裂隙各向异性介质中的NMO速度

推导了各向异性介质中由弹性系数表示的方位动校NMO速度的具体表达式,表明各向异性介质中方位NMO速度程椭圆形状,并分别对具水平对称轴的横向各向同性介质(HTI)、正交介质和单斜各向异性介质及在不同的裂隙填充物的性质下方位NMO速度进行了计算,结果表明裂隙的存在对NMO速度的影响不仅与裂隙密度有关,还取决于裂隙填充物的性质.同时,研究表明对于裂隙型单斜各向异性介质,其方位NMO速度椭圆轴向并不象HTI介质和正交介质中的那样与自然坐标系的坐标轴一致,而是发生了一定角度的偏离,其大小与裂隙填充物的性质、两组裂隙密度的比值及裂隙间的夹角等因素有关,研究结果为进一步区分裂隙介质的类型及裂隙填充物的性质提供依据.

NMO velocity in fractured anisotropic media

The NMO velocity equations described with elastic constants have been deduced.And then the azimuthally NMO velocities in horizontal transverse isotropy(HTI),orthorhombic and monoclinic fractured media have been calculated with different property of fracture infill.The computation results shown that the azimuthally NMO velocity in anisotropic media shows an ellipse with respect to the coordinate axes and it is affected not only by fracture density but also by the property of fracture infill.The study has also shown that there is a rotation angle for azimuthally NMO velocity ellipses in monoclinic media which different form HTI and orthorhombic media.The rotation angles of NMO ellipses are related to the property of fracture infill,fracture density ratio and the angle between the two fractures.These research results can be used to identify the type of fractured media and the property of fracture infill.