Migration And Plugging Characteristics Of Microspheres And Polymer Solutions In Reservoir Models

The contradiction between migration and plugging of microspheres and polymer solutions in reservoirs is the key to affect the effect of deep performance control.In order to solve this problem,the injection and plugging properties of B-PPG microspheres and polymer HPAM solution in reservoir model are studied by using micro-pore throat model and core simulation model.Through the migration characteristics experiments of microspheres and polymers in a single-hole throat model,it is recognized that the migration resistance of microspheres in a single-hole throat model increases as the ratio of microspheres diameter to throat diameter(Grain throat ratio)increases.The migration resistance of microspheres in the single-pore throat model increases slowly with the increase of the grain throat ratio in the range of 6-12.When the grain throat ratio exceeds 18,the migration resistance of microspheres in the single-pore throat model increases rapidly.When the concentration of microspheres is less than 2000mg/L,the migration resistance of microspheres increases slowly with the increase of the concentration of microspheres;when the concentration of microspheres is more than 2000mg/L,the migration resistance of microspheres increases rapidly with the increase of the concentration of microspheres.The migration resistance of polymer in pore throat increases with the increase of solution concentration;when polymer concentration is less than 3000mg/L,the migration resistance of polymer in single pore throat model increases rapidly with the increase of concentration;when polymer concentration is higher,the resistance of polymer injection pore throat increases slowly with the increase of concentration.When the polymer concentration is more than 3000mg/L,the migration resistance of the polymer in the single pore throat model increases slowly with the increase of the concentration.A microsphere-like dispersion medium cannot be used as a continuousmedium in the pore throat,and its hydrodynamic behavior cannot be characterized by viscosity characterization.Through the experiments on the diversion rate of microspheres and polymers in the parallel pore throat model,it is recognized that both microspheres and polymers have selectivity to plug the large pore throat in the parallel pore throat model;the higher the concentration,the better the plugging ability of microspheres and polymers to the large pore throat;the larger the ratio of two throat diameters(throat diameter ratio)of parallel pore throat model,the stronger the ability of microspheres to adjust diversion rate of pore throat model.In the parallel pore throat model with smaller throat diameter,the polymer has a certain plugging capacity and selectivity for large pore throat,and can adjust its diversion rate.In the parallel pore throat model with larger throat diameter,the effect of polymer on adjusting diversion rate is obviously reduced.Through microsphere and polymer core experiments,it is recognized that in the medium-high permeability core,resistance coefficient for characterizing microsphere injectability is low,and residual resistance characterizing the plugging capacity gradually increases along the migration direction.This microsphere has the necessary conditions for reservoir deep performance control.The higher the concentration of the microspheres,the larger the residual resistance coefficient and the stronger the blocking ability.Resistance coefficient of the polymer solution in medium-high permeability core is obviously higher than that of the microsphere,and the injection property is relatively poor.Residual resistance coefficient characterizing the plugging ability is sharply attenuated along the migration direction.The blocking capacity formed in the deep part of the reservoir is very weak,and it does not have the necessary conditions for deep profile control of the reservoir.The results of profile control experiments in heterogeneous cores indicate that the injection of equal amounts of microspheres and polymer solution,the microspheres increase the recovery factor by 16.72%,and the injection polymer improves the recovery factor by 7.28%.It is obvious that the microspheres have a significantly better oil displacement effect than the polymer.