Chapter 7 Interrelationships Among Surface Area, Permeability, Porosity, Pore Size, and Residual Water Saturation

Publisher Summary This chapter discusses the fundamental relationships for the porous medium of carbonate rocks, both from a pore-size portrait scale and at a macroscopic descriptive scale. There is a reasonable correlation between the porosity and permeability of cores having irreducible (immobile) fluid saturation in the minute pores, crevices, and so on, which do not have a major effect on the flow of fluids through the rock. Several correlations are developed that relate specific surface area of hydrocarbon-bearing reservoir rocks to other petrophysical properties (such as porosity, permeability, and pore size) and residual water saturation. Permeability is one of the most important parameters describing a porous medium, its measurement normally requires a rock sample that is of a suitable size (e.g., 5 cm x 5 cm x 5 cm) and has a simple geometric shape (for example, a cylinder or a cube). Correlations between the permeability and other easier-to-measure quantities, therefore, are discussed extensively both experimentally and theoretically. Several theoretical relationships between tortuosity and porosity have been developed for simplified models, two of which are presented.