Xin Mengke, Zhang Dingxue, Zhang Yan, Chen Jun, Yan Linshuo, Qin Yiwei, Zhang Qirui
School of Petroleum Engineering, Yangtze University, Wuhan, Hubei, China.
Key Laboratory of Drilling and Production Engineering for Oil and Gas, Hubei Province, Wuhan, Hubei, China.
PLoS One. 2025 Aug 29;20(8):e0326805. doi: 10.1371/journal.pone.0326805. eCollection 2025.
Low-permeability reservoirs, characterized by poor reservoir quality and pronounced heterogeneity, consistently encounter engineering challenges during waterflooding operations, such as suboptimal displacement efficiency and restricted sweep coverage. Nanoemulsions, through wettability alteration and enhancing macroscopic sweep efficiency, are widely applied in the efficient development of low-permeability reservoirs. However, current field applications in Reservoir G exhibit inefficacy, necessitating laboratory experiments to identify factors affecting poor injection performance and enhance oil recovery. This study conducted laboratory core displacement experiments using native cores from the target reservoir, integrated field operational data for injection parameter optimization, and implemented field applications. Results indicate: (1) The modified nano-SiO₂ emulsion, with an average particle size of 26.01 nm, is substantially below the pore-throat dimensions of reservoir cores; (2) Wettability reversal was confirmed through contact angle reduction on oil-wet substrates from 132.9° to 53.6°; (3) Optimal parameters-0.1 mL/min injection rate, 0.3 wt% concentration, and 0.3 PV slug volume-Utilizing dual-slug injection (0.15 PV × 2 + 0.1 PV water spacer) enhanced oil recovery by 18.83%. Segmented injection effectively mitigates particle adsorption-induced plugging and achieves deep reservoir penetration, outperforming single-slug injections. Field experimental results show that segmented injection with water spacers increased daily fluid production from 2.86 m³ to 5.22 m³ and daily oil production from 2.23 t to 4.3 t, retaliating a synergistic mechanism of the modified nano-SiO₂ emulsion in "performance-parameter-mode" optimization.
低渗透油藏具有储层质量差和非均质性显著的特点，在注水作业过程中一直面临工程挑战，如驱替效率欠佳和波及范围受限。纳米乳液通过改变润湿性和提高宏观波及效率，被广泛应用于低渗透油藏的高效开发。然而，目前在G油藏的现场应用效果不佳，需要进行室内实验以确定影响注入性能不佳的因素并提高采收率。本研究使用目标油藏的天然岩心进行了室内岩心驱替实验，整合现场作业数据以优化注入参数，并开展了现场应用。结果表明：（1）改性纳米SiO₂乳液的平均粒径为26.01 nm，远低于油藏岩心的孔喉尺寸；（2）通过将油湿基质上的接触角从132.9°降低到53.6°，证实了润湿性反转；（3）最佳参数——注入速率0.1 mL/min、浓度0.3 wt%、段塞体积0.3 PV——采用双段塞注入（0.15 PV×2 + 0.1 PV水段塞）可提高采收率18.83%。分段注入有效减轻了颗粒吸附引起的堵塞，并实现了油藏深部穿透，优于单段塞注入。现场实验结果表明，带水段塞的分段注入使日产液量从2.86 m³增加到5.22 m³，日产油量从2.23 t增加到4.3 t，验证了改性纳米SiO₂乳液在“性能-参数-模式”优化中的协同机制。
