69
Origin and Occurrence
constitute a resource. In these definitions, the quantities estimated to be initially-in-place are
(1) total petroleum-initially-in-place, (2) discovered petroleum-initially-in-place, and (3) undiscovered petroleum-initially-in-place. The recoverable portions of petroleum are defined separately as (1) reserves, (2) contingent resources, and (3) prospective resources. In any case and
whatever the definition, reserves are a subset of resources and are those quantities of petroleum
that are discovered (i.e., in known accumulations), recoverable, commercial, and remaining.
The total petroleum-initially-in-place is that quantity of petroleum that is estimated to exist
originally in naturally occurring accumulations. The total petroleum-initially-in-place is, therefore, that quantity of petroleum that is estimated, on a given date, to be contained in known accumulations, plus those quantities already produced therefrom, plus those estimated quantities in
accumulations yet to be discovered. The total petroleum-initially-in-place may be subdivided into
discovered petroleum-initially-in-place and undiscovered petroleum-initially-in-place, with discovered petroleum-initially-in-place being limited to known accumulations.
It is recognized that the quantity of petroleum-initially-in-place may constitute potentially
recoverable resources since the estimation of the proportion that may be recoverable can be subject
to significant uncertainty and will change with variations in commercial circumstances, technological developments, and data availability. A portion of those quantities classified as unrecoverable
may become recoverable resources in the future as commercial circumstances change, technological developments occur, or additional data are acquired.
Discovered petroleum-initially-in-place is that quantity of petroleum that is estimated, on a given
date, to be contained in known accumulations, plus those quantities already produced therefrom.
Discovered petroleum-initially-in-place may be subdivided into commercial and sub-commercial
categories, with the estimated potentially recoverable portion being classified as reserves and contingent resources respectively (as defined in the following).
Reserves are those quantities of petroleum that are anticipated to be commercially recovered
from known accumulations from a given date forward.
Estimated recoverable quantities from known accumulations that do not fulfill the requirement
of commerciality should be classified as contingent resources (as defined in the following). The
definition of commerciality for an accumulation will vary according to local conditions and circumstances and is left to the discretion of the country or company concerned. However, reserves must
still be categorized according to specific criteria and, therefore, proved reserves will be limited to
those quantities that are commercial under current economic conditions, while probable and possible reserves may be based on future economic conditions. In general, quantities should not be classified as reserves unless there is an expectation that the accumulation will be developed and placed
on production within a reasonable timeframe.
In certain circumstances, reserves may be assigned even though development may not occur for
some time. An example of this would be where fields are dedicated to a long-term supply contract
and will only be developed as and when they are required to satisfy that contract.
Contingent resources are those quantities of petroleum that are estimated, on a given date, to
be potentially recoverable from known accumulations, but which are not currently considered
as commercially recoverable. Some ambiguity may exist between the definitions of contingent
resources and unproved reserves. This is a reflection of variations in current industry practice
but if the degree of commitment is not such that the accumulation is expected to be developed
and placed on production within a reasonable timeframe, the estimated recoverable volumes for
the accumulation be classified as contingent resources. Contingent resources may include, for
example, accumulations for which there is currently no viable market, or where commercial recovery is dependent on the development of new technology, or where evaluation of the accumulation
is still at an early stage.
Undiscovered petroleum-initially-in-place is that quantity of petroleum that is estimated, on a
given date, to be contained in accumulations yet to be discovered. The estimated potentially recoverable portion of undiscovered petroleum-initially-in-place is classified as prospective resources,
Origin and Occurrence
constitute a resource. In these definitions, the quantities estimated to be initially-in-place are
(1) total petroleum-initially-in-place, (2) discovered petroleum-initially-in-place, and (3) undiscovered petroleum-initially-in-place. The recoverable portions of petroleum are defined separately as (1) reserves, (2) contingent resources, and (3) prospective resources. In any case and
whatever the definition, reserves are a subset of resources and are those quantities of petroleum
that are discovered (i.e., in known accumulations), recoverable, commercial, and remaining.
The total petroleum-initially-in-place is that quantity of petroleum that is estimated to exist
originally in naturally occurring accumulations. The total petroleum-initially-in-place is, therefore, that quantity of petroleum that is estimated, on a given date, to be contained in known accumulations, plus those quantities already produced therefrom, plus those estimated quantities in
accumulations yet to be discovered. The total petroleum-initially-in-place may be subdivided into
discovered petroleum-initially-in-place and undiscovered petroleum-initially-in-place, with discovered petroleum-initially-in-place being limited to known accumulations.
It is recognized that the quantity of petroleum-initially-in-place may constitute potentially
recoverable resources since the estimation of the proportion that may be recoverable can be subject
to significant uncertainty and will change with variations in commercial circumstances, technological developments, and data availability. A portion of those quantities classified as unrecoverable
may become recoverable resources in the future as commercial circumstances change, technological developments occur, or additional data are acquired.
Discovered petroleum-initially-in-place is that quantity of petroleum that is estimated, on a given
date, to be contained in known accumulations, plus those quantities already produced therefrom.
Discovered petroleum-initially-in-place may be subdivided into commercial and sub-commercial
categories, with the estimated potentially recoverable portion being classified as reserves and contingent resources respectively (as defined in the following).
Reserves are those quantities of petroleum that are anticipated to be commercially recovered
from known accumulations from a given date forward.
Estimated recoverable quantities from known accumulations that do not fulfill the requirement
of commerciality should be classified as contingent resources (as defined in the following). The
definition of commerciality for an accumulation will vary according to local conditions and circumstances and is left to the discretion of the country or company concerned. However, reserves must
still be categorized according to specific criteria and, therefore, proved reserves will be limited to
those quantities that are commercial under current economic conditions, while probable and possible reserves may be based on future economic conditions. In general, quantities should not be classified as reserves unless there is an expectation that the accumulation will be developed and placed
on production within a reasonable timeframe.
In certain circumstances, reserves may be assigned even though development may not occur for
some time. An example of this would be where fields are dedicated to a long-term supply contract
and will only be developed as and when they are required to satisfy that contract.
Contingent resources are those quantities of petroleum that are estimated, on a given date, to
be potentially recoverable from known accumulations, but which are not currently considered
as commercially recoverable. Some ambiguity may exist between the definitions of contingent
resources and unproved reserves. This is a reflection of variations in current industry practice
but if the degree of commitment is not such that the accumulation is expected to be developed
and placed on production within a reasonable timeframe, the estimated recoverable volumes for
the accumulation be classified as contingent resources. Contingent resources may include, for
example, accumulations for which there is currently no viable market, or where commercial recovery is dependent on the development of new technology, or where evaluation of the accumulation
is still at an early stage.
Undiscovered petroleum-initially-in-place is that quantity of petroleum that is estimated, on a
given date, to be contained in accumulations yet to be discovered. The estimated potentially recoverable portion of undiscovered petroleum-initially-in-place is classified as prospective resources,