Evaluation and joint inversion of TTI velocity models with walk-away VSP

Abstract

Anisotropic model building is critical to the success of a prestack depth migration (PSDM) project. Well data are essential in developing the anisotropic models for these seismic PSDM projects. We present a case study where a multitude of walk-away VSP (WVSP) data was used in evaluating the accuracy of the anisotropic velocity models. In particular, we integrated the WVSP travel times with the surface seismic PSDM residual moveout measured in migrated common image gathers (CIGs), in the joint inversion of the anisotropic model parameters. The resulting anisotropic model significantly reduces the misties between the modeled and observed first arrivals in the various WVSP lines, in addition to much flattened CIGs and significant improvement in imaging.