A multiphase flow metering device may have a conduit through which a multiphase fluid can flow and a structured packing insert positioned in the conduit. The structured packing insert may have a water-wet packing structure zone and/or an oil-wet packing structure zone. The multiphase flow metering device may also have a Halbach pre-polarizing magnet array positioned around the conduit, an RF coil, an electromagnet, an NMR console adapted to detect NMR signals from the multiphase fluid, and a control system configured to vary a polarization of the Halbach pre-polarizing magnet array. The Halbach pre-polarizing magnet array may be positioned or positionable over one or both of the oil-wet and water-wet packing structure zones. In some embodiments, the structured packing insert may include immobilized radicals, providing for dynamic nuclear polarization of the multiphase fluid.