Abstract:

The process and mechanism of emulsion flooding is the basis for the development of emulsion flooding technology. A microfluidic visualization system was established to explore the two-phase flow characteristics of emulsion flooding and its influencing factors in porous media. The results show that the displacement mode of water and surfactant is viscous fingering, and the emulsion flooding is accompanied by droplets plugging, which can effectively inhibit viscous fingering, enhance interfacial stability and improve the displacement efficiency. The influences of capillary number, viscosity ratio and droplet to pore size ratio on the emulsion flooding were explored, and by establishing the distribution phase diagram of emulsion displacement mode with different viscosity ratio and capillary number, the transformation boundaries of stable displacement and viscous fingering of nanoparticle surfactants displacement in porous media is obtained. It is proved that emulsion can substantially increase the critical capillary number and viscosity ratio required for viscous fingering to occur, and effectively improve the spread efficiency and displacement efficiency, which provides a theoretical basis for the use of emulsion in actual crude oil extraction.

Key words: porous media, two-phase flow, microchannels, emulsion flooding, enhanced oil recovery

摘要：

了解乳状液在多孔介质中的驱油过程及其机理，是发展乳状液驱油技术应用的基础。搭建了微流体可视化实验平台，揭示了多孔介质中乳状液驱油过程的两相流动过程及其影响因素。结果表明，水和表面活性剂的驱替模式均为黏性指进，使用乳状液驱油会产生液滴堵塞效应，能有效抑制黏性指进，增强界面稳定性，提高驱替效率。分析了毛细管数、油相-驱替相黏度比和液滴-孔隙尺寸比对乳状液驱油的影响，并通过建立基于不同毛细管数与黏度比下的驱替模式分布相图，得到了多孔介质中乳状液稳定驱替和黏性指进两种驱替模式的转变界限，证明乳状液驱对比水驱提高了黏性指进出现的临界毛细管数和黏度比，有效提高了驱替稳定性和驱替效率，为利用乳状液进行实际原油开采提供了理论基础。

关键词: 多孔介质, 两相流, 微通道, 乳状液驱, 提高采收率