Abstract:

Macro drainage characters were determined by micro drainage features in pore scale. They are inhomogeneous everywhere in different directions. Three distinctive Hele-Shaw cells were designed to study the effects of pore structure on drainage process. The pore structure characters were elucidated by several parameters including pore angle, critical ratio (the ratio of the max pore diameter to the min throat size), tortuosity and porosity. The results show that when displacement velocity is the same, larger pore angle or smaller tortuosity results in greater non-wetting phase (dodecane and hexadecane) saturation; when displacement velocity is not the same, larger displacement velocity makes greater non-wetting phase saturation. Critical ratio and porosity are not the decisive factors; their effects on drainage process are evaluated by their values and other pore structure parameters, such as pore angle and so on. When pore angle and displacement velocity are the same, smaller viscosity ratio pairs tend to have a higher drainage effect.

Key words: drainage character, pore angle, critical ratio, tortuosity

摘要：

两相宏观排驱特性是由微观孔隙尺度排驱特性决定的，而微观孔隙尺度多孔介质又处处不均匀、各向不均匀。为了研究孔隙尺度孔隙结构特征对驱替特性的影响，采用了独特设计的微多孔实验段，固定骨架圆柱间距离而变动驱替流体可流通方向，在此基础上研究了孔隙结构特征对驱替特性的影响。对于孔隙特性的表征采取了孔隙方向、关键比率（最大孔隙尺度与最小孔喉尺度比值）、迂曲度和孔隙率四个参数。结果表明：同流量时，微多孔结构的孔隙角越大、迂曲度越小，则对应的非浸润相（十二烷和十六烷）的饱和度（驱替效率）越高；对于不同流量，所有的微多孔结构都按照流量越大，则非浸润相（十二烷和十六烷）饱和度越高的规律变化；关键比率和孔隙率影响必须结合孔隙结构来判断；孔隙角、流量相同时，两相黏度接近的驱替效率更高。

关键词: 排驱特性, 孔隙角, 关键比率, 迂曲度