Dynamic Variation of Rheological Behavior and Displacement of Polymer Flooding in Mid-Low Permeability Cores

Abstract

On artificial long cores with multiple measuring points and standard cores, laboratory experiments were carried out for the rheological behavior and oil displacement capability of polymer (HPAM) solution with mass concentration of 1500 mg/L. The relative molecular mass of polymer was 1200 × 104. The pressure and oil saturation distribution were analyzed by using the numerical model. The results indicated that the rheological behavior of polymer solution was shear thinning and shear thickening. Moreover, the longer the migration distance was, the narrower the shear rate range was, and the smaller the critical shear rate was. The maximum injection pressure was 5.67 Mpa, and the stable value was 5.21 Mpa when injected the polymer solution into the cores with permeability of 50 × 10−3 μm2 and length of 85 cm. The resistance coefficient of inlet and outlet was stable at 185 and 6, respectively, which indicated that the polymer solution was blocked at near area of inlet and the oil displacement capacity was limited at near area of outlet. The oil recovery of polymer flooding was increased 8.9% point compared with that of water flooding when injected 0.3 PV polymer solution into the standard core after the water cut reached 70%. The variation with the migration distance of rheological behavior and the oil displacement capacity of polymer solution was important for further study on the matching of low permeability reservoir with the polymer solution.