Pore-scale Visualization of Polymer Viscoelasticity Using Particle Tracing in Glass-Silicon-Glass Micromodels

This paper investigates and discusses the latest topic related to polymer viscoelasticity - elastic turbulences - during EOR polymer process application by using Glass-Silicon-Glass micromodels that resemble porous media. Experimental characterization of flow regimes was performed at a pore scale level by using aqueous partially hydrolyzed polyacrylamide (HPAM) solutions with a tracer attached, compared to a low-salinity brine (4 g/l). A strong influence of salinity, HPAM concentration and polymer’s mechanical degradation conditions on the viscoelasticity and thereby on elastic turbulence was observed. Pore space geometry and flow rate also affected the flow regime of polymer solutions. At a certain flow rate, viscoelastic polymer solutions showed the onset of elastic turbulence (known so far as shear thickening behavior) whereas the non-viscoelastic Newtonian brine showed a completely laminar flow pattern. During polymer flooding in micromodels, different regions are observed. (1) A zone mainly characterized by laminar flow in case of brine, (2) vortices mainly created in coves (3) and crossing streamlines especially in the wall areas. Moreover, a clear correlation between elastic turbulence at pore-scale and characteristic relaxation time was found, which provides new insights into the fundamental understanding of polymer behaviour at pore scale level during chemical EOR reservoir processes.