Performance Evaluation of Peanut‐Shaped Polystyrene Nanospheres as Profile‐Control Agents

ABSTRACT

Polymer microspheres are profile‐control agents for plugging high‐permeability reservoir zones, regulating injection profiles, and enhancing oil recovery (EOR) owing to their small size and strong retention. However, most studies focus on spherical microspheres, whereas peanut‐shaped anisotropic particles remain rarely investigated. Herein, peanut‐shaped polystyrene (P‐PS) particles prepared through an optimized emulsion‐polymerization route reported in our previous work were evaluated as anisotropic profile‐control agents for EOR and compared with spherical PS particles (S1‐PS and S2‐PS). Core plugging tests showed that P‐PS particles, with an apparent hydrodynamic diameter of 72 nm and an aspect ratio of 2.44, achieved a plugging efficiency of 85.72% in a 200 mD core, representing increases of 61.56% and 28.69% over S1‐PS (160 nm) and S2‐PS (65 nm), respectively. SEM confirmed that P‐PS particles migrated into the porous medium and were retained within pore spaces. Under 70°C, 200 mD, 1.8 PV, and 1000 mg/L, P‐PS produced an incremental EOR of 12.97%, 4.40, and 1.37 percentage points higher than those of S1‐PS and S2‐PS, respectively. At 5000 mg/L, EOR reached 18.70%, although injection pressure approached the limit. This study provides insight into anisotropic particle transport and retention in porous media and supports their profile‐control potential.