利用地震反射和折射联合层析成像探测深部构造方法研究
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摘要
地震层析成像就是用地震数据来反演地下结构的物质属性,并逐层剖析绘制其图像的技术。其主要目的是确定地球内部的精细结构和局部不均匀性(杨文采,1993)。该技术最初是从医学CT理论发展而来的,随着其在地学上的研究不断发展和深入,已经取得了丰硕的成果,因而被越来越多的人接受和推广。
地震层析成像按射线追踪时所用的地震波资料的不同可分为透射波层析、反射波层析、折射波层析、面波层析等。其中透射波层析研究的最为成熟,主要以跨井方式进行观测;其次是折射波层析,其优势在于利用了大偏移距的信息,主要致力于求取近地表风化层的速度和厚度;反射波层析的研究最难,因此最不成熟,虽然其研究范围比折射波层析要深,但是反射波层析受到有限观测角小等问题的影响,因此层析精度不高。为了提高层析成像精度,人们开始将两种以上的地震波资料联合起来进行层析成像研究。
本文首先简述了地震层析成像发展历史及基本原理,分析研究了各种射线追踪和反演算法的优缺点,并将折射层析方程组和反射层析方程组联立起来,进行旅行时联合层析成像。由于综合利用了折射波和反射波的信息,联合层析成像扩大了有限观测角,增加了射线密度,因此理论上其精度要比单一的折射层析或反射层析的精度高。然后本文对Jun Korenaga的折射和反射联合层析成像软件中的网格节点设置方式进行了改进,并进行了两个模型的数值模拟以及一个不同尺度模型的对比试验,模拟结果表明改进后的软件的反演效果有所提高并且广角地震数据比其他数据的层析反演效果好;对比试验结果表明对中等尺度(排列长度几公里以上)及以上的地震数据进行联合层析成像的效果比小尺度(排列长度几公里以内)的地震数据的效果好得多。
Seismic tomography is a technique which deduces and draws the physical properties of underground structure from the inversion of seismic data. Its main purpose is to determine the fine structure of the Earth’s interior and local inhormogeneity ( Wencai Yang, 1993 ). Tomography is originally used in medical research. With the increasing development of geological tomography, the research on geological tomography has achieved great successes and received increasing acceptability and expansion.
According to the differences in the used seismic data, seismic tomography can fall into four types-transmission tomography, reflection tomography, refraction tomography and surface wave tomography. Transmission tomography, which conducts observation in cross-wells, is studied deeper than the other types. It is followed by refraction tomography, of which the advantage is that it utilizes long offset records. Research on reflection tomography is far away from maturity. Although reflection tomography studies deeper subsurface structure than refraction tomography does, it has lower inversion accuracy. In order to improve the inversion accuracy of seismic tomography, researchers begin to carry out simultaneous inversion of two or more types of seismic data.
This paper outlines the development and the basic principles of seismic tomography, and analyzes the advantages and disadvantages of various ray tracing methods and inversion algorithms. This paper also deduces simultaneous tomography equation from reflection tomography equation and refraction tomography equation. The inversion accuracy of simultaneous tomography, in theory, can be improved, since it utilizes both reflection data and refraction data and this combination can increase observation angle. Then this paper improves the distribution of grid nodes in Jun Korenaga’s joint reflection and refraction tomography program, and then carries out numerical simulation with two models. The results show that the improved program has higher inversion accuracy and simultaneous tomography with wide-angle seismic data has better results than other kinds of seismic data. In addition, a comparison experiment is conducted and its result shows that seismic data of intermediate scale and large scale (the length of seismic arrangement is more than several kilometers) is more appropriate for simultaneous tomography than small scale data (the length of seismic arrangement is less than several kilometers).
地震层析成像按射线追踪时所用的地震波资料的不同可分为透射波层析、反射波层析、折射波层析、面波层析等。其中透射波层析研究的最为成熟,主要以跨井方式进行观测;其次是折射波层析,其优势在于利用了大偏移距的信息,主要致力于求取近地表风化层的速度和厚度;反射波层析的研究最难,因此最不成熟,虽然其研究范围比折射波层析要深,但是反射波层析受到有限观测角小等问题的影响,因此层析精度不高。为了提高层析成像精度,人们开始将两种以上的地震波资料联合起来进行层析成像研究。
本文首先简述了地震层析成像发展历史及基本原理,分析研究了各种射线追踪和反演算法的优缺点,并将折射层析方程组和反射层析方程组联立起来,进行旅行时联合层析成像。由于综合利用了折射波和反射波的信息,联合层析成像扩大了有限观测角,增加了射线密度,因此理论上其精度要比单一的折射层析或反射层析的精度高。然后本文对Jun Korenaga的折射和反射联合层析成像软件中的网格节点设置方式进行了改进,并进行了两个模型的数值模拟以及一个不同尺度模型的对比试验,模拟结果表明改进后的软件的反演效果有所提高并且广角地震数据比其他数据的层析反演效果好;对比试验结果表明对中等尺度(排列长度几公里以上)及以上的地震数据进行联合层析成像的效果比小尺度(排列长度几公里以内)的地震数据的效果好得多。
Seismic tomography is a technique which deduces and draws the physical properties of underground structure from the inversion of seismic data. Its main purpose is to determine the fine structure of the Earth’s interior and local inhormogeneity ( Wencai Yang, 1993 ). Tomography is originally used in medical research. With the increasing development of geological tomography, the research on geological tomography has achieved great successes and received increasing acceptability and expansion.
According to the differences in the used seismic data, seismic tomography can fall into four types-transmission tomography, reflection tomography, refraction tomography and surface wave tomography. Transmission tomography, which conducts observation in cross-wells, is studied deeper than the other types. It is followed by refraction tomography, of which the advantage is that it utilizes long offset records. Research on reflection tomography is far away from maturity. Although reflection tomography studies deeper subsurface structure than refraction tomography does, it has lower inversion accuracy. In order to improve the inversion accuracy of seismic tomography, researchers begin to carry out simultaneous inversion of two or more types of seismic data.
This paper outlines the development and the basic principles of seismic tomography, and analyzes the advantages and disadvantages of various ray tracing methods and inversion algorithms. This paper also deduces simultaneous tomography equation from reflection tomography equation and refraction tomography equation. The inversion accuracy of simultaneous tomography, in theory, can be improved, since it utilizes both reflection data and refraction data and this combination can increase observation angle. Then this paper improves the distribution of grid nodes in Jun Korenaga’s joint reflection and refraction tomography program, and then carries out numerical simulation with two models. The results show that the improved program has higher inversion accuracy and simultaneous tomography with wide-angle seismic data has better results than other kinds of seismic data. In addition, a comparison experiment is conducted and its result shows that seismic data of intermediate scale and large scale (the length of seismic arrangement is more than several kilometers) is more appropriate for simultaneous tomography than small scale data (the length of seismic arrangement is less than several kilometers).
引文
[1] Bernasconi.G., Drufuca.G., 3-D traveltimes and amplitudes by gridded rays: Geophysics, 66(1),288-282, 2001
[2] B. Wang and L.W.Braile. Simultaneous inversion of reflection and refraction seismic data and application to field data from the northern Rio Grande rift. Geophys.J.Int. 1996,125: 443~458
[3] Chris Calman and Gerard,T.Schuster. Reflection+Transmission for crosswell tomographic imaging. 59th Annual SEG Meeting, 1989
[4] James W.D.Hobro, Satish C.Singh and Timothy A.Minshull. Three-dimensional tomographyic inversion of combined reflection and refraction seismic traveltime data. Geophys.J.Int. 2003,152: 79~93
[5] Jie Zhang. Nonlinear Refraction and Reflection Traveltime Tomography. PhD.thesis, Massachusetts Institute of Technology. 1997
[6] J.Korenaga, W.S.Holbrook,G.M.Kent, et al.Crustal structure of the southeast Greenland margin from joint refraction and reflection seismic tomography. JOURNAL OF GEOPHYSICAL RESEARCH,105(9): 21591-21614,2000
[7] Kosloff,D. and Sudman,Y. Uncertainty in determining interval velocities from surface reflection seismics, Geophysics, 67(3), 952-963, 2002
[8] McCaughey.M., Singh.S.C., Simultaneous velocity and interface tomography of normal-incidence and wide-aperture sismic traveltime data: Geophysics.J.Int., 131,87-99,1997
[9] Mehmet C.Tanis, Hemang Shah, Peter A.Watson, et al. Diving-wave refraction tomography and reflection tomography for velocity model building. SEG/New Orleans 2006 Annual Meeting, 3340-3344
[10] Moser,T.J.,G.Nolet and R.Snieder, Ray bending revisited, Bull.Seismol.Soc.Am., 82: 259-288,1992
[11] Murphy.G..E. and Gray S.H. Munual seismic reflection tomography: Geophysics, 64(5), 1546-1552. 1999
[12] N.Rawlinson, G.A.Houseman and C.D.N.Collins. Inversion of seismic refraction and wide-angle reflection traveltimes for three-dimensional layered crustal structure. Geophys.J.Int. 2001,145: 381~400
[13] R.P.Singh and E.Nyland. Ray bending due to strong velocity anomalles. Geophysics. 1988,2(53): 201~205
[14] Van Avendonk.H.J.A., Harding.A.J.,et al., Hybrid shortest path and ray bending method for traveltime and raypath calculations. Geophysics, 66(2), 648-653. 2001.
[15] Zhang,H-J., Clidfford H.T. Double-difference tomography: the method and its application to the Hayward fault, California, Bull Seism Soc Amer, 93(5): 1875-1889,2003.
[16]莘海亮,地震层析成像技术方法研究:[硕士学位论文].中国地震局兰州地震研究所,2008
[17]姜勇.波路径旅行时层析成像方法研究:[博士学位论文].中国海洋大学,2006
[18]井西利,杨长春,李幼铭.建立速度模型的层析成像方法研究.石油物探,2002,41(1): 72~75
[19]成谷,地震反射走时层析理论与应用研究:[博士学位论文].同济大学,2004
[20]索重辉,天然地震层析成像方法研究:[硕士学位论文].中国地质大学(北京),2006
[21]常旭,刘伊克.地震正反演与成像.北京:华文出版社. 2001
[22]杨文采,李幼铭.应用地震层析成像.北京:地质出版社. 1993
[23]杨文采.地震物理反演的理论与方法.北京:地质出版社. 1993
[24]吴律.层析基础及其在井间地震中的应用.北京.石油工业出版社. 1997
[25]高星.地震层析成像研究的回顾与展望.地球物理学进展, 15(4):41-45, 2000
[26]黄金莉,刘家琦等.工程物探中地震层析成像的研究.地球物理学报,37(5): 682-687,1994
[27]杨慧珠,聂建华,谭桂华.反射波地震层析成像算法研究.辽宁工程技术大学学报,23(2): 159-161, 2004
[28]雷栋,胡祥云.地震层析成像方法综述.地震研究,29(4): 418-426, 2006
[29]丁志峰.近震层析成像的理论及应用:[博士学位论文].国家地震局地球物理研究所,1999
[30]张建中,陈世军,余大祥.最短路径射线追踪方法及其改进.地球物理学进展,18(1):146-150,2003.
[31]张钋,刘洪,李幼铭.射线追踪方法的发展现状.地球物理学进展, 15(1):36-45
[32]成谷,张宝金.反射地震走时层析成像中的大型稀疏矩阵压缩存储和求解.地球物理学进展,23(3):674-680,2008
[33]潘艳梅,董良国等.近地表速度结构层析反演方法综述.勘探地球物理进展, 29(4): 229-234, 2006
[34]王运生,苏建黎.浅层地震联合成像技术及其应用研究.工程地球物理学报,4(4):306-311, 2007
[35]严又生,宜明理等.井间地震速度和Q值联合层析成像及应用.石油地球物理勘探,36(1): 9-17, 2001
[36]杨淑卿,王立歆等.反射走时及走时梯度联合层析速度反演方法研究.油气地球物理, 6(1): 11-20, 2008
[37]荣立新.应用于金属矿勘查中的地面地震层析成像技术.物化探计算技术,29,增刊: 125-128, 2007
[38]宋炜,罗大清等.双井与地面数据集的透射与反射层析成像.石油地球物理勘探,34(2):148-154, 1999
[39] G.Nolet(王偆镛，吴宁远等编译）.地震层析成像及应用.北京.学术书刊出版社. 1989
[40]王家映.地球物理反演理论[M].北京:高等教育出版社,2002
[41]赵连锋.井间地震波速与衰减联合层析成像方法研究:[博士学位论文].成都:成都理工大学,2002
[42]李盛东,李月华.地震走时层析成像算法与比较.中国矿业大学学报,2000,29(2): 213~214
[43]李胜军,孙成禹,倪长宽等.声波方程有限差分数值模拟的变网格步长算法.工程地球物理学报,2007,4(3):207~212
[44]刘殿秘,韩立国.一种改进的网格射线追踪方法.吉林大学学报,2004,34:77~80
[45]黄剑航.反射波走时及其梯度层析成像方法研究:[硕士学位论文].厦门大学,2008
[2] B. Wang and L.W.Braile. Simultaneous inversion of reflection and refraction seismic data and application to field data from the northern Rio Grande rift. Geophys.J.Int. 1996,125: 443~458
[3] Chris Calman and Gerard,T.Schuster. Reflection+Transmission for crosswell tomographic imaging. 59th Annual SEG Meeting, 1989
[4] James W.D.Hobro, Satish C.Singh and Timothy A.Minshull. Three-dimensional tomographyic inversion of combined reflection and refraction seismic traveltime data. Geophys.J.Int. 2003,152: 79~93
[5] Jie Zhang. Nonlinear Refraction and Reflection Traveltime Tomography. PhD.thesis, Massachusetts Institute of Technology. 1997
[6] J.Korenaga, W.S.Holbrook,G.M.Kent, et al.Crustal structure of the southeast Greenland margin from joint refraction and reflection seismic tomography. JOURNAL OF GEOPHYSICAL RESEARCH,105(9): 21591-21614,2000
[7] Kosloff,D. and Sudman,Y. Uncertainty in determining interval velocities from surface reflection seismics, Geophysics, 67(3), 952-963, 2002
[8] McCaughey.M., Singh.S.C., Simultaneous velocity and interface tomography of normal-incidence and wide-aperture sismic traveltime data: Geophysics.J.Int., 131,87-99,1997
[9] Mehmet C.Tanis, Hemang Shah, Peter A.Watson, et al. Diving-wave refraction tomography and reflection tomography for velocity model building. SEG/New Orleans 2006 Annual Meeting, 3340-3344
[10] Moser,T.J.,G.Nolet and R.Snieder, Ray bending revisited, Bull.Seismol.Soc.Am., 82: 259-288,1992
[11] Murphy.G..E. and Gray S.H. Munual seismic reflection tomography: Geophysics, 64(5), 1546-1552. 1999
[12] N.Rawlinson, G.A.Houseman and C.D.N.Collins. Inversion of seismic refraction and wide-angle reflection traveltimes for three-dimensional layered crustal structure. Geophys.J.Int. 2001,145: 381~400
[13] R.P.Singh and E.Nyland. Ray bending due to strong velocity anomalles. Geophysics. 1988,2(53): 201~205
[14] Van Avendonk.H.J.A., Harding.A.J.,et al., Hybrid shortest path and ray bending method for traveltime and raypath calculations. Geophysics, 66(2), 648-653. 2001.
[15] Zhang,H-J., Clidfford H.T. Double-difference tomography: the method and its application to the Hayward fault, California, Bull Seism Soc Amer, 93(5): 1875-1889,2003.
[16]莘海亮,地震层析成像技术方法研究:[硕士学位论文].中国地震局兰州地震研究所,2008
[17]姜勇.波路径旅行时层析成像方法研究:[博士学位论文].中国海洋大学,2006
[18]井西利,杨长春,李幼铭.建立速度模型的层析成像方法研究.石油物探,2002,41(1): 72~75
[19]成谷,地震反射走时层析理论与应用研究:[博士学位论文].同济大学,2004
[20]索重辉,天然地震层析成像方法研究:[硕士学位论文].中国地质大学(北京),2006
[21]常旭,刘伊克.地震正反演与成像.北京:华文出版社. 2001
[22]杨文采,李幼铭.应用地震层析成像.北京:地质出版社. 1993
[23]杨文采.地震物理反演的理论与方法.北京:地质出版社. 1993
[24]吴律.层析基础及其在井间地震中的应用.北京.石油工业出版社. 1997
[25]高星.地震层析成像研究的回顾与展望.地球物理学进展, 15(4):41-45, 2000
[26]黄金莉,刘家琦等.工程物探中地震层析成像的研究.地球物理学报,37(5): 682-687,1994
[27]杨慧珠,聂建华,谭桂华.反射波地震层析成像算法研究.辽宁工程技术大学学报,23(2): 159-161, 2004
[28]雷栋,胡祥云.地震层析成像方法综述.地震研究,29(4): 418-426, 2006
[29]丁志峰.近震层析成像的理论及应用:[博士学位论文].国家地震局地球物理研究所,1999
[30]张建中,陈世军,余大祥.最短路径射线追踪方法及其改进.地球物理学进展,18(1):146-150,2003.
[31]张钋,刘洪,李幼铭.射线追踪方法的发展现状.地球物理学进展, 15(1):36-45
[32]成谷,张宝金.反射地震走时层析成像中的大型稀疏矩阵压缩存储和求解.地球物理学进展,23(3):674-680,2008
[33]潘艳梅,董良国等.近地表速度结构层析反演方法综述.勘探地球物理进展, 29(4): 229-234, 2006
[34]王运生,苏建黎.浅层地震联合成像技术及其应用研究.工程地球物理学报,4(4):306-311, 2007
[35]严又生,宜明理等.井间地震速度和Q值联合层析成像及应用.石油地球物理勘探,36(1): 9-17, 2001
[36]杨淑卿,王立歆等.反射走时及走时梯度联合层析速度反演方法研究.油气地球物理, 6(1): 11-20, 2008
[37]荣立新.应用于金属矿勘查中的地面地震层析成像技术.物化探计算技术,29,增刊: 125-128, 2007
[38]宋炜,罗大清等.双井与地面数据集的透射与反射层析成像.石油地球物理勘探,34(2):148-154, 1999
[39] G.Nolet(王偆镛，吴宁远等编译）.地震层析成像及应用.北京.学术书刊出版社. 1989
[40]王家映.地球物理反演理论[M].北京:高等教育出版社,2002
[41]赵连锋.井间地震波速与衰减联合层析成像方法研究:[博士学位论文].成都:成都理工大学,2002
[42]李盛东,李月华.地震走时层析成像算法与比较.中国矿业大学学报,2000,29(2): 213~214
[43]李胜军,孙成禹,倪长宽等.声波方程有限差分数值模拟的变网格步长算法.工程地球物理学报,2007,4(3):207~212
[44]刘殿秘,韩立国.一种改进的网格射线追踪方法.吉林大学学报,2004,34:77~80
[45]黄剑航.反射波走时及其梯度层析成像方法研究:[硕士学位论文].厦门大学,2008