HTI介质饱和流体特性和裂缝密度对方位反射系数的影响

Influence of HTI medium saturated fluid properties and fracture density on azimuthal reflectivity

结合等效介质理论和Thomsen裂缝理论构建了饱和流体HTI介质弹性矩阵并推导出HTI介质弹性波反射/透射方程,基于该方程讨论了流体类型及裂缝密度对方位反射系数的影响。模型试算结果表明:下伏HTI介质饱含气和饱含水之间的方位反射系数差异比饱含油和饱含水之间的明显,饱含气和饱含水反射系数的差异随着入射角增大而增大,随方位角增大而减小;裂缝密度越大反射系数越小,不同裂缝密度的反射系数差异随着入射角和方位角增大而增大。研究结果为利用方位地震反射特征检测裂缝密度和流体性质提供了理论依据。

We build saturated fluid HTI medium elasticity matrix with equivalent medium theory and Thomsen fracture theory,and derivate elastic wave reflection-transmission equation of HTI media.Based on the equation,we discuss how fluid type and fracture density impact azimuth reflectivity.Model tests indicate that it is easier to distinguish differences of azimuth reflectivity between gas and water layer than that of oil and water layer.Furthermore,the larger incident angle causes the bigger reflectivity difference between gas and water layer and the larger azimuth angle causes the smaller that of difference.When fracture density increases,reflectivity decreases.The larger incident angle and the larger azimuth lead to the bigger reflectivity difference of different fracture density.The research can provide theory basis for fracture and fluid detection by azimuth seismic reflection characteristics.