Experimental study of in-situ W/O emulsification during the injection of MgSO₄and Na₂CO₃ solutions in a glass micromodel

In-situ emulsification of injected brines of various types is gaining increased attention for the purpose of enhanced oil recovery. The impact of injecting various solutions of Na₂CO₃ and MgSO₂ at different flow rates resembling those in the reservoir and near wellbore using a glass micromodel with different permeability regions was studied. Emulsification process was visualized through the injection of deionized water and different brines at different flow rates. The experimental results revealed that the extent of emulsions produced in the vicinity of the micromodel exit was considerable higher than those at the entrance of the micromodel. The injection of Na₂CO₃ brine after deionized water caused the impact of emulsification process more efficiently for attaining higher oil recovery than that for the MgSO₄₂ brine. For instance, the injection of MgSO₂ solution after water flooding increased oil recovery only up to 1%, while the equivalent figure for Na₂CO₃ was 28%. Lower flow rate of injection caused the displacement front to be broadened since the injected fluid had more time to interact with the oil phase. Finally, lower injection flow rate reduced the viscous force of the displacing fluid which led to lesser occurrence of viscous fingering phenomenon.