Experimental Investigation of the Performance of Low Salinity Water Flooding at High Temperature

The potential of divalent cation Mg²⁺ in formation water (FW) for low-salinity (LS) EOR effect was previously investigated [Al-Saedi et al. in Oil recovery analyses and formation water investigations for high salinity-low salinity water flooding in sandstone reservoirs. SPE, 190845, 2018 1], where the increase in divalent cations in FW lowered the effect of LS water. In this study, we studied the importance of the same divalent cation (Mg²⁺ only) in the injected water. Berea sandstone cores were successfully flooded with FW and LS water at 130 °C. While injecting both brines, samples of the effluent were analyzed for pH. Oil recovery experiments with a double Mg²⁺ concentration showed a lower LS water effect, meaning that the cores became more water-wet; however, the LS water effect was much greater when the amount of Mg²⁺ in the HS water was decreased by half.