Wide-azimuth angle gathers for wave-equation migration

Conclusions

Angle decomposition based on wavefield extrapolation methods is characterized by robustness in areas with sharp velocity variation and by accuracy in the presence of steeply dipping reflectors. Extended common-image-point gathers constructed at discrete image points provide sufficient information for angle decomposition. The decomposition is based on the planar approximation of the source and receiver wavefields in the immediate vicinity of the image points. Both space-lag and the time-lag extensions are required to completely characterize the reflection geometry given by the local reflection and azimuth angles. However, assuming that information about the reflector slope is available, we could avoid computing one lag of the extended image, usually the vertical. This increases the computational efficiency of the method and makes it affordable for large-scale wide-azimuth imaging projects.