界面性质对表面活性剂洗油效率影响研究

Effect of Interfacial Characteristics on Oil Removal Efficiency of Different Surfactants

表面活性剂通过改变油-水-岩石界面性质,可以提高稠油流动能力,促进采收率的提高。然而,界面相互作用力的改变对洗油效率和采收率的影响难以精确量化。提出了一种激光共聚焦成像及图像处理的方法分析洗油前后原油的分布,并计算洗油效率。实验及计算结果显示,界面张力对洗油效率的影响较小,而系统润湿性和黏附功的影响更为显著。黏附功结合了表活剂对界面张力和润湿性的影响,是表活剂评价和筛选的一个重要参数。另外,固体表面的润湿反转使得表活剂的洗油效率随时间发生了改变。将洗油实验和激光共聚焦成像及图像处理相结合,精确计算了洗油效率,揭示了界面性质对洗油效率的影响,对化学驱提高稠油采收率具有重要指导意义。

Surfactants are widely used to reduce oil-water interfacial tension,alter wettability of rock surface,and thus reduce the adhesion between residual oil and rock surfaces,which can improve mobility of heavy oil and enhance recovery rate.However,the effect of the change of interfacial forces on oil removal/recovery rate can hardly be quantified accurately.Here,based on laser scanning confocal microscopy,an image analysis method was proposed for the measurement and calculation of oil removal rate for different surfactant-oil-rock systems.In the oil-removal experiments,micro-structured glass surfaces were first saturated with oil.Then sonicator was used to assist the oil removal from the saturated surfaces by different surfactants.The results showed that the increase of oil removal rate was mainly caused by reduction of work-of-adhesion and wettability alteration rather than change of interfacial tension.In fact,work-of-adhesion is a combination of interfacial tension and wettability,which makes it a preferable parameter for evaluation of surfactants.Meanwhile,the oil removal efficiency of surfactants with different concentration changes with time,which is also caused by wettability alteration.By integrating oil removal experiments with laser scanning confocal microscopy and image analysis,accurate calculation for oil removal efficiency was carried out to reveal the effects of interfacial characteristics on oil removal efficiency.This paper provides insights into heavy oil EOR by chemical flooding.