广角反射波的特征及正演模拟
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摘要
对于高速屏蔽层下伏的低速层,采用广角地震勘探是一种有效的地震勘探方法。但在广角条件下,反射波与入射波存在相位差,反射系数变为复数,波动力学特征非常复杂,给实际地震资料的识别、处理、解释带来困难。在介质弹性参数λ,μ和σ确定、波速与密度相对变化的条件下,本文从Zoeppritz方程出发,运用数值模拟的方法模拟了超临界角地震波的传播规律。表明当P波入射角等于或大于临界角时,波的性质发生变化,反射系数成为复数,地面难以接收,而透射S波能量较强,可利用转换波探测高速屏蔽层下伏低速层界面的信息;采用带有各向异性参数的四阶动校正公式(Alkhalifah方法、Hake公式、Castle公式)对大炮检距的地震数据进行校正,验证了带有各向异性参数的高阶动校正在大炮检距处的校正效果明显优于常规动校正效果。
For underlying lower-velocity layers shielded by high-velocity layers, the wide-angle seismic exploration is effective seismic exploration approach. But under the wide-angle condition, the phase difference exists between the reflected and incident waves,making the reflection coefficients complex and the feature of wave dynamics very complicated, bringing difficulty to identification, processing and interpretation of practical seismic data. In the conditions that the elastic parameters of medium λ,μ and σ are determined,wave velocity and dense of medium relatively change, the paper, coming from the Zoeppritz equation, uses the method of numeric simulation to simulate the propagation rule of supercritical seismic waves, which showed,when P-wave incident angles are equal to or great than critical angle, the properties of wave change, the reflection coefficients become complex, which made receiving of reflections on surface difficult,but the transmitted S-wave has strong energy that can be used for detection of information in underlying low-velocity layers shielded by high-velocity layers. It is proved, by using 4-order NMO formula with anisotropic parameters (Alkhalifah method, Hake formula and Castle formula) to carry out correction for seismic data with large offsets, the corrected effects of high-order NMO formula with anisotropic parameters are obviously superior to that of ordinary NMO formula at large offsets.
For underlying lower-velocity layers shielded by high-velocity layers, the wide-angle seismic exploration is effective seismic exploration approach. But under the wide-angle condition, the phase difference exists between the reflected and incident waves,making the reflection coefficients complex and the feature of wave dynamics very complicated, bringing difficulty to identification, processing and interpretation of practical seismic data. In the conditions that the elastic parameters of medium λ,μ and σ are determined,wave velocity and dense of medium relatively change, the paper, coming from the Zoeppritz equation, uses the method of numeric simulation to simulate the propagation rule of supercritical seismic waves, which showed,when P-wave incident angles are equal to or great than critical angle, the properties of wave change, the reflection coefficients become complex, which made receiving of reflections on surface difficult,but the transmitted S-wave has strong energy that can be used for detection of information in underlying low-velocity layers shielded by high-velocity layers. It is proved, by using 4-order NMO formula with anisotropic parameters (Alkhalifah method, Hake formula and Castle formula) to carry out correction for seismic data with large offsets, the corrected effects of high-order NMO formula with anisotropic parameters are obviously superior to that of ordinary NMO formula at large offsets.
引文
[1]Jisoo V Ryu.Seeing through seismically difficult rocks unconventionally.Geophysics,1997,62:1177~1182
[2]Haugen G Uand Yu F.Can seismic wide-aperture da-ta i mage beneath basalt?Expanded Abstracts of68th SEG Mtg,1998,90~93
[3]Fruehn J et al.Flare-Atwo-ship experi ment designed for sub-basalt i maging.Expanded Abstracts of68thSEG Mtg,1998,94~97
[4]Li X Yet al.Using converted shear-wave for i maging beneath basalt in deep water plays.Expanded Ab-stracts of68th SEG Mtg,1998,1369~1372
[5]Makris J et al.WARRP(Wide Aperture Reflection and Refraction Profiling):The principle of successful data acquisition where conventional seismic fails.Ex-panded Abstracts of69th SEG Mtg,1999,989~992
[6]Epili D et al.3-D WARRP design for exploration tar-gets.Expanded Abstracts of69th SEG Mtg,1999,985~988
[7]Wombell Ret al.Long offset acquisition and process-ing for sub-basalt i maging.Expanded Abstracts of69th SEG Mtg,1999,1429~1432
[8]Fliedner Mand White R.Using wide-angle seismic da-ta for basalt and sub-basalt i maging.Expanded Ab-stracts of69th SEG Mtg,1999,1021~1024
[9]Bennett Geoff.3-Dseismic refraction for deep explo-ration targets.The Leading Edge,1999,18:186~191
[10]胡中平等.高速屏蔽层下广角地震波场分析及成像方法.地球物理学报,2004,47(1):88~94
[11]薛冈等.VTI介质P波反射时差分析.石油地球物理勘探,2004,39(2):144~148
[12]甘永忠.广角层速度分析.石油物探,1994
[13]刘财等.极化滤波在广角地震P、S波场分离中的应用.物探化探计算技术,1995,17(2):15~18
[14]胡中平.优化六次项NMO校正方法研究.石油地球物理勘探,2003,38(6):603~607
[15]王志等.广角反射波场特征研究及正演模拟分析.地球物理学进展,2003,18(1):116~121
[16][美]R E谢里夫,[加]L P吉尔达特,初英等译.勘探地震学(第二版).北京:石油工业出版社,1999
[17]Alkhalifah T and Tsvankin I.Velocity analysis for trans-versely isotropic media.Geophysics,1995,60:1550~1566
[18]Hake H et al.Three-term Taylor series fort2-x2curves over layered transversely isotropic ground.Geophy Prosp,1984,32
[19]Castle RJ.Atheory of normal moveout.Geophysics,1994,59:983~999
[20]Siliqi R and Bousquie N.Anelliptic ti me processing based on a shifted hyperbola approach.Expanded Ab-stracts of70th SEG Mtg,2000,2245~2248
[21]Taner M T and Koehler F.Velocity spectradigital com-puter derivation and application of velocity func-tion.Geophysics,1969,34:859~881
[2]Haugen G Uand Yu F.Can seismic wide-aperture da-ta i mage beneath basalt?Expanded Abstracts of68th SEG Mtg,1998,90~93
[3]Fruehn J et al.Flare-Atwo-ship experi ment designed for sub-basalt i maging.Expanded Abstracts of68thSEG Mtg,1998,94~97
[4]Li X Yet al.Using converted shear-wave for i maging beneath basalt in deep water plays.Expanded Ab-stracts of68th SEG Mtg,1998,1369~1372
[5]Makris J et al.WARRP(Wide Aperture Reflection and Refraction Profiling):The principle of successful data acquisition where conventional seismic fails.Ex-panded Abstracts of69th SEG Mtg,1999,989~992
[6]Epili D et al.3-D WARRP design for exploration tar-gets.Expanded Abstracts of69th SEG Mtg,1999,985~988
[7]Wombell Ret al.Long offset acquisition and process-ing for sub-basalt i maging.Expanded Abstracts of69th SEG Mtg,1999,1429~1432
[8]Fliedner Mand White R.Using wide-angle seismic da-ta for basalt and sub-basalt i maging.Expanded Ab-stracts of69th SEG Mtg,1999,1021~1024
[9]Bennett Geoff.3-Dseismic refraction for deep explo-ration targets.The Leading Edge,1999,18:186~191
[10]胡中平等.高速屏蔽层下广角地震波场分析及成像方法.地球物理学报,2004,47(1):88~94
[11]薛冈等.VTI介质P波反射时差分析.石油地球物理勘探,2004,39(2):144~148
[12]甘永忠.广角层速度分析.石油物探,1994
[13]刘财等.极化滤波在广角地震P、S波场分离中的应用.物探化探计算技术,1995,17(2):15~18
[14]胡中平.优化六次项NMO校正方法研究.石油地球物理勘探,2003,38(6):603~607
[15]王志等.广角反射波场特征研究及正演模拟分析.地球物理学进展,2003,18(1):116~121
[16][美]R E谢里夫,[加]L P吉尔达特,初英等译.勘探地震学(第二版).北京:石油工业出版社,1999
[17]Alkhalifah T and Tsvankin I.Velocity analysis for trans-versely isotropic media.Geophysics,1995,60:1550~1566
[18]Hake H et al.Three-term Taylor series fort2-x2curves over layered transversely isotropic ground.Geophy Prosp,1984,32
[19]Castle RJ.Atheory of normal moveout.Geophysics,1994,59:983~999
[20]Siliqi R and Bousquie N.Anelliptic ti me processing based on a shifted hyperbola approach.Expanded Ab-stracts of70th SEG Mtg,2000,2245~2248
[21]Taner M T and Koehler F.Velocity spectradigital com-puter derivation and application of velocity func-tion.Geophysics,1969,34:859~881
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