Interpretation of common-image gathers

As with AVO studies, the rock-physics interpretation of angle-domain CIGs after shot-profile migration is fraught with pitfalls: two of the most important being caused by velocity problems and sampling problems.

The first major pitfall is common to all angle-dependent reflectivity studies: if events are not correctly imaged, they will not be flat in the angle domain, and artifacts will appear in AVA interpretations. For these methods to be successful, velocities must be very well understood.

While the second major pitfall may also cause problems for other migration algorithms, geometries suitable for shot-profile migration are particularly susceptible to sampling problems on the shot axis.