Hybrid Acoustic-elastic Modeling Method Using Adaptive Grid Finite Difference Scheme in Marine Environment

Shear- and mode-converted waves provide rich information for further improving the image quality of complex geological structures and quantification of reservoir characterization. Multi-component seismic data acquisition has become more and more popular for surface seismic, Ocean Bottom Cable (OBC), and Vertical Seismic Profile (VSP) over the recent years. The staggered-grid finite-difference (FD) method with velocity-stress wave equation is often used for elastic wave simulation. Conventional elastic wave simulation uses fixed-grid discretization throughout the 3D volume. It requires a huge computing cost and encounters oversampling with high velocity. In order to make elastic modeling more cost effective in marine environment, we propose a new hybrid method to perform 3D elastic modeling. We implement the first-order acoustic wave equation used in water layer and the velocity-stress elastic wave equation with adaptive grid in solid sediment. The numerical result of the hybrid method matches very well with the conventional approach using fixed-grid implementation with full elastic wave equation. Test on the SEAM model also demonstrates that this method is capable for modeling surface seismic, OBC and VSP acquisition geometry with greatly improved efficiency and less used computing resource.