has been used as fuel and as a source of oil in small quantities for many years, few countries currently produce oil from oil shale on a significant commercial level. Many countries do not have significant oil shale resources, but in those countries that do have significant oil shale resources, the oil shale industry has not developed because historically, the cost of oil derived from oil shale has been significantly higher than conventional pumped oil. The lack of commercial viability of oil shale-derived oil has in turn inhibited the development of better technologies that might reduce its cost.

Relatively high prices for conventional oil in the 1970s and 1980s stimulated interest and some development of better oil shale technology, but oil prices eventually fell, and major research and development activities largely ceased. More recently, prices for crude oil have again risen to levels that may make oil shale-based oil production commercially viable, and both governments and industry are interested in pursuing the development of oil shale as an alternative to conventional oil.

Oil Shale Mining and Processing

Oil shale can be mined using one of two methods: underground mining using the room-and-pillar method or surface mining. After mining, the oil shale is transported to a facility for retorting, a heating process that separates the oil fractions of oil shale from the mineral fraction. The vessel in which retorting takes place is known as a retort. After retorting, the oil must be upgraded by further processing before it can be sent to a refinery, and the spent shale must be disposed of. Spent shale may be disposed of in surface impoundments, or as fill in graded areas; it may also be disposed of in previously mined areas.

Eventually, the mined land is reclaimed. Both mining and processing of oil shale involve a variety of environmental impacts, such as global warming and greenhouse gas emissions, disturbance of mined land, disposal of spent shale, use of water resources, and impacts on air and water quality.

The development of a commercial oil shale industry would also have significant social and economic impacts on local communities. Other impediments to development of the oil shale industry include the relatively high cost of producing oil from oil shale, and the lack of regulations to lease oil shale.

Surface Retorting

While current technologies are adequate for oil shale mining, the technology for surface retorting has not been successfully applied at a commercially viable level even in the United States, although technical viability has been demonstrated. Further development and testing of surface retorting technology is needed before the method is likely to succeed on a commercial scale.

In Situ Retorting

Shell Oil is currently developing an in situ conversion process (ICP). The process involves heating underground oil shale, using electric heaters placed in deep vertical holes drilled through a section of oil shale. The volume of oil shale is heated over a period of two to three years, until it reaches 650–700 °F, at which point oil is released from the shale. The released product is gathered in collection wells positioned within the heated zone.

Shell’s current plan involves use of ground-freezing technology to establish an underground barrier called a “freeze wall” around the perimeter of the extraction zone. The freeze wall is created by pumping refrigerated fluid through a series of wells drilled around the extraction zone. The freeze wall prevents groundwater from entering the extraction zone, and keeps hydrocarbons and other products generated by the in-situ retorting from leaving the project perimeter.

Shell’s process is currently unproven at a commercial scale, but is regarded by the U.S. Department of Energy as a very promising technology. Confirmation of the technical feasibility of the concept, however, hinges on the resolution of two major technical issues: controlling groundwater during production and preventing subsurface environmental problems, including groundwater impacts.


Both mining and processing of oil shale involve a variety of environmental impacts, such as global warming and greenhouse gas emissions, disturbance of mined land; impacts on wildlife and air and water quality. The development of a commercial oil shale industry as earlier stated would also have significant social and economic impacts on local communities.

Of special concern in relatively arid regions is the large amount of water required for oil shale processing; currently, oil shale extraction and processing require several barrels of water for each barrel of oil produced, though some of the water can be recycled.

Technology minister commends Shell, others at Science Fair

The Minister of Communication Technology, Ms. Omobola Johnson, recently commended Intel Corporation, and Shell Petroleum Development Company, SPDC, for their support towards redirecting the objectives of educational development from knowledge based to empowerment.

The minister gave the commendation at the 2013 Annual National Science and Engineering Fair, which held at the University of Lagos. She also noted that the decision of the firms to bankroll the fair would further boost the study of Science and Technology in the country.

Activities to mark the four-day event included Science Quiz and exhibition showcase. The exhibition stage saw the competing schools pass their innovative inventions through several stages under the keen watch of panel of judges. The fair was jointly sponsored by Intel Corporation, Shell and Interswitch.

While applauding the participating students, the minister, represented at the occasion by the Director General of Nigerian Postal Services, NIPOST, Mr. Lawrence Okoro, stated that it was expedient that students at that level developed interests in practical sciences and engineering solutions to challenge changes in their environment and the nation as a whole.

Head, Social Performance, SPDC, Mr. Emmanuel Anyim, disclosed that the partnership with Intel and Interswitch was part of the Shell’s commitment to national development, aimed at actively positioning the Nigerian educational sector on a global pedestal.

Ayim said: “Science is key to the development of any country and we feel that the best way to begin is to encourage young talents by exposing them to global standards. And we are happy that the young scientists are rising to the challenge already.”

Also commenting, the spokesman for Intel Corporation, Mr. Osagie Ogunbor, said the partnership with Shell is pursuing a transformation agenda in the educational sector, to encourage a more practical approach to learning, and make students become pragmatic researchers rather than passive receivers of knowledge.

“The changing trends in the global economy are increasingly becoming knowledge-based being driven by advancements in Information and Communication Technology and this has significantly raised the stakes in the educational sector, thus we want to encourage a practical approach that will excite these young minds and spur their appreciation and effective contribution at the student-teacher level and, ultimately add to their wealth of knowledge in their respective disciplines.” Ogunbor noted.

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