| Key Terms |
Definition |
| Acquisitions |
The volume of proved reserves gained by the purchase of an existing fields or properties,
from the date of purchase or transfer.
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| Adjustments |
The quantity which preserves an exact annual reserves balance within each State or State
subdivision of the following form:
Adjustments + Revision Increases - Revision Decreases - Sales + Acquisitions + Extensions and Discoveries - Report Year Production =
Published Proved Reserves at End of Report Year
These adjustments are the yearly changes in the published reserve estimates that cannot be
attributed to the estimates for other reserve change categories because of the survey and
statistical estimation methods employed. For example, variations as a result of changes in
the operator frame, different random samples or imputations for missing or unreported reserve
changes, could contribute to adjustments.
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| Crude Oil |
A mixture of hydrocarbons that exists in liquid phase in natural underground reservoirs and remains
liquid at atmospheric pressure after passing through surface separating facilities. Depending upon
the characteristics of the crude stream, it may also include:
Small amounts of hydrocarbons that exist in gaseous phase in natural underground reservoirs but are
liquid at atmospheric pressure after being recovered from oil well (casinghead) gas in lease
separators and are subsequently commingled with the crude stream without being separately measured.
Lease condensate recovered as a liquid from natural gas wells in lease or field separation facilities
and later mixed into the crude stream is also included;
Small amounts of nonhydrocarbons produced with the oil, such as sulfur and various metals;
Drip gases, and liquid hydrocarbons produced from tar sands, gilsonite, and oil shale.
Liquids produced at natural gas processing plants are excluded. Crude oil is refined to produce a
wide array of petroleum products, including heating oils; gasoline, diesel and jet fuels; lubricants;
asphalt; ethane, propane, and butane; and many other products used for their energy or chemical content.
|
| Extensions and Discoveries |
Additions to a county's proved reserves that result from (1) extension of the proved acreage of previously discovered (old) reserves through additional drilling in periods subsequent to discovery and (2) discovery of new fields with proved reserves or of new reservoirs of proved reserves in old fields.
|
| Extensions |
The reserves credited to a reservoir because of enlargement of its proved area.
Normally the ultimate size of newly discovered fields, or newly discovered reservoirs
in old fields, is determined by wells drilled in years subsequent to discovery. When
such wells add to the proved area of a previously discovered reservoir, the increase
in proved reserves is classified as an extension.
|
| Lease Condensate |
A mixture consisting primarily of pentanes and heavier hydrocarbons which is recovered as a
liquid from natural gas in lease separation facilities. This category excludes natural gas plant
liquids, such as butane and propane, which are recovered at downstream natural gas processing
plants or facilities.
|
| New Field Discoveries |
The volumes of proved reserves of crude oil, natural gas and/or natural gas liquids
discovered in new fields during the report year.
|
| New Reservoir Discoveries in Old Fields |
The volumes of proved reserves of crude oil, natural gas, and/or natural gas liquids
discovered during the report year in new reservoir(s) located in old fields.
|
| Proved Reserves |
Proved reserves of natural gas as of December 31 of the report year are the estimated
quantities which analysis of geological and engineering data demonstrate with reasonable
certainty to be recoverable in future years from known reservoirs under existing
economic and operating conditions.
Reservoirs are considered proved if economic producibility is supported by actual production
or conclusive formation test (drill stem or wire line), or if economic producibility is
supported by core analyses and/or electric or other log interpretations.
The area of a gas reservoir considered proved includes: (1) that portion delineated by
drilling and defined by gas -- oil and/or gas -- water contacts, if any; and (2) 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 is considered to be the lower proved limit of the reservoir.
Volumes of natural gas placed in underground storage are not to be considered proved
reserves.
For natural gas, wet after lease seperation, an appropriate reduction in the reservoir gas
volume has been made to cover the removal of the liquefiable portions of the gas in lease and/or
field separation facilities and the exclusion of nonhydrocarbon gases where they occur in
sufficient quantity to reder the gas unmarketable.
For dry natural gas, an appropriate reduction in the gas volume has been made to cover the
removal of the liquefiable portions of the gas in lease and/or field separation facilities,
and in natural gas processing plants, and the exclusion of nonhydrocarbon gases where they
occur in sufficient quantity to render the gas unmarketable.
It is not necessary that production, gathering, or transportation facilities be installed or
operative for a reservoir to be considered proved. It is to be assumed that compression
will be initiated if and when economically justified.
|
| Proved Reserves of Lease Condensate |
Proved reserves of lease condensate as of December 31 of the
report year are the volumes of lease condensate
expected to be recovered in future years in
conjunction with the production of proved reserves
of natural gas as of December 31 of the report year,
based on the recovery efficiency of lease and/or field
separation facilities installed as of December 31 of
the report year.
|
| Revisions |
Changes to prior year-end proved reserves estimates, either positive or negative,
resulting from new information other than an increase in proved acreage (extension).
Revisions include increases of proved reserves associated with the installation of
improved recovery techniques or equipment. They also include correction of prior
report year arithmetical or clerical errors and adjustments to prior year-end
production volumes to the extent that these alter reported prior year reserves
estimates.
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| Sales |
The volume of proved reserves deducted from an operator's total reserves when
selling an existing field or property, during the calendar year.
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Definitions