Evaluating Conceptual Plays
115
chi-square tests that indicated three pairs of factors (closure and
source, closure and seal, and facies and source) were dependent factors,
whereas other pairs were independent. The data set was also subjected
to correlation analysis. For all dependent pairs of factors, signifi cant
correlation was established.
The East Coast Play
Table 5.4 displays the factors and their marginal probabilities for a conceptual play from the East Coast of Canada. The assessor interpreted
the geological factors as either play-level or prospect-level geological
factors. The fi rst column displays the names of the geological factors;
the second column shows the corresponding marginal probability. The
Table 5.3. Example of Data Set for Exploration Risk
Analysis
Closure
Reservoir facies
Migration
Source
1
0
1
1
0
1
1
1
1
1
0
1
1
1
1
1
0, absent; 1, present.
Table 5.4. Marginal Probabilities Used to Calculate Exploration Risk for the
East Coast Conceptual Play
Geological factor
Marginal
probability
Case
I
I I
Presence of closure
0.95
Prospect
Prospect
Presence of facies
0.90
Prospect
Prospect
Adequate timing
0.95
Play
Play
Adequate seal
0.80
Prospect
Prospect
Adequate source
0.75
Prospect
Play
Adequate preservation
0.80
Prospect
Play
Overall play-level geological factor
0.95
0.57
Overall prospect-level geological
factor
0.41
0.68
Exploration risk
0.39
0.39