During the process of chemical enhanced oil recovery (CEOR), surfactants are widely used as they can reduce interfacial tension and change surface wettability, but the huge economic losses caused by the adsorption of surfactants on rock surface need to be resolved. Therefore, polyelectrolyte is introduced to reduce the adsorption amount of surfactant. However, how to select appropriate polyelectrolyte suitable for different reservoirs is always lack of theoretical guidance. Herein, the competitive adsorption mechanism between surfactant and polyelectrolyte on rock surface is studied by classical density functional theory (CDFT). Having investigated the effects of different polyelectrolytes on the adsorption of surfactants, the optimal polyelectrolyte concentration and chain length suitable for different potentials were found. Also, the influence of rock crevices width on displacement effect was considered. Moreover, we proposed a comprehensive evaluation of polyelectrolytes in terms of both the performance and economy. The findings of this study benefit for further understanding of the competitive adsorption in CEOR, and provide guidance for the practical application of polyelectrolytes.

在化学强化采油（CEOR）过程中，表面活性剂因其降低界面张力、改变表面润湿性而被广泛使用，但表面活性剂吸附在岩石表面造成的巨大经济损失亟待解决。因此，引入聚电解质以降低表面活性剂的吸附量。然而，如何选择适合不同储层的聚电解质一直缺乏理论指导。本文采用经典密度泛函理论（CDFT）研究表面活性剂与聚电解质在岩石表面的竞争吸附机理。研究了不同聚电解质对表面活性剂吸附的影响，找到了适用于不同电位的最佳聚电解质浓度和链长。还，考虑了岩缝宽度对位移效应的影响。此外，我们提出了对聚电解质在性能和经济性方面的综合评价。本研究结果有助于进一步了解CEOR中的竞争吸附，为聚电解质的实际应用提供指导。