Abstract：Fracture parameters play a very important role in fracture reservoir evaluation.Prestrack inversion based on azimuthal elastic impedance is an efficient approach to obtain fracture parameters.Seismic azimuthal reflection coefficient equation is the basis of azimuthal prestack inversion.In order to develop a stable fracture parameter inversion method,firstly,we analyze the sensibility of each parameter in azimuthal reflection coefficient equation and discuss the primary reasons that result in the instability of fracture parameter inversion.Meanwhile,we find that fracture parameter is the basic reason why fracture reservoirs present azimuthal difference.Then,according to the thought of perturbation inversion,the azimuthal elastic impedance can be expressed as background elastic impedance term and perturbation elastic impedance term,the second term is caused by fracture parameters.Finally,we establish a stable fracture parameter inversion method based on perturbation elastic impedance.Model and real data tests show that the introduced inversion method can obtain reasonable reservoir fracture parameters,which solves the problem of the instability of fracture parameter inversion in some way.
