▎ 摘　　要

In this article, we prepared Janus sulfonated graphene oxide nanosheets (JSGO) by a facile method for large-scale production. Unlike previous single-sided modifications of graphene oxide (GO), the smart JSGO nanofluid that can automatically find oil was obtained by modifying the double sides of GO. Benefiting from the introduction of sulfonic acid groups, JSGO had outstanding dispersity and stability under extreme conditions. Furthermore, JSGO exhibited excellent interfacial properties due to its amphiphilic characteristic. On the one hand, JSGO can reduce interfacial tension by 71% and form a strong interfacial film at the oil-water contact, achieving piston displacement with high sweep efficiency. On the other hand, JSGO had a strong ability in wettability reversal that can turn the hydrophobic surface into completely hydrophilic. These excellent properties of JSGO nanofluid contributed to obtaining an additional 18.4% recovery factor at low concentration (100 mg/L) and low injection volume (0.3 pore volume). As a result of the simple preparation, high performance, and excellent dispersion stability of JSGO nanofluid, it can be utilized as a chemical agent to enhance oil recovery in the harsh environment of reservoirs.