Page 195 - Gas Wettability of Reservoir Rock Surfaces with Porous Media
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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.
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