Wave propagation in cracked elastic media based on EMT using FEM

Understanding mechanism of wave propagation in elastic media with cracks is the key scientific issue in exploration and extraction of shale and other unconventional oil and gas resources. Based on the advantages of the numerical simulation, the excitation and propagation of elastic wave in the cracked media were simulated by Nastran, a commercial solver for finite element analysis. Then the dependence of dynamic characteristics of propagation in that kind of media was further analyzed based on the microstructure (crack density, aspect ratio). Some conclusions were obtained as follows. Finite element method (FEM) would be effectively used to study the issue. Hudson's effective medium theory (EMT) could not be applied into materials with Poisson's ratio of nearly 0.5. Increasing crack density and aspect ratio would reduce the primary wave (P wave) velocity, with decaying the displacement amplitude of the P wave in time-domain. Crack density of the medium exposes greater effect on the anisotropy than the aspect ratio. ©, 2015, Beijing University of Aeronautics and Astronautics (BUAA). All right reserved.