Time-domain finite element method based on arbitrary quadrilateral meshes for two-dimensional SHTE mode seismoelectric and electroseismic waves modelling

A time-domain finite-element method based on an arbitrary quadrilateral mesh is proposed to simulate two dimensional seismoelectric and electroseismic waves in SHTE mode. By decoupling the electrokinetic coupling equation, we can solve seismic waves and electromagnetic waves independently. For the simulation of seismic wavefield, we utilize a more compact second-order unsplit perfectly matched layer that is easier to implement in finite-element methods. Moreover, to avoid errors caused by the quasi-static approximation, we directly solve the full-wave electromagnetic equations when simulating the electromagnetic wavefield. Our computational domain is discretized using arbitrary quadrilateral meshes, which offers possibilities in handling undulating terrain and complex anomalies in the underground. To ensure computational accuracy, we utilized biquadratic interpolation as our finite-element basis functions, which provides higher precision compared to bilinear interpolation. We validate our time-domain finite-element method by comparing its results with analytical solutions for a layered model. We also apply our algorithm to the modelling of an underground aquifer and a complex anomalous hydrocarbon reservoir under undulating terrain.