Poststack migration of P-SV data

Mark Paul Harrison

This paper deals with the application of poststack migration to P-SV data. It is shown that P-SV diffractions in a vertically-inhomogeneous medium are hyperbolic to first order, and an expression for their migration velocity can be obtained. The resulting velocities are 6-11% less than the P-SV RMS velocities. In synthetic P-SV data it is found that asymmetric dispersal creates a strong splitting of diffraction tails at shallow depths. This splitting is removed by application of depth-variant P-SV DMO. Migration of the DMO-corrected synthetic P-SV stack data using a conventional phase-shift algorithm and the migration velocity function adequately collapses diffractions, whereas migration using the RMS velocity function gives significant overcorrection.