Abstract
A simple effective-medium theory is presented, which is shown to reproduce sedimentary rocks’ striking microstructural feature of bicontinuity for the fluid and solid phases at any finite porosity. The effective medium involves three components—fluid, solid, and cement material—whose material properties are related to those of the composite through a differential effective-medium scheme. The theory provides a unified explanation for the observed correlations in both the electrical and elastic characteristics of sedimentary rocks.