Decomposition of methane hydrates in sand, sandstone, clays and glass beads

Tsutomu Uchida, Satoshi Takeya, Evgene M. Chuvilin, Ryo Ohmura, Jiro Nagao, Vladimir S. Yakushev, Vladimir A. Istomin, Hideki Minagawa, Takao Ebinuma, Hideo Narita

研究成果: Article査読

131 被引用数 (Scopus)

抄録

Decomposition conditions of methane hydrates in sediments were measured during formation-decomposition cycles. As test sediments, we used silica sand, sandstone, and clays (kaoline and bentonite), which are typical natural materials known as hydrate bearing sediments, and the range of samples cover a range of water saturating abilities. To better understand the results, we also used uniformly sized glass beads. Pore effects on decomposition of these materials were investigated by analyzing the pore-space distributions of the materials and by varying the initial water content of the samples. The results obtained for sand and sandstone samples indicated that the final decomposition temperatures were shifted lower than those for bulk hydrates at the same pressure. Temperature shifts were more negative for smaller initial water contents with the maximum shift being approximately -0.5 K. The results were consistent with those measured for glass beads with nearly the same particle size. For kaoline clays, the shift was at most - 1.5 K. We conclude that the decomposition conditions are mainly affected by the pore sizes. The surface textures and mineral components had less influence on the results. We confirmed that glass beads mimic the effect of sediments for sand, sandstone, and kaoline clays, which have little to no swelling when put in contact with water. On the other hand, for bentonite particles, the results indicated that methane hydrates formed not only between the particles but also in the interlayers. A thermodynamic promoting effect was found for dilute bentonite solutions, although the positive decomposition-temperature shift was at most +0.5 K.

本文言語English
ページ(範囲)B05206 1-12
ジャーナルJournal of Geophysical Research: Solid Earth
109
5
DOI
出版ステータスPublished - 2004 5月 10
外部発表はい

ASJC Scopus subject areas

  • 地球物理学
  • 地球化学および岩石学
  • 地球惑星科学(その他)
  • 宇宙惑星科学

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