Numerical Investigation of the Effective Skempton Coefficient in Porous Rock Containing Fluid-Filled Fracture Networks

Paper in proceeding, 2017

Modern interpretation of seismic surveys aims at going beyond structural characterization of reservoirs on the basis of the spatial distribution of velocity. In particular, hydraulic properties of fluid-filled reservoirs are of prime interest for hydrocarbon exploration or water-reservoir management. Such analyses require a physics-based understanding of the processes involved with the propagation of seismic waves in fractured rocks. The main objective of this work is the investigation of the hydro-mechanics of fluid-filled fracture networks and the related diffusion of fluid pressure in the conduits. We apply methods of computational homogenization to discuss an effective Skempton coefficient and analyze it for different setups in time as well as in frequency domain. In the first setup we investigate a modified version of Cryer's problem embedding a spherical sample in a mantle of constant thickness. The kernel and the mantle constitute porous media but with different material properties. The second setup aims to investigate the hydro-mechanical properties of stochastically generated fracture networks. In both setups we apply Biot's theory of linear consolidation. Evaluating the effective Skempton coefficient predicted by computational homogenization for those cases we can show limitations of previously performed laboratory measurements of the Skempton coefficient.