Oil-gas-water three-phase flow measuring device and method based on uniform-speed tube vortex street and microwave antenna

Abstract

The invention discloses an oil-gas-water three-phase flow measuring device and method based on a uniform-speed tube vortex street and a microwave antenna, and relates to the technical field of three-phase flow detection. The device comprises a bluff body, a pressure difference transmitter, a power divider and a microwave signal source, the bluff body is vertically placed at the central position in a target pipeline, two cavities, namely a high-pressure cavity and a low-pressure cavity, are formed in the bluff body, the high-pressure cavity and the low-pressure cavity are both connected with the pressure difference transmitter, one end of the bluff body is connected with a power divider, and the power divider is further connected with a microwave signal source; the high-pressure cavity is arranged on the incident flow surface of the bluff body, and the incident flow surface is the front side surface of the bluff body; the low-pressure cavity is arranged on the back flow surface of the bluff body; and the back flow surface is the rear side surface of the bluff body. The gas content and the water content of the oil-gas-water three-phase mass flow can be measured while the oil-gas-water three-phase mass flow is accurately calculated, the manufacturing cost of the measuring device is reduced, and the structure of the device is optimized.

Description

Technical Field

[0001] The present invention relates to the technical field of three-phase flow detection, and in particular to an oil, gas and water three-phase flow measurement device and method based on an average-velocity tube vortex street and a microwave antenna. Background Art

[0002] In many fields such as the petroleum industry, accurate measurement of water content in three-phase flow (gas, oil, water) is crucial. For example, in oil production, water content information plays a key role in evaluating reservoir production conditions, optimizing production processes, and judging oil well production efficiency.

[0003] At present, the traditional differential pressure measurement method is to use a pressure pipe to introduce high pressure and low pressure into the transmitter. The differential pressure sensor adopts an integrated structure of high and low pressure chambers, and places a measuring diaphragm between high and low pressure. When the pressures generated by the two pressure chambers are different, the pressure diaphragm will be deformed, converted into electrical signals for output, and the differential pressure value will be indirectly calculated. In order to change the pressure value in the pressure chamber, it is necessary to use a pressure pipe to induce pressure on the measuring pipeline and introduce two different pressure values ​​into the pressure chamber. As an emerging measurement method, microwave antenna technology has gradually become a research hotspot in the field of three-phase moisture content measurement with its unique advantages.

[0004] Traditional differential pressure measurement requires the introduction of high pressure and low pressure into a sensing unit. Due to the resistance effect, the piezoelectric effect is relatively mature and is affected by the two differential pressures. This can make the measurement more accurate and more sensitive during the measurement process. However, its disadvantage is also obvious, that is, it is greatly affected by the pressure-inducing pipe. When the fluid is full of multiphase flow, the pressure in the pressure-inducing pipe will be greatly affected by the medium in the pipe, especially when measuring vertical pipes. In addition, the parameters of the installed pressure chamber are relatively complex, and it is impossible to ensure that the parameters of the two pressure chambers are completely consistent, which will cause errors in the measurement process.

[0005] The technology of measuring three-phase water content by traditional microwave antenna is based on the difference in microwave dielectric properties. It quantitatively characterizes the water content of the oil, gas and water three-phase flow pair by emitting electromagnetic waves of specific frequencies and analyzing the reflection / transmission signal intensity, phase or spectrum characteristics. It has been widely used in the fields of oil extraction, chemical pipelines, etc. The mainstream technologies include frequency domain reflection method and time domain reflection method. The commonly used frequencies are concentrated in the range of 1-10GHz. The low-frequency band has a higher penetration depth and is suitable for long-distance pipelines, while the high-frequency band has better resolution, but is easily interfered by the conductive layer of the pipe wall. The traditional system adopts a single antenna or dipole array design, and realizes the conversion by establishing a calibration model of dielectric constant and water content. However, under complex multiphase flow conditions, it still faces the problems of severe signal attenuation, measurement errors caused by uneven fluid distribution, and model drift under the action of temperature and pressure coupling. Summary of the invention

[0006] The object of the present invention is to provide an oil-gas-water three-phase flow measurement device and method based on a pitot tube vortex street and a microwave antenna, which can accurately calculate the mass flow rates of the oil-gas-water three phases, measure the gas holdup and water cut, reduce the manufacturing cost of the measurement device, and optimize the structure of the measurement device.

[0007] To achieve the above object, the present invention provides the following solutions:

[0008] An oil-gas-water three-phase flow measurement device based on a pitot tube vortex street and a microwave antenna, comprising: a bluff body, a differential pressure transmitter, a power divider, and a microwave signal source;

[0009] The bluff body is vertically placed at the central position inside the target pipeline, and two cavities are provided inside the bluff body, namely a high-pressure cavity and a low-pressure cavity. Both the high-pressure cavity and the low-pressure cavity are connected to the differential pressure transmitter. One end of the bluff body is connected to the power divider, and the power divider is also connected to a microwave signal source; the high-pressure cavity is arranged on the upstream-facing surface of the bluff body, and the upstream-facing surface is the front side of the bluff body; the low-pressure cavity is arranged on the downstream-facing surface of the bluff body; the downstream-facing surface is the rear side of the bluff body.

[0010] Optionally, the bluff body is the bluff body in a vortex flowmeter, and is cylindrical, and is used as the body of the pitot tube and the antenna for high-frequency microwaves.

[0011] Optionally, both the upper and lower ends of the bluff body are connected to the pipeline wall of the target pipeline, and insulating gaskets are provided between them and the pipeline wall.

[0012] Optionally, a partition parallel to both the upstream-facing surface and the downstream-facing surface is provided at the central position of the bluff body, and the partition is used to divide the cavity of the bluff body into a high-pressure cavity and a low-pressure cavity.

[0013] Optionally, four high-pressure holes and four low-pressure holes are respectively opened on the bluff body; each high-pressure hole is located on the central axis of the upstream-facing surface of the bluff body and is communicated with the high-pressure cavity; each low-pressure hole is located on the central axis of the downstream-facing surface of the bluff body and is communicated with the low-pressure cavity.

[0014] The present invention also provides an oil-gas-water three-phase flow measurement method based on a pitot tube vortex street and a microwave antenna, which is applied to the device as described above, and includes:

[0015] Emitting microwave signals into the pipeline through the insulating bluff body antenna connected to the microwave signal source, collecting the voltages at both ends of the bluff body by using a data acquisition card, and calculating the average differential pressure based on the differences in dielectric constants in the oil-gas-water three-phase flow and the vortex shedding frequency f, and further obtaining the gas holdup α of the oil-gas-water three phasesg , the water cut α of the oil-gas-water three-phase w and the mass flow rate Q of the fluid m ;

[0016] Based on the gas content α of the oil-gas-water three-phase g , the water cut α of the oil-gas-water three-phase w and the mass flow rate Q of the fluid m , calculate the mass flow rate of each phase of the oil-gas-water three-phase flow.

[0017] Optionally, the calculation formula for the gas content α of the oil-gas-water three-phase g is:

[0018]

[0019] In the formula, ρ m is the average density of the gas-liquid two-phase annular mist flow, kg / m 3 ; ρ g is the gas density, kg / m 3 ; ρ w is the liquid density, kg / m 3 .

[0020] Optionally, the calculation formula for the water cut α of the oil-gas-water three-phase w is:

[0021]

[0022] In the formula, A m is the microwave attenuation of the vertical antenna; β is the correction coefficient of the slip velocity ratio obtained by experimental fitting; C is the background noise; k is the sensor sensitivity coefficient; ε m is the equivalent dielectric loss of the mixed medium; X eff is the equivalent Lomax coefficient.

[0023] Optionally, the calculation formula for the mass flow rate of each phase of the oil-gas-water three-phase flow is:

[0024] Q mg = α g Q m

[0025] Q mw = α w Q m

[0026] Q mo = (1 - α g - α w )Q m

[0027] In the formula, α g is the gas content of the oil-gas-water three-phase; Qm is the mass flow rate of the fluid; α w is the water cut of the oil, gas and water three-phase; Q mg is the mass flow rate of the gas phase; Q mw is the mass flow rate of the water phase; Q mo is the mass flow rate of the oil phase.

[0028] According to the specific embodiments provided by the present invention, the following technical effects are disclosed by the present invention:

[0029] The present invention discloses an oil, gas and water three-phase flow measurement device and method based on a uniform velocity tube vortex street and a microwave antenna. The device includes a bluff body, a differential pressure transmitter, a power divider and a microwave signal source. The bluff body is vertically placed at the central position in the target pipeline, and two cavities are arranged inside the bluff body, namely a high-pressure cavity and a low-pressure cavity. Both the high-pressure cavity and the low-pressure cavity are connected to the differential pressure transmitter. One end of the bluff body is connected to the power divider, and the power divider is also connected to a microwave signal source. The high-pressure cavity is arranged on the upstream-facing surface of the bluff body, and the upstream-facing surface is the front side surface of the bluff body. The low-pressure cavity is arranged on the downstream-facing surface of the bluff body. The downstream-facing surface is the rear side surface of the bluff body. The present invention can accurately calculate the mass flow rates of the oil, gas and water three-phase while measuring the gas holdup and water cut, and reduce the manufacturing cost of the measuring device and optimize the device structure. Description of the Drawings

[0030] In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required to be used in the embodiments. Obviously, the drawings in the following description are only some embodiments of the present invention. For those of ordinary skill in the art, other drawings can be obtained based on these drawings without creative efforts.

[0031] Figure 1 is the overall schematic diagram of the oil, gas and water three-phase mass flow measurement device in this embodiment;

[0032] Figure 2 is the disassembly diagram of the oil, gas and water three-phase mass flow measurement device in this embodiment;

[0033] Figure 3 is the mass flow measurement flow chart of the vortex street uniform velocity tube in this embodiment;

[0034] Figure 4 is the structural schematic diagram of the microwave sensor measurement system in this embodiment;

[0035] Figure 5 is the flow chart of the oil, gas and water three-phase flow measurement method in this embodiment. Detailed Embodiments

[0036] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0037] The object of the present invention is to provide an oil-gas-water three-phase flow measurement device and method based on an averaging pitot tube vortex street and a microwave antenna, which can accurately calculate the mass flow rates of the oil-gas-water three phases, measure their gas holdup and water cut, reduce the manufacturing cost of the measurement device, and optimize the structure of the measurement device.

[0038] In order to make the above objects, features, and advantages of the present invention more obvious and understandable, the present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0039] As Figure 1 shown, the present invention provides an oil-gas-water three-phase flow measurement device based on an averaging pitot tube vortex street and a microwave antenna, including: a bluff body, a differential pressure transmitter, a power divider, and a microwave signal source; the bluff body is vertically placed at the central position in the target pipeline, and two cavities are provided inside the bluff body, namely a high-pressure cavity and a low-pressure cavity, both the high-pressure cavity and the low-pressure cavity are connected to the differential pressure transmitter, one end of the bluff body is connected to the power divider, and the power divider is also connected to a microwave signal source; the high-pressure cavity is arranged on the upstream-facing surface of the bluff body, and the upstream-facing surface is the front side surface of the bluff body; the low-pressure cavity is arranged on the downstream-facing surface of the bluff body; the downstream-facing surface is the rear side surface of the bluff body.

[0040] As a specific implementation manner, the above device and the calculation of the application device will be specifically described.

[0041] The object of this embodiment is to provide an oil-gas-water three-phase mass flow measurement device and method using pitot tube velocity measurement, Karman vortex street, and microwave dual-polarization distributed sensing principles to solve the problems of complex measurement process and large measurement error caused by the need to combine multiple flowmeters for measurement in existing combined mass flowmeters.

[0042] In this embodiment, the structure is optimized according to the structures and principles of the averaging pitot tube flowmeter, the vortex flowmeter, and the microwave antenna, and a highly integrated oil-gas-water three-phase flow measurement device combining the averaging pitot tube, the vortex street, and the microwave antenna is designed. Based on the measurement principle of the averaging pitot tube flowmeter, which requires measuring the pressure difference in a specific area, combined with the principle of the vortex flowmeter, when the fluid passes through the bluff body to generate vortices, a differential pressure transmitter is connected between the high-pressure chamber and the low-pressure chamber of the bluff body, and a current signal containing the differential pressure signal and the vortex shedding frequency can be obtained, and then the average value of the vortex shedding frequency f differential pressure can be obtained. Thus, the gas-phase mass flow rate Q in the oil-gas-water three-phase can be calculated. mg Furthermore, the bluff body that generates the vortex street can be used as the structure of the antenna microwave sensor. Through the transmission and reception of its high-frequency microwaves and the analysis of signal attenuation, the measurement of the water-phase mass flow rate Q in the oil-gas-water three-phase can be realized. mw Therefore, the mass flow rates of the three phases can be obtained without separating the oil, gas, and water in advance.

[0043] Therefore, based on theoretical analysis and previous work experience, the structures of the traditional averaging pitot tube flowmeter and the vortex flowmeter are integrated and optimized. Further combined with the high-frequency microwave sensor, the oil-gas-water three-phase flow measurement device and method based on the averaging pitot tube, the vortex street, and the microwave antenna are highlighted. This embodiment is based on the Karman vortex street and the microwave dual-polarization distributed sensing principle. The gas-phase mass flow rate of the oil-gas-water three-phase is obtained through the pressure difference and the vortex shedding frequency. Further, high-frequency microwaves are emitted into the medium, and by using the dielectric characteristic principle of the liquid phase, the received microwave signal is compared and calculated with the starting signal to obtain the water-phase mass flow rate of the oil-gas-water three-phase, and then the mass flow rates of the oil, gas, and water three-phase are obtained. Three signals can be extracted from the two signals of this device for calculation, which has high integration and reliability. This embodiment can extract the differential pressure, the shedding frequency, and the voltage signal reflecting the microwave attenuation degree from the two signals, and the mass flow rate can be obtained through the calculation of the processor. This embodiment has high integration, simple installation, safety and reliability. Compared with other combined flowmeters, it can adapt to more environments. In this way, while accurately calculating the mass flow rates of the oil, gas, and water three-phase, the manufacturing cost of the measurement device can be reduced, the structure of the measurement device can be optimized, and a new method for measuring the mass flow rates of the oil, gas, and water three-phase is provided.

[0044] For this device, the bluff body in the vortex flowmeter is used as the averaging pitot tube body and the antenna of the high-frequency microwave. A cylindrical bluff body is vertically placed at the center position in the pipeline, so that stable vortices can be generated behind the bluff body during the flow of the medium. Two cavities are arranged inside the bluff body, which are divided into a high-pressure chamber and a low-pressure chamber. Further, the high and low pressure chambers of the cavity are connected to the high-frequency differential pressure transmitter. Further, the bluff body is connected to the power divider and the microwave signal source to realize the transmission and reception of high-frequency microwaves.

[0045] The upper and lower ends of the fluid blocker are connected to the pipe wall, and there is an insulating gasket between it and the pipe; the front side of the fluid blocker is the upstream-facing surface, and the rear side of the fluid blocker is the downstream-facing surface; a partition parallel to both the upstream-facing surface and the downstream-facing surface is provided at the central position inside the fluid blocker, and the partition divides the inner cavity of the fluid blocker into a front high-pressure chamber and a rear low-pressure chamber; four high-pressure holes communicating with the high-pressure chamber are successively opened from top to bottom on the central axis of the upstream-facing surface of the fluid blocker, and four low-pressure holes (i.e., fluctuating pressure tapping holes) communicating with the low-pressure chamber are successively opened from top to bottom on the central axis of the downstream-facing surface of the fluid blocker. The high- and low-pressure chambers are connected to a high-frequency differential pressure transmitter; the fluid blocker is connected to a power divider and a microwave signal source; by using an algorithm to calculate, it is realized that only one coupled high-frequency differential pressure signal can be used to obtain the average differential pressure value and two signals of the vortex shedding frequency f extracted therefrom. Further, by using the emission and reception of high-frequency microwaves, microwave signals with different phases before and after are obtained, and according to the calculation of formula (8), the gas holdup and water cut can be obtained, and then the mass flow rates Q mg 、Q mw 、Q mo 。

[0046] Working principle:

[0047] A fluid blocker (also called a vortex generator) is placed in the pipe in a direction perpendicular to the flow direction of the measured medium. When the fluid flows through the fluid blocker, two rows of regularly staggered vortices are alternately separated and released on both sides behind the fluid blocker. When the medium flows through the pipe and enters the high-pressure chamber and the low-pressure chamber, the different pressure signals in the high- and low-pressure cavities are collected by the high-frequency differential pressure transmitter above, and the output signal is a 4-20 mA current signal. The current signal is connected to a resistor with R1 = 250 Ω, and the voltage across R1 is collected by a data acquisition card. Through the decoupling and calculation of the algorithm, the average differential pressure value and the vortex shedding frequency f can be obtained, and then the gas holdup α of the oil-gas-water three-phase can be obtained g 。

[0048] The high-frequency microwave technology is based on the 24 GHz microwave dual-polarization distributed sensing principle. Microwave signals are transmitted into the pipe through an insulating fluid blocker antenna connected to a microwave signal source. By using the difference in dielectric constants among the oil-gas-water three-phase flow, where the dielectric losses of oil (non-polar) and gas (non-polar) to microwaves are much smaller than that of water (polar), further, the change in the signal attenuation characteristics is caused to realize the detection of the water cut α w At the same time, the Doppler effect is used to analyze the phase shift to obtain the flow velocity and flow pattern information: water cut α wQuantitatively characterized by the attenuation coefficient, the flow rate is correlated with the phase shift and Doppler frequency shift; the hardware system uses an ADF4351 microwave signal source to drive a power splitter to distribute a 24 GHz signal to the insulating obstruction flow body antenna. After low-noise amplification at the receiving end, it is frequency-converted to the intermediate frequency, and finally the moisture content α is fused through a multi-physical field inversion model w 。

[0049] The formulas for calculating the mass flow rates of oil, gas, and water phases using an averaging pitot tube flowmeter and a vortex flowmeter are as follows:

[0050]

[0051] Where, Q m is the mass flow rate of the oil, gas, and water phases measured by the novel averaging pitot tube in the present invention, kg / s; ρ m is the average density of the mass flow rate of the oil, gas, and water phases flowing through the novel averaging pitot tube; kg / m 3 ; f is the vortex frequency collected by the novel averaging pitot tube, Hz; ε is the expansion coefficient of the measured medium in the novel averaging pitot tube. For compressible fluids such as gases and vapors, ε < 1; ε can be obtained by looking up the table; is the average differential pressure between the total pressure chamber and the static pressure chamber in the flow obstruction body, Pa; K1 is the instrument coefficient of the vortex flowmeter after compensation and correction; K2 is the flow coefficient of the averaging pitot tube flowmeter after correction; among them, the values of K1 and K2 need to be calibrated during the experiment.

[0052] The calculation formula for the mass flow rate Q of the oil, gas, and water phases m and the frequency f is as follows:

[0053]

[0054] The average density of the oil, gas, and water phases is obtained from Equation (3):

[0055]

[0056] The mass flow rate of the oil, gas, and water phases is obtained from Equation (4) and Equation (5):

[0057]

[0058] K m =K1K2 2 ε 2 (7)

[0059] The mass flow rate of the oil, gas, and water phases is obtained from Equation (6) and Equation (7):

[0060]

[0061] The gas holdup of the mass flow rate of the oil, gas, and water phases is:

[0062]

[0063] In the formula, α g is the mass gas holdup of the mass flow rates of oil, gas and water phases.

[0064]

[0065] In the formula, A is the cross-sectional area of the pipeline; K m is the mass flowmeter coefficient, which is a physical quantity related to the shape and size of the vortex generator, and the value of K m can be obtained through experimental measurement and calibration; ρ g is the gas density, kg / m 3 ; ρ w is the liquid density, kg / m 3 ; ρ m is the average density of the annular mist flow of the gas-liquid two-phase, kg / m 3 . Then the vortex shedding frequency f and the average differential pressure are obtained. According to Equation (8), the mass flow rate Q of the fluid is further calculated. m .

[0066] When the microwave signal source receives the corresponding configuration instruction from the master controller, it outputs a single frequency to the power divider at the specified frequency point; the power divider divides the microwave input signal into two groups of signals with equal outputs. One group of signals drives the microwave antenna to sense the medium, and the other group enters the amplitude and phase discriminator as the original reference signal; the amplitude and phase discriminator obtains the signal after attenuation at the output end of the antenna, discriminates it with the original reference signal, compares the attenuation amount, and outputs the amplitude attenuation value, which is the microwave attenuation A of the vertical antenna. m .

[0067] Among them, the microwave attenuation A of the vertical antenna m is proportional to the equivalent dielectric loss ε m of the mixed medium:

[0068] A m = kε m + C (11)

[0069] In the formula, k is the sensor sensitivity coefficient, and C is the background noise (attenuation of the empty pipe).

[0070] In the three-phase flow, the equivalent dielectric loss ε m can be approximately the weighted sum of the volume fractions of each phase:

[0071] ε m = α w · ε w + (1 - α w ) · (α g · ε g + (1 - α g - αw )·ε o ) (12)

[0072] Wherein, α w and α g are the water content and gas content respectively; ε w and ε g and ε o are the imaginary parts of the dielectric losses of water, gas and oil (water dominates, ε w >> ε g ≈ ε o ≈ 0).

[0073] Furthermore:

[0074] A m = k·α w ·ε w + C (13)

[0075] In the three-phase flow, it needs to be extended to the equivalent parameters of the oil-gas-water three-phase flow. Assuming that oil and gas are combined into a non-aqueous phase, the equivalent Lomakin coefficient is:

[0076]

[0077] Furthermore:

[0078]

[0079] Wherein, β is the correction coefficient of the slip velocity ratio obtained by experimental fitting; therefore, the mass flow rates of each phase in the oil-gas-water three-phase flow are:

[0080] Q mg = α g Q m (16)

[0081] Q mw = α w Q m (17)

[0082] Q mo = (1 - α g - α w )Q m (18)

[0083] As a specific embodiment, a specific application process as shown in Figures 2 - 5 is provided.

[0084] Figure 2It is a disassembly diagram of an oil-gas-water three-phase mass flow measuring device. The cylindrical bluff body is connected to the head of the screw. There are four pressure tapping holes on each of the left and right sides of the bluff body. The pressure tapping holes on the left side are the high-pressure hole 1, high-pressure hole 2, high-pressure hole 3, and high-pressure hole 4 from top to bottom in sequence. The pressure tapping holes on the right side are the low-pressure hole 1, low-pressure hole 2, low-pressure hole 3, and low-pressure hole 4 from top to bottom in sequence. The high-pressure hole 1 and the low-pressure hole 1 are located at 0.8880R in the radial direction. The high-pressure hole 2 and the low-pressure hole 2 are located at 0.4596R in the radial direction. The high-pressure hole 4 and the high-pressure hole 3 are symmetric about the center of the left cross-section of the bluff body respectively. The low-pressure hole 4 and the low-pressure hole 3 are symmetric about the center of the left cross-section of the bluff body with respect to the low-pressure hole 1 and the low-pressure hole 2 respectively. A high-pressure chamber and a low-pressure chamber are opened in the bluff body, and both are cylindrical. The two pressure chambers are respectively connected to both ends of a single-crystal silicon high-frequency differential pressure transmitter. To ensure the accuracy of measurement, the geometric dimensions and materials of the high- and low-pressure chambers are kept consistent. The geometric dimensions of the pressure chambers are measured with a laser length measuring instrument to ensure that the geometric dimensions of the two pressure chambers are the same, reducing the error of pressure measurement. The ratio of the width of the upstream face of the bluff body to the inner diameter of the pipeline is 0.28, avoiding the influence of too large width of the upstream face of the bluff body on the flow area and too small width on the generation of vortices. Further, the terminals at both ends of the bluff body are respectively connected to a data processor such as the transmitting and receiving ends of a microwave antenna.

[0085] As Figure 3 shown, connect the positive pole of the single-crystal silicon high-frequency differential pressure transmitter to a 24V DC voltage source, and the output signal is a current signal of 4 - 20mA. Connect the current signal to a resistor with R1 = 250Ω, and use a data acquisition card to collect the voltage across R1. Through the decoupling and calculation of the algorithm, the average differential pressure and the vortex shedding frequency f can be obtained, and then the gas holdup α of the oil-gas-water three-phase can be calculated. g .

[0086] The process of transmitting and receiving high-frequency microwave signals mainly includes: when the transmitted microwave passes through the oil-gas-water three-phase flow in the pipeline, water and oil molecules absorb the microwave energy and convert it into heat energy, resulting in the attenuation of the signal amplitude; the antenna at the receiving end (shared with the transmitting end) captures the weak microwave signal after passing through the gas-liquid mixture and transmits it to the amplitude and phase discriminator through a coaxial cable; compare the amplitude and phase differences between the transmitted signal (reference signal) and the received signal, and output a voltage signal reflecting the degree of microwave attenuation; convert the analog voltage signal of the amplitude and phase discriminator into a digital signal for the main controller to read and process, and then obtain the water cut α of the oil-gas-water three-phase flow. w . As Figure 4 shown is a schematic diagram of the microwave sensor measurement system.

[0087] Furthermore, after obtaining the corresponding data in the above experiment, the mass flow rate Q of the oil-gas-water three-phase flow m , the gas holdup α g , and the water cut α wCalculate the mass flow rates of the oil, gas, and water phases respectively. As Figure 5 It is a flowchart of the method for measuring the flow rates of the oil, gas, and water phases.

[0088] As another embodiment, the device for measuring the mass flow rates of the oil, gas, and water phases includes a single-crystal silicon high-frequency differential pressure transmitter, a flow obstruction body, a high-pressure pressure tapping hole, a low-pressure pressure tapping hole, an insulating gasket, a microwave main controller, a power divider, a microwave signal source, an amplitude and phase discriminator, etc.

[0089] A flow obstruction body is arranged on the circumferential line of the pipeline center, and the flow obstruction body is designed to be cylindrical. There are two vertical pressure tapping cavities penetrating through the inside of the flow obstruction body, namely a high-pressure pressure tapping cavity and a low-pressure pressure tapping cavity, and four pairs of pressure tapping holes are arranged on the upstream and downstream surfaces where the medium passes according to the equal ring area method. The upstream surface from top to bottom is high-pressure hole 1, high-pressure hole 2, high-pressure hole 3, and high-pressure hole 4. High-pressure hole 1 and high-pressure hole 2 are respectively located at 0.8880R and 0.4596R in the radial direction. High-pressure hole 4 and high-pressure hole 1 are symmetric about the center of the left cross-section of the flow obstruction body, and the same applies to high-pressure hole 3 and high-pressure hole 2. The pressure tapping holes on the downstream surface are low-pressure hole 1, low-pressure hole 2, low-pressure hole 3, and low-pressure hole 4 accordingly. Further, the upper and lower ends of the flow obstruction body are connected to the microwave main controller through terminals, achieving the effect of using the cylindrical flow obstruction body as a microwave antenna. Furthermore, by extracting and calculating the data obtained from the differential pressure transmitter and the microwave main controller, the mass flow rates Q of the oil, gas, and water phases can be obtained m , as well as the gas holdup α g and the water cut α w . Further calculations can be performed to obtain the mass flow rates of the oil, gas, and water phases respectively, and the results are displayed on the output module.

[0090] In summary, it can be seen from this embodiment that: to meet the objective requirements of cost reduction, efficiency improvement, and safe production at the production site, a device and method for measuring the flow rates of the oil, gas, and water phases based on a uniform velocity tube vortex street and a microwave antenna are selected. Using the measurement principles of the uniform velocity tube vortex street and high-frequency microwaves, a high degree of integration of the measurement instrument structure is achieved, and the average differential pressure can be extracted from the two signals The shedding frequency and the voltage signal reflecting the degree of microwave attenuation can be obtained. Through calculation by the processor, the mass flow rate can be obtained. It solves the problems of complex installation and high measurement error of most combined flowmeters. And the measurement of the oil, gas, and liquid three-phase flow can be carried out on-site, reducing the additional error and calibration cost during the disassembly and transportation processes, facilitating the staff to quickly complete the task of calibrating a large number of instruments, and ensuring the improvement of accuracy and reliability while meeting the high degree of integration in structure.

[0091] In this specification, each embodiment is described in a progressive manner. The key point of each embodiment is to illustrate the differences from other embodiments. The same or similar parts among the embodiments can be referred to each other.

[0092] In this article, specific examples are used to elaborate on the principles and implementation manners of the present invention. The description of the above embodiments is only used to help understand the core idea of the present invention. At the same time, for those of ordinary skill in the art, according to the idea of the present invention, there will be changes in the specific implementation manners and application scopes. To sum up, the content of this specification should not be construed as a limitation on the present invention.

Claims

1. An oil-gas-water three-phase flow measurement device based on a Pitot tube vortex street and a microwave antenna, characterized in that Comprising: A fluid blocker, a differential pressure transmitter, a power divider, and a microwave signal source; The fluid blocker is vertically placed at the central position inside the target pipeline, and two cavities are arranged inside the fluid blocker, namely a high-pressure cavity and a low-pressure cavity. The high-pressure cavity and the low-pressure cavity are both connected to the differential pressure transmitter. One end of the fluid blocker is connected to the power divider, and the power divider is also connected to a microwave signal source. The high-pressure cavity is arranged on the flow-facing surface of the fluid blocker, and the flow-facing surface is the front side surface of the fluid blocker. The low-pressure cavity is arranged on the flow-back surface of the fluid blocker. The flow-back surface is the rear side surface of the fluid blocker.

2. The oil-gas-water three-phase flow measurement device based on an averaging pitot tube vortex street and a microwave antenna according to claim 1, wherein The fluid blocker is the fluid blocker in a vortex flowmeter, and is cylindrical, and is used as the body of a pitot tube and an antenna for high-frequency microwaves.

3. The oil-gas-water three-phase flow measurement device based on an averaging pitot tube vortex street and a microwave antenna according to claim 1, wherein Both the upper and lower ends of the fluid blocker are connected to the pipeline wall of the target pipeline, and insulating gaskets are arranged between the fluid blocker and the pipeline wall.

4. The oil-gas-water three-phase flow measurement device based on a pitot tube vortex street and a microwave antenna according to claim 1, wherein A partition parallel to both the flow-facing surface and the flow-back surface is arranged at the central position of the fluid blocker, and the partition is used for dividing the cavity of the fluid blocker into a high-pressure cavity and a low-pressure cavity.

5. The oil-gas-water three-phase flow measurement device based on an averaging pitot tube vortex street and a microwave antenna according to claim 1, characterized in that Four high-pressure holes and four low-pressure holes are respectively formed in the fluid blocker; each of the high-pressure holes is located on the central axis of the flow-facing surface of the fluid blocker and is communicated with the high-pressure cavity; each of the low-pressure holes is located on the central axis of the flow-back surface of the fluid blocker and is communicated with the low-pressure cavity.

6. A method for measuring the oil-gas-water three-phase flow rate based on a uniform velocity tube vortex street and a microwave antenna, which is applied to the device according to any one of claims 1-5, and is characterized in that, Comprising: A microwave signal is transmitted into the pipeline through an insulating bluff-body antenna connected to a microwave signal source. The voltage across the bluff body is collected by a data acquisition card, and based on the difference in dielectric constants in the oil-gas-water three-phase flow, the average differential pressure ΔP and the vortex shedding frequency f are calculated, and then the gas holdup α of the oil-gas-water three-phase flow, g the water cut α of the oil-gas-water three-phase flow w and the mass flow rate Q of the fluid m ; Gas holdup α based on oil-gas-water three-phase g 、Water cut α of oil-gas-water three-phase w And mass flow rate Q of fluid m To calculate the mass flow rate of each phase in oil-gas-water three-phase flow 7. The oil-gas-water three-phase flow measurement method based on the averaging pitot tube vortex street and the microwave antenna according to claim 6, wherein The gas holdup α of the oil-gas-water three-phase g is calculated by the formula: where ρ m is the average density of the gas-liquid two-phase annular mist flow, kg / m 3 ; ρ g is the gas density, kg / m 3 ; ρ w is the liquid density, kg / m 3 .

8. The oil-gas-water three-phase flow measurement method based on an averaging pitot tube vortex street and a microwave antenna according to claim 6, characterized in that The water cut α of the oil-gas-water three-phase w is calculated by the formula: where A m is the microwave attenuation of the vertical antenna; β is the slip speed ratio correction coefficient fitted by experiment; C is the background noise; k is the sensor sensitivity coefficient; ε m is the equivalent dielectric loss of the mixed medium; X eff is the equivalent Romer coefficient.

9. The oil-gas-water three-phase flow measurement method based on an averaging pitot tube vortex street and a microwave antenna according to claim 6, characterized in that, The calculation formula for the mass flow rate of each phase of the oil-gas-water three-phase flow is: Q mg = α g Q m Q mw = α w Q m Q mo = (1 - α g - α w )Q m where α g is the gas holdup of the oil-gas-water three-phase; Q m is the mass flow rate of the fluid; α w is the water cut of the oil-gas-water three-phase; Q mg is the gas-phase mass flow rate; Q mw is the water-phase mass flow rate; Q mo is the oil-phase mass flow rate.

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