扩展矩形盒波前法与扩展波前法在初至波计算中的对比研究  

Comparison on the rectangular box wavefront method and the expanding wavefront method in first-arrival traveltime calculation

作　　者：张智 任琴琴[1,2] 孙维昭 何达喜[1,2] 唐国彬 王敏玲 王洪华 郭桂红[4] ZHANG Zhi;REN Qin-qin;SUN Wei-zhao;HE Da-xi;TANG Guo-bin;WANG Min-ling;WANG Hong-hua;GUO Gui-hong(Cooperative innovation center for exploration and material development of concealed non-ferrous metal deposits in Guangxi,Guilin university of technology,Guilin,Guangxi,541004;Key laboratory for exploration of concealed metal minerals in Guangxi,Guilin university of technology,Guilin,Guangxi,541004;Geophysical Research Institute of BGP INC,CNPC,Zhuozhou 072750,China;Key Laboratory of Mechanics on Disaster and Environment in Western China,Lanzhou University,Lanzhou 730000,China)

机构地区：[1]桂林理工大学广西有色金属隐伏矿床勘查及材料开发协同创新中心,广西桂林541004 [2]桂林理工大学广西隐伏金属矿产勘查重点实验室,广西桂林541004 [3]中国石油集团东方地球物理勘探有限责任公司研究院,河北涿州072750 [4]兰州大学西部灾害与环境力学教育部重点实验室,兰州730000

出　　处：《桂林理工大学学报》2018年第4期718-725,共8页Journal of Guilin University of Technology

基　　金：国家自然科学基金项目(41574078; 41274070; 41604102; 41604039);广西自然科学基金项目(2016GXNSFBA380082; 2016GXNSFBA380215; 2018GXNSFAA138059);广西壮族自治区地质资源与地质工程"八桂学者"经费专项(2013);广西有色金属隐伏矿床勘查及材料开发协同创新中心创新团队项目(GXYSXTZX2017-Ⅱ-5)

摘　　要：基于Vidale "扩展矩形盒波前法"的思想,通过有限差分求解程函方程,利用MATLAB编程计算了二维速度模型的初至时间。理论研究和模拟结果表明:扩展矩形盒波前法计算初至时间不会像射线追踪法一样出现盲区,具有较高的计算精度,可大大降低计算量;但在处理复杂结构模型和强速度界面时会出现不稳定现象,导致所计算的走时并非真正的初至时间。为了进一步提高计算精度、算法的稳定性和解决地震波传播的因果性问题,给出了结合局部算法的扩展波前法结果。由于扩展波前法结合局部算法遵循了因果性,适应复杂结构模型和强速度界面,但计算的大量时间要用于寻找波前上的最小初至时间,效率较低。Traveltime calculation plays an important role in many areas of seismology,such as pre-stack migration,traveltime inversion,earthquake location and seismic tomography.In this paper,the author gets traveltime by solving eikonal equation with finite difference method.Based on Vidale expanding square wavefront idea,the traveltimes of first arriving seismic waves are computed through the forward modeling by programming with MATLAB software in two dimensions.Modeling computation shows that the“expanding square”method overcomes many problems of the ray tracing calculation,like shadow zones,with higher accuracy and improves computing efficiency.But this method isn’t applicable to media with strong velocity contrast and complex velocity structure.Sometimes the computational traveltimes of the first arriving seismic waves with this method isn’t real first arriving time,for it violates the causal laws.To improve the computational accuracy,the algorithm stability and to solve the causality of the propagating path of seismic waves,the paper presented a finite-difference scheme in which the solution region progresses outward from an“expanding wavefront”rather than an“expanding square”in combination with local algorithm.However,the expanding wavefront method is applicable to media with strong velocity contrast and complex velocity structure,which made the algorithm more robust and accuracy.But penalty results to a large increase in computational cost and programming effort.A lot of computing time wastes in finding the minimum travetimes of the first arriving seismic waves.

关 键 词：扩展矩形盒波前法 扩展波前法 程函方程 有限差分 初至走时 

分 类 号：P631.41[天文地球—地质矿产勘探]