8
Statistical Methods for Estimating Petroleum Resources
Statistical concepts such as the superpopulation concept can be applied
to geological models so that, for specifi c plays, an estimate of undiscovered pool sizes can be made.
Figure 2.1 illustrates various sedimentary environments (tidal fl at,
lagoon, beach, and patch reef) that can be used as geological models in
resource evaluation. Each of these models has its own distinguishing
characteristics of source, reservoir, trapping mechanism, burial and
thermal history of source beds, and migration pathway. In resource
evaluation, to ensure the integrity of statistical analysis, each of these
should be treated as a separate, natural population. Therefore, the
logical steps in describing a play are (1) identify a single sedimentation
model and (2) examine subsequent geological processes.
Geological processes such as faulting, erosion, folding, diagenesis,
biodegradation, thermal history of source rocks, and migration history might provide a basis for further subdivisions of the model.
In some cases, two or more populations might be considered mistakenly as a single population because of a lack of understanding of
the subsurface geology. If the resulting mixed population were to have
two or more modes in its distribution, this could have an impact on
resource evaluation results.
As an example, let us look at the Devonian Leduc reef trend from the
Western Canada Sedimentary Basin (Reinson et al., 1993), as displayed
Figure 2.1. Examples of geological models: tidal fl ats, beach sand, patch reefs,
and lagoon (after Wilson and Jordan, 1983). Each model may be defi ned as a basic
unit for assessment.
Statistical Methods for Estimating Petroleum Resources
Statistical concepts such as the superpopulation concept can be applied
to geological models so that, for specifi c plays, an estimate of undiscovered pool sizes can be made.
Figure 2.1 illustrates various sedimentary environments (tidal fl at,
lagoon, beach, and patch reef) that can be used as geological models in
resource evaluation. Each of these models has its own distinguishing
characteristics of source, reservoir, trapping mechanism, burial and
thermal history of source beds, and migration pathway. In resource
evaluation, to ensure the integrity of statistical analysis, each of these
should be treated as a separate, natural population. Therefore, the
logical steps in describing a play are (1) identify a single sedimentation
model and (2) examine subsequent geological processes.
Geological processes such as faulting, erosion, folding, diagenesis,
biodegradation, thermal history of source rocks, and migration history might provide a basis for further subdivisions of the model.
In some cases, two or more populations might be considered mistakenly as a single population because of a lack of understanding of
the subsurface geology. If the resulting mixed population were to have
two or more modes in its distribution, this could have an impact on
resource evaluation results.
As an example, let us look at the Devonian Leduc reef trend from the
Western Canada Sedimentary Basin (Reinson et al., 1993), as displayed
Figure 2.1. Examples of geological models: tidal fl ats, beach sand, patch reefs,
and lagoon (after Wilson and Jordan, 1983). Each model may be defi ned as a basic
unit for assessment.