The preparation and displacement performances of a hollow structure microsphere with swelling–deswelling properties for enhanced oil recovery (EOR)

Polymer microsphere profile control is a promising approach for the profile control of heterogeneous reservoirs. Matching between polymer microspheres after swelling in water and the reservoir pore throat is crucial for profile control. Hydration equilibrium time and swelling ratio are key properties that are a direct result of water shutoff efficacy. In this paper, a hollow structure microsphere with swelling–deswelling properties is synthesized and its physical properties including morphology, particle size distribution, water swelling property and deswelling property are thoroughly examined. Meanwhile, the displacement performances are studied. The results demonstrate that the hollow structure microspheres have good swelling–deswelling properties at different salt concentrations. Compared with two kinds of polymer microspheres with the same material, the hydration equilibrium time of hollow structure microspheres is longer than that of nonhollow polymer microspheres. Moreover, the hollow structure microspheres have an effect on deep plugging. With the hydration time increasing, the tertiary recovery of the hollow structure microspheres solution is higher than that of nonhollow polymer microspheres solution, whether in a homogeneous medium or in a heterogeneous medium.