Temperature- and Salt-Tolerant 2-Acrylamide-2-methylpropanesulfonic Acid/AM@SiO2 Microgel Particles: Synthesis and Enhanced Oil Recovery Performance Evaluation

To simultaneously meet the demands of small size for easy transportation and injection as well as temperature and salinity resistance, 2-acrylamide-2-methylpropanesulfonic acid (AMPS)/AM@SiO2 microgel particles were synthesized to achieve a good performance for the in-depth profile control treatment. The characteristic functional group, mechanical property, and enhanced oil recovery (EOR) performance were comprehensively evaluated by Fourier infrared spectrometer, nanoindentation apparatus, and sand-packed tubes with different permeability conditions. AMPS contains active double bonds and sulfonic acid groups, which could enhance the temperature and salinity resistance of gel systems. Therefore, the AMPS/AM and AMPS/AM@SiO2 microgel particles have remarkable temperature and salinity tolerance and can be used at a high temperature (130 °C) and high salinity conditions (200,000 mg/L). The mechanical energy can be dissipated effectively by adding 1.0 wt % nano-SiO2 which could significantly improve the compression strength and elastic modulus. The elastic moduli of the AMPS/AM@SiO2 microgel particles (1500 mg/L) are 17.36 MPa, which is much higher than that of AMPS/AM microgel particles (10.44 MPa). This effect can improve the performance of the antierosion and compression deformation of the AMPS/AM@SiO2 microgel particles. The AMPS/AM@SiO2 microgel particles not only have good plugging performance and antierosion stability that can divert the subsequent injected fluid to lower permeable zones but also can achieve an in-depth secondary plugging effect through compression deformation and remigration. The performance of profile control and oil displacement of the AMPS/AM@SiO2 microgel particles has been verified from parallel sand-packed tubes simulating strong heterogeneous reservoirs. Compared with water flooding, the total oil recovery was increased by 22.8% after the injection of 0.5 PV AMPS/AM@SiO2 microgel particles, which is higher than that of AMPS/AM microgel particles (16.4%). This work not only provides a potential agent, i.e., AMPS/AM@SiO2 microgel particle, for in-depth profile control in high temperature and high salinity offshore oilfields but also helps for a better understanding of the mechanism of in-depth profile control and EOR for microgel particles.