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Effect of Gas Wettability on Capillaries CHAPTER 5 179
5.2.1.2 EXPERIMENT PRINCIPLES AND METHODS
In porous media, gas/liquid phases percolation are mainly affected by pore
structure, displacing pressure, viscous force, capillary force, and gravity [3].
During the experiment, the porous media is placed horizontally with an ideal
network model having a certain pore structure to ensure that the gas liquid
percolation isn’t affected by gravity and pore structures. When the displacing
pressure is lower, the two-phase movement is mainly affected by capillary
force; when displacing speed is higher, the two-phase movement is mainly
affected by displacing pressure and viscous force [4].
Based on the formula for capillary force:
2σcosθ
P c 5 (5.3)
r
In the formula; r is the radius of channels; σ is the surface tension; θ is the contact angle:
To investigate the effect of gas wettability on the two-phase percolation of
micro models, a peristaltic pump was used for microinjection displacement
(0.3 mL/h). When the fluid is in the wetting phase, the capillary force is the
power of the flowing fluid, and when the fluid is in the nonwetting phase, the
capillary force is the flow resistance of fluid. Only when the displacement pres-
sure reaches the capillary force does the fluid begin to flow. Therefore, the
experiment studies the effects of wettability on the micro percolation process
of gas liquid phases.
5.2.1.2.1 Preparing the Micromodel
The etched glass network model is made with ultraviolet lithography technol-
ogy [5]. The pore structure and size of is the model is as shown in Fig. 5.13.
Model dimension: nine horizontal capillary tubes and eight vertical capillary
FIGURE 5.13
Diagram of etched glass network model of ideal pore structures.