基于波前重建和李代数积分的地震波走时计算  

Seismic Travel-Time Calculation Based on Wave-Front Construction and Lie Algebra Integral

作　　者：张廉萍[1] 刘洪[1] 

机构地区：[1]中国科学院地质与地球物理研究所/油气资源研究重点实验室,北京100029

出　　处：《吉林大学学报（地球科学版）》2010年第6期1463-1470,共8页Journal of Jilin University：Earth Science Edition

基　　金：国家重点基础研究发展计划项目(2007CB209603);国家自然科学基金面上项目(40674072);国家自然科学基金重点项目(40774069)

摘　　要：地震波走时计算在数值模拟、层析反演和偏移成像中均有重要意义。将波前重建与李代数积分相结合,提出了一种新的适应横向变速介质的非对称走时算法,称之为wave-front construction-Lie algebra integral(WFC-LAI)算法。本算法利用一次波前重建计算成像射线走时进行坐标变换,将深度域单平方根算子透镜项转化为常数,在射线坐标系下计算李代数积分和指数映射,得到地震波走时的解析表达式。数值试验表明,该方法计算结果与线性横向变速介质中走时的理论值吻合。通过与波前重建结果对比,WFC-LAI算法对于求取横向变速介质中地震波走时是可行的,节省了存储空间,易于并行,有利于提高Kirchhoff积分叠前深度偏移的精度和效率。Seismic travel-time calculation is significant in numerical modeling,tomography inversion and migration.In this paper,integrated using wave-front construction and Lie algebra integral,we proposed a new method,called wave-front construction-Lie algebra integral（WFC-LAI）method,which is applicable to unsymmetrical travel-time calculation in laterally velocity variant medium.We make coordinate conversion by travel-time of image rays computed by wave-front construction and convert the lens item of single square root operator in depth domain to a constant,then in the ray coordinates we determine analytical expression of paraxial travel-time using Lie algebra integral and exponent mapping.Through numerical experiments we know our result coincides with the theoretical value in the medium with linear laterally variant velocity.Comparing with wave-front construction we can conclude that in laterally velocity variant medium,WFC-LAI method is applicable to travel-time calculation and saves storage space and computing time,which is extremely beneficial to improve the precision and efficiency of Kirchhoff pre-stack depth migration.

关 键 词：横向变速 李代数积分 指数映射 波前重建 非对称走时 地震 

分 类 号：P631.4[天文地球—地质矿产勘探]