Flowrate measurement of vertical oil-gas-water slug flow based on basic temperature and differential pressure signals

A novel online, non-separation, nearly non-intrusive, non-radiation method based on basic temperature and differential pressure signals is proposed to measure the oil–gas–water three-phase flow in this paper. The temperature fluctuations in the heated pipe wall caused by Taylor bubbles and liquid slugs were analyzed and used to capture their velocity and length, and the fluid flow and differential pressure in the branch pipe were investigated to acquire the oil holdup in liquid phase. Then, a theoretical model was built to correlate the obtained flow characteristics with flowrates of individual phase. Experimental results indicate that the empirical correlations for temperature fluctuations in developed gas–water slug flow are still applicable to the oil–gas–water slug flow, and the proposed method and theoretical model are effective and accurate with root-mean-square errors of 0.01, 0.03, and 0.04 m3/h for the calculated flowrate of oil, gas, and water, respectively.