Imaging in electrically conductive porous media without frequency encoding

► We conceive an Earth-field NMR tomograph to image fluids on a 1 m3 sample scale. ► Low-frequency allows for operation in electrically conductive environments. ► Imaging is based on the coil sensitivity (no frequency encoding). ► We obtain a resolution of about 10 cm. ► Potential applications include monitoring CO2 injection into saline formations.