Conclusions

I presented a method to compute Common Image Gathers from reverse-time shot profile migration. The proposed method generates accurate CIGs that can be used to update the migration velocity function, both for regular reflections and for overturned reflections.

The reflections generated from either side of an interface can be discriminated by computing the crosscorrelation of the source wavefield with the receiver wavefield at the non-zero time lag. This techniques is useful for imaging both overturned reflections and prismatic reflections.

The migration of a synthetic example containing prismatic reflections suggests that imaging this kind of reflections might be prone to artifacts and may require the computation of the CIGs with the even more general imaging condition that includes vertical subsurface offset.