Sun Xianda, Wang Yuchen, Guo Qiansong, Ouyang Zhaozhuo, Xu Chengwu, Cao Yangdong, Liu Tao, Ma Wenjun
State Key Laboratory of Continental Shale Oil, Northeast Petroleum University, Daqing 163318, China.
Key Laboratory for Enhanced Oil & Gas Recovery of the Ministry of Education, Northeast Petroleum University, Daqing 163318, China.
Polymers (Basel). 2024 Dec 14;16(24):3494. doi: 10.3390/polym16243494.
In the process of oilfield development, the surfactant-polymer (SP) composite system has shown significant effects in enhancing oil recovery (EOR) due to its excellent interfacial activity and viscoelastic properties. However, with the continuous increase in the volume of composite flooding injection, a decline in injection-production capacity (I/P capacity) has been observed. Through the observation of frozen core slices, it was found that during the secondary composite flooding (SCF) process, a large amount of residual oil in the form of intergranular adsorption remained in the core pores. This phenomenon suggests that the displacement efficiency of the composite flooding may be affected. Research has shown that polymers undergo flocculation reactions with clay minerals (such as kaolinite, Kln) in the reservoir, leading to the formation of high-viscosity mixtures of migrating particles and crude oil (CO). These high-viscosity mixtures accumulate in local pores, making it difficult to further displace them, which causes oil trapping and negatively affects the overall displacement efficiency of secondary composite flooding (SCF). To explore this mechanism, this study used a microscopic visualization displacement model (MVDM) and microscopy techniques to observe the migration of particles during secondary composite flooding. By using kaolinite water suspension (Kln-WS) to simulate migrating particles in the reservoir, the displacement effects of the composite flooding system on the kaolinite water suspension, crude oil, and their mixtures were observed. Experimental results showed that the polymer, acting as a flocculant, promoted the flocculation of kaolinite during the displacement process, thereby increasing the viscosity of crude oil and affecting the displacement efficiency of secondary composite flooding.
在油田开发过程中，表面活性剂-聚合物（SP）复合体系因其优异的界面活性和粘弹性，在提高采收率（EOR）方面显示出显著效果。然而，随着复合驱注入量的不断增加，注采能力（I/P能力）出现了下降。通过对冻芯切片的观察发现，在二次复合驱（SCF）过程中，岩心孔隙中残留有大量以粒间吸附形式存在的残余油。这种现象表明复合驱的驱替效率可能受到影响。研究表明，聚合物在油藏中会与粘土矿物（如高岭土，Kln）发生絮凝反应，导致迁移颗粒与原油（CO）形成高粘度混合物。这些高粘度混合物在局部孔隙中聚集，难以进一步驱替，从而造成油藏滞留，对二次复合驱（SCF）的整体驱替效率产生负面影响。为了探究这一机理，本研究采用微观可视化驱替模型（MVDM）和显微镜技术观察二次复合驱过程中颗粒的运移。通过使用高岭土水悬浮液（Kln-WS）模拟油藏中的迁移颗粒，观察了复合驱体系对高岭土水悬浮液、原油及其混合物的驱替效果。实验结果表明，聚合物作为絮凝剂，在驱替过程中促进了高岭土的絮凝，从而增加了原油的粘度，影响了二次复合驱的驱替效率。
