Transversely isotropic phase velocity analysis from slowness estimates

Abstract

A technique is developed for computing transversely isotropic phase velocities over intervals less than the dominant seismic wavelength. Independent estimates of vertical and horizontal slowness are made for each receiver depth and source offset pair. These provide the magnitude and direction of phase velocity for calculating the in situ elastic properties of a transversely isotropic medium. This technique requires the assumption of lateral homogeneity and factors that violate this assumption such as source elevation differences and dipping layers are evaluated with synthetic data. Six impulsive source P wave offset vertical seismic profiles (VSPs) in a 663-m well in east Texas are analyzed and a near offset SH wave vibrator VSP provides vertical shear wave phase velocities. -from Author