三维复杂黄土塬区变加密不等距网格初至走时计算与特征分析  

Travel-time calculation and characteristic analysis for first arrival in 3D complex loess plateau area using variable density and unequal distance grid

作　　者：韩令贺[1,2] 孙章庆 胡自多[1] 刘威[1] 韩复兴[3] 田彦灿[1] HAN LingHe;SUN ZhangQing;HU ZiDuo;LIU Wei;HAN FuXing;TIAN YanCan(Research Institute of Petroleum Exploration and Development-Northwest PetroChina,Lanzhou 730020,China;College for Geophysics,China University of Petroleum(Beijing),Beijing 102249,China;College for Geoexploration Science and Technology,Jilin University,Changchun 130026,China)

机构地区：[1]中国石油勘探开发研究院西北分院,兰州730020 [2]中国石油大学(北京)地球物理学院,北京102249 [3]吉林大学地球探测科学与技术学院,长春130026

出　　处：《地球物理学报》2022年第8期3108-3122,共15页Chinese Journal of Geophysics

基　　金：中石油前瞻性基础性项目(2021DJ05);国家自然科学基金项目(42074150,41404085);国家重点研发计划(2018YFC0604200)资助.

摘　　要：三维复杂黄土塬区初至走时计算与特征分析,对于分析复杂黄土塬区地震波运动学特征、观测系统设计、初至拾取及层析反演等均具有重要意义.针对该问题:首先,采用三维分区局部变加密不等距网格剖分复杂黄土塬速度模型;然后,建立基于费马原理和迎风格式的双线性插值局部走时算法,采用修正后的群推进法作为波前扩展方式;最后,以理论模型考察了算法的精度与效率、分析了三维复杂黄土塬区地震初至波的走时特征.结果表明:变加密网格策略能在增加很少计算量的情况下,大幅降低因震源奇异性引起的计算误差问题,同时还能无条件稳定且灵活的适应三维复杂黄土塬区的复杂地震地质条件;和层状均匀模型相比,黄土塬区地震初至波的走时场和时距曲线较为复杂.The travel-time calculation and characteristic analysis for first arrival in the 3D complex loess plateau area are of great significance to the analysis of the kinematic characteristics for seismic waves,the design of the seismic acquisition system,especially the first arrival picking and tomography inversion.To solve this problem:Firstly,the partition local variable density and unequal distance grid is adopted to divide the velocity model of 3D complex loess plateau;Then,a local travel-time algorithm of bilinear interpolation is established based on Fermat principle and upwind scheme and a modified group marching method is adopted as the scheme of wave-front expansion;Finally,the accuracy and efficiency of the algorithm and the characteristics of first arrival travel-time in the 3D complex loess plateau area are investigated by using the theoretical model.The results show that:We can greatly reduce the computational error caused by the singularity of the source and adapt to the complex seismic geological conditions of the 3D complex loess plateau unconditional stably and flexibly by using the scheme of variable density grid;Compared with the 3D layered uniform model,the travel-time field and time distance curve of seismic first arrival in 3D complex loess plateau area are more complex.

关 键 词：三维 复杂黄土塬区 复杂网格 初至波 走时计算 

分 类 号：P315[天文地球—地震学] P631[天文地球—固体地球物理学]