Permeability measurement and discovery of dissociation process of hydrate sediments

The study on the permeability of methane hydrates in fine quartz sands contributes to the accurate prediction of gas/water production and can effectively express the characteristics of fluid migration. In this study, the water effective permeability (k(w)) of methane hydrates in three fine quartz sa...

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Bibliographic Details
Published in:Journal of Natural Gas Science and Engineering
Main Authors: Shen, Pengfei, Li, Gang, Li, Bo, Li, Xiaosen, Liang, Yunpei, Lv, Qiunan
Format: Report
Language:English
Published: ELSEVIER SCI LTD 2020
Subjects:
Methane hydrates
Permeability
Dissociation
Saturation
Reduction model
METHANE-HYDRATE
RELATIVE PERMEABILITY
POROUS-MEDIA
GAS-PRODUCTION
NATURAL-GAS
WATER
CH4
DEPRESSURIZATION
PERMAFROST
Energy & Fuels
Engineering
Chemical
Methane hydrate
permafrost
Online Access:http://ir.giec.ac.cn/handle/344007/26395
https://doi.org/10.1016/j.jngse.2020.103155
Description
Summary:The study on the permeability of methane hydrates in fine quartz sands contributes to the accurate prediction of gas/water production and can effectively express the characteristics of fluid migration. In this study, the water effective permeability (k(w)) of methane hydrates in three fine quartz sands containing various hydrate saturation (S-H) were carried out under steady water injection and production. Experimental results indicated that the effect of particle sizes on k(w) was significant even though the difference in the average particle size of three fine quartz sands was relatively limited. The differential pressure of the hydrate sediments was completely recorded during permeability measurement, and the stabilization and decomposition process of hydrate could be clearly represented by differential pressure. The k(w) increased rapidly with the decomposition of hydrate and the appearance of flow channel in the hydrate sediments. Hydrate dissociation process was recorded in situ by Cold Field Emission Scanning Electron Microscopy (CFE-SEM), the dissociation of hydrates in pore space was clearly visible, and the hydrates in pore space were first dissociated into many small regions. A new reduction model between water relative permeability (k(rw)) and S-H was proposed on the basis of experimental results, and the experimental data fitted well with hydrates occupying pore centers. The effect of particle sizes on k(rw) was eliminated, the Archie saturation exponent n tended to increase with the increase of S-H, and n was recommended between 20 and 30.

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