Modifications to the Kozeny–Carman model to enhance petrophysical relationships

Abstract

The most commonly used relationship that relates permeability, porosity, grain size and tortuosity is the Kozeny–Carman equation. When it is used to estimate the permeability behaviour versus porosity, the other two parameters (the grain size and tortuosity) are usually kept constant. In this study, we investigate the deficiency of the Kozeny–Carman assumption and the alternative derived equations for the Kozeny–Carman equation is presented, including equations where the grain size is replaced with the pore size with varying tortuosity. We also introduce relationships for the permeability of shaly sand reservoir that answer the approximately linear permeability decreases in the log-linear permeability–porosity relationships in datasets from different locations.