Synthesis and characterization of novel polymer microsphere with temperature-resistant delayed swelling properties and its application in low permeability reservoirs

Low-permeability oilfields have poor reservoir physical properties, low water-flooding recovery rates, and severe inhomogeneity problems. In this study, a novel temperature-resistant, delayed swelling polymer microsphere was prepared to enhance oil recovery in low-permeability oilfields by introducing the cationic functional monomer DAC and the temperature-resistant monomer NVP. The median particle size of PAADN microspheres was 148 nm and regular spherical. The rheological analysis results show that the polymer microspheres conform to the characteristics of pseudoplastic fluid and have good viscoelasticity. Compared with traditional polymer microspheres, PAADN microspheres have better delayed swelling effect, and the swelling ratio of PAADN microspheres is only 2.9 times at 5 days. In low permeability cores, PAADN microspheres showed better plugging effect and enhanced oil recovery was 18.56%. This study can provide theoretical support for the development of low permeability oilfield.