Experimental and numerical investigation of polymer flooding in fractured heavy oil five-spot systems

Microscopic and macroscopic displacements of polymer flooding to heavy oil at various levels of salinity and connate water saturation have been investigated. Both oil-wet and water-wet conditions in fractured five-spot micromodel systems, initially saturated with the heavy crude oil are utilized. The primary contribution is to examine the role of salinity, wettability, connate water, and fracture geometry in the recovery efficiency of the system. The microscopic results revealed that the increase in the connate water saturation decreases the oil recovery, independent of the wettability conditions. Moreover, the increase in salinity of the injected fluids lowers the recovery efficiency due to the decrease in polymer viscosity. One the other hand, the microscopic results emphasized the wettability role in the simultaneous flow of oil, the connate water, and the polymer phases. In addition, switching from the oil-wet to the water-wet medium has manifested increase in the oil recovery during polymer flooding as compared to water flooding owing to its severe mechanisms of pulling and stripping. To simulate the experimental results, the UTCHEM software has been applied, which has validated the observed data for different fractured patterns, and at various connate water and salinity of polymer solution. Furthermore, the visualized results uncovered a light stripping mechanism in the high permeable fracture. The findings of this study can be beneficial to the better understanding of the microscopic/macroscopic displacements during polymer flooding in fractured heavy oil five-spot systems. It also illustrates the successful application of the UTCHEM for predicting the roles of connate water, salinity and fracture geometry in efficiency of polymer flooding in fractured five-spot micromodels.