Polymer-Stabilized Multi-Walled Carbon Nanotube Dispersions in High-Salinity Brines

Carbon nanotubes (CNTs) exhibit promising properties for potential applications in oil and gas reservoirs. CNTs can be used as delivery vehicles for contrast agents or catalyst nanoparticles deep inside the reservoir. Dispersing 100 ppm of CNTs in deionized water is easily achieved by sonication of CNTs using properly selected surfactant or polymer solutions. These surfactants and polymers are non-covalently adsorbed to the nanotube surface, inducing dispersion stability. In oil reservoirs, high salinity is the norm; therefore, because the electrostatic double layer is compressed as a result of the high ionic strength found in a typical reservoir brine, colloid CNT dispersions lose stability and CNTs flocculate and precipitate. To maintain a stable colloidal dispersion of CNTs, a dispersant with functionality providing steric repulsion between the dispersed tubes is needed to prevent aggregation. In this work, suspensions of multi-walled carbon nanotubes (MWNTs) were generated using two polymers, gum arab...