Abstract

Viscous fingering is a major obstacle to successful waterflooding in heavy oil reservoirs, as it results in water breakthrough and an undeveloped oil bank. To overcome viscous fingering, the composition of injected fluid can be tailored to a production scheme which optimally enhances oil recovery. Smart water can improve oil recovery through wettability alteration. However, wettability alteration also leads change in mobility ratio, which depending on value, may have either a negative or positive impact on oil recovery and water production and must therefore be carefully controlled.

In this study, smart waterflooding outperforms conventional waterflooding regarding oil recovery, with incremental recovery reaching as high as five percent. Moreover, smart waterflooding also significantly decelerates the water cut (WCUT) trend by subduing the effect of viscous fingering and decreasing the water relative permeability. Our results show that reducing a salinity of the injected fluid allows mineral dissolution reactions to raise effective permeability compared to that achieved by conventional waterflooding. Injection and production pressure affect mineral dissolution/precipitation and, consequently, effective porosity and permeability. Numerical simulation is used to analyze the potential of smart waterflooding as an enhanced oil recovery method in heavy oil reservoirs.

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