Water Permeability Reduction Under Flow-Induced Polymer Adsorption

摘要

The influence of induced polymer adsorption for reducingrnthe effective permeability to water in reservoirs wasrninvestigated. Results for the anionic polymer used in thisrnstudy, show that polymer adsorption is unaffected by the ionicrncharacter of polymers, provided the polymer is hydrophilic.rnIn this paper, we present experimental results that show atrnincreased shear rates, there is improvement in the adsorbedrnpolymer layer. This phenomenon is known as flow-inducedrnadsorption. These experiments indicate that above a criticalrnshear rate, there is a shift in permeability-reductionmechanismrnfrom static to flow-induced adsorption,rnnecessitating a sharp increase in adsorbed polymer layer.rnDifferent scenarios to investigate the effect of polymerrnresidence time and increasing rate of brine flush wererninvestigated. Results show that there is a marked difference onrnwater permeability reduction at zero polymer residence timernand when a polymer residence time is allowed. Under staticrnadsorption, slight increase in adsorbed layer thickness at lowrnshear rates is observed. This effect is induced during brinernflush when polymer macromolecules are forced to penetraternthe existing adsorbed polymer layer. This results in maximumrnconformance of the polymer macromolecules at low shearrnrates, contributing significantly to the influence of flowinducedrnadsorption, depending on the rate of brine flow. Allrnthe experimental results revealed that the critical shear rate forrnthis polymer is between 400 to 500 s-1 in the absence ofrnmechanical degradation. For comparison with the abovernexperimental results, similar experiments were performed atrnincreased polymer concentration and also carried out in a core.rnResults indicate that the permeability-reduction-mechanism isrnconstrained by increased polymer concentration and lowpermeabilityrnporous media.