Permeability Estimation Based on Pore Radius and Its Distribution

Abstract

Hydraulic permeability may be expressed as a function of pore radius. A simple capillary model shows that permeability is proportional to the square of pore radius. This model may be extended by including pore size distribution, so statistical parameters of its pore radius distribution can be considered in permeability estimation. Another recent approach, the so-called effective medium approximation uses pore radius distribution as an input parameter for permeability calculation.
Permeability can be estimated with the help of the above approaches as far as the pore radius and its distribution are available. Pore radius distribution can be generated using digital image processing. By defining pore radius as the ratio of image pore area and its circumference, pore size distribution of rock image can then be created.
Estimation of permeability by means of the effective medium approximation gives better results than the simple capillary model as well as its extended formulae. Definition of pore radius has however significant influence on the results of estimation, since different definitions of pore radius produces different distributions.