Magnetic Responsive Pickering Emulsion Containing SiO<sub>2</sub>–Fe<sub>3</sub>O<sub>4</sub> Particles with Highly Selective Water Plugging in High-Salt Reservoirs
Xiaofeng Xing, Zhiyin Zhao, Dongmei Yang, Jie Wen, Hui Zhang
Abstract
The development of selective water-plugging materials is a challenging task in oil field research. A magnetically responsive emulsion containing SiO 2 –Fe 3 O 4 particles was prepared using the mechanical emulsification method. The stability, magnetic demulsification, and water-plugging performance of the emulsion were evaluated. The results showed that the emulsion with SiO 2 –Fe 3 O 4 particles could maintain stability for up to 30 days at room temperature. However, when the temperature exceeded 80 °C, the thermal stability decreased with an increase in the SiO 2 –Fe 3 O 4 ratio. Meanwhile, based on the magnetic response of Fe 3 O 4 particles, the demulsification behavior of the emulsion under a constant magnetic field strength was analyzed, revealing that the stability of the emulsion is jointly determined by the particle membrane and surfactant. Results from the displacement experiments showed that when the water phase plugging rate reached more than 97%, the oil phase plugging rate was only 45%. Mechanism analysis and contact angle characterization verified that the plugging rates for the water and oil phases depend on the cross-linking form of the SiO 2 –Fe 3 O 4 composite material. Fe 3 O 4 particles “wrapping” around SiO 2 particles are beneficial for enhancing water-plugging performance.