Oil, one of the main objects of the geological exploration, is a thick, dark brown liquid, known as "the blood industry". Oil parts of upper crust. Main ingredient is a mixture of alkanes, cycloalkanes, aromatic hydrocarbons. Petroleum oil forming mechanism of a biological deposit oil and petrochemical oil theories, the former is more widely accepted, that oil is an ancient sea creatures in Lakes after a long evolution, biological sediment changing oil, non-renewable; the latter think that oil is generated by the carbon itself within the Earth's crust, has nothing to do with biological and renewable. Oil is primarily used as a fuel and gasoline and many chemical products, solvents, fertilizers, pesticides, and plastics raw materials.
 in ancient Egypt, the ancient Babylonians in exploitation of oil long ago. "Oil" this name was first named by Northern Song dynasty scientist Shen Kuo.
Properties vary depending on the origin of the oil, the density is 0.8-1.0g/cm3, a wide range of viscosity, freezing point varies (30-60 degrees), boiling point range from room temperature to 500 degrees Celsius, which is soluble in many organic solvents, insoluble in water, but can be used with water to form emulsions. But different composition of oil fields and the appearance can be distinguished. Oil is primarily used as a fuel and gasoline, fuel oil and gasoline by 2012 make up one of the world's most important secondary energy. Oil is many chemical products, including solvents, fertilizers, pesticides, and plastics raw materials. Of 2012 oil 88% is used as a fuel, other 12% as raw material for chemical industry. In fact, oil is a nonrenewable raw materials.
World Ocean area of 360 million square kilometers, about 2.4 times the land. Continental shelf and continental slope of approximately 55 million square kilometers, equivalent to the total areas of land of sedimentary basins. Proven oil resources of the planet 1/4 and ultimate recoverable reserves of 45%, buried on the ocean floor. Contains the center of gravity of the world proven oil reserves, will gradually shift from land to sea.