Measurement Of Oil-Gas-Water Three-Phase Flow Based On Combined Electrical Sensors

Oil-gas-water flows widely exist in the processes of oil and gas exploitation.Research on the measurement of production profiles in oil wells has important academic value and practical significance.For the water continuous oil-gas-water flows,due to the interaction and slippage effect among phases,the structures of oil-gas-water flows are very complex,and the distributions of velocity and concentration are extremely non-uniform.Moreover,the salinity of produced water usually varies in the well because of the different salinity of formation water in different areas and the salinity changes during the oil well production.Variable salinity changes the water conductivity and water permittivity.All these characteristics bring great challenge to the production profile logging of oil-gas-water flows.The present research has achieved the following innovative achievements:1.A combined method to achieve salinity independent water holdup measurement is proposed.This method uses a constant voltage as the exciting signal and demodulates the current in sensor to obtain the conductivity,which ensures an optimal linear relationship between the response of sensor and conductivity.Through the design of online water conductivity measurement system,the automatic compensation of water conductivity in water holdup measurement is realized,and the influence of salinity on measurement is eliminated.In the aspect of mixture velocity measurement,the measurement accuracy of cross-correlation velocity is improved by using interpolation method.On the basis of flow pattern identification,the mixture velocity measurement of oil-gas-water three-phase flow is realized by using the kinematic wave model.2.A coaxial three-electrode distributed conductance sensor is proposed to achieve liquid film thickness measurement.Based on the strategy of simultaneously acquiring the outputs of two receiving electrodes and obtaining their ratio,a salinity and oil content independent measurement model of liquid film thickness is established.Then,salinity and oil content independent measurement of liquid film thickness is realized.Based on the simultaneous measurement of conductivity of oil-water mixture and conductivity of oil-gas-water mixture using liquid film sensor and water holdup sensor,respectively,a new gas holdup measurement model based on flow structure is established.It provides a new way to measure the gas holdup of oil-gas-water three-phase flow using the combined electrical sensors.3.A microwave water holdup measurement method based on microstrip antenna is proposed.Under the condition of water conductivity change,the dielectric properties of the mixture are simultaneously sensed by the physical sensitive effect including amplitude attenuation and phase shift of electromagnetic radiation propagating through the mixture.Based on the simultaneous acquisition of microwave amplitude attenuation and phase shift information,a novel decoupling method is investigated to obtain the water holdup and water conductivity simultaneously.Finally,salinity independent water holdup measurement using microwave method is achieved.4.A traversable bi-optical fiber probe and its measurement system are designed.The gas structure characteristics and flow parameter distribution of oil-gas-water flows are obtained.Combined with the upstream and downstream signals of the arc-type conductance sensors,the local and overall flow complexity of oil-gas-water flows are revealed using multi-scale cross entropy algorithm.The rotating electric field conductance sensor is applied to acquire the multi-channel signals from different positions of the pipe cross section.And the conjoint analysis based on multi-resolution analysis of wavelet transformation and multivariate weighted multi-scale permutation entropy is proposed,which can effectively uncover the flow instability of oil-gas-water flows,the nonlinear dynamic behavior of different scale structures and their internal relations.