Conclusions

The accurate transformation from subsurface offset-domain CIGs into angle-domain CIGs for the converted-mode case requires, the information along the midpoint axis, and the velocity ratio. Omitting this information leads to errors in the transformation that might result in incorrect velocity updates.

For the converted-mode case, the angle axis of the final image ($I({\bf m_{\xi}},\gamma)$), after the transformation, is neither the incidence nor the reflection angle, but the average of both. The full-aperture angle gathers can be transformed into two separate angle gathers, each one representing the incidence angle and the other representing the reflection angle. This transformation might yield useful information for the analysis of rock properties or velocity updates for the two different velocity models.

The next step will be to analyze how errors in either P or S velocity models are transformed in the PS-ADCIGs. This will result in both a formulation for the residual moveout of converted-mode data, and a methodology for vertical velocity updates of both P and S velocity models.