HR: 1340h
AN: S53B-1273    [Abstracts]
TI: Spectral-Element Simulations of Wave Propagation in Porous Media
AU: * Morency, C
EM: cmorency@gps.caltech.edu
AF: Caltech, 1200 E. California Blvd, Pasadena, CA 91125, United States
AU: Tromp, J
EM: jtromp@gps.caltech.edu
AF: Caltech, 1200 E. California Blvd, Pasadena, CA 91125, United States
AB: Biot theory has been extensively used in the petroleum industry, where seismic surveys are performed to determine the physical properties of reservoir rocks. The theory is also of broad general interest when a physical understanding of the coupling between solid and fluid phases is desired.
One fundamental result of Biot theory is the prediction of a second compressional wave, which attenuates rapidly, often referred to as "type II" or "Biot's slow compressional wave", in addition to the classical fast compressional and shear waves.
The mathematical formulation of wave propagation in porous media developed by Biot is based upon the principle of virtual work, ignoring processes at the microscopic level. Moreover, even if the Biot formulations are claimed to be valid for non-uniform porosity, gradients in porosity are not explicitly incorporated in the original theory. More recent studies focused on averaging techniques to derive the macroscopic porous medium equations from the microscale, and made an attempt to derive an expression for the change in porosity, but there is still room for clarification of such an expression, and to properly integrate the effects of gradients in porosity.
We aim to present a straightforward derivation of the main equations describing wave propagation in porous media, with a particular emphasis on the effects of gradients in porosity. We also present a two dimensional numerical implementation of these equations using a spectral-element method. Finally, we have performed different benchmarks to validate our method, involving acoustic-poroelastic waves interaction and wave propagation in heterogenous porous media.
DE: 7290 Computational seismology
SC: Seismology [S]
MN: 2007 Fall Meeting