An 8,000-square-mile area of the Anadarko basin shelf in Oklahoma and Kansas was studied in 1956 to provide a forecast that hydrocarbons would be found in 50-80 per cent of a series of drilling ventures. Since 1956, more than 1,000 square miles have been proved productive and have been developed with a success ratio in excess of the predicted 50-80 per cent.

Conventional geological and reservoir engineering methods were used, augmented by probability/statistical theory which quantified and codified an exploration strategy to guide in the acquisition of leases. The deterministic versus the probabilistic approach to finding productive hydrocarbons is the problem. Because geology/land/engineering/economics are interrelated and inexact sciences in the oil business, more reliance must be placed on probability and statistics. There is no sharp demarcation between the beginning of one discipline and the beginning of another. The ideas on probability theory that commonly fall into disuse or misuse can be powerful mathematical tools in the search for hydrocarbons.

Geological maps, sections, and intervals are based on the original work. Rock and hydrocarbon distributions are then examined as a practical problem in statistical geometry by information theory, Bayesian methods, and the Laplace law of succession, much as a meteorologist can study cloud and weather patterns.

Regarding engineering, the pressure decline versus cumulative production of the predominantly gas reservoirs can be correlated statistically with the entropy of the shelf by random well sampling, or from wells selected by rigid, fixed patterns.

The economics and conversion to dollars can be figured through time by the amount of gas produced and the price paid by the pipeline companies. Leasehold and drilling costs are further related to the original forecast.

The mathematics serve well to predict the present status of this gigantic gas province from a small amount of data available in 1956. The continuing and expansive development of the reserves is testimony to the integrity of the approach through operations research methods.

End_of_Article - Last_Page 462------------