Oil-gas-water three-phase flow metering device and metering method

The invention discloses an oil-gas-water three-phase flow metering device which comprises a cyclone separator and a flow computer, a liquid level meter is arranged at the top of the cyclone separator, a differential pressure transmitter is arranged on the side face of the cyclone separator, a fluid inlet pipe is arranged on the side face of the cyclone separator, a liquid phase pipeline is arranged at the bottom of the cyclone separator, and the flow computer is connected with the liquid phase pipeline. The liquid-phase pipeline is communicated with a fluid inlet pipe through a connecting pipeline, a gas-phase pipeline is arranged on the side face of the cyclone separator, the ends, away from the cyclone separator, of the liquid-phase pipeline and the gas-phase pipeline are communicated with each other, a fluid outlet pipe is arranged at the communication position of the liquid-phase pipeline and the gas-phase pipeline, and a gas-liquid two-phase flowmeter is arranged on the liquid-phase pipeline. And a gas f