Heavy oil reservoirs form one of the primary unconventional fossil fuel resources to meet the growing demand for global energy. Hydrocarbon recovery yields from these reservoirs is often low or requires energy intensive thermal processes. For instance, in the case of waterflooding in heavy oil reservoirs, high oil viscosity results in early breakthrough and poor sweep efficiencies. Polymers have been used to increase the displacing water viscosity for conformance control and viscous fingering attenuation. However, polymer degradation and entrapment inside the reservoir make them less attractive. Recent experiments using conventional oil samples showed that the incorporation of silica nanoparticles in the injected solution (i.e. nanofluid) can dramatically enhance oil production. Nanofluids are more stable than polymers in harsh reservoir conditions, also they can modify the interfacial properties between oil and water, and thereby nanofluids may provide capabilities for heavy oil recovery.
In this study, a microfluidic platform was utilized to monitor the process of nanofluid-based heavy oil recovery for a representative Alberta heavy oil sample. To create a reference, recovery experiments were repeated with waterflooding and surfactant flooding process. Consistent with coreflood experiments for conventional oil samples, nanofluid injection increases the oil recovery compared to the waterflooding. Microscale visualization revealed that emulsion formation during heavy oil displacement with chemicals is the main factor in incremental recovery.
The developed microfluidic approach is a powerful mimetic model for the real-time visualization of the chemical-based heavy oil recovery process in micro/nano scale. Considering the time-consuming and expensive nature of coreflood experiments, this method provides an attractive alternative for rapid and low-cost chemical-enhanced oil recovery (EOR) screening studies. Results demonstrate the strength of nanofluid-EOR as an efficient recovery method for Alberta heavy oil reservoirs.