Electrically conductive oil-based wellbore fluids and methods of using same are provided. Wellbore fluids provided may contain one or more carbon nanotubes, where the one or more carbon nanotubes have a particular d/g ratio as determined by Raman spectroscopy. Also provided are methods for electrical logging of a subterranean well that include emplacing a logging medium into a subterranean well, wherein the logging medium contains a non-aqueous fluid and one or more carbon nanotubes, where the one or more carbon nanotubes are present in a concentration so as to permit the electrical logging of the subterranean well; and acquiring an electrical log the subterranean well.