CO2-Responsive Polymer Microspheres for Controlling CO2 Breakthrough in Tight Reservoirs

The development of natural/artificial fractures leads to the intensification of the heterogeneity of tight reservoirs and the difference in the viscosity between CO2 and crude oil, which usually causes serious channeling and low sweep efficiency during CO2 flooding of tight reservoirs. The use of CO2-responsive polymer microspheres to control gas channeling has great potential for improving oil recovery in tight reservoirs. A CO2-responsive polymer microsphere (CRM) was prepared by seed lotion polymerization. FTIR analysis showed that the functional groups of the target microspheres were successfully synthesized; SEM analysis showed that the microspheres were well dispersed and had a wide size distribution; the response swelling property and mechanical shear resistance of CRM were studied. The results showed that CRM was protonated when CO2 was introduced for 10 min, and temperature affected the degree of protonation of CRM. The swelling ratio of CRM in salt water with salinity of 20,000 mg/L was 4.531; the retention rate of particle size of CRM at 10,000 r/min mechanical shear for 30 min is 66.46%. This work can provide feasible candidate materials for tight reservoir development and theoretical support for its application.