A satisfactory solution to the problem of estimating petroleum resources in frontier areas is not available and will not be available until substantial numbers of strategically located wells are drilled. In the meantime, we must keep trying to develop better predictive techniques, and this basically means finding ways to maximize the input of our increasing knowledge of the generation, migration, and accumulation of oil and gas.
Some sharpening of estimates of the ultimate productivity of basins and petroleum zones can be made by quantifying the concept that the richness of a basin in reserves per cubic mile is a function of the amount of, and interaction between, four equally important factors: reservoir (R), trap (70, source (5), and migration (M). If these four factors are defined in a dimensionally consistent way, the reserves per cubic mile for a basin (or a sedimentary packet of any size) can be estimated from the formula: Estimated reserves/cu mi = R × T × S × M, where estimated reserves per cubic mile are in thousands of barrels and R, T, S, and M are rated on a normalized 0-10 scale. The 10 rating was empirically determined from the maximum value observed in over 50 well-explored basins. In general, both the ease and accuracy of determining R, T, S, and M decrease from T to R to S to M. Thus, the basic reason for the current increased interest in source and migration studies is that they have the greatest potential for increasing the accuracy o f prediction.