Local Plane Wave Tomography

We propose a local plane wave tomography where we use the output of a wave equation migration in a consistent manner as input to the tomography. The tomography is based on an efficient layer-stripping inversion of residual moveout of offset slowness gathers after double-square-root migration. The method does not require closeness of the initial model to the true model and it does not involve ray tracing through complex overburden. The results of testing on 2D synthetic FD data from the SEG-EAGE salt model are very promising. In the current work we use split-step-Fourier migration, but it is straightforward to extend the suggested approach to any other migration which provides information on incident and reflected angles at the image point. The considered tomography itself is very fast, but the whole layer-stripping process can be quite time consuming. The method requires at least one new migration for each layer included in the velocity model. Therefore, optimally, it should be used for target oriented velocity inversion in combination with faster approaches for simple overburden. Also, fast and reliable auto-picking of residual moveout is of crucial importance.