Enhanced oil recovery from carbonate reservoirs by spontaneous imbibition of low salinity water

Abstract

An experimental study was performed to investigate the impact of low salinity water on wettability alteration in carbonate core samples from southern Iranian reservoirs by spontaneous imbibition. In this paper, the effect of temperature, salinity, permeability and connate water were investigated by comparing the produced hydrocarbon curves. Contact angle measurements were taken to confirm the alteration of surface wettability of porous media. Oil recovery was enhanced by increasing the dilution ratio of sea water, and there existed an optimum dilution ratio at which the highest oil recovery was achieved. In addition, temperature had a very significant impact on oil recovery from carbonate rocks. Furthermore, oil recovery from a spontaneous imbibition process was directly proportional to the permeability of the core samples. The presence of connate water saturation inside the porous media facilitated oil production significantly. Also, the oil recovery from porous media was highly dependent on ion repulsion/attraction activity of the rock surface which directly impacts on the wettability conditions. Finally, the highest ion attraction percentage was measured for sodium while there was no significant change in pH for all experiments.

Impact of water saturation and cation concentrations on wettability alteration and oil recovery of carbonate rocks using low-salinity water

“…They optimized the dilution of sea water for maximum oil recovery in low-salinity sea water imbibition. The results indicated that the 20 times diluted sea water could recover more oil in comparison with the other studied concentrations (Zaeri et al 2018).…”

“…In our previous study, experiments were performed to obtain the optimum salinity of brine. The results showed that the 20 times diluted sea water recovered the maximum amount of oil in the imbibition tests (Zaeri et al 2018); consequently, in this study, the 20 times diluted sea water is used to investigate the impact of initial water saturation and rock type at the optimum salinity of injected brine and adsorption-desorption of cations.…”

“…The low-salinity water injection is more efficient for the crude oils that contain higher acidic and polar components (Hadia et al 2012;Shaddel and Tabatabae-Nejad 2015). • The amount of connate water saturation in the rock can change the oil recovery during low-salinity flooding which causes recovery factor enhancement in the case of sandstone samples (Zhang and Morrow 2006;Viksund et al 1998 (Shehata and Nasr El-Din 2015;Zhang et al 2007;Schembre et al 2006;Tang and Morrow 1997a;Zaeri et al 2018). • The type of ions (and charges of them) in the injected brine and resident brine have a significant impact on the oil recovery during low-salinity water injection.…”

Smart water flooding performance in carbonate reservoirs: an experimental approach for tertiary oil recovery

“…Derjaguin-Landau-Verwey-Overbeek (DLVO) theory is implemented for detachment of fine particles in LSWF, and fine detachment takes place whenever the injected brine salinity is lower than or equal to the critical flocculation concentration (Lager et al 2006). Additionally, rock dissolution is a possible mechanism for enhanced oil recovery toward low-salinity water flooding (Lager et al 2006;Pu et al 2010;Zaeri et al 2018a). Moreover, anhydrite dissolution in sea water injection leads to in situ sulfate ion generation; hence, the wettability would be altered (Yousef et al 2012).…”

“…Additionally, rock dissolution is a possible mechanism for enhanced oil recovery toward low-salinity water flooding (Lager et al 2006;Pu et al 2010;Zaeri et al 2018a). Moreover, anhydrite dissolution in sea water injection leads to in situ sulfate ion generation; hence, the wettability would be altered (Yousef et al 2012).…”