With continued water injection development, most oilfields have entered high and ultra-high water-cut stages. To address the issue of poor thermal and salt resistance in conventional polymer flooding systems, a salt-tolerant amphiphilic polymer-based supramolecular inclusion system was developed, incorporating a surfactant as a synergistic agent to reduce oil–water interfacial tension (IFT) and further increase system viscosity. In this study, viscosity and oil–water interfacial tension were used as evaluation indicators to optimize the formulation of the surfactant synergistic enhanced inclusion system. The effects of factors such as temperature, inorganic salts, and pH on the apparent viscosity and interfacial tension of the system were systematically examined. Dynamic light scattering and a one-dimensional core physical model were employed to study the emulsification performance and oil displacement efficiency of the system. The results indicate that the surfactant synergistic enhanced inclusion system exhibits excellent thickening ability and IFT reduction under high-temperature and high-salinity conditions (85 °C, 20 × 104 mg·L−1). The rheological properties and IFT reduction capability of the system are both pH-responsive, with optimal performance observed in neutral to alkaline conditions, suggesting a broad application range. The surfactant synergistic enhanced inclusion system not only reduces the water cut but also improves oil-washing efficiency through emulsification, achieving an ultimate recovery rate of 60.13% with an enhanced oil recovery (EOR) of 24.75%. These findings demonstrate that this system is a promising alternative for enhancing oil recovery in high-temperature and high-salinity reservoirs.

Polymer microspheres represent a novel oil displacement agent that has demonstrated significant efficacy in oilfields. Recent research indicates that the viscoelastic properties of polymer microspheres are crucial for oil displacement. To further elucidate the viscoelastic displacement mechanism, a series of fluorescent polymer microspheres, P(AM-BM-AA-[Br−Flu]), with varying elasticity were synthesized via inverse suspension polymerization, incorporating fluorescent monomers derived from fluorescein (Br−Flu). The micromorphology and viscoelastic properties were systematically characterized using an infrared spectrometer, scanning electron microscope, inverted fluorescence microscope, laser particle size analyzer, and rheometer. Through microscopic and macroscopic oil displacement experiments, along with microsphere concentration tests, the viscoelastic displacement mechanism of polymer microspheres was investigated. The results indicate that P(AM-BM-AA-[Br−Flu]) exhibiting green fluorescence was successfully synthesized. By adjusting the crosslinker concentration, polymer microspheres with different elasticities were produced. During the displacement process, the elasticity of the microspheres governs their migration mode within the pore throats. Microspheres with higher elasticity exhibit greater sweep efficiency. The pushing and carrying effect of microspheres on residual oil droplets, the positive pressure breakthrough effect resulting from microsphere trapping, and the displacement of blind-end residual oil collectively enhance the oil displacement efficiency of microspheres. From a force analysis perspective, the elasticity of microspheres plays a pivotal role in improving both sweep efficiency and oil displacement efficiency. These findings provide experimental support for understanding the oil displacement mechanisms of polymer microspheres and for developing new polymer microsphere-based oil displacement agents.