Seismic History Matching in Fractured Reservoirs Using a Consistent Stiffness-permeability Model – Focus on the Aperture

Abstract

This paper proposes a method for characterization of naturally fractured reservoirs by quantitative integration of seismic and production data. The method is based on unified (T-matrix) model for the effective hydraulic and elastic properties of fractured porous media and a (nonlinear) Bayesian method of inversion which provides information about uncertainties as well as mean (or maximum likelihood) values. We consider a fractured reservoir as a porous medium containing a single set of vertical fractures characterized by an unknown fracture density, azimuthal orientation and aperture. We then look at the problem of fracture parameter estimation as a nonlinear Bayesian inverse problem and try to estimate the unknown fracture parameters by joint inversion of seismic AVAZ data and dynamic production data. Once the fracture parameters have been estimated the corresponding anisotropic stiffness and permeability can be estimated using consistent models. A synthetic example is provided to explain the workflow. It shows that seismic and production data complement each other, in the sense that the seismic data resolve a non-uniqueness in the fracture orientation and the production data helps to recover the true fracture aperture and permeability, because production data are more sensitive to the fracture aperture rather than the seismic data.