盐度响应型水包稠油乳状液的构建及其在多孔介质中的运移行为研究

Emulsions have attracted extensive attention in various fields of the oil industry due to their special properties. To solve the technical difficulties in the waterflood of heavy oil reservoirs including serious fingering and tongue phenomenon, severe water channeling and low oil recovery, salinity-responsive heavy oil-in-water emulsions developed by using the heavy oil in the oilfield, are proposed to be used as the in-depth conformance control agent and enhance heavy oil recovery. First, the influence of the preparation conditions of salinity-responsive heavy oil-in-water emulsions on their droplet sizes and the influence mechanisms of typical salt ions on their properties are investigated by using advanced analysis methods, in order to obtain the mechanisms of regulating the droplet sizes and the salinity range of emulsion phase inversion and its regulatory mechanisms. Also, coreflood tests and microscopic visual flood tests are conducted to study the migration, plugging mechanism and microscopic distribution of salinity-responsive heavy oil-in-water emulsions under different salinity gradients in porous media from both macroscopic and microscopic aspects. With the help of molecular simulation study, the influence mechanisms of typical salt ions on interfacial activity and the distribution characteristics of emulsifiers in salinity-responsive heavy oil-in-water emulsions are analyzed in order to reveal the main control factors and microscopic mechanisms of their phase inversion induced by typical salt ions. The project will provide scientific foundation and technical support for improving waterflood and enhancing heavy oil recovery.

乳状液由于其性能特殊受到石油工业各个领域的广泛关注。本项目针对稠油油藏注水开发面临的指进和舌进现象严重、注入水易沿高渗透通道突破、采收率低等复杂技术难题，利用油田现场稠油制备出高性能的盐度响应型水包稠油乳状液作为深部调剖剂来改善注水开发效果。首先借助先进分析测试手段，研究制备条件对盐度响应型水包稠油乳状液粒径的影响规律和典型盐离子对其性质的影响作用规律，明确粒径调控机制、乳状液发生转相的矿化度范围及其调控机制。同时，运用宏观岩心驱替和可视化微观驱替模拟相结合从宏观和微观两个角度，探明在不同盐度梯度下其在多孔介质中的运移规律、封堵机理和微观分布规律。再结合分子模拟研究，通过研究典型盐离子对盐度响应型水包稠油乳状液体系中乳化剂在界面膜上界面活性、分布特征的影响规律，揭示典型盐离子引发其转相的主控因素和微观机理。本项目为改善注水开发效果提高稠油油藏采收率提供科学依据和技术支撑。

本课题针对稠油油藏注水开发面临的指进和舌进现象严重、注入水易沿高渗透通道突破、采收率低等复杂技术难题，制备出高性能的盐度响应型水包稠油乳状液作为深部调剖剂来改善注水开发效果。通过借助先进测试手段和分子模拟方法，探讨了水包稠油乳状液的粒径调控机制、盐度响应性、在多孔介质中封堵机理以及典型盐离子引发其转相的微观机理。研究结果显示司盘80和蒙脱土纳米颗粒组成的最优乳化剂体系形成的水包稠油乳状液稳定性最好。典型盐离子（钠离子、钙离子和镁离子）均可引发该乳状液转相，引发转相能力顺序为Ca2+＞Mg2+＞Na+。超声波乳化机乳化功率和乳化时间可以控制乳状液的液滴大小。水包稠油乳状液在注入阶段具有较好的注入性和深部运移性，转相后水驱阶段中表现出良好的调剖性能，界面张力对其调剖性能具有重要影响。分子模拟研究显示盐浓度能够调控不同类型乳化剂在乳状液液滴界面膜上的竞争吸附行为，低盐度下蒙脱石纳米颗粒在界面膜上占据主导地位，高盐度下金属盐离子能使蒙脱石纳米颗粒聚集在水相中远离界面膜，从而使司盘80起到主导乳化作用，而且二价金属盐离子的调控作用比一价金属盐离子要强。本课题成功研发的盐度响应型 O/W 乳状液不仅能在石油领域发挥作用，也会在乳化食品、农药乳剂、纺织工业、建筑、医药等行业大放异彩，具有重大的经济效益和广阔的应用前景。