Organized Petrophysical Field Study

William R. Berry

Throughout the oil and gas industry, increasing emphasis is being placed on accurate reservoir description through the medium of petrophysical field studies. A petrophysical field study can be defined as "an assessment of the lithologic, volumetric, and fluid properties of a reservoir." A petrophysical field study integrates geological, engineering, and petrophysical data to obtain a meaningful and accurate appraisal of reservoir properties. The increasing availability of log and core data in existing or developing fields provides a data base from which quantification of reservoir properties can be predicted. These predictions are of value in the ongoing development of discovered fields, the evaluation of enhanced oil recovery simulations, the development of exploration s rategies, and other economically significant pursuits. The accuracy of such studies can only be assured when adequate geologic input has been provided. The petrophysical evaluation team must create mathematical models in a computer environment that satisfactorily relate raw sensor measurements, human observations, and laboratory measurements. The mathematical model must be calibrated with geologic knowledge of the reservoir. Of primary concern to the evaluation team are parameters influencing geologic phenomena. These include grain size, pore geometry, clay type, cement in the matrix pore system, fracture mechanisms, cement in the fracture system, formation water condition, facies types, facies changes, depositional environment, and zone correlations.

AAPG Search and Discovery Article #91030©1988 AAPG Annual Convention, Houston, Texas, 20-23 March 1988.