Comparative study of oil spreading characteristics for water and carbonated water systems using live and dead oils

Abstract

In order to investigate the potential of water alternating gas (WAG) and carbonated water alternating gas (CWAG) injection methods, a series of interfacial tension (IFT) experiments for the binary systems of brine/carbonated brine (CB), carbon dioxide (CO2) and live and dead crude oils were performed. The experiments done using the axisymmetric drop shape analysis (ADSA) technique at temperatures of 40 °C and 50 °C and different pressures up to 13.79 MPa. The IFT results are used to estimate and determine optimum value of spreading coefficient, which is known as a key enhanced oil recovery (EOR) parameter at the pore scale. The experimental results demonstrate that CB decreases the equilibrium IFT of crude oil compared to the brine at the same conditions (for example, the difference of IFT is 5.2 mN/m and 7.6 mN/m at temperature of 40 °C and pressures of 2.76 and 13.79 Mpa, respectively). The equilibrium IFT of the live oil-brine/CB system is greater than that of dead oil-brine/CB. The estimated SC shows that the presence of CO2 in the aqueous phase significantly affects the SC value. That is, it becomes positive for the dead/live oil-CB-CO2 system, and improve the performance of EOR process while it is negative for the dead/live oil-brine-CO2 system. The presence of CH4 gas in the oil phase reduces the SC values at different pressure conditions. Moreover, using the SC results are determined the optimum conditions during CWAG injection. Based on the observed results in the dead/live oil-CB systems, swelling phenomena of the dead oil drop be slightly lower than that of the live oil drop.