ABSTRACT

A number of computer programs are in use in the oil industry to help provide rapid, reliable, and consistent paleoecological interpretations of paleontologic and lithologic data from wells drilled in the silico-clastic regime. Some of the more significant programs are described, and their value to the exploration program is demonstrated.

The basic input is the coded description of the fossil and lithologic constituents of washed well samples described by the paleontologists. The output is a basic, detailed paleontologic well log, plus several additional products, including paleoecologic logs and displays.

The basic paleontologic log consists of a sample-by-sample, coded, quantitative listing of fossil identifications and lithologic content of the entire well plotted to a vertical scale, usually 1 inch equals 100 feet.

Two types of paleoecologic products are particularly useful; namely (1) paleobathymetric well logs, and (2) occurrence charts on which fossils found in a well are arranged in sequence and groups according to their paleoecologic significance.

The ultimate objective is to utilize all the interpreted paleontologic data in the most effective manner for the maximum contribution to the exploration program. To this end, the logs are synthesized to produce paleobathymetric maps, cross sections, and other displays, which support the exploration effort in numerous ways; such as (1) reconstructing geologic history, (2) recognizing eustatic sea-level changes and evaluating their influence on reservoir sand distribution patterns, (3) enhancing well correlations, and (4) defining depositional trends which are favorable for hydrocarbon accumulation. A number of examples of these applications are presented.