Controlled-aperture wavepath-wave-equation migration

We propose a new implementation of wave-equation migration with controlled apertures determined by the wavepath migration approach. The new method, denoted as controlled-aperture wavepath-wave-equation migration, employs a two-step strategy to migrate common-shot seismic data. In the first step, an efficient wavepath migration is performed for a given shot using ray incidence angles computed directly from the data to determine controlled migration apertures. In the second step, a wave-equation migration is conducted on the shot data using the controlled apertures. For each shot, these apertures include: (1) the imaging aperture, (2) the aperture for the source-wavefield extrapolation, and (3) the aperture for the receiver-wavefield extrapolation. Compared to the uncontrolled-apertures used in conventional wave-equation migration methods, controlled apertures are much narrower and more localized, leading to a more accurate treatment of local slowness variations. Numerical results with the SEG/EAGE salt model show that the new method performs better in resolving salt boundaries and sub-salt weak reflectors than the corresponding uncontrolled-aperture migration.