Determining p-wave azimuthal anisotropy from walkaround vsp with offset dependent slowness corrections

Abstract

A method comprises obtaining vertical seismic profile (VSP) data using seismic sources positioned at corresponding shot locations at desired offsets from seismic receivers positioned in a borehole drilled through a formation. The method further comprises receiving seismic waves emanating from the seismic sources, processing the VSP data to determine vertical slowness of the formation, and analyzing an azimuthal anisotropy of the formation. This is performed by calculating modified total slowness of the formation using the vertical slowness and vertical polarization angle, calculating and applying a polar anisotropy correction to the modified total slowness to obtain a corrected value of the modified total slowness, and normalizing the corrected modified total slowness to a desired polarization angle. The method further comprises estimating azimuthal anisotropy based on the corrected value of the modified total slowness, outputting an anisotropy depth profile of the formation, and performing borehole operations based on the anisotropy depth profile.