ABSTRACT: REESA--An Expert System for Geochemical Logging of Wells

PETERS, KENNETH E., Chevron Overseas Petroleum Inc., San Ramon, CA, and DAVID A. NELSON, Chevron Research and Technology Company, Richmond, CA

The Rock-Evaluation Expert System Advisor (REESA) is a user-friendly, PC-based computer program designed to provide rapid and reliable interpretation of large quantities of pyrolysis, total organic carbon (TOC), and vitrinite reflectance (Ro) data from drill cuttings. The program consistently improves data quality, shows potential petroleum source rock intervals, predicts the top and bottom of the oil generative window, and identifies zones containing migrated oil that may be suitable for drill-stem tests.

When supplied with raw data, the REESA software (1) "screens" anomalous input using a set of heuristic rules, (2) interprets the screened data using another set of rules, and (3) graphically displays the results in various formats readily used by the geologist.

REESA can be used with a mouse, which allows fully interactive graphics, blowups of detail on geochemical logs, and rapid acquisition of detailed information on individual samples from XY plots. Extensive well information, formation names/ages, and lithology symbols can be included on the geochemical logs. Default values for each rule can be manipulated by the user to rapidly test and compare the effects of various scenarios on results.

REESA has been successfully tested on hundreds of exploration wells. Geochemical conclusions from REESA are comparable to those reached by an expert, but require only a fraction of the interpretive time. Screening, interpretation, and preparation of print-quality geochemical logs and other plots can be completed within 10 minutes for a 20,000 ft well analyzed at 50 ft intervals for TOC and pyrolysis and at 250 ft intervals for Ro.

AAPG Search and Discovery Article #91012©1992 AAPG Annual Meeting, Calgary, Alberta, Canada, June 22-25, 1992 (2009)