非零偏VSP弹性波叠前逆时深度偏移技术探讨
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摘要
非零偏VSP地震资料是一种多分量资料,处理非零偏VSP资料,弹性波叠前逆时深度偏移技术无疑是最适合的处理技术.本文从二维各向同性介质的弹性波波动方程出发,研究了对非零偏VSP资料进行叠前逆时深度偏移的偏移算法,讨论了逆时传播过程中的边值问题和数值频散问题及其相应的解决方案;采用求解程函方程计算得到地下各点的地震波初至时间作为成像时间,实现了非零偏VSP资料的叠前逆时深度偏移.最后进行了模型试算和非零偏VSP地震资料的试处理,结果表明该方法不受地层倾角限制,较适用于高陡构造地区或介质横向速度变化较大地区的非零偏VSP地震资料处理.
Offset VSP seismic data is a kind of multicomponent data,the elastic prestack reverse-time depth migration technology is no doubt the best suitable for processing offset VSP data.This paper studied prestack reverse-time depth migration algorithms based on elastic wave equation in 2D isotropic media for offset VSP data,and discussed the boundary value problems and frequency dispersion problems and their relevant solution in wavefield reverse-time propagation,then used the solution of eikonal equation to get the one-way traveltime from the source to each point in the image space,which is regarded as the image time at that point,and complemented the prestack reverse-time depth migration for offset VSP data.Finally,we carried out model test and processed offset VSP data.The processing results proved that the scheme is not influenced by lay inclination and suited to process offset VSP data from the areas with steep subsurface structures and big variation of horizontal velocities.
Offset VSP seismic data is a kind of multicomponent data,the elastic prestack reverse-time depth migration technology is no doubt the best suitable for processing offset VSP data.This paper studied prestack reverse-time depth migration algorithms based on elastic wave equation in 2D isotropic media for offset VSP data,and discussed the boundary value problems and frequency dispersion problems and their relevant solution in wavefield reverse-time propagation,then used the solution of eikonal equation to get the one-way traveltime from the source to each point in the image space,which is regarded as the image time at that point,and complemented the prestack reverse-time depth migration for offset VSP data.Finally,we carried out model test and processed offset VSP data.The processing results proved that the scheme is not influenced by lay inclination and suited to process offset VSP data from the areas with steep subsurface structures and big variation of horizontal velocities.
引文
[1]Kuo J T,Dai T F.Kirchholf elastic wave migration for thecase of noncoincident source and receiver.Geophysics,1984,49:1223-1238.
[2]Dai T F,and Kuo J T.Real data results of Kirchholf elasticwave migration.Geophysics,1986,51:1006-1011.
[3]Sun R,McMechan G A.Prestack reverse-time migration forelastic waves with application to synthetic offset verticalseismic profiles.Proc.IEEE,1986,74:457-465.
[4]Chang W F,McMechan G A.Elastic reverse-time migration.Geophysics,1987,52:1365-1375.
[5]Chang W F,McMechan G A.3Delastic prestack reverse-timedepth migration.Geophysics,1994,59:597-609.
[6]Sun R,McMechan G A.Scalar reverse-time depth migrationof prestack elastic seismic data.Geophysics,2001,66:1519-1527.
[7]秦福浩.弹性波克希霍夫积分偏移法.地球物理学报,1988,31(5):56-78.Qin F H.Prestack Kirchhoff integral migration of elasticwave.Chinese J.Geophys.(in Chinese),1988,31(5):56-78.
[8]张关泉,周洪波.地面记录的纵横波分离.石油地球物理勘探,1995,30(2):181-191.Zhang G Q,Zhou H B.Separating compressional wave fromshear wave in Surface seismic records.Oil GeophysicalProspecting(in Chinese),1995,30(2):181-191.
[9]魏修成,刘洋.高精度转换波速度分析.石油勘探与开发,2000,27(2):57-59.Liu Y,Wei X C.High precision velocity analysis ofconverted wave.Petroleum Exploraton and Development(inChinese),2000,27(2):57-59.
[10]刘洋,魏修成.转换波三参数速度分析及动校正方法,石油地球物理勘探,2005,40(5):504-509.Liu Y,Wei X C.Three-parameter velocity analysis ofconverted wave and NMO method.Oil Geophysical Prospecting(in Chinese),2005,40(5):504-509.
[11]李文杰,魏修成,宁俊瑞等.叠前弹性波逆时深度偏移及波场分离技术探讨,物探化探计算技术,2008,30(6):447-456.Li W J,Wei X C,Ning J R,et al.The discussion of reversetime depth migration and wavefield separ-ation for prestackelastic data.Computing Techniques for Geophysical andGeochemical Exploration(in Chinese),2008,30(6):447-456.
[12]李文杰,魏修成,宁俊瑞等.弹性波叠前逆时深度偏移技术及其应用,中国石油大学学报(自然科学版),2009,33(4):52-58.Li W J,Wei X C,Ning J R,et al.Reverse-time depthmigration technology of prestack elastic wave-field and itsapplication.Journal of China University of Petroleum(Edition of Natural Science)(in Chinese),2009,33(4):52-58.
[13]Kelly K R,Ward R W,Sven Treitel,et al.Syntheticseismograms:a finite difference approach.Geophysics,1976,41(1):2-27.
[14]李文杰,魏修成,宁俊瑞.一种新的弹性波数值模拟吸收边界条件,石油地球物理勘探,2009,44(4):501-507.Li W J,Wei X C,Ning J R.A new numeric simulatingabsorbing boundary condition of elastic wave.Oil GeophysicalProspecting(in Chinese),2009,44(4):501-507.
[15]Boris J P,Book D L.Flux-corrected transport.I.SHASTA:A fluid transport algorithm that works.Comput.Phys,1973,11:38-69.
[16]Book D l,Boris J p,Hain K.Flux-corrected transport.II:generalization of the method.Comput.Phys,1975,18:248-283.
[17]杨顶辉,滕吉文.各向异性介质中三分量地震记录的FCT有限差分模拟.石油地球物理勘探,1997,32(2):181-190.Yang D H,Teng J W.FCT finite difference modeling ofthree-component seismic records in anisotropic medium.OilGeophysical Prospecting(in Chinese),1997,32(2):181-190.
[18]李文杰,张改兰,姜大建.利用FCT方法压制弹性数值模拟中的数值频散.物探化探计算技术,2011,33(3):248-251.Li W J,Zhang G L,Jiang D J.Suppressing numericaldispersion in finite difference modeling based on acoustic andelastic equation.Computing Techniques for Geophysical andGeochemical Exploration(in Chinese),2011,33(3):248-251.
[19]McMechan G A.Migration by extrapolation of time-dependent boundary values.Geophysical Prospecting,1983,31(2):413-420.
[20]Steve T,Hildebrand.Reverse-time depth migration:Impedanceimaging condition.Geophysics,1987,52(8):1060-1064.
[21]Claerbout J F.Toward a unified theory of reflector mapping.Geophysics,1971,36(2):467-481.
[22]张霖斌,刘迎曦.有限差分法射线追踪,石油地球物理勘探,1994,29(5):673-677.Zhang L B,Liu Y X.Ray tracing of finite difference method.Oil Geophysical Prospecting(in Chinese),1994,29(5):673-677.
[23]John Vidale.Finite difference calculation of travel times.Bull.Seis.Soc.Am.,1988,78(6):2062-2076.
[24]Fuhao Qin,Yi Luo,Kim B.Finite-difference solution of theeikonal equation along expanding wavefronts.Geophysics,1992,57(3):478-487.
[25]刘洪,孟繁林,李幼铭.计算最少走时和射线路径的界面网全局方法.地球物理学报,1995,38(6):823-831.Liu H,Meng F L,Li Y M.The interface grid method forseeking global minimum travel-time and the correspondentraypath.Chinese J.Geophys.(in Chinese),1995,38(6):823-831.
[26]李文杰,魏修成,宁俊瑞等.一种改进的利用程函方程计算旅行时的方法.石油地球物理勘探,2008,43(5):589-594.Li W J,Wei X C,Ning J R,et al.A method using improvedeikonal equation to computer travel time.Oil GeophysicalProspecting(in Chinese),2008,43(5):589-594.
[2]Dai T F,and Kuo J T.Real data results of Kirchholf elasticwave migration.Geophysics,1986,51:1006-1011.
[3]Sun R,McMechan G A.Prestack reverse-time migration forelastic waves with application to synthetic offset verticalseismic profiles.Proc.IEEE,1986,74:457-465.
[4]Chang W F,McMechan G A.Elastic reverse-time migration.Geophysics,1987,52:1365-1375.
[5]Chang W F,McMechan G A.3Delastic prestack reverse-timedepth migration.Geophysics,1994,59:597-609.
[6]Sun R,McMechan G A.Scalar reverse-time depth migrationof prestack elastic seismic data.Geophysics,2001,66:1519-1527.
[7]秦福浩.弹性波克希霍夫积分偏移法.地球物理学报,1988,31(5):56-78.Qin F H.Prestack Kirchhoff integral migration of elasticwave.Chinese J.Geophys.(in Chinese),1988,31(5):56-78.
[8]张关泉,周洪波.地面记录的纵横波分离.石油地球物理勘探,1995,30(2):181-191.Zhang G Q,Zhou H B.Separating compressional wave fromshear wave in Surface seismic records.Oil GeophysicalProspecting(in Chinese),1995,30(2):181-191.
[9]魏修成,刘洋.高精度转换波速度分析.石油勘探与开发,2000,27(2):57-59.Liu Y,Wei X C.High precision velocity analysis ofconverted wave.Petroleum Exploraton and Development(inChinese),2000,27(2):57-59.
[10]刘洋,魏修成.转换波三参数速度分析及动校正方法,石油地球物理勘探,2005,40(5):504-509.Liu Y,Wei X C.Three-parameter velocity analysis ofconverted wave and NMO method.Oil Geophysical Prospecting(in Chinese),2005,40(5):504-509.
[11]李文杰,魏修成,宁俊瑞等.叠前弹性波逆时深度偏移及波场分离技术探讨,物探化探计算技术,2008,30(6):447-456.Li W J,Wei X C,Ning J R,et al.The discussion of reversetime depth migration and wavefield separ-ation for prestackelastic data.Computing Techniques for Geophysical andGeochemical Exploration(in Chinese),2008,30(6):447-456.
[12]李文杰,魏修成,宁俊瑞等.弹性波叠前逆时深度偏移技术及其应用,中国石油大学学报(自然科学版),2009,33(4):52-58.Li W J,Wei X C,Ning J R,et al.Reverse-time depthmigration technology of prestack elastic wave-field and itsapplication.Journal of China University of Petroleum(Edition of Natural Science)(in Chinese),2009,33(4):52-58.
[13]Kelly K R,Ward R W,Sven Treitel,et al.Syntheticseismograms:a finite difference approach.Geophysics,1976,41(1):2-27.
[14]李文杰,魏修成,宁俊瑞.一种新的弹性波数值模拟吸收边界条件,石油地球物理勘探,2009,44(4):501-507.Li W J,Wei X C,Ning J R.A new numeric simulatingabsorbing boundary condition of elastic wave.Oil GeophysicalProspecting(in Chinese),2009,44(4):501-507.
[15]Boris J P,Book D L.Flux-corrected transport.I.SHASTA:A fluid transport algorithm that works.Comput.Phys,1973,11:38-69.
[16]Book D l,Boris J p,Hain K.Flux-corrected transport.II:generalization of the method.Comput.Phys,1975,18:248-283.
[17]杨顶辉,滕吉文.各向异性介质中三分量地震记录的FCT有限差分模拟.石油地球物理勘探,1997,32(2):181-190.Yang D H,Teng J W.FCT finite difference modeling ofthree-component seismic records in anisotropic medium.OilGeophysical Prospecting(in Chinese),1997,32(2):181-190.
[18]李文杰,张改兰,姜大建.利用FCT方法压制弹性数值模拟中的数值频散.物探化探计算技术,2011,33(3):248-251.Li W J,Zhang G L,Jiang D J.Suppressing numericaldispersion in finite difference modeling based on acoustic andelastic equation.Computing Techniques for Geophysical andGeochemical Exploration(in Chinese),2011,33(3):248-251.
[19]McMechan G A.Migration by extrapolation of time-dependent boundary values.Geophysical Prospecting,1983,31(2):413-420.
[20]Steve T,Hildebrand.Reverse-time depth migration:Impedanceimaging condition.Geophysics,1987,52(8):1060-1064.
[21]Claerbout J F.Toward a unified theory of reflector mapping.Geophysics,1971,36(2):467-481.
[22]张霖斌,刘迎曦.有限差分法射线追踪,石油地球物理勘探,1994,29(5):673-677.Zhang L B,Liu Y X.Ray tracing of finite difference method.Oil Geophysical Prospecting(in Chinese),1994,29(5):673-677.
[23]John Vidale.Finite difference calculation of travel times.Bull.Seis.Soc.Am.,1988,78(6):2062-2076.
[24]Fuhao Qin,Yi Luo,Kim B.Finite-difference solution of theeikonal equation along expanding wavefronts.Geophysics,1992,57(3):478-487.
[25]刘洪,孟繁林,李幼铭.计算最少走时和射线路径的界面网全局方法.地球物理学报,1995,38(6):823-831.Liu H,Meng F L,Li Y M.The interface grid method forseeking global minimum travel-time and the correspondentraypath.Chinese J.Geophys.(in Chinese),1995,38(6):823-831.
[26]李文杰,魏修成,宁俊瑞等.一种改进的利用程函方程计算旅行时的方法.石油地球物理勘探,2008,43(5):589-594.Li W J,Wei X C,Ning J R,et al.A method using improvedeikonal equation to computer travel time.Oil GeophysicalProspecting(in Chinese),2008,43(5):589-594.
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