库车坳陷复杂高陡构造地震成像研究
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摘要
复杂构造地震成像主要取决于叠前地震数据品质、偏移速度可靠性和偏移算子成像精度.库车坳陷异常复杂的近地表条件导致极低信噪比的地震采集数据.该区逆冲推覆高陡构造刺穿盐体大面积分布,盐层厚度变化大、顶底面形态复杂,盐下断裂带破碎、小断块发育,形成异常复杂的地震成像问题.本文重点研究三个关键环节:(1)精细的叠前地震预处理研究:根据该区地震地质复杂性和地震资料特征,采用一些新的方法技术和技术组合从振幅与时移的大、中、小尺度变化三个层次来解决资料信噪比问题,重建深部反射信号;(2)三级偏移速度分析研究:利用库车坳陷盐刺穿逆冲推覆构造建模理论及变速成图配套技术解决叠前时间偏移速度场时深转换问题,利用井约束低频速度地震迭代反演技术解决连井层速度场与偏移速度场的融合问题,实现从DMO速度分析、叠前时间偏移速度分析到叠前深度偏移速度分析的有机衔接,建立拓扑结构相对保持的叠前深度偏移速度模型;(3)基于退化Fourier偏移算子的半解析波动方程叠前时间和深度偏移研究,极大地改善了地震偏移过程中高波数波的成像问题.通过对库车坳陷大北、博孜、却勒、西秋4和西秋10等复杂高陡构造的叠前时间和深度偏移地震成像处理,取得了较好的应用效果.
Seismic imaging generally depends on data quality, velocity reliability, and migrator performance. Complex near-surface geological conditions in Kuqa depression cause extremely low signal-to-noise (S/N) ratios of seismic data. Salts penetrated into overthrust structures are widely distributed, vary in thickness and shape of complex geometries, and distort the imaging of subsalt faults, leading to complicated imaging problems. This article studies three key aspects. In the preprocessing of prestack data, some innovative techniques combined with commercial techniques are employed by three levels to improve data quality and reconstruct the reflections from depths. Three-stage migration velocity analyses, subtle DMO velocity analysis, prestack time-migration, and prestack depth-migration velocity analyses are implemented to build a topology-preservation prestack-migration velocity model. The time-depth conversion of the prestack time-migration velocity model is performed based on the Kuqa-depression modeling theory of salt-related overthrust complex structures combined with the velocity-varying mapping technique. The well-constrained seismic inversion for low-frequency velocities is conducted to handle the syncretization of the well-building and migration-building velocity fields. Finally, prestack time and depth migrations are performed by a semi-analytic degenerate Fourier migrator that improves the imaging of high-wavenumber components. Applications to the Dabei, Bozi, Quele, Xiqiu10, and Xiqiu4 structures result in well-positioned images for salt-related overthrust complex structures.
Seismic imaging generally depends on data quality, velocity reliability, and migrator performance. Complex near-surface geological conditions in Kuqa depression cause extremely low signal-to-noise (S/N) ratios of seismic data. Salts penetrated into overthrust structures are widely distributed, vary in thickness and shape of complex geometries, and distort the imaging of subsalt faults, leading to complicated imaging problems. This article studies three key aspects. In the preprocessing of prestack data, some innovative techniques combined with commercial techniques are employed by three levels to improve data quality and reconstruct the reflections from depths. Three-stage migration velocity analyses, subtle DMO velocity analysis, prestack time-migration, and prestack depth-migration velocity analyses are implemented to build a topology-preservation prestack-migration velocity model. The time-depth conversion of the prestack time-migration velocity model is performed based on the Kuqa-depression modeling theory of salt-related overthrust complex structures combined with the velocity-varying mapping technique. The well-constrained seismic inversion for low-frequency velocities is conducted to handle the syncretization of the well-building and migration-building velocity fields. Finally, prestack time and depth migrations are performed by a semi-analytic degenerate Fourier migrator that improves the imaging of high-wavenumber components. Applications to the Dabei, Bozi, Quele, Xiqiu10, and Xiqiu4 structures result in well-positioned images for salt-related overthrust complex structures.
引文
[1]阎世信,刘怀山,姚雪根.山地地球物理勘探技术.北京:石油工业出版,2001.Yan S X,Liu H S,Yao X G.Mountain GeophysicalExploration Technology(in Chinese).Beijing:PetroleumIndustry Press,2001.
[2]苟量.中国西部复杂山地山前带地震勘探应用技术研究[博士论文].四川:成都理工大学,2005.Gou L.Studies on seismic exploration technology in thecomplex regions of western China[Ph.D.thesis](inChinese).Sichuan:Chengdu University of Technology,2005.
[3]王西文,高建虎,刘伟方等.复杂地区地震勘探实践.北京:石油工业出版,2010.Wang X W,Gao J H,Liu W F,et al.Seismic ExplorationPractice in Complex Regions(in Chinese).Beijing:PetroleumIndustry Press,2010.
[4]雷刚林,张国伟,刘志宏.库车前陆逆冲带生长地层及其在油气勘探中的意义.新疆石油地质,2001,22(2):107-110.Lei G L,Zhang G W,Liu Z H.The growth formation ofKuqa foreland overthrust belt and its application in oil-gasexploration.Xinjiang Petroleum Geology(in Chinese),2001,22(2):107-110.
[5]何光玉,卢华复,李树新.库车盆地秋里塔格构造带构造圈闭及油气勘探方向.地质科学,2003,38(4):506-510.He G Y,Lu H F,Li S X.Structure traps and petroleumexploration potentials of the Qiulitage structure belt in theKuqa basin NW China.Chinese Journal of Geology(in Chinese),2003,38(4):506-510.
[6]董文,符力耘,肖又军等.库车坳陷高陡构造地震勘探复杂性定量分析.地球物理学报,2011,54(6):1600-1613.Dong W,Fu L Y,Xiao Y J,et al.Quantitative analysis ofthe complexity in seismic exploration of the high and steepstructures in Kuqa depression.Chinese J.Geophys.(in Chinese),2011,54(6):1600-1613.
[7]Fu L Y.Quantitative assessment of the complexity ofgeological structures in terms of seismic propagators.Sci.China Earth Sci.,2010,53(1):54-63.
[8]李庆忠.走向精确勘探的道路.北京:石油工业出版,1993.Li Q Z.To the Way of the Accurate Exploration(inChinese).Beijing:Petroleum Industry Press,1993.
[9]Fu L Y.Comparison of different one-way propagators forwave forward propagation in heterogeneous crustal waveguides.Bull.Seismol.Soc.Am.,2006,96(3):1091-1113.
[10]符力耘,孙伟家,李东平.退化的Fourier偏移算子及其在复杂断块成像中的应用.地球物理学报,2007,50(4):1241-1250.Fu L Y,Sun W J,Li D P.Degenerate migrators for imagingfault-related complex structures.Chinese J.Geophys.(inChinese),2007,50(4):1241-1250.
[11]Stoffa P L,Fakkema J T,de Luna Freire R M,et al.Split-step Fourier migration.Geophysics,1990,54(4):410-421.
[12]段玉,符力耘,刘德健.利用FKSUB消除局部规则干扰波.石油地球物理勘探,1996,31(6):874-884.Duan Y,Fu L Y,Liu D J.Local regular noise eliminationusing FKSUB model.Oil Geophysical Prospecting(in Chinese),1996,31(6):874-884.
[13]卢回忆,符力耘,蒋韬.快速Fourier变换波动方程基准面校正方法研究.地球物理学进展,2010,25(4):1313-1322.Lu H Y,Fu L Y,Jiang T.Wave-equation datuming based onfast Fourier transform.Progress in Geophysics(in Chinese),2010,25(4):1313-1322.
[14]胡自多,吕锡敏,王建华.库车地区高陡构造低信噪比资料处理方法研究.石油地球物理勘探,2002,37(1):108-117.Hu Z D,LüX M,Wang J H.Studies on processing seismicdata with low signal-to-noise ratio in Kuqa region.OilGeophysical Prospecting(in Chinese),2002,37(1):108-117.
[15]符力耘,牟永光.弹性波边界元法正演模拟.地球物理学报,1994,37(4):521-529.Fu LY,Mu Y G.Boundary element method for elastic waveforward modeling.Chinese J.Geophys.(in Chinese),1994,37(4):521-529.
[16]贺振华,王才经,何樵登等.反射地震资料偏移处理与反演方法.重庆:重庆大学出版社,1989.He Z H,Wang C J,He Q D,et al.Reflection Seismic DataMigration Processing and Inversion Method(in Chinese).Chongqing:Chongqing University Press,1989.
[17]贾承造.中国塔里木盆地构造特征与油气.北京:石油工业出版社,1997.Jia C Z.Tectonic Characteristics and Oil/Gas in Tarim Basin,China(in Chinese).Beijing:Petroleum Industry Press,1997.
[18]卢华复,贾承造.库车-柯坪再生前陆冲断带构造.北京:科学出版社,2003.Lu H F,Jia C Z.Kuqa-Keping Foreland Thrust BeltStructures(in Chinese).Beijing:Science Press,2003.
[19]汤良杰,雷刚林.却勒—西秋地区构造形成机制与构造建模研究.塔里木油田分公司和中国石油大学(北京),2005(内部报告).Tang L J,Lei G L.Studies on structure movements andmodel buildings in Quele-Xiqiu region(in Chinese).PetroChina Tarim Oilfield Company and China University ofPetroleum(Beijing),2005(internal report).
[20]王清华,杨明慧,吕修祥.库车褶皱冲断带秋里塔格构造带东、西分段构造特征与油气聚集.地质科学,2004,39(4):523-531.Wang H Q,Yang M H,LüX X.Features of structuralsegmentation and accumunation of oil and gas in the Qiulitagestructural belt,Kuqa fold-and-thrust belt.Chinese Journalof Geology(in Chinese),2004,39(4):523-531.
[21]Fu L Y.Joint inversions of seismic data for acousticimpedance.Geophysics,2004,69(4):994-1004.
[22]吴媚,李维新,符力耘.基于测井曲线分频分析的地震反演.石油地球物理勘探,2007,42(1):65-71Wu M,Li W X,Fu L Y.Seismic inversions based on loggingtrace frequency-shared analysis.Oil Geophysical Prospecting(in Chinese),2007,42(1):65-71.
[23]Gazdag J,Sguazzero P.Migration of seismic data by phaseshift plus interpolation.Geophysics,1984,49(2):124-131.
[24]Kessinger W.Extended split-step Fourier migration.62ndAnn.Internat.Mtg.,Soc.Expl.Geophys.,Expanded Abstracts,1992:917-920.
[25]Wu R S,Jin S.Windowed GSP(generalized screenpropagators)migration applied to SEG-EAEG salt modeldata.67th Ann.Internat.Mtg.,Soc.Expl.Geophys.,ExpandedAbstracts,1997:1746-1749.
[2]苟量.中国西部复杂山地山前带地震勘探应用技术研究[博士论文].四川:成都理工大学,2005.Gou L.Studies on seismic exploration technology in thecomplex regions of western China[Ph.D.thesis](inChinese).Sichuan:Chengdu University of Technology,2005.
[3]王西文,高建虎,刘伟方等.复杂地区地震勘探实践.北京:石油工业出版,2010.Wang X W,Gao J H,Liu W F,et al.Seismic ExplorationPractice in Complex Regions(in Chinese).Beijing:PetroleumIndustry Press,2010.
[4]雷刚林,张国伟,刘志宏.库车前陆逆冲带生长地层及其在油气勘探中的意义.新疆石油地质,2001,22(2):107-110.Lei G L,Zhang G W,Liu Z H.The growth formation ofKuqa foreland overthrust belt and its application in oil-gasexploration.Xinjiang Petroleum Geology(in Chinese),2001,22(2):107-110.
[5]何光玉,卢华复,李树新.库车盆地秋里塔格构造带构造圈闭及油气勘探方向.地质科学,2003,38(4):506-510.He G Y,Lu H F,Li S X.Structure traps and petroleumexploration potentials of the Qiulitage structure belt in theKuqa basin NW China.Chinese Journal of Geology(in Chinese),2003,38(4):506-510.
[6]董文,符力耘,肖又军等.库车坳陷高陡构造地震勘探复杂性定量分析.地球物理学报,2011,54(6):1600-1613.Dong W,Fu L Y,Xiao Y J,et al.Quantitative analysis ofthe complexity in seismic exploration of the high and steepstructures in Kuqa depression.Chinese J.Geophys.(in Chinese),2011,54(6):1600-1613.
[7]Fu L Y.Quantitative assessment of the complexity ofgeological structures in terms of seismic propagators.Sci.China Earth Sci.,2010,53(1):54-63.
[8]李庆忠.走向精确勘探的道路.北京:石油工业出版,1993.Li Q Z.To the Way of the Accurate Exploration(inChinese).Beijing:Petroleum Industry Press,1993.
[9]Fu L Y.Comparison of different one-way propagators forwave forward propagation in heterogeneous crustal waveguides.Bull.Seismol.Soc.Am.,2006,96(3):1091-1113.
[10]符力耘,孙伟家,李东平.退化的Fourier偏移算子及其在复杂断块成像中的应用.地球物理学报,2007,50(4):1241-1250.Fu L Y,Sun W J,Li D P.Degenerate migrators for imagingfault-related complex structures.Chinese J.Geophys.(inChinese),2007,50(4):1241-1250.
[11]Stoffa P L,Fakkema J T,de Luna Freire R M,et al.Split-step Fourier migration.Geophysics,1990,54(4):410-421.
[12]段玉,符力耘,刘德健.利用FKSUB消除局部规则干扰波.石油地球物理勘探,1996,31(6):874-884.Duan Y,Fu L Y,Liu D J.Local regular noise eliminationusing FKSUB model.Oil Geophysical Prospecting(in Chinese),1996,31(6):874-884.
[13]卢回忆,符力耘,蒋韬.快速Fourier变换波动方程基准面校正方法研究.地球物理学进展,2010,25(4):1313-1322.Lu H Y,Fu L Y,Jiang T.Wave-equation datuming based onfast Fourier transform.Progress in Geophysics(in Chinese),2010,25(4):1313-1322.
[14]胡自多,吕锡敏,王建华.库车地区高陡构造低信噪比资料处理方法研究.石油地球物理勘探,2002,37(1):108-117.Hu Z D,LüX M,Wang J H.Studies on processing seismicdata with low signal-to-noise ratio in Kuqa region.OilGeophysical Prospecting(in Chinese),2002,37(1):108-117.
[15]符力耘,牟永光.弹性波边界元法正演模拟.地球物理学报,1994,37(4):521-529.Fu LY,Mu Y G.Boundary element method for elastic waveforward modeling.Chinese J.Geophys.(in Chinese),1994,37(4):521-529.
[16]贺振华,王才经,何樵登等.反射地震资料偏移处理与反演方法.重庆:重庆大学出版社,1989.He Z H,Wang C J,He Q D,et al.Reflection Seismic DataMigration Processing and Inversion Method(in Chinese).Chongqing:Chongqing University Press,1989.
[17]贾承造.中国塔里木盆地构造特征与油气.北京:石油工业出版社,1997.Jia C Z.Tectonic Characteristics and Oil/Gas in Tarim Basin,China(in Chinese).Beijing:Petroleum Industry Press,1997.
[18]卢华复,贾承造.库车-柯坪再生前陆冲断带构造.北京:科学出版社,2003.Lu H F,Jia C Z.Kuqa-Keping Foreland Thrust BeltStructures(in Chinese).Beijing:Science Press,2003.
[19]汤良杰,雷刚林.却勒—西秋地区构造形成机制与构造建模研究.塔里木油田分公司和中国石油大学(北京),2005(内部报告).Tang L J,Lei G L.Studies on structure movements andmodel buildings in Quele-Xiqiu region(in Chinese).PetroChina Tarim Oilfield Company and China University ofPetroleum(Beijing),2005(internal report).
[20]王清华,杨明慧,吕修祥.库车褶皱冲断带秋里塔格构造带东、西分段构造特征与油气聚集.地质科学,2004,39(4):523-531.Wang H Q,Yang M H,LüX X.Features of structuralsegmentation and accumunation of oil and gas in the Qiulitagestructural belt,Kuqa fold-and-thrust belt.Chinese Journalof Geology(in Chinese),2004,39(4):523-531.
[21]Fu L Y.Joint inversions of seismic data for acousticimpedance.Geophysics,2004,69(4):994-1004.
[22]吴媚,李维新,符力耘.基于测井曲线分频分析的地震反演.石油地球物理勘探,2007,42(1):65-71Wu M,Li W X,Fu L Y.Seismic inversions based on loggingtrace frequency-shared analysis.Oil Geophysical Prospecting(in Chinese),2007,42(1):65-71.
[23]Gazdag J,Sguazzero P.Migration of seismic data by phaseshift plus interpolation.Geophysics,1984,49(2):124-131.
[24]Kessinger W.Extended split-step Fourier migration.62ndAnn.Internat.Mtg.,Soc.Expl.Geophys.,Expanded Abstracts,1992:917-920.
[25]Wu R S,Jin S.Windowed GSP(generalized screenpropagators)migration applied to SEG-EAEG salt modeldata.67th Ann.Internat.Mtg.,Soc.Expl.Geophys.,ExpandedAbstracts,1997:1746-1749.
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