Study On Phase Fraction Measurement Of Two-phase Flow With High Water Cut Based On Coaxial Conductance Sensor

With the development of society and economy, the demand for crude oil is increasing rapidly. More and more oilfields have entered into the stage of exploitation with high water cut. The water cut of the crude oil in some oil well is up to 90%. The measuring technique of water cut plays an important role in crude production, storage, transportation, dehydration, processing and sale.There are significant differences in the electrical impedance properties between water and oil. The conductivity of oil is about 10^-6μS/cm, while that of groundwater is 10³μS/cm. The whole conductivity of mixture changes with the water cut. According to this property, the thesis developed a measuring technique for water content of crude.The main work completed is summarized as follows:1. As for the fraction measurement of two-phase flow with high water cut, the measuring method based on conductibility property was presented in this paper. The relationships between water content and the real part and the imaginary part of the mixture's impedance were validated and a electrical model of water-oil two phase flow was established.2. Considering the effects of slip, pressure losses and electric field distributions, the structure of the sensor was optimized.3. Based on the method of modularization, the thesis optimizes the preliminary measurement system. Impedance measurement module was redesigned in order to measure the change of low impedance accurately.4. The static experiment and the dynamic state experiment were implemented. The experiment results showed that this technique possessed the advantages of high precision, wider measuring range and shorter sampling time.Finally, some favorable suggests and prospects on the following research of this aspect are put forward.