Aqueous suspensions of carbon black with ethylenediamine and polyacrylamide-modified surfaces: Applications for chemically enhanced oil recovery

Enhanced oil recovery (EOR) technologies mitigate the demand for new reservoirs and are pathways for more efficient uses of non-renewable hydrocarbons. Hydrolyzed polyacrylamide (HPAM) has been used as a thickening agent in aqueous media for EOR. However, HPAM shows low salt and temperature tolerances. Carbon black (CB) is a nanoparticle that exhibits chemical and thermal stability but poor dispersability in polar solvents. In this work, CB surfaces were sequentially modified with ethylenediamine (EDA) and acrylamide (AM) to fabricate CB-EDA-AM particles. These particles had increased nitrogen levels from 0.33% at the CB to 7.19% in the CB-EDA-AM, and the formation of amine and amide groups were identified by XPS analyses. TEM and AFM images suggest the formation of oligomers on the CB-EDA-AM surfaces, which was confirmed by the presence of a glass transition temperature at 114 °C in the DSC curve. For the first time, we report that in harsh salinity and elevated temperature conditions, 5 ppm of surface-modified CB nanoparticles can enhance the rheological stability of HPAM aqueous fluids. A shear stress test performed in brine medium indicated the modified CB particles have showed a maximum gain of 29% in stability at high shear rates compared with neat polymeric solutions.