System and method for studying dynamic mixing uniformity of supercritical carbon dioxide and associated gas

Abstract

The application discloses a supercritical carbon dioxide and associated gas dynamic mixing uniformity research system and method, and belongs to the field of oilfield associated gas and supercritical CO2 mixing. The system comprises the following units: a fluid supply unit for injecting liquid carbon dioxide into a supercritical carbon dioxide preparation unit; a supercritical CO2 preparation unit for preparing liquid carbon dioxide into supercritical carbon dioxide and conveying the supercritical carbon dioxide to a mixing development unit; an associated gas injection unit for injecting methane into the mixing development unit; a mixing development unit for dynamically mixing the supercritical carbon dioxide and the methane; and a detection unit for detecting the methane concentration and observing the mixing and stratification of the supercritical CO2 and the methane mixture. The system can obtain the sensitivity and combination effect of various variables and realize the exploration of the dynamic mixing characteristics of the supercritical CO2 and the methane gas by changing the injection ratio, flow control and high-pressure-resistant pipeline of the CO2 and the methane.

Description

TECHNICAL FIELD

[0001] The present application belongs to the field of oilfield associated gas and supercritical CO2 mixing, and particularly relates to a supercritical carbon dioxide and associated gas dynamic mixing uniformity research system and method. BACKGROUND

[0002] The information disclosed in this Background section is for the purpose of increasing an understanding of the general context of the present application and is not necessarily recognized in any form as an admission that this information constitutes prior art.

[0003] In oilfield production, CO2 injection into the formation for oil displacement is an economic measure for controlling CO2 emission. The injection of CO2 not only improves the oil recovery rate, but also realizes the permanent storage of greenhouse gas CO2. However, after CO2 is injected into the well, about 40% to 50% of CO2 returns to the ground with oilfield associated gas, and the obtained gas is a mixture of the two. At a high pressure of more than 7.38 MPa, CO2 is in a supercritical state, and natural gas is in a gaseous state. There is a certain density difference between the two, and the mixing of the two is unknown. In the existing research and simulation of CO2 related mixtures, gas-gas mixing, liquid-liquid mixing, and gas-liquid mixing have been explored. However, the dynamic mixing uniformity of CO2 in a supercritical state and associated gas cannot be obtained by simulation and needs to be studied by reliable experiments. SUMMARY

[0004] In order to solve the problems of the prior art, the purpose of the present application is to provide a supercritical carbon dioxide and associated gas dynamic mixing uniformity research system and method. The system of the present application can study the dynamic mixing uniformity of CO2 in a supercritical state and associated gas, fill the gap in the prior art, and solve the problem that simulation cannot be performed.

[0005] In order to achieve the above-mentioned purpose, the technical scheme of the present application is as follows:

[0006] In a first aspect of the present application, a supercritical carbon dioxide and associated gas dynamic mixing uniformity research system is provided, comprising:

[0007] A fluid supply unit comprising a liquid CO2 storage device, an injection pump connected in sequence, for injecting liquid carbon dioxide into a supercritical carbon dioxide preparation unit;

[0008] A supercritical CO2 preparation unit comprising a hydraulic oil supply system, a piston, a supercritical CO2 preparation device, and a first pressure reducing valve connected in sequence, for preparing liquid carbon dioxide into supercritical carbon dioxide and delivering it to a mixing development unit;

[0009] The associated gas injection unit comprises, in sequence, an oilfield associated gas storage device and a second pressure reducing valve, and is used for injecting the oilfield associated gas into the mixing development unit.

[0010] The mixing development unit comprises a high-pressure-resistant pipeline with both ends sealed and a high-pressure-resistant window arranged on the wall of the high-pressure-resistant pipeline and used for dynamically mixing the supercritical carbon dioxide and the oilfield associated gas.

[0011] The detection unit comprises an oilfield associated gas concentration detection device and a high-speed camera arranged outside the high-pressure-resistant pipeline, and is used for detecting the concentration of the oilfield associated gas at the position through the high-pressure-resistant window and observing the mixing and layering of the supercritical CO2 and the oilfield associated gas mixture.

[0012] In some embodiments of the present application, an electric heat tracing device is arranged along the inner wall inside the supercritical CO2 generator, and the electric heat tracing device comprises a heating resistor, a temperature sensor and a pressure sensor, and is used for accurately detecting and regulating the temperature and pressure inside the supercritical CO2 generator.

[0013] In some embodiments of the present application, a cement foundation is arranged at the bottom of the supercritical CO2 generator, so as to improve the stability of the supercritical CO2 generator, reduce the influence of environmental factors on the device and reduce errors.

[0014] In some embodiments of the present application, the piston is arranged inside the supercritical CO2 generator, the cross section of the piston is consistent with the cross section of the supercritical CO2 generator, and the piston is horizontally movable inside the supercritical CO2 generator. The size of the space inside the supercritical CO2 generator is controlled by the movement of the piston, so as to realize the control of the pressure inside the supercritical CO2 generator. The hydraulic oil in the hydraulic oil supply system enters the bottom of the piston and then pushes the piston to move. The present application cooperates the hydraulic oil supply system and the piston, controls the volume inside the supercritical CO2 generator, realizes the accurate regulation and control of the pressure inside the supercritical CO2 generator, and also realizes the constant-pressure control inside the supercritical CO2 generator.

[0015] In some embodiments of the present application, the supercritical CO2 generator is further provided with a safety valve.

[0016] In some embodiments of the present application, three groups of opposite high-pressure-resistant windows are arranged at different positions at the same horizontal height of the front and rear sides of the high-pressure-resistant pipeline, and each group comprises two high-pressure-resistant windows. The high-pressure-resistant windows are transparent and are used for visual observation, high-speed camera image acquisition and component analysis.

[0017] In some embodiments of the present application, the supercritical CO2 prepared by the supercritical CO2 preparation unit and the associated gas output by the associated gas injection unit are mixed by a tee joint and then enter the mixing development unit. The tee joint is arranged on the pipeline between the first pressure reducing valve and the mixing development unit.

[0018] In some embodiments of the present application, the mixing development unit further comprises an output valve for outputting the mixture of supercritical CO2 and oilfield associated gas. The opening degree of the output valve can be controlled to control the flow rate of the mixture of supercritical CO2 and oilfield associated gas.

[0019] In some embodiments of the present application, the oilfield associated gas concentration detection device is a laser methane remote sensor.

[0020] In a second aspect of the present application, a research method using the above-mentioned supercritical CO2 and associated gas dynamic mixing uniformity research system is provided, which comprises the following steps:

[0021] Step 1: liquid CO2 is injected from the liquid CO2 storage device into the supercritical CO2 preparation device by using an injection pump, and the temperature and pressure are controlled to make the liquid CO2 change into dense-phase CO2, and then the temperature is increased to make the dense-phase CO2 change into supercritical CO2;

[0022] Step 2: the supercritical CO2 output from the supercritical CO2 preparation device is mixed with the methane output from the oilfield associated gas storage device by a tee joint after being reduced by the first pressure reducing valve and the second pressure reducing valve, and then the mixture is injected into a high-pressure-resistant pipeline with both ends sealed;

[0023] Step 3: after the mixture of supercritical CO2 and associated gas flows stably in the high-pressure-resistant pipeline, the methane concentration at different positions is detected by using a laser methane remote sensor through transparent high-pressure-resistant windows at different positions, and the methane concentration at different positions is recorded;

[0024] Step 4: after the mixture of supercritical CO2 and associated gas flows stably in the high-pressure-resistant pipeline, the mixing and layering of the mixture of supercritical CO2 and associated gas is observed directly through the high-pressure-resistant windows or by using a high-speed camera;

[0025] Step 5: different flow rates are controlled by using the output valve at the rear part of the high-pressure-resistant pipeline, the methane concentration at different positions under different flow rates is obtained, and the dynamic mixing of the mixture of supercritical CO2 and associated gas under different flow rates is analyzed;

[0026] Step 6: after the dynamic mixing of the mixture of supercritical CO2 and associated gas under different flow rates at a certain pipe diameter is tested, a high-pressure-resistant pipeline with a different diameter is replaced to retest the dynamic mixing of the mixture of supercritical CO2 and associated gas under different pipe diameters;

[0027] Step 7, the sensitivity analysis of the variable affecting the dynamic mixing of the supercritical CO2 and the associated gas mixture is carried out, and the optimal variable combination of the dynamic mixing of the supercritical CO2 and the associated gas mixture is obtained.

[0028] In some embodiments of the present application, in step 1, the process of supercritical CO2 preparation needs to be controlled in combination with the CO2 phase diagram.

[0029] The liquid CO2 is injected into the supercritical CO2 preparation device, the hydraulic oil in the hydraulic oil supply system is used to push the piston to move and realize pressure control, and the specific setting pressure is 6 MPa; the temperature is controlled by the electric heating and heat preservation device to ensure that the CO2 liquid in the supercritical CO2 preparation device is in a liquid phase until the piston is pushed to the bottom of the supercritical CO2 preparation device and the internal volume of the supercritical CO2 preparation device reaches the maximum; thereafter, the liquid CO2 is continuously injected into the supercritical CO2 preparation device to continuously increase the pressure in the supercritical CO2 preparation device until the critical pressure is exceeded, and the liquid CO2 is converted into dense-phase CO2; after the injection is completed, the temperature is raised, and the temperature is raised by the electric heating and heat preservation device to make the dense-phase CO2 warm and convert into supercritical CO2. The liquid CO2 is converted into dense-phase CO2 by the pressure increase in the liquid CO2 injection process, and the phase state of the dense-phase CO2 is converted into supercritical CO2 by the temperature increase, thereby ensuring the controllability and safety of the liquid CO2 injection process.

[0030] In some embodiments of the present application, in step 2, when the supercritical CO2 is mixed with the oilfield associated gas, the first pressure reducing valve and the second pressure reducing valve are opened at the same time and the opening degree is controllable, and the injection rate of the supercritical CO2 and the oilfield associated gas into the high-pressure resistant pipeline is uniform.

[0031] In some embodiments of the present application, in step 7, the variable includes the pipe diameter of the high-pressure resistant pipeline, the flow of the supercritical CO2 and the oilfield associated gas.

[0032] The present application has the following beneficial effects:

[0033] Since the mixing characteristics of the fluid in the supercritical state are unknown, the present application directly mixes the supercritical CO2 and the oilfield associated gas through the three-way valve after the supercritical CO2 and the oilfield associated gas are reduced by the first pressure reducing valve and the second pressure reducing valve respectively, and then the dynamic mixing of the two is realized after the mixture enters the high-pressure resistant pipeline and fully develops, and the sensitivity and combination effect of various variables can be obtained by changing the injection ratio of CO2 and the oilfield associated gas, the flow control, and the high-pressure resistant pipeline, thereby realizing the exploration of the dynamic mixing characteristics of the supercritical CO2 and the oilfield associated gas, and providing a reliable research device and reliable experimental data for engineering application and research. BRIEF DESCRIPTION OF DRAWINGS

[0034] The drawings constituting a part of this disclosure serve to provide further understanding of the present application, the illustrative embodiments of the present application and their descriptions serve to explain the present application, and do not constitute an improper limitation on the present application.

[0035] Figure 1 Structure diagram of the supercritical carbon dioxide and associated gas dynamic mixing uniformity research system of the present application;

[0036] Figure 2 Flow chart of the supercritical carbon dioxide and associated gas dynamic mixing uniformity research method of the present application;

[0037] Figure 3 Carbon dioxide phase diagram.

[0038] 1: liquid CO2 Dewar flask, 2: injection pump, 3: supercritical CO2 preparation device, 4: electric heat tracing device, 5: CNG bottle, 6: safety valve, 7: hydraulic oil supply system, 8: piston, 9: first pressure reducing valve, 10: second pressure reducing valve, 11: tee, 12: high-pressure resistant pipeline, 13: opposite transparent window, 14: laser methane remote meter, 15: high-speed camera, 16: cement foundation, 17: output valve. DETAILED DESCRIPTION

[0039] In order to enable those skilled in the art to more clearly understand the technical solutions of the present application, the technical solutions of the present application will be described in detail below in combination with specific embodiments.

[0040] Embodiment 1

[0041] As shown in the accompanying drawings, Figure 1 A supercritical carbon dioxide and associated gas dynamic mixing uniformity research system and method, including a fluid supply unit, a supercritical CO2 preparation unit, an associated gas injection unit, a mixing development unit, a detection unit, and a data acquisition and processing unit.

[0042] The fluid supply unit includes a liquid CO2 Dewar flask 1 and an injection pump 2. The liquid CO2 Dewar flask 1 is provided with a display that can display the output mass of liquid CO2 in real time, and the mass of liquid CO2 injected into the supercritical CO2 preparation device 3 can be observed in real time through the display.

[0043] The supercritical CO2 preparation unit includes a supercritical CO2 preparation device 3, a first pressure reducing valve 4, a hydraulic oil supply system 7, a piston 8, an electric heat tracing device 4, a safety valve 6, and a cement foundation 16.

[0044] The associated gas injection unit includes a CNG bottle 5 and a second pressure reducing valve 10.

[0045] The mixing development unit includes a tee 11, a high-pressure resistant pipeline 12 sealed at both ends, a high-pressure resistant window 13, and a delivery valve 17.

[0046] The data acquisition and processing unit is connected to an external computer system.

[0047] The specific connection mode of the device is as follows:

[0048] The liquid CO2 provided by the liquid CO2 Dewar 1 is injected into the supercritical CO2 preparation device 3 in the supercritical CO2 preparation unit through the injection pump 2. The inner wall of the supercritical CO2 preparation device 3 is provided with an electric heating and heat preservation device 4, which includes a heating resistor, a temperature sensor and a pressure sensor. The supercritical CO2 preparation device 3 is provided with a cement foundation 16 at the bottom to ensure its stability.

[0049] The supercritical CO2 preparation device 3 is horizontal, and the length of the internal reaction space is greater than the height. The hydraulic oil supply system 7 is connected to the piston 8 through the oil pipeline. The piston 8 is arranged in the supercritical CO2 preparation device 3, and the cross section of the piston 8 is consistent with the cross section of the internal reaction space of the supercritical CO2 preparation device 3. The piston 8 can move horizontally in the supercritical CO2 preparation device 3. By moving the piston 8, the size of the internal reaction space of the supercritical CO2 preparation device 3 is controlled, and the internal pressure of the supercritical CO2 preparation device 3 is controlled. The hydraulic oil in the hydraulic oil supply system 7 enters the bottom of the piston 8 to drive the piston to move, thereby controlling the internal pressure of the supercritical CO2 preparation device 3.

[0050] The supercritical CO2 preparation device 3 can be vertical, and the piston 8 is arranged at the bottom of the supercritical CO2 preparation device 3 and can move up and down in the supercritical CO2 preparation device 3. The hydraulic oil in the hydraulic oil supply system 7 enters the bottom of the piston 8 to drive the piston 8 to rise, thereby realizing the variable volume of the supercritical CO2 preparation device 3 and realizing the pressure control.

[0051] The safety valve 6 is arranged on the side wall of the supercritical CO2 preparation device 3.

[0052] The supercritical CO2 output pipeline of the supercritical CO2 preparation device 3 is provided with the first pressure reducing valve 9. The CNG bottle 5 supplies compressed natural gas, and the output pipeline thereof is provided with the second pressure reducing valve 10. The supercritical CO2 output by the first pressure reducing valve 9 and the natural gas output by the second pressure reducing valve 10 are mixed together through the three-way joint 11 and then transported into the high-pressure-resistant pipeline 12 with a transparent high-pressure-resistant window 13.

[0053] The mixing development unit is equipped with a measuring unit, which includes a laser methane remote sensor 14 arranged outside the transparent high-pressure-resistant window 13 of the high-pressure-resistant pipeline 12, and a high-speed camera 15. The laser methane remote sensor 14 is used to detect the concentration of natural gas at the position of the transparent high-pressure-resistant window 13, and the high-speed camera 15 is used to observe the mixing and layering of the supercritical CO2 and natural gas mixture at the transparent high-pressure-resistant window 13.

[0054] The data acquisition and processing unit is an external computer system, which is used to record the pressure and temperature inside the supercritical CO2 preparation device 3 and the pictures collected by the high-speed camera 15 in real time.

[0055] Example 2

[0056] A research method using the supercritical CO2 and associated gas dynamic mixing uniformity research system of Example 1, as shown in the figure, includes the following steps: Figure 2

[0057] Step 2: Connect the liquid CO2 Dewar flask 1 to the injection pump 2, and adjust the injection of liquid CO2 into the supercritical CO2 preparation device 3 through the valve and the pump setting, which needs to be controlled in combination with the CO2 phase diagram. The CO2 phase diagram is shown in the figure. Use the injection pump to inject liquid CO2 from the liquid CO2 storage device into the supercritical CO2 preparation device, control the temperature to make the liquid CO2 into dense phase CO2, and then make it into supercritical CO2 by heating. Figure 3

[0058] Specifically, the temperature inside the supercritical CO2 preparation device 3 is controlled by the electric heat tracing device. Under the premise that the temperature is lower than the CO2 gas-liquid phase transition temperature, liquid CO2 is injected into the supercritical CO2 preparation device, the hydraulic oil in the hydraulic oil supply system enters the bottom of the piston to push the piston to move to realize pressure control, and the pressure is set to 6 MPa. Through the piston to control the pressure, the electric heat tracing device controls the temperature to ensure that the CO2 liquid inside the supercritical CO2 preparation device is in a liquid phase, until the piston is pushed to the bottom of the supercritical CO2 preparation device, and the internal space volume of the supercritical CO2 preparation device reaches the maximum. Thereafter, continue to inject liquid CO2 into the supercritical CO2 preparation device to continuously increase the pressure inside the supercritical CO2 preparation device, while preventing the overpressure of the vaporization of liquid CO2, until the critical pressure is exceeded, and the liquid CO2 is converted into dense phase CO2. After the injection is completed, the temperature control is realized by the electric heat tracing device, and the heating is performed to make the dense phase CO2 into supercritical CO2. At the same time, the supercritical CO2 preparation device 3 is equipped with a safety valve 6 for safety control, and pressure relief is necessary.

[0059] The filling process is at a constant pressure of 6 MPa, accompanied by the movement of the piston and the injection of liquid CO2, until the piston is pushed to the bottom, and the internal space volume of the supercritical CO2 preparation device 3 reaches the maximum. This process is defined as a constant pressure filling process. Thereafter, the continuous pressure increase inside the supercritical CO2 preparation device 3 is controlled by monitoring the mass of the injected liquid CO2 until the critical pressure of 7.38 MPa is exceeded, and the liquid CO2 becomes dense phase CO2. This process can be defined as a constant volume pressure increasing process. In the constant pressure filling process, the injection rate of liquid CO2 does not need to be controlled, and the pressure is controlled by the piston.

[0060] ​​Step 3, the supercritical CO2 prepared in the supercritical CO2 preparation device 3 is mixed with the methane from the CNG bottle 5 which is decompressed by the second decompression valve 10 through the tee 11 after being decompressed by the first decompression valve 9, and then is injected into the high-pressure resistant pipeline 12 which is sealed at both ends. The mixing process needs to keep the first decompression valve 9 and the second decompression valve 10 open at the same time and the opening degree is controllable (referring to the opening degree coefficient of the decompression valve, controllable, adjustable), and the injection rate of the supercritical CO2 and the methane into the high-pressure resistant pipeline is uniform.

[0061] Step 4, after coming out of the tee 11, the mixture enters the high-pressure resistant pipeline 12 to develop fully, and after the supercritical CO2 and the associated gas mixture enter the high-pressure resistant pipeline to flow stably, the methane concentration at different positions is detected by the laser methane remote meter 14 through the transparent high-pressure view window 13 at different positions, and the methane concentration at different positions is recorded.

[0062] Step 5, after the supercritical CO2 and the associated gas mixture enter the high-pressure resistant pipeline 12 to flow stably, the mixing and layering of the supercritical CO2 and the associated gas mixture are observed directly through the high-pressure view window 13 or by using the high-speed camera 15.

[0063] Step 6, by adjusting the opening degree of the output valve 17 at the rear of the high-pressure resistant pipeline 12, different flow rates are controlled, the methane concentration at different positions under different flow rates is obtained, and the dynamic mixing of the supercritical CO2 and the methane mixture under different flow rates is analyzed.

[0064] Step 7, after the dynamic mixing of the supercritical CO2 and the methane mixture under different flow rates at a certain pipe diameter is tested, the high-pressure resistant pipeline 12 with different diameters is replaced, and the test is performed again to obtain the dynamic mixing of the supercritical CO2 and the associated gas mixture under different pipe diameters.

[0065] Step 8, the sensitivity of the variables affecting the dynamic mixing of the supercritical CO2 and the associated gas mixture is analyzed, including the pipe diameter and the flow rate, and the optimal variable combination of the dynamic mixing of the supercritical CO2 and the associated gas mixture is obtained.

[0066] The above only describes the preferred embodiments of the present application and is not used to limit the present application. For those skilled in the art, the present application can have various changes and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application shall be included in the protection scope of the present application.

Claims

1. A system for studying the dynamic mixing uniformity of supercritical carbon dioxide and associated gas, characterized in that, include: The fluid supply unit includes a liquid CO2 storage device and an injection pump connected in sequence, for injecting liquid carbon dioxide into the supercritical carbon dioxide preparation unit; The supercritical CO2 preparation unit includes a hydraulic oil supply system, a piston, a supercritical CO2 generator, and a first pressure reducing valve connected in sequence, which are used to prepare liquid carbon dioxide into supercritical carbon dioxide and transport it to the blending and development unit. The associated gas injection unit includes an oilfield associated gas storage device and a second pressure reducing valve connected in sequence, which are used to inject oilfield associated gas into the blending and development unit. The blending development unit includes a high-pressure resistant pipe sealed at both ends and a high-pressure resistant window. The high-pressure resistant window is set on the wall of the high-pressure resistant pipe and is used for dynamic blending of supercritical carbon dioxide and associated gas from the oil field. The detection unit includes an oilfield associated gas concentration detection device and a high-speed camera installed outside the high-pressure resistant pipeline. It is used to detect the concentration of oilfield associated gas at this location through the high-pressure resistant window and to observe the mixing and stratification of the mixture of supercritical CO2 and oilfield associated gas. The supercritical CO2 generator is equipped with an electric heat tracing and insulation device along its inner wall. The electric heat tracing and insulation device includes a heating resistor, a temperature sensor, and a pressure sensor. The piston is located inside the supercritical CO2 generator, and its cross-section matches the cross-section inside the supercritical CO2 generator. The piston can move horizontally inside the supercritical CO2 generator. By moving the piston, the size of the internal space of the supercritical CO2 generator is controlled, thereby controlling the internal pressure of the supercritical CO2 generator. The hydraulic oil in the hydraulic oil supply system enters the bottom of the piston and pushes the piston to move. The supercritical carbon dioxide output from the supercritical CO2 preparation unit and the associated gas from the oilfield output from the associated gas injection unit are mixed through a three-way valve before entering the blending development unit. The tee is installed on the pipeline between the first pressure reducing valve and the blending development unit; The blending development unit also includes an output valve for outputting a mixture of supercritical CO2 and associated gas from the oil field.

2. The system for studying the dynamic mixing uniformity of supercritical carbon dioxide and associated gas as described in claim 1, characterized in that, The supercritical CO2 generator is provided with a cement foundation at its bottom.

3. The system for studying the dynamic mixing uniformity of supercritical carbon dioxide and associated gas as described in claim 1, characterized in that, The supercritical CO2 generator is equipped with a safety valve.

4. The system for studying the dynamic mixing uniformity of supercritical carbon dioxide and associated gas as described in claim 1, characterized in that, Three sets of opposing high-pressure resistant viewing windows are installed at different positions at the same horizontal height on both sides of the high-pressure resistant pipeline, with two windows in each set, for visual observation, high-speed camera image acquisition, and component analysis.

5. The system for studying the dynamic mixing uniformity of supercritical carbon dioxide and associated gas as described in claim 1, characterized in that, The associated gas concentration detection equipment in the oilfield is a laser methane telemetry instrument.

6. A research method using the supercritical carbon dioxide and associated gas dynamic mixing uniformity research system described in any one of claims 1-5, characterized in that, Includes the following steps: Step 1: Use an injection pump to inject liquid CO2 from the liquid CO2 storage device into the supercritical CO2 generator, control the temperature to convert the liquid CO2 into dense phase CO2, and then increase the temperature to convert it into supercritical CO2. Step 2: The supercritical CO2 from the supercritical CO2 generator is mixed with methane from the associated gas storage unit of the oil field after passing through the first pressure reducing valve and the second pressure reducing valve. The mixture is then injected into a high-pressure resistant pipeline sealed at both ends. Step 3: After the supercritical CO2 and associated gas mixture enters the high-pressure resistant pipeline and flows stably, the methane concentration at each location is detected by a laser methane telemetry instrument through a transparent high-pressure resistant window at different locations, and the methane concentration at each location is recorded. Step 4: After the mixture of supercritical CO2 and associated gas enters the high-pressure resistant pipeline and flows stably, observe it directly through the high-pressure resistant viewing window or use a high-speed camera to observe the mixing and stratification of the mixture of supercritical CO2 and associated gas. Step 5: Different flow rates are controlled by the output valve at the end of the high-pressure pipeline to obtain the methane concentration at different locations under different flow rates, and to analyze the dynamic mixing of supercritical CO2 and associated gas mixture under different flow rates. Step 6: After the dynamic mixing of supercritical CO2 and associated gas mixture under a certain pipe diameter and different flow rates is tested, replace the high-pressure resistant pipes of different diameters and retest to obtain the dynamic mixing of supercritical CO2 and associated gas mixture under different pipe diameters. Step 7: Perform sensitivity analysis on the variables affecting the dynamic blending of supercritical CO2 and associated gas mixture to obtain the optimal combination of variables for dynamic blending of supercritical CO2 and associated gas mixture.

7. The research method as described in claim 6, characterized in that, In step 1, the process of supercritical CO2 preparation needs to be controlled in conjunction with the CO2 phase diagram; Liquid CO2 is injected into the supercritical CO2 generator. Hydraulic oil from the hydraulic oil supply system enters the bottom of the piston, pushing it to move and achieving pressure control. The pressure is set at 6 MPa. The piston controls the pressure, and an electric heating and insulation device controls the temperature to ensure that the CO2 inside the supercritical CO2 generator remains in the liquid phase until the piston is pushed to the bottom of the supercritical CO2 generator, reaching its maximum volume. Afterward, liquid CO2 is continuously injected into the supercritical CO2 generator, causing the internal pressure to rise continuously until it exceeds the critical pressure, at which point the liquid CO2 transforms into dense-phase CO2. After injection is complete, the temperature is increased, causing the dense-phase CO2 to transform into supercritical CO2.

8. The research method as described in claim 6, characterized in that, In step 2, when supercritical CO2 is mixed with associated gas from the oil field, the first and second pressure reducing valves open simultaneously and their opening degrees are controllable, and the injection rate of supercritical CO2 and associated gas from the oil field into the high-pressure resistant pipeline is uniform.

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