改性片状纳米流体的洗油效率及机理

Oil Washing Efficiency and Mechanism of Modified Lamellar Nanofluid

纳米流体提高采收率已然成为油气勘探开发的研究热点。利用研发的改性片状纳米流体,在自制的可视化模型中研究固体界面油膜在接触到质量浓度为50mg/L的改性片状纳米流体后的收缩规律,并开展油砂洗油实验,明确50mg/L的改性片状纳米流体在不同条件下的洗油效率。研究结果表明,模拟地层水环境下,固体界面油膜收缩速率较慢,并未出现楔形区域;改性片状纳米流体环境下,固体界面油膜在收缩过程中出现明显的楔形区域,且出现两条接触线:外接触线和内接触线,外接触线的收缩速率为8.5817×10^(-5)cm/s,内接触线的收缩速率为0.6617×10^(-5)cm/s。油砂洗油实验表明,改性片状纳米流体的洗油效率随油砂尺寸的增大和温度的提升逐渐增加,随着油砂浸泡时间的延长先急剧增加后缓慢上升,存在最佳浸泡时间(8±2)h,油砂洗油效率可高达95.7%。该项研究成果突破了只有高浓度球形纳米颗粒才能形成结构分离压力的限制,为片状纳米流体在矿场的应用提供了可能性,也为矿场施工工艺提供了技术参考。

Nanofluids have become a popular research topic in oil and gas exploration and development due to their potential to enhance oil recovery.the shrinkage behavior of solid-interface oil film was investigated when contacting with 50 mg/L modified lamellar nanofluid in a self-made visualization model.Additionally,oil sand washing experiments were also conducted to determine the oil washing efficiency of the modified lamellar nanofluid at a concentration of 50 mg/L under different conditions.The results showed that the solid-interface oil film shrunk slowly and no wedge-shaped region was observed under simulated formation water condition.However,under the modified lamellar nanofluid environment,the solid-interface oil film shrunk significantly with an obvious wedge-shaped region and two contact lines including an outer contact line and an inner contact line.The shrinkage rate of the outer contact line was 8.5817×10^(-5) cm/s while the shrinkage rate of the inner contact line was 0.6617×10^(-5) cm/s.The results from oil sand washing experiments exhibited that the oil-washing efficiency of the modified lamellar nanofluid increased with the increase of oil sand particle size and temperature.What’s more,the oil-washing efficiency also increased rapidly at first,followed by a slow increase as the oil sand immersion time was extended,with an optimal immersion time of(8±2)hours.The oil-washing efficiency of the modified lamellar nanofluid could reach as high as 95.7%.These achievements break through the limitation that only high-concentration spherical nanoparticles can form structure disjoining pressure,providing a possibility for the applications of lamellar nanofluid in oilfield and a technical reference for pilot construction processes.