Measurement of High Water Holdup in Oil-in-Water Flows Using Reticular Microwave Resonant Sensor

Long-term waterflooding exploitation leads to the low flow rate and high water cut of the oil-water flows in oil wells, which has put forward a new challenge for the water holdup measurement. Therefore, a reticular microwave resonant sensor (RMRS) is proposed in this article, which can realize the high-sensitive water holdup measurement of oil-in-water flows with high water cut and low velocity at 1.85-2.3 GHz. Due to the optimum design in the quasi-TEM mode of the sensor based on the finite-element method, the resonant frequency shift measured by the RMRS is sufficiently sensitive to the water holdup. After the viability of the sensor is confirmed through a simulation experiment, a sensor prototype is prepared. And the measurement characteristics of the sensor to the water holdup are first investigated by the static experiment. Subsequently, the dynamic experiment of vertical upward oil-in-water flows is carried out. The response characteristics of the RMRS with the change of water salinity, flow rate, and water cut are analyzed. Finally, a satisfactory relationship between the resonant frequency and water holdup with the consideration of water salinity is obtained. It shows that the RMRS has a good resolution to the water holdup. Moreover, it can effectively restrain the influence of water salinity.