Paper Summary

Tilted Transverse Isotropic (TTI) Reverse Time Migration (RTM) is routinely used for depth velocity model building. To improve the efficiency of RTM we have developed an approach called layer-stripping RTM. For this method, we divide the model into two or three horizontal regions, then run RTM sequentially from top to bottom. The key ingredient for layer-stripping RTM is wavefield redatuming. For the top region, we run a regular RTM and save the wavefield at the bottom of the top region. The saved, redatumed wavefields become the input for the subsequent, deeper RTM run. This method can dramatically reduce computation cost and improve the efficiency of model updates, because we do not need to repeat the shallow wavefield extrapolation, and the grid size of the deeper migrations can be increased. Additionally, we present solutions to practical issues such as the 3D data explosion problem of redatumed wavefields.