Numerical simulation of seismoelectric wavefields in 3D orthorhombic poroelastic medium

The anisotropy and other medium parameters have influences on the propagation of seismoelectric wavefields. With the aim of quantitatively analyzing the effects of medium parameters on seismoelectric wavefields, we firstly studied the seismoelectric coupling equations in 3D orthorhombic poroelastic medium, and then computed the seismoelectric responses by time domain finite-difference algorithm with an explosive source. In numerical simulation, we firstly simulated the seismic wavefields, and then used seismic wavefields as input to compute electric wavefields. We compared the numerical results with analytical results obtained from Pride equations to test the algorithm and find that the analytical solution is well approximated by numerical solution. We designed several anisotropic models and analyzed the influence of medium parameters on the seismoelectric wavefields. Numerical results show that the explosive source generates four types of seismic waves in anisotropic porous medium, which are two separable transverse waves and the fast and slow longitudinal waves. All seismic waves were accompanied by coseismic electric wavefields in homogeneous anisotropic porous medium. The tortuosity has an influence on the propagation of slow longitudinal waves. The wavefield snapshot of slow longitudinal wave has an oval shape when the tortuosity is anisotropic, while it has a circular shape when the tortuosity is isotropic.