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G e n e r a l n o t e s
Definitions
Proven reserves: an estimated quantity of all hydrocarbons statistically defined as crude oil or natural gas, which geological and engineer-
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ing data demonstrate with reasonable certainty to be recoverable in future years from known reservoirs under existing economic and
operating conditions. Reservoirs are considered proven if economic producibility is supported by either actual production or conclusive
formation testing. The area of an oil reservoir considered proven includes those portions delineated by drilling and defined by
gas-oil or oil-water contacts, if any, and the immediately adjoining portions not yet drilled, but which can be reasonably judged as
economically productive on the basis of available geological and engineering data. In the absence of information on fluid contacts,
the lowest known structural occurrence of hydrocarbons controls the lower proven limit of the reservoir.
Crude oil: estimates include oil that can be produced economically through application of improved recovery techniques following
successful completion of pilot testing. Estimates do not include:
• oil that may become available from known reservoirs but is reported separately as ‘indicated additional reserves’;
• oil, the recovery of which is subject to reasonable doubt because of uncertainty as to geology, reservoir characteristics or economic
factors;
• oil that may occur in untested prospects; and
• oil that may be recovered from oil shales, coal, gilsonite and other such sources.
Natural gas: estimates are prepared for total recoverable natural gas, non-associated gas and associated-dissolved gas. Estimates
do not include gaseous equivalence of natural gas liquids expected to be recovered from reservoir natural gas as it is produced,
natural gas being held in underground storage or non-hydrocarbon gases.
Rig: a derrick complete with engine-house and other equipment necessary for drilling oil and gas wells.
Well (exploratory and development): a hole drilled for the purpose of finding or producing crude oil or natural gas; or providing
services related to the production of crude oil and natural gas.
Completion: this term refers to the installation of permanent equipment for the production of oil or gas.
Oil or gas well: a well completed for the production of oil or gas from one or more zones or reservoirs.
Dry hole: a well found to be incapable of producing either oil or gas in sufficient quantities to justify completion as an oil or gas
well.
Crude oil: a mixture of hydrocarbons that exists in a liquid phase in natural underground reservoirs and remains liquid at atmospheric pressure
after passing through surface separating facilities. Production volumes reported as crude oil include:
• liquids technically defined as crude oil;
• small amounts of hydrocarbons that exist in the gaseous phase in natural underground reservoirs, but which are liquid at atmospheric
pressure after being recovered from oil well (casing head) gas in lease separators;
• small amounts of non-hydrocarbons produced with the oil.
Natural gas liquids (NGLs): those reservoir gases liquefied at the surface in lease separators, field facilities or gas processing plants. NGLs
consist of field condensates and natural gas plant products such as ethane, pentane, propane, butane and natural gasoline.
Natural gas: a mixture of hydrocarbon compounds and small quantities of various non-hydrocarbons existing in the gaseous phase or in
solution with oil in natural underground reservoirs at reservoir conditions. The natural gas volumes in this Bulletin refer to Standard
Conditions of 60o F, 14.73 psia (15.6o C, 760 mm/Hg).
Gross production: the total flow of natural gas from oil and gas reservoirs of associated-dissolved and non-associated gas.
Marketed production: corresponds to gross production, minus the volumes of gas flared or re-injected into fields, minus the shrinkage.
Re-injection: the total volume of natural gas produced from oil and gas completions, processed through gas-processing plants and
field facilities, and used for gas lift, gas injection, and cycling operations.
Shrinkage: contraction due to natural gas processing, purification for the extraction of natural gas liquids.
Flared: total volume of vented or flared gas.
Refinery capacity (operable): the maximum amount of input to crude oil distillation units that can be processed in an average 24-hour
period.
Barrels per calendar day (b/cd): the total number of barrels processed in a refinery within a year, divided by 365 days, thus reflecting
all operational limitations.
Barrels per stream day (b/sd): the number of barrels of input that a refining facility can process within 24 hours, operating at full capacity
under optimal crude and product slate conditions.