Adsorption of Linear Flexible Polymers During Laminar Flow Through Porous Media:

Abstract

Abstract Polymer solutions for water control are usually injected at a relatively high concentration (i.e. the semi-dilute regime). During placement entangled polymer chains can be retained by a collective adsorption and bridging mechanism. This results in polymer loss near the face of the wellbore and in an inefficient reduction of water relative permeability. The data on the effect of collective adsorption of entangled chains are scarce in literature. In this experimental study we are concerned with the influence of polymer concentration and permeability on the retention of high molecular weight non-ionic polyacrylamide (PAAm) during flow in granular porous media (packing of silicon carbide). Thus far we have made the following observations. At low polymer concentrations (the dilute regime) polymer injection leads to a gradual increase in pressure drop. Finally the pressure drop levels off to a plateau indicating steady-state flow. It is known that the delay in the polymer displacement front is related to the amount of adsorbed polymer. At higher concentrations (semi-dilute regime), however, no steady state flow seems to be reached within the duration of the experiments. Furthermore the residual flow resistance, determined by water flow following polymer, increases with polymer concentration. These effects can be explained by a mechanism of collective retention of entangled chains, which are adsorbed and bridge over pore constrictions. P. 225