界面二次源波前扩展法全局最小走时射线追踪技术
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摘要
以Moser方法为代表的最短路径射线追踪算法可以快速稳定地获得整个追踪区域的全局最小走时和路径,但它存在两个缺陷:一是射线大多由折线呈锯齿状相连,长度和位置偏离真实射线路径;二是在低变速区容易出现射线路径多值现象.本文提出的界面二次源波前扩展法全局最小走时射线追踪技术(以下简称界面源法)旨在解决上述两个问题.不同于Moser方法,界面源法只在物性分界面上设置子波源点,子波出射射线可以到达任何不穿越物性界面而直接到达的空间点和界面离散点,在均匀块体内或层内地震波以精确的射线路径传播.显然,界面源法的子波出射方向数远远大于传统方法,算法的追踪误差主要由界面离散引起的,因此,界面源法很好地解决了Moser法存在的问题,大大提高了追踪的精度.同时,由于界面源法的子波源点数远远小于Moser法,因而效率也很高.模型实算证实了该算法的高效性.
The shortest path raytracing presented by Moser is a kind of fast and stable method to calculate global minimum traveltimes and raypaths.But it has two drawbacks.One is that most derived zig-zag raypaths are longer than true paths and thus mispozitioned.The other is that there may be several equally short paths,especially in flat areas with low velocity variations.The wavefront expanding method with interface points as secondary sources is studied in the paper which aims to solve the problems.Different from Moser's method,this approach only sets secondary sources on interfaces between different media.Rays from a secondary source can reach nodes as long as paths don't penetrate interfaces.Waves propagate along accurate paths in homogeneous layers or blocks.Obviously,there are much more ray directions from a secondary source with this method than with Moser's method.The main tracing errors only come from interface discretization.As a result,raytracing with the method can get much more accurate results than Moser's method.At the same time,the method is efficient as there are much less secondary sources than those in Moser's.Numerical examples show the method is efficient.
The shortest path raytracing presented by Moser is a kind of fast and stable method to calculate global minimum traveltimes and raypaths.But it has two drawbacks.One is that most derived zig-zag raypaths are longer than true paths and thus mispozitioned.The other is that there may be several equally short paths,especially in flat areas with low velocity variations.The wavefront expanding method with interface points as secondary sources is studied in the paper which aims to solve the problems.Different from Moser's method,this approach only sets secondary sources on interfaces between different media.Rays from a secondary source can reach nodes as long as paths don't penetrate interfaces.Waves propagate along accurate paths in homogeneous layers or blocks.Obviously,there are much more ray directions from a secondary source with this method than with Moser's method.The main tracing errors only come from interface discretization.As a result,raytracing with the method can get much more accurate results than Moser's method.At the same time,the method is efficient as there are much less secondary sources than those in Moser's.Numerical examples show the method is efficient.
引文
[1]Julian B R,Gubbins D.Three-dimensional seismic ray tracing.J.Geophys.,1977,43(1):95~114
[2]Thurber C H,Ellsworth W L.Rapid solution of ray tracing problemsin heterogeneous media.Bull.Seis.Soc.Am.,1980,70(4):1137~1148
[3]高亮,李幼铭,陈旭荣等.地震射线辛几何算法初探.地球物理学报,2000,43(3):402~410Gao L,Li Y M,Chen X R,et al.An attempt to seismic ray tracingwith Symplectic algorithm.Chinese J.Geophys.(in Chinese),2000,43(3):402~410
[4]秦孟兆,陈景波.Maslov渐近理论与辛几何算法.地球物理学报,2000,43(4):522~533Qin M Z,Chen J B.Maslov asymptotic theory and Symplecticalgorithm.Chinese J.Geophys.(in Chinese),2000,43(4):522~533
[5]陈景波,秦孟兆.射线追踪、辛几何算法与波场的数值模拟.计算物理,2001,18(6):481~487Chen J B,Qin M Z.Ray tracing,Symplectic algorithm and wavefield simulation.Chinese J.Comput.Phys.(in Chinese),2001,18(6):481~487
[6]Nakanishi I,Yamaguchi K.A numerical experiment on nonlinearimage reconstruction from first arrival times for two dimensional islandarc structure.J.Phys.Earth,1986,34(1):195~201
[7]Moser T J.Shortest path calculation of seismic rays.Geophysics,1991,56(1):59~67
[8]Fisher R,Lees,J M.Shortest path ray tracing with sparse graphs.Geophysics,1993,58(7):987~996
[9]Klime L,Kvasni?ka M.3-D network ray tracing.Geophys.J.Int.,1994,116(3):726~738
[10]Zhang J,Toksoz M N.Nonlinear refraction traveltime tomography.Geophysics,1998.63(6):1726~1737
[11]Van Avendonk H J A,Harding A J,Orcutt J A,et al.Hybridshortest path and ray bending method for traveltime and raypathcalculations.Geophysics,2001,66(2):648~653
[12]王辉,常旭.基于图形结构的三维射线追踪方法.地球物理学报,2000,43(4):534~541Wang H,Chang X.3-D ray tracing method based on graphicstructure.Chinese J.Geophys.(in Chinese),2000,43(4):534~541
[13]赵爱华,张中杰,王光杰等.非均匀介质中地震波走时与射线路径快速计算技术.地震学报,2000,22(1):151~157Zhao A H,Zhang Z J,Wang G J,et al.A new scheme for fastcalculation of seismic traveltimes and ray paths in heterogeneousmedia.Acta Seismol.Sin.(in Chinese),2000,22(1):151~157
[14]Zhao A,Zhang Z,Teng J.Minimum travel time tree algorithm forseismic ray tracing:improvement in efficiency.J.Geophys.Eng.,2004,1(2):245~251
[15]刘洪,孟凡林,李幼铭.计算最小走时和射线路径的界面网全局方法.地球物理学报,1995,38(6):823~832Liu H,Meng F L,Li Y M.The interface grid method for seekingglobal minimum travel-time and the correspondent raypath.ChineseJ.Geophys.(in Chinese),1995,38(6):823~832
[16]张建中,陈世军,余大祥.最短路径射线追踪方法及其改进.地球物理学进展,2003,18(1):146~150Zhang J Z,Chen S J,Yu D X.Improvement of shortest path raytracing method.Progress in Geophys.(in Chinese),2003,18(1):146~150
[17]张建中,陈世军,徐初伟.动态网络最短路径射线追踪.地球物理学报,2004,47(5):899~904Zhang J Z,Chen S J,Xu C W.A method of shortest path raytracingwith dynamic networks.Chinese J.Geophys.(in Chinese),2004,47(5):899~904
[18]何樵登,熊维纲.应用地球物理教程———地震勘探.北京:地质出版社,1991He Q D,Xiong W G.Applied Geophysics-Seismic Exploration(inChinese).Beijing:Geological Publishing House,1991
[2]Thurber C H,Ellsworth W L.Rapid solution of ray tracing problemsin heterogeneous media.Bull.Seis.Soc.Am.,1980,70(4):1137~1148
[3]高亮,李幼铭,陈旭荣等.地震射线辛几何算法初探.地球物理学报,2000,43(3):402~410Gao L,Li Y M,Chen X R,et al.An attempt to seismic ray tracingwith Symplectic algorithm.Chinese J.Geophys.(in Chinese),2000,43(3):402~410
[4]秦孟兆,陈景波.Maslov渐近理论与辛几何算法.地球物理学报,2000,43(4):522~533Qin M Z,Chen J B.Maslov asymptotic theory and Symplecticalgorithm.Chinese J.Geophys.(in Chinese),2000,43(4):522~533
[5]陈景波,秦孟兆.射线追踪、辛几何算法与波场的数值模拟.计算物理,2001,18(6):481~487Chen J B,Qin M Z.Ray tracing,Symplectic algorithm and wavefield simulation.Chinese J.Comput.Phys.(in Chinese),2001,18(6):481~487
[6]Nakanishi I,Yamaguchi K.A numerical experiment on nonlinearimage reconstruction from first arrival times for two dimensional islandarc structure.J.Phys.Earth,1986,34(1):195~201
[7]Moser T J.Shortest path calculation of seismic rays.Geophysics,1991,56(1):59~67
[8]Fisher R,Lees,J M.Shortest path ray tracing with sparse graphs.Geophysics,1993,58(7):987~996
[9]Klime L,Kvasni?ka M.3-D network ray tracing.Geophys.J.Int.,1994,116(3):726~738
[10]Zhang J,Toksoz M N.Nonlinear refraction traveltime tomography.Geophysics,1998.63(6):1726~1737
[11]Van Avendonk H J A,Harding A J,Orcutt J A,et al.Hybridshortest path and ray bending method for traveltime and raypathcalculations.Geophysics,2001,66(2):648~653
[12]王辉,常旭.基于图形结构的三维射线追踪方法.地球物理学报,2000,43(4):534~541Wang H,Chang X.3-D ray tracing method based on graphicstructure.Chinese J.Geophys.(in Chinese),2000,43(4):534~541
[13]赵爱华,张中杰,王光杰等.非均匀介质中地震波走时与射线路径快速计算技术.地震学报,2000,22(1):151~157Zhao A H,Zhang Z J,Wang G J,et al.A new scheme for fastcalculation of seismic traveltimes and ray paths in heterogeneousmedia.Acta Seismol.Sin.(in Chinese),2000,22(1):151~157
[14]Zhao A,Zhang Z,Teng J.Minimum travel time tree algorithm forseismic ray tracing:improvement in efficiency.J.Geophys.Eng.,2004,1(2):245~251
[15]刘洪,孟凡林,李幼铭.计算最小走时和射线路径的界面网全局方法.地球物理学报,1995,38(6):823~832Liu H,Meng F L,Li Y M.The interface grid method for seekingglobal minimum travel-time and the correspondent raypath.ChineseJ.Geophys.(in Chinese),1995,38(6):823~832
[16]张建中,陈世军,余大祥.最短路径射线追踪方法及其改进.地球物理学进展,2003,18(1):146~150Zhang J Z,Chen S J,Yu D X.Improvement of shortest path raytracing method.Progress in Geophys.(in Chinese),2003,18(1):146~150
[17]张建中,陈世军,徐初伟.动态网络最短路径射线追踪.地球物理学报,2004,47(5):899~904Zhang J Z,Chen S J,Xu C W.A method of shortest path raytracingwith dynamic networks.Chinese J.Geophys.(in Chinese),2004,47(5):899~904
[18]何樵登,熊维纲.应用地球物理教程———地震勘探.北京:地质出版社,1991He Q D,Xiong W G.Applied Geophysics-Seismic Exploration(inChinese).Beijing:Geological Publishing House,1991
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