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Fossil oils
Fossil oils are liquid hydrocarbons produced from a buried reservoir through wells (or rarely by mining) to the surface. They can be transported, before or after refining, in liquid form and are used, before or after refining, as fuels and/or in the chemical industry.
Such hydrocarbons include all oils and condensates extracted from oil, oil and gas, and/or gas fields, as well as from dispersed reservoirs; all natural gas liquids; all drilled shale oils from shale and other tight reservoirs; and extra-heavy oils (including bitumens) used for energy before or after conversion to syncrude.
Field oils (or conventional oils) - are defined as hydrocarbon liquids that have been, or will be, extracted, naturally or with artificial lift, through wells from an oil, wet gas, or oil and gas field made up of one or more porous and permeable reservoirs.
The oils, including condensates, can exist naturally as a liquid at the wellhead at surface temperatures and pressures.
Natural gas liquids (NGLs) - are defined as hydrocarbon liquids comprising light oils or condensates that have been, or will be, recovered in a processing plant from associated gases or free gases that have or will be extracted from a field.
Most NGLs are stable at normal temperatures but the NGLs that are synthesised (propane and butane), called Liquefied Petroleum Gases (LPGs), need pressurised containers for storage.
Shale/tight Oils (STOs) - are defined as hydrocarbon liquids that have been, or will be, extracted through wells, naturally or with artificial lift, from tight , non-field, dispersed reservoirs (including shales, sandstones or carbonates) before or after underground artificial fracturing.
They should not be confused with Mined Shale Oils (see below).
Extra-heavy oils (from oil sands) - are defined as hydrocarbon liquids including bitumens that have been, or will be, extracted from shallow oil sands (also known as tar sands) through wells (usually with steam), or by mining.
They may be converted to syncrude by chemical processes, making them more convenient to transport and burn.
Manufactured oils
Manufactured oils are synthetic liquid hydrocarbons (not including syncrude made from oils from oil sands), with the same characteristics and used for the same purpose as fossil liquid hydrocarbons.
They are oils created through chemical conversion processes from gas, from coal, from shale, and from biomass (bioethanol and biodiesel).
Mined shale oils - are defined as hydrocarbon liquids that have been, or will be, made after heating and processing shale rock (retorting), that has been extracted from the earth by mining, in a surface industrial plant.
Gas-to-liquids (GTLs) - are defined as hydrocarbon liquids that have been, or will be, made in a refinery by converting natural gaseous hydrocarbons into longer-chain gasoline or diesel fuel via direct conversion or via syngas as an intermediate.
The Fischer-Tropsch and Mobil processes are the most commonly used methods.
Coal-to-liquids (CTLs) - are defined as hydrocarbon liquids that have been, or will be, made by coal liquefaction (mainly using the Fischer-Tropsch process).
Coal is gasified to make syngas and catalysts then convert the syngas into light hydrocarbons which are processed into gasoline and diesel.
Biomass-to-liquids (BTLs) - are defined as hydrocarbon liquids that have been, or will be, made from plant materials rather than petroleum products. They do not include biomass solids which are agricultural crops and residue, wood and wood waste, animal waste, aquatic plants and the organic components of municipal and industrial wastes.
Biodiesel BTLs are created when plant oils are combined with alcohol in the presence of a catalyst to form ethyl or methyl ester.
Ethanol BTLs are formed during sugar fermentation by yeast of plants, including cellusosic ethanol which is created directly from woody biomass.
Gains (in a refinery) - are defined as liquid hydrocarbons that have been, or will be, created during refining. The processing of oil and the associated chemical changes increase the volume by a few percent, depending on the input oil and the selected refinery output.
They are not geographically subdivided in the analyses.
Other criteria
Onshore production
Includes oils from onshore wells, including those drilled in lakes, swamps and on piers, regardless of subsurface location.
Oils from oil sands and manufactured oils are assumed to be onshore (although gas feedstocks may originate from offshore locations).
Offshore production
Includes oils from offshore wells, including those drilled from fixed platforms and artificial islands unconnected to the mainland.
Water depths
Very shallow waters
Areas of oil and/or gas output from reservoirs beneath marine waters from greater than 0m down to 100m.
Medium shallow waters
Areas of oil and/or gas output from reservoirs beneath marine waters from greater than 100m down to 500m.
Medium deep waters
Areas of oil and/or gas output from reservoirs beneath marine waters from greater than 500m down to 1000m.
Very deep waters
Areas of oil and/or gas output from reservoirs beneath marine water depths from greater than 1000m down to 2000m.
Ultra deep waters
Areas of oil and/or gas output from reservoirs beneath marine waters greater than 2000m.
API Gravity
The American Petroleum Institute (API) term to express the specific weight of oils, computed as (141.5/specific gravity) - 131.5, where the specific gravity of the oil is at 60°F. The lower the specific gravity value, the higher the API gravity.
Light oils
Have an API gravity of over 22° and a viscosity of less than 100 centipoise (cp).
Heavy oils
Dense, viscous oils with asphaltene, usually containing impurities such as sulphur, heavy metals, waxes and carbon residue that must be removed before refining. The upper limit for heavy oils is taken as 22° API, the lower limit 10° API gravity.
Extra-heavy oils
The portion of heavy oils having an API gravity of less than 10° (including bitumens), which are dense and viscous with a viscosity greater than 10,000 cp. Negligible extra-heavy oil is produced offshore.
