Finite difference seismic forward modeling method for fluid-solid coupled media with irregular seabed interface

Abstract

The seismic wave fnite-difference numerical simulation of fluid-solid coupled media in a marine environment has many challenges, such as the accuracy of the forward modeling, ripple-shaped scattering at an irregular seabed and inaccurate travel-time. In this paper, a seismic forward-modeling method for fluid-solid coupled media (FSCM) with a transition layer is proposed. The second-order acoustic wave pressure equation and the second-order elastic wave displacement equation in heterogeneous media are used in the fluid and solid media, respectively. To improve the accuracy and stability of seismic wave propagation simulation in FSCM, the frst-order displacement-stress elastic wave equation is used as the transition layer to convert the pressure and displacement at the fluid-solid coupled interface, then a method for connecting the transition layer, the upper media and the lower media is presented. To overcome the ripple-shaped scattering in the irregular interface of the seabed, we resample the model to capture the seabed interface accurately, and use the Kaiser windowed sinc function flter to interpolate the resampled model to match the original mesh grid. This produces accurate reffected travel-time information while suppressing the ripple-shaped scattering. Finally, various models were tested to confrm the stability of the proposed method and the solution to the scattered-waves artifact problem.