VTI介质试射射线追踪

VTI medium test-firing ray tracing

本文用三次样条函数描述地层界面,用Thomsen参数描述速度各向异性,建立层状各向异性模型,采用经典的试射法实现VTI介质射线追踪。文中详细讨论了试射角估算,相速度及群速度计算,透、反射处理,线性收敛计算,反射系数计算等关键技术,推导了VTI介质入射角、透射相角、反射相角的表达式。VSP射线追踪测试表明,入射角、透射相角、反射相角表达式准确,该方法收敛快、精度高、动力学计算准确,具有普适性,可推广至TI介质。

In this paper the cubic spline function was used to describe the formation interface,the Thomsen parameters was utilized to describe velocity anisotropy,then the layered anisotropy model was established and the classic test firing method was used to realize VTI medium ray tracing.In this paper estimation of test firing angle,calculation of phase velocity and group velocity,processing of transmitted and reflected waves,reflection coefficient calculation and other key techniques were discussed in detail,the expressions of the incidence angle for VTI medium,the transmission phase angle,and the reflection phase angle were derived.The VSP ray tracing test shows that the expressions of the incidence angle for VTI medium,the transmission phase angle,and the reflection phase angle were accurate,the algorithm could converge fast with high precision,its dynamics calculation was accurate,so with its excellent universality it can be applied to the TI medium.