三维复杂介质中转换波走时快速计算

FAST CALCULATION OF CONVERTED WAVE TRAVELTIME IN 3-D COMPLEX MEDIA

复杂介质中转换波走时计算是多波勘探地震学中重要内容之一 .本项研究利用惠更斯原理和费玛原理 ,获得了三维复杂介质中转换波快速计算的改进型最小走时树方法 .其中 ,在保证精度的条件下 ,为了提高三维转换波走时计算效率 ,首先对初至波最小走时树基本算法进行了改进 .本方法通过将转换波分为上、下行波分别进行射线追踪以实现三维转换波走时的快速计算 .模型计算表明 ,方法的计算速度快 ,而且稳定性强 。

It is one of important subjects of multiwave exploration seismology to calculate traveltimes of converted waves in complex media.This paper puts forward an improved minimum traveltime tree algorithm for fast calculation of traveltimes of converted waves in 3-D complex media, which is based on Huygens' principle and Fermat's principle.First,we improve the basic minimum traveltime tree algorithm for first-break waves in order to speed calculation of 3-D converted wave traveltimes.Second,we extend the improved algorithm for first-break waves to converted waves by separating converted waves into downward and upward traveling waves and tracing them, respectively.The numerical example shows that the method preseated in this paper for calculating converted wave traveltimes is fast and robust,and can be applied to practical multiwave seismic exploration.