东海天然气水合物的地震特征
详细信息 本馆镜像全文    |  推荐本文 | | 获取馆网全文
摘要
使用中国科学院海洋研究所“科学一号”调查船于2001年以及20世纪80年代在东海地区采集的多道地震资料,以海域天然气水合物研究为目的,对这些资料进行了数据处理并获得了偏移地震剖面。通过对地震剖面的解释,在6条剖面上确定了6段异常反射为BSR,均有振幅强、与海底相位相反的特点。6段BSR基本上都没有出现和沉积地层相交的现象。分析认为,这与东海地区第四纪以来的沉积特征有关,并不能由此否认这些异常反射是BSR。6段BSR出现的水深为750~2 000 m,埋深在0.1~0.5 s(双程时间)之间。随着海底深度的增大,BSR埋深有增大的趋势。计算结果显示,6段BSR所处的温度和压力条件都满足水合物稳定赋存所需要的温度和压力条件。本文的BSR主要与北卡斯凯迪亚盆地以及智利海域水合物的温度、压力条件相似,而与日本南海海槽、美国布莱克海台等海域水合物的温度、压力条件相差比较大。在地震剖面上,6段BSR所处的局部构造位置都和挤压、断层有关,有利于水合物的发育;在空间上,它们主要分布在东海陆坡近槽底的位置以及与陆坡相近的槽底。在南北方向上,除分布在吐噶喇断裂和宫古断裂附近外,还与南奄西、伊平屋和八重山热液活动区相邻。热液活动和水合物虽然没有直接的成因关系,但岩浆活动为水合物气源的形成提供了热源条件,为流体和气体的运移、聚集提供了通道条件,从而有利于水合物的发育与赋存。根据地震剖面反射特征推断,剖面A1A2和A14A23发育BSR的位置应该有气体或者流体从海底流出,可能是海底冷泉发育的位置。剖面A14A23上BSR发育处,振幅比的异常增大和BSR埋深的降低是相关联的。这种关联支持该处发育海底冷泉的推测。
For the purpose of gas hydrate study,multi-channel seismic data were collected by Institute of Oceanology,Chinese Academy of Sciences(IOCAS) using "R/V Science 1" in the East China Sea in 2001.Seismic data from 2001 together with those from 1980s were processed to get the migration profiles.6 sections of abnormal reflections were determined as BSR based on the migration profiles interpretation.All the BSRs given have strong amplitude and reverse phase as comparing to the sea floor reflector and with buried depth within 0.1 to 0.5 seconds(two way travel time),which agrees with the data from published references.The buried depth of our BSRs increases with the increase of the sea floor depth from 750 m to around 2 000 m.There is no BSR that cuts the normal sediment layer as the case in other places,and this is because the upper Quaternary sediment layer in the East China Sea is parallel to the sea floor,leading the BSR to being parallel to the sea floor too.Thus it does not mean that our BSR is a faint one.The initial temperature and pressure calculation of our BSRs based on a very simple model for sediment velocity and temperature gradient shows that all our BSRs are within the stability domain in the gas hydrate phase diagram.Assuming that BSR is the base of gas hydrate stability zone in the gas hydrate phase diagram,our BSRs show a similar temperature and pressure condition to that of North Cascadia and Chilian Margin, but different from that of Nankai Trough and Blake Ridge.Among the whole Okinawa Trough,our BSR is either near main faults(Tokara fault and Miyako fault)or near hydrothermal activity fields distributed along the central graben of Okinawa Trough.On the seismic profile,our BSRs are locally related with tectonic compression and faulting,which can lead to the formation of gas hydrates.Although there is no direct relationship between hydrothermal activity and gas hydrate occurrence,shallow magma in hydrothermal field supplies heat for methane production from organic material in sediment and fault system in the hydrothermal area serves as conduits for the migration of methane from deeper part of the sediment to the gas hydrate reservoir.We believe that hydrothermal environment will help with the formation of gas hydrates.We can see from the seismic characteristics of profiles A1A2 and A14A23 that cold seepage occurs on the seafloor above the BSR of these two profiles.Coherence of the abnormal increase of amplitude ratio and the abnormal decrease of is considered as an evidence of cold seepage on profile A14A23 where BSR occurs.
引文
[1]Singh B C,Minshull T A,Spence G D.Velocity structure of agas hydrate reflector[J].Sicence,1993,260:204-207.
    [2]Kvenvolden K A.Gas hydrates—geologic perspective and glob-al change[J].Rev.Geophys.,1993,31:173-187.
    [3]DickensG R,Paull C K,Wallace P,et al.Direct measurementof in situ methane quantities in a large gas reservoir[J].Na-ture,1997,385:426-428.
    [4]Brewer P G,Orr F M,Friederich G,et al.Deep ocean fieldtest of methane hydrate formation from a remotely operatedvehicle[J].Geology,1997,25:407-410.
    [5]Paull C K,Borowski W S,Rodrigues N M,et al.Marine gashydrate inventory:preliminary results of ODP Leg 164 and im-plications for gas venting and slumping associated with theBlake Ridge gas hydrate field[M]//In:Henrient J P,MienertJ(eds).Gas hydrates:relevance to world margin stability andclimate change.Geol.Soc.London Spec.Publ.,1998,137:153-160.
    [6]宋海斌,松林修,吴能友,等.海洋天然气水合物的地球物理研究(I):岩石物性[J].地球物理学进展,2001,16(2):118-126.[SONG Hai-bin,Matsubayashi O,WU Neng-you,et al.Geo-physical researches on marine gas hydrates(I):physical prop-erties[J].Progress in Geophysics,2001,16(2):118-126.]
    [7]张光学,祝有海,徐华宁.非活动大陆边缘的天然气水合物及其成藏过程述评[J].地质论评,2003,49(2):181-186.[ZHANGGuang-xue,ZHU You-hai,XU Hua-ning.Gas hydrate on thepassive continental margin and its pool formation process[J].Geological Review,2003,49(2):181-186.]
    [8]Kvenvolden K A,Barnard L A.Gas hydrates of the Black Out-er Ridge.DSDP site 553,Leg76[R].Initial Reports of DeepSea Drilling Project 76,1983:353-366.
    [9]Kvenvolden K A.Subaquatic gas hydrate occurrence—modelsand settings[J].Eos,Trans,AGU,Spring Meeting,Suppl.,1993:74,369
    [10]Hyndman R D,Davis E E.A mechanism for the formation ofmethane hydrate and seafloor bottom simulating reflectors byvertical fluid expulsion[J].Journal Geophysical Research,1992,97:7 025-7 041.
    [11]Hyndman R D,Spence G D.A seismic study of methane hy-drate marine bottom simulating reflectors[J].Journal of Geo-physical Research,1992,97:6 683-6 698.
    [12]Dillon W P,Paul C K.Marine gas hydrates II,Geophysicalevidence[M]//In:Cox J L(ed).Natural gas hydrates:Prop-erties,Occurrences and Recovery.Butterworth,London,1983:73-90.
    [13]Miller J J,Lee M W,von Huene R.An analysis of a reflec-tion from the base of a gas hydrate zone off Peru[J].Am.Assoc.Pet.Geol.Bull.,1991,75:910-924.
    [14]Neben S,Hinz K,Beiersdorf H.Reflection characteristics,depth and geographical distribution of bottom simulating re-flectors within the accretionary wedge of Sulawesi[M]//In:Henriet J P,Mienert J(eds).Gas hydrates:relevance toworld margin stability and climate change.Geol Soc LondonSpec Publ.,1998,137:255-265.
    [15]宋海斌,张岭,江为为,等.海洋天然气水合物的地球物理研究(III):似海底反射[J].地球物理学进展,2003,18(2):183-187.[SONG Hai-bin,ZHANG Ling,JIANG Wei-wei,et al.Geophysical researches on marine gas hydrates(III):bottomsimulating reflector[J].Progress in Geophysics,2003,18(2):183-187.]
    [16]Lee M W,Hutchinson D R,Dillon W P,et al.Method of es-timating the amount of in situ gas hydrates in deep marinesediments[J].Mar.Petr.Geol.,1993,10:493-506.
    [17]Minshull T A,Singh B C,Westbrook G K.Seismic velocitystructure at a gas hydrate reflector,offshore western Colom-bia,from full waveform inversion[J].Journal of GeophysicalResearch,1994,99:4 715-4 734
    [18]秦蕴珊,赵一阳,陈丽蓉.东海地质[M].北京:科学出版社,1987.[QIN Yun-shan,ZHAO Yi-yang,CHEN Li-rong.EastChina Sea Geology[M].Beijing:Science Press,1987.]
    [19]许东禹.中国近海地质[M].北京:地震出版社,1997.[XUDong-yu.Offshore Geology of China Seas[M].Beijing:SeismPress,1997.]
    [20]刘光鼎.中国海区及邻域地质地球物理特征[M].北京:科学出版社,1992.[LIU Guang-ding.Geologic and GeophysicalFeatures of China Seas and Adjacent Regions[M].Beijing:Science Press,1992.]
    [21]金翔龙.东海海洋地质[M].北京:海洋出版社,1992.[JINXiang-long.Marine Geology of East China Sea[M].Beijing:China Ocean Press,1992.]
    [22]赵金海.东海中、新生代盆地成因机制和演化(上)[J].海洋石油,2004,24(4):6-14.[ZHAO Jin-hai.The forming factorsand evolvement of the Mesozoic and Cenozoic basin in theEast China Sea(I)[J].Offshore Oil,2004,24(4):6-14.]
    [23]赵金海.东海中、新生代盆地成因机制和演化(下)[J].海洋石油,2005,25(1):1-10.[ZHAO Jin-hai.The forming factorsand evolvement of the Mesozoic and Cenozoic basin in theEast China Sea(II)[J].Offshore Oil,2005,25(1):1-10.]
    [24]方银霞,金翔龙,杨树峰.冲绳海槽西北边坡天然气水合物的初步研究[J].海洋学报,2000,22(增刊):49-52.[FANG Yin-xia,JIN Xiang-long,YANG Shu-feng.Gas hydrate study ofthe northwest slope margin of the Okinawa Trough[J].ActaOceaniologica Sinica,2000,22(Sup.):49-52.]
    [25]孟宪伟,刘保华,石学法,等.冲绳海槽中段西陆坡下缘天然气水合物存在的可能性分析[J].沉积学报,2000,18(4):629-633.[MENG Xian-wei,LIU Bao-hua,SHI Xue-fa,et al.Thepossibility existence of gas hydrate in the lower slope marginof middle Okinawa Trough[J].Acta Sedimentologica Sinica,2000,18(4):629-633.]
    [26]栾锡武,初凤友,赵一阳,等.我国东海及邻近海域气体水合物可能的分布范围[J].沉积学报,2001,19(2):315-321[LUANXi-wu,CHU Feng-you,ZHAO Yi-yang et al.The possibledistribution of gas hydrate in the area of East China Sea andits vicinity[J].Acta Sedimentologica Sinica,2001,19(2):315-321.]
    [27]方银霞,黎明碧,金翔龙,等.东海冲绳海槽天然气水合物的形成条件[J].科技通报,2003,19(1):1-5.[FANG Yin-xia,LIMing-bi,JIN Xiang-long,et al.Formation condition of gashydrate in Okinawa Trough of East China Sea[J].Bulletin ofScience and Technology,2003,19(1):1-5.]
    [28]栾锡武,秦蕴珊,张训华,等.东海陆坡及相邻槽底天然气水合物的稳定域分析[J].地球物理学报,2003,46(4):467-475.[LUAN Xi-wu,QIN Yun-shan,ZHANG Xun-hua,et al.The stability zone of gas hydrate on the slope of the East Chi-na Sea and adjacent trough area[J].Chinese Journal of Geo-physics,2003,46(4):675-685.]
    [29]栾锡武,翟世奎,干晓群.冲绳海槽中部热液活动区构造地球物理特征分析[J].沉积学报,2001,19(1):43-48.[LUANXi-wu,ZHAI Shi-kui,GAN Xiao-qun.The characteristic oftectonophysics of the middle Okinawa Trough[J].Acta Sedi-mentologica Sinica,2001,19(1):43-48.]
    [30]栾锡武.现代海底热液活动区的分布与构造环境分析[J].地球科学进展,2004,19(6):931-938.[LUAN Xi-wu.Distribu-tion and tectonic environments of hydrothermal fields[J].Advance in Earth Science,2004,19(6):931-938.]
    [31]栾锡武.热液活动区数目与洋脊扩张速率的关系及其在冲绳海槽的应用[J].海洋地质与第四纪地质,2006,26(2):55-64.[LUAN Xi-wu.Relationship between the number of hydro-thermal activity fields and spreading rate and its application inthe Okinawa Trough[J].Marine Geology and QuaternaryGeology,2006,26(2):55-64.]
    [32]Lee C S.Exploration of submarine hydrothermal springs[M]//In:Liu K K,Liu C S,eds.Ocean and Taiwan in the21st Century,NCOR(National Center for Ocean Research).Taipei,2002.
    [33]Chow J,Lee J S,Sun R,et al.Characters of the bottom simu-lating reflectors near mud diapis:offshore southwestern Tai-wan[J].Geo-Marine Letters,2000,20:3-9.
    [34]Chi W C,Reed D L,Liu C S,et al.Distribution of the bottomsimulating reflector in the offshore Taiwan collision zone[J].TAO,1998,9(4):779-794.
    [35]栾锡武,张训华.东海及琉球沟弧盆体系热流测量及分布[J].地球物理学进展,2003,18(4):670-678.[LUAN Xi-wu,ZHANG Xun-hua.Heat flow measurement and distributionin the East China Sea and Ryukyu Trench Arc Back-Arc Sys-tem[J].Progress in Geophysics,2003,18(4):670-678.]
    [36]栾锡武,高德章,赵金海,等.东海及邻近海域一条剖面地壳速度结构[J].地球物理学进展,2001,16(2):28-35.[LUAN Xi-wu,GAO De-zhang,ZHAO Jin-hai,et al.The crust velocitystructure of a profile in the area of East China Sea and its vic-inity[J].Progress in Geophysics,2001,16(2):28-35.]
    [37]Hyndman R D,Spence G D,Chapman R,et al.Geophysicalstudies of marine gas hydrate in Northern Cascadia[J].GasHydrate in Northern Cascadia,2001:273-295.
    [38]Hamilton E L.Sound velocity-density relations in seafloor insediments and rocks[J].J.Acoust.Soc.Am.,1978,63:366.
    [39]Field M E,Kvenvolden K A.Gas hydrates on the northernCalifornia continental margin[J].Geology,1985,13:517-520.
    [40]Milkov A V,Claypool G E,Lee Y J,et al.In situ methaneconcentrations at Hydrate Ridge,offshore Oregon:New con-straints on the global gas hydrate inventory from an activemargin[J].Geology,2003,31(10):833-836.
    [41]Schwalenberg K,Willoughby E,Yuan J,et al.A controlledsource electromagnetic experiment for gas hydrate assess-ment:first results from the Chilean margin[J].AGU,SpringMeeting 2004,abstract#OS24A-06.
    [42]Miller J J,Lee M W,Huene R von.An analysis of a seismicreflection from the base of a gas hydrate zone,offshore Peru[J].AAPG Bull.,1982,66:789-792.
    [43]Netzeband G L,Hübscher C P,Gajewski D,et al.Seismic ve-locities from the Yaquina forearc basin off Peru:evidence forfree gas within the gas hydrate stability zone[J].InternationalJournal of Earth Sciences,2005,94(3):420-432.
    [44]NouzéH,Henry P,Noble M,et al.Large gas hydrate accu-mulations on the eastern Nankai Trough inferred from newhigh-resolution 2-D seismic data[J].Geophysical ResearchLetters,2004,31,doi:10.1029/2004GL019848
    [45]Collett T S,Ladd J.Detection of gas hydrate with downholelogs and assessment of gas hydrate contrations(staurations)and gas volumes on the Blake Ridge with electrical resistivitylog data[J].Proceedings of the Ocean Drilling Program,Sci-nentific Results,2000,164:179-191.
    [46]梁瑞才,吴金龙,刘保华,等.冲绳海槽中段线性磁条带异常及其构造发育[J].海洋学报,2001,23(2):69-78.[LIANG Rui-cai,WU Jin-long,LIU Bao-hua,et al.Tectonic and linearmagnetic anamaly of Middle Okinawa Trough[J].ActaOceanologica Sinica,2001,23(2):69-78.]
    [47]栾锡武,秦蕴珊.冲绳海槽宫古段西部槽底海底气泉的发现[J].科学通报,2005,50(8):801-810.[LUAN Xi-wu,QINYun-shan.Gas seepage on the sea floor of Okinawa TroughMiyako Section[J].Chinese Science Bulletin,2005,50(13):1 358-1 365.]

版权所有:© 2023 中国地质图书馆 中国地质调查局地学文献中心