The Thermal Diffusivity of Sedimentary Rocks: Empirical Validation of a Physically Based α − φ Relation

Understanding the thermal behavior of nonsteady state subsurface geosystems, when temperature changes over time, requires knowledge on the speed of heat propagation and, thus, of the rock's thermal diffusivity as essential thermo-physical parameter. Mixing models are commonly used to describe thermo-physical properties of polymineralic rocks. A thermal diffusivity-porosity relation is known from literature that incorporates common mixing models into the heat equation and properly works for unconsolidated, clastic clayey, and sandy marine sediments of high porosity (35%–80%). We have proofed the relation's applicability for consolidated, isotropic sedimentary rocks of low porosity (