P281 Limited-Aperture Migration by Sterotomography Output M. Alerini* (Sintef Petroleum Research) M. Riede (Now at RWE) & B. Ursin (NTNU) SUMMARY In Kirchhoff based migration the relevant information is located at the specular reflection point along the migration operator. Limiting the migration operator around this specular point not only increases the speed of the process but also improves greatly the quality of the migration results by suppressing important aliasing artifacts. The determination of the specular point is not trivial without any a priori knowledge of the geological structure. We propose here an approach that makes efficient use of the results