The preparation and spontaneous imbibition of carbon-based nanofluid for enhanced oil recovery in tight reservoirs

In this work, carbon-based nanofluid was prepared composed of hydrophilic carbon nanoparticles (CNPs) and Tween-80 to enhance oil recovery through spontaneous imbibition in tight reservoirs. The CNPs were characterized by transmission electron microscopy (TEM), dynamic light scattering (DLS), 1HNMR, interfacial tension and wettability measurements. The particle size of CNPs was <10 nm and CNPs nanofluid showed excellent stability at high temperature and high salinity. CNPs nanofluid exhibited a stronger ability to reduce interfacial tension and change wettability than brine. The 1HNMR imaging showed that CNPs had seeped into the core. The spontaneous imbibition tests showed that the spontaneous imbibition oil recovery of CNPs nanofluid can reach 24%, compared with 11% oil recovery of NaCl solution. CNPs nanofluid can efficiently enhance oil recovery, which was ralated to capillary force and structural disjoining pressure. CNPs nanofluid has great potential for enhancing oil recovery, especially in tight reservoirs.