An Investigation of Oil Spreading Coefficient in Carbonated Water+ Gas + Oil System: an Experimental Study in an Iranian Asphaltenic Oil Reservoir

To provide supplementary oil recovery after the primary and secondary processes, enhanced oil recovery (EOR) techniques are introduced. Carbonated water injection (CWI) as an EOR method can improve sweep efficiency and the risk of gas leakage. On the other hand, the interfacial tension (IFT) is one of the key factors which can affect fluid displacement during the process of CWI greatly. Therefore, the analysis of the IFT on an oil-carbonated water-CO2 system is vital. In this paper, the interfacial interactions of binary systems of asphaltenic crude oil (ACO), carbon dioxide (CO2), and carbonated water (CW) at different pressures and at two temperatures of 40 °C and 50 °C and their effects on the oil spreading in the water phase in the presence of gas are experimentally investigated. The IFT measurements were performed by axisymmetric drop shape analysis (ADSA) technique for the pendant/rising oil drop case. It is found out that the equilibrium interfacial tension (EIFT) of the two systems of crude oil-CO2 and water-CO2 is reduced almost linearly with pressure but increased with temperature. Moreover, the pressure has an increasing and decreasing effect on the water-oil and CW-oil IFT’s respectively. However, temperature has a reverse effect for the both systems. Spreading coefficient (SC) concept would help better understand the oil recovery mechanisms and potential. The results show that SC curve has a minimum point value as a specific pressure, which increases with temperature. The presence of CO2 in the water phase could strongly affect the oil spreading phenomenon through which oil recovery could be significantly enhanced.