Measurement of water holdup in vertical upward high water-cut oil-in-water flows using a high frequency sensor

Abstract

In the present study, we propose a high frequency sensor (HFS) for water holdup measurement in high water-cut oil-in-water flow with low velocity. Through analyzing amplitude-frequency characteristics and phase-frequency characteristics of HFS in different working frequencies using the finite element method, the optimal working frequency of HFS is determined, and the relationship between the phase output of HFS and the water holdup is analyzed. With the designed HFS measurement system, an experiment of vertical upward high water-cut oil-in-water two-phase flow with low velocity is conducted in a 20 mm inner diameter (ID) pipe, through which the relationships among phase output signals of HFS, water-cut and total flow rate are obtained under the dispersed oil-in-water flow (D O/W). In addition, the variations of sensor output for changing water salinity are investigated. The results show that HFS possesses high water holdup measurement resolution which can substantially overcome the limitation that traditional conductance and capacitance method exhibit extremely low resolution in oil-in-water flows with both high water-cut and high water salinity. Based on drift-flux model, water-cut can be predicted with high accuracy.