Experimental Analysis and Numerical Modeling of Polymer Flooding in Heavy Oil Recovery Enhancement: A Pore-Level Investigation

This study provides new insights into pore-scale displacement events during the simultaneous flow of a low-molecular-weight polymer solution and heavy oil through porous media. Rheological measurements were taken to examine the viscosifying ability of the utilized polymer. The efficiency of the employed solutions in enhancing heavy oil recovery was also investigated using a pore network micromodel. Both macroscopic and microscopic sweep efficiencies were evaluated by analyzing high-resolution pictures continuously captured during the multiphase flow experiments. The rheological measurements revealed that viscosity of the polymer solution is more sensitive to increasing polymer concentration than salinity. Oil recovery experiments disclosed that polymer flooding could yield a recovery factor of about 58% of original oil in-place (OOIP), while the ultimate recovery factor for water flooding is only 35% of OOIP. The macroscopic observations proved that dwindling the formation of viscous fingers during polymer flooding is one of the main responsible factors for the significant improvement of heavy oil recovery. Moreover, the microscopic observations unveiled the noticeable effect of the polymer solution on the enhancement of microscopic sweep efficiency and showed that pulling effects and stripping mechanisms are effective in reducing the saturation of heavy oil at dead ends and pore walls.