Numerical simulations of time-domain seismic wave propagation for a point source in 2-D onshore and offshore geological models

This research demonstrates an innovative numerical technique to simulate seismic wave propagation of a practical point source in complex 2-D geological models, which encompass a free surface topography, an undulating seafloor, and acoustic, elastic isotropic, viscoacoustic and viscoelastic anisotropic rocks. This technique is particularly beneficial in scenarios where 3-D wave modeling is resource-intensive and may efficiently offer the 3-D wavefields from arbitrary 2-D geological models often encountered in practice. Based on the point-source viscoelastic wave equations in a 2-D heterogeneous tilted transversely isotropic (TTI) medium, representative of subsurface igneous and sedimentary rocks, we tailor the wave equations valid for different rocks and the boundary conditions of the free-surface topography and seafloor and adapt the conventional memory variable method and the newly developed Taylor-series recursive convolution method to solve such point-source comprehensive wave equations. To overcome the inherent computational intensity of the methods, we convert the complex domain into a real domain and implement a fully parallelized computing strategy to ensure that the runtime of the numerical simulation remains on par with that of common 2-D wave modeling. Our experimental validations confirm the accuracy of the Taylor-series recursive method to offer the 3-D wavefields in an arbitrary heterogeneous 2-D geological model having a free-surface topography or an undulating seafloor. Moreover, our applications of this technique to two benchmark practical 2-D geological models demonstrate its capability to replicate 3-D wavefields in arbitrary viscoelastic anisotropic media, and greatly help in interpreting offshore and onshore seismic data and generating an accurate image of the subsurface.