Gas-liquid online measurement method of differential pressure type vortex precession flowmeter

Abstract

The invention relates to the technical field of moisture measurement, in particular to a gas-liquid online measurement method of a differential pressure type vortex precession flowmeter. The invention relates to a gas-liquid online measurement method of a differential pressure type vortex precession flowmeter, which comprises the following steps of: respectively constructing a pressure difference ratio prediction model taking a pressure difference ratio as a dependent variable and a characteristic frequency prediction model taking a characteristic frequency as a dependent variable by taking a Loma parameter, a gas phase Froude number, a gas-liquid density ratio and a gas phase apparent velocity as independent variables; and substituting the test data in the experimental stage into the differential pressure ratio prediction model and the characteristic frequency prediction model to obtain a fitting coefficient, and further obtaining the field predicted gas phase flow and the field predicted liquid phase flow according to the test data in the field stage.

Description

Technical Field

[0001] The invention relates to the technical field of wet gas metering, and in particular to a gas-liquid online measurement method of a differential pressure swirl flowmeter. Background Art

[0002] At present, the online wet gas metering of two-phase flow without gas-liquid separation is mainly solved and calculated by establishing mathematical models, which mainly include three types: one is to use microwave and radio frequency to measure water content, and establish a virtual high or virtual low model for gas-liquid two-phase metering; the second is to use two flow meters with different principles in series to establish a virtual high or virtual low combined metering model for online solution and metering, mainly including differential pressure + differential pressure series, differential pressure + non-differential pressure series and other combinations; the third is to use regression algorithms such as neural networks and support vector machines to establish nonlinear mapping between each phase flow and characteristic parameters, and perform virtual measurement of gas and liquid. Different online metering methods have a certain scope of application.

[0003] In order to understand the real-time production changes of gas wells, the project team successively adopted the combined metering methods of swirling vortex + Venturi and swirling vortex + V-cone to solve the gas-liquid two-phase flow rate and realized online continuous metering of gas and liquid without separation; Xu Ying and others from Tianjin University adopted a dual model and installed differential pressure transmitters at both ends of the swirling vortex flowmeter. By measuring the pressure drop at both ends of the flowmeter, the two-phase metering of wet gas was realized by combining the precession frequency and pressure drop signal; the above measurement principles have high requirements on the range of gas and liquid volumes. When the gas production of the gas well is low and the liquid production fluctuates greatly, the metering error is large. Summary of the invention

[0004] The present invention aims to solve the above problems and proposes a gas-liquid online measurement method of a differential pressure vortex flowmeter.

[0005] The technical solution of the present invention is: A gas-liquid online measurement method for a differential pressure vortex flowmeter is proposed. The method takes the Loma parameter, gas phase Froude number, gas-liquid density ratio and gas phase apparent velocity as independent variables, and respectively constructs a pressure difference ratio prediction model with the pressure difference ratio as the dependent variable and a characteristic frequency prediction model with the characteristic frequency as the dependent variable. The test data of the experimental stage are substituted into the pressure difference ratio prediction model and the characteristic frequency prediction model to obtain the fitting coefficient, and then the field predicted gas phase flow rate and the field predicted liquid phase flow rate are obtained according to the field stage test data. The characteristic frequency prediction model is: f = a 1 v sg (1+ F rg c1 X LM DR d1 ) m1 ; The pressure difference ratio prediction model is: w = a 2(1+ F rg c2 X LM D R d2 ) m2 ; Where: f is the characteristic frequency, Hz; w is the pressure difference ratio, dimensionless; a 1. a 2. c 1. c 2. d 1. d 2. m 1. m 2 are all prediction model fitting coefficients, dimensionless; v sg is the gas phase superficial velocity, m / s; F rg is the gas phase Froude number, dimensionless; X LM is the Loma parameter, dimensionless; D R is the gas-liquid density ratio, dimensionless.

[0006] The test data of the experimental stage are obtained by testing the multiphase flow metering experimental platform; wherein the flowmeter in the multiphase flow metering experimental platform is a differential pressure swirl flowmeter; the throat diameter ratio of the differential pressure swirl flowmeter is β The value range is 0.3~0.7; the throat diameter ratio β = d / D ; Where: β is the throat diameter ratio of the differential pressure vortex flowmeter, dimensionless; d is the throat diameter of the differential pressure swirl flow, mm; D is the inner diameter of the pipe, mm.

[0007] The experimental phase test data includes: experimental phase characteristic frequency f 实验 , pressure difference ratio during the experimental stage w 实验 、 Gas flow rate during the experimental period Q g实验 , Liquid flow rate during the experimental phase Q l实验, differential pressure vortex flowmeter pressure difference between upstream and throat △ P 1. The pressure difference between the downstream and throat of the differential pressure vortex flowmeter △ P 2. Loma parameters in the experimental stage X LM实验 、 Gas phase Froude number during the experimental period F rg实验 、 Gas-liquid density ratio during the experimental stage D R实验 And the gas phase superficial velocity during the experimental period v sg实验 ; Perform nonlinear data fitting on several groups of test data in the experimental stage to obtain the fitting coefficient of the prediction model, and then obtain the characteristic frequency function and the pressure difference ratio function; The specific process of obtaining the test data in the experimental stage is as follows: a multiphase flow metering experimental platform is built, and its input end is a gas phase and a liquid phase; the gas phase and the liquid phase are fully mixed in the gas-liquid mixer and then enter the differential pressure vortex flowmeter to start the multiphase flow experimental test; The gas phase uses air as the medium, and the air is pressurized by an air compressor and then passes through a gas collecting tank, a dryer and a volume flowmeter to enter the gas-liquid mixer; the liquid phase uses water as the medium, and the water is pressurized by a centrifugal pump and then passes through a liquid phase mass flowmeter to enter the gas-liquid mixer; after the gas phase and the liquid phase are fully mixed in the gas-liquid mixer, they enter the differential pressure vortex flowmeter to start the multiphase flow experimental test; wherein, the volume flowmeter and the liquid phase mass flowmeter are both turbine flowmeters.

[0008] The specific process of obtaining the on-site predicted gas phase flow rate and the on-site predicted liquid phase flow rate is: combining the characteristic frequency function, the pressure difference ratio function, the Loma parameter X LM , gas phase Froude number F rg , gas-liquid density ratio D R , gas phase superficial velocity v sg Expression and volume liquid content LVF Substitute the field test data into the expression to solve the field predicted gas phase flow rate and field predicted liquid phase flow rate; The on-site test data specifically include: liquid density r l , gas phase density r g , measured value of characteristic frequency f 实测 And the measured value of pressure difference ratio w 实测 ; The Loma parameters XLM , gas phase Froude number F rg , gas-liquid density ratio D R , gas phase superficial velocity v sg Expression and volume liquid content LVF The expressions are: ; ; D R = r l / r g ; v sg =4 Q g / ( πD 2 ); LVF = Q l / ( Q l + Q g ) Where: LVF is the volume liquid content, dimensionless; r l is the liquid density, kg / m 3 ; r g is the gas phase density, kg / m 3 ; g is the acceleration due to gravity, generally taken as 9.8m / s 2 ; Q l To predict the liquid flow rate on site, m 3 ; Q g For the on-site prediction of gas phase flow, m 3 .

[0009] The technical effects of the present invention are: The present invention proposes a gas-liquid online measurement method for a differential pressure vortex flowmeter, and obtains a specific pressure difference ratio prediction model and a characteristic frequency prediction model by fitting the test data in the experimental stage; the characteristic frequency prediction model, the pressure difference ratio prediction model, the Loma parameter, the gas phase Froude number, the gas-liquid density ratio, the specific expression of the gas phase apparent flow velocity and the specific expression of the volume liquid content are combined, and substituted into the field stage test data to obtain the field predicted gas phase flow rate and the field predicted liquid phase flow rate. DETAILED DESCRIPTION

[0010] Example 1 A gas-liquid online measurement method for a differential pressure vortex flowmeter is proposed. The method takes the Loma parameter, gas phase Froude number, gas-liquid density ratio and gas phase apparent velocity as independent variables, and respectively constructs a pressure difference ratio prediction model with the pressure difference ratio as the dependent variable and a characteristic frequency prediction model with the characteristic frequency as the dependent variable. The test data of the experimental stage are substituted into the pressure difference ratio prediction model and the characteristic frequency prediction model to obtain the fitting coefficient, and then the field predicted gas phase flow rate and the field predicted liquid phase flow rate are obtained according to the field stage test data.

[0011] Example 2 On the basis of Example 1, it also includes: The characteristic frequency prediction model is: f = a 1 v sg (1+ F rg c1 X LM D R d1 ) m1 ; The pressure difference ratio prediction model is: w = a 2(1+ F rg c2 X LM D R d2 ) m2 .

[0012] Example 3 On the basis of Example 2, the invention further includes: The test data of the experimental stage is obtained through testing on a multiphase flow metering experimental platform; A multiphase flow metering experimental platform was built, with one gas phase and one liquid phase at its input end; the gas phase used air as the medium, and the air was pressurized by an air compressor and then passed through a gas collecting tank, a dryer and a volume flowmeter to enter the gas-liquid mixer; the liquid phase used water as the medium, and the water was pressurized by a centrifugal pump and then passed through a liquid mass flowmeter to enter the gas-liquid mixer; after the gas phase and the liquid phase were fully mixed in the gas-liquid mixer, they entered the differential pressure vortex flowmeter to start the multiphase flow experimental test, and the test data of the experimental stage was recorded; Several groups of test data from the experimental phases were subjected to nonlinear data fitting to obtain the fitting coefficients of the prediction model, and then the characteristic frequency function and the pressure difference ratio function were obtained.

[0013] Example 4 On the basis of Example 3, the invention further includes: The Loma parametersX LM , gas phase Froude number F rg , gas-liquid density ratio D R , gas phase superficial velocity v sg Expression and volume liquid content LVF The expressions are: ; ; D R = r l / r g ; v sg =4 Q g / ( πD 2 ); LVF = Q l / ( Q l + Q g ) Simultaneous characteristic frequency function, pressure difference ratio function, and Loma parameter X LM , gas phase Froude number F rg , gas-liquid density ratio D R , gas phase superficial velocity v sg Expression and volume liquid content LVF Expression, substitute the field test data (liquid density r l , gas phase density r g , measured value of characteristic frequency f 实测 And the measured value of pressure difference ratio w 实测 ), solve the on-site predicted gas phase flow rate and on-site predicted liquid phase flow rate.

[0014] A gas-liquid online measurement method for a differential pressure vortex flowmeter, the specific steps are as follows.

[0015] 1. Construct a differential pressure vortex flowmeter, which includes a venturi tube, a vortex generator and a de-vortex generator; the throat diameter of the differential pressure vortex flowmeter is d The inner diameter of the pipe is D , throat diameter ratio β = d / D ;Throat diameter ratio β The value range of is 0.3~0.7; in this embodiment, the throat diameter ratio β The value is 0.6; a piezoelectric ceramic is arranged at the throat of the Venturi tube to extract the frequency signal, which is used to obtain the characteristic frequency in the experimental stage f 实验 .

[0016] 2. Connect the differential pressure vortex flowmeter to the multiphase flow metering experimental platform; the input end of the multiphase flow metering experimental platform is one gas phase and one liquid phase; the gas phase uses air as the medium, and the air is pressurized by the air compressor and enters the gas-liquid mixer through the gas collecting tank, dryer and volume flowmeter; the liquid phase uses water as the medium, and the water is pressurized by the centrifugal pump and enters the gas-liquid mixer through the liquid mass flowmeter; the gas phase and the liquid phase are fully mixed in the gas-liquid mixer and enter the differential pressure vortex flowmeter to start the multiphase flow experiment test; record multiple groups of experimental stage test data under different operating environments, and each group of experimental stage test data specifically includes: experimental stage characteristic frequency f 实验 , pressure difference ratio during the experimental stage w 实验 、 Gas flow rate during the experimental period Q g实验 , Liquid flow rate during the experimental phase Q l实验 , differential pressure vortex flowmeter pressure difference between upstream and throat △ P 1. The pressure difference between the downstream and throat of the differential pressure vortex flowmeter △ P 2. Loma parameters in the experimental stage X LM实验 、 Gas phase Froude number during the experimental period F rg实验 、 Gas-liquid density ratio during the experimental stage D R实验 And the gas phase superficial velocity during the experimental period v sg实验 .

[0017] 3. Construct a pressure difference ratio prediction model with Roma parameter, gas phase Froude number, gas-liquid density ratio and gas phase superficial velocity as independent variables and pressure difference ratio as dependent variable, and a characteristic frequency prediction model with characteristic frequency as dependent variable; the characteristic frequency prediction model is specifically as follows: f = a 1 v sg (1+ F rg c1 X LM DR d1 ) m1 ; The specific pressure difference ratio prediction model is: w = a 2(1+ F rg c2 X LM D R d2 ) m2 ; The nonlinear data fitting of multiple groups of experimental phase test data obtained from the multiphase flow experimental test was performed to obtain the fitting coefficients of the prediction model as follows: a 1=32.18; c 1=0.64; d 1=0.55; m 1=-0.15; a 2=1.78; c 2=1.28; d 2=1.06; m 2=0.36; The characteristic frequency function is obtained as follows: f =32.18 v sg (1+ F rg 0.64 X LM D R 0.55 ) -0.15 ; The specific pressure difference ratio function is: w =1.78 (1+ F rg 1.28 X LM D R 1.06 ) 0.36 .

[0018] 4. Use the differential pressure vortex flowmeter for on-site stage measurement to obtain on-site stage test data; the on-site stage test data specifically includes: liquid phase density r l , gas phase density r g , measured value of characteristic frequency f 实测 And the measured value of pressure difference ratio w 实测; Combine the characteristic frequency function, pressure difference ratio function, Loma parameter, gas phase Froude number, gas-liquid density ratio, gas phase apparent flow rate expression and volume liquid content expression obtained in step 3 to solve the field predicted gas phase flow rate Q g and on-site prediction of liquid flow Q l .

[0019] Experimental results verify: A mathematical model was established based on experimental data and multiphase flow simulation data, 70% of which was used for model establishment and 30% for model verification. The basic data for model verification was obtained partly from experiments and partly from calculations of a 1:1 multiphase flow calculation model, which expanded the scope of application of the model. Finally, the frequency and pressure difference ratio of the field data test were brought into the mathematical model for iterative calculation to solve the gas phase flow rate and liquid phase flow rate, as shown in the following table: The differential pressure vortex flowmeter is installed at the wellhead of the on-site gas well. The natural gas containing liquid at the wellhead is first measured by the differential pressure vortex flowmeter; then the gas-liquid separation metering device is used for gas-liquid separation metering, and the gas phase is measured by the vortex flowmeter, and the liquid phase is measured by the float level meter. After the gas-liquid separation metering, the gas and liquid are mixed and transported to the gas gathering station through the gas production pipeline. The differential pressure vortex flowmeter and the skid-mounted gas-liquid separation metering device are installed in series, and the skid-mounted gas-liquid separation metering device is used as the standard device and the differential pressure vortex flowmeter is used as the test device. The results are compared and meet the error range requirements.

Claims

1. A method for online measurement of gas and liquid using a differential pressure vortex flowmeter, characterized in that: The pressure difference ratio prediction model with the pressure difference ratio as the dependent variable and the characteristic frequency prediction model with the characteristic frequency as the dependent variable were constructed respectively with the Loma parameter, gas phase Froude number, gas-liquid density ratio and gas phase superficial velocity as the independent variables; The test data of the experimental stage are substituted into the pressure difference ratio prediction model and the characteristic frequency prediction model to obtain the fitting coefficients, and then the field predicted gas flow rate and the field predicted liquid flow rate are obtained according to the test data of the field stage.

2. The method for online gas-liquid measurement of a differential pressure vortex flowmeter according to claim 1, characterized in that: The characteristic frequency prediction model is: f = a 1 v sg (1+ F rg c1 X LM D R d1 ) m1 ; The pressure difference ratio prediction model is: w = a 2(1+ F rg c2 X LM D R d2 ) m2 ; Where: f is the characteristic frequency, Hz; w is the pressure difference ratio, dimensionless; a 1. a 2. c 1. c 2. d 1. d 2. m 1. m 2 are the fitting coefficients of the prediction model, dimensionless; v sg is the gas phase superficial velocity, m / s; F rg is the gas phase Froude number, dimensionless; X LM is the Loma parameter, dimensionless; D R is the gas-liquid density ratio, dimensionless.

3. The method for online gas-liquid measurement of a differential pressure vortex flowmeter according to claim 1, characterized in that: The test data of the experimental stage are obtained by testing the multiphase flow metering experimental platform; wherein the flowmeter in the multiphase flow metering experimental platform is a differential pressure swirl flowmeter; the throat diameter ratio of the differential pressure swirl flowmeter is β The value range is 0.3~0.7; the throat diameter ratio β = d / D ; Where: β is the throat diameter ratio of the differential pressure vortex flowmeter, dimensionless; d is the throat diameter of the differential pressure swirl flow, mm; D is the inner diameter of the pipe, mm.

4. The method for online gas-liquid measurement of a differential pressure vortex flowmeter according to claim 3, characterized in that: The experimental phase test data includes: experimental phase characteristic frequency f 实验 , pressure difference ratio during the experimental stage w 实验 、 Gas flow rate during the experimental period Q g实验 , Liquid flow rate during the experimental phase Q l实验 , differential pressure vortex flowmeter pressure difference between upstream and throat △ P 1. The pressure difference between the downstream and throat of the differential pressure vortex flowmeter △ P 2. Loma parameters in the experimental stage X LM实验 、 Gas phase Froude number during the experimental period F rg实验 、 Gas-liquid density ratio during the experimental stage D R实验 And the gas phase superficial velocity during the experimental period v sg实验 ; Perform nonlinear data fitting on several groups of test data in the experimental stage to obtain the fitting coefficient of the prediction model, and then obtain the characteristic frequency function and the pressure difference ratio function.

5. The method for online gas-liquid measurement of a differential pressure vortex flowmeter according to claim 4, characterized in that: The specific process of obtaining the test data in the experimental stage is: building a multiphase flow metering experimental platform, whose input ends are one gas phase and one liquid phase; after the gas phase and the liquid phase are fully mixed in the gas-liquid mixer, they enter the differential pressure vortex flowmeter to start the multiphase flow experimental test.

6. The method for online gas-liquid measurement of a differential pressure vortex flowmeter according to claim 5, characterized in that: The gas phase uses air as the medium, and the air is pressurized by an air compressor and then enters the gas-liquid mixer through a gas collecting tank, a dryer and a volume flowmeter; the liquid phase uses water as the medium, and the water is pressurized by a centrifugal pump and then enters the gas-liquid mixer through a liquid mass flowmeter; after the gas phase and the liquid phase are fully mixed in the gas-liquid mixer, they enter the differential pressure vortex flowmeter to start the multiphase flow experimental test.

7. The method for online gas-liquid measurement of a differential pressure vortex flowmeter according to claim 6, characterized in that: The volume flowmeter and the liquid mass flowmeter are both turbine flowmeters.

8. The method for online gas-liquid measurement of a differential pressure vortex flowmeter according to claim 4, characterized in that: The specific process of obtaining the on-site predicted gas phase flow rate and the on-site predicted liquid phase flow rate is: combining the characteristic frequency function, the pressure difference ratio function, the Loma parameter X LM , gas phase Froude number F rg , gas-liquid density ratio D R , gas phase superficial velocity v sg Expression and volume liquid content LVF The expression is substituted into the field test data to solve the field predicted gas phase flow rate and the field predicted liquid phase flow rate.

9. The method for online gas-liquid measurement of a differential pressure vortex flowmeter according to claim 8, characterized in that: The on-site test data specifically include: liquid density ρ l , gas phase density ρ g , measured value of characteristic frequency f 实测 And the measured value of pressure difference ratio w 实测 .

10. The method for online gas-liquid measurement of a differential pressure vortex flowmeter according to claim 9, characterized in that: The Loma parameters X LM , gas phase Froude number F rg , gas-liquid density ratio D R , gas phase superficial velocity v sg Expression and volume liquid content LVF The expressions are: ； ； D R = ρ l / ρ g ； v sg =4 Q g / ( πD 2 )； LVF = Q l / ( Q l ＋ Q g ) Where: LVF is the volume liquid content, dimensionless; ρ l is the liquid density, kg / m 3 ; ρ g is the gas phase density, kg / m 3 ; g is the acceleration due to gravity, generally taken as 9.8m / s 2 ; Q l To predict the liquid flow rate on site, m 3 ; Q g For the on-site prediction of gas phase flow, m 3 .

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