Abstract: The change of hydrate saturation in the process of natural gas hydrate exploitation will cause the corresponding change of reservoir permeability. And it will affect the process of natural gas hydrate exploitation. To study the effect of natural gas hydrate on porous media seepage characteristics, the pore network model is applied to study the change of seepage characteristics of porous media. Hydrate forms in two ways, which are wall surface and pore center, compared with relevant models. It is found that the absolute permeability of hydrate formation the pore center is less than that generated on wall surface. When the hydrate saturation is the same, the radius of porous media is larger, then the permeability is bigger. The isotonic point of two phase relative permeability of hydrate formation in pore center is less than that generated on wall surface. When hydrate saturation changes, two phase relative permeability is almost constant. It also gives the corresponding relationship between reservoir permeability and hydrate saturation.

Key words: natural gas hydrate, pore network model, absolute permeability, relative permeability

摘要： 天然气水合物开采过程中水合物饱和度的变化会引起储层渗透率的相应变化, 对开采过程造成影响。为研究天然气水合物对多孔介质渗流特性的影响, 本文基于孔隙网络模型模拟研究了水合物生成于壁面与中心两种方式下, 多孔介质渗流特性变化, 并与相关模型进行比较。结果表明, 水合物生成于中心时绝对渗透率小于生成于壁面时;水合物饱和度相同时多孔介质孔径越大, 渗透率越大;水合物生成于中心时两相相对渗透率等渗点小于生成于壁面时;当水合物饱和度变化时两相相对渗透率几乎不变。说明了储层渗透率与水合物饱和度之间有相对应的关系。

关键词: 天然气水合物, 孔隙网络模型, 绝对渗透率, 相对渗透率