American Petroleum Institute

API gravity
The industry standard method of expressing specific gravity of crude oils. Higher API gravities mean lower specific gravity and lighter oils.

Associated gas
Gas occurring in combination with crude oil, as distinct from gas occurring separately or manufactured from crude oil.

American Society for Testing Material which establishes many of the technical standards used in the oil industry


A measurement used in the oil industry for a unit of volume of oil or oil products equivalent to 158.978 litres or 42 US gallons. Abbreviated to “bbl”.

Barrels per day
A unit of measurement used in the industry for the production rates of oil fields, pipelines, and transportation. Abbreviated to “bpd”, “b/d” or “bbl/d”.

Barrels per calendar day
Industry measurement of actual refinery throughput as opposed to designed capacity. Derived by dividing the number of refined barrels of oil by the actual number of days the refinery was in operation. Abbreviated to “b/cd”.

“Black” oil
Crude oil or heavy fuel oil from the bottom of the refining process as opposed to “white” oil.


Catalytic Cracking
Refinery process using a catalyst whereby heavy heavy gas oil is converted to about 50% gasoline and 50% gases and gas oil for recycling.

A term used to describe light liquid hydrocarbons separated from crude oil after production and sold separately.

Refinery process whereby large, heavy, complex hydrocarbon molecules are broken down into simpler and lighter molecules in order to derive a variety of fuel products.

Crude oil
A mineral oil consisting of a mixture of hydrocarbons of natural origin, yellow to black in colour, of variable specific gravity and viscosity


The first stage in the refining process in which crude oil is heated and unfinished petroleum products are initially separated.

The oil industry term used to refer to all petroleum activities from the processing of refining crude oil into petroleum products to the distribution, marketing, and shipping of the products. The opposite of downstream is upstream .


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Fuel oils
Oil that is heavy-distilled in the refining process. Frequently used for supplying energy to power stations and factories.


Gas oil
A medium-distilled oil from the refining process. Often used in diesel fuel.


Compounds containing only the hydrogen and carbon atoms. May be in solid, liquid or gaseous form.

High pressure version of catalytic cracking in the presence of hydrogen.


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Liquified natural gas (LNG)
Natural gas liquified either by refrigeration or by by pressure.

Liquified petroleum gas (LPG)
A mixture of butane, propane and other light hydrocarbons derived from refining crude oil. At normal temperature it is a gas but it can be cooled or subjected to pressure to facilitate storage and transportation.


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Natural gas
Petroleum in gaseous form consisting of light hydrocarbons often found in association with oil. Methane is the most dominant component.


Term used to describe a company appointed by venture stake holders to take primary responsibility for day-to-day operations for a specific plant or activity.


Chemicals such as ethylene, propylene and benzene that are derived from petroleum

Refining process which uses low temperature reforming to increase the octane value of gasoline

Pour point
The ability of crude oil to flow at low temperatures.


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Refining is the process of converting crude oil into usable fuel products. A full description of refining and refining processes is available.

Refining margins
Refining margins are the difference in value between the products produced by a refinery and the value of the crude oil used to produce them. Refining margins will thus vary from refinery to refinery and depend on the price and characteristics of the crude used.

Refinery process aimed at improving gasoline quality by changing chemical characteristics rather than breaking up molecules as in cracking.

An economically recoverable quantity of crude oil or gas.


South African Bureau of Standards

Sour crude oil
Crude oil with a high sulphur content.

Specific gravity
A measure of thedensity of a material usually obtained by comparing it with water.

Sweet crude oil
Crude oil with a low sulphur content.

Synthetically petroleum products produced from coal, or natural gas.


Plant and equipment designed to receive and process crude oil or gas to remove water and impurities.

The primary distillation phase of a refinery process, and by derivation, the type of refinery and its yield of products

The total amount of raw materials processed by a refinery or other plant in a given period.


The processes of exploring for oil; developing oil fields; and producing oil from the oil fields. The opposite of upstream is downstream.


The resistance to flow


“White” oil
Lighter products from the top end of the refining process as distinct from ‘black” oil.

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