Study on plugging performance of cross-linked polymer microspheres with reservoir pores

• Submillimeter-size microspheres were prepared by inverse emulsion polymerization.
• Cross-linked polyacrylamide microspheres have a good swelling property.
• Microspheres can be adsorbed, accumulated and bridged in pores.
• Microspheres can deform under pressure and can access deep into the reservoir.
• Microspheres show the best plugging performance when they match well with pores.

In this paper, scanning electron microscopy (SEM), microscopy and laser diffracting measurements experiments were adopted for investigating the shape and size of the linked polymer microspheres. Besides, nuclear-pore film filtration and sand packed tube displacement experiments were also adopted to investigate the matching relationship between the microspheres size and pores size. The results demonstrated that the original shape of the microspheres was typically spherical with a size range of 200 nanometers to 20 micrometers. When the microspheres were dispersed in water, their size increased due to swelling but spherical conformation remained. And the polydispersed microsphere system appeared. There was a certain matching relationship between the microsphere size and the membranes pores size, and the best plugging property could only occur when they were well-matched. A matching relationship also existed in the sand packed tube displacement experiment, and plugging could occur effectively only if sand packed tubes with low permeability were used.