Novel wide-angle AVO attributes using rational function

Abstract

Conventional AVO inversion employs Zoeppritz equations and various approximations to them to obtain the reflection coefficients of plane-waves, which are confined to a certain (small) angle range (mostly below $$40^{\circ }$$). However, near the critical angles (wide-angle), reflections at the post-critical angles provide much more potential for velocity and density inversion because of the large amplitudes and phases-shifted waveforms, while the Zoeppritz equations are not applicable anymore. Hence, there is a strong demand for the research into wide-angle AVO. With reflection coefficients at wide-angle corresponding to the features of rational function, we try to approximate the seismic data with vector fitting which is used to obtain the rational zero-pole and residual properties of wide-angle AVO. We apply this technique to classify AVO type and recognize the lithology. Our experiment shows that extending our research into wide-angle AVO is very promising in gathering richer data for a more accurate seismic analysis.