Permeability prediction based on fractal pore-space geometry

Estimating permeability from grain-size distributions or from well logs is attractive but difficult. In this paper we present a new, generally applica ble, and relatively inexpensive approach which yields permeability informat ion on the scale of core samples and boreholes. The approach is theoretical ly based on a fractal model for the internal structure of a porous medium. It yields a general and petrophysically justified relation linking porosity to permeability, which may be calculated either from porosity or from the pore-radius distribution. This general relation can be tuned to the entire spectrum of sandstones, ranging from clean to shaly. The resulting expressi ons for the different rock types are calibrated to a comprehensive data set of petrophysical and petrographical rock properties measured on 640 sandst one core samples of the Rotliegend Series (Lower Permian) in northeastern G ermany. With few modifications: this new straightforward and petrophysicall y motivated approach can also be applied to metamorphic and igneous rocks. Permeability calculated with this procedure from industry porosity logs com pares very well with permeability measured on sedimentary and metamorphic r ock samples.