Development and evaluation of a Janus amphiphilic carbon nanotube-based nanofluid for enhanced heavy oil recovery

Heavy oil stands as a pivotal unconventional resource. The reduction of heavy oil viscosity through emulsification emerges as a critical strategy for augmenting its recovery. In this study, a novel Janus amphiphilic carbon nanotube (JCMS18) was synthesized utilizing Pickering emulsion templating and emulsion polymerization. The structural integrity of JCMS18 was meticulously characterized employing Fourier-transform infrared spectroscopy, atomic force microscopy, scanning electron microscopy, and transmission electron microscopy. Contact angle measurements further confirm the unique amphiphilicity of JCMS18. A JCMS18-based nanofluid viscosity reducer was subsequently formulated by amalgamating JCMS18 with cocamidopropyl betaine and sodium alcohol ether sulfate. The findings revealed that JCMS18 exhibits exceptional interfacial tension (IFT) reduction capabilities. At a concentration of 0.02 wt. %, JCMS18 diminished the oil–water IFT to 15.8 mN/m. The JCMS18 nanofluid further reduced the heavy oil/water IFT to 5.418 × 10−2 mN/m. Microscopic displacement experiments disclosed that the JCMS18 nanofluid significantly curtailed residual oil saturation, encompassing blind-end, columnar, cluster, and film-like residual oil. Core flooding experiments demonstrated that 0.3 pore volumes of JCMS18 nanofluid enhanced oil recovery by 26.16% in a 1500-mD core. Nuclear magnetic resonance displacement experiments corroborated that the primary mechanisms of JCMS18 for enhanced oil recovery are emulsification, viscosity reduction, and wettability alteration. These findings underscore the substantial potential of JCMS18 nanofluid for heavy oil development.