Marine controlled source electromagnetic method used for the gas hydrate investigation in the offshore area of SW Taiwan

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Title:	Marine controlled source electromagnetic method used for the gas hydrate investigation in the offshore area of SW Taiwan
Authors:	蔡沁煇;Hsu, Shu-Kun;Chiang, Chih-Wen;Evans, Rob L.;Chen, Chow-Son;Chiu, Shye-Donq;Ma, Yu-Fang;Chen, Song-Chuen;Tsai, Ching-Hui;Lin, Shiao-Shan;Wang, Yunshuen
Contributors:	環境研究中心
Keywords:	EM method;Gas hydrate;Gas seepage;Pockmark;SW Taiwan
Date:	2014-10-01
Issue Date:	2026-04-23 15:02:20 (UTC+8)
Publisher:	Elsevier Ltd.;Elsevier Ltd
Abstract:	摘要： •The results of first marine resistivity survey off SW Taiwan are presented.•Pockmark areas near off SW Taiwan show high resistivity anomalies.•Gas hydrate is inferred in the shallow seabed near the Good-Weather-Ridge. Bottom simulating reflectors (BSRs), high methane flux, shallow sulfide/methane interfaces, fluids venting from the seafloor, authigenic carbonates within sediments, methane reefs, and self-biomes are common seafloor features in the area off southwest Taiwan. The geophysical and geochemical signatures of these features suggest a high potential for gas hydrate (GH) reservoirs in the region. The BSRs are typically interpreted as the boundary between free gases and solid hydrate, whereas the upper reaches of the hydrate stability zone and the distribution of gas hydrate in shallow sediments are not well understood. This study shows the first results of a marine controlled-source electromagnetic survey, conducted in the offshore area of SW Taiwan in 2010. The survey aimed to provide electrical resistivity information of the shallow sediments. Three target areas were surveyed: (1) an area to the southeast of the Xiaoliuchiu Island (gas seep G96), (2) an area in the west of the Yung-An Ridge (YAR) and (3) an area in the northwest of the Good Weather Ridge (GWR). In total, fourteen survey lines with a total length of 72km were completed. Our preliminary results show that relatively high resistivity anomalies occur within pockmarks and at gas seepage sites. The apparent resistivity is estimated to be about 1Ohm-m higher than background in G96 and YAR sites, while an anomaly up to 2Ohm-m is found in the GWR. At gas seep site G96, the high resistivity anomaly may be due to the existence of authigenic carbonates; whereas, the high resistivity anomaly in the NW of the GWR site may also be due to the existence of gas hydrate in the shallow seabed. Based on the resistivity anomaly, the gas hydrate saturation is about 16% in the shallow sediments below the pockmark area in the northwest side of the GWR site. 出版者： Elsevier Ltd 出版日期： 2014-10-01 出處： Journal of Asian Earth Sciences, 2014-10, Vol.92, p.224-232 資源來源： Elsevier ScienceDirect Journals Complete 版權： 2013 Elsevier Ltd 識別號： ISSN: 1367-9120 識別號： EISSN: 1878-5786 識別號： DOI: 10.1016/j.jseaes.2013.12.001
Appears in Collections:	[Center for Environmental Studies] journal & Dissertation

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