New Statistical Model for Sizes of Undiscovered Oil and Gas Fields

Claudio Bettini, John W. Harbaugh

Before an oil or gas field is discovered in a petroliferous sedimentary basin, the overall present (albeit undiscovered) field population can be separated into two complementary subpopulations. One subpopulation consists of the fields that are larger than a given cutoff size and are therefore potentially discoverable and producible. The statistical distribution of this population can be represented by the log normal distribution. However, the other subpopulation is poorly known because it consists of the hydrocarbon accumulations that are either too small to be discovered or too small to be economic. The form of the overall population differs substantially from the lognormal distribution of discoverable fields. The Pareto distribution provides a better representation for he overall population, but it too has limitations. The statistical distribution that we propose can be termed the "log-Pareto" distribution, and can be defined with either two or three parameters.

AAPG Search and Discovery Article #91043©1986 AAPG Annual Convention, Atlanta, Georgia, June 15-18, 1986.