纳米级微球调剖剂的性能评价及自聚集封堵特性

低渗透油藏孔喉细小、结构复杂，常规体膨性微球调剖剂存在注入与封堵性矛盾，难以实现深部调剖。为解决这一矛盾，以苯乙烯、丙烯酰胺为单体，采用乳液聚合法制备了表面富含酰胺基团的聚合物微球调剖剂（CSA），向油藏中注入粒径小于孔喉直径的CSA微球分散溶液，运移到油藏深部后，在物理化学效应作用下微球自聚集成大尺寸的微粒簇，从而实现对流体通道的封堵。CSA微球具有低膨胀倍数，在向深部运移过程中能够有效避免剪切破碎；通过透射电镜可以观察到CSA微球在100 ℃老化35 d后，依然保持规则均匀的球形，热稳定性良好，并且微球具有核壳非均质结构。瓶试实验表明，随着阳离子浓度增加，CSA微球聚集时间逐渐缩短，并且二价阳离子的影响大于一价离子。岩芯驱替实验表明，CSA微球具有良好的注入性，聚集后的CSA微球团簇能够产生有效封堵并能运移至油藏深部起到调剖作用。

Performance Evaluation and Self-aggregation Plugging Characteristic of Nano Microspheres as Profile Control Agent

It is difficult to realize deep profile control because of the small pore-throats and complex structure of low-permeability reservoir,and there is contradiction between injection and plugging in traditional polymer microspheres.In order to solve this contradiction,a polymer micro sphere plugging agent(CSA)containing amide groups on the surface of micro spheres was prepared based on emulsion polymerization of styrene and acrylamide.The dispersed solution of CSA microspheres,whose particle size is much smaller than the diameter of pore-throats,was injected into the reservoir.When the microspheres migrated to the deep part of reservoir,these microspheres could automatically self-aggregate into large particle clusters because of the physical and chemical effects,so as to realize the plugging of the water channels.In this paper,the morphology,temperature resistance and self-aggregation properties of CSA microspheres were studied through transmission electron microscopy(TEM)and bottle test.The results showed that CSA microspheres exhibited heterogeneous core-shell structure,good dispersion,and outstanding thermal stability.The microspheres remain regular and uniform spheres at 100℃after aging for 35 days.With the increase of the concentration of the cations,the self-aggregation time of CSA was gradually shortened,and the influence of bivalent cations was greater than that of monovalent cations.Core flooding experiments showed that CSA microspheres have good injection properties,CSA microspheres clusters can effective plug the water channels and migrate to the deep part of the reservoir for profile control.