Oil Recovery Analyses and Formation Water Investigations for High Salinity-Low Salinity Water Flooding in Sandstone Reservoirs

Recently, we investigated the effect of Ca2+ in the formation water and its potential on low salinity (LS) water flooding (Al-Saedi et al. 2018). In this paper, we pursue to quantify the influence of formation water containing Ca2+ and Mg2+ on LS EOR. Berean sandstone cores were sequentially flooded with high salinity HS water and LS water at 90°C. During injecting brines, samples of the effluent were analyzed for pH. Oil recovery experiments with a double Ca2+ and 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 Ca2+ and Mg2+ in the HS water was decreased by half. The results of this work isolate and relate oil recovery with the most effective factors that control LS water chemical mechanisms.