Quantitative inversion of azimuthal anisotropy parameters from isotropic techniques

Abstract

Exploration and development of unconventional reservoirs, where fractures and in situ stress play a key role, calls for improved characterization workflows. In this work, we present a method for quantitative estimation of anisotropic parameters related to stress and fracture detection that makes use of standard isotropic modeling and inversion techniques in anisotropic media. Based on the Rüger reflectivity equations for horizontal transverse isotropic media, we build a set of transforms that map the elastic parameters used in prestack inversion into effective anisotropic elastic parameters. When used in isotropic forward modeling and inversion, these effective parameters accurately mimic the anisotropic reflectivity behavior of the seismic data, thus closing the loop between well-log data and seismic inversion results in the anisotropic case.