Short answers, pulled from the story.
Oil shale is an organic-rich sedimentary rock containing kerogen, a solid mixture of organic compounds that has not yet transformed into petroleum. Shale oil is the liquid hydrocarbon produced by heating oil shale through pyrolysis. Tight oil, also sometimes called shale oil, is conventional petroleum extracted from oil-bearing shale formations like the Bakken Formation and should not be confused with shale oil derived from oil shale.
A 2016 estimate placed the total world oil shale resources at the equivalent of 6.05 trillion barrels of oil. The United States holds more than 80% of that total, primarily in the Green River Formation spanning Colorado, Utah, and Wyoming. By comparison, the world's proven conventional oil reserves were estimated at 1.6976 trillion barrels at the same time.
Estonia and China have the most established oil shale industries. Brazil, Germany, and Russia utilize oil shale to a lesser extent. As of recent figures, Estonia alone accounts for roughly 80% of global oil shale extraction, primarily because of its oil-shale-fired power plants with a combined installed capacity of 2,967 megawatts.
Humans have used oil shale since prehistoric times. Around 3000 BC, the people of Mesopotamia used "rock oil" for road construction and architectural adhesives. Modern industrial mining began in 1837 in Autun, France, with Scotland, Germany, and other countries following. The first patent for extracting oil from oil shale was British Crown Patent 330, granted in 1694 to Martin Eele, Thomas Hancock, and William Portlock.
On the 2nd of May 1982, Exxon canceled its 5 billion dollar Colony Shale Oil Project near Parachute, Colorado, due to low oil prices and escalating costs. The cancellation, called "Black Sunday" in some circles, laid off more than 2,000 workers and triggered widespread home foreclosures and small business bankruptcies in the surrounding area.
Oil shale extraction raises concerns including acid drainage, introduction of metals such as mercury into surface and groundwater, increased erosion, sulfur-gas emissions, and air pollution from particulates. Above-ground retorting uses one to five barrels of water per barrel of shale oil produced. Greenhouse gas emissions from oil shale processing exceed those of conventional fossil fuels.