Estimation of Petrophysics from Thin Sections--Petrographic Image Analysis

Robert Ehrlich, John P. Horkowitz

Petrographic image analysis (PIA) consists of a series of programs that analyze digitized images of porosity from thin sections. A major product is an objective classification of porosity that is physically relevant and can be related to both depositional fabric and diagenesis. The relative proportions of such porosity types are strongly related to wireline log character and core test data. Relationships between resistivity logs and PIA pore types can be used to determine the relative wetting character of the reservoir. The relationships between PIA data, core tests, and well logs can identify lithofacies or "porosity facies" between which changes in parameters are needed to predict water saturation and oil saturation accurately from logs. Each pore type is usually associ ted with limited throat sizes and so can be related directly to mercury capillary porosimetry. In many cases, permeability and capillary pressure curves can be derived from thin-section data. Preliminary results indicate that this technique can be applied successfully to well cuttings.

AAPG Search and Discovery Article #91037©1987 AAPG Southwest Section, Dallas, Texas, March 22-24, 1987.