A practical approach to PP seismic angle tomography

Abstract

A B S T R A C TThe use of the differential semblance misfit function on common-image-point gathers in the angle domain lends itself to an automated tomographic approach through a gradient-based search in the model space. The velocity model is described by a layer-based model with linear velocity trends and a superimposed bicubic B-spline. The interfaces of the layer-based model are computed by map migration of the PP zero-offset traveltimes of key reflectors. The common-image-point gathers are produced by a restricted inverse generalized Radon transform or amplitude-versus-anglecompensated migration. We present a complete description of all 2.5D formulae for isotropic velocity analysis of PP reflections and the results for ocean-bottom seismic data.