Oil-Gas-Water Multiphase Flow Velocity Measurement With Ultrasonic And Electrical Dual-Modality Sensors

Multiphase flow is a common flow phenomenon encountered in nature and industries,and is important to the safety as well as stability in industrial process.The reasonable description of the flow regime and the accurate measurement of the key parameters is the core to understand and solve the multiphase flow problems.For the complex medium composition and flow regime,the accurate measurement for the flow process prameters is difficult.As a result,traditional measurment methods based on single modality are difficult to obtain the accurate flow process prameters.Hence,the development of the multi-modality technique provides an accurate measurement of multiphase flow process prameters.The present study proposed a new measurement method of multiphase flow process prameters based on the fluid medium characteristics and flow regime analysis,by taking the test mechanism of ultrasonic and electrical into consideration and combining the experiment as well as the mechanism analysis,the study of horizontal oil-gas-water multiphase flow velocity measurement with ultrasonic and electrical two modalities was carried out.The main work has been finished as following.(1)After summarizing and analyzing the measurement techniques of oil-gas-water multiphase flow,a flow velocity measurement method based on ultrasonic/electrical dual-modality sensor is presented.The conductance-capacitance electrical sensor was used for obtaining the phase fraction,and the continuous wave ultrasonic Doppler sensor was used for obtaining the dispersion phase velocity.Combining the phase fraction and the Doppler velocity,and analyzing the flow structure and process,a measurement model was bulit to obtain the overall superficial flow velocity and the individual superficial velocities of multiphase flow.(2)Designed an ultrasonic and electrical dual-modality test system,and conducted dynamic experiments of oil-water two phase flow,gas-water two-phase flow and oil-gas-water three-phase flow on a multiphase flow loop,which provides experimental data to the flow velocity measurement with the proposed system.(3)Based on the experimental data analysis of oil-water and gas-water two-phase flow,and aimed at the phase fraction required in the flow velocity measurement model,a conductance and capacitance combination method for measuring the water holdup and its model is proposed.In oil-water two-phase flow,the conductance modality works when the continuous phase is water;the capacitance modality works when the continuous phase is oil.In water continuous gas-water two-phase flow,the conductance modality works.The experiment results show that the presented method and model can realize the accurate water holdup measurement in oil-water two phase flow and water continuous gas-water two-phase flow.(4)For the oil-water two-phase flow,a model combining the one-side continuous wave ultrasound Doppler with the conductance-capacitance method is proposed.After flow structure analysis and based on the power law flow velocity profile,the non-slip and slip assumption theoretical correlations were built to relate the overall superficial velocity of oil-water two-phase flow with the measured Doppler velocity.The experimental results show that the proposed method estimates the overall superficial flow velocity with relative measurement error within 3%.(5)For the gas-liquid two-phase flow,a measurement method combined one-side continuous wave ultrasound Doppler method with the conductance modality is proposed.Three flow patterns(bubble flow,plug flow and slug flow)were studied.Taking the slip between gas and water into consideration,the measurement model is built based on a two-fluid model.After combining the water holdup,the flow velocity of air and water can be obtained.For slug flow,a correlation to calculate the overall superficial flow velocity was built based on a slug closure model.The experimental results show that the mean relative error can achieve within 4%.(6)For the horizontal oil-gas-water three-phase flow,a one-side continuous wave ultrasound Doppler method is proposed.Two typical flow patterns(water dominated dispersed plug flow,oil dominated dispersed plug flow)were studied.The one-sided ultrasound Doppler sensor was used to acquire the average flow velocity of the dispersed phases.By analyzing the momentum balance between different phases and modifying a two-fluid model into three-phase flow,a novel theoretical correlation to estimate the phase superficial velocity was established.The experimental results show that the relative measurement error can achieve within 4%.