Abstract:Carbonized intelligent water flooding is a new chemical combined oil recovery method. How to improve the solubility of CO2 in salt water is the key to effectively reduce the interfacial tension between oil and water. The formation water with high salinity was diluted as smart water, and CO2 was added to the smart water with different concentrations of mutual solvent under different pressures. The interfacial tension measurement experiment was carried out to study the influence of mutual solvent on the interfacial tension between smart water and carbonized smart water and crude oil, and the influence of salinity, mutual solvent concentration and pressure on the interfacial tension of oil and water was clarified. The experimental results show that the density of the mixed liquid and carbonized smart water decreases with the increase of the organic mutual solvent concentration, and with the increase of the system pressure, the density of the mixed liquid slightly increases, while the density of the carbonized smart water decreases. Under constant pressure, the interfacial tension between the mixed liquid and crude oil decreases with the increase of the mutual solvent concentration in the mixed liquid, and decreases with the decrease of the salinity, but it is less affected by the system pressure, and the decrease of the interfacial tension of the mixed liquid under DME is greater than that of methanol. When CO2 is added to smart water, the interfacial tension of oil and water can be further reduced. The interfacial tension between carbonized smart water and crude oil decreases with the increase of mutual solvent concentration, and decreases with the decrease of salinity and system pressure. Among them, the interfacial tension between the carbonized smart water and crude oil is the smallest when 10% formation water is added with 15% DME and then 9MPa CO2 is added, and the interfacial tension is reduced by 88.2%. The research results provide a new method for the continuous development of old oil fields with high water cut and the improvement of water flooding recovery.