Multi-supramolecular and double-network strategy improves rheological properties and oil displacement efficiency of polymers

Abstract

In enhanced oil recovery (EOR), the application of polymer systems in harsh reservoir conditions is limited. This study conducted a proof-of-concept study of multi-supramolecular interactions and dual-network strategies, motivated by the desire to gain insights into the effectiveness of these higher-order self-assembled polymer flooding. Xanthan gum dual network supramolecular polymer (DN-HXG) system was obtained by multi-supramolecular cross-linking of polyacrylamide and xanthan gum, and compared with hydrophobic polyacrylamide/hydrophobic xanthan gum (HMPAM/MXG) mixture and polyacrylamide/xthan gum (HPAM/XG) mixture. The thickening and temperature and salt tolerance mechanisms of DN-HXG were analyzed by environmental scanning electron microscopy (ESEM), dynamic light scattering (DLS) and fluorescence spectra. The results show that the DN-HXG system has excellent viscoelastic and shear resistance. Due to the presence of multiple supramolecular interactions and rigid xanthan gum molecular chains, DN-HXG can withstand environments of more than 120 ℃ and 50 g/L salinity, which has good applicability in harsh reservoirs. In laboratory oil displacement experiments, DN-HXG shows obvious advantages in low-permeability core, and the recovery rate of DN-HXG is more than 20 % higher than that of conventional polymer. These experiments show that the strategies described can be applied to other synthetic polymers and biopolymers to improve their oil displacement properties.