116 PETROLEUM TECHNOLOGY, ECONOMICS, AND POLITICS
to those reserves that are estimated using an improved understanding of reservoir frameworks. The term also usually includes those
reserves that can be recovered by further development of recovery technologies. Oil companies and government agencies use
unproved reserves internally for future planning purposes.
More recently, the Society for Petroleum Engineers has developed
a resource classification system (Figure 1.1) that moves away from
systems in which all quantities of petroleum that are estimated to be
initially-in-place are used. Some users consider only the estimated
recoverable portion to constitute a resource. In these definitions, the
quantities estimated to be initially in place are (1) total petroleuminitially-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, reserves
are a subset of resources and are those quantities 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 to be contained in known
accumulations, plus those quantities already produced therefrom
and 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 because
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 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 below.
to those reserves that are estimated using an improved understanding of reservoir frameworks. The term also usually includes those
reserves that can be recovered by further development of recovery technologies. Oil companies and government agencies use
unproved reserves internally for future planning purposes.
More recently, the Society for Petroleum Engineers has developed
a resource classification system (Figure 1.1) that moves away from
systems in which all quantities of petroleum that are estimated to be
initially-in-place are used. Some users consider only the estimated
recoverable portion to constitute a resource. In these definitions, the
quantities estimated to be initially in place are (1) total petroleuminitially-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, reserves
are a subset of resources and are those quantities 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 to be contained in known
accumulations, plus those quantities already produced therefrom
and 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 because
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 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 below.