Effect of modification degrees on the interfacial properties and EOR efficiency of amphiphilic Janus graphene oxide

Asymmetrically modified Janus graphene oxide (JGO) has attracted great attention due to its unique physical chemistry properties and wide applications. The modification degree of Janus nanosheets inevitably affects their interfacial activity, which is essential for their performances in enhanced oil recovery (EOR). In this study, the interfacial properties of Janus graphene oxide (JGO) with various modification degrees at liquid-liquid and liquid-solid interfaces were systematically evaluated via the measurements of interfacial tension (IFT), dilatational modulus, contact angle, and EOR efficiency was further assessed by core flooding tests. It is found that JGO-5 with higher modification degree exhibits the greater ability to reduce IFT (15.16 mN/m) and dilatational modulus (26 mN/m). Furthermore, JGO can construct interfacial and climbing film with the assistance of hydrodynamic power to effectively detach the oil from the rock surface and greatly enhance oil recovery. Moderately modified JGO-2 can highly improve recovery of residual crude oil (11.53%), which is regarded as the promising EOR agent in practical application. The present study firstly focuses on the effects of modification degrees on the JGO interfacial properties and proposes diverse EOR mechanisms for JGO with different modification degrees.