Kinematic Artifacts in Prestack Depth Migration

Strong refraction of waves in the migration velocity model introduces kinematic artifacts coherent events not corresponding to actual reflectors into the image volumes produced by prestack depth migration applied to individual data bins. Because individual bins are migrated independently, the migration has no access to the bin component of slowness. This loss of slowness information permits events to migrate along multiple incident-reflected ray pairs, thus introducing spurious coherent events into the image volume. This pathology occurs for all common binning strategies, including common source, common offset, and common scattering angle. Since the artifacts move out with bin parameter, their effect on the final stacked image is minimal, provided that the migration velocity model is kinematically correct. However common image gathers may exhibit energetic primary events with substantial residual moveout, even with kinematically accurate migration velocity model. ∗Centre de Mathématiques, Ecole Polytechnique, 91128 Palaiseau Cedex, France, email [email protected] †The Rice Inversion Project, Department of Computational and Applied Mathematics, Rice University, Houston TX 77005-1892 USA, email [email protected]