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Statistical Methods for Estimating Petroleum Resources
What is the value that just exceeds the maximum that the model
4.
can reasonably be expected to have? This value will be set at
zero in the upper percentile of the probability distribution.
What is the largest possible value that the model can have?
5.
This will be set at the 99th or 98th upper percentile of the probability distribution.
What is the value that is exceeded by half the members of the
6.
population? This will be placed at the 50th percentile of the
distribution.
What is the minimum value? This will be set at the 1st
7.
percentile.
In determining the geological factors that dictate the fi nal
8.
accumulation of hydrocarbons, one might ask: What are the
most unpredictable risk factors in this model?
The number of prospects can be obtained from anomalies
9.
showing closure on a structural contour map of time isochrons
constructed from seismic data. However, some questions
Table 5.14. Format for Entry of Number of Prospects and Pools
Geological variable
Probability in upper percentile
0.99
0.5
0.0
No. of prospects
No. of pools
Table 5.13. Format for Entry of Geological Factors and Their Marginal
Probability
Geological factors
Marginal probability
Play-level prospect
Presence of closure
Presence of reservoir facies
Presence of porosity
Adequate seal
Adequate timing
Adequate source
Adequate maturation
Adequate preservation
Adequate recovery
Adequate play conditions
Adequate prospect conditions