无碱二元复合体系驱油试验研究

针对大规模三元复合驱工业化应用中出现的一些问题,特别是注入的碱能引起地层黏土分散和运移,导致地层渗透率下降,碱也与油层流体及岩石矿物反应,形成碱垢,对地层造成伤害并影响油井正常生产;碱还会大幅度降低聚合物的黏弹性,从而降低波及体积等,研究合成了NEP无碱二元体系,对体系进行了评价,并进行了驱油试验研究与数值模拟,证明优化后的体系既克服了三元复合驱的缺点,又达到了其效果。在无碱二元体系中,表面活性剂的选择是关键技术,按界面张力达到10-2 mN/m数量级标准,最终选定了配制的活性剂NEP。系列驱油试验结果表明,所选体系也可以提高采收率约20个百分点。

Oil Displacement Test Research on Surfactant-Polymer System

ASP cooperates alkali, surfactant and polymer to flood oil reserves. It can produce a ultra low interfacial tension to oil with very low concentration of surfactant, and improve displacement efficiency largely; it enhance producible oil recovery factor largely. ASP experiment practice in Daqing Oilfield had gotten preferable effect, which enhanced producible oil recovery factor by 20%.But during the practical use of ASP ,some questions follow. Among them the most severe effect on oil and formation is that alkali can lower formation permeability because it can scrap formation clay and make them move and can form alkali scale, Alkali can lower largely viscoelasticity of polymer.As a result sweeping volume is lowered because of viscidity fingering. To surfactant-polymer system, in order to improve the oil recovery efficiently, a kind of better surfactant need be found. According to the request of interfacial tension attaining to 10 -2 mN/m in surfactant-polymer system, NEP system had been researched that has low interfacial tension and get rid of scale effect on viscoelasticity of flooding system. Its last producible oil index may equal that of APS. After experimental study, it has been concluded that new surfactant-polymer system can enhance producible oil recovery factor by 20%.