Vortex shedding wet gas flowmeter and method of measuring wet gas flow

Abstract

The application discloses a vortex throttle wet gas flowmeter, which comprises a measuring pipe, a vortex generator, a frequency and temperature composite sensor and a differential pressure tapping hole are sequentially arranged in the measuring pipe along the fluid flow direction, a frequency and temperature composite transmitter is fixedly connected to the frequency and temperature composite sensor, an intelligent differential pressure flow transmitter is arranged above the frequency and temperature composite transmitter, the frequency and temperature composite transmitter and the intelligent differential pressure flow transmitter are connected through a signal line, and the differential pressure tapping hole and the intelligent differential pressure flow transmitter are connected through a pressure tapping pipe. By reasonably designing the inner diameter of the measuring pipe, the gas-liquid stratification is avoided when the wet gas flows through the measuring pipe, and the gas-liquid mixing is more uniform. The application further discloses a wet gas flow measurement method. Different measurement methods are adopted under different liquid content conditions, the liquid phase measurement range of the flowmeter is improved, and the measurement requirement of large instantaneous liquid volume change of a bubble drainage well is met.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of flow measurement method, and particularly relates to a vortex throttling wet gas flowmeter, and further relates to a wet gas flow measurement method. BACKGROUND

[0002] At present, for the gas well with low single well production, the liquid cannot be normally carried by relying on the energy of the gas well, and a large number of gas wells need to be maintained in normal production by periodically adding foam drainage agent to the wellbore by manual or automatic way. The liquid production is unstable in the production process of the gas well, and the instantaneous liquid volume fluctuates from several hundred liters per day to several tens of cubic meters per day.

[0003] In order to master the real-time gas and liquid production change rule of the gas well, and provide a basis for optimization and fine management of the foam drainage gas recovery measure system, a conical orifice plate gas-liquid two-phase flowmeter (publication number: CN204255415U; publication date: April 8, 2015) and a vortex throttling integrated gas-liquid two-phase flowmeter (publication number: CN208953029U; publication date: June 7, 2019) are used in succession to realize online continuous measurement of gas-liquid two-phase without separation. The conical orifice plate gas-liquid two-phase flowmeter adopts differential pressure noise measurement principle, that is, the differential pressure before and after the throttling element is collected at high speed, the differential pressure fluctuation amplitude value (i.e. the relative differential of the square root of the differential pressure) is calculated to calculate the liquid content rate, and then the gas and liquid flow rates are obtained. The technology is only applicable to wet gas measurement with low liquid content rate (mass liquid content rate less than 30%) and relatively stable instantaneous gas volume. For the section with large liquid volume, the liquid phase measurement error is large due to large gas volume fluctuation. The vortex throttling integrated gas-liquid two-phase flowmeter measures the average density of wet gas by combining the vortex flowmeter and the throttling flowmeter, and calculates the gas and liquid two-phase flow rates by combining the gas and liquid single-phase densities. The technology is applicable to wet gas measurement with mass liquid content rate in the range of 20%-90%. If the mass liquid content rate is out of the range, the measurement error is large due to too small difference between the average density of the measured wet gas and the pure gas or pure liquid density. At the same time, the measurement principle of the above two flowmeters requires that the gas and liquid are mixed uniformly, and the measurement error is large for gas and liquid stratified flow. In addition, due to the fixed error of the sensor, a small amount of liquid is measured in the pure gas working condition, which affects the cumulative liquid volume measurement error of the flowmeter. SUMMARY

[0004] The purpose of the present application is to provide a vortex throttling wet gas flowmeter, which avoids gas and liquid stratification when wet gas flows through the measuring pipe by reasonably designing the inner diameter of the measuring pipe, so that the gas and liquid are mixed uniformly.

[0005] Another purpose of the present application is to provide a wet gas flow measurement method, which expands the measurement range of the flowmeter by using different measurement methods at different mass liquid content rates.

[0006] The first technical solution of the present application is a vortex throttle wet gas flowmeter, which comprises a measuring pipe, a vortex generator arranged in the measuring pipe along the fluid flow direction, a frequency and temperature composite sensor, one end of the frequency and temperature composite sensor penetrating out of the measuring pipe, a differential pressure tapping hole opened on the wall of the measuring pipe, a frequency and temperature composite transmitter arranged at the end of the frequency and temperature composite sensor penetrating out of the measuring pipe, an intelligent differential pressure flow transmitter arranged above the frequency and temperature composite transmitter, the frequency and temperature composite transmitter and the intelligent differential pressure flow transmitter being connected through a signal line, and a pressure tapping pipe arranged in the differential pressure tapping hole, the other end of the pressure tapping pipe being connected to the intelligent differential pressure flow transmitter.

[0007] The first technical solution of the present application is further characterized in that,

[0008] The two ends of the measuring pipe are connected by flanges.

[0009] The vortex generator and the temperature composite sensor are both arranged between the two differential pressure tapping holes.

[0010] Two differential pressure tapping holes are arranged in the measuring pipe.

[0011] The vortex generator is arranged upstream of the frequency and temperature composite sensor.

[0012] The flow velocity of the wet gas in the measuring pipe is greater than or equal to 15 m / s.

[0013] The second technical solution of the present application is a wet gas flow measurement method, which comprises the following steps:

[0014] Step 1: the wet gas coming out of the wellbore passes through the vortex generator;

[0015] Step 2: the fluid generates vortexes after the vortex generator and differential pressures are generated before and after the vortex generator;

[0016] Step 3: the frequency and temperature composite sensor measures the vortex frequency and the fluid temperature analog signals in real time;

[0017] Step 4: the vortex frequency and the fluid temperature analog signals obtained in step 3 are transmitted to the frequency and temperature composite transmitter to be converted into digital signals;

[0018] Step 5: the digital signals obtained in step 4 are transmitted to the intelligent differential pressure flow transmitter through the signal line;

[0019] Step 6: the intelligent differential pressure flow transmitter collects the differential pressure and static pressure signals in real time through the pressure tapping pipe and collects the frequency and temperature signals through the signal line;

[0020] Step 7: the gas-liquid instantaneous flow is calculated through the built-in calculation program.

[0021] The second technical solution of the present application is further characterized in that,

[0022] The specific steps of the calculation of Step 7 are as follows:

[0023] Step 7.1, calculate the inner diameter of the measuring tube according to formula (1),

[0024]

[0025] In formula (1), Q0 is the critical liquid-carrying flow rate of the gas well, with the unit of m 3 / s; d is the inner diameter of the measuring tube, with the unit of m;

[0026] Step 7.2, calculate the wet gas volume flow rate according to formula (2),

[0027]

[0028] In formula (2), Q v is the wet gas volume flow rate; A is the cross-sectional area of the measuring tube; f is the vortex frequency; d is the characteristic width of the vortex generator; and St is the Strouhal number, dimensionless;

[0029] Step 7.3, calculate the instantaneous gas-liquid flow rate:

[0030] When the measured wet gas volume flow rate Q v is less than the critical liquid-carrying flow rate Q0 of the gas well, the flowmeter automatically processes as pure gas, and outputs the instantaneous gas volume Q g equal to Q v , and the instantaneous liquid volume Q l is 0;

[0031] When the measured wet gas volume flow rate Q v is greater than or equal to the critical liquid-carrying flow rate Q0 of the gas well, the instantaneous gas-liquid flow rate is calculated according to formulas (3) and (4),

[0032]

[0033]

[0034] In formulas (3) and (4), Q is the volume flow rate, k is the correction coefficient, subscript l is the liquid phase, subscript g is the gas phase, ρ g is the gas working density, ρ l is the liquid density, Q v is the wet gas volume flow rate, and ρ is the wet gas flow density, whose calculation formula is shown in formula (5);

[0035]

[0036] In formula (5), C is the outflow coefficient, A1 is the flow area at the vortex generator, A2 is the cross-sectional area of the measuring tube, ε is the expansion coefficient, d is the inner diameter of the measuring tube, and ΔP is the differential pressure.

[0037] Step 7.4: Based on the calculation results in Step 2.2, calculate the mass liquid content X according to Equation (6). l ,

[0038]

[0039] Step 7.5, calculate the instantaneous gas-liquid flow rate:

[0040] Step 7.5.1, when the mass liquid content X l When the flow rate is greater than or equal to 25%, the instantaneous flow rate of gas and liquid output by the flow meter is the instantaneous flow rate calculated in step 7.5.2;

[0041] Step 7.5.2, when the mass liquid content X l When the flow rate is less than 25%, the flow meter calculates the instantaneous gas-liquid flow rate according to equations (7) and (8).

[0042]

[0043]

[0044] In equations (7) and (8), K g K l This is a correction factor;

[0045]

[0046]

[0047]

[0048]

[0049] Step 7.6, when Q g When the flow rate is less than the critical liquid-carrying flow rate Q0, it is treated as pure gas. The instantaneous gas flow rate is calculated according to step 6.2, and the instantaneous liquid flow rate is 0.

[0050] The beneficial effects of this invention are:

[0051] (1) The present invention uses the vortex generator directly as a throttling element and directly takes pressure before and after the vortex generator, thus avoiding the influence of setting a separate throttling element on the vortex frequency measurement.

[0052] (2) By rationally designing the inner diameter of the measuring tube, this invention ensures that the flow velocity of the fluid flowing through the measuring tube when the gas well produces liquid is not less than 15 m / s, the wet flow is mist-like, the mixing is relatively uniform, which is conducive to the accurate measurement of the flow meter, and the gas phase flow rate when the gas well produces liquid is greater than the critical liquid carrying flow rate.

[0053] (3) The present application expands the flow meter measurement range by using different measurement methods at different mass liquid content rates, ensures the field measurement effect, and makes it more suitable for field application. BRIEF DESCRIPTION OF DRAWINGS

[0054] Figure 1 is a production curve diagram of a typical foam drainage gas recovery well in the vortex throttle wet gas flow meter and wet gas flow measurement method of the present application;

[0055] Figure 2 is a structural schematic diagram of a vortex throttle wet gas flow meter in the vortex throttle wet gas flow meter and wet gas flow measurement method of the present application;

[0056] Figure 3 is a structural schematic diagram of a measuring pipe in the vortex throttle wet gas flow meter and wet gas flow measurement method of the present application;

[0057] Figure 4 is a use state diagram of a vortex throttle wet gas flow meter in the vortex throttle wet gas flow meter and wet gas flow measurement method of the present application;

[0058] Figure 5 is a flow chart of a vortex throttle wet gas flow measurement method in the vortex throttle wet gas flow meter and wet gas flow measurement method of the present application.

[0059] In the figure, 1. measuring pipe, 2. frequency and temperature composite transmitter, 3. pressure tapping pipe, 4. signal line, 5. intelligent differential pressure flow transmitter, 6. vortex generator, 7. frequency and temperature composite sensor, 8. differential pressure tapping hole, 9. measuring pipe body. DETAILED DESCRIPTION

[0060] The present application will be described in detail below in combination with the drawings and specific embodiments.

[0061] As shown in Figure 1 , the liquid production in the production process of a typical foam drainage gas recovery well is unstable, and the instantaneous liquid volume fluctuates from several hundred liters per day to several tens of cubic meters per day.

[0062] The vortex throttle wet gas flow meter of the present application has the structure as shown in Figure 2 , and mainly consists of a measuring pipe 1, a frequency and temperature composite transmitter 2, a pressure tapping pipe 3, a signal line 4, and an intelligent differential pressure flow transmitter 5.

[0063] As shown in Figure 3As shown, the vortex generator 6 is arranged in the measuring tube 1, and the frequency and temperature composite sensor 7 is arranged behind the vortex generator 6, and the differential pressure tapping holes 8 are arranged before and behind the vortex generator 6 and the frequency and temperature composite sensor 7, the vortex generator 6 generates vortexes for the fluid, and the vortex generator 6 is directly used as a throttling element, and the pressure is directly taken before and behind the vortex generator, so that the influence of the separately arranged throttling element on the vortex frequency measurement is avoided, the frequency and temperature composite sensor 7 measures the vortex frequency f and the fluid temperature T analog signals, and the analog signals are transmitted to the frequency and temperature composite transmitter 2, the frequency and temperature composite transmitter 2 converts the analog signals into digital signals, and the digital signals are transmitted to the intelligent differential pressure flow transmitter 5 through the signal line 4, the intelligent differential pressure flow transmitter 5 collects the differential pressure ΔP and the static pressure p signals provided by the pressure tapping pipe 3 in real time, and the gas-liquid instantaneous flow is calculated in real time in combination with the frequency and temperature signals.

[0064] As shown in the figure, Figure 4 The vortex shedding throttling wet gas flowmeter is installed between a shut-off valve and a gate valve, one end of the shut-off valve is connected with a gas well head, and the gas well head is sequentially connected with the shut-off valve, the vortex shedding throttling wet gas flowmeter and the gate valve through a gas production pipeline.

[0065] The specific working principle of the wet gas flow measurement method is as follows:

[0066] Step 1, the wet gas from the gas well cylinder passes through the vortex generator 6;

[0067] Step 2, the fluid generates vortexes after the vortex generator 6, and differential pressures are generated before and after the vortex generator 6;

[0068] Step 3, the frequency and temperature composite sensor 7 measures the vortex frequency and the fluid temperature analog signals in real time;

[0069] Step 4, the vortex frequency and the fluid temperature analog signals in step 3 are transmitted to the frequency and temperature composite transmitter 2 to be converted into digital signals;

[0070] Step 5, the digital signals obtained in step 4 are transmitted to the intelligent differential pressure flow transmitter 5 through the signal line 4;

[0071] Step 6, the intelligent differential pressure flow transmitter 5 collects the differential pressure and the static pressure signals in real time through the pressure tapping pipe 3, and collects the frequency and temperature signals through the signal line 4;

[0072] Step 7, the gas-liquid instantaneous flow is calculated through the built-in calculation program:

[0073] The inner diameter d of the measuring tube 1 of this invention is designed based on the working condition that the flow velocity of the humid gas is greater than or equal to 15 m / s when the gas well flows through the measuring tube under the critical liquid carrying flow rate Q0, as shown in equation (1). Under this flow velocity, the humid gas is a mist in the horizontal tube, and the gas-liquid mixture is relatively uniform, which is beneficial for accurate measurement. For a certain gas well, the critical liquid carrying flow rate is directly proportional to the production oil pressure. The oil pressure of the gas well does not change much in a certain production stage, and the critical liquid carrying flow rate can be regarded as a constant. When the gas volume of the gas well is less than the critical liquid carrying flow rate of the gas well, it is impossible to carry the liquid in the well to the surface. The fluid flowing through the flow meter can be regarded as pure gas. When the gas volume of the gas well is greater than the critical liquid carrying flow rate of the gas well, the fluid flowing through the flow meter is humid gas, that is, gas-liquid two-phase flow.

[0074]

[0075] In equation (1), Q0 is the critical fluid carrying capacity of the gas well, in m³ / s. 3 / s; d is the inner diameter of the measuring tube, in meters.

[0076] like Figure 5 As shown, the specific steps of the flow calculation method of the present invention are as follows:

[0077] Step 1: Calculate the volumetric flow rate of moisture using the moisture flow rate measurement method, as shown in equation (2).

[0078]

[0079] In equation (2): Q v denoted as ρ, where ρ is the volumetric flow rate of the moist gas; A is the cross-sectional area inside the measuring tube; f is the vortex frequency; d is the characteristic width of the vortex generator; and St is the Strouhal number, which is dimensionless.

[0080] Step 2: When measuring the moisture volumetric flow rate Q v When the flow rate is less than the critical liquid-carrying flow rate Q0 of the gas well, the flow meter automatically processes the flow as pure gas and outputs the instantaneous gas volume Q. g equals Q v Output instantaneous liquid volume Q l It is 0.

[0081] When measuring the moisture volume flow rate Q v When the gas well's critical liquid-carrying flow rate Q0 is greater than or equal to the gas well's critical flow rate, the instantaneous gas-liquid flow rate is calculated according to formulas (3) and (4). That is, the wet gas fluid density is calculated by using a combination of vortex flow meter and throttling flow meter, and the gas-liquid two-phase flow rate is obtained based on the gas-liquid single-phase density.

[0082]

[0083]

[0084] In formula (3) and (4), Q is the volume flow rate, k is the correction coefficient, subscript 1 is the liquid phase, and subscript g is the gas phase, ρ g is the gas working density, ρ l is the liquid density, Q v is the wet gas volume flow rate, and ρ is the wet gas fluid density, which is calculated according to formula (5),

[0085]

[0086] In formula (5), C is the outflow coefficient, A1 is the flow area at the vortex generator, A2 is the cross-sectional area of the measuring tube, ε is the expansion coefficient, d is the diameter of the measuring tube, and ΔP is the differential pressure.

[0087] Step 3: According to the calculation results of formula (3) and formula (4), the mass liquid content X l is calculated according to formula (6).

[0088]

[0089] When the mass liquid content X l is greater than or equal to 25%, the instantaneous flow rate of the flowmeter output gas and liquid is the instantaneous flow rate calculated according to formula (3) and formula (4).

[0090] When the mass liquid content X l is less than 25%, the flowmeter calculates the gas-liquid instantaneous flow rate according to formula (7) and formula (8), that is, the differential pressure noise method is used to measure the gas-liquid instantaneous flow rate according to the relationship between the differential pressure fluctuation amplitude (differential pressure square root relative variance) and the liquid content.

[0091]

[0092]

[0093] In the above formula, K g and K l are correction coefficients.

[0094]

[0095]

[0096]

[0097]

[0098] By using different measurement methods at different mass liquid contents, the measurement range of the flowmeter is expanded, the on-site measurement effect is guaranteed, and the on-site applicability is improved.

[0099] Step 4: When Q gWhen the liquid-carrying flow rate is less than the critical liquid-carrying flow rate Q0, the instantaneous gas flow rate is calculated according to formula (2) and outputted, and the instantaneous liquid flow rate is 0.

[0100] Embodiment 1

[0101] Firstly, the measuring pipe inner diameter of the flowmeter is designed according to the critical liquid-carrying flow rate of the gas well.

[0102] When the wet gas from the wellbore passes through the flowmeter after a series of bends and valves, the fluid will generate vortexes after the vortex generator 6 and generate differential pressure before and after the vortex generator 6. The frequency and temperature composite sensor 7 measures the vortex frequency and fluid temperature analog signals in real time and transmits them to the frequency and temperature composite transmitter 2 to convert them into digital signals. The intelligent differential pressure flow transmitter 5 collects the differential pressure and static pressure signals in real time through the pressure tapping pipe 3 and collects the frequency and temperature signals through the signal line 4. The gas-liquid instantaneous flow rate is calculated through the built-in calculation program, and the specific calculation steps are as follows:

[0103] Step 1: Calculate the wet gas volume flow rate using the wet gas flow rate measurement method, as shown in formula (2).

[0104]

[0105] In formula (2), Q v is the wet gas volume flow rate; A is the measuring pipe cross-sectional area; f is the vortex frequency; d is the vortex generator characteristic width; and St is the Strouhal number, which is dimensionless.

[0106] Step 2: Calculate the gas-liquid instantaneous flow rate:

[0107] When the measured wet gas volume flow rate Q v is less than the critical liquid-carrying flow rate Q0 of the gas well, the flowmeter automatically processes the pure gas, and the instantaneous gas flow rate Q g is equal to Q v , and the instantaneous liquid flow rate Q l is 0.

[0108] Embodiment 2

[0109] Firstly, the measuring pipe inner diameter of the flowmeter is designed according to the critical liquid-carrying flow rate of the gas well.

[0110] When the wet gas from the wellbore passes through the flowmeter after a series of bends and valves, the fluid will generate vortexes after the vortex generator 6 and generate differential pressure before and after the vortex generator 6. The frequency and temperature composite sensor 7 measures the vortex frequency and fluid temperature analog signals in real time and transmits them to the frequency and temperature composite transmitter 2 to convert them into digital signals. The intelligent differential pressure flow transmitter 5 collects the differential pressure and static pressure signals in real time through the pressure tapping pipe 3 and collects the frequency and temperature signals through the signal line 4. The gas-liquid instantaneous flow rate is calculated through the built-in calculation program, and the specific calculation steps are as follows:

[0111] Step 1, calculate the wet gas volume flow rate by using the wet gas flow rate measurement method, see equation (2).

[0112]

[0113] In equation (2), Q v is the wet gas volume flow rate; A is the cross-sectional area of the measuring tube; f is the vortex frequency; d is the characteristic width of the vortex generator; St is the Strouhal number, dimensionless.

[0114] Step 2, when the measured wet gas volume flow rate Q v is greater than or equal to the critical liquid-carrying flow rate Q0of the gas well, calculate the gas-liquid instantaneous flow rate according to equations (3) and (4);

[0115]

[0116]

[0117] In equations (3) and (4), Q is the volume flow rate, k is the correction coefficient, subscript l is the liquid phase, subscript g is the gas phase, ρ g is the gas operating density, ρ l is the liquid density, Q v is the wet gas volume flow rate, and ρ is the wet gas fluid density, which is calculated as follows,

[0118]

[0119] In equation (5), C is the outflow coefficient, A1 is the flow area at the vortex generator, A2 is the cross-sectional area of the measuring tube, ε is the expansion coefficient, d is the diameter of the measuring tube, and ΔP is the differential pressure.

[0120] Step 3, according to the calculation results of equations (3) and (4), calculate the mass liquid holdup X l according to equation (6).

[0121]

[0122] Step 4, when the mass liquid holdup X l is greater than or equal to 25%, the instantaneous flow rate output by the flowmeter is the instantaneous flow rate calculated in step 2.

[0123] Example 3

[0124] First, according to the critical liquid-carrying flow rate of the gas well, design the measuring tube inner diameter of the flowmeter according to equation (1).

[0125] When the wet gas from the wellbore passes through the flowmeter after a series of bends and valves, the fluid will generate vortexes after the vortex generator 6 and generate differential pressure before and after it. The frequency and temperature composite sensor 7 measures the vortex frequency and fluid temperature in real time and transmits the analog signals to the frequency and temperature composite transmitter 2 to convert them into digital signals. The intelligent differential pressure flow transmitter 5 collects the differential pressure and static pressure signals in real time through the pressure tapping pipe 3 and collects the frequency and temperature signals through the signal line 4, and calculates the gas-liquid instantaneous flow rate through the built-in calculation program. The specific calculation steps are as follows:

[0126] Step 1, calculate the wet gas volume flow rate according to formula (2),

[0127]

[0128] In formula (2), Q v is the wet gas volume flow rate; A is the cross-sectional area of the measuring pipe; f is the vortex frequency; d is the characteristic width of the vortex generator; and St is the Strouhal number, which is dimensionless.

[0129] Step 2, when the measured wet gas volume flow rate Q v is greater than or equal to the critical liquid-carrying flow rate Q0 of the gas well, calculate the gas-liquid instantaneous flow rate according to formulas (3) and (4);

[0130]

[0131]

[0132] In formulas (3) and (4), Q is the volume flow rate, k is the correction coefficient, subscript l is the liquid phase, subscript g is the gas phase, ρ g is the gas working density, ρ l is the liquid density, Q v is the wet gas volume flow rate, and ρ is the wet gas flow density, whose calculation formula is shown in formula (5),

[0133]

[0134] In formula (5), C is the outflow coefficient, A1 is the flow area at the vortex generator, A2 is the cross-sectional area of the measuring pipe, ε is the expansion coefficient, d is the diameter of the measuring pipe, and ΔP is the differential pressure.

[0135] Step 3, according to the calculation results of formulas (3) and (4), calculate the mass liquid holdup X l according to formula (6),

[0136]

[0137] Step 4.2, when the mass liquid holdup X l is less than 25%, the flowmeter calculates the gas-liquid instantaneous flow rate according to the following formula,

[0138]

[0139]

[0140] In formula (7) and (8), K g , K l is a correction coefficient.

[0141]

[0142]

[0143]

[0144]

[0145] Example 4

[0146] First, according to the critical liquid-carrying flow rate of the gas well, the flowmeter measuring pipe diameter is designed according to formula (1).

[0147] When the wet gas from the gas well wellbore passes through the flowmeter after a series of bends and valves, the fluid will generate vortexes after the vortex generator 6, and differential pressure will be generated before and after the vortex generator 6. The frequency and temperature composite sensor 7 measures the vortex frequency and fluid temperature analog signals in real time and transmits them to the frequency and temperature composite transmitter 2 to convert them into digital signals. The intelligent differential pressure flow transmitter 5 collects the differential pressure and static pressure signals in real time through the pressure tapping pipe 3, and collects the frequency and temperature signals through the signal line 4, and calculates the gas-liquid instantaneous flow rate through the built-in calculation program. The specific calculation steps are as follows:

[0148] Step 1, calculate the wet gas volume flow rate according to formula (2),

[0149]

[0150] In formula (2), Q v is the wet gas volume flow rate; A is the cross-sectional area of the measuring pipe; f is the vortex frequency; d is the characteristic width of the vortex generator; and St is the Strouhal number, which is dimensionless.

[0151] Step 2, when the measured wet gas volume flow rate Q v is greater than or equal to the critical liquid-carrying flow rate Q0 of the gas well, calculate the gas-liquid instantaneous flow rate according to formulas (3) and (4);

[0152]

[0153]

[0154] In formulas (3) and (4), Q is the volume flow rate, k is the correction coefficient, subscript l is the liquid phase, and subscript g is the gas phase, and ρg ρg is gas density l ρ1 is liquid density v Q is wet gas volume flow rate, ρ is wet gas fluid density, and the calculation formula is shown in formula (5)

[0155]

[0156] In formula (5), C is a flow-out coefficient, A1 is a flow-through area at the vortex generator, A2 is an inner cross-sectional area of the measuring tube, ε is an expansion coefficient, d is an inner diameter of the measuring tube, and ΔP is a differential pressure.

[0157] Step 3, according to the calculation result of (3), formula (4), the mass liquid rate X is calculated according to formula (6) l

[0158]

[0159] Step 4.2, when the mass liquid rate X l is less than 25%, the flowmeter calculates the gas-liquid instantaneous flow rate according to formula (7), formula (8)

[0160]

[0161]

[0162] In formula (7), formula (8), K g , K l are correction coefficients.

[0163]

[0164]

[0165]

[0166]

[0167] Step 5: when Q g is less than the critical liquid-carrying flow rate Q0, it is treated as pure gas, the instantaneous gas volume is calculated and output according to formula (2), and the instantaneous liquid volume is 0.

[0168] The present application improves the liquid phase measurement range of the flowmeter by reasonably designing the inner diameter of the measuring tube 1 of the flowmeter and ensuring that the gas-liquid flow state flowing through the measuring tube is mist flow when the instantaneous gas volume is greater than the critical liquid-carrying flow rate of the gas well, and by using different measurement methods under different liquid rate conditions, the wet gas meets the requirements of the field foam displacement well gas-liquid measurement.​

Claims

1. A method for measuring the flow rate of moisture using a vortex flow meter, comprising a measuring tube (1), wherein a vortex generator (6) and a frequency and temperature composite sensor (7) are provided inside the measuring tube (1) along the fluid flow direction, one end of the frequency and temperature composite sensor (7) extends out of the measuring tube (1), a differential pressure tapping hole (8) is opened on the wall of the measuring tube (1), a frequency and temperature composite transmitter (2) is provided at the end of the frequency and temperature composite sensor (7) extending out of the measuring tube (1), and an intelligent differential pressure flow transmitter (5) is provided above the frequency and temperature composite transmitter (2). The differential pressure flow transmitter (5) is connected via a signal line (4). A pressure tapping tube (3) is provided inside the differential pressure tapping hole (8), and the other end of the pressure tapping tube (3) is connected to the intelligent differential pressure flow transmitter (5). The flow velocity of the humid air in the measuring tube (1) is greater than or equal to 15 m / s. The two ends of the measuring tube (1) are connected by flanges. The vortex generator (6) and the temperature composite sensor (7) are both located between the two differential pressure tapping holes (8). The measuring tube (1) is provided with two differential pressure tapping holes (8). Along the direction of fluid movement, the vortex generator (6) is located upstream of the frequency and temperature composite sensor (7). The feature is that... Includes the following steps: Step 1: The wet gas coming out of the gas well shaft passes through the vortex generator (6). Step 2: The fluid generates vortices behind the vortex generator (6) and generates a differential pressure before and after the vortex generator (6); Step 3: The frequency and temperature composite sensor (7) measures the vortex frequency and fluid temperature simulation signal in real time; Step 4: Transmit the vortex frequency and fluid temperature analog signals described in Step 3 to the frequency and temperature composite transmitter (2) to convert them into digital signals. Step 5: The digital signal obtained in step 4 is transmitted to the intelligent differential pressure flow transmitter (5) through the signal line (4). Step 6: The intelligent differential pressure flow transmitter (5) collects differential pressure and static pressure signals in real time through the pressure tapping tube (3), and collects frequency and temperature signals through the signal line (4); Step 7: Calculate the instantaneous gas-liquid flow rate using the built-in calculation program; The specific steps for calculating step 7 are as follows: Step 7.1, calculate the inner diameter of the measuring tube according to formula (1). （1） In equation (1), Q0 is the critical fluid carrying capacity of the gas well, in m³ / s. 3 / s; d is the inner diameter of the measuring tube, in meters; Step 7.2, calculate the moisture volumetric flow rate according to equation (2). （2） In equation (2): Q v denoted as ρ, where ρ is the volumetric flow rate of the moist gas; A is the cross-sectional area inside the measuring tube; f is the vortex frequency; d is the characteristic width of the vortex generator; St is the Strouhal number, dimensionless. Step 7.3, calculate the instantaneous gas-liquid flow rate: Step 7.3.1, when measuring the moisture volume flow rate Q v When the flow rate is less than the critical liquid-carrying flow rate Q0 of the gas well, the flow meter automatically processes the flow as pure gas and outputs the instantaneous gas volume Q. g equals Q v Output instantaneous liquid volume Q l =0; Step 7.3.2, when measuring the moisture volume flow rate Q v When the gas well's critical liquid-carrying flow rate Q0 is greater than or equal to the gas well's critical liquid-carrying flow rate, the instantaneous gas-liquid flow rate is calculated according to equations (3) and (4). （3） （4） In equations (3) and (4): Q is the volumetric flow rate, k is the correction coefficient, subscript l represents the liquid phase, and subscript g represents the gas phase. For gas operating conditions, Let Q be the liquid density and Qv be the moisture volumetric flow rate. The density of the moist fluid is calculated using formula (5). （5） In equation (5), Here, A1 is the outflow coefficient, A2 is the flow area at the vortex generator, and A2 is the cross-sectional area inside the measuring tube. coefficient of thermal expansion To measure the inner diameter of the tube, Differential pressure; Step 7.4: Based on the calculation results in Step 2.2, calculate the mass liquid content X using the following formula. l , （6） Step 7.5, calculate the instantaneous gas-liquid flow rate: Step 7.5.1, when the mass liquid content X l When the flow rate is greater than or equal to 25%, the instantaneous flow rate of gas and liquid output by the flow meter is the instantaneous flow rate calculated in step 7.5.2; Step 7.5.2, when the mass liquid content X l When the flow rate is less than 25%, the flow meter calculates the instantaneous gas-liquid flow rate according to equations (7) and (8). （7） （8） In equations (7) and (8), K g K l This is a correction factor; Step 7.6, when Q g When the flow rate is less than the critical liquid-carrying flow rate Q0, it is treated as pure gas. The instantaneous gas flow rate is calculated according to step 6.2, and the instantaneous liquid flow rate is 0.

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