A graphene oxide Janus nanosheets relative permeability modifier (RPM) for carbonate formations. The graphene oxide Janus nanosheets RPM may be used to treat a water and hydrocarbon producing carbonate formation to reduce water permeability in the formation and increase the production of hydrocarbons. The graphene oxide Janus nanosheet RPM includes a first side having negatively charged functional groups and a second side having alkyl groups. The alkyl groups may include C8 to C30 alkyls. The negatively charged functional groups may include carboxyl groups, epoxy groups, and hydroxyl groups. Methods of reducing water permeability of a carbonate formation using the graphene oxide Janus nanosheets RPM and methods of manufacturing the graphene oxide Janus nanosheets RPM are also provided.