Elastic reverse time migration method in vertical transversely isotropic media including surface topography

Compared with acoustic seismic data, multi-wave and multi-component seismic data can offer some special media properties. Elastic reverse time migration is a high-precision migration method to image multi-wave and multi-component seismic data. Anisotropy widely exists in the earth, and it is important to take anisotropy into account and correct the anisotropy effect for obtaining high-quality image results during migration. However, accurate elastic reverse time migration in anisotropic media is still a challenging task, particularly for areas with irregular surface topography. To resolve these issues, a new elastic reverse time migration method is developed to correct the anisotropy effect in vertical transversely isotropic media with surface topography. We first use the modified pseudo-acoustic wave equations of vertical transversely isotropic media to assist the elastic wavefield separation in vertical transversely isotropic media for suppressing the crosstalk artefacts between different wave modes and further generating high-quality images. We then use a topography-related filter to remove the influence of surface topography on the migration results of elastic reverse time migration. The advantage of the proposed topography-related filter is that we do not need to make any changes to the conventional finite-difference method based on regular grids but can calculate the wavefield in the areas with irregular surface topography efficiently. The synthetic examples with different surface topographies models demonstrate that our proposed elastic reverse time migration method can correct the anisotropy effect effectively, remove the influence of surface topography on elastic reverse time migration results, and generate high-quality images.