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Line 60: − − [[File:Rose__uncertainties-impacting-reserves-revenue-and-costs__Table_1.png|thumb|{{table_number|1}}Biases affecting judgments under uncertainty]]
Uncertainties impacting reserves, revenue, and costs (view source)
Revision as of 17:29, 10 January 2014
, 17:29, 10 January 2014→Combining distributions
Note that multiplying the three ''P''<sub>90%</sub> values for area, net pay, and hydrocarbon recovery does not yield a ''P''<sub>90%</sub> value for reserves; in fact, it gives a product corresponding to 98.7%! Similarly, multiplying the three ''P''<sub>10%</sub> values gives a reserves product that corresponds to ''P''<sub>1.3%</sub>, not ''P''<sub>10%</sub>.
Note that multiplying the three ''P''<sub>90%</sub> values for area, net pay, and hydrocarbon recovery does not yield a ''P''<sub>90%</sub> value for reserves; in fact, it gives a product corresponding to 98.7%! Similarly, multiplying the three ''P''<sub>10%</sub> values gives a reserves product that corresponds to ''P''<sub>1.3%</sub>, not ''P''<sub>10%</sub>.
However, we can put this to work. First, plot the ''P''<sub>98.7%</sub> reserves product at ''P''<sub>98.7%</sub> on the log probability paper and the ''P''<sub>1.3%</sub> reserves product at ''P''<sub>1.3%</sub>. Draw a line connecting them. The median value should lie on or near the line at ''P''<sub>50%</sub>. Now, derive the values associated with ''P''<sub>90%</sub> and ''P''<sub>10%</sub> from the new reserves line and use them to solve for mean reserves using Swanson's Rule. Table 2 illustrates the calculations, and Figure 2 shows the graphical procedure. (As a reality check, you can also determine the mean values for area, net pay, and hydrogen recovery using Swanson's Rule, and then multiply them to yield a mean reserves figure that should approximate the previously calculated mean.)
However, we can put this to work. First, plot the ''P''<sub>98.7%</sub> reserves product at ''P''<sub>98.7%</sub> on the log probability paper and the ''P''<sub>1.3%</sub> reserves product at ''P''<sub>1.3%</sub>. Draw a line connecting them. The median value should lie on or near the line at ''P''<sub>50%</sub>. Now, derive the values associated with ''P''<sub>90%</sub> and ''P''<sub>10%</sub> from the new reserves line and use them to solve for mean reserves using Swanson's Rule. Table 2 illustrates the calculations, and Figure 2 shows the graphical procedure. (As a reality check, you can also determine the mean values for area, net pay, and hydrogen recovery using Swanson's Rule, and then multiply them to yield a mean reserves figure that should approximate the previously calculated mean.)