Stabilization mechanism of viscoelastic polymer microspheres on N2 foam system

Abstract

Foam assisted flooding for crude oil displacement has been used as a commercially viable method for gas-enhanced oil recovery (EOR) processes, due to its outstanding ability in flow rate controlling. Micron-sized particles were continuously applied as the stabilizer for foam fluids, which can adsorb at the water–gas interface to increase interfacial elasticity, as such to prevent foam film rupture during bubble collisions. Current work synthesized two viscoelastic polymer microspheres by inversing emulsion polymerization, and evaluated their effectiveness as the foam fluids additives from the aspects of particle sizer and interfacial viscoelasticity. Furthermore, the ability of polymer microspheres to stabilize foam fluids was qualitatively analyzed according to the dynamics light scattering method and microscopic inspection. When containing 0.8 % SDS + 0.4 % polymer microspheres, the N2 foam system represented the most stable status for both viscoelastic polymer microspheres. The adsorption of microspheres at foam interface significantly increased the foam film strength that prevented lamella rupture when bubbles collision during the flooding process. Moreover, the sustained release property of viscoelastic polymer microspheres helped the fluid to be gradually released from the lamella, which further decreased the thinning speed of the liquid film between bubbles and to increase the foam stability.