A high-efficiency topography anisotropic wave separation elastic reverse time migration method to image multi-component reflection seismic data in 2D VTI media

Shale gas reservoirs predominantly occurring in vertical transversely isotropic (VTI) media. For accurate seismic imaging in such environments, it is crucial to account for anisotropy effects, especially when imaging the multi-component field data acquired in areas with complex rugged topographies. To address these challenges presented by topography anisotropic wave separation elastic reverse time migration (TAWSERTM), we propose a novel TAWSERTM method, integrating two key technical advancements. We first develop a novel approach for wave mode separation in VTI media through anisotropic pseudo-decoupled wavefield equations. By theoretically decomposing elastic stiffness parameters into distinct P- and S-wave components, the anisotropic pseudo-decoupled wave equations for VTI media are established. The vector source- and receiver- anisotropic P- and S-waves for anisotropic wave separation elastic reverse time migration (AWSERTM) can be efficiently obtained by numerically solving the proposed anisotropic pseudo-decoupled wave equations through the finite difference (FD) method. We then present a robust surface-adaptive modeling scheme employing the traditional FD operator to eliminate the influence of complex irregular surface topography on topography ERTM. Synthetic examples demonstrate the high-efficiency and stability of the proposed TAWSERTM, which can not only obtain anisotropic P- and S-waves with high-efficiency, correct the anisotropy effect, but also effectively remove the impact of surface topography on migration results.