Teng Ying, Liu Yu, Jiang Lanlan, Song Yongchen, Zhao Jiafei, Zhang Yi, Wang Dayong
Key laboratory of ocean energy utilization and energy conservation of ministry of education, Dalian university of technology, Dalian 116024, China.
Key laboratory of ocean energy utilization and energy conservation of ministry of education, Dalian university of technology, Dalian 116024, China.
Magn Reson Imaging. 2016 Sep;34(7):855-63. doi: 10.1016/j.mri.2016.03.004. Epub 2016 Mar 8.
Gravity drainage characteristics are important to improve our understanding of gas-liquid or liquid-liquid two-phase flow in porous media. Stable or unstable displacement fronts that controlled by the capillary force, viscous force, gravitational force, etc., are relevant features of immiscible two-phase flow. In this paper, three dimensionless parameters, namely, the gravity number, the capillary number and the Bond number, were used to describe the effect of the above mentioned forces on two-phase drainage features, including the displacement front and final displacing-phase saturation. A series of experiments on the downward displacement of a viscous fluid by a less viscous fluid in a vertical vessel that is filled with quartz beads are performed by using magnetic resonance imaging (MRI). The experimental results indicate that the wetting properties at both high and low capillary numbers exert remarkable control on the fluid displacement. When the contact angle is lower than 90°, i.e., the displaced phase is the wetting phase, the average velocity Vf of the interface of the two phases (displacement front velocity) is observably lower than when the displaced phase is the non-wetting phase (contact angle higher than 90°). The results show that a fingering phenomenon occurs when the gravity number G is less than the critical gravity number G'=Δμ/μg. Moreover, the higher Bond number results in higher final displacing-phase saturation, whereas the capillary number has an opposite effect.
重力排水特性对于增进我们对多孔介质中气液或液液两相流的理解非常重要。由毛细力、粘性力、重力等控制的稳定或不稳定驱替前沿是不混溶两相流的相关特征。本文使用三个无量纲参数，即重力数、毛细数和邦德数，来描述上述力对两相排水特性的影响，包括驱替前沿和最终驱替相饱和度。通过磁共振成像（MRI）对在充满石英珠的垂直容器中低粘性流体向下驱替高粘性流体进行了一系列实验。实验结果表明，在高毛细数和低毛细数下的润湿性对流体驱替都有显著控制作用。当接触角小于90°，即被驱替相为润湿相时，两相界面的平均速度Vf（驱替前沿速度）明显低于被驱替相为非润湿相时（接触角大于90°）。结果表明，当重力数G小于临界重力数G'=Δμ/μg时会出现指进现象。此外，邦德数越高，最终驱替相饱和度越高，而毛细数则有相反的影响。
