Comparison Between 180° and 360° Double Helix Capacitance Sensors for Measuring Water Holdup of Horizontal Oil–Water Stratified Flows

Flows of two immiscible liquids in horizontal pipes are often encountered in the petroleum industry. The complicated flow structures, which appear in horizontal oil–water two-phase flow, bring a great challenge to flow measurement. In this article, to investigate the feasibility of the double helix capacitance sensors for measuring the water holdup of the horizontal oil–water two-phase flow, the finite-element method (FEM) is applied to analyze the sensitivity distributions of the sensors with the helical angles of 180° and 360°. Then, a horizontal oil–water two-phase flow test system is built. An experimental study is performed to compare the water holdup measurement characteristics of the two different double helix capacitance sensors. Overall, the 180° double helix capacitance sensor is found to have better characteristics in the measurement of water holdup. The conclusion is supported by the sensor sensitivity compensation characteristics analysis with the FEM. Based on the measurement of water holdup, an experimental correlation is established between the water holdup and the water cut, and better results are obtained in the water cut prediction.