Depth Migration and Model Building in HTI Media using an Equivalent VTI Approach

Abstract

Wide- and multi-azimuth seismic data acquisition has become popular in the hydrocarbon industry. However, the presence of azimuthal anisotropy in the subsurface can severely affect the wide-azimuth data, and how to account for azimuthal anisotropy during the processing of wide- and multi-azimuth data remains a challenge. Here, assuming weakly horizontal transverse isotropy (HTI), we present a simplified approach to fill this gap. Under the weak anisotropy assumption, we can use an equivalent VTI medium to model a fixed azimuth of a HTI medium for P-wave propagation. Therefore, we may use the VTI algorithms for migration and depth model building in HTI medium. The anisotropic parameters of the HTI medium can also be inverted from the equivalent VTI parameters of two orthogonal azimuthal planes.