Superficial Dielectric Constant(SDC) model of gas-water flow in Resonant Cavity Sensor(RCS) based on flow regimes

Abstract

Water holdup measurement is always in the spotlight of the oil and gas industry. One way of determining water holdup in gas-liquid two-phase flow is through dielectric constant of flow. In this study, we proposed Superficial Dielectric Constant (SDC) and established the SDC model to describe the relationship between dielectric properties and water holdup. Firstly, we designed a Resonant Cavity Sensor(RCS), and the simulation models were established based on Ansys HFSS. Furthermore, a SDC simulation method based on rod-shaped material with HFSS was proposed. Totally 9 prototypes with different cavity D and bore diameters d were simulated with different water holdups ranging from 0 to 100%. Stratified distributed structure (SDS) and annular distributed structure (ADS), as two common flow regimes in gas-water flow, were included in the simulation and 198 data points were obtained. As a result, at a same water holdup, SDC of SDS was higher than that of ADS. At the same water holdup, with the decrease of D or the increase of d, SDC increased in SDS and decreased in ADS. Finally, SDC models of the two structures were established based on the two-thirds of simulation data. The remaining data points were utilized to verify models, the confidence probability of relative error in ±10% was 97% for SDS and the confidence probability of relative error in ±5% was 91% for ADS. In addition, the experimental validation was carried out with two dimensional prototypes under the two structures and the absolute values of relative error were lower than 10%. The results suggest that SDC model maybe provide potential for water holdup measurement in gas-liquid two-phase flow.