&nbsp; &nbsp; &nbsp; &nbsp; The pore-scale displacement phenomenon for gas-liquid flow is common in nature. Gas-liquid displacement is still a complex and challenging topic in the field of nonequilibrium physics and many industrial applications, while it is essential to obtain a clear picture regarding the mechanisms of invasion and percolation.&nbsp; &nbsp; &nbsp; &nbsp; In this study, pore-scale displacement of gas-liquid flow in a porous medium was investigated. A digital image analysis method (DIA) was used to process the images. The invasion patterns were captured by a high-speed camera and Invasion morphologies were analysed. The invasion pattern demonstrated that an increase in viscosity of the displaced liquid tends to decrease the finger width and the number of fingers. The effect of liquid viscosity on the gas tip velocity was also investigated. At 50 mL/h, it is found that the velocity decreases with the increase of viscosity of the displaced liquid, because a higher viscosity prevents gas invasion. However, the velocity increases with the increase of liquid viscosity at 10 mL/h. It is reasonable based on the mass balance of the gas phase, considering the decrease in finger width as liquid viscosity increases at the gas flow rate of 10 mL/h. Among the six cases, the highest tip velocity is 0.1415 m/s when N2 invades into de-ionized water at the gas flow rate of 50 mL/h. The breakthrough time is also an important parameter to characterize invasion morphology. At a gas flow rate of 50 mL/h, the breakthrough time increases as the viscosity of the displaced liquid increases, while the breakthrough time decreases as the liquid viscosity increases at a gas flow rate of 10 mL/h. &nbsp;Then the displacement ratio was measured to estimate the N2 injection efficiency. The N2 displacement ratio decreases with the increase of liquid viscosity and gas flow rate. A higher gas flow rate favors moving forward because of a higher gas inertia, and the finger becomes thinner as well, so the area of its displacement decreases accordingly. In addition, the invasion dynamics was studied. It reveals that the gas tip moves in a stepwise way, i.e., the tip goes forward, and then it stays there for a while and then goes forward again. The gas tip splits and expands in side directions and also moves backward when the gas pressure is not high enough to overcome the forward capillary pressure, which can be found for all the displaced liquids in this study.

Experimental Study of Gas-Liquid Displacement in a Porous Media Microchip by Digital Image Analysis Method

Paper Proceedings: https://asmedigitalcollection.asme.org/IMECE/IMECE2021/volume/85543

ASME 2021 International Mechanical Engineering Congress and Exposition (IMECE2021)

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