Multi-channel Method For Measuring Two-phase Flow In Oil And Gas Wells

Two-phase flow is a dual flow pattern in the production process of oil and gas wells.The accurate measurement of its flow rate is a major basis for observing the production status of oil and gas wells,evaluating the productivity of oil and gas wells and analyzing the dynamic changes of reservoirs,which is significant for adjusting production and optimizing production.Because the flow of two-phase flow in a pipeline is a non-stationary process and the flow pattern is complex and diverse,it is more difficult to accurately measure the parameters of two-phase flow.In view of the advantages of ultrasound in flow measurement,this paper adopts the ultrasonic measurement system,focusing on the multi-channel measurement method to solve the problem of extreme uncertainty in two-phase flow measurement.In order to achieve high-precision flow measurement,it is necessary to optimize the characteristic parameters of the ultrasonic sensor.For improving the ultrasonic penetration ability,choosing appropriate characteristic parameter for different measurement environments are necessary.According to assorted ultrasonic measurement methods,the appropriate structure of multi-channel sensor is designed,and the corresponding mathematical model of multi-channel flow measurement is established.FLUENT software is used to simulate the flow characteristics of gas-liquid and solid-liquid two-phase flow,which is utilized as a basis for multi-channel measurement.The simulation results show that the velocity distribution in the two-phase flow tube is uniform,the velocity in different layers is changed,and the stratification phenomenon becomes more obvious with the increase of pipe diameter,which indicates the necessary condition for multi-channel measurement.Multichannel measurement method can accurately describe the overall flow velocity in the tube by measuring the flow velocity information of unique channels,and compensate each other between the measurement results of each channel.Compared with the mono-channel measurement,it improves the measurement accuracy and reduces the rigorous requirements of the equipment for the flow field.According to the amplitude attenuation characteristics of the same frequency ultrasonic wave in altered fluid media,the theory and method of measuring the ratio by an ultrasonic wave in the case of gas-liquid stratified flow are studied in the study.After the ultrasonic signal passes through the fluid with different liquid level heights in the tube,the amplitude of the echo signal is collected by the peak detection,and the linear relationship between the detection amplitude and the liquid level height is obtained,and the fitting degree is higher.If the liquid level is known,the corresponding liquid phase holdup can be computed according to the established mathematical model for identifying the proportion of horizontal pipelines,and then the volume fraction of gas and liquid phases can be achieved.Analyzing the results,we can obtain that absolute error is less than 2.5 percentage points and the relative error is less than 5.2%.The measurement accuracy is high and the expected effect is achieved.On the basis of theoretical calculation and simulation research,aiming at the gas-liquid two-phase flow research being conducted,the hardware circuit of three-channel ultrasonic flow measurement based on time difference method is designed.At the same time,debugged and matched with corresponding software program,and a simple experiment platform is built-in the laboratory to verify the overall design scheme.In the case of separate void fractions,the experimental data of different flow velocities of gas-liquid mixtures were measured,data processing and results analysis were performed,and the measurement results complied with the requirements of the subject assessment index for measurement accuracy.When the void fraction is 10%,the relative errors of the measurement results compare with those of the mono-channel measurement,and the error curves are brought.The experimental errors decrease by 2%~8.2%,which shows the superiority of the multi-channel measurement method.The research results have strong practicability and solved many knotty and practical problems in two-phase flow measurement over the years.