A First-order qSV-wave Propagator in 2D VTI Media

The study on the propagation of elastic wavefield in heterogeneous anisotropic formation has always been essential to surface seismic exploration. In VTI media, qP- and qSV-mode waves are intrinsically coupled and will not propagate parallel or perpendicular to their polarization direction, respectively. Elastic reverse time migration and imaging algorithms should betterbe performed with separated qSV-mode waves,because qP-wave energy will contaminate the migration and imaging results. In this study, we propose a first-order pseudo-pure-mode qSV-wave propagator in 2D VTI media, which can be easily employed for the simulation of qSV-mode wave propagation with staggered-grid scheme. Since the simulated wavefields still contain residual qP-wave energy, simulated wavefields need to be further projected onto anisotropic references of local polarization direction by applying spatial domain deviation operators, which will remove residual qP-wave energy completely. In addition, the more efficient and more stable Hybrid-PML can be directly implemented in this first-order finite difference algorithm,which will showbetter performance in the simulation of VTI media with strong anisotropy. In this paper, several simulation examples are presented, which demonstrate that the new algorithm combined with Hybrid-PML can be efficiently employed for the simulation of qSV-mode wave propagating in 2D heterogeneous VTI media.