Simulation study of wettability alteration by deep eutectic solvent injection as an EOR agent for heavy oil reservoirs

• Simulation of DES injection was conducted as an EOR agent for heavy oil reservoirs.
• Effect of DES on the oil/brine/rock interaction in the porous media was investigated.
• Wettability alteration is the main factor yielding to enhance heavy oil recovery via DES.
• Injecting DES1 and DES2 reduced mobility ratio compared to water flooding.
• DESs showed better performance as tertiary recovery than secondary recovery.

In this study, simulation of enhancing heavy oil recovery via deep eutectic solvent (DES) injection was conducted. Several coreflooding tests have been completed and modelled to study the effect of DES injection on the interactions of oil/brine/rock in the porous media. The performance of the Choline Chloride: Malonic acid mixture at two molar ratios of 1:1 and 2:1 as DES1 and DES2, respectively, were studied.Results indicated that wettability alteration from weakly water-wet towards more water-wet and mixed-wet conditions was the dominant reason for the reduction of residual heavy oil saturation. DESs injection resulted in favourable and lower mobility ratio compared to the conventional waterflooding. At 45 °C, mobility ratio reduced by 26% in DES1 and 25.5% in DES2 compared to the waterflooding. Further increase in temperature up to 80 °C led to reduction in mobility ratio by 84.8% and 62.2% for DES1 and DES2, respectively. Hence, temperature found to be a key parameter in application of DES chemical methods in the field applications. The study also showed that DESs display better performance as a tertiary recovery rather than the secondary approach.Our experimental and simulation studies showed the potential application of DESs as cheap, non-toxic, recyclable, biodegradable and environmentally friendly chemicals for the EOR field applications.