In relation with the potential applications of CO2 foam technology on Enhanced Oil recovery and carbon geological storage, the paper experimentally and numerically investigated the foam assisted CO2 displacement process in a water/oil pre-saturated porous media. Computational Tomography (CT) technology is employed to visualize the transient sweep process of CO2 foam flow in porous media and the three phase saturation distributions along the sample core are obtained through double-energy CT scan scheme. Studying parameters for laboratory research include type of internal phase of foam fluid, the system pressure and the permeability of the porous media. It is found the foam fluid could push most of the liquid phase content in the latter part of the porous media but leaves the forepart of the sample less flooded, showing a clear entrance effect for foam propagation process in porous media. Compared to the CO2 foam, the inlet behavior for N2 foam is even more profound. The pressure loss for CO2 foam flow is much higher in lower permeable porous media of 179md, which in turn leads to higher oil recovery rate of 10.3% versus 6% in high permeable core samples of 3500md. Due to the increased CO2 solubility, elevated system backpressure leads to less pressure drop for CO2 foam flooding processes without compromising the oil displace capability of CO2 foam fluid. Through introducing the novel stochastic bubble population balance model, which employs only two parameters of bubble generation rate of Kg and the maximum bubble number of n∞, numerical investigations are also carried out concerning foam displacement behavior in porous media. The distribution characteristics of pressure, water saturation and bubble density are analyzed to reveal in mechanism the experimental observed inlet behavior for foam flow in the porous media. Parametrical numerical studies indicate higher Kg values could significantly suppress the entrance effect for foam flow in porous media, whereas the increased n∞ values have little effect on the water saturation distribution in the entrance region of the porous media.
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