Flow Measurement In Gas Liquid Two-Phase Flow Using Turbine Flowmeter And Conductance Sensor

Gas–liquid two-phase flow has been widely existed in oil well production and oil-gas transportation,parameter measurement of gas–liquid two-phase flow is of significant importance to scientific research and engineering technology,such as flowrate or water holdup.In this paper,a multi-parameters measurement method using turbine flowmeter combined conductivity sensor is proposed for the problem that the response of turbine flowmeter is seriously nonlinear when applied to gas-liquid two-phase flow measurement.Based on the volume model,mass model,momentum model and torque model,Instrument factor correction formulas of turbine flowmeter used in two-phase flow were established respectively,combined with the output frequency of the turbine flowmeter and the water holdup measured by conductance sensor,total flowrate measurement is realized.The research results obtained in this thesis are listed as follows:1)According to output response of turbine flowmeter and the water holdup measured by conductance sensor,the model tests of turbine flowmeter used in gas-liquid two-phase flow are carried out.It is found that total flowrate prediction accuracy of volumetric model is the lowest(absolute error 2.49m~3/day,relative error 12.41%).total flowrate prediction accuracy of mass model is improved(absolute error 2.36m~3/day,relative error 11.48%);momentum model has a higher total flowrate prediction accuracy(absolute error 1.97m~3/day,relative error 10.86%);The torque balance model has the best prediction accuracy due to the fact that radial distribution of the two-phase flow concentration is considered.2)Since all of the gas-liquid two-phase flow turbine flowmeter models contain an important key parameters-slip ratio,this thesis derives the slip ratio physical model from multiphase flow fluid mechanics;then,through carrying out dynamic experiment of gas-liquid two-phase flow,the distribution parameters of gas-liquid two-phase flow pattern in slip ratio physical model are identified,and the slip ratio parameters are provided for the establishment of gas-liquid two-phase flow turbine flowmeter measurement model based on flow pattern.3)Considering the influence of flow pattern on the measurement model of turbine flowmeter,this thesis proposes a magnitude and sign decomposition method to analysis the conductivity sensor signal.By extracting the scale index closely related to the flow pattern,Flow pattern identification is realized on the joint plane of magnitude and sign scale index;in addition,the multi-fractal singular spectrum is extracted from the conductivity sensor signal,and the stream identification is realized by extracting singular spectrum width and the singular spectrum amplitude difference(difference of fractal dimension).It provides a basis of flow identification for gas-liquid two-phase flow turbine flowmeter measurement models.