No abstract

Oil–water two-phase flows widely exist in industrial production, especially in the petroleum industry. The liquid holdup is significant for understanding reservoir production characteristics and improving oil recovery. This paper focuses on the helical capacitance sensor for the measurement of water holdup of oil–water two-phase flows. A new double helix capacitance sensor with an electrode rotation angle of 360° is designed. The sensitivity field distribution of the sensor with different parameters is simulated by the finite element analysis method, and the optimal geometric size of the sensor is obtained. The measurement characteristics of the sensor under different flow conditions are investigated by dynamical experiments of vertical oil–water flows. By analyzing the response signal of the helical capacitance sensor, the flow pattern can be identified, and the apparent water holdup can be calculated. The results show that the proposed sensor is suitable to measure the water holdup in a wide range of water cuts. Even in flow conditions of a high water cut, the sensor still retains good resolution in the D O/W flow pattern. This study expands the water holdup measurement of a capacitance sensor in the case of an oil–water two-phase flow with a high water cut.

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 finiteelement 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.