弱碱三元复合驱结垢机理探讨

Discussion on the scaling mechanism in weak base ASP flooding

为了认识在使用弱碱三元复合驱过程中油层伤害的问题,开展了室内岩心实验以了解弱碱三元复合驱储层结垢机理。通过室内岩心浸泡实验、串联岩心驱替模拟实验及岩心显微成像分析工作,初步确定了弱碱三元复合驱驱替过程中结垢离子,即阳离子主要为Ca2+,同时包括其他少量Mg2+、 Al3+等;串联岩心模拟水驱前岩心渗透率在123 mD上下浮动,后续串联岩心模拟水驱平均渗透率在8mD左右,渗透率值降低115mD,说明成垢阳离子与弱碱三元复合溶液中的CO32-结合成碳酸盐类难溶物或沉淀物,进而沉积成垢并堵塞地层。弱碱三元复合驱结垢机理的正确认识,为注入井解堵工作提供了技术支撑。

In order to understand the problem of oil reservoir damage in the process of using weak base ASP flooding,the indoor core experiment has been carried out to study the scaling mechanism of weak base ASP flooding in reservoir.Through the indoor core immersion experiment,it is preliminarily determined that the scale cations in the weak base ASP flooding are mainly Ca2+including a small amount of Mg2+、Al3+,etc.by the simulation test of serial core displacement as well as the micro-imaging analysis of core.The core permeability was about 123 mD before the serial core simulated water flooding,while the average core permeability was around became 8 mD after the serial core simulated water flooding,dropping 115 mD.It indicates that scale cations react with CO2-3 in the weak base ASP solution,and then form the carbonate type insoluble substance or precipitates so as to deposite and plug the formation.The correct understanding on the scaling mechanism in weak base ASP flooding can provide a technical support for removing plugs in the injection wells.