基于体元模型的三维VSP射线追踪

本文基于费马原理,利用全路径迭代算法实现体元模型中的三维VSP两点射线追踪。体元模型由块体组成,块体之间界面采用连续函数或离散点插值表示。射线追踪过程中先对中间路径点给一初始值,通过迭代求解有关路径修正量的矩阵方程,得到满足精度的路径点信息。文中对三维VSP观测系统采集进行正演,并针对目的层的反射P波和P-SV波射线追踪结果说明该方法对块体模型的适应性,射线追踪精度可根据研究问题的需要确定,可作为三维VSP观测系统参数优化设计的辅助手段。

3-D VSP ray-tracing based on volume element model

Based on Fermat's principle, the paper uses full-path iterative algorithm to realize 3-D VSP two-point ray tracing in volume element model. The volume element model is composed of blocks, in which the interfaces between blocks represent by continuous function or interpolation at discrete points. The initial value is firstly given for the points of intermediate paths during ray tracing, then the matrix equation of revised values is computed by iterative algorithm, which gains the information with satisfied precision at path points. The paper implements forward modeling for acquisition in 3-D VSP geometry and illustrates the adaptability of the method to block model by ray-tracing results of reflection P-wave and P-SV waver on the targets. The ray-tracing precision can be determined according to researched needs. The method can act as auxiliary tool of optimum designing the parameters of 3-D VSP geometry.