Abstract：The attenuation and dispersion of seismic wave occur when seismic wave propagates in patchy saturated medium containning stiff and soft pores because of fluid flows of different scales.And the fluid flows of different scales are interacted each other.Considering interaction of fluid flow at microscopic and mesoscopic scales,we derive in this paper a new seismic attenuation model,double-scaled model,based on Biot thoery,provide expressions of solid phase displacement induced by fluid flow,elastic modulus,phase velocity and attenuation coefficient,and compare them with that of the layered pathcy saturation model.At the same time we analyze influences of the modified wet modulus and different reservoir physical parameters on seismic wave attenuation based on the double-scaled model.It suggests that the modified wet frame increases rock frame stiffness,decreases solid phase displacement induced by mesoscopic fluid flow at interface between two layers,and strengthens velocity dispersion and attenuation,which interpretates the interaction mechanism between microscopic squirt flow and mesoscopic fluid flow.There are two or three "dispersion steps" in the frequency band when two layers are saturated with different types of fluid,and microscopic squirt flow and mesoscopic fluid flow can work in the same frequency band.P-wave attenuation peak increases and moves toward low frequency with water saturation increase. While water saturation becomes larger,attenuation decreases and its peak moves toward higher frequency, and velocity inceases with water saturation increase.
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