Seismic Wave Field Modeling And Character Analysis Of Two-phase Viscoelastic EDA Media

With the development of the exploration and exploitation of oil and gas in our country, the degree of the development of the exploration and exploitation of oil and gas has deepened. The exploration object we faced have changed to complex structural reservoirs, lithological reservoirs and fractured reservoirs. Therefore, considering two-phase, viscoelasticity and anisotropy, establishing more exacter model of underground media and making the study of seismic wave propagation theory had great important practical significance for explanation of practical seismic data and improvement of the wave propagation theory in complex media.Based on anisotropy theory, viscoelasticity theory and Biot theory, we introduce carcione viscoelastic mechanism into matrix of two phase media which has vertical fracture, and establish wave equation of two phase viscoelastic EDA media. We also can obtain elastic parameters of two phase viscoelastic EDA media by Hudson theory. What's more, wave field modeling of homogeneous and two-layer viscoelastic media and two phase viscoelastic media is carried out using pseudo-spectral method. Comparing with viscoelastic isotropic media, elastic EDA media, two phase EDA media and two phase viscoelastic isotropic media, some characters of anisotropy of media which make the wavefront of qP wave and qSV wave be different from that of isotropic media can be observed by snapshot, particle velocity vector figures, particle vibration figures and seismic records. And the configuration of wavefront of qSV wave with sharp area is more complex than qP wave's. Viscoelasticity of media could result in attenuation of seismic wave amplitude. We can observe slow P wave except for qP wave and qSV wave in two phase media and the phenomenon that longitude of slow qP wave in fluid phase is bigger than qP wave and qSV wave in solid phase, while in fluid phase, the opposite is true. The vibration direction of qP wave is perpendicular to wave front, the vibration direction of qSV wave which is more complex than that of qP wave is showing a trend of being parallel to the wave front. For slow P wave, the vibration of it is perpendicular to wave front on the whole. In the modeling results of two layers two-phase viscoelastic EDA media, we can get more wave field information from reflection waves, refractions waves, reflection converted waves and refraction converted waves except direct waves. The results indicated that two phase viscoelastic EDA media can reflect multiphase, viscoelasticity and anisotropy, and it is something of value in the theory and practice to exploration and study on fractured reservoirs.