Mesh-free based seismic modeling and reverse-time migration with surface topography

Abstract

When seismic data are acquired over an irregular topographic surface, honoring topographic variations poses challenges to existing modeling algorithms. To deal with the challenges, the mesh-free scheme is introduced to seismic modeling with surface topography because of its two advantages. First, the mesh-free scattered nodes avoid grid constraints and can conform irregular surfaces. Second, the scattered nodes' radii vary adaptively with the velocity, which could overcome the over-sampling problem and improve the computational efficiency. To implement numerical modeling based on mesh-free discretization, the radial-basis-function-generated finite-difference (FD) method is introduced to solve the differential equations. Moreover, to effectively suppress the spurious reflections from the artificial boundaries, we employ the hybrid absorbing boundary condition (ABC) method for the seismic modeling. To demonstrate the superiority of the modeling with the mesh-free based RBF-FD method, we analyze its dispersion and stability. Finally, we implement the reverse time migration (RTM) on the topographic Marmousi model to demonstrate that the mesh-free RBF-FD method-based RTM is a viable imaging method for seismic data recorded in areas with complex subsurface structures and irregular surfaces, while the adaptive scattered nodes' radii could greatly improve the migration computational efficiency.