Investigation on Profile Control and Flooding Effect of a Microspheres-Surfactant System in Medium-High-Temperature...

To address the issue of poor profile control and displacement effectiveness in medium-high temperature oil reservoirs, a temperature-resistant microsphere-surfactant system (MSS) was developed by combining the advantages of microspheres and surfactants, aiming to stabilize oil production and control water cut. Through static performance evaluation methods, a systematic study was conducted on the particle size distribution, microscopic morphology, high-temperature stability, and hydration swelling properties of polymer microspheres as well as the interfacial tension, emulsifying performance, and temperature resistance of the compound surfactants. Core displacement experiments were used to investigate the dynamic performance of this MSS, including its injectability, blocking performance, and Enhanced Oil Recovery capacity, and the mechanism of the system was analyzed. The results show that the DNM microspheres and the selected Aec9Na + OP-10 surfactant can form a uniformly dispersed system, which maintains good stability after 15 days of aging at 110 °C. After 5 days of hydration swelling, the stable median particle size reaches 5.29 μm, and the particle size remains basically unchanged with prolonged hydration time. MSS exhibits excellent injectability and blocking performance in porous media. The blocking efficiency of MSS gradually increases as the microsphere concentration rises from 0.2% to 0.5%, and 0.4% is optimal in view of injectability. The oil recovery can be improved by 23.33% under a mixed injection mode for the selected system (0.15% Aec9Na⁺0.15% OP-10 + 0.4% DNM). It can block water channeling paths in porous media, divert the subsequent injected water flow, and at the same time reduce the oil-water interfacial tension, alter rock wettability, and enhance the oil displacement efficiency.