LAUSR

Water holdup measurement in multiphase flow with varying water salinity is a significant and challenging research topic. In this study, a new microstrip-antenna-based microwave transmission sensor (MAMTS) and a new decoupling method are proposed to achieve salinity independent measurement of water holdup in oil–gas–water slug flows. The MAMTS is formed by two identical microstrip antennas whose configurations are optimized and determined by the formula computation and the finite element method. Owing to the optimum design of the antenna configuration and the determination of the suitable working frequency, the amplitude attenuation and phase shift simultaneously measured by the MAMTS are both sensitive to the water holdup and water conductivity. To overcome the existing problem that the salinity affects the water holdup measurement only using amplitude attenuation or phase shift, a new decoupling method based on the simultaneous measurement of amplitude attenuation and phase shift is proposed. The measurement characteristics of the MAMTS to different flow structures with different water holdups and the influence of the water conductivity change are studied by the static experiments. Finally, the performance of the MAMTS and the decoupling method are evaluated in the experiment of oil–gas–water slug flows. The experiment results indicate that the amplitude attenuation and phase shift both can effectively sense the information of water holdup and water conductivity. However, they present different measurement characteristics to different flow structures. By taking the flow structures into consideration and using the new decoupling method, the water conductivity can be derived online and salinity independent water holdup measurement in oil–gas–water slug flow can be achieved.