Selectivity of Pore-Scale Elastic Microspheres as a Novel Profile Control and Oil Displacement Agent

Pore-scale elastic microspheres were prepared controllably and their swelling property, stability, and creep-recovery property in brine water were analyzed in laboratory. The goal of the research was to study the selectivity of the pore-scale elastic microspheres as a novel profile control (water injection profile modification) and oil displacement agent. The matching factor between particle size of elastic microspheres and pore throat diameter of sand pack model was introduced to characterize their matching relationship. The results indicate that the optimal matching factor is 1.35–1.55. Besides, the profile control and oil displacement effect were studied using a series of heterogeneous double-tube sand pack models with optimal matching factors. The shunt flow experiments show that when the matching factor is an optimal value, the elastic microspheres prefer to plug the high-permeability layer selectivity and almost do not clog the low-permeability layer. The oil displacement experiments show that the elastic microspheres have the characteristic of plugging water without plugging oil and can improve the sweep status and oil displacement effect of low-permeability layer and low-permeability area in the high-permeability layer. According to the experimental results and actual situation of Block Liu 28-1, an optimal program for the profile control and oil displacement of elastic microspheres was proposed and conducted. The results show that the elastic microspheres can improve the water injection profile effectively. The results also confirm that the matching factor is an appropriate measure to evaluate the profile control and oil displacement effect of elastic microspheres and to guide the field test.