An oil refinery or petroleum refinery is an industrial process plant where crude oil is transformed and refined into useful products such as petroleum naphtha, gasoline, diesel fuel, asphalt base, heating oil, kerosene, liquefied petroleum gas, jet fuel and fuel oils. Petrochemicals feedstock like ethylene and propylene can also be produced directly by cracking crude oil without the need of using refined products of crude oil such as naphtha. The crude oil feedstock has typically been processed by an oil production plant. There is usually an oil depot at or near an oil refinery for the storage of incoming crude oil feedstock as well as bulk liquid products. According to the Oil and Gas Journal, on 31 December 2014, a total of 636 refineries operated worldwide with a total daily capacity of 87.75 million barrels (13,951,000 m3).

Oil refineries are typically large, sprawling industrial complexes with extensive piping running throughout, carrying streams of fluids between large chemical processing units, such as distillation columns. In many ways, oil refineries use much of the technology and can be thought of, as types of chemical plants. Jamnagar Refinery is the largest oil refinery, since 25 December 2008, with a processing capacity of 1.24 million barrels (197,000 m3). In Gujarat, India, it is owned by Reliance Industries. Some modern petroleum refineries process as much as 800,000 to 900,000 barrels (12,000 to 143,000 m3) of crude oil per day.

An oil refinery is considered an essential part of the downstream side of the petroleum industry.

 

Note:   The above text is excerpted from the Wikipedia article Oil refinery, which has been released under the GNU Free Documentation License.