A damage domain approach to integration of geomechanics and seismic anisotropy for fractured reservoir characterization

Abstract

AbstractThe concepts of damage mechanics are proposed as the logical basis for integration of seismic anisotropy based identification and geomechanics based prediction of subsurface fracturing. In such a context a damage tensor can be used to describe the evolution of (anisotropic) degradation of the elastic properties of a rock undergoing deformation. The concepts of damage mechanics are common to both geomechanical and seismic descriptions of rock elasticity but have not previously been connected. In geomechanical simulations of the evolution of geological structures, damage development can be predicted, described and recorded through a single damage tensor representation for each point in the model (with the inclusion of damage by a number of different mechanisms). With appropriate analysis, equivalent information may be determined from anisotropy analysis of seismic reflection data as the seismic wave propagation is sensitive to the total damage. Thus the proposed approaches for parameterization and modelling/analysis, using the damage domain, provide a common quantification of the damage (as detected using seismic data and predicted using geomechanical modelling) that permits integration of the two disciplines. This paper presents the damage-domain theory and linkage between the domains plus practicalities, with respect to both the geomechanical and seismic analyses, with illustration using a simple geomechanical model example.