Abstract: Field Size Distributions for California Basins

David C. Bartel

Distribution curves for oil and gas field sizes can aid in assessing the future exploration potential of a basin. Field size distribution curves are presented for the San Joaquin, Sacramento, Ventura-Santa Barbara Channel, and Santa Maria basins. The data used here are largely from the published summaries of the California Division of Oil and Gas. It is not only important to look at the total distribution curve, but also the changes in the field size distribution curve through history. Since the basins used by example here are relatively well explored over the past approximately 100 yr, future fields will most likely be smaller than most fields that have already been found in the basin. This can be altered if significant changes in technology or opportunity occur. The field size distr bution can also be carried out at the individual reservoir pool or play level. Pool reserve size, and other parameters of the pool (e.g., net pay thickness), also seem to have a regular distribution that approximates a log-normal distribution. In the absence of other nearby geologic data for a play or prospect, such data could be used to estimate the parameters of a prospect. Summaries of existing data from the Upper Miocene Stevens reservoirs of the San Joaquin Valley will be shown. The data can be further subdivided into eastside and westside sourced Stevens reservoirs. Distribution curves for other prospective horizons could also be drawn from the available data.

AAPG Search and Discovery Article #90981©1994 AAPG Pacific Section Meeting, Ventura, California, April 27-29, 1994