旋转轴对称弱各向异性介质模型的射线追踪方法  

Ray tracing method for rotating axisymmetric weak anisotropic media

作　　者：张志伟[1,2] 何淑平[1] 杨长春[1] 陈雨红[3] 

机构地区：[1]中国科学院地质与地球物理研究所,北京100029 [2]中国石油勘探开发研究院,北京100083 [3]中国科学院地质与地球物理研究所兰州油气资源研究中心,兰州730000

出　　处：《地球物理学进展》2013年第6期3237-3242,共6页Progress in Geophysics

摘　　要：对我国西部复杂地表、地下进行地震波成像时,需要采用旋转轴TI介质kirchhoff偏移和层析反演技术,这些技术需要完成大量射线追踪工作.在各向异性介质中,地震波的群速度与相速度具有不同的方向,地震波按群速度的方向传播,而不是沿相速度的方向传播,群角表示了能量传播方向,在实际中很难测量与计算.但由于大多数岩石具有弱各向异性,从而大大简化了相速度的表达式.本文针对旋转轴对称弱各向异性介质,从相速度的近似公式出发,通过线性近似的方法,推导出相速度偏导数和群速度的表达式.采用四阶龙格库塔、平面插值和线性插值等算法计算得到实际计算点参数,进而给出旋转轴对称弱各向异性介质中的地震波传播路径的计算方法.通过数值模拟结果,表明所给出的射线追踪算法适应性强,对旋转轴对称弱各向异性介质计算效率和准确性高.Seismic wave imaging of underground media of western China with complex surface needs kirchhoff offset tomographic inversion techniques of rotation axis TI media, these techniques are based on a large number of ray tracing work. In anisotropic media, group velocity and phase velocity have different propagation directions. The seismic wave propagates along the direction of group velocity, it does not depend on the direction of phase velocity. Ray angle is a complex function with respect to phase angle, it is difficult to measure and calculate. But most rocks are weak anisotropic, so the expression of phase velocity can be simplified greatly. Based on the approximate expression of phase velocity this thesis for rotating axisymmetric weak anisotropic media deduces an expression of the partial derivative of phase velocity and an expression of group velocity with the method of linear approximation. This paper uses the fourth order Runge-Kutta method together with the two-dimensional interpolation and linear interpolation to obtain the parameters of the physical locations. At last the paths of seismic wave in rotating axisymmetric weak anisotropic media are computed. According to the analysis of the computational results, it indicates that the method developed in this paper has strong adaptability, high computational efficiency and high accuracy for rotating axisymmetric weak anisotropic media.

关 键 词：弱各向异性 旋转轴对称 射线追踪 群速度 相速度 相角 

分 类 号：P631[天文地球—地质矿产勘探]