Superhydrophobic Mesoporous Silica Nanospheres as Reservoir-Adaptive Smart Plugs for Selectivity Water Shutoff

With increasing water production in mature oil and gas reservoirs, the development of effective water shutoff agents is of critical importance. In this work, a superhydrophobic mesoporous silica (SiO₂)-based water shutoff agent is developed to overcome the limitations of conventional chemical agents under harsh reservoir conditions or to exhibit poor selectivity. To further verify that the mesoporous structure provides advantages over conventional solid nanoparticles in water shutoff, computational simulations are conducted to compare their pressure distributions during the blocking process. The results show that mesoporous particles exhibit higher and broader pressure regions, indicating superior water shutoff performance relative to solid particles. The modified SiO₂ is then prepared into a stable oil-in-water (O/W) emulsion for efficient transport into the reservoir. The characterization results confirm the retention of the mesoporous structure after modification, with a water contact angle of 148.5°, showing excellent thermal and rheological stability. Core flooding experiments demonstrate water shutoff efficiencies of 97.13-99.09% and oil blocking ratios of only 25.00-28.50% in cores with 300-1000 mD permeability under conditions of 100 °C and 35,000 mg/L salinity. These results indicate that the developed system offers a high conformance control performance with robust thermal and salinity tolerance.