Petroleum refining converts crude oil into more useful products like fuels and petrochemicals. Pure crude burns quickly and leaves behind unwanted residue. Thus the oil needs to be separated and treated before use.
Fossil fuels are made up of dead plants and animals buried beween rock layers and heated by the earth to form crude oil. Through exploration and production, the crude oil is discovered and pumped out of the earth into tankers and pipleines and delivered to the refinery. During the refining process, these hydrocarbons are heated and separated by distillation or fracturing. The resulting hydrocarbon molecules (fractions) often are further treated to change their size or structure, which makes them more usable. Products made from refined crude include gasoline, diesel, kerosene, coke, asphalt, petrochemical feedstock, and lubricants, among others.