Shale oil
Unconventional oil derived from oil shale via thermal processing.
Shale oil is a type of unconventional oil made by heating, adding hydrogen, or dissolving oil shale rock fragments. These processes transform kerogen, the organic material in the rock, into synthetic oil and gas. The resulting oil can be burned as fuel or refined further by adding hydrogen and removing sulfur and nitrogen to meet refinery standards. Refined products from shale oil serve the same purposes as those from crude oil. The term "shale oil" can also refer to crude oil extracted from very low-permeability shale formations, but to avoid confusion, "tight oil" or "light tight oil" is the preferred term.
Oil shale was among the earliest mineral oil sources used by humans. In the 10th century, the Arabic physician Masawaih al-Mardini described extracting oil from a type of bituminous shale. It was reportedly used in Switzerland and Austria in the early 14th century. In 1596, the personal physician of Frederick I, Duke of Württemberg, wrote about its healing properties. At the turn of the 18th century, shale oil lit the streets of Modena, Italy. In 1694, the British Crown granted a patent to three people who had found a way to extract pitch, tar, and oil from stone. The distilled product, later sold as Betton's British Oil, was claimed to relieve aches and pains. Modern shale oil industries emerged in France in the 1830s and in Scotland in the 1840s, where the oil was used as fuel, lubricant, and lamp oil, driven by demand from the Industrial Revolution and as a substitute for expensive whale oil. In the late 19th century, extraction plants were built in Australia, Brazil, and the United States. In the early 20th century, China, Estonia, New Zealand, South Africa, Spain, Sweden, and Switzerland also produced shale oil. The discovery of Middle Eastern crude oil in the mid-20th century halted most of these industries, though Estonia and Northeast China continued into the early 21st century. Rising petroleum prices at the turn of the 21st century led to renewed or new extraction operations in the United States, China, Australia, and Jordan.
Shale oil is extracted through pyrolysis, hydrogenation, or thermal dissolution. Pyrolysis occurs in a retort, either above ground or within the rock formation. As of 2008, most industries mine, crush, and transport the rock to a retorting facility, though some experimental technologies process it in place. The temperat
- first described
- 10th century
- early extraction patent
- 1694
- modern industry established
- 1830s (France), 1840s (Scotland)
- key processes
- pyrolysis, hydrogenation, thermal dissolution
- typical EROEI range
- 0.7–13.3 (1984 study); 1–2:1 or 2–16:1 (more recent)
- carcinogen classification
- Group 1 (World Health Organization)
- major global producers (yield examples)
- Fushun Mining Group (4.5% by weight), VKG Oil (13%), Petrobras (9%)
Lore & Background
Oil shale was one of the earliest sources of mineral oil used by humans. In the 10th century, the Arabic physician Masawaih al-Mardini described a method of extracting oil from 'some kind of bituminous shale.' It was used in Switzerland and Austria in the early 14th century, and in 1596 the personal physician of Frederick I, Duke of Württemberg wrote of its healing properties. Shale oil lit the streets of Modena, Italy at the turn of the 18th century. The British Crown granted a patent in 1694 to three persons who had 'found a way to extract and make great quantities of pitch, tarr and oyle out of a sort of stone.' The product, later sold as Betton's British Oil, was said to have been tried by diverse persons in aches and pains with much benefit.
Reader's Guide
Shale oil extraction has a long history, with modern industries emerging in France during the 1830s and Scotland during the 1840s, where the oil was used as fuel, lubricant, and lamp oil, substituting for increasingly scarce whale oil. By the late 19th century, plants were built in Australia, Brazil, and the United States, and in the early 20th century in China, Estonia, New Zealand, South Africa, Spain, Sweden, and Switzerland. The discovery of Middle Eastern crude oil in the mid-20th century halted most operations, though Estonia and Northeast China continued into the early 21st century. Rising petroleum prices at the turn of the 21st century revived extraction in the United States, China, Australia, and Jordan. The viability of extraction is measured by Energy Returned on Energy Invested (EROEI), with estimates varying widely. Shale oil contains polycyclic aromatic hydrocarbons, which are carcinogenic; the World Health Organization classifies it as a Group 1 carcinogen. Upgrading processes such as hydrodesulfurization and hydrodenitrogenation can produce a product comparable to benchmark crude oil.
Did You Know?
- Shale oil was used to light the streets of Modena, Italy at the turn of the 18th century.
- The British Crown granted a patent in 1694 for extracting 'pitch, tarr and oyle' from stone.
- The World Health Organization classifies shale oil as a Group 1 carcinogen to humans.
- A 1984 study estimated the EROEI of oil-shale deposits as varying between 0.7 and 13.3.
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