Numerical Simulation of Seismoelectrograms

Abstract

The conversion of energy between seismic and electromagnetic wave fields involves relative movement of ions at the rock-fluid contact surfaces in the pore space, described by Biot’s equations of motion in poroviscoelastic media coupled with Maxwell’s equations. The numerical simulation of seismoelectrograms allows to analyze full-waveform coupled seismoelectromagnetic wave propagation in fluid-saturated porous media. It is possible to observe two different responses: the coseismic response with the same waveform as a seismic wave and the interface response that occurs when a seismic wave encounters a contrast in electrical or mechanical material properties. The proposed algorithm calculates the electromagnetic field from seismic displacements, particularly fluid displacements, using the finite element method employing a parallelizable non-overlapping domain decomposition technique, which is required due to the high computational cost of the problem. The seismoelectric method allows the possibility of detecting very thin impermeable layers, permeable fractures and interfaces between different formations due to changes in permeability or saturant fluids. The 2D implementation of the procedure illustrates identification of subsurface heterogeneities when applied to different targets and source-receiver configurations.