Interaction of elasticity and wettability on enhanced oil recovery in viscoelastic polymer flooding: A case study on oil droplet

The complex distribution of residual oil, influenced by wettability and low sweep efficiency, presents significant challenges to its effective mobilization. Polymer flooding can increase microscopic sweep efficiency by elastic effect. Despite both elasticity and wettability can achieve enhanced oil recovery, current study of the interaction of elasticity and wettability is still not well understood. In this regard, we further investigate their interaction in improving oil recovery by using simplified oil droplet model. The secondary development of the interFoam solver in OpenFOAM is employed. The simulation results indicate that the initial deformation of oil droplet is not influenced by elastic forces, while by viscous forces. Furthermore, oil displacement efficiency of oil droplet, at strong water-wet condition, increases from 65.61 % to 69.06 % as elasticity (We) increases from 0.1 to 50. This reveals that elasticity promotes oil droplet displacement at water-wet. In contrast, oil displacement efficiency at weak oil-wet decreases from 15.53 % to 11.55 %, which reveals that elasticity inhibits the deformation and flow at oil-wet. Moreover, as elasticity increases, the direction of normal stresses varies from the same as flow direction (strong water-wet), to being an angle to flow direction (weak oil-wet), then to being opposite to flow direction (strong oil-wet). These findings can advance the understanding of the micro-flow mechanisms involved in viscoelastic polymer flooding.