A carbon dioxide near critical point dynamic property test platform and test method

Abstract

The present application belongs to the technical field of carbon dioxide phase transition induced rock cracking, and provides a carbon dioxide near-critical point dynamic physical property testing platform and testing method, which comprises a carbon dioxide pressurizing and charging assembly, a carbon dioxide flow control assembly, an experimental pipeline, a gas circulation system and a data acquisition system. The carbon dioxide flow control assembly comprises a temperature regulator and an electromagnetic flowmeter which are sequentially connected, and the carbon dioxide pressurizing and charging assembly is communicated with the temperature regulator. The gas inlet end of the experimental pipeline is communicated with the electromagnetic flowmeter through an electromagnetic valve, and the gas outlet end of the experimental pipeline is communicated with a relief tank. The experimental pipeline and the relief tank are respectively provided with heating elements. The gas circulation system comprises a gas circulation pump, the gas inlet end of the gas circulation pump is communicated with the relief tank, and the gas outlet end of the gas circulation pump is communicated with the carbon dioxide pressurizing and charging assembly. The data acquisition system comprises a differential pressure sensor and a plurality of pressure sensors and temperature sensors. The present application can test the changes of the physical property parameters of carbon dioxide near-critical point, such as pressure, temperature, density, viscosity and specific heat capacity ratio.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of carbon dioxide phase transition induced rock, and particularly relates to a carbon dioxide near-critical point dynamic physical property test platform and a test method. BACKGROUND

[0002] In recent years, carbon dioxide has been widely used in many fields, such as unconventional reservoir stimulation and reconstruction, hydraulic engineering, urban infrastructure, etc. In these applications, dynamic monitoring of the physical property parameters of near-critical point carbon dioxide is of great significance to guide related technologies and research.

[0003] In the field of unconventional reservoir stimulation and reconstruction, carbon dioxide can form a miscible phase with reservoir oil and gas to reduce the viscosity of oil and gas, improve fluidity, and thus increase the recovery rate. In this process, carbon dioxide phase transition induced cracking is an important mechanism, and the change of the physical property parameters near the critical point of carbon dioxide will affect the phase transition process. In the carbon dioxide fracturing process, the injected liquid carbon dioxide will undergo phase transition to become gaseous in the formation, producing fracturing effect. Understanding the change of the physical property parameters near the critical point of carbon dioxide helps to optimize fracturing design and improve fracturing effect.

[0004] However, there is little research on the change of the physical property parameters of carbon dioxide along the way, and there is a lack of systematic experimental data and theoretical models. The study of the change of the physical property parameters near the critical point of carbon dioxide mainly relies on experimental measurement, and higher requirements are put forward for the precision and reliability of the measuring equipment due to the special pressure and temperature conditions. The existing carbon dioxide physical property test methods and devices have certain limitations and cannot be better applied to the dynamic change of the physical property parameters of carbon dioxide along the way. Therefore, there is an urgent need for a carbon dioxide near-critical point dynamic physical property test platform and test method that can measure temperature, pressure, density, viscosity, specific heat capacity ratio, etc. to help reveal the change law of the physical property parameters near the critical point of carbon dioxide, thereby providing important experimental data support for the application research in related fields. SUMMARY

[0005] The purpose of the present application is to provide a carbon dioxide near-critical point dynamic physical property test platform and test method to solve the above problems and achieve the purpose of testing the changes of the physical property parameters such as pressure, temperature, density, viscosity, and specific heat capacity ratio of carbon dioxide inside the carbon dioxide experimental pipeline.

[0006] To achieve the above purpose, the present application provides the following solution: a carbon dioxide near-critical point dynamic physical property test platform, comprising:

[0007] a carbon dioxide pressurizing and filling assembly;

[0008] The carbon dioxide flow control assembly comprises a temperature regulator and an electromagnetic flowmeter connected in sequence, the carbon dioxide pressurized filling assembly inputs carbon dioxide into the temperature regulator, and the electromagnetic flowmeter is used for measuring the amount of carbon dioxide passing through;

[0009] An experimental pipeline, an air inlet end of the experimental pipeline is communicated with an air outlet end of the electromagnetic flowmeter through an electromagnetic valve, an air outlet end of the experimental pipeline is communicated with a blow tank through a first connecting pipe, and heating members are arranged in the experimental pipeline and the blow tank respectively;

[0010] A gas circulation system, an air inlet end of the gas circulation pump is communicated with the blow tank through a second connecting pipe, and an air outlet end of the gas circulation pump is communicated with the carbon dioxide pressurized filling assembly;

[0011] A data acquisition system, a differential pressure sensor is arranged between the air inlet end and the air outlet end of the experimental pipeline, and a plurality of pressure sensors and temperature sensors are arranged in the experimental pipeline and the blow tank.

[0012] Preferably, the carbon dioxide pressurized filling assembly comprises a gas storage tank, an air outlet of the gas storage tank is communicated with a booster pump through a circulation tank, an air outlet end of the booster pump is communicated with the temperature regulator, the booster pump is used for pressurizing carbon dioxide gas and delivering the pressurized carbon dioxide gas into the temperature regulator, and an air outlet end of the gas circulation pump is communicated with the circulation tank.

[0013] Preferably, a buffer tank is communicated between the booster pump and the temperature regulator, and the buffer tank is used for stabilizing the flow, temperature and pressure of carbon dioxide entering the temperature regulator.

[0014] Preferably, the heating member comprises a heating tube, and the heating tubes are arranged in the experimental pipeline and the blow tank respectively, and the heating tube in the experimental pipeline is located at one end of the experimental pipeline.

[0015] Preferably, two groups of sensor mounting members are arranged on the side wall of the experimental pipeline, the two groups of sensor mounting members are symmetrically arranged about the axis of the experimental pipeline, the sensor mounting member comprises a plurality of mounting holes arranged on the side wall of the experimental pipeline, the plurality of mounting holes are equally spaced along the axis of the experimental pipeline, the plurality of mounting holes located on one side of the axis of the experimental pipeline are used for mounting the plurality of pressure sensors, and the plurality of mounting holes located on the other side of the axis of the experimental pipeline are used for mounting the plurality of temperature sensors.

[0016] Second mounting holes are arranged at both ends of the side wall of the experimental pipeline, and the two groups of second mounting holes are used for connecting the differential pressure sensor.

[0017] Preferably, the electromagnetic flowmeter is also connected with the pressure sensor and the temperature sensor.

[0018] Preferably, the cooling system is also provided, and the inlet end and the outlet end of the cooling system are connected with the second connecting pipe through a third connecting pipe and a fourth connecting pipe respectively, a fifth connecting pipe is connected between the first connecting pipe and the second connecting pipe close to one end of the relief tank, a first valve is connected on the first connecting pipe and close to the relief tank, a second valve and a third valve are connected on the fifth connecting pipe and the third connecting pipe respectively, and a fourth valve is connected on the second connecting pipe and between the third connecting pipe and the fourth connecting pipe.

[0019] A method for testing dynamic physical properties of carbon dioxide at a near critical point, and the operation steps include:

[0020] A plurality of pressure sensors, temperature sensors and differential pressure sensors are installed on the experimental pipeline, and the air tightness of the test platform is detected.

[0021] The air in the experimental pipeline and the relief tank is exhausted, and liquid carbon dioxide is filled into the experimental pipeline through a temperature regulator and an electromagnetic flowmeter by a carbon dioxide pressurizing and filling assembly.

[0022] The heating element is started, the carbon dioxide in the experimental pipeline is heated to a critical state, and the measurement values of each sensor are recorded for calculating the physical property parameters of the carbon dioxide at the critical state in the experimental pipeline.

[0023] Compared with the prior art, the present application has the following advantages and technical effects:

[0024] 1. The test platform of the present application can effectively test the changes of temperature and pressure of carbon dioxide at a near critical point at the same time, and the obtained data is beneficial for analyzing the changes of physical property parameters along the experimental pipeline.

[0025] 2. The test platform of the present application can obtain the changes of viscosity and density at different positions in the pipeline according to the changes of temperature and pressure detected in the experimental pipeline.

[0026] 3. The test platform of the present application can determine the specific heat capacity ratio of carbon dioxide by connecting a relief tank at the gas outlet end of the experimental pipeline. BRIEF DESCRIPTION OF DRAWINGS

[0027] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the drawings needed in the embodiments will be briefly introduced below. Obviously, the drawings in the following description are only some embodiments of the present application, and other drawings can also be obtained by those skilled in the art without creative labor.

[0028] Figure 1 The connection diagram between the components of the test platform of the application is shown in the figure;

[0029] 1, gas storage tank; 2, circulating tank; 3, booster pump; 4, buffer tank; 5, temperature regulator; 6, electromagnetic flowmeter; 7, heating tube; 8, relief tank; 9, cooling system; 10, gas circulating pump; 11, heating core temperature control box; 12, flow control system; 13, data display terminal; 14, data acquisition instrument; 15-1, first valve; 15-2, second valve; 15-3, third valve; 15-4, fourth valve; 16, signal cable; 17, experimental pipeline; 18, gas circulating pump controller; 19, pressure sensor; 20, temperature sensor; 21, differential pressure sensor; 22, first connecting pipe; 23, second connecting pipe; 24, third connecting pipe; 25, fourth connecting pipe; 26, fifth connecting pipe. DETAILED DESCRIPTION

[0030] The technical solutions in the embodiments of the application will be described clearly and completely below with reference to the drawings in the embodiments of the application. Obviously, the described embodiments are only part of the embodiments of the application, rather than all the embodiments of the application. Based on the embodiments in the application, all other embodiments obtained by those skilled in the art without creative work fall within the scope of protection of the application.

[0031] In order to make the above-mentioned purposes, features and advantages of the application more obvious and easy to understand, the application will be further described in detail below with reference to the drawings and specific embodiments.

[0032] Embodiment one:

[0033] Reference Figure 1 The application provides a carbon dioxide near-critical point dynamic property test platform, which comprises:

[0034] A carbon dioxide pressurizing and filling assembly;

[0035] A carbon dioxide flow control assembly, which comprises a temperature regulator 5 and an electromagnetic flowmeter 6 connected in sequence, the carbon dioxide pressurizing and filling assembly inputs carbon dioxide into the temperature regulator 5, and the electromagnetic flowmeter 6 is used for measuring the amount of the passing carbon dioxide;

[0036] An experimental pipeline 17, the gas inlet end of the experimental pipeline 17 is communicated with the gas outlet end of the electromagnetic flowmeter 6 through an electromagnetic valve, the gas outlet end of the experimental pipeline 17 is communicated with the relief tank 8 through the first connecting pipe 22, and heating members are arranged in the experimental pipeline 17 and the relief tank 8 respectively;

[0037] The gas circulation system comprises a gas circulation pump 10, the gas inlet end of the gas circulation pump 10 is communicated with the relief tank 8 through a second connecting pipe 23, and the gas outlet end of the gas circulation pump 10 is communicated with the carbon dioxide pressurizing and filling assembly.

[0038] The data acquisition system comprises a differential pressure sensor 21 arranged between the gas inlet end and the gas outlet end of the experimental pipeline 17 and a plurality of pressure sensors 19 and temperature sensors 20 arranged in the experimental pipeline 17 and the relief tank 8.

[0039] The main function of the carbon dioxide pressurizing and filling assembly is to deliver pressurized carbon dioxide gas to the temperature regulator 5; the main function of the temperature regulator 5 is to keep the carbon dioxide at constant pressure and temperature; the main function of the electromagnetic flowmeter 6 is to measure the flow of the passing carbon dioxide, so that the required mass of carbon dioxide enters the experimental pipeline 17; the main function of the heating element is to heat the carbon dioxide in the experimental pipeline 17 to the critical state; and the main function of the gas circulation pump 10 is to circulate the carbon dioxide after the test among the components. Overall, the present application can effectively test the changes of the temperature and pressure of the carbon dioxide at the near-critical point at the same time, and obtain the viscosity and density changes at different positions in the pipeline according to the detected temperature and pressure changes in the pipeline; at the same time, by connecting the relief tank to the gas outlet end of the experimental pipeline, the specific heat capacity ratio of the carbon dioxide can be determined by the adiabatic expansion method.

[0040] In a further optimization scheme, the gas circulation pump 10 is further electrically connected with a gas circulation pump controller 18.

[0041] In a further optimization scheme, the carbon dioxide pressurizing and filling assembly comprises a gas storage tank 1, the gas outlet of the gas storage tank 1 is communicated with a circulating tank 2 through a pressurizing pump 3, the gas outlet end of the pressurizing pump 3 is communicated with the temperature regulator 5, the pressurizing pump 3 is used for pressurizing the carbon dioxide gas and delivering the pressurized carbon dioxide gas to the temperature regulator 5, and the gas outlet end of the gas circulation pump 10 is communicated with the circulating tank 2.

[0042] The main function of the gas storage tank 1 is to store the carbon dioxide gas source, the storage temperature is-20℃, the storage pressure is 2.2MPa, and the liquid carbon dioxide with a discharge pressure of 2MPa can be discharged. The pressurizing pump 3 can increase the liquid carbon dioxide from 2MPa to 7-12MPa and deliver the liquid carbon dioxide to the temperature regulator 5.

[0043] In a further optimization scheme, a buffer tank 4 is communicated between the pressurizing pump 3 and the temperature regulator 5, and the buffer tank 4 is used for stabilizing the flow, temperature and pressure of the carbon dioxide entering the temperature regulator 5.

[0044] In a further optimization scheme, the pressurizing pump 3, the buffer tank 4, the temperature regulator 5 and the electromagnetic flowmeter 6 are respectively electrically connected with a flow control system 12.

[0045] Further optimization scheme, the heating element includes heating tube 7, the experimental pipeline 17 and the relief tank 8 are respectively provided with heating tube 7, and the heating tube 7 in the experimental pipeline 17 is located at one end of the experimental pipeline 17.

[0046] Further optimization scheme, two groups of heating tubes 7 are respectively electrically connected with heating core temperature control box 11.

[0047] Further optimization scheme, two groups of sensors mounting parts are formed on the side wall of the experimental pipeline 17, the two groups of sensors mounting parts are symmetrically arranged about the axis of the experimental pipeline 17, the sensor mounting part includes a plurality of mounting holes formed on the side wall of the experimental pipeline 17, the plurality of mounting holes are equally spaced along the axis of the experimental pipeline 17, the plurality of mounting holes located on one side of the axis of the experimental pipeline 17 are used for mounting a plurality of pressure sensors 19, and the plurality of mounting holes located on the other side of the axis of the experimental pipeline 17 are used for mounting a plurality of temperature sensors 20.

[0048] Second mounting holes are formed at both ends of the side wall of the experimental pipeline 17, and the two groups of second mounting holes are used for connecting differential pressure sensors 21.

[0049] The pressure sensor 19 is a piezoelectric pressure sensor. Figure 1 As shown, through the plurality of first mounting holes, the plurality of pressure sensors 19 are fixedly connected to one side of the experimental pipeline 17, and the plurality of temperature sensors 20 are fixedly connected to the other side of the experimental pipeline 17.

[0050] During the experiment, after the experimental pipeline 17 is fixed to the support (not shown in the figure), all the pressure sensors 19 are located on the same horizontal line, and all the temperature sensors 20 are also located on the same horizontal line.

[0051] The positions of the plurality of pressure sensors 19 and the plurality of temperature sensors 20 installed on the experimental pipeline 17 and the relief tank 8 need to ensure that the carbon dioxide therein can immerse the contact rods of the temperature sensors and the contact holes of the pressure sensors.

[0052] Further optimization scheme, the electromagnetic flowmeter 6 and the experimental pipeline 17 are further communicated with the pressure sensor 19 and the temperature sensor 20.

[0053] Further optimization scheme, the differential pressure sensor 21, the plurality of pressure sensors 19 and the plurality of temperature sensors 20 are respectively electrically connected with the data acquisition instrument 14, and the data acquisition instrument 14 is electrically connected with the data display terminal 13.

[0054] Further optimization scheme, as shown in Figure 1As shown, the several temperature sensors 20 on the experimental pipeline 17 and the several pressure sensors 19 on the experimental pipeline 17 are respectively electrically connected through the signal cables 16, and the data acquisition instrument 14 realizes electrical connection with the several pressure sensors 19 and the temperature sensors 20 through the two groups of signal cables 16.

[0055] Further optimization scheme, it also includes cooling system 9, the inlet end and the outlet end of cooling system 9 are communicated with second connecting pipe 23 through third connecting pipe 24 and fourth connecting pipe 25 respectively, and the first connecting pipe 22 is communicated with the end of second connecting pipe 23 close to the release tank 8 between fifth connecting pipe 26, the first connecting pipe 22 is communicated with first valve 15-1, and the first valve 15-1 is arranged close to the release tank 8, the second valve 15-2 and the third valve 15-3 are respectively communicated on the fifth connecting pipe 26 and the third connecting pipe 24, the fourth valve 15-4 is communicated on the second connecting pipe 23, and the fourth valve 15-4 is located between the third connecting pipe 24 and the fourth connecting pipe 25.

[0056] A kind of carbon dioxide near critical point dynamic property test method, operating steps include:

[0057] Several pressure sensors 19, temperature sensors 20 and differential pressure sensors 21 are installed to experimental pipeline 17, and the air tightness of test platform is detected;

[0058] The air in experimental pipeline 17 and release tank 8 is exhausted, and liquid carbon dioxide is filled into experimental pipeline 17 through temperature regulator 5 and electromagnetic flowmeter 6 by carbon dioxide pressurizing and filling assembly;

[0059] Start heating part, heat carbon dioxide in experimental pipeline 17 to critical state, record the measurement value of each sensor, for calculating the various physical parameters of carbon dioxide critical in experimental pipeline 17.

[0060] Example two:

[0061] According to the carbon dioxide near critical point dynamic property test method of example one, the density measurement method of carbon dioxide includes:

[0062] The liquid carbon dioxide gas in the gas tank 1 is pressurized by the pressurizing pump 3 and then enters the temperature regulator 5 to ensure that the experimental gas is at a constant pressure and temperature. After pressurization and temperature increase, the required mass of carbon dioxide at the predicted temperature and pressure enters the experimental pipeline 17. After reaching the experimental pressure, the electromagnetic valve between the electromagnetic flowmeter 6 and the experimental pipeline 17 is closed. The temperature of the carbon dioxide in the experimental pipeline 17 is changed by using the heating tube 7 to reach the critical state. The temperature, pressure and differential pressure of the test section of the experimental pipeline 17 at this time are dynamically recorded. After the recording is completed, the first valve 15-1, the third valve 15-3 are opened and the gas circulating pump 10 is started. The experimental gas flows out of the test section of the experimental pipeline 17 and enters the cooling system 9 for cooling. After cooling, the experimental gas is pressurized and circulated by the gas circulating pump 10 and enters the circulating tank 2 for the next experiment. During the experiment, the various readings of the test section of the experimental pipeline 17 during the flow process, including pressure, temperature, differential pressure, etc., are collected and recorded in real time through the data display terminal 13.

[0063] The experiment first calibrates the differential pressure using the density of pure water to obtain the density and pressure difference at a known temperature and pressure. The carbon dioxide in the pipe is measured in the same way, and the density of the carbon dioxide is finally calculated.

[0064] Example Three

[0065] According to the dynamic physical property test method of carbon dioxide near the critical point of Example One, the method of carbon dioxide includes:

[0066] The liquid carbon dioxide gas in the gas tank 1 is pressurized by the pressurizing pump 3 and then enters the temperature regulator 5 to ensure that the experimental gas is at a constant pressure and temperature. After pressurization and temperature increase, the required mass of carbon dioxide at the predicted temperature and pressure enters the experimental pipeline 17. After reaching the experimental pressure, the electromagnetic valve between the electromagnetic flowmeter 6 and the experimental pipeline 17 is closed. The temperature of the carbon dioxide in the experimental pipeline 17 is changed by using the heating tube 7 to reach the critical state. The temperature, pressure and differential pressure of the test section of the experimental pipeline 17 at this time are dynamically recorded. After the recording is completed, the first valve 15-1, the third valve 15-3 are opened and the gas circulating pump 10 is started. The experimental gas flows out of the test section of the experimental pipeline 17 and enters the cooling system 9 for cooling. After cooling, the experimental gas is pressurized and circulated by the gas circulating pump 10 and enters the circulating tank 2 for the next experiment. During the experiment, the various readings of the test section of the experimental pipeline 17 during the flow process, including pressure, temperature, differential pressure, etc., are collected and recorded in real time through the data display terminal 13.

[0067] According to the measured density at different temperature and pressure and the pressure difference of the measurement section under the experimental conditions, the temperature T, pressure P, flow rate v, length L of the section, and inner diameter d are recorded during the experiment. Finally, the viscosity of the carbon dioxide is calculated.

[0068] Example Four

[0069] According to the dynamic property testing method of carbon dioxide near the critical point of embodiment one, the specific heat capacity ratio measurement method of carbon dioxide in the experimental pipeline 17 includes:

[0070] The liquid carbon dioxide gas in the gas storage tank 1 is pressurized by the booster pump 3 and enters the temperature regulator 5 to ensure that the experimental gas is at a constant pressure and temperature. After pressurization and warming, the required mass of carbon dioxide at the predicted temperature and pressure enters the experimental pipeline 17. After reaching the experimental pressure, the electromagnetic valve between the electromagnetic flowmeter 6 and the experimental pipeline 17 is closed. The carbon dioxide in the experimental pipeline 17 reaches the required measurement temperature and pressure by the heating tube 7, and the gas in the vent tank 8 is emptied. The temperature in the vent tank 8 is heated to be consistent with the temperature in the experimental pipeline 17. After the pressure stabilizes, the current temperature T0 and pressure P1 are recorded. Then, the first valve 15-1 is suddenly opened, and the pressure in the experimental pipeline 17 will rapidly decrease, while the temperature and pressure changes in the vent tank 8 are monitored. This process needs to be fast and is considered to be adiabatic. When the pressure in the experimental pipeline 17 is consistent with the pressure in the vent tank 8, the first valve 15-1 is closed, and the pressure P0 and temperature T1 of the process are recorded. The temperature in the experimental pipeline 17 is raised to T0 by the heating tube 7, and the pressure change P2 in the pipeline is recorded. Finally, the specific heat capacity ratio in the pipeline is calculated based on the obtained parameters.

[0071] Embodiment five:

[0072] According to the dynamic property testing method of carbon dioxide near the critical point of embodiment one, the testing method of constant volume specific heat capacity and constant pressure specific heat capacity includes:

[0073] The liquid carbon dioxide gas in the gas storage tank 1 is pressurized by the booster pump 3 and enters the temperature regulator 5 to ensure that the experimental gas is at a constant pressure and temperature. After pressurization and warming, the required mass of carbon dioxide at the predicted temperature and pressure enters the experimental pipeline 17. After reaching the experimental pressure, the electromagnetic valve between the electromagnetic flowmeter 6 and the experimental pipeline 17 is closed. The temperature of carbon dioxide in the experimental pipeline 17 is changed by the heating tube 7 to reach the critical state, and the current pressure P0 and temperature T0 are recorded. Then, heating is performed by the heating tube 7, and the heating amount is recorded as Q. After the pressure and temperature in the experimental pipeline 17 stabilize, the temperature T1 in the pipeline is recorded. Finally, the constant pressure specific heat capacity and the constant volume specific heat capacity are calculated based on the obtained parameters.

[0074] In the description of the present application, it needs to be understood that the terms "longitudinal", "transverse", "upper", "lower", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer" and the like indicate the orientation or positional relationship shown in the drawings, which are only for the convenience of describing the present application, and do not indicate or imply that the device or element referred to must have a particular orientation, be constructed and operated in a particular orientation, and therefore cannot be understood as a limitation on the present application.

[0075] The above-described embodiments are only to describe the preferred modes of the present application, and not to limit the scope of the present application. Without departing from the design spirit of the present application, various modifications and improvements to the technical solutions of the present application made by those skilled in the art shall fall within the protection scope determined by the claims of the present application.

Claims

1. A platform for testing dynamic properties of carbon dioxide near the critical point, characterized in that, include: Carbon dioxide pressurized filling assembly; A carbon dioxide flow control assembly includes a temperature regulator (5) and an electromagnetic flow meter (6) connected in sequence. The carbon dioxide pressurization and filling assembly inputs carbon dioxide into the temperature regulator (5), and the electromagnetic flow meter (6) is used to measure the amount of carbon dioxide passing through. The experimental pipeline (17) has an inlet end connected to the outlet end of the electromagnetic flowmeter (6) via a solenoid valve. The outlet end of the experimental pipeline (17) is connected to a discharge tank (8) via a first connecting pipe (22). Heating elements are respectively installed in the experimental pipeline (17) and the discharge tank (8). The gas circulation system includes a gas circulation pump (10), the inlet of which is connected to the vent tank (8) via a second connecting pipe (23), and the outlet of which is connected to the carbon dioxide pressurization and filling assembly. The data acquisition system includes a differential pressure sensor (21) installed between the inlet and outlet of the experimental pipeline (17) and several pressure sensors (19) and temperature sensors (20) installed in the experimental pipeline (17) and the relief tank (8). The carbon dioxide pressurization and filling assembly includes a gas storage tank (1), the outlet of the gas storage tank (1) is connected to a booster pump (3) through a circulation tank (2), the outlet of the booster pump (3) is connected to the temperature regulator (5), the booster pump (3) is used to pressurize carbon dioxide gas and deliver it to the temperature regulator (5), and the outlet of the gas circulation pump (10) is connected to the circulation tank (2). Two sets of sensor mounting components are provided on the side wall of the experimental pipeline (17). The two sets of sensor mounting components are symmetrically arranged about the axis of the experimental pipeline (17). The sensor mounting components include a number of mounting holes opened on the side wall of the experimental pipeline (17). The number of mounting holes are equally spaced along the axis of the experimental pipeline (17). The number of mounting holes located on one side of the axis of the experimental pipeline (17) is used to install a number of pressure sensors (19), and the number of mounting holes located on the other side of the axis of the experimental pipeline (17) is used to install a number of temperature sensors (20). The experimental pipeline (17) has second mounting holes at both ends of its sidewall, and the two sets of second mounting holes are used to connect the differential pressure sensor (21).

2. The platform for dynamic property measurement of carbon dioxide near the critical point according to claim 1, characterized in that: A buffer tank (4) is connected between the booster pump (3) and the temperature regulator (5). The buffer tank (4) is used to stabilize the flow rate, temperature and pressure of carbon dioxide entering the temperature regulator (5).

3. The platform for dynamic property measurement of carbon dioxide near the critical point according to claim 1, characterized in that: The heating element includes a heating tube (7), and the heating tube (7) is respectively installed in the experimental pipeline (17) and the venting tank (8). The heating tube (7) in the experimental pipeline (17) is located at one end of the experimental pipeline (17).

4. The platform for dynamic property measurement of carbon dioxide near the critical point according to claim 1, characterized in that: The electromagnetic flowmeter (6) is also connected to the experimental pipeline (17) by the pressure sensor (19) and the temperature sensor (20).

5. The platform for dynamic property measurement of carbon dioxide near the critical point according to claim 1, wherein: The cooling system (9) is also included, and the inlet end and the outlet end of the cooling system (9) are communicated with the second connecting pipe (23) through the third connecting pipe (24) and the fourth connecting pipe (25) respectively, the fifth connecting pipe (26) is communicated between the first connecting pipe (22) and one end of the second connecting pipe (23) close to the relief tank (8), the first valve (15-1) is communicated on the first connecting pipe (22), the first valve (15-1) is arranged close to the relief tank (8), the second valve (15-2) and the third valve (15-3) are respectively communicated on the fifth connecting pipe (26) and the third connecting pipe (24), the fourth valve (15-4) is communicated on the second connecting pipe (23), and the fourth valve (15-4) is located between the third connecting pipe (24) and the fourth connecting pipe (25).

6. A method for testing dynamic properties of carbon dioxide near the critical point, based on the carbon dioxide near the critical point dynamic property testing platform of claim 1, characterized in that, The operation steps include: A plurality of pressure sensors (19), temperature sensors (20) and differential pressure sensors (21) are installed on the experimental pipeline (17), and the air tightness of the test platform is detected; The air in the experimental pipeline (17) and the relief tank (8) is exhausted, and the liquid carbon dioxide is filled into the experimental pipeline (17) through the temperature regulator (5) and the electromagnetic flowmeter (6) by the carbon dioxide pressurizing and filling assembly; The heating element is started, the carbon dioxide in the experimental pipeline (17) is heated to the critical state, and the measurement values of the sensors are recorded for calculating the physical property parameters of the carbon dioxide in the experimental pipeline (17) at the critical state.

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