Dynamic permeability and tortuosity in weakly consolidated granular media

Abstract

Micro-scale rock heterogeneity plays an important role in modifying the seismic response of porous media and must be considered in reservoir studies such as seismic monitoring of fluid flow or interpretation of Stoneley waves. This work focuses on the prediction of dynamic permeability and dynamic tortuosity of granular media at different frequencies from porosity and average grain size data, utilizing numerical simulations. The simulations are conducted through cubic consolidated and unconsolidated digital rock samples of three different rock types, by applying a macroscopic oscillatory pressure gradient to each porous medium and combining fluid flow with solid mechanics to solve the wave propagation problem. The JKD parameter called dynamically connected pore size (Λ) is then predicted for each rock type. We investigate how pore space geometry, cement content and morphology, and matrix heterogeneity can influence the dynamic and geometrical tortuosities.