Differential pressure type supercritical carbon dioxide flowmeter and flow measuring method thereof

Abstract

The invention relates to a differential pressure type supercritical carbon dioxide flow meter and a flow measuring method thereof.The flow meter comprises a throttling body, the throttling body comprises a connecting pipe body, a throttling plate perpendicular to the axis of the connecting pipe body is installed in the connecting pipe body, a throttling hole coaxial with the connecting pipe body is formed in the throttling plate, and the throttling hole is communicated with the connecting pipe body; a mounting part is arranged on the outer wall of the connecting pipe body; the upstream pipe body and the downstream pipe body are coaxially and hermetically arranged in the connecting pipe body in a penetrating manner, and are respectively positioned at the upstream and the downstream of the throttling plate; an inner cavity of the upstream pipe body and an inner cavity of the downstream pipe body form a flow channel for circulating supercritical carbon dioxide; and the pressure difference detection piece is arranged on the mounting part and is used for monitoring the difference value between the upstream pressure of the throttle plate and the downstream pressure of the throttle plate. The flow meter can measure the supercritical carbon dioxide flow at a specific underground layer in real time, and provides accurate reference data for oilfield development engineering.

Description

Technical Field

[0001] The invention relates to a differential pressure supercritical carbon dioxide flowmeter and a flow measurement method thereof, belonging to the technical field of medium flow measurement. Background Art

[0002] Supercritical carbon dioxide has the advantages of wide sources and low transportation costs. Its physical properties include density close to that of water, viscosity close to that of air, low interfacial tension after mixing, and good fluidity. It is an effective oil displacement agent and is widely studied and applied in oilfield development projects.

[0003] Downhole injection of supercritical carbon dioxide is a major application direction for supplementing formation pressure deficit and increasing oil production. Specifically, liquid carbon dioxide is pumped into the wellbore on the ground to form high pressure (30MPa~50MPa), high temperature (40℃~150℃), large flow (5,000Nm 3 / d~200,000Nm 3 / d) of supercritical carbon dioxide, which enters the formation to achieve the purpose of replenishing formation pressure and increasing oil production. In the prior art, the total mass of carbon dioxide injected into the formation can be calculated by measuring the mass difference before and after the injection of liquid carbon dioxide on the ground.

[0004] Due to the heterogeneity of the reservoir, supercritical carbon dioxide needs to be injected in layers. When there are multiple injection layers in the well at the same time, the current general ground measurement technology cannot measure the amount of carbon dioxide injected in a single specific layer underground. Summary of the invention

[0005] In view of the above technical problems, the present invention provides a differential pressure supercritical carbon dioxide flowmeter and a flow measurement method thereof, which can measure the supercritical carbon dioxide flow at a specific layer downhole in real time and provide accurate reference data for oilfield development projects.

[0006] To achieve the above object, the present invention adopts the following technical solutions: A differential pressure supercritical carbon dioxide flowmeter, comprising: A throttling body, the throttling body comprising a connecting tube body, a throttling plate perpendicular to the axis of the connecting tube body being installed on the connecting tube body, a throttling hole coaxial with the connecting tube body being opened on the throttling plate, and a mounting portion being arranged on the outer wall of the connecting tube body; The upstream pipe body and the downstream pipe body are coaxially and sealedly disposed in the connecting pipe body and are respectively located upstream and downstream of the throttle plate; the inner cavity of the upstream pipe body and the inner cavity of the downstream pipe body form a flow channel for circulating supercritical carbon dioxide; The pressure difference detection component is arranged on the mounting portion and is used to monitor the difference between the pressure upstream of the throttle plate and the pressure downstream of the throttle plate.

[0007] The differential pressure supercritical carbon dioxide flowmeter is preferably provided with an upstream pressure-bearing chamber and a downstream pressure-bearing chamber on the mounting portion, the differential pressure detecting element is located between the upstream pressure-bearing chamber and the downstream pressure-bearing chamber, the upstream pressure-bearing chamber is connected with the upstream end of the differential pressure detecting element, and is connected with the upstream tube body through the upstream pressure taking port; the downstream pressure-bearing chamber is connected with the downstream end of the differential pressure detecting element, and is connected with the downstream tube body through the downstream pressure taking port.

[0008] In the differential pressure supercritical carbon dioxide flowmeter, preferably, the upstream pipe body is tightly connected to the connecting pipe body, and a first sealing member is provided between the upstream pipe body and the connecting pipe body; and / or, The downstream pipe body is tightly connected to the connecting pipe body, and a second sealing member is disposed in the downstream pipe body and the connecting pipe body.

[0009] The differential pressure supercritical carbon dioxide flowmeter preferably also includes a temperature detection component and a pressure detection component, both of which are arranged upstream of the throttle plate, the temperature detection component is used to monitor the temperature of the supercritical carbon dioxide in real time, and the pressure detection component is used to monitor the pressure of the supercritical carbon dioxide in real time.

[0010] In the differential pressure supercritical carbon dioxide flowmeter, preferably, the upstream pressure-bearing chamber is communicated with the measuring end of the pressure detection member.

[0011] A second aspect of the present invention provides a method for measuring the flow rate of supercritical carbon dioxide using a differential pressure type, using any one of the differential pressure type supercritical carbon dioxide flowmeters described above, comprising the following steps: Obtain the medium density of supercritical carbon dioxide; Obtaining the throttling pressure difference in the flow channel; Calculate the mass flow rate of supercritical carbon dioxide based on the medium density and throttling pressure difference.

[0012] The pressure differential supercritical carbon dioxide flow measurement method, preferably, obtains the medium density of the supercritical carbon dioxide, comprising the following steps: Obtain the real-time temperature and real-time pressure of supercritical carbon dioxide; The medium density of the supercritical carbon dioxide is calculated according to the real-time temperature, the real-time pressure, and the corresponding relationship between the medium density of the supercritical carbon dioxide and the real-time temperature and the real-time pressure.

[0013] In the pressure differential supercritical carbon dioxide flow measurement method, preferably, the mass flow rate of supercritical carbon dioxide is calculated as follows:

[0014] in, Q m is the mass flow rate of supercritical carbon dioxide; C is the outflow coefficient; ε is the fluid expansion coefficient; d is the inner diameter of the throttle hole; β is the ratio of the inner diameter of the flow channel to the inner diameter of the throttle hole; Δ p is the throttling pressure difference; ρ is the medium density.

[0015] The third aspect of the present invention provides a pressure differential supercritical carbon dioxide flow measurement device, comprising: A first processing unit is used to obtain the medium density of supercritical carbon dioxide; A second processing unit, used for obtaining a throttling pressure difference in the flow channel; The third processing unit is used to obtain the mass flow rate of supercritical carbon dioxide according to the medium density and the throttling pressure difference.

[0016] A fourth aspect of the present invention is a computer-readable storage medium having a computer program stored thereon, wherein the computer program, when executed by a processor, implements the steps of any one of the above-mentioned pressure differential supercritical carbon dioxide flow measurement methods.

[0017] A fifth aspect of the present invention is a computer device, comprising a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein the processor implements the steps of any one of the above-mentioned pressure differential supercritical carbon dioxide flow measurement methods when executing the computer program.

[0018] The present invention adopts the above technical solution, which has the following advantages: The differential pressure supercritical carbon dioxide flow measurement method and flowmeter provided by the present invention, when the fluid medium flows through the throttling part, the flow velocity increases and the static pressure decreases due to local contraction, thereby forming a differential pressure. This differential pressure has a certain relationship with the flow velocity. By detecting the size of the differential pressure, the flow rate of the fluid medium can be measured. Based on this principle, a throttling plate with a throttling hole is set in the flow channel where the supercritical carbon dioxide is located, and the difference between the pressure upstream of the throttling plate and the pressure downstream of the throttling plate (throttling differential pressure) is obtained. The mass flow rate of the supercritical carbon dioxide can be obtained by the obtained throttling differential pressure and the medium density of the supercritical carbon dioxide. The flowmeter is set at different depths in the well. Through the above-mentioned differential pressure supercritical carbon dioxide flow measurement method, the mass flow rate of supercritical carbon dioxide at a specific layer in the well can be measured in real time, providing accurate reference data for oilfield development projects. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 A flow chart of a differential pressure supercritical carbon dioxide flow measurement method provided by an embodiment of the present invention; Figure 2 A schematic diagram of a differential pressure supercritical carbon dioxide flowmeter provided in this embodiment of the present invention; Figure 3 A schematic diagram of the communication connection between the various components in the flow meter provided in this embodiment of the present invention; The reference numerals are as follows: 1-throttling body; 2-upstream pipe body; 3-downstream pipe body; 4-pressure difference detection element; 5-temperature detection element; 6-pressure detection element; 7-first sealing element; 8-second sealing element; 11-connecting pipe body; 12-throttle plate; 13-installation part; 14-upstream pressure port; 15-downstream pressure port; 121-throttle hole; 131 - upstream pressure-bearing chamber; 132 - downstream pressure-bearing chamber. DETAILED DESCRIPTION

[0020] In order to make the purpose, technical solution and advantages of the present invention clearer, the technical solution of the present invention is described clearly and completely below. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary persons in the art without creative work are within the scope of protection of the present invention.

[0021] Unless otherwise defined, the technical or scientific terms used in the present invention shall have the usual meanings understood by persons with ordinary skills in the field to which the present invention belongs. The words "first", "second", "third", "fourth" and similar terms used in the present invention do not indicate any order, quantity or importance, but are only used to distinguish different components. Words such as "include" or "comprise" and the like mean that the elements or objects appearing before the word include the elements or objects listed after the word and their equivalents, without excluding other elements or objects. Words such as "connect" or "connected" and the like are not limited to physical or mechanical connections, but may include electrical connections, whether direct or indirect.

[0022] For ease of description, spatially relative terms may be used herein to describe the relationship of one element or feature relative to another element or feature as shown in the figures, such as "inside", "outside", "inner side", "outer side", "below", "above", etc. Such spatially relative terms are intended to include different orientations of the device in use or operation in addition to the orientation depicted in the figures.

[0023] In the prior art, the total mass of carbon dioxide injected into the formation can be calculated by measuring the mass difference before and after the injection of liquid carbon dioxide on the ground. Due to the heterogeneity of the reservoir, supercritical carbon dioxide needs to be injected in layers. When there are multiple injection layers in the well at the same time, the current general ground measurement technology cannot measure the amount of carbon dioxide injected into a single specific layer in the well.

[0024] Based on the above technical problems, the present invention provides a differential pressure supercritical carbon dioxide flowmeter and a flow measurement method thereof, which can measure the supercritical carbon dioxide flow at a specific layer downhole in real time and provide accurate reference data for oilfield development projects.

[0025] like Figure 2 , Figure 3 As shown, the differential pressure supercritical carbon dioxide flowmeter provided by the present invention comprises the following components: the flowmeter comprises a throttling body 1, an upstream tube body 2, a downstream tube body 3 and a differential pressure detection element 4. Among them, the throttling body 1 comprises a connecting tube body 11, a throttling plate 12 and a mounting portion 13, the throttling plate 12 is arranged in the connecting tube body 11, the throttling plate 12 is provided with a throttling hole 121 coaxial with the connecting tube body 11, and the mounting portion 13 is arranged outside the connecting tube body 11; the upstream tube body 2 is coaxially and sealedly penetrated in the connecting tube body 11, and is located upstream of the throttling plate 12; the downstream tube body 3 is coaxially and sealedly penetrated in the connecting tube body 11, and is located downstream of the throttling plate 12; the inner cavity of the upstream tube body 2 and the inner cavity of the downstream tube body 3 form a flow channel for circulating supercritical carbon dioxide. The inner diameter of the upstream tube body 2 is equal to the inner diameter of the downstream tube body 3, and the inner diameter of the upstream tube body 2 and the inner diameter of the downstream tube body 3 are the inner diameters of the above-mentioned flow channel. The pressure difference detection element 4 is arranged on the mounting portion 13, and is used to monitor the difference between the pressure upstream of the throttle plate 12 and the pressure downstream of the throttle plate 12, that is, to monitor the above-mentioned throttling pressure difference Δp.

[0026] like Figure 3 As shown, the flow meter also includes a temperature detection member 5 and a pressure detection member 6, both of which are arranged upstream of the throttle plate 12, and the temperature detection member 5 is used to monitor the temperature of the supercritical carbon dioxide in real time, and the pressure detection member 6 is used to monitor the pressure of the supercritical carbon dioxide in real time. Thus, the real-time temperature and implementation pressure of the supercritical carbon dioxide are obtained, and according to the real-time temperature, implementation pressure, and the corresponding relationship between the medium density of the supercritical carbon dioxide and the real-time temperature and real-time pressure analyzed by the PVTsim software simulation, the real-time temperature and implementation pressure are substituted into the corresponding relationship, thereby obtaining the medium density of the supercritical carbon dioxide. Further, the temperature detection member 5 includes a temperature sensor, and the pressure detection member 6 includes a pressure sensor.

[0027] Continue reading Figure 3, the temperature detection element 5, the pressure detection element 6, and the pressure difference detection element 4 are all connected to the amplifier and the analog-to-digital converter to complete the amplification and conversion of the signal; the amplifier and the analog-to-digital converter are connected to the processor to enable the processor to obtain the real-time pressure, real-time temperature and real-time throttling pressure difference signals. When executing the program, the processor is used to implement the above-mentioned pressure difference supercritical carbon dioxide flow measurement method, and obtain the supercritical carbon dioxide mass flow, and then transmit the mass flow data to the upper computer on the ground through the communication interface. The communication interface is exemplified by RS485.

[0028] like Figure 2 As shown, the installation part 13 is provided with an upstream pressure-bearing chamber 131 and a downstream pressure-bearing chamber 132, and the pressure difference detection member 4 is embedded in the installation part 13 and is located between the upstream pressure-bearing chamber 131 and the downstream pressure-bearing chamber 132. The upstream pressure-bearing chamber 131 is connected to the upstream end of the pressure difference detection member 4 and is connected to the upstream pipe body 2 through the upstream pressure-taking port 14; the downstream pressure-bearing chamber 132 is connected to the downstream end of the pressure difference detection member 4 and is connected to the downstream pipe body 3 through the downstream pressure-taking port 15, so that the pressure difference detection member 4 can obtain the throttling pressure difference. Exemplarily, the pressure difference detection member 4 includes a pressure difference sensor.

[0029] Continue to see Figure 2 The pressure detection component 6 is embedded in the mounting portion 13 to ensure a stable installation, and the upstream pressure-bearing chamber 131 is connected to the measuring end of the pressure detection component 6 so that the pressure detection component 6 can monitor the pressure upstream of the throttle plate 12.

[0030] Furthermore, the pressure detection component 6 is threadedly connected in the mounting portion 13 , and is sealed with the mounting portion 13 via a sealing ring.

[0031] The upstream pipe body 2 and the downstream pipe body 3 are mainly metal sealed, and rubber sealed as an auxiliary, which prolongs the sealing time of the flowmeter under high pressure and high temperature underground for several years. Specifically, the upstream pipe body 2 is threadedly connected to the connecting pipe body 11, and a first seal 7 is provided between the upstream pipe body 2 and the connecting pipe body 11. The downstream pipe body 3 is threadedly connected to the connecting pipe body 11, and a second seal 8 is provided in the downstream pipe body 3 and the connecting pipe body 11. The first seal 7 and the second seal 8 are both rubber rings.

[0032] In this embodiment, the throttle body 1 is an integrated structure, that is, the entire throttle body 1 is an integrally processed part, without the risk of upstream and downstream cross-flow of the throttle hole 121, and is convenient for installation in limited space underground.

[0033] The flow meter provided in this embodiment meets the following requirements: high pressure bearing, the maximum pressure bearing reaches 100Mpa; high flow rate, the maximum flow rate is 200,000Nm 3 / d; High temperature resistance, temperature resistance up to 150℃; Special materials, resistant to CO 2Acid corrosion, high-speed fluid erosion resistance; does not hinder the flow of the medium, and the flow meter measuring components are not corroded by the medium. The flow meter can meet the requirements of supercritical CO2 in the underground high temperature environment of 100MPa and 150℃ 2 Measurement of fluid flow. The flow meter is installed at different layers underground to measure the supercritical carbon dioxide flow passing through the layer in real time and transmit it to the ground. All underground circuit components are made of high-temperature resistant components to ensure that they can work at an ambient temperature of 150°C. The circuit board and transmission lines are shielded by the casing to ensure normal operation under 1000 atmospheres of pressure. All signal lines are transmitted using shielded wires to shield underground electromagnetic interference. The signal processing algorithm executed by the processor uses a digital filter and adopts a variety of filtering algorithms: anti-pulse interference sliding average filtering method, 50Hz notch filter, FIR function filtering, etc., to filter noise signals and ensure measurement accuracy.

[0034] like Figure 1 As shown, this embodiment provides a pressure differential supercritical carbon dioxide flow measurement method, a throttle plate is provided in the flow channel where the supercritical carbon dioxide is located, the throttle plate is provided with a throttle hole, and the inner diameter of the throttle hole is smaller than the inner diameter of the flow channel where the supercritical carbon dioxide is located. Specifically, the pressure differential supercritical carbon dioxide flow measurement method includes: S1. Obtaining the medium density of supercritical carbon dioxide; S2, obtaining the throttling pressure difference in the flow channel; wherein the throttling pressure difference is the difference between the pressure upstream of the throttling plate and the pressure downstream of the throttling plate; S3. Obtain the mass flow rate of supercritical carbon dioxide according to the medium density and the throttling pressure difference.

[0035] When the fluid medium flows through the throttling device, the local contraction causes the flow velocity to increase and the static pressure to decrease, thereby forming a differential pressure. This pressure difference is related to the flow velocity. By detecting the size of the pressure difference, the flow rate of the fluid medium can be measured. Based on this principle, a throttling plate with a throttling hole is set in the flow channel where the supercritical carbon dioxide is located, and the difference between the pressure upstream of the throttling plate and the pressure downstream of the throttling plate (throttling pressure difference) is obtained. The mass flow rate of supercritical carbon dioxide can be obtained by the obtained throttling pressure difference and the medium density of supercritical carbon dioxide. The flowmeter is set at different depths underground. Through the above-mentioned pressure difference supercritical carbon dioxide flow measurement method, the supercritical carbon dioxide mass flow rate at a specific layer underground can be measured in real time, providing accurate reference data for oilfield development projects.

[0036] In step S1 of this embodiment, obtaining the medium density of supercritical carbon dioxide includes: Obtain the real-time temperature and real-time pressure of supercritical carbon dioxide; The medium density of the supercritical carbon dioxide is obtained according to the real-time temperature, the real-time pressure, and the corresponding relationship between the medium density of the supercritical carbon dioxide and the real-time temperature and the real-time pressure.

[0037] The physical parameters of supercritical carbon dioxide (medium density, medium viscosity, medium static sound velocity, etc.) are affected by pressure and temperature. Therefore, the flow rate of supercritical carbon dioxide cannot be simply calculated based on the sound velocity using the conventional flow calculation formula. Specifically, in this embodiment, the medium density of supercritical carbon dioxide at different pressures and temperatures can be analyzed by PVTsim software simulation, and the corresponding relationship between the medium density of supercritical carbon dioxide and the real-time temperature and real-time pressure can be established. Subsequently, based on the corresponding relationship, the monitored real-time temperature and the implemented pressure, the medium density of supercritical carbon dioxide at the current temperature and current pressure can be obtained.

[0038] Specifically, in step S3, the mass flow rate of supercritical carbon dioxide is calculated as follows:

[0039] in, Q m is the mass flow rate of supercritical carbon dioxide; C is the outflow coefficient; ε is the fluid expansion coefficient; d is the inner diameter of the throttle hole; β is the ratio of the inner diameter of the flow channel to the inner diameter of the throttle hole; Δ p is the throttling pressure difference; ρ is the medium density.

[0040] Outflow coefficient C It indicates the ratio between the actual flow rate of the fluid passing through the throttling device and the theoretical flow rate. It is mainly affected by many factors such as fluid characteristics, pipeline conditions, and the design and installation method of the throttling device. The outflow coefficient of the differential pressure flowmeter is generally between 0.6 and 0.95. The outflow coefficient is mainly affected by the Reynolds number. When the Reynolds number is low, the fluid flow state is laminar, and the outflow coefficient is small at this time; when the Reynolds number is high, the fluid enters a turbulent state, and the outflow coefficient also increases.

[0041] The above outflow coefficient C The calculation formula is:

[0042] in, C is the outflow coefficient; Re D is the Reynolds number of the flow channel, which is a known value; ; .

[0043] The above fluid expansion coefficient εThe calculation formula is:

[0044] Where ε is the fluid expansion coefficient; β is the ratio of the inner diameter of the flow channel to the inner diameter of the throttle hole; p 2 is the pressure downstream of the throttle plate; p 1 The pressure upstream of the throttle plate; it can be understood that p 2 and p 1 The difference is the throttling pressure difference Δ p ; κ is the isentropic index of supercritical carbon dioxide, which is a known value.

[0045] According to the above calculation formula, after obtaining the medium density of supercritical carbon dioxide and the throttling pressure difference, the mass flow rate of supercritical carbon dioxide can be obtained by substituting the two into the calculation formula.

[0046] The third aspect of the present invention provides a pressure differential supercritical carbon dioxide flow measurement device, comprising: A first processing unit is used to obtain the medium density of supercritical carbon dioxide; A second processing unit, used for obtaining a throttling pressure difference in the flow channel; The third processing unit is used to obtain the mass flow rate of supercritical carbon dioxide according to the medium density and the throttling pressure difference.

[0047] A fourth aspect of the present invention is a computer-readable storage medium having a computer program stored thereon, wherein the computer program, when executed by a processor, implements the steps of any one of the above-mentioned pressure differential supercritical carbon dioxide flow measurement methods.

[0048] A fifth aspect of the present invention is a computer device, comprising a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein the processor implements the steps of any one of the above-mentioned pressure differential supercritical carbon dioxide flow measurement methods when executing the computer program.

[0049] The present invention is described in terms of flowcharts and / or block diagrams of methods, devices (systems), and computer program products according to specific embodiments. It should be understood that each process and / or block in the flowchart and / or block diagram, as well as the combination of processes and / or blocks in the flowchart and / or block diagram, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, a special-purpose computer, an embedded processor, or other programmable data processing device to generate a machine, so that the instructions executed by the processor of the computer or other programmable data processing device generate instructions for implementing the processes in the flowchart and / or block diagram. Figure 1 A process or multiple processes and / or boxes Figure 1 A device that provides the functions specified in a block or multiple blocks.

[0050] These computer program instructions may also be stored in a computer-readable memory capable of directing a computer or other programmable data processing device to operate in a specific manner, so that the instructions stored in the computer-readable memory produce an article of manufacture comprising an instruction device, which implements the process Figure 1 A process or multiple processes and / or boxes Figure 1 A function specified in one or more boxes.

[0051] These computer program instructions can also be loaded onto a computer or other programmable data processing device so that a series of operating steps are executed on the computer or other programmable device to produce a computer-implemented process, thereby providing instructions for implementing the process. Figure 1 A process or multiple processes and / or boxes Figure 1 The steps for the functions specified in one or more boxes.

[0052] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A differential pressure supercritical carbon dioxide flowmeter, characterized in that: include: A throttling body (1), the throttling body (1) comprising a connecting tube body (11), a throttling plate (12) perpendicular to the axis of the connecting tube body (11) being installed in the connecting tube body (11), a throttling hole (121) coaxial with the connecting tube body (11) being opened on the throttling plate (12), and a mounting portion (13) being arranged on the outer wall of the connecting tube body (11); The upstream pipe body (2) and the downstream pipe body (3) are coaxially and sealedly disposed in the connecting pipe body (11), and are respectively located upstream and downstream of the throttle plate (12); the inner cavity of the upstream pipe body (2) and the inner cavity of the downstream pipe body (3) form a flow channel for circulating supercritical carbon dioxide; A pressure difference detection element (4) is arranged on the mounting portion (13) and is used to monitor the difference between the pressure upstream of the throttle plate (12) and the pressure downstream of the throttle plate (12).

2. The differential pressure supercritical carbon dioxide flowmeter according to claim 1, characterized in that: An upstream pressure-bearing chamber (131) and a downstream pressure-bearing chamber (132) are provided on the mounting portion (13); the differential pressure detecting element (4) is located between the upstream pressure-bearing chamber (131) and the downstream pressure-bearing chamber (132); the upstream pressure-bearing chamber (131) is connected to the upstream end of the differential pressure detecting element (4), and is connected to the upstream pipe body (2) through an upstream pressure-taking port (14); the downstream pressure-bearing chamber (132) is connected to the downstream end of the differential pressure detecting element (4), and is connected to the downstream pipe body (3) through a downstream pressure-taking port (15).

3. The differential pressure supercritical carbon dioxide flowmeter according to claim 1, characterized in that: The upstream pipe body (2) is tightly connected to the connecting pipe body (11), and a first sealing member (7) is provided between the upstream pipe body (2) and the connecting pipe body (11); and / or, The downstream pipe body (3) is tightly connected to the connecting pipe body (11), and a second sealing member (8) is provided inside the downstream pipe body (3) and the connecting pipe body (11).

4. The differential pressure supercritical carbon dioxide flowmeter according to claim 1, characterized in that: It also comprises a temperature detection component (5) and a pressure detection component (6), wherein the temperature detection component (5) and the pressure detection component (6) are both arranged upstream of the throttle plate (12), the temperature detection component (5) is used to monitor the temperature of the supercritical carbon dioxide in real time, and the pressure detection component (6) is used to monitor the pressure of the supercritical carbon dioxide in real time.

5. The differential pressure supercritical carbon dioxide flowmeter according to claim 4, characterized in that: The upstream pressure-bearing chamber (131) is in communication with a measuring end of the pressure detection component (6).

6. A pressure differential supercritical carbon dioxide flow measurement method, characterized in that: The differential pressure supercritical carbon dioxide flowmeter according to any one of claims 1 to 5 comprises the following steps: Obtain the medium density of supercritical carbon dioxide; Obtaining the throttling pressure difference in the flow channel; Calculate the mass flow rate of supercritical carbon dioxide based on the medium density and throttling pressure difference.

7. The pressure differential supercritical carbon dioxide flow measurement method according to claim 6, characterized in that: Obtaining the medium density of supercritical carbon dioxide includes the following steps: Obtain the real-time temperature and real-time pressure of supercritical carbon dioxide; The medium density of the supercritical carbon dioxide is calculated according to the real-time temperature, the real-time pressure, and the corresponding relationship between the medium density of the supercritical carbon dioxide and the real-time temperature and the real-time pressure.

8. The pressure differential supercritical carbon dioxide flow measurement method according to claim 6, characterized in that: The calculation formula for the mass flow rate of supercritical carbon dioxide is: in, Q m is the mass flow rate of supercritical carbon dioxide; C is the outflow coefficient; ε is the fluid expansion coefficient; d is the inner diameter of the throttle hole; β is the ratio of the inner diameter of the flow channel to the inner diameter of the throttle hole; Δ p is the throttling pressure difference; ρ is the medium density.

9. A pressure differential supercritical carbon dioxide flow measurement device, characterized in that: include: A first processing unit is used to obtain the medium density of supercritical carbon dioxide; A second processing unit, used for obtaining a throttling pressure difference in the flow channel; The third processing unit is used to obtain the mass flow rate of supercritical carbon dioxide according to the medium density and the throttling pressure difference.

10. A computer-readable storage medium having a computer program stored thereon, characterized in that: When the computer program is executed by a processor, the steps of the pressure differential supercritical carbon dioxide flow measurement method according to any one of claims 6 to 8 are implemented.

11. A computer device comprising a memory, a processor and a computer program stored in the memory and executable on the processor, characterized in that: When the processor executes the computer program, the steps of the pressure differential supercritical carbon dioxide flow measurement method according to any one of claims 6 to 8 are implemented.

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