ИСТИНА

We present results of theoretical modeling related to reflectivity and attenuation occurring at seismic frequencies in anisotropic rocks due to the presence of aligned fluidfilled fractures. The attenuation is assumed to be caused by the Krauklis waves arising in thin fractures at low frequencies. The modeling is based on the effective medium theory. The Krauklis waves are incorporated by introducing a “Krauklis substance” whose properties are derived from the velocity of viscoelastic Krauklis wave. The Krauklis substance is pure elastic in compression but viscoelastic in shear. The viscoelastic properties of this substance depend on the mineral matrix, fluid density, fluid viscosity and the absolute value of fracture opening (not on the aspect ratio only like in the methods of effective medium theory). This gives an opportunity to analyze a dependence of the effective viscoelastic characteristics on these parameters that are of practical importance, for example, in detecting hydrocarbonbearing zones and monitoring hydraulic fracturing. In our work we mostly concentrate on the effects related to P-wave reflectivity and attenuation since this wave is commonly analyzed in practice.