Earth oil, Neft or petroleum is comprised of hydrocarbons, denser than water, dark coloured, unrefined, having a speficic odor, and is a combustible mineral oil exploited from the underground. Its name is derived from “petra” meaning rock and “oleum” meaning oil in Latin (Petra oleum=Petroleum)

Although petroleum is known amongst layman as a speficic fuel (Gasoline, Kerosine, Diesel fuel, Engine oil, Fuel oil), in reality petroleum means the crude oil, unprocessed and found in the nature in underground.

Petroleum is occurring as a mixture of hydrocarbons and do not have a fixed chemical composition.
The crude petroleum is a natural fuel and is of varying composition depending on the region of existence. For example; in USA and especially the petroleum produced in Pennsylvania contains in general, hydrocarbon class of components; Russian petroleum contain naften class components with bad odor; Romanian petroleum on the other hand comprise of the mixture these two kinds.
The various kinds of petroleum have specific weights between 0,80 and 0,96; flash points between 15 to 120 °C and average heating strenghts 10,500 cal/kg. The average elemental composition; carbon 84%, hydrogen 12%, oxygen 1% and a trace amount of sulphur. The sulphur content of Texas and California petroleum is higher as compared to the others.
There are a high number of petroleum types that different hydrocarbons of different chemical compositions combine together and compose them (for example: paraphine based petroleum, asphalt based petroleum etc).

Hundreds of millions years ago, the remains of the animal and plant living in the sea or brought by water and deposited in the sea, in an anaerobical medium and required conditions (heat, pressure and microorganism activities) created the kerosene similar to crude oil.The kerosene later on while migrating towards upper layers undergone gradual changes and composed the crude petroleum. Just because of this reason the crude petroleum of none of the fields exactly match the other field’s crude petroleum; definitely there are somewhat differences. Even this situation is frequently observed within the same field.

Chemical Composition

Octane is a hydrocarbon that is found in the petroleum. The lines are covalent tie, the black spheres are carbon and white spheres are the hydrogen.
The chemical composition of the petroleum is comprised of hydrocarbon chains of various lenghts. These chains during the distillation process of the petroleum are separated and the products like; gasoline, jet fuel, kerosene are obtained.