表面活性聚合物驱油剂的合成及性能研究

Study of preparation and properties of surface-active polymers for oil displacement agent

关键词:  表面活性聚合物  复合驱  界面张力  色谱分离  采收率

Key words:  surface-active polymer  compound flooding  interfacial tension  chromatographic separation  recovery rate

摘要:

针对聚合物/表面活性剂复合驱中聚合物与表面活性剂黏度差异导致其在地层中运移不同步而发生的色谱分离,以及常规驱油用聚合物无表面活性的问题,利用可聚合表面活性单体(YCM)、丙烯酰胺(AM),借助于复合引发体系,控制低温聚合的方法,合成了具有增黏性与界面活性的驱油用表面活性聚合物。红外光谱表征表明表面活性聚合物分子结构中含有磺酸基团(SO₃-)、苯环、长链亚甲基疏水基团,目标产物与分子结构设计吻合。优化出表面活性单体YCM质量分数为1.5%～2.5%,引发剂质量分数为0.04%～0.06%。表面活性聚合物在大庆模拟盐水中具有较好的溶解性(溶解时间为85 min)、增黏性(表观黏度>40 mPa·s,7.34 s-1)及降低油水界面张力的能力(10-2 mN/m数量级)。岩心驱替实验结果表明,表面活性聚合物比常规聚合物/石油磺酸盐提高采收率2.5%,表面活性聚合物起到了聚合物与表面活性剂二元复合驱的作用,抑制了二元复合驱的色谱分离,实现了表面活性聚合物既能扩大波及体积又能提高洗油效率的功能,对高含水油田提高采收率具有重要意义。 

Abstract:

In polymer/surfactant di-composite flooding, the viscosity difference between polymer and surfactant results in chromatographic separation due to asynchronous migration in formation, and the conventional polymer for oil displacement has no surface activity. Based on above problems, a surface-active polymer with viscosity increasing ability and interfacial activity as oil displacement agent was prepared by using composite initiation system and the method of low-temperature polymerization with the polymerizable surface-active monomer(YCM) and acrylamide(AM). The infrared characterization showed that the surface-active polymer contained sulfonic acid group (SO-₃), benzene ring and long-chain methylene hydrophobic group, and the target product was consistent with the molecular structure design. The optimum polymerization conditions showed that the mass fraction of YCM was 1.5%-2.5%, and the concentration of initiator was 0.04%-0.06%. The surface-active polymers had good solubility(dissolving time of 85 min), viscosifying properties(apparent viscosity above 40 mPa·s,7.34 s-1) and the ability to reduce oil/water interfacial tension(the order of 10-2 mN/m) in Daqing simulated brine. The displacement experiment showed that the enhanced recovery of surface-active polymer was 2.5% higher than that of conventional polymer. The main reason is that surface-active polymer plays a role in the dual interaction of polymer flooding and surfactant flooding, and also suppresses the chromatographic separation of the polymer/surfactant di-composite flooding. It can not only expand swept volume, but also improve oil washing efficiency in the whole displacement process. Therefore, the surface-active polymer has great significance to improve the recovery rate of high water-cut oil fields.