Modelling Formation of a New Fluid Phase During Carbonated Water Injection

Abstract

Abstract Direct flow visualisation experiments have revealed that the transfer of CO2 from water into crude oil triggers the formation of a new gas-like phase within the oil. The new phase will subsequently expand and contributes significantly to oil recovery. In this study, we first develop a methodology to describe the formation of the new phase based on our visual observation obtained from our high-pressure micromodel experiments. We then use a commercial simulator (Fluid Modelling Package) and tune an equation-of-state using PVT data of the oil reservoir of interest. The proposed methodology is then employed to examine the capability of commercial simulators to model the experimentally observed process of new phase formation. The outcome of this simulation exercise verifies that the dissolution of CO2 into the oil phase would expel the lighter components of the oil forming a gaseous phase with much higher swelling factor compared to the normal swelling of a crude oil due to CO2 dissolution. The higher swelling of the new phase outperforms other oil recovery mechanisms considered for carbonated water injection and is the dominant factor controlling the amount of oil recovery and the performance of the oil recovery process. The new phase becomes heavier as the CO2 transfer from water to crude oil continues and reduces the IFT (interfacial tension) between the oil and the newly formed gaseous phase. The results of the study help improving the accuracy of the numerical simulation of the oil recovery processes involving CO2 and carbonated water injection. This will in turn improve the quality of our reservoir performance predictions and the reliability of our economic calculations of these enhanced oil recovery techniques.