The objective of this work is to apply computer image analysis methods to measurements of pore and grain parameters in reservoir rocks and to use the measured values of these parameters to predict petrophysical properties such as porosity, permeability, and capillary pressure. By computer image analysis, rapid measurements of pore and grain diameters, areas, and perimeters can be performed, and from these measurements various other parameters, such as shape factor, form factor, and specific surface can be derived. A commercially available PC-based image analysis system previously adapted for computations of petrophysical properties has been improved. Based on pore and pore throat measurements, rapid and reliable predictions of porosity, permeability, grain size distribution, and capillary pressure can be made from thin sections fabricated from rock samples as small as drill cuttings. 9 refs., 11 figs., 3 tabs.