Three-dimensional transient electromagnetic virtual wave field propagation characteristics of electrical sources
摘要
Using the wave field transformation formula, a transient electromagnetic field satisfying the diffusion equation can be converted into a pseudo-seismic wave field satisfying the wave equation. The virtual wave field is not a physically existing field but wave field information obtained through mathematical integral transformation. To gain a more intuitive understanding of the virtual wave field, it is necessary to further describe and characterize the propagation characteristics and patterns of the virtual wave field corresponding to the transient electromagnetic field. This paper simulates the multi-component propagation characteristics of the virtual wave field for transient electromagnetic fields from electrical sources based on three-dimensional finite difference principles, employing complex frequency-shift absorption boundary conditions. Numerical simulation results reveal that the Ex, Ey, and Ez components of the transient electromagnetic virtual wave field exhibit relatively stable distributions. Compared to other components, the By component carries significantly less energy, while the Bx and Bz components propagate along the X and Z directions, respectively, with wavefield characteristics. The Bx and Bz components of the virtual wavefield exhibit good responsiveness to anomalous body models. Research findings indicate that virtual wavefields can be employed to detect and locate high-conductivity interfaces of subsurface targets.