Multi-phase fluid measurement using low activity sources

A fluid measurement device, comprising:

• a fluid container comprising an inlet side and an outlet side opposite the inlet side, the fluid container configured to direct a fluid in a non-horizontal direction from the inlet side to the outlet side, the fluid container defining an interior and having a diameter line perpendicular to the non-horizontal direction;
• an exempt gamma-ray source located external to an outer wall of the fluid container to emit photons into the interior of the fluid container;
• and
• a gamma-ray detector located external to the outer wall of the fluid container, the exempt gamma-ray source and the gamma-ray detector defining a photon path having a photon path length of from 3 cm to 6 cm, wherein at least a portion of the photon path traverses the interior of the fluid container in a direction parallel to, and spaced apart from, the diameter line, and the photon path is along a non-diametric chord of the fluid container.

A method of fluid flow measurement, comprising:

• disposing an exempt gamma-ray source and a gamma-ray detector outside a fluid container to define a first photon path between the exempt gamma-ray source and the gamma-ray detector that traverses an interior of the fluid container along a non-diametric path;
• disposing a microwave transmitting antenna and a microwave receiving antenna outside the fluid container to define a second photon path between the microwave transmitting antenna and the microwave receiving antenna that traverses the interior of the fluid container;
• flowing a non-separated multi-phase fluid through the fluid container in a vertical direction from an inlet side to an outlet side of the fluid container, the fluid container having a diameter line perpendicular to the vertical direction;
• while flowing the non-separated multi-phase fluid through the fluid container, obtaining a count rate of gamma photons propagated through the non-separated multi-phase fluid using the exempt gamma-ray source and the gamma-ray detector and measuring dielectric properties of the non-separated multi-phase fluid using the microwave transmitting antenna and the microwave receiving antenna;
• measuring pressure drop as the non-separated multi-phase fluid flows through a flow restriction of the fluid container;
• determining water-liquid ratio of the non-separated multi-phase fluid from the count rate of gamma photons;
• determining a gas fraction of the non-separated multi-phase fluid from the dielectric properties and the water-liquid ratio;
• calculating a mixture density of the non-separated multi-phase fluid based on the water-liquid ratio and the gas fraction;
• determining volumetric flow rate of the non-separated multi-phase fluid from the measured pressure drop and the mixture density;
• and
• determining volumetric flow rates of gas, water, and oil in the non-separated multi-phase fluid from the volumetric flow rate of the non-separated multi-phase fluid, the gas fraction, and the water-liquid ratio.