Difference Analysis of Polymer Injection under Constant Velocity and Pressure Conditions

Abstract

In the later stage of polymer flooding, in order to achieve high polymer recovery, high polymer flooding is started. Before injection, it is necessary to clarify the difference of polymer model with constant velocity or constant pressure, and provide technical support for the smooth polymer injection. Under the condition of constant velocity and constant pressure, the injection process of polymer solution was simulated and compared with the criterion of injection capacity in two cases. Furthermore, the applicable scope of polymer injection with constant velocity and constant pressure was further clarified. The test shows that, (1) at constant speed under the condition of 0.2ml/min, 16 million and 25 million molecular polymers can’t be injected into layer of 200×10-3µm2 permeability. (2) In cores of 200×10-3µm2 permeability, polymer is injected at 0.1 and 0.15 MPa/m under the condition of constant pressure, according to the experimental results, the recommended flooding concentration is 1000 ∼ 1500mg/L (16 million molecular), 1000mg/L (25 million molecular). (3) In cores of 300×10-3µm2 permeability, in addition to the 2000mg/L velocity injection of 25 million polymers, the injection of other molecules with constant velocity or constant pressure is successful, and all of them are available. (4) in short, in cores of 200×10-3µm2 permeability, constant pressure injection. Polymer can be injected smoothly under the condition of low polymer concentration, compared to constant speed under the condition of difficult injection / jam, constant velocity injection has more advantages to select more improve polymer injection methods. This study can provide technical support for polymer flooding mode selection in the late stage of polymer flooding.