Prestack depth migration of primary and surface‐related multiple reflections

Abstract

Surface‐related multiples may severely contaminate multicomponent seabed seismic recordings. Because conventional imaging techniques require input data that consist of primary reflections only, significant processing effort is commonly dedicated to attenuating multiples prior to migration. On the other hand, surface‐related multiples provide additional illuminations of the subsurface. We present a prestack depthmigration method that allows primary and multiple reflections to be imaged simultaneously. Depth imaging with primary and multiple reflections (DIPMR) involves decomposing the data into up‐ and downgoing wave constituents, followed by downward extrapolation. Artifacts generated by interference of up‐ and downgoing events not associated with the same subsurface reflection points (cross‐talk) are attenuated using a 2D deconvolution imaging condition. In contrast to existing methods, DIPMR does not require a priori information about the source signature or directivity, because the illuminating source wavefield is extracted directly from the data themselves via the up/down separation. Moreover, there is no need for elimination or identification of multiples prior to migration. By including surface‐related multiples in the imaging procedure, the effective source wavefield is stronger and the spatial aperture wider.