致密油岩心渗吸机理及表面活性剂提高采收率实验

Imbibition Mechanism of Tight Oil Cores and Experiments of Surfactants Enhancing Oil Recovery

目前随着三塘湖油田致密油注水吞吐轮次的增加,油水置换效率急剧降低。为研究合适的表面活性剂,提高致密油渗吸采收率,通过采用核磁共振技术,并发明定量测量黏附油的渗吸实验装置,研究致密油岩心渗吸机理及表面活性剂吐温20、吐温80和仲烷基磺酸钠+椰子油二乙醇酰胺(WLW)溶液对致密油渗吸采收率的影响。结果表明:过渡孔喉中的渗吸滞留和岩石表面黏附油产生的原因是随着渗吸的进行毛管动力减弱,无法克服流动阻力;分散乳化油滴、降低界面张力、改善润湿性、降低黏附功降低因子,可以降低流动阻力、提高渗吸动力或者提高渗吸的毛细管动力与阻力差值,提高油水置换效率,实现表面活性剂提高渗吸采收率的目的。研究结果为采用表面活性剂提高渗吸采收率的深入研究及致密油藏的高效开发提供了理论参考。

At present,with the increase of water injection multiple rounds of tight oil in Santanghu Oilfield,the efficiency of oil-water replacement has been dramatically reduced.In order to study suitable surfactants and improve the imbibition recovery of tight oil,nuclear magnetic resonance(NMR)technology and imbibition experimental device of quantitative measuring the viscous oil were used to investigate the mechanism of tight oil core imbibition and the effect of surfactants tween 20,tween 80 and sodium secondary alkyl sulfonate+coconutt diethanol amide(WLW)solution on recovery by tight oil imbibition.The results show that the reason for the retention of imbibition and oil adherence on rock surface in transition pore is that the capillary force weakens and the flow resistance cannot be overcome as the imbibition proceeds;Surfactants can disperse and emulsify oil droplets,reduce the interfacial tension between oil and water,improve the wettability of rocks,and reduce adhesion power reduction factors,thereby reduce the resistance of flow,improve the power of imbibition or improve the difference value between capillary power and resistance of imbibition,so improve oil-water displacement efficiency,and achieve the purpose of surfactant improving imbibition recovery.Through this research,the understanding of surfactant on improving imbibition recovery is deepened,which will provide experience for efficient development of tight reservoirs.