延时参数对地震信号信噪比的改善
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摘要
当测区噪声很强,采用组合震源工作仍然不能得到高质量地震数据,为进一步提高地震信号的信噪比,引入能形成定向地震波的相控震源.相控震源产生的地震波方向可由延时参数控制,因此延时参数是影响相控地震效果的重要参数.理论分析表明,定向地震波技术可提高反射波信号信噪比,以含3个激震器的相控震源为例,信噪比可提高6.53～9.54 dB.针对延时参数分别为0,0.802,0.384,0.241,0.1 74,0.123 ms的情况,完成了野外地震实验.根据原始地震记录,得到了反射波信号功率谱,在此基础上定量地计算了不同延时参数下目标层反射信号的信噪比.结果表明,与单震源情况相比,在6种延时参数下,反射波信噪比分别提高了3.3150,8.0150,6.0547,5.0278,4.5383,4.0364 dB;与组合震源情况相比,信噪比分别提高了0,4.7000,2.7397,1.7128,1.2233,0.7214 dB.综合理论分析及野外实验结果,我们可以得到这样的结论:定向地震波技术能够提高反射波信号信噪比,延时参数变化对信噪比有很大影响,采用合理的延时参数能得到更高的信噪比.
When noise in the field is strong,it's difficult to obtain high SNR seismic data with single or combination vibrator.So phased array vibrator system (PAVS),which can form directional seismic beam,was developed.Because the orientation of the directional seismic wave is dependent on the time delay,the time delay is a dominant factor for PAVS to boost SNR of reflected signals.3-unit PAVS is able to improve SNR by 6.53～9.54 dB based on theoretical analysis.Field seismic data were obtained for time delays 0,0.802,0.384,0.241,0.174,and 0.123 ms respectively.Using the raw data with different time delays,the power spectrums of reflected seismic signals were calculated,and then quantitative SNR improvement is obtained. Compared to the ease of single source,SNR increased by 3.3150,8.0150,6.0547,5.0278,4.5383,and 4.0364 dB,respectively.Compared to the case of combination source,SNR increased by 0, 4.7000,2.7397,1.7128,1.2233,and 0.7214 dB,respectively.On the basis of theoretical analysis and the results of field experiment,it concludes that directional seismic beam technique is useful to SNR improvement,SNR varies with time delay,proper time delay can raise SNR of reflected signals significantly.
When noise in the field is strong,it's difficult to obtain high SNR seismic data with single or combination vibrator.So phased array vibrator system (PAVS),which can form directional seismic beam,was developed.Because the orientation of the directional seismic wave is dependent on the time delay,the time delay is a dominant factor for PAVS to boost SNR of reflected signals.3-unit PAVS is able to improve SNR by 6.53～9.54 dB based on theoretical analysis.Field seismic data were obtained for time delays 0,0.802,0.384,0.241,0.174,and 0.123 ms respectively.Using the raw data with different time delays,the power spectrums of reflected seismic signals were calculated,and then quantitative SNR improvement is obtained. Compared to the ease of single source,SNR increased by 3.3150,8.0150,6.0547,5.0278,4.5383,and 4.0364 dB,respectively.Compared to the case of combination source,SNR increased by 0, 4.7000,2.7397,1.7128,1.2233,and 0.7214 dB,respectively.On the basis of theoretical analysis and the results of field experiment,it concludes that directional seismic beam technique is useful to SNR improvement,SNR varies with time delay,proper time delay can raise SNR of reflected signals significantly.
引文
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[17] Morgan S P.Detection performance of a diffusive wave phased array.Applied Optics,2004,43(10) :2071～2078
[18] 姜弢,林君,陈祖斌等.相控震源对水平层状地下介质的高信噪比检测.仪器仪表学报,2006,27(11) :1369～1 372 Jiang T,Lin J,Chen Z B,et al.High signal-to noise ratio detection of horizontal layer underground medium with phased array vibroseis.Chinese Journal of Scientific Instrument (in Chinese),2006,27(11) :1369～1372．
[19] 林君,陈鹏程,姜 弢等.浅层地震探测的可控震源信号设计.地球物理学进展,2004,19(4) :807～811 Lin J,Chen P C,Jiang T,et al.The signal design of electrodynamic vibroseis for surface imaging.Progress in Geophysics (in Chinese),2004,19(4) :807～811
[20] 姜弢,林君,陈祖斌等.可控震源相控地震的相关检测技术.仪器仪表学报,2005,26(4) :336～339 Jiang T,Lin J,Chen Z B,et al.The correlation detection method of signals in phased array of vibroseis system.Chinese Journal of Scientific Instrument (in Chinese),2005,26(4) :336～339
[21] Jiang T,Lin J,Li T L,et al.Boosting signal to noise ratio of seismic signal using the phased-array vibrator system.Chinese J.Geophys.(in Chinese),2006,49(6) :1658～1664
[22] 姜弢,林君.相控震源与组合震源信号检测结果对比.控制与决策,2004,19(12) :1345～1348 Jiang T,Lin J.Comparison of the detected seismic signals between phased array and combination vibroseises.Kongzhi yu Juece/Controland Decision.(in Chinese),2004,19(12) :1345～1348,1353
[23] Tao Jiang,Jun Lin,Zhongren Wang,et al.Quantitative study on how phased-array vibrator system improves seismic signal resolution.The 2nd International Conference on Environmental and Engineering Geophysics,ICEEG2006, Wuhan,China,2006
[24] 姜弢,林君,杨冬等.相控震源定向地震波信号分析.地球物理学报,2008,51(5) :1551～1556 Jiang T,Lin J,Yang D,et al.Analysis of directional seismic signal based on phased-array vibrator system.Chinese J.Geophys.(in Chinese),2008,51(5) :1551～1556
[2] 葛洪魁,林建民,王宝善等.编码震源提高地震探测能力的野外实验研究,地球物理学报,2006,49(3) :864～870 Ge H K,Lin J M,Wang B S,et al.A field experiment study of improving the seismic detectability with coded source.Chinese J.Geophys.(in Chinese),2006,49(3) :864～870
[3] Arnold M E.Beam forming with vibrator arrays.Geophysics,1977,42(7) :1321～1338
[4] Yamaoka K,Watanabe T,Fujii N,et al.Monitoring Experiment in Tokai,Japan:ACROSS source designed for a phased array.American Geophysical Union,Fall Meeting 2005,abstract NG33B 0176,San Francisco,U.S.
[5] 姜弢,林君,陈祖斌等.相控震源地震波定向技术.吉林大学学报(信息科学版),2004,22(3) :181～184 Jiang T,Lin J,Chen Z B,et al.Seismic beam-forming in phased array of vibroseis.Journal of Jilin University (Information Science Edition) (in Chinese),2004,22 (3) :181～184
[6] 胡天跃,王润秋,White R E.地震资料处理中的聚束滤波方法.地球物理学报,2000,43(1) :105～115 Hu T Y,Wang R Q,White R E.Beamforming in seismic data processing.Chinese J.Geophys.(in Chinese),2000,43 (1) :105～115
[7] 洪菲,胡天跃,张文坡等.用优化聚束滤波方法消除低信噪比地震资料中的多次波.地球物理学报,2004,47(6) :1106～1110 Hong F,Hu T Y,Zhang W P,et al.Attenuating multiples for low signal-to noise ratio seismic data using optimal beamforming.Chinese J.Geophys.(in Chinese),2004,47 (6) :1106～1110
[8] Luo M Q,Cao J,Xie X B,et al.Comparison of illumination analyses using one-way and full-way propagators.Expanded Abstract of 74th Annual International SEG Meeting,2004． 67～70
[9] Xie X B,Jin S W,Wu R S.Wave equation based illumination analysis.Expanded Abstract of 74th Annual International SEG Meeting,2004． 933～936
[10] 陈生昌,马在田.广义地震数据合成及其偏移成像.地球物理学报,2006,49(4) :1144～1149 Chen S C,Ma Z T.Generalized synthesis of seismic data and its migration.Chinese J.Geophys.(in Chinese),2006,49 (4) :1144～1149
[11] 陈生昌,马在田,Wu Ru-Shan.波动方程偏移成像阴影的照明补偿.地球物理学报,2007,50(3) :844～850 Chen S C,Ma Z T,Wu R S.Illumination compensation for wave equation migration shadow.Chinese J.Geophys.(in Chinese),2007,50(3) :844～850
[12] Mosca S,Bilotti F,Toscano A,et al.A novel design method for Blass matrix beam-forming networks.IEEE Transactionsions on Antennas and Propagation,2002,50(2) :225～232
[13] Miura R,Tanaka T,Chiba I,et al.Beamforming e.xperiment with a DBF multibeam antenna in a mobile satellite environment.IEEE Transactions on Amennas and Propagation,1997,45(4) :707～714
[14] Kraft U R.Gain and G/T of multielement receive antennas with active beamforming networks.IEEE Transactions on Antennas and Propagation,2000,48(12) :1818～1829
[15] Denno S,Ohira T.Modified constant modulus algorithm for digital signal processing adaptive antennas with microwave analog beamforming.IEEE Transactions on Antennas and Propagation,2002,50 (6) :850～857
[16] Hatfield J V,Chai K S.A beam forming transmit ASIC for driving ultrasonic arrays.Sensors and Actuators,A:Physical,2001,92(1 3) :273～279
[17] Morgan S P.Detection performance of a diffusive wave phased array.Applied Optics,2004,43(10) :2071～2078
[18] 姜弢,林君,陈祖斌等.相控震源对水平层状地下介质的高信噪比检测.仪器仪表学报,2006,27(11) :1369～1 372 Jiang T,Lin J,Chen Z B,et al.High signal-to noise ratio detection of horizontal layer underground medium with phased array vibroseis.Chinese Journal of Scientific Instrument (in Chinese),2006,27(11) :1369～1372．
[19] 林君,陈鹏程,姜 弢等.浅层地震探测的可控震源信号设计.地球物理学进展,2004,19(4) :807～811 Lin J,Chen P C,Jiang T,et al.The signal design of electrodynamic vibroseis for surface imaging.Progress in Geophysics (in Chinese),2004,19(4) :807～811
[20] 姜弢,林君,陈祖斌等.可控震源相控地震的相关检测技术.仪器仪表学报,2005,26(4) :336～339 Jiang T,Lin J,Chen Z B,et al.The correlation detection method of signals in phased array of vibroseis system.Chinese Journal of Scientific Instrument (in Chinese),2005,26(4) :336～339
[21] Jiang T,Lin J,Li T L,et al.Boosting signal to noise ratio of seismic signal using the phased-array vibrator system.Chinese J.Geophys.(in Chinese),2006,49(6) :1658～1664
[22] 姜弢,林君.相控震源与组合震源信号检测结果对比.控制与决策,2004,19(12) :1345～1348 Jiang T,Lin J.Comparison of the detected seismic signals between phased array and combination vibroseises.Kongzhi yu Juece/Controland Decision.(in Chinese),2004,19(12) :1345～1348,1353
[23] Tao Jiang,Jun Lin,Zhongren Wang,et al.Quantitative study on how phased-array vibrator system improves seismic signal resolution.The 2nd International Conference on Environmental and Engineering Geophysics,ICEEG2006, Wuhan,China,2006
[24] 姜弢,林君,杨冬等.相控震源定向地震波信号分析.地球物理学报,2008,51(5) :1551～1556 Jiang T,Lin J,Yang D,et al.Analysis of directional seismic signal based on phased-array vibrator system.Chinese J.Geophys.(in Chinese),2008,51(5) :1551～1556
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