Abstract: A Comparison of Undiscovered Oil and Gas Resource Estimates, Los Padres National Forest in the Ventura Basin Province, California

Kenneth J. Bird, Desmond M. Bain, Thomas E. Hopps, Jeanine S. F. Friehauf, Zenon C. Valin

Two recent assessments of the undiscovered oil and gas resources of Los Padres National Forest lands in the Ventura Basin Province using different methodologies and personnel show remarkable coincidence of estimated resources. The 1989 U.S. Geological Survey assessment was part of a National appraisal. In it, a team of assessors used a play analysis/discovery process method in which subjective estimates of sizes and numbers of undiscovered accumulations were the primary input. In the Ventura Basin province, two separate plays were assessed and a percentage of resources from these plays was allocated to Federal lands. Virtually all Federal lands in the Ventura Basin Province are within the Los Padres National Forest. By this allocation, the undiscovered oil and gas resourc s of this part of the Los Padres National Forest are estimated to range from <10-140 MMBO (mean probability 60 MMBO, million barrels of oil) and 10-250 BCFG (mean probability 110 BCFG, billion cubic feet of gas).

In 1993, the U.S. Forest Service completed an oil and gas assessment of the entire 1.8 million-acre Los Padres National Forest as part of a Reasonably Foreseeable Oil and Gas Development Scenario. In those areas of the forest considered to have high potential for the occurrence of oil and gas deposits, a deposit simulation model was used. This method is based on a fundamental reservoir engineering formula incorporated in the USGS computer program FASPU (Fast Appraisal System for Petroleum-Universal). Of the twelve prospective areas analyzed, seven occur within the Ventura Basin province. By this method, the undiscovered oil and gas resources of this part of the Los Padres National Forest are estimated to range from 0-182 MMBO (mean probability 56 MMBO) and 9-233 BCFG (mean probability 103 BCFG). An additional 6 MMBO (mean probability) is allocated to forest lands with medium potential within this province but not to any specific prospects. The remarkable coincidence of estimated resources resulting from such different assessment methods and personnel is noteworthy and appears to provide an increased measure of confidence in the estimates.

AAPG Search and Discovery Article #90958©1995 AAPG Pacific Section Meeting, San Francisco, California