Conclusions

This paper demonstrates that angle-domain common image gathers generated by wave-equation migration can be used for AVA analysis if proper care is taken to ensure that amplitudes are not distorted during processing. Angle gathers can be computed both in the image space (with output in true reflection angle) or in the data space (with output in offset ray-parameter). The image-space method is independent of the structural dip. The two most important factors that influence the accuracy of the amplitude response are the sampling of the offset axis and the incorrect treatment of amplitudes during migration. While the limited sampling cannot be corrected, the migration operator can be modified to incorporate the appropriate correction factors. We have analyzed the Jacobian compensation factors, and show that they can successfully be applied to real data. We have shown how to construct ``true amplitude'' wave-equation migration operators, as well as pseudo-unitary modeling and migration operators.

This research was partially funded by the ACTI project #4731U0015-3Q. Some of this work was prompted by discussions with John Etgen at BP.