SEISMIC CHARACTERISTICS OF GAS HYDRATES IN THE EAST CHINA SEA

LUAN Xi-wu; YUE Bao-jing; LU Yin-tao

2006 Vol. 26, No. 5

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Article navigation > Marine Geology & Quaternary Geology > 2006 > 26(5): 91-99

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LUAN Xi-wu, YUE Bao-jing, LU Yin-tao. SEISMIC CHARACTERISTICS OF GAS HYDRATES IN THE EAST CHINA SEA[J]. Marine Geology & Quaternary Geology, 2006, 26(5): 91-99.

Citation:

LUAN Xi-wu, YUE Bao-jing, LU Yin-tao. SEISMIC CHARACTERISTICS OF GAS HYDRATES IN THE EAST CHINA SEA[J]. Marine Geology & Quaternary Geology, 2006, 26(5): 91-99.

SEISMIC CHARACTERISTICS OF GAS HYDRATES IN THE EAST CHINA SEA

Institute of Oceanology, Chinese Academy of Sciences, Qingdao 266071, China

Received Date: 01 March 2006

Revised Date: 08 June 2006

Abstract

Abstract

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.
- gas hydrate /
- seismic reflection /
- BSR /
- cold seepage /
- East China Sea

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References

[1]	Singh B C, Minshull T A, Spence G D. Velocity structure of a gas hydrate reflector[J]. Sicence, 1993,260:204-207. Google Scholar
[2]	Kvenvolden K A.Gas hydrates-geologic perspective and global change[J].Rev. Geophys., 1993,31:173-187. Google Scholar
[3]	Dickens G R, Paull C K, Wallace P, et al.Direct measurement of in situ methane quantities in a large gas reservoir[J]. Nature, 1997, 385:426-428. Google Scholar
[4]	Brewer P G, Orr F M, Friederich G,et al.Deep ocean field test of methane hydrate formation from a remotely operated vehicle[J]. Geology, 1997, 25:407-410. Google Scholar
[5]	Paull C K, Borowski W S, Rodrigues N M,et al.Marine gas hydrate inventory:preliminary results of ODP Leg 164 and implications for gas venting and slumping associated with the Blake Ridge gas hydrate field[M]//In:Henrient J P, Mienert J (eds). Gas hydrates:relevance to world margin stability and climate change. Geol.Soc.London Spec.Publ., 1998, 137:153-160. Google Scholar
[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. Google Scholar [SONG Hai-bin, Matsubayashi O, WU Neng-you,et al.Geophysical researches on marine gas hydrates (I):physical properties[J]. Progress in Geophysics, 2001, 16(2):118-126.] Google Scholar
[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. Google Scholar [ZHANG Guang-xue, ZHU You-hai,XU Hua-ning. Gas hydrate on the passive continental margin and its pool formation process[J]. Geological Review, 2003, 49(2):181-186.] Google Scholar
[8]	Kvenvolden K A, Barnard L A.Gas hydrates of the Black Outer Ridge. DSDP site 553, Leg76[R]. Initial Reports of Deep Sea Drilling Project 76,1983:353-366. Google Scholar
[9]	Kvenvolden K A.Subaquatic gas hydrate occurrence-models and settings[J]. Eos,Trans, AGU, Spring Meeting, Suppl.,1993:74, 369 Google Scholar
[10]	Hyndman R D, Davis E E. A mechanism for the formation of methane hydrate and seafloor bottom simulating reflectors by vertical fluid expulsion[J]. Journal Geophysical Research, 1992, 97:7025-7041. Google Scholar
[11]	Hyndman R D, Spence G D. A seismic study of methane hydrate marine bottom simulating reflectors[J]. Journal of Geophysical Research, 1992, 97:6683-6698. Google Scholar
[12]	Dillon W P, Paul C K. Marine gas hydrates Ⅱ, Geophysical evidence[M]//In:Cox J L(ed).Natural gas hydrates:Properties, Occurrences and Recovery. Butterworth, London, 1983:73-90. Google Scholar
[13]	Miller J J, Lee M W, von Huene R. An analysis of a reflection from the base of a gas hydrate zone off Peru[J]. Am. Assoc. Pet. Geol. Bull.,1991, 75:910-924. Google Scholar
[14]	Neben S, Hinz K, Beiersdorf H. Reflection characteristics, depth and geographical distribution of bottom simulating reflectors within the accretionary wedge of Sulawesi[M]//In:Henriet J P, Mienert J (eds).Gas hydrates:relevance to world margin stability and climate change. Geol Soc London Spec Publ., 1998,137:255-265. Google Scholar
[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. Google Scholar [SONG Hai-bin, ZHANG Ling, JIANG Wei-wei,et al. Geophysical researches on marine gas hydrates (Ⅲ):bottom simulating reflector[J]. Progress in Geophysics, 2003, 18(2):183-187.] Google Scholar
[16]	Lee M W, Hutchinson D R, Dillon W P,et al.Method of estimating the amount of in situ gas hydrates in deep marine sediments[J]. Mar. Petr. Geol.,1993, 10:493-506. Google Scholar
[17]	Minshull T A, Singh B C, Westbrook G K. Seismic velocity structure at a gas hydrate reflector, offshore western Colombia, from full waveform inversion[J]. Journal of Geophysical Research, 1994, 99:4715-4734 Google Scholar
[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.East China Sea Geology[M].Beijing:Science Press,1987.] Google Scholar
[19]	许东禹.中国近海地质[M].北京:地震出版社,1997.[XU Dong-yu.Offshore Geology of China Seas[M].Beijing:Seism Press,1997.] Google Scholar
[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 Geophysical Features of China Seas and Adjacent Regions[M].Beijing:Science Press,1992.] Google Scholar
[21]	金翔龙.东海海洋地质[M].北京:海洋出版社,1992.[JIN Xiang-long.Marine Geology of East China Sea[M].Beijing:China Ocean Press,1992.] Google Scholar
[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. Google Scholar [ZHAO Jin-hai.The forming factors and evolvement of the Mesozoic and Cenozoic basin in the East China Sea(I)[J]. Offshore Oil, 2004, 24(4):6-14.] Google Scholar
[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. Google Scholar [ZHAO Jin-hai.The forming factors and evolvement of the Mesozoic and Cenozoic basin in the East China Sea(Ⅱ)[J]. Offshore Oil, 2005, 25(1):1-10.] Google Scholar
[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 of the northwest slope margin of the Okinawa Trough[J].Acta Oceaniologica Sinica,2000 Google Scholar ,22(Sup.):49-52.] Google Scholar
[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. Google Scholar [MENG Xian-wei,LIU Bao-hua,SHI Xue-fa,et al.The possibility existence of gas hydrate in the lower slope margin of middle Okinawa Trough[J].Acta Sedimentologica Sinica,2000,18(4):629-633.] Google Scholar
[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 Google Scholar [LUAN Xi-wu,CHU Feng-you,ZHAO Yi-yang et al.The possible distribution of gas hydrate in the area of East China Sea and its vicinity[J].Acta Sedimentologica Sinica,2001,19(2):315-321.] Google Scholar
[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. Google Scholar [FANG Yin-xia, LI Ming-bi, JIN Xiang-long,et al. Formation condition of gas hydrate in Okinawa Trough of East China Sea[J]. Bulletin of Science and Technology, 2003, 19(1):1-5.] Google Scholar
[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. Google Scholar [LUAN Xi-wu, QIN Yun-shan, ZHANG Xun-hua, et al. The stability zone of gas hydrate on the slope of the East China Sea and adjacent trough area[J]. Chinese Journal of Geophysics, 2003, 46(4):675-685.] Google Scholar
[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. Google Scholar [LUAN Xi-wu,ZHAI Shi-kui, GAN Xiao-qun. The characteristic of tectonophysics of the middle Okinawa Trough[J]. Acta Sedimentologica Sinica, 2001, 19(1):43-48.] Google Scholar
[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. Google Scholar [LUAN Xi-wu. Distribution and tectonic environments of hydrothermal fields[J]. Advance in Earth Science, 2004, 19(6):931-938.] Google Scholar
[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. Google Scholar [LUAN Xi-wu. Relationship between the number of hydrothermal activity fields and spreading rate and its application in the Okinawa Trough[J]. Marine Geology and Quaternary Geology, 2006, 26(2):55-64.] Google Scholar
[32]	Lee C S.Exploration of submarine hydrothermal springs[M]//In:Liu K K,Liu C S, eds. Ocean and Taiwan in the 21st Century, NCOR (National Center for Ocean Research). Taipei,2002. Google Scholar
[33]	Chow J,Lee J S,Sun R,et al.Characters of the bottom simulating reflectors near mud diapis:offshore southwestern Taiwan[J].Geo-Marine Letters,2000,20:3-9. Google Scholar
[34]	Chi W C,Reed D L,Liu C S,et al. Distribution of the bottom simulating reflector in the offshore Taiwan collision zone[J]. TAO, 1998, 9(4):779-794. Google Scholar
[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. Google Scholar [LUAN Xi-wu, ZHANG Xun-hua. Heat flow measurement and distribution in the East China Sea and Ryukyu Trench Arc Back-Arc System[J]. Progress in Geophysics, 2003, 18(4):670-678.] Google Scholar
[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. Google Scholar [LUAN Xi-wu,GAO De-zhang,ZHAO Jin-hai,et al.The crust velocity structure of a profile in the area of East China Sea and its vicinity[J].Progress in Geophysics,2001,16(2):28-35.] Google Scholar
[37]	Hyndman R D, Spence G D, Chapman R,et al.Geophysical studies of marine gas hydrate in Northern Cascadia[J]. Gas Hydrate in Northern Cascadia, 2001:273-295. Google Scholar
[38]	Hamilton E L. Sound velocity-density relations in seafloor in sediments and rocks[J]. J. Acoust. Soc. Am.,1978, 63:366. Google Scholar
[39]	Field M E,Kvenvolden K A.Gas hydrates on the northern California continental margin[J].Geology,1985,13:517-520. Google Scholar
[40]	Milkov A V,Claypool G E,Lee Y J,et al.In situ methane concentrations at Hydrate Ridge,offshore Oregon:New constraints on the global gas hydrate inventory from an active margin[J].Geology,2003,31(10):833-836. Google Scholar
[41]	Schwalenberg K,Willoughby E,Yuan J,et al.A controlled source electromagnetic experiment for gas hydrate assessment:first results from the Chilean margin[J].AGU,Spring Meeting 2004,abstract #OS24A-06. Google Scholar
[42]	Miller J J,Lee M W,Huene R von. An analysis of a seismic reflection from the base of a gas hydrate zone,offshore Peru[J].AAPG Bull.,1982,66:789-792. Google Scholar
[43]	Netzeband G L,Hübscher C P,Gajewski D,et al.Seismic velocities from the Yaquina forearc basin off Peru:evidence for free gas within the gas hydrate stability zone[J].International Journal of Earth Sciences,2005,94(3):420-432. Google Scholar
[44]	Nouzé H,Henry P,Noble M,et al.Large gas hydrate accumulations on the eastern Nankai Trough inferred from new high-resolution 2-D seismic data[J].Geophysical Research Letters,2004,31,doi:10.1029/2004GL019848 Google Scholar
[45]	Collett T S,Ladd J.Detection of gas hydrate with downhole logs and assessment of gas hydrate contrations(staurations)and gas volumes on the Blake Ridge with electrical resistivity log data[J]. Proceedings of the Ocean Drilling Program,Scinentific Results,2000,164:179-191. Google Scholar
[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. Google Scholar [LIANG Rui-cai, WU Jin-long, LIU Bao-hua,et al. Tectonic and linear magnetic anamaly of Middle Okinawa Trough[J]. Acta Oceanologica Sinica, 2001, 23(2):69-78.] Google Scholar
[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. Google Scholar [LUAN Xi-wu,QIN Yun-shan.Gas seepage on the sea floor of Okinawa Trough Miyako Section[J].Chinese Science Bulletin,2005,50(13):1358-1365.] Google Scholar