对旅行时进行抛物型插值的地震射线追踪方法  

Seismic ray-tracing method of applying parabolic Interpolation to travel-time

作　　者：张赛民[1] 周竹生[1] 陈灵君 周惠群 

机构地区：[1]中南大学信息物理工程学院,长沙410083 [2]中石化中南分公司研究院,长沙410007

出　　处：《地球物理学进展》2007年第1期43-48,共6页Progress in Geophysics

摘　　要：提出一种对旅行时进行抛物线插值的地震射线追踪方法(简称PTI方法),它比基于旅行时线性插值方法(简称LTI方法)计算结果更准确.PTI和LTI方法都是基于2D网格单元模型,用于计算地震波的旅行时和射线路径.首先介绍了相关方法的一些基本概念.旅行时和射线路径都是在网格边界上进行计算的,因此,射线路径在同一恒速网格内是直线.其计算过程有两步.第一步,计算旅行时,第二步追踪射线路径.然后给出了LTI算法的基本公式.因为在炮点网格内可能存在折射波,文章也相应导出了其公式.最后详细推导了PTI方法的公式.通过模型试算对比说明,用PTI方法较LTI算法更精确、更有效,PTI方法是一种很有发展前途的地震射线追踪算法.A new seismic ray-tracing method was put forward based on parabolic travel-time interpolation （PTI） method, which is more accurate than the linear travel-time interpolation （LTI） method. Both PTI method and LTI method are used to compute seismic travel-times and ray-paths in a 2D gridded cell model. Firstly, some basic concepts related are introduced. The calculations of travel-times and ray-paths are carried out only on cell boundaries. So, the ray-path is always straight in the same cells with uniform velocity. Two steps are applied in the PTI and LTI method. Step 1 computes travel-times and step 2 traces ray-paths, then, the derivation of LTI＇formulas process is described. Because of the presence of refraction wave in shot cell, the formula aiming at shot cell is also derivate. Finally, through the comprehension of above-mentioned works, the PTI method is presented. The calculations are more complex than that of LTI method, but the error is limited. Results of numerical model show that the PTI method can trace ray-paths more accurately and efficiently than LTI method does.

关 键 词：PTI法 LTI法 射线追踪 旅行时 射线路径 网格单元 

分 类 号：P315.3[天文地球—地震学]