Abstract 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 (kw) of methane hydrates in three fine quartz sands containing various hydrate saturation (SH) were carried out under steady water injection and production. Experimental results indicated that the effect of particle sizes on kw 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 kw 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 (krw) and SH 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 krw was eliminated, the Archie saturation exponent n tended to increase with the increase of SH, and n was recommended between 20 and 30.

中文翻译：

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水合物沉积物解离过程渗透率测量与发现

摘要 细石英砂中甲烷水合物渗透率的研究有助于准确预测气/水产量，并能有效表达流体运移特征。在本研究中，在稳定注水和生产条件下，研究了三种不同水合物饱和度（SH）的细石英砂中甲烷水合物的水有效渗透率（kw）。实验结果表明，尽管三种细石英砂的平均粒径差异相对有限，但粒径对 kw 的影响显着。渗透率测量过程中完整记录了水合物沉积物的压差，压差可以清楚地表示水合物的稳定和分解过程。随着水合物的分解和水合物沉积物中流道的出现，kw迅速增加。冷场发射扫描电子显微镜（CFE-SEM）原位记录了水合物的解离过程，孔隙空间中水合物的解离清晰可见，孔隙空间中的水合物首先被解离成许多小区域。在实验结果的基础上，提出了一种新的水相对渗透率（krw）与SH的折减模型，实验数据与占据孔隙中心的水合物拟合良好。消除了粒径对krw的影响，阿尔奇饱和指数n随着SH的增加而增加，推荐n在20～30之间。冷场发射扫描电子显微镜（CFE-SEM）原位记录了水合物的解离过程，孔隙空间中水合物的解离清晰可见，孔隙空间中的水合物首先被解离成许多小区域。在实验结果的基础上，提出了一种新的水相对渗透率（krw）与SH的折减模型，实验数据与占据孔隙中心的水合物拟合良好。消除了粒径对krw的影响，阿尔奇饱和指数n随着SH的增加而增加，推荐n在20～30之间。冷场发射扫描电子显微镜（CFE-SEM）原位记录了水合物的解离过程，孔隙空间中水合物的解离清晰可见，孔隙空间中的水合物首先被解离成许多小区域。在实验结果的基础上，提出了一种新的水相对渗透率（krw）与SH的折减模型，实验数据与占据孔隙中心的水合物拟合良好。消除了粒径对krw的影响，阿尔奇饱和指数n随着SH的增加而增加，推荐n在20～30之间。在实验结果的基础上，提出了一种新的水相对渗透率（krw）与SH的折减模型，实验数据与占据孔隙中心的水合物拟合良好。消除了粒径对krw的影响，阿尔奇饱和指数n随着SH的增加而增加，推荐n在20～30之间。在实验结果的基础上，提出了一种新的水相对渗透率（krw）与SH的折减模型，实验数据与占据孔隙中心的水合物拟合良好。消除了粒径对krw的影响，阿尔奇饱和指数n随着SH的增加而增加，推荐n在20～30之间。