Welan gum has been widely used in harsh reservoir development, such as good thickening ability, temperature and salt resistance. However, viscoelasticity is crucial to polymer injectability and microscopic displacement efficiency, Welan gum have rigid helical conformation and show poor rheological properties., therefore, we proposed a double network strategy to improve the molecular conformation and rheological properties of Welan gum. Specifically, we synthesized β-cyclodextrin functionalized polyacrylamide (HPAM-CD) and adamantane modified Weland gum (WL-AD), and polyacrylamide and Welan gum through the supramolecular interaction to obtain double network crosslinking system (WL-AD&HPAM-CD). Rheology show that the double-network system driven by multiple non-covalent interaction has excellent rheological properties. Circular dichroism, atomic force microscopy and scanning electron microscope show that WL-AD&HPAM-CD forms a special molecular conformation, significantly improve the molecule elasticity of biopolymers, it has good conformational stability under harsh conditions. Therefore, oil recovery rate of WL-AD&HPAM-CD after water flooding in 200 mD cores is 4.99 % and 11.5 % higher than that of the same concentration of Welan gum and grafted Welan gum. In addition, WL-AD&HPAM-CD has excellent fluidity in 10-50 mD low permeability reservoirs, and can increase oil recovery by 12.17–17.16 % after water flooding. This study provides a research ideas for the development and application of biopolymers.
Nanoparticles and surfactant enhanced foams exhibit exceptional potential for the creation of environmental-friendly firefighting foams. In this work, we employ an ultrasonic disperser to fabricate a foam dispersion comprising Gemini surfactants, zwitterionic LAMC surfactants, nanosilica particles (NPs), and water-soluble polymer Welan. The enhancement mechanism of foam performance by NPs and Welan was investigated. The results show that the addition of 3% NPs and 0.07% Welan reduced surface tension by 14.56%, increased conductivity by 19.60%, and raised solution viscosity by 568.46%. Dynamic Light Scattering (DLS) and Cryogenic Transmission Electron Microscopy (Cryo-TEM) revealed that the inclusion of Welan transformed the micelles in the Gemini/LAMC solution from spherical to coacervates structures. The increase in viscosity was attributed to the formation of irregular coacervates when Welan and NPs were combined. Ross-Miles tests showed that the addition of NPs could increase foam volume by up to 12.91%, while the inclusion of Welan consistently reduced foam volume. Foam drainage and coarsening results demonstrated that the entanglement effect of Welan and the concentration blocking effect of NPs jointly enhanced foam stability. Incorporating 3% NPs creates an interconnected network that strengthens the foam structure and improves its stability. of 0.07% Welan gum. Within the experimental range, controlling the concentration ratio of NPs and Welan allowed for the simultaneous enhancement of foaming ability and stability of the firefighting foam. This study can provide theoretical guidance for application of NPs in firefighting foams.
危险品化学品经营许可证（带存储）