Adaptability of Low Molecular Weight Salt-Resistant Hydrophobic Associating Polymer in Low Permeability Reservoir

B3 block of Changqing Oilfield has low reservoir permeability and high salinity formation water. In order to solve the problems of poor injection and salt resistance of conventional polymers and further improve the development effect of polymer flooding, the adaptability of low molecular weight anti-salt hydrophobic associating polymers in this test area is studied. The viscosity, salt resistance, shear resistance, adsorption resistance and aging stability of the polymer were measured by laboratory experiments. The experimental results show that compared with polyacrylamide and functional polymer, the low molecular weight salt-resistant hydrophobic associating polymer has better salt resistance, shear resistance and stability. The viscosity of 2000 mg/L polymer is 28 mPa·s at 50 ℃ and 13600 mg/L mineralization (572 mg/L calcium and magnesium ion concentration). The core with 70–80 mD permeability was used for oil displacement experiments. The results showed that the viscosity retention rate of polymer flooding solution reached 80%, and the oil displacement efficiency can be improved by 14.8% on the basis of water flooding.