Abstract：Studying anisotropy of fractural medium has important meaning for oil/gas exploration and development as well as underground engineering construction. The boundary element method is characterized by fewer input data and high precision. Based on Hudson fractural medium model, the paper creates numeric model of boundary element method that the P-wave propagates in fractural medium, simulates the influence of fractural density, aspect and infill on propagation velocity and attenuation factor,and probes the relationship between the wavelength and characteristic fractural scale. The results showed the boundary-element method can better simulate the issue of wave propagating in heterogeneous fracture-bearing medium. The wavelength-to-characteristic fractural scale ratio is an important factor whether the equivalent medium theory is correct or not, the anisotropic degree decreased when the fracture is water saturated, the fractural density has certain influence on P-wave propagation velocity and attenuation factor. Under the circumstance of seismic long wavelength, the circular dry fracture is more effective in attenuation of elastic wave than thin dry fracture when the characteristic scale is same.
