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Elevated gas hydrate saturation within silt and silty clay sediments in the Shenhu area, South China Sea

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dc.contributor.author Wang, Xiujuan
dc.contributor.author Hutchinson, Deborah R.
dc.contributor.author Wu, Shiguo
dc.contributor.author Yang, Shengxiong
dc.contributor.author Guo, Yiqun
dc.date.accessioned 2011-06-13T15:49:20Z
dc.date.available 2011-11-25T09:28:59Z
dc.date.issued 2011-05-25
dc.identifier.citation Journal of Geophysical Research 116 (2011): B05102 en_US
dc.identifier.uri http://hdl.handle.net/1912/4642
dc.description Author Posting. © American Geophysical Union, 2011. This article is posted here by permission of American Geophysical Union for personal use, not for redistribution. The definitive version was published in Journal of Geophysical Research 116 (2011): B05102, doi:10.1029/2010JB007944. en_US
dc.description.abstract Gas hydrate saturations were estimated using five different methods in silt and silty clay foraminiferous sediments from drill hole SH2 in the South China Sea. Gas hydrate saturations derived from observed pore water chloride values in core samples range from 10 to 45% of the pore space at 190–221 m below seafloor (mbsf). Gas hydrate saturations estimated from resistivity (Rt) using wireline logging results are similar and range from 10 to 40.5% in the pore space. Gas hydrate saturations were also estimated by P wave velocity obtained during wireline logging by using a simplified three-phase equation (STPE) and effective medium theory (EMT) models. Gas hydrate saturations obtained from the STPE velocity model (41.0% maximum) are slightly higher than those calculated with the EMT velocity model (38.5% maximum). Methane analysis from a 69 cm long depressurized core from the hydrate-bearing sediment zone indicates that gas hydrate saturation is about 27.08% of the pore space at 197.5 mbsf. Results from the five methods show similar values and nearly identical trends in gas hydrate saturations above the base of the gas hydrate stability zone at depths of 190 to 221 mbsf. Gas hydrate occurs within units of clayey slit and silt containing abundant calcareous nannofossils and foraminifer, which increase the porosities of the fine-grained sediments and provide space for enhanced gas hydrate formation. In addition, gas chimneys, faults, and fractures identified from three-dimensional (3-D) and high-resolution two-dimensional (2-D) seismic data provide pathways for fluids migrating into the gas hydrate stability zone which transport methane for the formation of gas hydrate. Sedimentation and local canyon migration may contribute to higher gas hydrate saturations near the base of the stability zone. en_US
dc.description.sponsorship Our research is supported by the National Basic Research Program (2009CB219505), International Science & Technology Cooperation program of China (2010DFA21740), and National Natural Science Foundation of China (40930845). en_US
dc.format.mimetype application/pdf
dc.language.iso en_US en_US
dc.publisher American Geophysical Union en_US
dc.relation.uri http://dx.doi.org/10.1029/2010JB007944
dc.subject Gas hydrate en_US
dc.subject Saturation en_US
dc.subject Shenhu area en_US
dc.subject Fine-grained en_US
dc.subject Gas chimney en_US
dc.title Elevated gas hydrate saturation within silt and silty clay sediments in the Shenhu area, South China Sea en_US
dc.type Article en_US
dc.identifier.doi 10.1029/2010JB007944


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