Influence of Polymer Retention on Non-Newtonian Flow in Porous Media

This paper reports the results of an experimental study aimed at analyzing the effect of polymer retention on flow behavior in porous media. Using 6 partially hydrolyzed polyacrylamides (PAAm) and a vinylamide, acrylamide and vinylsulfonate copolymer (VAVS), core flow tests were performed to quantify the effect of polymer retention on viscoelastic effects of polymer solution in porous media. To achieve the maximum efficiency of polymer solutions, experimental conditions of core flood tests were optimized. From the experimental results, it appears thai the maximum retention increases with increasing polymer concentration, flow velocity and also with decreasing core permeability. It is also influenced by the hydrolisation degree of polyacrylamides in the same manner as the hydrodynamic radii (rh), intrinsic viscosity (n) and overlap concentration (C*) of polymers. To quantify the viscoelastic effects in porous media, the concept of the critical Deborah-number and the onset and maximum of shear thickening in terms of two critical flow rates were applied. It was found that, the transitions from Newtonian flow via shear thinning into shear thickening shifts to lower flow rate with increasing polymer retention and with increasing core permeability. Practical information is provided on the critical flow rates, magnitude of shear thickening and their dependency on hydrolysis degree of PAAm and polymer retention.