Introduction of Oil: Oil is otherwise known as crude oil. It occurs naturally underground. Oil is also meaning rock oil. The term petroleum is a generic name applied to deposits of petroleum materials. Oil is found underground. It is a flammable liquid and composed mainly of various hydrocarbons and its average composition is c 80-87%, H 11-15%, S 0.1-4%, N and O 0.1-0.55. The formation of PetroleumPetroleum is evident from chromatographic, spectroscopic, and analytical studies of the presence of a wide variety of organic and inorganic compounds in petroleum. The following are the common constituents present in petroleum. In the formation of petroleum hydrocarbon: main constituents (almost 70%); normal, branched and cycloalkanes are present; alkylbenzenes present in the lower boiling point fractions; the higher boiling fractions contain polynuclear aromatics such as naphthalenes; terpenes are present to a lesser extent and explain the high specific rotations of petroleum distillates. Sulfur-containing compounds: in the formation of petroleum, present as org...