Characteristics of Oil Shale as Unconventional Oil Resources

Oil shale is a sedimentary rock that contains organic compounds called kerogen that are released as petroleum-like liquids by retorting. In order to evalute oil shale as alternative oil resources, the physical properties of oil shale samples from US and Russia were investigated and Fischer assays were carried out. Thermogravimetric analysis shows that thermal degradation of oil shale consisted of two stage processes, with hydrocarbon release from kerogen followed by release by carbonate decomposition. Organic compounds in oil shale have an high hydrogen/carbon ratio, and therefore liquid hydrocarbons could be obtained easily. Shale oil yields from Russian and US oil shales by Fischer assay were 12.7% and 18.5%, respectively. The density and boiling point of shale oils are higher than that of Middle East crude oil, indicating that further upgrading processes are necessary for refinery. On the other hands, sulfur contents are relatively low, and the amounts of Vanadium and Nickel are extremely small in shale oil. It was found that paraffins were rich in US shale oil while main components of Russian shale oil were oxygenated hydrocarbons.