Resolution of small velocity anomalies by wide azimuth reflection data tomography

Summary: Seismic velocity determination has suffered from insufficient coverage of the data acquisition. For this reason only smooth long wave length components of the velocity variation can be reliably recovered. A theoretical study has shown that multi azimuth data has the potential to significantly improve velocity determination. In this study we examine the capability of multi azimuth acquisition in resolving small velocity anomalies by means of a 3D synthetic example. The model consists of a layered structure which contains two small velocity anomalies. The study compares the resolution when the migrated gathers contain no azimuthal information to the case when the gathers are binned both according to offset and azimuth. The results show that conventional gathers can only obtain a blurred image of the velocity anomalies, whereas with multi azimuth gathers the velocity anomalies appear distinctly.