Seismic wavefield propagation in 2D anisotropic media: Ray theory versus wave-equation simulation

摘要

Despite the ray theory that is based on the high frequency assumption of the elastic wave-equation, the ray theory and the wave-equation simulation methods should be mutually proof of each other and hence jointly developed, but in fact parallel independent progressively. For this reason, in this paper we try an alternative way to mutually verify and test the computational accuracy and the solution correctness of both the ray theory (themultistage irregular shortest-pathmethod) and the wave-equation simulationmethod (both the staggered finite differencemethod and the pseudo-spectral method) in anisotropic VTI and TTI media. Through the analysis and comparison of wavefield snapshot, common source gather profile and synthetic seismogram, it is able not only to verify the accuracy and correctness of each of the methods at least for kinematic features, but also to thoroughly understand the kinematic and dynamic features of the wave propagation in anisotropic media. The results show that both the staggered finite differencemethod and the pseudo-spectralmethod are able to yield the same results even for complex anisotropic media (such as a fault model); the multistage irregular shortest-path method is capable of predicting similar kinematic features as the wave-equation simulation method does, which can be used to mutually test each other for methodology accuracy and solution correctness. In addition, with the aid of the ray tracing results, it is easy to identify themulti-phases (or multiples) in the wavefield snapshot, common source point gather seismic section and synthetic seismogrampredicted by thewave-equation simulation method, which is a key issue for later seismic application.