Granular experiments of thrust wedges: Insights relevant to methane hydrate exploration at the Nankai accretionary prism

Yasuhiro Yamada, Kei Baba, Ayumu Miyakawa, Toshifumi Matsuoka

研究成果: ジャーナルへの寄稿学術誌査読

30 被引用数 (Scopus)


The accumulation mechanism of methane hydrates has been a central issue in previous hydrate research regarding the Nankai accretionary prism, southwest of Japan. Expulsion of formation fluids is significant during the prism accretion process, and the migration of these methane-bearing fluids exerts a strong control on the accumulation of hydrates. Two types of fluid pathways, inter-granular porosity and faults, need to be evaluated to understand hydrate accumulation. Fluid migration along faults can be partly modeled by examining faulting activity. Our study modeled the accretion process by using two granular methods that approximated the geologic body as an assemblage of particles: (1) analog experiments using granular materials, and (2) a numerical simulation based on the distinct element method. The analog experiments closely reproduced the prism geometry observed in seismic profiles across the Nankai accretionary prism. Digital image correlation analysis indicated that the frontal thrust is generally active but older structures are also frequently reactivated. The numerical simulations produced prism geometries similar to those of the analog experiments. The velocity distributions of the particles showed evidence of episodic faulting and reactivation, but the internal stress field exhibited little change in the deeper part of the prism during deformation. The frequent and substantial changes in fault activity displayed by the models indicate episodic fluid flow along fault surfaces. Active frontal thrusting suggests that formation fluids generally migrate from deep within the prism to the deformation front, but may move along reactivated older faults. Inter-granular permeability also fluctuates, as it is controlled by temporal and spatial variations in the internal stress field. However, fluid flow is likely to be relatively stable in the deeper segment of the prism.

ジャーナルMarine and Petroleum Geology
出版ステータス出版済み - 3月 2014

!!!All Science Journal Classification (ASJC) codes

  • 海洋学
  • 地球物理学
  • 地質学
  • 経済地質学
  • 層序学


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