Does Non-circular Shear Rheometry Amplifies the Nonlinear Viscoelastic Effects for an Improved Polymer EOR Selection Criteria?

Steady-shear rheometry equipped with the perfect circular geometry has been used for decades to characterize the viscous characteristics of EOR polymer systems. Recently (Azad in SPE J, 2023), they have been successfully used to characterize the shear thickening characteristics of higher Mw (molecular weight)-higher elastic polymer systems. However, circular geometry fails to thicken the low Mw-lesser elastic polymer systems that exhibited thickening in consolidated porous media. Despite the fact that the different geometries could impose a different deformation, no effort was made to study the effect of non-circular geometry on their rheological behavior. This paper addresses this gap. The results indicate that non-circular geometry not only thickens the higher Mw-elastic systems strongly, but also the lower Mw-lesser elastic systems. Compared with concentric cylinder (CC) geometry, non-circular geometry better predicts the nonlinear viscoelastic properties of polymer systems especially those characterized by low Mw-low salinity-high concentration in porous media. However, CC appears to characterize the Newtonian behavior well and thereby suggests that the combination of both geometries could improve the selection criteria for viscoelastic polymer EOR applications.