Preparation and salt-insensitive behavior study of swellable, Cr3+-embedded microgels for water management

The microgels have been used in the oilfield for water management and enhanced oil recovery (EOR). Fully swollen size of the microgels is very sensitive to salt, which brings uncertainties on the performance of microgel treatments. Herein, a Cr3+-embedded polyacrylamide based microgel, synthesized via a free-radical suspension polymerization, is described which could significantly weaken the salt-sensitivity of the microgels. Embedment of Cr(3+)in the polymeric networks of microgels crosslinked through covalent bonds has been studied using the scanning electron microscopy (SEM), FT-IR, and dialysis analysis. The effects of crosslinker concentration, initiator concentration, and the stirring rate during polymerization on the size of the microgels have been characterized. In addition, contrary to the commercial microgels, the fully swollen size of the Cr3+-embedded microgels performed insensitivity to the salts, such as sodium chloride (NaCl), calcium chloride (CaCl2), and aluminum chloride (AlCl3). Moreover, the pore occlusion experiments demonstrated the Cr3+-embedded microgels also have the same viscoelasticity at different salt concentrations, resulting in the similar plugging performance. The Cr3+-embedded microgel shows a great potential for improving the microgel plugging for water management and enhanced oil recovery. Published by Elsevier B.V.