Not to be confused with shale oil, which is oil produced via horizontal wells and hydraulic fracturing, oil shale must be heated to high temperatures to convert the organic matter (kerogen) into usable oil.
Shale is a fine-grained sedimentary rock composed of mud containing clays and silt-size particles of other minerals. Some shale can also contain significant amounts (5% or more) of organic matter—the fossil remains of protozoans, microscopic animals, or plants—called kerogen. When kerogen-bearing shale is buried deeply enough and for millions of years, the natural heat and pressure of the Earth can convert the kerogen to oil (and/or gas).
However, in Utah’s oil-shale deposits, much of the kerogen-bearing rock is close to the surface and therefore has not yet generated hydrocarbons. The oil industry has for years attempted to develop economic techniques to artificially “cook” the kerogen, thus speeding up the process from millions of years to days.
Utah’s oil-shale deposits are located in the Uinta Basin of northeastern Utah. The estimated in-ground resources are over 300 billion barrels of oil—some of the largest oil-shale resources in the world.
Utah oil shale was deposited as organic-rich sediments in a freshwater lake (Lake Uinta) about 50 million years ago. These deposits are found exposed around the Uinta Basin’s rim in the Green River Formation—also a major oil and gas producer in the subsurface of the basin. Potential Green River Formation oil shale reserves based on 30 gallons per ton of rock are almost 20 billion barrels of oil.
Currently, only a few companies are pursuing oil shale development in Utah, all focusing on near surface deposits in the southeastern part of the resource.
Survey Notes Articles
Oil Shale vs. Shale Oil: What’s The Difference?
Survey Notes, v. 44 no. 3, September 2012
Exploring Utah’s Other Great Lake
Survey Notes, v. 43 no. 2, May 2011
Energy News: Evaluating Utah’s Oil Shale Resource
Survey Notes, v. 41 no. 1, January 2009
Utah likely to be a key player in future oil shale development
Survey Notes, v.38, no.1., January 2006