Identification of gas hydrate dissociation from wireline-log data in the Shenhu area, South China Sea

CORC > 海洋研究所 > 中国科学院海洋研究所 > 海洋地质与环境重点实验室

	Identification of gas hydrate dissociation from wireline-log data in the Shenhu area, South China Sea
	Wang, Xiujuan 1; Lee, Myung 2; Wu, Shiguo 1; Yang, Shengxiong 3
刊名	GEOPHYSICS
	2012-05-01
卷号	77 期号:3 页码:B125-B134
关键词	UNCONSOLIDATED SEDIMENTS SEISMIC ATTENUATION WAVE VELOCITY SATURATION MARGIN STABILITY INVERSION SLOPE BRINE CORE
ISSN号	0016-8033
通讯作者	Wang, XJ (reprint author), Chinese Acad Sci, Inst Oceanol, Key Lab Marine Geol & Environm, Qingdao, Peoples R China.
英文摘要	Wireline logs were acquired in eight wells during China's first Etas hydrate drilling expedition (GMGS-1) in April June of 2007. Well logs obtained from site SH3 indicated gas hydrate was present in the depth range of 195-206 in below seafloor with a maximum pore-space gas hydrate saturation, calculated from pore water freshening, of about 26%. Assuming gas hydrate is uniformly distributed in the sediments, resistivity calculations using Archie's equation yielded hydrate-saturation trends similar to those from chloride concentrations. However, the measured compressional (P-wave) velocities decreased sharply at the depth between 194 and 199 mbsf, dropping as low as 1.3 km/s, indicating the presence of free gas in the pore space, possibly caused by the dissociation of gas hydrate during drilling. Because surface seismic data acquired prior to drilling were not influenced by the in situ gas hydrate dissociation, surface seismic data could be used to identify the cause of the low P-wave velocity observed in the well log. To determine whether the low well-log P-wave velocity was caused by in situ free gas or by gas hydrate dissociation, synthetic seismograms were generated using the measured well-log P-wave velocity along with velocities calculated assuming both gas hydrate and free gas in the pore space. Comparing the surface seismic data with various synthetic seismograms suggested that low P-wave velocities were likely caused by the dissociation of in situ gas hydrate during drilling.
学科主题	Geochemistry & Geophysics
收录类别	SCI
原文出处	10.1190/GEO2011-0324.1
语种	英语
WOS记录号	WOS:000304584400005
公开日期	2013-09-24
内容类型	期刊论文
源URL	[http://ir.qdio.ac.cn/handle/337002/12507]
专题	海洋研究所_海洋地质与环境重点实验室
作者单位	1.Chinese Acad Sci, Inst Oceanol, Key Lab Marine Geol & Environm, Qingdao, Peoples R China 2.US Geol Survey, Denver, CO 80225 USA 3.MLR, Guangzhou Marine Geol Survey, Guangzhou, Guangdong, Peoples R China
推荐引用方式 GB/T 7714	Wang, Xiujuan,Lee, Myung,Wu, Shiguo,et al. Identification of gas hydrate dissociation from wireline-log data in the Shenhu area, South China Sea[J]. GEOPHYSICS,2012,77(3):B125-B134.
APA	Wang, Xiujuan,Lee, Myung,Wu, Shiguo,&Yang, Shengxiong.(2012).Identification of gas hydrate dissociation from wireline-log data in the Shenhu area, South China Sea.GEOPHYSICS,77(3),B125-B134.
MLA	Wang, Xiujuan,et al."Identification of gas hydrate dissociation from wireline-log data in the Shenhu area, South China Sea".GEOPHYSICS 77.3(2012):B125-B134.