VIVA

Enables dense, high-resolution anisotropic velocity analysis using 1D inversion

VIVA visually interactive time-domain anisotropic seismic velocity analysis is an approach to both interactive and automated vertical transverse isotropy (VTI) anisotropic time-domain velocity analysis. It is used for generating Kirchhoff prestack time migration (PSTM) velocity models, providing postmigration dense anisotropic velocity updates, creating accurate velocities for pore pressure prediction studies, and estimating initial anisotropic parameters as a starting point for depth imaging workflows.

Results in more accurate images and interpretation and inversion

While conventional approaches that rely on deriving effective parameters can result in incorrect estimates, VIVA analysis directly generates interval velocity and anisotropy (interval eta) parameters. The result is more accurate images and subsequent interpretation and inversion. The interval parameter outputs from VIVA analysis complement our Kirchhoff PSTM and provide a better starting point for an initial velocity model building workflow.

The VIVA analysis workflow is similar to a traditional common image point (CIP) tomography approach and built around a new 1D layered travel-time inversion method. The technique performs a direct nonlinear inversion of P-wave reflection travel times in layered VTI media to produce interval short-spread moveout velocity (Vpn) and horizontal velocity (Vpx). Accurate ray tracing using real earth model properties rather than effective parameters is a key requirement for achieving accuracy over the wide angles needed to estimate anisotropy.

VIVA analysis and Kirchhoff PSTM may not always be appropriate. In areas of strong structural and velocity complexity, the assumptions of time imaging methods break down. In these cases the use of a depth imaging approach should be considered.