Digital Rock Physics - Effect of Fluid Viscosity on Effective Elastic Properties

This paper is concerned with numerical simulations of effective transport and effective mechanical properties of representative rock samples. We derive these properties directly from rock microstructure using 3D tomographic images. Permeability values were estimated through Lattice-Boltzmann (LB) flow simulations. The effective shear and P-wave moduli are derived by dynamic wave propagation simulations. We apply a displacement-stress rotated staggered finite-difference (FD) grid technique to solve the elastodynamic wave equation. An accurate approximation of a Newtonian fluid is implemented in this technique by using a generalized Maxwell body. The fluid viscosity is varied to consider different attenuation regimes. We give a practical description of how to use this approach and discuss our results with respect to different well-known mechanisms. Additionally, we show the simulated signature of a theoretically predicted slow S-wave.