山前带地震勘探策略与成像处理方法
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摘要
山前带地震资料信噪比低和道间时差剧变是引起此类地区成像困难的主要原因。本文从宏观速度估计的角度,分析了山前带勘探中野外数据采集、资料低信噪比和道间时差剧变等因素与后续成像处理的关系,认为速度建模是山前带成像处理的关键问题,山前带地震数据采集要以有利于近地表浅层速度建模和中深层宏观速度估计为目标。为此,本文提出了一套以宏观速度建模为核心的成像处理流程。在该流程中首先利用基于叠前深度偏移(PSDM)的扫描速度分析方法得到初始宏观速度场;再利用非水平地表射线束PSDM技术高效生成深度域成像道集;最后进行角度道集层析速度估计,为射线束PSDM提供更精细速度模型。压噪和消除道间时差是该流程的两个关键环节。本文强调尽可能用同相叠加方法压制噪声,通过选取合适成像基准面以消除或减弱高波数道间时差对叠前成像的影响;中低波数道间时差由后续速度分析及成像消除,将静校正问题置于速度建模过程中加以解决。理论模型和实际资料成像结果验证了本文思路的正确性及方法的有效性。
The main challenges of pre-stack seismic data imaging in mountain areas are move-out differences among traces and low signal to noise ratio(SNR).Based on velocity estimation,this paper analyzes imaging problems with data acquisition,data low SNR and move-out differences in mountain areas.We find out that building an appropriate velocity model is the key of data imaging in mountain areas.A good velocity model is dependent on seismic data quality and seismic processing working flow.The acquisition geometry design should be benefit of velocity model building for shallow,middle and deep layers.An effective seismic data imaging procedure is presented on velocity estimation in mountain areas.Firstly,scanning velocity analysis is carried out to obtain an initial velocity model.Then,common image point gathers(CIGs)is generated by Beam-Ray Kirchhoff PSDM.Finally,the velocity model is iteratively updated by velocity tomography based on CIGs until obtain a satisfied velocity model.Noise suppression and move-out deduction among traces are also very important.We achieve these two tasks by in-phase stacking and suitable imaging datum choosing to remove high wave number move-out.The low wave number move-out will be deducted during PSDM procedure.In other words,the traditional statics is replaced by PSDM and migration velocity analysis(MVA).Both synthetic and field data examples demonstrate that the procedure is quite effective.
The main challenges of pre-stack seismic data imaging in mountain areas are move-out differences among traces and low signal to noise ratio(SNR).Based on velocity estimation,this paper analyzes imaging problems with data acquisition,data low SNR and move-out differences in mountain areas.We find out that building an appropriate velocity model is the key of data imaging in mountain areas.A good velocity model is dependent on seismic data quality and seismic processing working flow.The acquisition geometry design should be benefit of velocity model building for shallow,middle and deep layers.An effective seismic data imaging procedure is presented on velocity estimation in mountain areas.Firstly,scanning velocity analysis is carried out to obtain an initial velocity model.Then,common image point gathers(CIGs)is generated by Beam-Ray Kirchhoff PSDM.Finally,the velocity model is iteratively updated by velocity tomography based on CIGs until obtain a satisfied velocity model.Noise suppression and move-out deduction among traces are also very important.We achieve these two tasks by in-phase stacking and suitable imaging datum choosing to remove high wave number move-out.The low wave number move-out will be deducted during PSDM procedure.In other words,the traditional statics is replaced by PSDM and migration velocity analysis(MVA).Both synthetic and field data examples demonstrate that the procedure is quite effective.
引文
[1]王卫华.速度横向变化对地震成像的影响.石油地球物理勘探,2007,42(6):720～726 Wang Weihua.Influence of lateral velocity variation on seismic imaging.OGP,2007,42(6):720～726
[2]Berryhill J.Wave-equation datuming before stack.Geophysics,1984,49(2):2064～2066
[3]Bevc D.Flooding the topography:Wave equation da-tuming of land data with rugged acquisition topogra-phy.Geophysics,1997,62(1):1586～1595
[4]Raiaskaran S and McMechan G A.Prestack process-ing of land data with complex topography.Geophy-sics,1995,60(6):1875～1886
[5]Wiggins J W.Kirchhoff integral extrapolation and migration of nonplanar data.Geophysics,1984,49(8):1239～1248
[6]Gray S H and Marfurt K J.Migration from topography:Improving the near-surface image.Canadian Journal of Exploration Geophysics,1995,31(1):18～24
[7]Lines L,Wu W J,Lu H X et al.Migration from to-pography:experience with an Alberta foothills data set.Canadian Journal of Exploration Geophysics,1996,32(1):24～30
[8]Alkhalifah T and Bagaini C.Cost-effective datuming in presence of rough topography and complex near-surface.SEG Technical Program Expanded Ab-stracts,2004,23:2024～2027
[9]Wang H Z,Li W B,Zhang Y Q et al.Beam ray gather stacking for attenuating non-coherent noises and PSTM from rugged topography.SEG Technical Program Expanded Abstracts,2007,26:2635～2639
[10]Liu S Y and Wang H Z.An effective3D Kirchhoff PSDM and MVA procedure from rugged topography.EAGE Technical Program Expanded Abstracts,2011,No378
[11]Pratt R G,Shin C and Hicks G J.Gauss-Newton and full Newton methods in frequency-space seismic waveform inversion.Geophys J Int,1998,133(2):341～362
[12]Shin C and Cha Y H.Waveform inversion in the La-place-Fourier domain.Geophys J Int,2009,177(3):1067～1079
[13]杨金华,刘洋,满益志等.复杂构造区t0时间漂移和叠加速度特征分析及校正.石油地球物理勘探,2008,43(1):76～82 Yang Jinhua,Liu Yang,Man Yizhi et al.Analysis on t0time drift and character of stack velocity in area of complex structure and correction.OGP,2008,43(1):76～82
[14]Mosegaard K and Tarantola A.Monte Carlo analysis of geophysical inverse problems.SEG Technical Pro-gram Expanded Abstracts,1991,10:940
[15]Pramik B.Broadband land acquisition-survey design issues.SEG Technical Program Expanded Ab-stracts,2011,30:4344～4348
[16]王海,赵会欣,晋志刚.观测系统对高密度地震采集资料的影响.石油地球物理勘探,2009,42(2):131～135 Wang Hai,Zhao Huixin and Jin Zhigang.Influence of geometry on high-density seismic data acquisition.OGP,2009,42(2):131～135
[17]王永奎,殷全增,李攀峰.地震弯线技术在地形复杂地区煤田勘探中的应用.中国煤炭地质,2010,22(5):59～62 Wang Y K,Yin Q Z,Li P F.Application of seismic slalom line technology in complicated area coalfield prospecting.Coal Geology of China,2010,22(5):59～62
[18]杨庆道,王伟锋,尹以东等.弯线地震勘探技术应用中的若干问题.石油地球物理勘探,2011,46(3):364～369 Yang Qingdao,Wang Weifang,Yin Yidong et al.Some issues in applications of seismic crooked line.OGP,2011,46(3):364～369
[19]Milton A,Trickett S and Burroughs L.Reducing ac-quisition costs with random sampling and multidimen-sional interpolation.SEG Technical Program Ex-panded Abstracts,2011,30:52～56
[20]陈学强,白文杰,钟海.沙漠区高信噪比地震采集方法.石油地球物理勘探,2010,45(3):321～325 Chen Xueqiang,Bai Wenjie and Zhang Hai.High signal-to-noise ratio seismic acquisition methods in desert area.OGP,2010,45(3):321～325
[21]Goertz A,Milligan P,Karrenbach M et al.Optimized 3DVSP survey geometry based on Fresnel zone esti-mates.SEG Technical Program Expanded Ab-stracts,2005,24:2641～2644
[22]施继承,和冠慧,张中民等.巴基斯坦复杂地表区地震采集技术.石油地球物理勘探,2008,43(增刊2):11～14 Shi Jicheng,He Guanhui,Zhang Zhongmin et al.Seis-mic acquisition technology in Pakistan complicated surface area.OGP,2008,43(Sup2):11～14
[23]陈学强,张林.复杂地表条件下的变观设计技术.石油地球物理勘探,2007,42(5):495～498 Chen Xueqiang and Zhang Lin.Geometry-variable de-sign in complex surface conditions.OGP,2007,42(5):495～498
[24]杨勤勇,常鉴,徐国庆.灰岩裸露区地震激发机理研究.石油地球物理勘探,2009,44(4):399～405 Yang Qinyong,Chang Jian,Xu Guoqing.Study on shooting mechanism of seismic waves in limestone-ex-posed area.OGP,2009,44(4):399～405
[25]石战结,田钢.西部大沙漠区近地表地震波衰减及高频补偿技术研究.石油地球物理勘探,2007,42(4):392～395 Shi Zhanjie and Tian Gang.Technique of attenuation of near-surface seismic wave and high-frequency com-pensation in western larg desert area.OGP,2007,42(4):392～395
[26]王华忠,程玖兵,马在田.地震波场深度外推消除与地面有关的噪声.同济大学学报,2000,28(3):333～336 Wang Huazhong,Cheng Jiubing and Ma Zaitian.Fil-tering noise related to land surface through depth ex-trapolation of seismic wave field.Journal of Tongji University,2000,28(3):333～336
[27]Hu J T,Wang X W,Wang H Z.Beam forming by least square inversion with radon spectrum con-straints.SEG Technical Program Expanded Ab-stracts,2012,31,http:∥dx.doi.org/10.1190/segam 2012-1140.1
[28]Hill R N.Prestack Gaussian-beam depth migration.Geophysics,2001,66(4):1240～1250
[29]Ting C Oand,Wang D L.Controlled beam migration applications in Gulf of Mexico.SEG Technical Pro-gram Expanded Abstracts,2008,27:368～372
[30]刘洪,刘国锋,李博等.基于横向导数的走时计算方法及其叠前时间偏移应用.石油物探,2009,48(1):3～10 Liu Hong,Liu Guofeng,Li Bo et al.The travel time calculation method via laterally derivative to velocity and its application in prestack time migration.geo-physical prospecting for petroleum.GPP,2009,48(1):3～10
[31]Li J C,Pham D.Land data migration from rugged to-pography.SEG Technical Program Expanded Ab-stracts,2002,21:1137～1139
[2]Berryhill J.Wave-equation datuming before stack.Geophysics,1984,49(2):2064～2066
[3]Bevc D.Flooding the topography:Wave equation da-tuming of land data with rugged acquisition topogra-phy.Geophysics,1997,62(1):1586～1595
[4]Raiaskaran S and McMechan G A.Prestack process-ing of land data with complex topography.Geophy-sics,1995,60(6):1875～1886
[5]Wiggins J W.Kirchhoff integral extrapolation and migration of nonplanar data.Geophysics,1984,49(8):1239～1248
[6]Gray S H and Marfurt K J.Migration from topography:Improving the near-surface image.Canadian Journal of Exploration Geophysics,1995,31(1):18～24
[7]Lines L,Wu W J,Lu H X et al.Migration from to-pography:experience with an Alberta foothills data set.Canadian Journal of Exploration Geophysics,1996,32(1):24～30
[8]Alkhalifah T and Bagaini C.Cost-effective datuming in presence of rough topography and complex near-surface.SEG Technical Program Expanded Ab-stracts,2004,23:2024～2027
[9]Wang H Z,Li W B,Zhang Y Q et al.Beam ray gather stacking for attenuating non-coherent noises and PSTM from rugged topography.SEG Technical Program Expanded Abstracts,2007,26:2635～2639
[10]Liu S Y and Wang H Z.An effective3D Kirchhoff PSDM and MVA procedure from rugged topography.EAGE Technical Program Expanded Abstracts,2011,No378
[11]Pratt R G,Shin C and Hicks G J.Gauss-Newton and full Newton methods in frequency-space seismic waveform inversion.Geophys J Int,1998,133(2):341～362
[12]Shin C and Cha Y H.Waveform inversion in the La-place-Fourier domain.Geophys J Int,2009,177(3):1067～1079
[13]杨金华,刘洋,满益志等.复杂构造区t0时间漂移和叠加速度特征分析及校正.石油地球物理勘探,2008,43(1):76～82 Yang Jinhua,Liu Yang,Man Yizhi et al.Analysis on t0time drift and character of stack velocity in area of complex structure and correction.OGP,2008,43(1):76～82
[14]Mosegaard K and Tarantola A.Monte Carlo analysis of geophysical inverse problems.SEG Technical Pro-gram Expanded Abstracts,1991,10:940
[15]Pramik B.Broadband land acquisition-survey design issues.SEG Technical Program Expanded Ab-stracts,2011,30:4344～4348
[16]王海,赵会欣,晋志刚.观测系统对高密度地震采集资料的影响.石油地球物理勘探,2009,42(2):131～135 Wang Hai,Zhao Huixin and Jin Zhigang.Influence of geometry on high-density seismic data acquisition.OGP,2009,42(2):131～135
[17]王永奎,殷全增,李攀峰.地震弯线技术在地形复杂地区煤田勘探中的应用.中国煤炭地质,2010,22(5):59～62 Wang Y K,Yin Q Z,Li P F.Application of seismic slalom line technology in complicated area coalfield prospecting.Coal Geology of China,2010,22(5):59～62
[18]杨庆道,王伟锋,尹以东等.弯线地震勘探技术应用中的若干问题.石油地球物理勘探,2011,46(3):364～369 Yang Qingdao,Wang Weifang,Yin Yidong et al.Some issues in applications of seismic crooked line.OGP,2011,46(3):364～369
[19]Milton A,Trickett S and Burroughs L.Reducing ac-quisition costs with random sampling and multidimen-sional interpolation.SEG Technical Program Ex-panded Abstracts,2011,30:52～56
[20]陈学强,白文杰,钟海.沙漠区高信噪比地震采集方法.石油地球物理勘探,2010,45(3):321～325 Chen Xueqiang,Bai Wenjie and Zhang Hai.High signal-to-noise ratio seismic acquisition methods in desert area.OGP,2010,45(3):321～325
[21]Goertz A,Milligan P,Karrenbach M et al.Optimized 3DVSP survey geometry based on Fresnel zone esti-mates.SEG Technical Program Expanded Ab-stracts,2005,24:2641～2644
[22]施继承,和冠慧,张中民等.巴基斯坦复杂地表区地震采集技术.石油地球物理勘探,2008,43(增刊2):11～14 Shi Jicheng,He Guanhui,Zhang Zhongmin et al.Seis-mic acquisition technology in Pakistan complicated surface area.OGP,2008,43(Sup2):11～14
[23]陈学强,张林.复杂地表条件下的变观设计技术.石油地球物理勘探,2007,42(5):495～498 Chen Xueqiang and Zhang Lin.Geometry-variable de-sign in complex surface conditions.OGP,2007,42(5):495～498
[24]杨勤勇,常鉴,徐国庆.灰岩裸露区地震激发机理研究.石油地球物理勘探,2009,44(4):399～405 Yang Qinyong,Chang Jian,Xu Guoqing.Study on shooting mechanism of seismic waves in limestone-ex-posed area.OGP,2009,44(4):399～405
[25]石战结,田钢.西部大沙漠区近地表地震波衰减及高频补偿技术研究.石油地球物理勘探,2007,42(4):392～395 Shi Zhanjie and Tian Gang.Technique of attenuation of near-surface seismic wave and high-frequency com-pensation in western larg desert area.OGP,2007,42(4):392～395
[26]王华忠,程玖兵,马在田.地震波场深度外推消除与地面有关的噪声.同济大学学报,2000,28(3):333～336 Wang Huazhong,Cheng Jiubing and Ma Zaitian.Fil-tering noise related to land surface through depth ex-trapolation of seismic wave field.Journal of Tongji University,2000,28(3):333～336
[27]Hu J T,Wang X W,Wang H Z.Beam forming by least square inversion with radon spectrum con-straints.SEG Technical Program Expanded Ab-stracts,2012,31,http:∥dx.doi.org/10.1190/segam 2012-1140.1
[28]Hill R N.Prestack Gaussian-beam depth migration.Geophysics,2001,66(4):1240～1250
[29]Ting C Oand,Wang D L.Controlled beam migration applications in Gulf of Mexico.SEG Technical Pro-gram Expanded Abstracts,2008,27:368～372
[30]刘洪,刘国锋,李博等.基于横向导数的走时计算方法及其叠前时间偏移应用.石油物探,2009,48(1):3～10 Liu Hong,Liu Guofeng,Li Bo et al.The travel time calculation method via laterally derivative to velocity and its application in prestack time migration.geo-physical prospecting for petroleum.GPP,2009,48(1):3～10
[31]Li J C,Pham D.Land data migration from rugged to-pography.SEG Technical Program Expanded Ab-stracts,2002,21:1137～1139
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