Converted wave modeling of azimuthally anisotropic media: Pre‐stack evaluation of constant rotation and shift operators for layer stripping

Abstract

Prestack layer stripping was applied to azimuthally anisotropic (HTI and TTI) synthetic seismic data sets for evaluating constant rotation and shift operators. Equivalent isotropic models were compared to layer‐stripped anisotropic models using RMS amplitude and shear‐wave splitting time difference maps to quantify and qualify the error. It is found that in HTI media layer‐stripped radial and transverse components exhibited incorrect symmetry and orientations, and there are significant distortions in the amplitudes that could adversely affect inversion and/or AVO and AVAZ analysis. However, layer‐stripped PS1 and PS2 components exhibit the correct symmetry and orientation even though their amplitudes are incorrect. Time differences between PS1 and PS2 are computed using a cross‐equalization spectral analysis. This problem has been studied extensively for vertical fractures (HTI media) and post‐stack layer‐stripping analyses; therefore this study includes an equivalent model with dipping fractures (TTI media). The results from an application of the same cross‐equalization method are also applied to a receiver gather from the Teal South data set in the Gulf of Mexico. Results are found to match those of previous studies in terms of both time differences and symmetry orientation.