非规则三角网格有限差分法地震正演模拟
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摘要
针对有限差分方法在地震正演模拟中的广泛应用 ,提出了 1种基于三角形网格的地震正演模拟差分算法。相对于矩形网格差分法而言 ,该方法可以更为精确地描述弯曲的速度界面 ,可直接用于起伏地表模型的正演模拟计算而无需对模型做特殊处理。由于空间步长可随速度的变化而改变 ,加之在递推计算中采用了显式差分算法 ,该方法可视为对传统的规则网格有限差分法的有效改进。数值模拟的结果表明该方法是稳定、精确的且具有较高的计算效率
A finite-difference seismic modeling method based on triangular grids is presented. Compared with the conventional finite-difference schemes based on rectangular grids, curved velocity boundaries can be more accurately represented by using the new approach. Models with an irregular earth surface can be directly used for seismic modeling without special processing. As the space steps can be varied with velocities and the explicit finite-difference scheme is used for calculation, the method is an effective improvement over the conventional finite-difference methods. Numerical tests demonstrate that this new method is stable, efficient and sufficiently accurate.
A finite-difference seismic modeling method based on triangular grids is presented. Compared with the conventional finite-difference schemes based on rectangular grids, curved velocity boundaries can be more accurately represented by using the new approach. Models with an irregular earth surface can be directly used for seismic modeling without special processing. As the space steps can be varied with velocities and the explicit finite-difference scheme is used for calculation, the method is an effective improvement over the conventional finite-difference methods. Numerical tests demonstrate that this new method is stable, efficient and sufficiently accurate.
引文
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[2] JastramC ,TessemerE .Elasticmodelingonagridofverticallyvaryingspacing[J].GeophysProsp,1994,42:357370.
[3] WangY ,SchusterGT.FiniteDifferenceVariableGridSchemeforAcous ticandElasticWaveEquationModeling[C].[s.l.]:66thAnnInternatMtgSocofExplGeophys(ExpandedAbstracts),1996.674677.
[4] DongQ ,RectorJW .Bi domainModelingofBoreholeWavePropagation[C].[s.l.]:67thAnn.InternatMtgSocofExplGeophys(ExpandedAbstracts),1997.262265.
[5] OprsalI,ZahradnikJ.ElasticfiniteDifferencemethodforirregulargrids[J].Geophysics,1999,64:240250.
[6] TessmerE .Seismicfinite differencemodelingwithspatiallyvaryingtimesteps[J].Geophysics,2000,65:12901293.
[7] WangY .VariableGridSizeandTimeStepFiniteDifferenceMethodforSeismicForwardModelingandReverseTimeMigration[D].Utah:De partmentofGeologyandGeophysics,UniversityofUtah,2000.
[8] MuirF ,DellingerJ,EtgenJ,etal.Modelingelasticfieldsacrossirregu larboundaries[J].Geophysics,1992,57:11891193.
[9] ZengX ,WestGF .Reducingspuriousdiffractionsinelasticwavefieldcal culations[J].Geophysics,1996,61:14361439.
[10] 李荣华.广义差分法及其应用[J].吉林大学自然科学学报,1995,(1):1422.
[11] KeiswetterD ,BlackR ,SchmeissnerC .AprogramforseismicwavefieldmodelingusingfiniteDifferencetechniques[J].Computers&Geo sciences,1995,22:267286.
[12] AlfordRM ,KellyKR ,BooreDM .AccuracyoffiniteDifferencemodel ingoftheacousticwaveequation[J].Geophysics,1974,39:834842.
[13] WangX ,WalthamD .Thestable beamseismicmodelingmethod[J].GeophysProsp,1995,43:939961.
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