Regular Article

Experimental study of in-situ W/O emulsification during the injection of MgSO₄ and Na₂CO₃ solutions in a glass micromodel

¹ Enhanced Oil Recovery Research Centre, Department of Petroleum Engineering, School of Chemical and Petroleum Eng., Shiraz University, Shiraz 71946 85115, Iran
² Institute of GeoEnergy Engineering, School of Energy, Geoscience, Infrastructure and Society, Heriot-Watt University, Edinburgh, UK
³ Institut für Verfahrenstechnik und Umwelttechnik (IVU), Technische Universität Dresden, 01062 Dresden, Germany

^* Corresponding author: mriazi@shirazu.ac.ir

Received: 11 May 2020
Accepted: 7 September 2020

Abstract

In-situ emulsification of injected brines of various types is gaining increased attention for the purpose of enhanced oil recovery. The present experimental study aims at evaluating the impact of injecting various solutions of Na₂CO₃ and MgSO₄ at different flow rates resembling those in the reservoir and near wellbore using a glass micromodel with different permeability regions. Emulsification process was visualized through the injection of deionized water and different brines at different flow rates. The experimental results showed that the extent of emulsions produced in the vicinity of the micromodel exit was profoundly 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 MgSO₄ brine. For instance, the injection of MgSO₄ solution after water flooding increased oil recovery only up to 1%, while the equivalent figure for Na₂CO₃ was 28%. It was also found that lower flow rate of injection would cause 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.