Experimental Study on Water-Plugging Performance of Silicon Dioxide/Polystyrene Hydrophobic Insoluble Microsphere Particle Flooded by High-Water-Cut Oil–Water Mixture

Water plugging was an important but difficult process close to high-water-cut production wells. The injected water-plugging materials were usually liquid and typically had been evaluated by conventional water-flooding experiments. In this study, silicon dioxide (SiO₂)/polystyrene hydrophobic insoluble microsphere particles were introduced as a selective water shutoff agent, and the water-saturated core was flooded with a high-water-cut oil–water mixture. Indexes such as modified oil-coning time, water-cut fluctuation, and cumulative water cut were proposed to evaluate water-plugging capability. A parametric study was conducted to evaluate the influence of particle composition (A, SiO₂/polystyrene particle; B, complete polystyrene particle), water cut of the injected oil–water mixture, and preheating temperature of the insoluble particles on water-plugging performance. The results from the index analysis and relative permeability curve showed that the proposed indexes could be used to compare water-plugging performance during oil–water mixture drive; both particles had better water-plugging performance when the injected mixture was not an ultrahigh water cut (f_w < 90%). Particle B had larger lipophilicity and stronger capacity for decreasing the water cut (about 0.55–1.28%) at a conventional temperature when the oil–water mixture of the injected fluid had a water cut of 90%. Particle A had lower capacity to decrease the water cut (by about −0.94–0.26%), but it was resistant to reservoir temperature because of its dense structure and the addition of SiO₂. These results provided suggestions for the application of hydrophobic insoluble microsphere particles in water plugging in production wells.