Modeling and applications of Differential Dielectric Sensor (DDS) for multiphase measurement

Although several technologies for water cut measurement are available to provide solutions for the oil and gas industry, it is still necessary to improve the accuracy, to generalize applications and to reduce the cost of measurement. Predominantly, the existing water cut measurement technologies depend on empirical models or correlations which are labor intensive and time consuming. Also, frequent calibrations are usually required to compensate for the effects of temperature, salinity, oil density, emulsion status and flow regimes. Droplet size, which greatly affects composition measurement, has not been compensated for in the existing technologies, resulting in significant uncertainties.;This research effort aims to employ an analytical approach to develop a measurement model for the use of Differential Dielectric Sensor (DDS) for water cut measurement. The analytical approach is believed to be superior to empirical models and correlations commonly used throughout the area of multiphase metering in reducing the cost of sensor optimization in time and money. The analytical approach also can make it possible to overcome the need for frequent calibrations under field conditions.;The DDS measurement model includes a dielectric mixture model which calculates the average dielectric permittivity of a water/oil or oil/water mixture and sensor model which calculates attenuation and phase. Two sensor models are developed in this work for rectangular DDS and circular DDS respectively. The sensor model for circular DDS is an improved version of Xiang's (2007) model with appropriate treatment of the boundary conditions inside DDS. The improved sensor model successfully removes all the empirical coefficients used in Xiang's model and is generally valid for all conditions. The effects of droplet size on composition measurement have been discovered and can be compensated for by the developed dielectric mixture model in this work. The dielectric mixture model is developed in this study by introducing the scattering effects of microwave due to the suspended particles into Hanai dielectric mixture model (1960).;A comprehensive experimental program is conducted in order to investigate the effects of temperature, salinity and shear rate or droplet size. A lookup table approach associated with an appropriate searching algorithm is employed to convert differential attenuation and differential phase into water cut, droplet size and average dielectric permittivity simultaneously. Good agreement has been reached between DDS and additional measurement devices. A systematic uncertainty analysis is presented in this report that describes the factors contributing to the overall uncertainty of DDS technology, including manufacturing uncertainty and measurement uncertainty. However, the uncertainty of the measurement model is left to future work.;This work provides users powerful tools for composition measurement and process control by compensating the effect of droplet size, temperature, salinity and oil density. The challenge of composition measurement can be overcome with the help of the measurement model. Also, the unique capability of DDS has been created to simultaneously report the measurement of composition and mean droplet size of mixture fluids.