Conclusions and Future work

The accurate transformation from subsurface offset-domain CIGs into angle-domain CIGs for the converted-mode case requires both the information along the midpoint axis and the velocity ratio. Omitting this information yields to errors in the transformation that might transforms in wrong velocity updates. Two separate approaches to obtain the relation between the subsurface offset and the full-aperture angle corroborates the accuracy of our formulation.

For the converted-mode case, the angle axis of the final image ($I(z_\xi,m_\xi,\gamma)$), after the transformation, is neither the incidence nor 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 and reflection angle. This transformations might bring useful information for the analysis of rock properties or velocity updates for the two different velocity models.

The transformation from SODCIGs into ADCIGs with a Fourier domain approach is accurate only for constant velocity. The general transformation needs to be done in the image space. Radon Transforms may provide to be a solution for this situation. The method will use the information along both the midpoint and subsurface offset axes in order to map the image into the full-aperture angle axis.

The next step is 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.