【摘要】 对于包含有垂向裂缝的横向各向同性地层或含有多组正交裂缝的各向同性地层,正交各向异性介质模型是最简单的与实际地层相符的方位各向异性模型.本文对单层水平反射界面正交各向异性模型采用射线追踪法计算了全方位角变化的P波走时,时距曲线表现出强方位各向异性.采用小生境遗传算法,对三条成一定角度的测线的走时信息进行速度和各向异性参数反演.模型算例表明,此方法可以得到高精度的裂缝方位角、P波垂直速度和较高精度的Thomsen各向异性参数.更多还原

【Abstract】 An orthorhombic (ORT) model is the simplest azimuthally anisotropic model used to describe realistic fractured reservoirs (e.g., vertical cracks embedded in an anisotropic background media or orthogonal fracture systems in purely isotropic matrix). In this paper, we calculate the omnidirectional reflection traveltime of P-wave in a single orthorhombic media with a horizontal interface by using the ray trace method. The reflection P-wave traveltime-distance curves show strong azimuthal anisotropy. Using the Niche Genetic Algorithms (NGA), inversion of reflection traveltime of three common-midpoint (CMP) lines provides us with a good estimation of azimuth, P-wave vertical velocity and Thomsen anisotropic parameters.更多还原