Abstract

In this study we describe a different approach from the unconstrained Dix transform to convert the effective anisotropic parameters Vnmo and ?eff, coming from the nonhyperbolic velocity analysis, into interval ones. The method is designed for building and refining the velocity models for the Anisotropic PSDM (PreStack Depth Migration). The objective of this algorithm (based on a new Eni proprietary approach) is to prevent the nonrealistic and highly oscillating interval velocity and anellipticity ?int parameter, which can be easily obtained with Dix inversion from relatively small variations in the stacking or effective values. The resulting model can be considered geologically reasonable and more stable, using a combination of constraints and analytical trend.