In this chapter I describe how to combine Kirchhoff datuming with Kirchhoff migration to image complex structures with first-arrival traveltimes from a finite-difference solution to the eikonal equation. The novel concept presented in this chapter is that by breaking up a complex velocity model, it is possible to calculate traveltime tables for migration that are well behaved and that produce excellent images.

The hybrid layer-stripping migration algorithm produces accurate images of complex structures by downward continuing the data and imaging from a lower datum. The method alternates steps of datuming and imaging. Because traveltimes are computed for each step, the adverse effects of caustics, headwaves, and multiple arrivals do not develop. In principle, this method only requires the same number of traveltime calculations as a standard migration.

Using the Marmousi synthetic data set, I compare the result of the layer-stripping migration to images obtained with standard migration algorithms and also with Kirchhoff migration using traveltimes from maximum-amplitude paraxial ray tracing and a band-limited Green's function method.

- Kirchhoff imaging of complex structures
- First-arrival traveltimes in complex velocity models
- Layer-Stripping Kirchhoff migration
- Comparison to other migrations
- Imaging with an approximate velocity model
- Implications for velocity estimation and 3-D imaging
- Summary

2/12/2001