Nature gas hydrates (NGHs) are considered as an ideal substitute for traditional fossil fuel. The evaluation of the physical properties of hydrate-bearing sediment (HBS) is important to develop reasonable exploitation strategies and clarify the corresponding main controlling factors. In this study, to determine the influence of grain size distribution on the physical properties of HBSs, 24 hydrate-bearing models were reconstructed based on a novel pore-scale 3D morphological modeling algorithm. A series of pore system evaluations and permeability simulations were carried out by pore network modeling (PNM). Moreover, thermal and electrical simulations were carried out using the finite volume method (FVM). The results are as follows: (1) The smaller the grain size is, the smaller the radius of the pores and throats of HBSs will be, which makes it easier for the connectivity between pores and throats to deteriorate as the hydrate saturation increases. (2) With increasing hydrate saturation, the permeability of HBSs gradually decreases. According to the decline rate, it can be divided into two stages: in the first stage, it will decrease sharply, while in the second stage, it will decrease slowly. In general, the smaller the grain size is, the lower the permeability of HBSs will be. (3) The apparent thermal conductivity of HBSs will increase as the hydrate saturation increases. The smaller the grain size is, the higher the apparent thermal conductivity will be. (4) The smaller the grain size is, the lower the apparent electrical conductivity and the higher the resistivity index under the same hydrate saturation will be.

中文翻译：

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粒度分布对胶结水合物沉积物物理特征的影响

天然气水合物（NGH）被认为是传统化石燃料的理想替代品。含水合物沉积物（HBS）物性评价对于制定合理的开发策略、明确相应的主控因素具有重要意义。在本研究中，为了确定粒度分布对 HBS 物理性质的影响，基于新型孔隙尺度 3D 形态建模算法重建了 24 个含水合物模型。通过孔隙网络建模（PNM）进行了一系列孔隙系统评估和渗透率模拟。此外，使用有限体积法（FVM）进行热模拟和电模拟。结果表明:(1)晶粒尺寸越小,HBS孔喉半径越小,随着水合物饱和度的增加,孔喉连通性更容易恶化。(2)随着水合物饱和度的增加，HBSs的渗透率逐渐降低。根据下降幅度，可分为两个阶段：第一阶段急剧下降，第二阶段缓慢下降。一般来说，晶粒尺寸越小，HBS 的渗透性越低。(3) HBSs的表观导热系数随着水合物饱和度的增加而增加。晶粒尺寸越小，表观导热系数越高。(4) 晶粒尺寸越小，表观电导率越低，相同水合物饱和度下的电阻率指数越高。