超临界CO2微乳液体系的构筑及其驱油机理研究

Supercritical carbon dioxide microemulsions have been widely used in extraction, chemical reaction, synthesis of material, cleaning and other fields with excellent performance. Although CO2 flooding has a good prospect used in enhancing oil recovery (EOR), especially in tight and heavy oil reservoirs, the difficulty of controlling its mobility limits the application of CO2. With the help of surfactant the formed CO2 foam or microemulsion can be used to control the mobility effectively. In this project we will investigate the formation of supercritical CO2 microemulsion by using commercial surfactants readily available for oilfield applications and the oil displacement efficiency under the tight and heavy oil reservoir conditions. We will carry out experiments to study the physicochemical properties of the supercritical CO2 microemulsion-crude oil-rock system (such as interfacial tension, wettability, viscosity and viscoelasticity, etc.) and the flow characteristics in porous media. We will derive the relationship between physicochemical properties and flow characteristics of supercritical CO2 microemulsion in porous media. We will also investigate the effects of physicochemical properties and flow characteristics on the oil displacement efficiency in order to find out the displacement mechanisms of supercritical CO2 microemulsion injection.

超临界CO2微乳液体系已经广泛地应用在萃取、有机合成、纳米材料制备及清洗等领域，并且表现出优异的性能。在三次采油特别是对低渗透、稠油类油藏的开采方面，CO2驱油技术具有良好的应用前景，但是CO2流度难控制的特点限制了其在油田开采中的应用。利用表面活性剂和CO2形成泡沫或微乳液作为驱油体系则可以起到控制CO2流度的效果。因此，本项目拟利用油田常用的表面活性剂来构筑超临界CO2微乳液体系，研究超临界CO2微乳液体系在低渗透、稠油油藏条件下的驱油效率。并进一步考察超临界CO2微乳液体系与原油间的界面张力、体系对岩石表面润湿性的影响及体系的粘度和粘弹性等物化性能及微乳液体系在多孔体中的流动特性等。通过实验研究，弄清超临界CO2微乳液体系的流动特性与物化性能之间的关系，得到超临界CO2微乳液体系的驱油效率与流动特性及物化性能之间的内在关系，揭示超临界CO2微乳液体系的驱油机理。

超临界CO2 微乳液体系已经广泛地应用在萃取、有机合成、纳米材料制备及清洗等领域，并且表现出优异的性能。在三次采油方面，CO2 驱油技术可以对低渗透、稠油类油藏进行有效地开发，但是CO2 流度难控制的特点限制了其在油田开采中的应用。利用表面活性剂和CO2 形成泡沫或微乳液作为驱油体系则可以起到控制CO2 流度的效果。本项目利用几种新合成的表面活性剂成功的构筑超临界CO2 微乳液体系，研究超临界CO2 微乳液体系针对低渗油藏的驱油效率，考察了超临界CO2体系对页岩油采收率的提高程度。并且进一步考察超临界CO2 微乳液体系与原油间的界面张力及复合体系的粘度和粘弹性等物化性能，考察了聚合物存在时对超临界CO2体系粘度的影响规律。通过实验研究，分析了超临界CO2 微乳液体系的驱油效率与流动特性及物化性能之间的内在关系，揭示了超临界CO2 微乳液体系的驱油机理。