Migration characteristics and plugging rules of self-aggregating nanoparticles in the porous media

Nanoparticle profile control agents have been widely used for water shut-off treatment due to their excellent properties. However, the contradiction between the injectability and the plugging characteristics of profile control agents seriously affects their sealing effect. Self-aggregating nanoparticles can effectively alleviate this contradiction by forming particle clusters in the formation to block water channels. In this study, the injection and plugging properties of self-aggregating nanoparticle profile control agents in porous media were investigated using visual porous media etching model and core model. Injectivity experiments showed that the flow of nanoparticles in porous media was divided into three phases: flow dispersion phase, self-aggregation migration phase, and aggregation plugging state. They could aggregate to form clusters similar to the pore throat size after 60 min. Core displacement experiments showed that the plugging performance of nanoparticles was influenced by solution concentration, injection volume, injection rate, and core permeability. When injecting a 3000 mg/L nanoparticle solution into the core at 60 °C, the residual resistance coefficient was larger than 1.83. The retention rate in pore throats was superior to 60%.