LAUSR

Abstract Interfacial Tension (IFT) is one of the most important parameters controlling the production during enhanced oil recovery phase. However, carbonated water injection (CWI), despite its reported applications, has not been totally successful to reduce the IFT between oil and brine. On the other hand, low salinity water (LSW) has been indicated as an effective method of reducing the IFT. Thus, if the CWI can be combined with LSW, with the mechanisms understood, a great step can be taken towards a better production from depleted reservoirs. In this study, the application of low salinity carbonated water (LSCW) injection was studied and attempts were made to understand the mechanisms involved in the presence of salt ions (NaCl and CaCl2) and carbon dioxide. The results obtained indicated that increasing the solubility of CO2 within the aqueous phase reduces the equilibrium interfacial tension (EIFT). It was also found that the EIFT of LSCW decreases by 51.8% compared to high salinity water during the laboratory measurements. It appears that the aging time was can improve the surface performance of the carbonated water (CW) once LSW is used. Furthermore, IFT reduction over time in LSCW was higher than the high salinity carbonated water (HSCW). It was argued that “salting in” effect is the major mechanism behind the reduction of IFT during the LSCW injection. Therefore, LSCW flooding can be considered as a competent enhanced oil recovery (EOR) method which can reduce the IFT and increase the microscopic efficiency for a better production.