The concept of oil shale, the requisites for a sedimentary rock to be considered
an oil shale and the distribution and typification of the main oil shale deposits
worldwide are addressed in this chapter. As the chapter forms part of a volume devoted
to the contribution of organic petrology to the study of conventional and unconventional
hydrocarbon resources a significant part is devoted to the petrographic
characteristics of oil shales and the difficulties involved in their analysis. In particular
aspects related to the quantification of organic components, and the level of maturation
have been covered in detail. At present, only a few countries are commercially exploiting
oil shales both as fuel to be burned and as a means to obtain shale oil. However
the reserves are huge and emerging technologies such as in-situ recovery processes are
being tested. The volatility of oil prices and the need to secure energy sources have
been the driving force behind this re-evaluation and characterization of little known oil
shale deposits in recent years, which will hopefully contribute to a revival of scientific
and political interest in oil shale research.
Keywords: Oil shale, Shale oil, Vitrinite reflectance suppression, Fluorescence
variability.
