Measurement of Water Holdup in Oil-Water Two-Phase Flows Using Coplanar Microstrip Transmission Lines Sensor

This paper presents the research of water holdup detection in oil-water two-phase flows and sensor design based on coplanar microstrip transmission line (also known as coplanar waveguide, CPW). The relationship between the CPW structure/material parameters and electromagnetic wave propagation characteristics was analyzed using conformal transformation method. Adopting double-sided and S-shaped wiring sheet structure, the dynamic range of detection is improved while the structure of the sensor is miniaturized. Therefore, multiple sensors can be arranged on the cross-section of the oil well to form a detection array, which can provide differential information of water holdup on the cross-section of horizontal wells or highly deviated wells and improve the spatial resolution of the measurement. Numerical simulations and experimental results show that the phase shifts of the signal detected by sensors are approximately linearly proportional to the water holdup of the measured fluid, the resolution is up to 3% in the whole range of water holdup from 0% to 100%. This method makes up for the disadvantages of capacitance method and conductance method, which are only effective for low water holdup and high holdup scenarios respectively.