petroleum, oily, flammable liquid that occurs naturally in deposits, usually beneath the surface of the earth; it is also called crude oil. It consists principally of a mixture of hydrocarbons, with traces of various nitrogenous and sulfurous compounds.
Sections in this article:
- Composition and Refining of Petroleum
- History and Development of Petroleum
- Origin and Natural Occurrence
- Exploration and Drilling of Wells
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