An investigation of permeability, porosity, and residual water saturation relationships

Abstract

A reasonably accurate relationship for estimating permeability of sandstones from in situ measurements of porosity and residual fluid saturation (the latter to be obtained from FFI, measured by nuclear magnetism log) would be instrumental in eliminating the expense of coring. To establish such a relationship several possibilities were tested, through laboratory measurements of permeability (K), porosity (φ), and residual water saturation (Swr) on 15 5 sandstone samples from three different oil fields in North America. The empirical equation (Equation presented) was found to be the best estimator of permeability. To simplify its use, this equation was plotted in the form of a chart from which the value of K can be obtained, by entering the respective values of φ and Swr. The application of this formula for estimating permeabilities in three different oil fields is illustrated through scatter diagrams that plot log K vs log (φ4.4./S2wr). The estimating of residual water saturation in sandstones, when porosity and permeability are known, was also investigated by testing several possible relationships. The best one was found to estimate Swr from a combination of measurements of φ and K, with a standard error of 13% pore volume.