Experimental and Mathematical Study of Water/Gas Two-Phase Flow at pore scale

Gas-water displacement is different from oil-water displacement because of higher interfacial tensions of gas-water respect to oil-water interfacial tensions. In this study, experimental measurements and theoretical modeling of gas-water displacement is employed to study the two phase flow mechanisms in pore scale. Then the influence of pore structure parameters including coordination number, aspect ratio and pore shape and size on the gas-water flow is investigated. 2D modeling of this process is presented in this study and simulation results are verified by comparing to experimental results where sufficient agreement was confirmed. The simulation results indicate that pore morphology and capillary number have significant influence on the competition between frontal displacement and snap-off. Frontal displacement leads to high recovery and snap off causes gas entrapment. It is concluded that increasing the pore and throat sizes, increasing the coordination number and increasing angularity (decreasing half angle) result in reducing residual gas amount. The results also indicate that residual gas saturation is not only a function of petrophysical property and pore morphology, but also it depends on flow rate and the experimental procedure.