Overview

Migration in the angle-domain creates seismic images for different reflection angles. This chapter presents a method for computing angle-domain common image gathers from seismic images obtained by depth migration using wavefield extrapolation. This method operates on prestack migrated images and produces the output as a function of the reflection angle and not as a function of offset ray-parameter as in other alternative approaches. The method amounts to a radial-trace transform in the Fourier domain and is equivalent to a slant stack in the space domain. Thus, we obtain angle gathers using a stretch technique that enables us to impose smoothness through regularization. This method is accurate, fast, robust, and easy to implement. The main applications of this method are in the migration velocity analysis and amplitude versus angle analysis. This chapter develops the angle gather transformation in 2D.