Experimental Investigation of Alkali Flooding on Enhanced Recovery of an Asphaltenic Oil

Among various methods available for chemical enhanced oil recovery, alkaline injection has great potential for production of heavy acidic crudes from oil reservoirs. Through the reaction with acidic components of crude oil, caustic solution reduces the interfacial tension of different existing phases which leads to higher oil production. Besides, asphaltene deposition is a major problem during the production and exploitation from heavy oil reservoirs. The inhibition of asphaltene deposition and proposing a suitable amendatory solution in case of deposition occurrence are significantly important. In this study, the efficiency of alkaline injection on the recovery of crude and synthetic oil solutions was investigated using two different glass micromodels, (i.e. homogeneous and heterogeneous). Furthermore, the effect of alkaline injection in the case of the presence of precipitated asphaltene due to heptane injection was visually observed. Experimental results showed that in crude oils and synthetic solutions, whenever no asphaltene was precipitated, alkaline injection was effective but after asphaltene precipitation, alkaline injection did not have any considerable impacts on oil recovery. The results also demonstrated and authenticated that alkali flooding can alter micromodel wettability in some parts of the model. This wettability alteration mechanism eventually results on enhanced oil recovery.