海底地震仪的信号传递效果和噪声水平
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摘要
单球式海底地震仪(以下简称OBS)由于其成本低、操作简便的优点在天然地震研究、人工地震探测中获得了广泛应用.本文首先分析多型进口和国产OBS在台湾海峡西部采集的地震数据,发现同一台OBS上的垂直向速度检波器(Z分量)的信噪比常显著低于压力检波器(H分量),由于这两种检波器记录的都是海底的垂向振动信号,推测速度检波器的低信噪比更多的与仪器特性有关.然后从信号传递和噪声水平两方面分析影响速度检波器信噪比的因素:为检测速度检波器与OBS壳体的耦合效果,对某型宽频带OBS和陆上地震仪进行了同址同步观测试验,发现OBS的整机灵敏度有较大的差异;为分析速度检波器的水底噪声特征,以H分量记录作为基准,对比分析了同一台仪器不同站位的Z分量噪声水平,发现速度检波器在浅海区受到较大的次生干扰.本文指出OBS的内部耦合和水流次生干扰是至今尚未引起大家重视而又严重影响资料品质和多波探测成效的两个关键问题,这一研究结果对于改进OBS结构设计和制造工艺,以及OBS数据多分量处理方法研究有重要的参考意义.
Due to the features of low cost,small volume and easy to operate,single-sphere type OBSs are widely used in active and passive seismic observation.We check the OBS data in West Taiwan Strait and conclude that:Signal to Noise Ratio(SNR)of the hydrophone(H-component)usually greater than that of the vertical component geophone(Z-component)of the same OBS.Because the two types of detectors are designed to monitor the vertical movement of the seabed,we suggest that the significant difference between the two SNRs is related to the instrument characteristics.This paper makes analysis on the low SNR of Z-component by two ways:the signal transfer and the noise level.To determine the coupling of geophones and shell,we measure and analyze the seismograms of three broadband OBS in the same batch,together with two broadband land seismographs(CMG40-TDE)as a frame of reference.Our results show that there exist large variations of the internal damper not only between the OBSs,but also between the three components of the same OBS.Attempting to discern the cause of the noise levels,we analyze the noises recorded by the same OBS in 7 different sites.The results show that the geophones are sensitive to the secondary disturbances in shallow water zone.We pinpoint that the internal coupling and the secondary water disturbances significantly affect the data quality of OBS and the outcome of multi-component exploration,which did not get deserved concern before.This study proposes an important developing direction for the architecture design and manufacturing technology of OBS,and provides a good reference for the multi-component seismic processing of OBS data.
Due to the features of low cost,small volume and easy to operate,single-sphere type OBSs are widely used in active and passive seismic observation.We check the OBS data in West Taiwan Strait and conclude that:Signal to Noise Ratio(SNR)of the hydrophone(H-component)usually greater than that of the vertical component geophone(Z-component)of the same OBS.Because the two types of detectors are designed to monitor the vertical movement of the seabed,we suggest that the significant difference between the two SNRs is related to the instrument characteristics.This paper makes analysis on the low SNR of Z-component by two ways:the signal transfer and the noise level.To determine the coupling of geophones and shell,we measure and analyze the seismograms of three broadband OBS in the same batch,together with two broadband land seismographs(CMG40-TDE)as a frame of reference.Our results show that there exist large variations of the internal damper not only between the OBSs,but also between the three components of the same OBS.Attempting to discern the cause of the noise levels,we analyze the noises recorded by the same OBS in 7 different sites.The results show that the geophones are sensitive to the secondary disturbances in shallow water zone.We pinpoint that the internal coupling and the secondary water disturbances significantly affect the data quality of OBS and the outcome of multi-component exploration,which did not get deserved concern before.This study proposes an important developing direction for the architecture design and manufacturing technology of OBS,and provides a good reference for the multi-component seismic processing of OBS data.
引文
Chabert A,Minshull T A,Westbrook G K,et al.2011.Characterization of a stratigraphically constrained gas hydrate system along the western continental margin of Svalbard from ocean bottom seismometer data.Journal of Geophysical Research:Solid Earth,116(B12):1978-2012,B12102,doi:10.1029/2011JB008211.
Chen G X,Tian G.2016.Geophone-media coupling system based on elastic wave dynamics.Geophysical Prospecting for Petroleum(in Chinese),55(3):333-340.
Chen Y N,Gung Y,You S H,et al.2011.Characteristics of short period secondary microseisms(SPSM)in Taiwan:The influence of shallow ocean strait on SPSM.Geophysical Research Letters,38(4):155-170,L04305,doi:10.1029/2010GL046290.
Crawford W C.2000.Identifying and removing tilt noise from lowfrequency(<0.1Hz)seafloor vertical seismic data.Bulletin of the Seismological Society of America,90(4):952-963.
Cui P,Wang J H,Li B.2010.Research of design method for ocean bottom seismometer based on the coupling theory.Ship Science and Technology(in Chinese),32(4):89-92.
Duennebier F K,Sutton G H.1995.Fidelity of ocean bottom seismic observations.Marine Geophysical Researches,17(6):535-555.
Eguchi T,Fujinawa Y,Matsuzaki T,et al.1986.New pop-up type Ocean Bottom Seismometer.Marine Geophysical Researches,8(2):187-199.
Exley R J K,Westbrook G K,Haacke R R,et al.2010.Detection of seismic anisotropy using ocean bottom seismometers:a case study from the northern headwall of the Storegga Slide.Geophysical Journal International,183(1):188-210.
Hao T Y,You Q Y.2011.Progress of homemade OBS and its application on ocean bottom structure survey.Chinese Journal of Geophysics(in Chinese),54(12):3352-3361,doi:10.3969/j.issn.0001-5733.2011.12.033.
Hao X Z,Wu Z L,Wang W W,et al.2015.Performance test of high-frequency ocean bottom seismometer.Journal of Tropical Oceanography(in Chinese),34(4):54-58.
Hu H,Ruan A G,You Q Y,et al.2016.Using OBS teleseismic receiver functions to invert lithospheric structure-a case study of the southwestern subbasin in the South China Sea.Chinese Journal of Geophysics(in Chinese),59(4):1426-1434,doi:10.6038/cjg20160423.
Huang Z Y,Tan D L,Xu Y M,et al.2005.Vector-fidelity analysis of multi-components data.Geophysical Prospecting for Petroleum(in Chinese).44(3):206-208.
Laske G,Collins J A,Wolfe C J,et al.2009.Probing the Hawaiian hot spot with new Broadband Ocean Bottom instruments.Eos,Transactions American Geophysical Union,90(41):362-363,doi:10.1029/2009EO410002.
Li Q Z.1993.The Way to Obtain A Better Resolution in Seismic Prospecting-A Systematical Analysis of High Resolution Seismic Exploration.Beijing:Petroleum Industry Press.
Lindholm C D,Marrow P C.1990.Ocean bottom seismometers in the northern North Sea:Experience and preliminary results with the Statfjord OBS.Bulletin of the Seismological Society of America,80(4):1014-1025.
Liu C G,Hua Q F,Pei Y L,et al.2014.Passive-source Ocean Bottom Seismograph(OBS)array experiment in South China Sea and data quality analyses.Chinese Science Bulletin,59(33):4524-4536.
Mànuel A,Roset X,Del Rio J,et al.2012.Ocean bottom seismometer:design and test of a measurement system for marine seismology.Sensors,12(3):3693-3719.
Menke W,Levin V,Webb S.2005.Receiver function analysis of OBS data:possibilities and drawbacks.∥AGU Fall Meeting Abstracts.San Francisco:American Geophysical Union.
Niu X W,Gao J Y,Wu Z C,et al.2016.Lithosphere Anisotropy of Prydz Bay,Antarctica:from ocean bottom seismometer long term observation.Earth Science(in Chinese),41(11):1950-1958.
Prothero W A Jr.1979.An operationally optimized ocean-bottom seismometer capsule.Physics of the Earth and Planetary Interiors,18(2):71-77.
Prothero W A Jr.1984.Ocean bottom seismometer technology.Eos,Transactions American Geophysical Union,65(13):113-116.
Qiu X L,Zhao M H,Ye C M,et al.2003.Ocean bottom seismometer and onshore-offshore seismic experiment in northeastern South China Sea.Geotectonica et Metallogenia(in Chinese),27(4):295-300.
Rodriguez I,Manuel-Lazaro A,Carlosena A,et al.2006.Signal processing in ocean bottom seismographs for refraction seismology.IEEE Transactions on Instrumentation and Measurement,55(2):652-658.
Ruan A G,Li J B,Feng Z Y,et al.2004.Ocean bottom seismometer and its development in the world.Donghai Marine Science(in Chinese),22(2):19-27.
Ruan A G,Li J B,Chen Y S,et al.2010.The experiment of broad band I-4Ctype OBS in the Southwest India ridge.Chinese Journal of Geophysics(in Chinese),53(4):1015-1018,doi:10.3969/j.issn.0001-5733.2010.04.026.
Si S K,Liu B H,Liu C G,et al.2017.SKS splitting measurements with unknown horizontal orientation of the ocean bottom seismograph.Chinese Journal of Geophysics(in Chinese),60(3):999-1006,doi:10.6038/cjg20170314.
Sun C Y.1993.A discussion of the geophone-ground coupling.Petroleum Instruments(in Chinese),7(4):217-221.
Sutton G H,Duennebier F K,Iwatake B.1981.Coupling of ocean bottom seismometers to soft bottom.Marine Geophysical Researches,5(1):35-51.
Sutton G H,Duennebier F K.1987.Optimum design of ocean bottom seismometers.Marine Geophysical Researches,9(1):47-65.
Trehu A M,Solomon S C.1981.Coupling parameters of the MITOBS at two nearshore sites.Marine Geophysical Researches,5(1):69-78.
Wang Q,Qiu X L,Zhao M H,et al.2016.Analysis and processing on abnormal OBS data in the South China Sea.Chinese Journal of Geophysics(in Chinese),59(3):1102-1112,doi:10.6038/cjg20160330.
Wang S,Qiu X L,Fang W H,et al.2018.Features of the onshoreoffshore seismic data in Southwest Taiwan Strait and some countermeasures for data processing.Journal of Tropical Oceanography(in Chinese),37(2):92-99.
Webb S C.1998.Broadband seismology and noise under the ocean.Reviews of Geophysics,36(1):105-142.
Xu W W,Yuan S Y,Ai Y S,et al.2017.Applying multiple channel correlation technique in the self-noise measurement of broadband seismographs.Chinese Journal of Geophysics(in Chinese),60(9):3466-3474,doi:10.6038/cjg20170916.
Yu F W,Wei J D,Feng Y P,et al.2016.A quantitative analysis method for geophone coupling effects.Oil Geophysical Prospecting(in Chinese),51(1):27-31.
Zelikovitz S J,Prothero W A Jr.1981.The vertical response of an ocean bottom seismometer:analysis of the lopez island vertical transient tests.Marine Geophysical Researches,5(1):53-67.
Zhao W N,Zhang X H,Meng X J,et al.2017.Analysis of converted shear-waves based on OBS data in the South YellowSea and its geological implications.Chinese Journal of Geophysics(in Chinese),60(4):1479-1490,doi:10.6038/cjg20170421.
陈高翔,田钢.2016.基于弹性波动力学的检波器-介质耦合系统研究.石油物探,55(3):333-340.
崔培,王纪会,李彪.2010.基于耦合理论的海底地震仪设计方法研究.舰船科学技术,32(4):89-92.
郝天珧,游庆瑜.2011.国产海底地震仪研制现状及其在海底结构探测中的应用.地球物理学报,54(12):3352-3361,doi:10.3969/j.issn.0001-5733.2011.12.033.
郝小柱,伍忠良,王伟巍等.2015.高频海底地震仪性能检测.热带海洋学报,34(4):54-58.
胡昊,阮爱国,游庆瑜等.2016.海底地震仪远震记录接收函数反演---以南海西南次海盆为例.地球物理学报,59(4):1426-1434,doi:10.6038/cjg20160423.
黄中玉,谈大龙,徐亦鸣等.2005.多分量地震数据矢量保真度分析.石油物探,44(3):206-208.
李庆忠.1993.走向精确勘探的道路---高分辨率地震勘探系统工程剖析.北京:石油工业出版社.
刘晨光,华清峰,裴彦良等.2014.南海海底天然地震台阵观测实验及其数据质量分析.科学通报,59(16):1542-1552.
牛雄伟,高金耀,吴招才等.2016.南极洲普里兹湾岩石圈各向异性---海底地震仪观测.地球科学,41(11):1950-1958.
丘学林,赵明辉,叶春明等.2003.南海东北部海陆联测与海底地震仪探测.大地构造与成矿学,27(4):295-300.
阮爱国,李家彪,冯占英等.2004.海底地震仪及其国内外发展现状.东海海洋,22(2):19-27.
阮爱国,李家彪,陈永顺等.2010.国产I-4C型OBS在西南印度洋中脊的试验.地球物理学报,53(4):1015-1018,doi:10.3969/j.issn.0001-5733.2010.04.026.
司少坤,刘保华,刘晨光等.2017.未知OBS水平方位的SKS分裂参数测量.地球物理学报,60(3):999-1006,doi:10.6038/cjg20170314.
孙传友.1993.检波器与地面耦合问题探讨.石油仪器,7(4):217-221.
王强,丘学林,赵明辉等.2016.南海海底地震仪异常数据的分析和处理.地球物理学报,59(3):1102-1112,doi:10.6038/cjg20160330.
王笋,丘学林,方伟华等.2018.台湾海峡西南部的海陆联合深地震探测资料特点与处理对策.热带海洋学报,37(2):92-99.
许卫卫,袁松湧,艾印双等.2017.多通道相关分析用于宽频带地震仪自噪声检测.地球物理学报,60(9):3466-3474,doi:10.6038/cjg20170916.
于富文,魏继东,冯玉苹等.2016.检波器耦合响应定量分析方法及应用.石油地球物理勘探,51(1):27-31.
赵维娜,张训华,孟祥君等.2017.南黄海OBS数据转换横波分析及其地质意义.地球物理学报,60(4):1479-1490,doi:10.6038/cjg20170421.
Chen G X,Tian G.2016.Geophone-media coupling system based on elastic wave dynamics.Geophysical Prospecting for Petroleum(in Chinese),55(3):333-340.
Chen Y N,Gung Y,You S H,et al.2011.Characteristics of short period secondary microseisms(SPSM)in Taiwan:The influence of shallow ocean strait on SPSM.Geophysical Research Letters,38(4):155-170,L04305,doi:10.1029/2010GL046290.
Crawford W C.2000.Identifying and removing tilt noise from lowfrequency(<0.1Hz)seafloor vertical seismic data.Bulletin of the Seismological Society of America,90(4):952-963.
Cui P,Wang J H,Li B.2010.Research of design method for ocean bottom seismometer based on the coupling theory.Ship Science and Technology(in Chinese),32(4):89-92.
Duennebier F K,Sutton G H.1995.Fidelity of ocean bottom seismic observations.Marine Geophysical Researches,17(6):535-555.
Eguchi T,Fujinawa Y,Matsuzaki T,et al.1986.New pop-up type Ocean Bottom Seismometer.Marine Geophysical Researches,8(2):187-199.
Exley R J K,Westbrook G K,Haacke R R,et al.2010.Detection of seismic anisotropy using ocean bottom seismometers:a case study from the northern headwall of the Storegga Slide.Geophysical Journal International,183(1):188-210.
Hao T Y,You Q Y.2011.Progress of homemade OBS and its application on ocean bottom structure survey.Chinese Journal of Geophysics(in Chinese),54(12):3352-3361,doi:10.3969/j.issn.0001-5733.2011.12.033.
Hao X Z,Wu Z L,Wang W W,et al.2015.Performance test of high-frequency ocean bottom seismometer.Journal of Tropical Oceanography(in Chinese),34(4):54-58.
Hu H,Ruan A G,You Q Y,et al.2016.Using OBS teleseismic receiver functions to invert lithospheric structure-a case study of the southwestern subbasin in the South China Sea.Chinese Journal of Geophysics(in Chinese),59(4):1426-1434,doi:10.6038/cjg20160423.
Huang Z Y,Tan D L,Xu Y M,et al.2005.Vector-fidelity analysis of multi-components data.Geophysical Prospecting for Petroleum(in Chinese).44(3):206-208.
Laske G,Collins J A,Wolfe C J,et al.2009.Probing the Hawaiian hot spot with new Broadband Ocean Bottom instruments.Eos,Transactions American Geophysical Union,90(41):362-363,doi:10.1029/2009EO410002.
Li Q Z.1993.The Way to Obtain A Better Resolution in Seismic Prospecting-A Systematical Analysis of High Resolution Seismic Exploration.Beijing:Petroleum Industry Press.
Lindholm C D,Marrow P C.1990.Ocean bottom seismometers in the northern North Sea:Experience and preliminary results with the Statfjord OBS.Bulletin of the Seismological Society of America,80(4):1014-1025.
Liu C G,Hua Q F,Pei Y L,et al.2014.Passive-source Ocean Bottom Seismograph(OBS)array experiment in South China Sea and data quality analyses.Chinese Science Bulletin,59(33):4524-4536.
Mànuel A,Roset X,Del Rio J,et al.2012.Ocean bottom seismometer:design and test of a measurement system for marine seismology.Sensors,12(3):3693-3719.
Menke W,Levin V,Webb S.2005.Receiver function analysis of OBS data:possibilities and drawbacks.∥AGU Fall Meeting Abstracts.San Francisco:American Geophysical Union.
Niu X W,Gao J Y,Wu Z C,et al.2016.Lithosphere Anisotropy of Prydz Bay,Antarctica:from ocean bottom seismometer long term observation.Earth Science(in Chinese),41(11):1950-1958.
Prothero W A Jr.1979.An operationally optimized ocean-bottom seismometer capsule.Physics of the Earth and Planetary Interiors,18(2):71-77.
Prothero W A Jr.1984.Ocean bottom seismometer technology.Eos,Transactions American Geophysical Union,65(13):113-116.
Qiu X L,Zhao M H,Ye C M,et al.2003.Ocean bottom seismometer and onshore-offshore seismic experiment in northeastern South China Sea.Geotectonica et Metallogenia(in Chinese),27(4):295-300.
Rodriguez I,Manuel-Lazaro A,Carlosena A,et al.2006.Signal processing in ocean bottom seismographs for refraction seismology.IEEE Transactions on Instrumentation and Measurement,55(2):652-658.
Ruan A G,Li J B,Feng Z Y,et al.2004.Ocean bottom seismometer and its development in the world.Donghai Marine Science(in Chinese),22(2):19-27.
Ruan A G,Li J B,Chen Y S,et al.2010.The experiment of broad band I-4Ctype OBS in the Southwest India ridge.Chinese Journal of Geophysics(in Chinese),53(4):1015-1018,doi:10.3969/j.issn.0001-5733.2010.04.026.
Si S K,Liu B H,Liu C G,et al.2017.SKS splitting measurements with unknown horizontal orientation of the ocean bottom seismograph.Chinese Journal of Geophysics(in Chinese),60(3):999-1006,doi:10.6038/cjg20170314.
Sun C Y.1993.A discussion of the geophone-ground coupling.Petroleum Instruments(in Chinese),7(4):217-221.
Sutton G H,Duennebier F K,Iwatake B.1981.Coupling of ocean bottom seismometers to soft bottom.Marine Geophysical Researches,5(1):35-51.
Sutton G H,Duennebier F K.1987.Optimum design of ocean bottom seismometers.Marine Geophysical Researches,9(1):47-65.
Trehu A M,Solomon S C.1981.Coupling parameters of the MITOBS at two nearshore sites.Marine Geophysical Researches,5(1):69-78.
Wang Q,Qiu X L,Zhao M H,et al.2016.Analysis and processing on abnormal OBS data in the South China Sea.Chinese Journal of Geophysics(in Chinese),59(3):1102-1112,doi:10.6038/cjg20160330.
Wang S,Qiu X L,Fang W H,et al.2018.Features of the onshoreoffshore seismic data in Southwest Taiwan Strait and some countermeasures for data processing.Journal of Tropical Oceanography(in Chinese),37(2):92-99.
Webb S C.1998.Broadband seismology and noise under the ocean.Reviews of Geophysics,36(1):105-142.
Xu W W,Yuan S Y,Ai Y S,et al.2017.Applying multiple channel correlation technique in the self-noise measurement of broadband seismographs.Chinese Journal of Geophysics(in Chinese),60(9):3466-3474,doi:10.6038/cjg20170916.
Yu F W,Wei J D,Feng Y P,et al.2016.A quantitative analysis method for geophone coupling effects.Oil Geophysical Prospecting(in Chinese),51(1):27-31.
Zelikovitz S J,Prothero W A Jr.1981.The vertical response of an ocean bottom seismometer:analysis of the lopez island vertical transient tests.Marine Geophysical Researches,5(1):53-67.
Zhao W N,Zhang X H,Meng X J,et al.2017.Analysis of converted shear-waves based on OBS data in the South YellowSea and its geological implications.Chinese Journal of Geophysics(in Chinese),60(4):1479-1490,doi:10.6038/cjg20170421.
陈高翔,田钢.2016.基于弹性波动力学的检波器-介质耦合系统研究.石油物探,55(3):333-340.
崔培,王纪会,李彪.2010.基于耦合理论的海底地震仪设计方法研究.舰船科学技术,32(4):89-92.
郝天珧,游庆瑜.2011.国产海底地震仪研制现状及其在海底结构探测中的应用.地球物理学报,54(12):3352-3361,doi:10.3969/j.issn.0001-5733.2011.12.033.
郝小柱,伍忠良,王伟巍等.2015.高频海底地震仪性能检测.热带海洋学报,34(4):54-58.
胡昊,阮爱国,游庆瑜等.2016.海底地震仪远震记录接收函数反演---以南海西南次海盆为例.地球物理学报,59(4):1426-1434,doi:10.6038/cjg20160423.
黄中玉,谈大龙,徐亦鸣等.2005.多分量地震数据矢量保真度分析.石油物探,44(3):206-208.
李庆忠.1993.走向精确勘探的道路---高分辨率地震勘探系统工程剖析.北京:石油工业出版社.
刘晨光,华清峰,裴彦良等.2014.南海海底天然地震台阵观测实验及其数据质量分析.科学通报,59(16):1542-1552.
牛雄伟,高金耀,吴招才等.2016.南极洲普里兹湾岩石圈各向异性---海底地震仪观测.地球科学,41(11):1950-1958.
丘学林,赵明辉,叶春明等.2003.南海东北部海陆联测与海底地震仪探测.大地构造与成矿学,27(4):295-300.
阮爱国,李家彪,冯占英等.2004.海底地震仪及其国内外发展现状.东海海洋,22(2):19-27.
阮爱国,李家彪,陈永顺等.2010.国产I-4C型OBS在西南印度洋中脊的试验.地球物理学报,53(4):1015-1018,doi:10.3969/j.issn.0001-5733.2010.04.026.
司少坤,刘保华,刘晨光等.2017.未知OBS水平方位的SKS分裂参数测量.地球物理学报,60(3):999-1006,doi:10.6038/cjg20170314.
孙传友.1993.检波器与地面耦合问题探讨.石油仪器,7(4):217-221.
王强,丘学林,赵明辉等.2016.南海海底地震仪异常数据的分析和处理.地球物理学报,59(3):1102-1112,doi:10.6038/cjg20160330.
王笋,丘学林,方伟华等.2018.台湾海峡西南部的海陆联合深地震探测资料特点与处理对策.热带海洋学报,37(2):92-99.
许卫卫,袁松湧,艾印双等.2017.多通道相关分析用于宽频带地震仪自噪声检测.地球物理学报,60(9):3466-3474,doi:10.6038/cjg20170916.
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