An Equivalent Medium for Fractured Carbonate Reservoirs

摘要

Approximately 50% of the world’s known hydrocarbon reserves are contained in carbonate rocks; therefore, wave studies on fractured carbonate reservoirs are very important for application in exploration activities. In this paper, we present a fractured porous equivalent medium to describe fractured carbonate reservoirs in oil seismic exploration frequency bands (<100Hz). Fractures are described in terms of fracture-induced anisotropy, and they are embedded in a porous background. Then we use Biot’s equations of poroelasticity and anisotropic Gassmann equations to derive the effective constants of the equivalent medium. It is shown that the fractures and pores strongly influence wave propagation, induce anisotropy and cause poroelastic behaviour in the wavefields. We observe that the presence of fractures gives rise to changes in phase velocity and attenuation.