Multiphase flowmeter for oil, water and gas in pipelines based on gamma-ray transmission techniques

A multiphase flowmeter (MFM) has been developed to determine the mass flow rates of oil, water and gas in pipelines. It is based on two specialized γ-ray transmission gauges mounted on a pipe carrying the full flow of oil, water and gas. One gauge uses single energy γ-ray transmission and the other dual energy γ-ray transmission (DUET). Pressure and temperature are also measured. Calculations show that the DUET gauge determines the mass fraction of oil in the liquids, and the volume fractions of oil, water and gas, with an accuracy sufficient for most multiphase flow applications. The velocity of flow is determined by cross-correlation of the outputs of the two gauges, one mounted downstream of the other. The two gauges were tested on flows in a water/air loop; the flow rates of water and air were determined to better than 5% relative. (author)