Generalized velocity approximation

Abstract

We have developed a new approximation for P-wave velocity that has the same functional form for phase and group velocities. We call it the generalized velocity approximation (GVA) because it is similar to the generalized moveout approximation. The 2D GVA has five parameters, and the 3D GVA has 12 parameters. Our approximation is exact for the phase velocity in a transversely isotropic medium. The parameters of the 3D version of the proposed approximation are defined in all of the symmetry planes in the same fashion. Numerical examples indicate that our approximation has the same accuracy as recently proposed anelliptic approximation, but it has fewer parameters.