基于虚源估计的复杂上覆地层下地震相干成像
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摘要
在上覆地层比较复杂的情况下,常规地震勘探方法常常难以得到好的成像.本文研究了基于地震相干避开复杂上覆地层对地震波的影响,利用VSP数据估计地震虚源直接对目的地层进行成像的方法.在地震相干成像过程中,震源子波对分辨率有比较大的影响,尤其是存在薄层的条件下,两个非常近的反射同相轴将无法辨认.利用估计出虚源地震子波的性质,对该子波进行整形压制其旁瓣,从而提高成像的分辨率.针对典型模型的数值试验结果表明,对于复杂上覆地层情形,通过从VSP数据估计的虚源数据能够较好的对目的地层进行成像.
Under the conditions of complex overburden,the results of conventional seismic exploration methods are always not good enough.Based on seismic interferometry,this paper studies a way to avoid the complex overburden and image the target stratum directly with virtual source generated from VSP data.The wavelet of the source affects the resolution of the seismic interferometric imaging,especially when there is a thin layer,which makes the distinguishing of the closely approached reflect events impossible.Based on the characteristics of the estimated virtual source wavelet,the wavelet is shaped to suppress the side lobes of the wavelet to improve the resolution of imaging.The numerical experiment shows that with complex overburden,the virtual source data generated from the VSP data can give a good image of the target stratum.
Under the conditions of complex overburden,the results of conventional seismic exploration methods are always not good enough.Based on seismic interferometry,this paper studies a way to avoid the complex overburden and image the target stratum directly with virtual source generated from VSP data.The wavelet of the source affects the resolution of the seismic interferometric imaging,especially when there is a thin layer,which makes the distinguishing of the closely approached reflect events impossible.Based on the characteristics of the estimated virtual source wavelet,the wavelet is shaped to suppress the side lobes of the wavelet to improve the resolution of imaging.The numerical experiment shows that with complex overburden,the virtual source data generated from the VSP data can give a good image of the target stratum.
引文
[1] Claerbout J F. Synthesis of a layered medium from its acoustic transmission response. Geophysics, 1968, 33(2) :264-269
[2] Katz L J. Inverse vertical seismic profiling while drilling:United States Patent, Patent Number: 5,012,453, 1991
[3] Rickett J, Claerbout J. Passive seismic imaging applied to synthetic data. Stanford Exploration Project. 1996． 87-94
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[5] Schuster G T, Yu J, Sheng J, et al. Inlerferometric/daylight seismic imaging. Geophys. J. Int., 2004, 157(2) : 838-852
[6] Draganov D, Ghose R, Ruigrok E, et al. Seismic interferometry, intrinsic losses and Q-estimation. Geophysical Prospecting ,2010, 58(3) : 361-373
[7] Bakulin A, Calvert R. Virtual source; New method for imaging and 4D below complex overburden. 74th Annual Meeting, SEG Expanded Abstracts. 2004． 2477-2480
[8] Chavarria J A, Goertz A, Karrenbach M, et al. The use of VSP techniques for fault zone characterization; An example from the San Andreas Fault. The Leading Edge, 2007, 26(6) : 770-776
[9] Bakulin A, Calvert R. The virtual source method: Theory and case study. Geophysics, 2006, 71(4) : S1139-S1150
[10] Halliday D F, Curtis A, Robertsson J O A, et al.Interferometric surface-wave isolation and removal. Geophysics, 2007, 72(5) : A69-A73
[11] Wapenaar K. Retrieving the elastodynamic Green s function of an arbitrary inhomogeneous medium by cross correlation.Physical Review Letters , 2004, 93(25) : 254301
[12] Wapenaar K, Fokkema J. Green s function representations for seismic interferometry. Geophysics, 2006, 71(4) : SI33-SI46
[13] Snieder R. Extracting the Green s function of attenuating heterogeneous media from uncorrelated waves. J. Acoust.Soc. Am. , 2007, 121(5) :2637-2643
[14] Wapenaar K, Slob E, Snieder R. Seismic and electromagnetic controlled-source interferometry in dissipative media.Geophysical Prospecting , 2008, 56(3) : 419-434
[15] Vasconcelos I, Snieder R. Interferometry by deconvolution:Part2-Theory for elastic waves and application to drill-bit seismic imaging. Geophysics, 2008, 73(3) : S129-S141
[16] 常旭,刘伊克,王辉等.地震相干偏移与数据自参照偏移的关系.地球物理学报,2009,52(11) :2840～2845Chang X, Liu Y K, Wang H, et al. Seismic interferometric migration and data-referenced-only migration. Chinese J.Geophys. (in Chinese), 2009, 52(11) : 2840-2845
[17] Schuster G T. Seismic Interferometry. Cambridge; Cambridge University Press, 2009． 30-60
[18] Mehta K, Snieder R, Calvert R, et al. Acquisition geometry requirements for generating virtual-source data. The Leading Edge, 2008, 27(5) : 620-629
[2] Katz L J. Inverse vertical seismic profiling while drilling:United States Patent, Patent Number: 5,012,453, 1991
[3] Rickett J, Claerbout J. Passive seismic imaging applied to synthetic data. Stanford Exploration Project. 1996． 87-94
[4] Schuster G T. Theory of Daylight/lnterferometric Imaging:Tutorial. 63rd annual EAGE meeting, Expanded Abstracts. Salt Lake City, University of Utah, 2001, A-32
[5] Schuster G T, Yu J, Sheng J, et al. Inlerferometric/daylight seismic imaging. Geophys. J. Int., 2004, 157(2) : 838-852
[6] Draganov D, Ghose R, Ruigrok E, et al. Seismic interferometry, intrinsic losses and Q-estimation. Geophysical Prospecting ,2010, 58(3) : 361-373
[7] Bakulin A, Calvert R. Virtual source; New method for imaging and 4D below complex overburden. 74th Annual Meeting, SEG Expanded Abstracts. 2004． 2477-2480
[8] Chavarria J A, Goertz A, Karrenbach M, et al. The use of VSP techniques for fault zone characterization; An example from the San Andreas Fault. The Leading Edge, 2007, 26(6) : 770-776
[9] Bakulin A, Calvert R. The virtual source method: Theory and case study. Geophysics, 2006, 71(4) : S1139-S1150
[10] Halliday D F, Curtis A, Robertsson J O A, et al.Interferometric surface-wave isolation and removal. Geophysics, 2007, 72(5) : A69-A73
[11] Wapenaar K. Retrieving the elastodynamic Green s function of an arbitrary inhomogeneous medium by cross correlation.Physical Review Letters , 2004, 93(25) : 254301
[12] Wapenaar K, Fokkema J. Green s function representations for seismic interferometry. Geophysics, 2006, 71(4) : SI33-SI46
[13] Snieder R. Extracting the Green s function of attenuating heterogeneous media from uncorrelated waves. J. Acoust.Soc. Am. , 2007, 121(5) :2637-2643
[14] Wapenaar K, Slob E, Snieder R. Seismic and electromagnetic controlled-source interferometry in dissipative media.Geophysical Prospecting , 2008, 56(3) : 419-434
[15] Vasconcelos I, Snieder R. Interferometry by deconvolution:Part2-Theory for elastic waves and application to drill-bit seismic imaging. Geophysics, 2008, 73(3) : S129-S141
[16] 常旭,刘伊克,王辉等.地震相干偏移与数据自参照偏移的关系.地球物理学报,2009,52(11) :2840～2845Chang X, Liu Y K, Wang H, et al. Seismic interferometric migration and data-referenced-only migration. Chinese J.Geophys. (in Chinese), 2009, 52(11) : 2840-2845
[17] Schuster G T. Seismic Interferometry. Cambridge; Cambridge University Press, 2009． 30-60
[18] Mehta K, Snieder R, Calvert R, et al. Acquisition geometry requirements for generating virtual-source data. The Leading Edge, 2008, 27(5) : 620-629
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