Analysis of the Relations between Porosity and Permeability in Non-Consolidated Granular Media

Few natural rock properties have received more attention than porosity and permeability. The variation of these two properties is associated with some factors as: pore space geometry and distribution, textural parameters, pore throat size and capillary pressure. In this sense, the study of the pore throat radii distribution, through Pittman’s equations, is useful in reservoir characterization. The aim of this study was to establish empirical relations and their applications in the dynamic and static flow properties, through the characterization of simple granular materials. In order to accurately describe the microstructural parameters of these media 16 samples were studied, and three relations were proposed after analyzing the 2D distribution of the pore throat radii in monodisperse and spherical granular samples, with diameters ranging between 1.5mm and 7.5mm. The permeability was calculated using both, a falling-head permeameter for the volumetric media, and the Pittman’s equations for the 2D images of the samples. The porosity was estimated with an image processing algorithm. Using the regression analysis, it was found that pore throat radii of 70%, 80% and 85% yield the best correlation for permeability, porosity and pore throat size for monodisperse granular samples. This study indicates that higher pore throats than those proposed by Pittman are the best representatives for estimating permeability from 2D images of coarse grained granular media.

AAPG Search and Discovery Article #90142 © 2012 AAPG Annual Convention and Exhibition, April 22-25, 2012, Long Beach, California