3D P- and S-wave separation and elastic reverse time migration

Reverse time migration (RTM) can handle diving-wave, without dip and extreme lateral velocity limitation. Elastic reverse time migration inherits the advantage of traditional RTM, and uses P- and S-wave to get more subsurface information. However, if we just employ cross-correlation imaging condition of the corresponding components of source and receiver wavefields, the cross-talk between P- and S-wave will be generated. So, P- and S-wave separation is a vital step for elastic RTM. Most elastic RTM use divergence and curl operators to decompose P- and S-wave. Those separated wavefileds have different physical meaning with the input wavefileds. In addition, the divergence and curl operator will change the amplitude and phase information. In this paper, we present a 3D elastic wavefields separation method. This method separates P- and S-wave in elastic propagating equation, based on stress-particle-velocity, staggered-grid finite difference. We use this method to separate forward source wavefields and backward receiver wavefields into P- and S-wave components, then we do cross-correlation imaging condition with the corresponding wavefields to get PP and PS migration results. We use a 3D salt model to illustrate the validity of our method.