Japan Geoscience Union Meeting 2015

Presentation information


Symbol M (Multidisciplinary and Interdisciplinary) » M-IS Intersection

[M-IS24] Gas hydrates in environmental-resource sciences

Thu. May 28, 2015 2:15 PM - 4:00 PM 102B (1F)

Convener:*Hitoshi Tomaru(Department of Earth Sciences, Chiba University), Akihiro Hachikubo(Environmental and Energy Resources Research Center, Kitami Institute of Technology), Sumito Morita(Institute for Geo-Resources and Environment, National Institute of Advanced Industrial Science and Technology), Chair:Kida Masato(National Institute of Advanced Industrial Science and Technology)

2:45 PM - 3:00 PM

[MIS24-22] Characterization of grain-size distribution and mineral composition of hydrate-bearing sediments in the Nankai Trough

*Hideki MINAGAWA1, Takuma ITO1, Kosuke EGAWA1, Hiroaki KANEKO1, Shohei NODA1, Tetsuya FUJII2, Jiro NAGAO1 (1.MHRC/ AIST, 2.JOGMEC)

Gas hydrate-bearing sediments taken by a hybrid pressure coring system (Hybrid PCS corer) were recovered from the eastern Nankai Trough region at the AT-1 well during the 2012 JOGEMC/JAPEX Pressure coring operation using D/V Chikyu. The recovered sediments are mainly composed of the unconsolidated sand and mud alternation layers, which can be interpreted as turbidite and hemi-pelagic mud, respectively. Gas hydrates accumulated in unconsolidated sands as a pore-filling morphology. The purpose of our study is to prepare the standard samples, which represent the sedimentary features such as grain size and mineral composition in the eastern Nankai Trough sediments. For preparing the standard sample appears to be important for laboratory experimental studies such as physical properties from the engineering point of view.
Using the gas hydrate-bearing sediments, the sedimentary features such as gain size and mineral composition were analyzed systematically. Based on this grain size distribution data, we categorized typical three kinds of standards samples: silty sand, sandy silt, and clayey silt, respectively. As a result of mineral composition analysis of sediment measured by X-ray diffraction (XRD), the bulk mineral compositions are characterized by 10 compositions, i.e., the quartz, hornblende, feldspars (orthoclase, Plagioclase), pyrite, smectite, kaolinite, calcium carbonate, chlorite, and mica. These mineral compositions are strongly correlated with grain size features such as median or means sizes. According to the above results, we prepared typical three kinds of standard samples, and measured pore-size distribution and permeability features using the nuclear magnetic resonance (NMR) method. In the presentation, we will compare with those physical features between standard samples and natural sediments from the eastern Nankai Trough.
This work was financially supported by the Research Consortium for Methane Hydrate Resources in Japan (MH21 Research Consortium) of the National Methane Hydrate Exploitation Program planned by the Ministry of Economy Trade and Industry (METI).