乳状液对残余油的微流调节启动机制及触发条件

Microflow Adjustment Initiation Mechanism and Triggering Condition of Emulsion on Residual Oil

利用化学复合驱油体系对原油的乳化作用可启动微观残余油,从而提高驱油效率。为了确定乳化作用对残余油的启动机制以及实现这几种启动方式所需的条件,采用光学显微成像技术配合图像处理软件分析乳状液性质,以制备的乳状液作为驱替剂进行微观刻蚀模型驱油实验。结果表明,利用乳化作用启动残余油主要存在3种机制,即分散启动、携带启动和微流调节启动;微流调节启动机制通过乳状液颗粒堵塞作用和贾敏效应的叠加,可提高局部渗流阻力,改变微观液流方向,但对乳状液的颗粒数密度有一定要求;通过调整驱替剂的配方、注入时机和注入量可对乳状液的颗粒数密度进行调整,从而充分发挥乳状液提高驱油效率的作用。研究成果有助于化学复合驱理论的完善,并指导复合驱配方与注入方案的优化。

The emulsification of chemical combination flooding system on crude oil can initiate residual oil and then enhance the oil displacement efficiency. In order to determine the initiation mechanism of the demulsification on residual oil and the initiation conditions,the optical microscopy imaging and image processing software is used to analyze the emulsion properties. The laboratory microscopic flooding experiment with etch-model was carried out by using the prepared emulsion as a displacement fluid. Result indicates that there are three mechanisms for the initiating residual oil by emulsification,including dispersion initiation,carrying initiation and microflow adjustment initiation. The microflow initiation mechanism is superimposed by the plugging of emulsion particle and the Jiamin effect,which can increase local seepage resistance and change the microflow direction. However,there are certain requirements for the particle number density of emulsion in the microflow adjustment. The particle number density of the emulsion can be adjusted by changing the flooding fluid formulation,injection timing and the injection rate to fully improve the emulsion performance in enhancing oil displacement efficiency. This research could improve the chemical combination flooding theory and provide certain guidance for the combination flooding formulation and injection scheme optimization.