叠前深度偏移技术的应用研究
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摘要
目前,常规的地震资料处理一般采用叠后时间偏移,但它只能解决反射层归位和绕射波收敛,而不能解决倾斜界面的非共反射点叠加问题。叠前偏移技术是解决精细速度分析和复杂构造成像的有效手段之一,也是近年来国内外地震资料成像的发展趋势。叠前深度偏移更是解决速度横向变化剧烈的复杂地区的地震资料成像的关键技术。
本文首先介绍了偏移的基本概念,以及其发展历史。根据偏移的这几个发展阶段,然后分别介绍了其基本原理和实现方法。
然后重点以酒泉盆地窟窿山逆掩推覆构造的一个三维工区为例,通过 GeoDepth 叠前深度偏移软件给出了三维叠前偏移的原理、实现步骤与成像效果。本次处理的任务要求查明窟窿山逆掩推覆带断层特征,要求断点清晰,目的层反射可靠,可对比追踪。根据资料特点,我们将处理过程分为时间域和深度域两个部分。本次资料时域处理的难点是:规则干扰的压制及随机干扰的衰减;叠前能量和频率的补偿;速度分析;静校正量的求取;正确的叠加成像,准确的偏移归位。根据原始资料的特点及处理的难点,以及地质任务处理要求和要解决的重点问题分析,本次处理采取了相应的技术措施。深度域处理的关键步骤是:(1)时间域构造模型的建立;(2)初始速度模型的建立;(3)速度模型的优化。通过时间剖面与深度偏移后剖面对比分析可以看出,深度偏移后的剖面较时间偏移剖面有一些改善,具体表现在以下几个方面:(1)深度偏移剖面构造形态相对完整,反射的信噪比有所提高;(2)经叠前深度偏移后,地层的接触关系清楚,(3)深浅层的成像都有一些的改进,波组特征较好,频带较宽,分辨率有一定的提高,振幅的保真度较高。不足之处一是由于叠前深度偏移的目标层较深,信噪比很低,成像效果不甚理想。二是偏移画弧现象在个别地方压制不够。
Normal seismic data processing usually uses post-stack migration ,however, it just canmake reflecting layers return its own position and make coiling wave converge and can't dealwith uncommon reflecting points stacking of inclining interfaces .The pre-stack migrationtechnique is one of the effective methods in solving fine velocity analysis and complexstructures imaging, at the same time it is also the development tendence of seismic dataimaging in our country or overseas in recent years. Pre-stack migration is also the keytechnique in solving seismic data imaging in complex areas where the velocity vary rapidly .
The paper firstly introduce the basic conception of migration and its developmenthistory .According to these development phases of migration ,it introduce the basic principleand achieving methods of migration.
The paper places the emphasis in the sample of a 3D prospect in Jiuquan basinKulongshan contradictory covering and overturning structure , through GeoDepth pre-stackmigration software introducing 3D pre-stack migration principle ,its achievement steps and itsimaging effect .The task require us to find out fault character of Kulongshan contradictorarycovering and overturning zoster and make broken points clearer and make objective layersmore reliable to be easily traced. According to data character ,we divide the process into timefield and depth field .The difficulty of data time process is : suppressing regular disturbanceand attenuating random disturbance;compensating pre-stack energy and frequency;velocityanalysis;calculating static correlations;right stacking and imaging ,accurate migration andreturn its position. According to the character of original data and the difficulty of theprocessing and the processing requirement of the geological task and the key things to bedealed with ,we adopt corresponding technique measurement. The key steps in depth field is :the first one is founding the structure model in time field;the second one is founding originalvelocity model;the third one is optimizing the velocity model. Comparing and analyzing thetime section with post-depth migration section, we can realize that there are someimprovement in depth migration section than time section and representing in these aspects:the first one is that the structure shape of depth migration is relatively integral and reflectingS/N improves;the second is that stratum contact relation is more clearer after pre-stack depthmigration;The third one is that there are also some improvement in imaging in deep andshallow stratum and that wave group character is preferable and that its frequency straps arewider and that the resolution improves and that swing fidelity is higher. The shortcoming isthat the imaging effect isn't perfect because the objective layer of pre-stack depth migration isvery deep and its S/N is very low. At the same time migration drawing arc phenomena can'tbe suppressed enough in some places.
本文首先介绍了偏移的基本概念,以及其发展历史。根据偏移的这几个发展阶段,然后分别介绍了其基本原理和实现方法。
然后重点以酒泉盆地窟窿山逆掩推覆构造的一个三维工区为例,通过 GeoDepth 叠前深度偏移软件给出了三维叠前偏移的原理、实现步骤与成像效果。本次处理的任务要求查明窟窿山逆掩推覆带断层特征,要求断点清晰,目的层反射可靠,可对比追踪。根据资料特点,我们将处理过程分为时间域和深度域两个部分。本次资料时域处理的难点是:规则干扰的压制及随机干扰的衰减;叠前能量和频率的补偿;速度分析;静校正量的求取;正确的叠加成像,准确的偏移归位。根据原始资料的特点及处理的难点,以及地质任务处理要求和要解决的重点问题分析,本次处理采取了相应的技术措施。深度域处理的关键步骤是:(1)时间域构造模型的建立;(2)初始速度模型的建立;(3)速度模型的优化。通过时间剖面与深度偏移后剖面对比分析可以看出,深度偏移后的剖面较时间偏移剖面有一些改善,具体表现在以下几个方面:(1)深度偏移剖面构造形态相对完整,反射的信噪比有所提高;(2)经叠前深度偏移后,地层的接触关系清楚,(3)深浅层的成像都有一些的改进,波组特征较好,频带较宽,分辨率有一定的提高,振幅的保真度较高。不足之处一是由于叠前深度偏移的目标层较深,信噪比很低,成像效果不甚理想。二是偏移画弧现象在个别地方压制不够。
Normal seismic data processing usually uses post-stack migration ,however, it just canmake reflecting layers return its own position and make coiling wave converge and can't dealwith uncommon reflecting points stacking of inclining interfaces .The pre-stack migrationtechnique is one of the effective methods in solving fine velocity analysis and complexstructures imaging, at the same time it is also the development tendence of seismic dataimaging in our country or overseas in recent years. Pre-stack migration is also the keytechnique in solving seismic data imaging in complex areas where the velocity vary rapidly .
The paper firstly introduce the basic conception of migration and its developmenthistory .According to these development phases of migration ,it introduce the basic principleand achieving methods of migration.
The paper places the emphasis in the sample of a 3D prospect in Jiuquan basinKulongshan contradictory covering and overturning structure , through GeoDepth pre-stackmigration software introducing 3D pre-stack migration principle ,its achievement steps and itsimaging effect .The task require us to find out fault character of Kulongshan contradictorarycovering and overturning zoster and make broken points clearer and make objective layersmore reliable to be easily traced. According to data character ,we divide the process into timefield and depth field .The difficulty of data time process is : suppressing regular disturbanceand attenuating random disturbance;compensating pre-stack energy and frequency;velocityanalysis;calculating static correlations;right stacking and imaging ,accurate migration andreturn its position. According to the character of original data and the difficulty of theprocessing and the processing requirement of the geological task and the key things to bedealed with ,we adopt corresponding technique measurement. The key steps in depth field is :the first one is founding the structure model in time field;the second one is founding originalvelocity model;the third one is optimizing the velocity model. Comparing and analyzing thetime section with post-depth migration section, we can realize that there are someimprovement in depth migration section than time section and representing in these aspects:the first one is that the structure shape of depth migration is relatively integral and reflectingS/N improves;the second is that stratum contact relation is more clearer after pre-stack depthmigration;The third one is that there are also some improvement in imaging in deep andshallow stratum and that wave group character is preferable and that its frequency straps arewider and that the resolution improves and that swing fidelity is higher. The shortcoming isthat the imaging effect isn't perfect because the objective layer of pre-stack depth migration isvery deep and its S/N is very low. At the same time migration drawing arc phenomena can'tbe suppressed enough in some places.
引文
[1] [美] 渥.伊尔马滋 著 黄绪德 袁明德 译《地震数据处理》 石油工业出版社
[2] Deregowski, S.M. 1990, Common-offset migration and velocity analysis, First Break, Vol.8, No.6, 225-234.
[3] 熊翥 《地震数据数字处理应用技术》 石油工业出版社
[4] R.E. 谢里夫 等 勘探地震学 石油工业出版社 1999
[5] Ristow D.,and Ruhl T.,Fourier finite-difference migration ,Geophysics,1994,59,1882-1893
[6] 牟永光 地震勘探资料数字处理方法 石油工业出版社 1981
[7] Advanced OMEGA SPS 1999
[8] Epos 3.0 GeoDepth 2D Tutorial (内部资料)
[9] 《沿层定点叠前深度偏移》 《地球物理勘探》 1997
[10] 赵政璋 王彦春 李庆忠等 编 《地震资料处理技术高级培训班教材》
[11] 杨长春等,地震叠前深度偏移方法流程及应用,地球物理学报,1996,39(4)
[12] 程佩青 数字信号处理教程 清华大学出版社 2001
[13] 陆孟基 地震勘探原理 石油工业出版社 2000
[14] 马在田 地震成像技术有限差分法偏移 石油工业出版社 1989
[15] 王华忠等 单平方根波场外推算子与波动方程叠前深度偏移 同济大学出版社 2000
[16] J.M.Carcione, An accurate and efficient scheme for wave propagation in linear viscoelastic media, Geophysics
[17] Gazdag J.,Modeling of the acoustic wave equation with transform methods,Geophysics 1981 46,854-859
[18] Seron F. J., Sanz F. J. and Kindelan M.,Elastic Wave propagation with the Finite-Element Method: Comparison of Different Numerical Techniques,SEG Annual meeting 1989,1283-1287
[19] Vafidis A.,Abramovic F.,and Kanasewich E.R.,Elastic wave propagation using fully vectorized high order finite-difference algorithms,Geophysics,1992,57,218-232
[20] Stolt R.,Migration by Fourier transform,Geophysics,1978,43,23-48
[21] 李庆忠 走向精确勘探的道路 石油工业出版社 1997
[22] Nielsen P., If F., Berg P. and Skovgarrd O., Using the pseudospectral technique on curved grids for 2D acoustic forward modelling: Geophysical Prospecting, 1994, 42, 321-341
[23] Kosloff D. D., and Baysal E., Forward model by a Fourier method: Geophysics, 1982, 47, 1402-1412
[24] Thompson J. F., Warsi Z. U. A. and Mastin C. W., Numerical Grid Generation- Foundations andApplication North Holland Publishing Co, 1985
[25] Berg P., If F. and Skovgaard A spectral method for seismic wave propagation in elastic media Wave Motion, 1990, 12, 415-427
[26] Nielsen P., If F., Berg P. and Skovgarrd O., Using the pseudospectral method on curved grids for 2D elastic forward modeling: Geophysical Prospecting, 1995, 43, 369-395
[27] Talezer H., Kosloff D. and Koren Z., An accurate scheme for seismic forward modeling: Geophysics Prespecting, 1987, 35, 479-490
[28]Stork,C.&Claytan,R,W.,An implementation of tomographic velocity analysis, Geophysics,vo1.56,no.2,1991,472-482
[29] Whitcombe,D,n.,Fast model building using demigration and single-step ray migration,Geophysics,vo1.59,no.2,1994,439-449
[30]P.R.Williomson, tomographic inversion in reflection seismology, Geophys.J.Int,Vol.100,1990,255-274
[31]ToruTakahashi,Prestack migration using arrival angle information, Geophysics, 1995,60(1):154-163
[32]Hale,D.,Stable explicit depth extrapolation of seismic wave fields, Geophysics, 1999,56(6):1770-1777
[33]Norman Bleistein,Jack cohen and Herman Jaramillo, true amplitude transformation to zero offset of data from curved reflectors, Geophysics, 1999,64(1):112-129
[34]Alexander Mihai Pouovici,Prestack migration by split-step DSR, Geophysics, 1996,vo1.61,no.5:1412-1416
[35]Jeroen C.M.Goudswaard,Fons P. Eten Kroode,Roel K. Snieder and Arie R.Verdel,detection of lateral velocity contrasts by crosswell traveltime tomography,Geophysics,1998,63(2):523-533
[36]Jin.S.,R.S.Wu, andC peng,1998, Prestack depth migation using a hybrid pseudo-screen propagator, 68 `h Ann. Internat. Mtg., Soc. Expl. Geophys., Expanded abstracts,p1819-1822
[37]Jin.S.,R.S.Wu, and peng, seismic depth migration with screen prpagators, Computational Geosciences, 1999,V613:321-355
[38]Mittet,R.,R.sollie, and K. Hokstad, Prestack depth migration with compensation for absorption and dispersion, Geophysics, 1995, Vo160:485 1494.
[39]Kessinger, WP.,1992,Extended spilt-step Fourier migration, 62th Ann. Internat. Mtg., Soc. Expl. Geophys., Expanded abstracts,p917-920
[40]Ristow,D., 3-D implicit finite-differernce migration by multiway splitting, Geophysics, 1997,62(2):554-567
[41]Ristow,D.,and T. ruhl, fourier finite-difference migration Geophysics, 1994, 59(12):1882-1893
[42]stoffa, P.L.,J.1fokkema, R.M.de luna Freire, and W.P. Kessinger, split-step Fourier migration, Geophysics, 1990,55(4):410-421
[43]Stolt, R,H., Migration by Fourier Transform, Geophysics, 1978,43(1):23-48
[44]Zhang Guanquan et al, A new algorithm for finite-difference of steep dips, Geophysics, 1998,Vol53:167-175
[45]Ruhl, Tand Ristow D, 1995,Fourier FD migration: the missing link between phase -shift and FD migration,65`h Annual SEG Mtg, p1232-1234
[46]Samuel H Gray ,et al .Seisimic migration problems and solutions. Geophysics,2001,66(5):1622-1640
[47]Baoniu Han. A comparison of four depth migration methods. 68`h SEG Annual Meeting, 1998 ,p49-76
[48]Gray S H, May W P. kirchhoff migration using eikonal equation travel times. Geophysics, 1994,59(2):810-817
[49]Gray S H,Frequency-selective design of Kirchhoff migration operator,Geophysical Prospecting, 1992,40(4):564-571
[2] Deregowski, S.M. 1990, Common-offset migration and velocity analysis, First Break, Vol.8, No.6, 225-234.
[3] 熊翥 《地震数据数字处理应用技术》 石油工业出版社
[4] R.E. 谢里夫 等 勘探地震学 石油工业出版社 1999
[5] Ristow D.,and Ruhl T.,Fourier finite-difference migration ,Geophysics,1994,59,1882-1893
[6] 牟永光 地震勘探资料数字处理方法 石油工业出版社 1981
[7] Advanced OMEGA SPS 1999
[8] Epos 3.0 GeoDepth 2D Tutorial (内部资料)
[9] 《沿层定点叠前深度偏移》 《地球物理勘探》 1997
[10] 赵政璋 王彦春 李庆忠等 编 《地震资料处理技术高级培训班教材》
[11] 杨长春等,地震叠前深度偏移方法流程及应用,地球物理学报,1996,39(4)
[12] 程佩青 数字信号处理教程 清华大学出版社 2001
[13] 陆孟基 地震勘探原理 石油工业出版社 2000
[14] 马在田 地震成像技术有限差分法偏移 石油工业出版社 1989
[15] 王华忠等 单平方根波场外推算子与波动方程叠前深度偏移 同济大学出版社 2000
[16] J.M.Carcione, An accurate and efficient scheme for wave propagation in linear viscoelastic media, Geophysics
[17] Gazdag J.,Modeling of the acoustic wave equation with transform methods,Geophysics 1981 46,854-859
[18] Seron F. J., Sanz F. J. and Kindelan M.,Elastic Wave propagation with the Finite-Element Method: Comparison of Different Numerical Techniques,SEG Annual meeting 1989,1283-1287
[19] Vafidis A.,Abramovic F.,and Kanasewich E.R.,Elastic wave propagation using fully vectorized high order finite-difference algorithms,Geophysics,1992,57,218-232
[20] Stolt R.,Migration by Fourier transform,Geophysics,1978,43,23-48
[21] 李庆忠 走向精确勘探的道路 石油工业出版社 1997
[22] Nielsen P., If F., Berg P. and Skovgarrd O., Using the pseudospectral technique on curved grids for 2D acoustic forward modelling: Geophysical Prospecting, 1994, 42, 321-341
[23] Kosloff D. D., and Baysal E., Forward model by a Fourier method: Geophysics, 1982, 47, 1402-1412
[24] Thompson J. F., Warsi Z. U. A. and Mastin C. W., Numerical Grid Generation- Foundations andApplication North Holland Publishing Co, 1985
[25] Berg P., If F. and Skovgaard A spectral method for seismic wave propagation in elastic media Wave Motion, 1990, 12, 415-427
[26] Nielsen P., If F., Berg P. and Skovgarrd O., Using the pseudospectral method on curved grids for 2D elastic forward modeling: Geophysical Prospecting, 1995, 43, 369-395
[27] Talezer H., Kosloff D. and Koren Z., An accurate scheme for seismic forward modeling: Geophysics Prespecting, 1987, 35, 479-490
[28]Stork,C.&Claytan,R,W.,An implementation of tomographic velocity analysis, Geophysics,vo1.56,no.2,1991,472-482
[29] Whitcombe,D,n.,Fast model building using demigration and single-step ray migration,Geophysics,vo1.59,no.2,1994,439-449
[30]P.R.Williomson, tomographic inversion in reflection seismology, Geophys.J.Int,Vol.100,1990,255-274
[31]ToruTakahashi,Prestack migration using arrival angle information, Geophysics, 1995,60(1):154-163
[32]Hale,D.,Stable explicit depth extrapolation of seismic wave fields, Geophysics, 1999,56(6):1770-1777
[33]Norman Bleistein,Jack cohen and Herman Jaramillo, true amplitude transformation to zero offset of data from curved reflectors, Geophysics, 1999,64(1):112-129
[34]Alexander Mihai Pouovici,Prestack migration by split-step DSR, Geophysics, 1996,vo1.61,no.5:1412-1416
[35]Jeroen C.M.Goudswaard,Fons P. Eten Kroode,Roel K. Snieder and Arie R.Verdel,detection of lateral velocity contrasts by crosswell traveltime tomography,Geophysics,1998,63(2):523-533
[36]Jin.S.,R.S.Wu, andC peng,1998, Prestack depth migation using a hybrid pseudo-screen propagator, 68 `h Ann. Internat. Mtg., Soc. Expl. Geophys., Expanded abstracts,p1819-1822
[37]Jin.S.,R.S.Wu, and peng, seismic depth migration with screen prpagators, Computational Geosciences, 1999,V613:321-355
[38]Mittet,R.,R.sollie, and K. Hokstad, Prestack depth migration with compensation for absorption and dispersion, Geophysics, 1995, Vo160:485 1494.
[39]Kessinger, WP.,1992,Extended spilt-step Fourier migration, 62th Ann. Internat. Mtg., Soc. Expl. Geophys., Expanded abstracts,p917-920
[40]Ristow,D., 3-D implicit finite-differernce migration by multiway splitting, Geophysics, 1997,62(2):554-567
[41]Ristow,D.,and T. ruhl, fourier finite-difference migration Geophysics, 1994, 59(12):1882-1893
[42]stoffa, P.L.,J.1fokkema, R.M.de luna Freire, and W.P. Kessinger, split-step Fourier migration, Geophysics, 1990,55(4):410-421
[43]Stolt, R,H., Migration by Fourier Transform, Geophysics, 1978,43(1):23-48
[44]Zhang Guanquan et al, A new algorithm for finite-difference of steep dips, Geophysics, 1998,Vol53:167-175
[45]Ruhl, Tand Ristow D, 1995,Fourier FD migration: the missing link between phase -shift and FD migration,65`h Annual SEG Mtg, p1232-1234
[46]Samuel H Gray ,et al .Seisimic migration problems and solutions. Geophysics,2001,66(5):1622-1640
[47]Baoniu Han. A comparison of four depth migration methods. 68`h SEG Annual Meeting, 1998 ,p49-76
[48]Gray S H, May W P. kirchhoff migration using eikonal equation travel times. Geophysics, 1994,59(2):810-817
[49]Gray S H,Frequency-selective design of Kirchhoff migration operator,Geophysical Prospecting, 1992,40(4):564-571