Journal of Marine Science and Engineering (Apr 2024)

Pore Water Conversion Characteristics during Methane Hydrate Formation: Insights from Low-Field Nuclear Magnetic Resonance (NMR) Measurements

  • Jiaxian Wang,
  • Yunkai Ji,
  • Changling Liu,
  • Qingguo Meng,
  • Yapeng Zhao,
  • Zhun Zhang,
  • Jianye Sun,
  • Lele Liu,
  • Fulong Ning

DOI
https://doi.org/10.3390/jmse12040619
Journal volume & issue
Vol. 12, no. 4
p. 619

Abstract

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Understanding the conversion characteristics of pore water is crucial for investigating the mechanism of hydrate accumulation; however, research in this area remains limited. This study conducted methane hydrate formation experiments in unconsolidated sands using an in-house low-field nuclear magnetic resonance (NMR) system. It focused on pore water conversion characteristics and influencing factors such as initial water saturation and sand particle sizes. Results show that methane hydrate formation enhances the homogeneity of the effective pore structure within sand samples. The conversion rate of pore water is significantly influenced by differences in heat and mass transfer capacity, decreasing as initial water saturation and sand size increase. Pore water cannot be fully converted into hydrates in unconsolidated sands. The final conversion ratio of pore water in water-poor sand samples nears 97%, while in water-rich sand samples, it is only 65.80%. Sand particle size variation has a negligible impact on the final conversion ratio of pore water, with ratios exceeding 94% across different particle sizes, differing by less than 3%.

Keywords