Summary

Wavefield-extrapolation methods can produce Angle-Domain Common-Image Gathers (ADCIGs). These ADCIGs are a function of the half-aperture angle, that is, the average between the incidence angle and the reflection angle. This chapter presents a method to compute ADCIGs for converted-wave data (PS-ADCIGs) after imaging with wave-equation migration. The method exploits the robustness of computing 2-D isotropic single-mode ADCIGs, and incorporates both the P-to-S velocity ratio ($\gamma$), and the local image-dip field. This method also maps the final PS-ADCIGs into two different angle-domain common-image gathers, the first ADCIG is function of the P incidence angle, the second one is function of the S reflection angle. Results with both synthetic data and real data show the practical application for converted-wave angle-domain common-image gathers. The main contribution of this chapter is independent of the migration algorithm implemented. The approach is valid as long as the migration algorithm is based on wavefield downward continuation, and the final prestack image is a function of the horizontal subsurface offset.