Enhanced Angular Illumination from Separated Wavefield Imaging (SWIM)

Abstract

In exploration geophysics, both primaries and multiples can be used for depth imaging. This is feasible after applying wavefield separation to generate up-going and down-going wavefields. The separated wavefields can be used as boundary data for migration using sea surface related multiples – Separated Wavefield Imaging (SWIM). The areal source (recorded down-going wavefield) in SWIM covers larger surface spread than the point source in primaries imaging. Therefore, SWIM can enhance the areal illumination of subsurface and angular illumination of a point in the subsurface, especially when shots sampling is coarser. Angle gathers are generated from imaging of primaries and SWIM. As expected, the SWIM angle gathers prove to be denser, and less affected by coarse source sampling than the primaries angle gathers. The concept is illustrated by using a wide azimuth (WAZ) field data example.