oa Relating Horizontal Resolution and Bandwidth after Migration

Before migrations, horizontal resolution in seismic data is a function of both frequency and depth to target. After migration, the dependence of horizontal resolution on depth is removed, resulting from the collapse of the Fresnel zone to a smaller region. The horizontal extent of this smaller region Is predicted by plane wave theory to be controlled by the predomtnant frequency and the migration aperture. An essential point is that the presence of high frequencies in the wavelet (above the noise level) is important not just to the vertical resolution (which is relatively unaffected by migration) but also to the post-migration horizontal resolution. In order to experimentally verify this point, we collected physical-model seismic data over a model that had a variety of horizontal scale lengths. The data, which originally contained high frequencies, was low-pass filtered and the time-slices from high frequency and low frequency 3D seismic volumes were compared. The resolution losses are well explained by the predictions of plane wave theory.