Dual-modality microwave-conductivity sensing system for flow characterization in high water-cut production wells

This study introduces a novel microwave-conductivity dual-modality sensing system for liquid-liquid flow measurement in oilfield water injection. The system combines a flexible microstrip array antenna (FMAA) for water holdup detection and multi-height electrode conductance sensors (CSMHEs) for cross-correlation velocity measurement. The microstrip array design of the FMAA ensures a more uniform electric field distribution, effectively mitigating the influence of nonuniform flow structures. The geometric dimensions of the FMAA are meticulously optimized through finite element analysis. Simulation reveals that the phase output exhibits high sensitivity to water holdup at 1.3 GHz. Dynamic oil-water flow experiments are conducted. The identification of four distinct flow patterns was achieved by analyzing real-time snapshots and synchronized output signals from both the FMAA and CSMHEs. Water holdup is determined by establishing mixed dielectric constant models for different flow patterns using the FMAA. The results indicate a strong correlation between the phase outputs of the FMAA and the water holdup, with a measurement error of 2.27%. Furthermore, a relationship was established between the cross-correlation velocity obtained from the CSMHEs and the mixture and oil superficial velocities. Additionally, by establishing drift-flux models for different flow patterns, the relationships among oil superficial velocity, water holdup, and mixture velocity are determined. Through the simultaneous solution, the prediction of mixture velocity and phase superficial velocities is ultimately achieved. The measurement error of superficial velocities of water and oil are 3.44% and 19.12%, respectively. This approach demonstrates an effective new methodology for measuring liquid-liquid flows.