Azimuthal seismic inversion for fracture weaknesses based on facies constraint

Huaizhen Chen, Jian Han, Kristopher A. Innanen

A two-step inversion method of employing azimuthal seismic data to estimate fracture weaknesses constrained by fracture facies constraint is proposed. Firstly, based on the PP-wave reflection coefficient and azimuthal elastic impedance (EI) derived in terms of elastic properties, density and fracture weaknesses, we use a Bayesian Markov chain Monte Carlo (MCMC) algorithm to estimate EI of different incidence angles and azimuths, and predict fracture facies using the estimated EI. Secondly, we use the fracture facies to construct a more accurate initial model of unknown parameters and use the estimated EI of different incidence angles and azimuths as the input to estimate unknown parameters. Employing noisy seismic data of signal-to-noise ratios (S/N), we verify the robustness of the proposed inversion method.