Simulation experiment device and method for action of coal rock and carbon dioxide at high temperature and high pressure

Abstract

The invention belongs to the technical field of carbon dioxide geological sequestration, and relates to a simulation experiment device and method for coal rock and carbon dioxide action under high temperature and high pressure. Comprising a data acquisition and processing system, a high-temperature circulation control system, a high-pressure pumping system and a coal-rock reaction test system, the coal rock reaction test system comprises a reaction kettle, a coal rock sample, a uniaxial compression instrument arranged in the reaction kettle, and a pressure and temperature sensor for monitoring the temperature and pressure of the environment where the coal rock sample is located in real time; the high-temperature circulation control system is used for controlling and monitoring the reaction temperature in a reaction kettle in the coal rock reaction test system in real time; the high-pressure pumping system is used for controlling and monitoring the pressure in a reaction kettle in the coal rock reaction test system in real time; and the data acquisition and processing system is used for acquiring, processing, displaying and storing experimental data in real time. According to the invention, coal rock and carbon dioxide action underground in-situ condition simulation and mechanical property testing in a non-pressure-relief in-situ state are realized.

Description

Technical Field

[0001] The present invention belongs to the technical field of geological storage of carbon dioxide, and in particular relates to a device and method for simulating an experimental reaction between coal rock and carbon dioxide under high temperature and high pressure. Background Art

[0002] The geological storage and utilization of carbon dioxide is an important technical means to alleviate global warming. The closed structures that can be used for geological storage of carbon dioxide mainly include depleted oil and gas layers, deep saline water layers and deep unminable coal seams. Among them, the technology of injecting carbon dioxide into coal seams to displace coalbed methane has broad application prospects. Deep unminable coal seams have great storage potential: on the one hand, the coal body is an organic rock with a developed organic structure and has the characteristics of spontaneous adsorption of fluids; on the other hand, the deep surrounding rock structure makes it difficult for gas to overflow, increasing storage stability. Coalbed methane is a type of clean energy found in coal seams. This technology uses the principle of competitive adsorption of carbon dioxide and coalbed methane in coal to achieve effective geological storage of carbon dioxide, while also improving the extraction efficiency of coalbed methane.

[0003] Large coal-consuming factories such as thermal power plants and chemical plants are also large sources of carbon dioxide emissions. They are generally built near major coal-producing areas in order to save energy and transportation costs. This also reduces the transportation cost of carbon dioxide by sealing it in nearby coal seams.

[0004] In the process of injecting carbon dioxide into coal seams to extract coalbed methane and long-term geological storage, the changes in coal seam strength and deformation have become a crucial research topic. When carbon dioxide is injected into deep coal seams, when the local temperature and pressure exceed the critical point (31.1℃, 7.38MPa), carbon dioxide will naturally become a supercritical state. In this special state, carbon dioxide will have a viscosity and diffusion coefficient similar to that of gas and a density and solubility of liquid, and has extraordinary physical and chemical activity. Therefore, it is necessary to carry out research on the interaction between coal rock and carbon dioxide under high temperature and high pressure, clarify the relevant adsorption process of carbon dioxide on coal rock, the degradation of mechanical properties of coal rock and the evolution of permeability, so as to provide important theoretical support for the long-term geological storage of carbon dioxide in deep coal seams.

[0005] Traditional mechanical tests on the interaction between coal and carbon dioxide under high temperature and high pressure are mostly carried out by unloading the pressure after the reaction is completed and taking it to an exposed environment for testing, ignoring the impact of environmental changes caused by unloading on the experimental results. Unloading the pressure will cause the release of the internal stress field of the coal and rock samples, resulting in a rebound effect. Some cracks formed by pressure loads may close after unloading the pressure. After unloading the pressure, carbon dioxide is converted into gas, which may cause the adsorbed carbon dioxide to desorb, destroying the dynamic balance of the original adsorption behavior. Summary of the invention

[0006] In view of the above technical problems, the present invention provides a device and method for simulating the reaction of coal rock and carbon dioxide under high temperature and high pressure. The device provided by the present invention can simulate the underground in-situ conditions of the reaction of coal rock and carbon dioxide and test the mechanical properties under the non-depressurized in-situ state, providing theoretical and technical support for the long-term geological storage of carbon dioxide in deep coal seams.

[0007] In order to achieve the above technical objectives, the present invention provides the following technical solutions: A simulation experimental device for the reaction of coal rock and carbon dioxide under high temperature and high pressure, comprising: a data acquisition and processing system, a high temperature circulation control system, a high pressure pump injection system and a coal rock reaction test system; The coal-rock reaction test system includes a reactor, a coal-rock sample placed inside the reactor, a uniaxial compression instrument arranged in the reactor for applying pressure to the coal-rock sample, and a pressure-temperature sensor for real-time monitoring of the temperature and pressure of the environment in which the coal-rock sample is located; The high temperature cycle control system is used to monitor and control the reaction temperature in the reactor of the coal-rock reaction test system in real time; The high-pressure pumping system is used to monitor and control the pressure in the reactor of the coal-rock reaction test system in real time; The data acquisition and processing system is connected to the uniaxial compression instrument and pressure and temperature sensor in the coal-rock reaction test system, and is used to control the uniaxial compression instrument, and to collect, process, display and store the experimental data obtained by the uniaxial compression instrument and the pressure and temperature sensor in real time.

[0008] Furthermore, in the coal-rock reaction testing system, the reactor comprises a reactor body and an outer cover of the reactor body; the coal-rock sample is arranged in a closed cavity formed by the reactor body and the outer cover of the reactor body.

[0009] Furthermore, the uniaxial compression instrument is fixedly arranged below the outer cover of the kettle body, and a gasket is arranged between the uniaxial compression instrument and the coal rock sample.

[0010] Further, the high temperature circulation control system includes a temperature controller, a heating circulator, a ring heating furnace and a reflux heating pipeline; The annular heating furnace is arranged around the periphery and bottom of the reactor body, and the inner net size of the annular heating furnace is matched with the outer size of the reactor; The temperature controller is connected to the heating circulator, and the heating circulator is connected to the annular heating furnace through the reflux heating pipeline; The temperature controller is used to control the heating circulator to generate hot liquid, and the hot liquid flows to the annular heating furnace outside the reaction kettle through the reflux heating pipe.

[0011] Furthermore, the high temperature circulation control system controls the temperature in the reactor by controlling the fluid volume in the annular heating furnace and the external circulation flow rate; The volume of the hot liquid fluid is controlled to be 5-8 L and the external circulation flow rate is controlled to be 8-10 L / min; the temperature in the reactor is controlled to be between room temperature and 300°C.

[0012] Furthermore, the high-pressure pumping system includes a gas cylinder, an air compressor, a booster pump and a water source; The gas cylinder, the air compressor, and the water source are all connected to the booster pump, and a pressure control valve is connected between the gas cylinder and the booster pump; the air compressor is used to provide pressure to the booster pump; The output end of the booster pump is connected to the air inlet of the reactor to apply high-pressure carbon dioxide gas to the reactor. By controlling the high-pressure pumping system, the pressure in the reactor is controlled at 7.3MPa-20MPa.

[0013] Furthermore, the data acquisition and processing system includes a computer and a data transmission line; the computer includes a uniaxial compression instrument control module, a data acquisition module and a data processing module; The computer is connected to the pressure and temperature sensor and the uniaxial compression instrument via the data transmission line; The uniaxial compression instrument control module is used to control the opening and closing of the uniaxial compression instrument and to control the magnitude of the pressure applied by the uniaxial compression instrument to the sample; The data acquisition module is used to observe, collect and display the experimental data of the pressure and temperature sensor and the uniaxial compression instrument in real time; The data processing module is used for processing, exporting and storing experimental data.

[0014] A method for simulating the effect of coal rock and carbon dioxide under high temperature and high pressure, the method comprising the following steps: (1) Place the sample in the reactor, place the gasket on top of the sample, and install the outer cover of the reactor with the uniaxial compression instrument fixed; (2) Turn on the high-temperature circulation control system, and the hot liquid flows to the annular heating furnace outside the reactor through the reflux heating pipe to heat the reactor, so that the reactor containing the coal and rock samples simulates the underground in-situ temperature conditions; After the temperature of the reactor reaches the preset temperature, the temperature is continuously monitored for at least half an hour. When the temperature in the reactor no longer changes, the process proceeds to step (3) to perform a pressurization test. (3) After the temperature is raised, turn on the gas cylinder, booster pump and air compressor to apply high-pressure carbon dioxide gas to the reactor; raise the pressure of carbon dioxide in the reactor to above 7.38 MPa to reach a supercritical state; (4) Gradually increase the pressure in the reactor to the set pressure, stop the air intake, and check the air tightness of the device; After the temperature and pressure have reached the preset values ​​and have not changed for more than half an hour, the temperature and pressure in the reactor are observed and adjusted at least once every 24 hours to keep the temperature and pressure in the reactor at the set values; after the coal and rock samples have been retained at the set temperature and pressure conditions for a set time, step (5) is entered; (5) Turn on the uniaxial compression instrument, set the loading rate on the computer to 0.5-1 MPa / s, load the coal and rock until the sample is destroyed, then stop loading and remove the load on the sample; (6) After the mechanical test is completed, the experimental data is exported. According to the temperature, pressure, time, and deformation values ​​recorded by the data acquisition and processing system, the temperature and pressure value versus time curves and the stress-strain curves are plotted. The data are stored and exported for post-processing data analysis.

[0015] Furthermore, the method further comprises the following steps: (7) Pressure relief and cooling: Open the air release valve of the reactor, alternately unload the pressure to 0 MPa, symmetrically loosen the fastening bolts on the reactor, and take the coal and rock samples out of the high-pressure reactor after they have cooled down. Observe the appearance of the coal and rock samples, take photos of the surface of the coal and rock samples, observe the cracks in the coal and rock samples, and record, describe and analyze the characteristics of the induced cracks in detail; (8) End of the experiment: After completing the interaction between supercritical carbon dioxide and coal rock samples under the set parameter conditions of an experiment, repeat steps (1) to (6) to conduct the next set parameter experiment; after all experiments are completed, turn off all power supplies, discharge the gas in the air compressor, ensure that there is no residual high-pressure gas in the pipeline, discharge the gas in the air compressor, and end the experiment.

[0016] The beneficial effects of the present invention are: Aiming at realizing the laboratory simulation of the high-temperature and high-pressure carbon dioxide reaction under real coal rock underground in-situ conditions, the present invention constructs a data acquisition and processing system, a high-temperature circulation control system, a high-pressure pump injection system and a coal rock reaction test system; realizes the reaction experiment of high-temperature and high-pressure carbon dioxide and coal rock under different conditions in the underground in-situ state, and real-time monitoring, recording and quantitative analysis of the injection pressure and coal rock temperature are carried out, and the control, monitoring and export and storage of experimental data of all experiments are realized by setting up the data acquisition and processing system, the real-time control and monitoring of hydrothermal heating are realized by setting up the high-temperature circulation control system, the real-time control and monitoring of carbon dioxide injected under different conditions are realized by setting up the high-pressure pump injection system, and the underground in-situ state of coal rock is reproduced by setting up the coal rock reaction test system, and mechanical testing is carried out under non-depressurization conditions, so as to avoid the influence of the depressurization process and the environmental changes after depressurization on the mechanical properties of coal rock, and the mechanical properties of coal rock under the action of in-situ carbon dioxide are more accurately obtained, so as to provide theoretical and technical support for the long-term geological storage of carbon dioxide in deep coal seams.

[0017] The device provided by the present invention is cheap, occupies a small area, and has a convenient and safe operation method and low resource consumption. It can simulate the in-situ state of actual coal rock reservoirs, accurately measure data, and has strong engineering practicability. It is a practical in-situ high temperature and high pressure simulation experimental device and experimental method for coal rock and carbon dioxide interaction simulation. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 It is a structural schematic diagram of a simulation experimental device for the action of coal rock and carbon dioxide under high temperature and high pressure disclosed by the present invention; Figure 2 It is a schematic flow chart of a simulation experimental method for the reaction of coal rock and carbon dioxide under high temperature and high pressure disclosed in the present invention; Explanation of the accompanying drawings: 1. Data acquisition and processing system; 2. High-temperature circulation control system; 3. High-pressure pumping system; 4. Coal-rock reaction test system; 5. Computer; 6. Data transmission line; 7. Temperature controller; 8. Heating circulator; 9. Ring heating furnace; 10. Reflux heating pipeline; 11. Gas cylinder; 12. Air compressor; 13. Booster pump; 14. Water source; 15. Pressure control valve; 16. Reactor body; 17. Reactor body outer cover; 18. Pressure and temperature sensor; 19. Coal-rock sample; 20. Fastening bolts; 21. Nuts; 22. Inlet valve; 23. Exhaust valve; 24-1. Servo hydraulic test cylinder; 24-2. Force sensor; 24-3. Displacement sensor; 25. Gasket. DETAILED DESCRIPTION

[0019] In order to make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. 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 technicians in this field without creative work are within the scope of protection of the present invention.

[0020] Therefore, the following detailed description of the embodiments of the present invention provided in the accompanying drawings is not intended to limit the scope of the invention claimed for protection, but merely represents selected embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0021] Example 1: A simulation experimental device for the reaction between coal rock and carbon dioxide under high temperature and high pressure, as shown in the attached Figure 1 As shown, it includes: data acquisition and processing system, high temperature circulation control system, high pressure pump injection system and coal-rock reaction test system; The coal-rock reaction test system includes a reactor, a coal-rock sample placed inside the reactor, a uniaxial compression instrument arranged in the reactor for applying pressure to the coal-rock sample, and a pressure-temperature sensor for real-time monitoring of the temperature and pressure of the environment in which the coal-rock sample is located; The high temperature cycle control system is used to control and monitor the reaction temperature in the reactor in the coal-rock reaction test system in real time; The high-pressure pumping system is used to control and monitor the pressure in the reactor of the coal-rock reaction test system in real time; The data acquisition and processing system is connected to the uniaxial compression instrument and pressure and temperature sensor in the coal-rock reaction test system, and is used for real-time acquisition, processing, display and storage of experimental data obtained by the uniaxial compression instrument and pressure and temperature sensor.

[0022] In the coal-rock reaction test system described in this embodiment, the reactor comprises a reactor body and a reactor body cover; The coal and rock samples are arranged in a closed cavity formed by the reactor body and the reactor body outer cover.

[0023] Specifically, the outer cover of the kettle body is arranged on the top of the reactor body, a fastening bolt is arranged on the outer cover of the kettle body, and a reserved hole is arranged on the top of the reactor body; the fastening bolt passes through the reserved hole and is fastened and connected with a nut; the reactor body and the outer cover of the kettle body are connected through the fastening bolt, the reserved hole and the nut; An air inlet and an air outlet are arranged on the outer cover of the kettle body, and an air inlet valve and an air outlet valve are arranged on the air inlet and the air outlet; A pressure and temperature sensor is installed on the outer cover of the reactor body, and the collection end of the pressure and temperature sensor extends into the reactor through the outer cover of the reactor body. The output end of the pressure and temperature sensor is electrically connected to the computer in the data collection and processing system.

[0024] In this embodiment, the uniaxial compression instrument is fixedly arranged below the outer cover of the kettle body, and a gasket is arranged between the uniaxial compression instrument and the coal rock sample. Specifically, the gasket is used to make the sample evenly stressed and is made of 316L stainless steel.

[0025] Specifically, the magnitude of the pressure applied by the uniaxial compression instrument to the sample is set by the data acquisition and processing system; the uniaxial compression instrument consists of a loading device, a stress measuring device and a displacement measuring device: the loading device adopts a PZ-d1000 / 600 servo hydraulic test cylinder for axial loading of the sample, the displacement measuring device adopts an HBM WA 200 displacement sensor with a measuring range of ±200mm; the stress measuring device adopts an HBM C18 force sensor with a measuring range of ±1000 kN for measurement.

[0026] In this embodiment, the high temperature circulation control system includes a temperature controller, a heating circulator, a ring heating furnace and a reflux heating pipeline; The annular heating furnace is arranged around the periphery and bottom of the reactor body, and the inner net size of the annular heating furnace is matched with the outer size of the reactor; The temperature controller is connected to the heating circulator, and the heating circulator is connected to the annular heating furnace through the reflux heating pipeline; The temperature controller is used to control the heating circulator to generate hot liquid, and the hot liquid flows to the annular heating furnace outside the reaction kettle through the reflux heating pipe.

[0027] In this embodiment, the high temperature circulation control system controls the temperature in the reactor by controlling the fluid volume in the annular heating furnace and the external circulation flow rate; By controlling the volume of the hot liquid fluid to 5L and the external circulation flow rate to 8L / min; In this embodiment, the high-pressure pumping system includes a gas cylinder, an air compressor, a booster pump and a water source; The gas cylinder, the air compressor and the water source are all connected to the booster pump, and a pressure control valve is connected between the gas cylinder and the booster pump; the air compressor is used to provide pressure to the booster pump; wherein, the water source is opened when used for multi-fluid experiments, and is closed if there are no other fluids in the designed experiment.

[0028] The output end of the booster pump is connected to the air inlet of the reactor to apply high-pressure carbon dioxide gas to the reactor.

[0029] In this embodiment, the data acquisition and processing system includes a computer and a data transmission line; the computer includes a uniaxial compression instrument control module, a data acquisition module and a data processing module; The computer is connected to the pressure and temperature sensor and the uniaxial compression instrument via the data transmission line; The uniaxial compression instrument control module is used to control the opening and closing of the uniaxial compression instrument and to control the magnitude of the pressure applied by the uniaxial compression instrument to the sample; The data acquisition module is used to observe, collect and display the experimental data of the pressure and temperature sensor and the uniaxial compression instrument in real time; The data processing module is used for processing, exporting and storing experimental data.

[0030] Example 2: A simulation experimental method for the reaction between coal rock and carbon dioxide under high temperature and high pressure, referring to the attached Figure 2 As shown, the method comprises the following steps: (1) Experimental preparation: Place the sample in the reactor, place the gasket on top of the sample, and install the outer cover of the reactor with the uniaxial compression instrument fixed; check the connection between the instruments, and after confirming that they are correct, connect the power supply of each device. Connect the experimental equipment and check the air tightness; place the sample in the reactor, place the gasket on top of the sample, install the outer cover of the reactor, and tighten the screws diagonally in turn. The torque wrench is considered to meet the requirements when it is 90-100N·m. Turn on the data acquisition and processing system and start collecting time, temperature, pressure and other data in the experiment; (2) Sample heating: Turn on the high-temperature circulation control system, and the hot liquid flows through the reflux heating pipe to the annular heating furnace outside the reactor to heat the reactor, so that the reactor containing the coal and rock samples can simulate the underground in-situ temperature conditions; After the temperature of the reactor reaches the preset temperature, the temperature is continuously monitored for at least half an hour. When the temperature in the reactor no longer changes, the process proceeds to step (3) to perform a pressurization test. Among them, the high-temperature circulation control system is turned on to start heating the reactor, so that the reactor containing the coal and rock samples can simulate the underground in-situ temperature conditions; the data acquisition module is connected to the pressure and temperature sensor to monitor the real-time experimental conditions of the reactor; the data acquisition module transmits the detection data to the data processing module, and the data processing module records all experimental data; (3) Sample pressurization: After the temperature is raised, turn on the gas cylinder, booster pump and air compressor to apply high-pressure carbon dioxide gas to the reactor; raise the pressure of carbon dioxide in the reactor to above 7.38 MPa to reach a supercritical state (the pressure should be appropriately higher during the experiment to prevent the pressure from dropping to the critical value due to the reaction of carbon dioxide); (4) Adjustment and stability: gradually increase the pressure in the reactor to the set pressure, stop the air intake, and check the air tightness of the device; Keep the temperature and pressure at the preset values ​​and do not change for more than half an hour (wherein, since the temperature of the reactor will further increase during the pressurization process, it is necessary to adjust the temperature controller in this step to reach the preset value), and then observe and adjust the temperature and pressure in the reactor at least once every 24 hours to keep the temperature and pressure in the reactor at the set values; after the coal and rock samples are retained at the set temperature and pressure conditions for the set time, proceed to step (5); (5) Mechanical test: Turn on the uniaxial compression instrument, set the loading rate to 0.5 MPa / s on the computer, load the coal and rock until the sample is destroyed, then stop loading and remove the load on the sample; (6) Exporting data: After the mechanical test is completed, the experimental data is exported. According to the temperature, pressure, time, and deformation values ​​recorded by the data acquisition and processing system (obtained through the displacement sensor in the uniaxial compression instrument), the temperature value and pressure value versus time curves and the stress-strain curve are plotted. The data are stored and exported for post-processing data analysis.

[0031] (7) Pressure relief and cooling: Slowly open the air release valve of the reactor, alternately unload the pressure to 0 MPa, symmetrically loosen the fastening bolts on the reactor, and take the coal and rock samples out of the high-pressure reactor after they have cooled down. Observe the appearance of the coal and rock samples, take photos of the surface of the coal and rock samples, observe the cracks in the coal and rock samples, and record, describe and analyze the characteristics of the induced cracks in detail; (8) End of the experiment: After completing the interaction between supercritical carbon dioxide and coal rock samples under the set parameter conditions of an experiment, repeat steps (1) to (6) to conduct the next set parameter experiment; after all experiments are completed, turn off all power supplies, discharge the gas in the air compressor, ensure that there is no residual high-pressure gas in the pipeline, discharge the gas in the air compressor, and end the experiment.

[0032] The following is a specific embodiment: a simulation experiment of the interaction between supercritical carbon dioxide and coal rock was carried out. The coal rock sample was a coal sample from a coal mine. The sample was processed into a 50mm×100mm cylindrical sample by a cutting machine; the two ends of the cylindrical sample were ground on a grinding machine. After grinding, the non-parallelism of the two end surfaces of the sample was no more than 0.05mm, and the axial deviation was no more than 0.25°.

[0033] The experiment is divided into the interaction reaction between supercritical carbon dioxide and coal at different temperatures and the interaction reaction between supercritical carbon dioxide and coal at different reaction times.

[0034] In order to study the effect of temperature change on the interaction between supercritical carbon dioxide and coal, multiple supercritical carbon dioxide and coal interaction experiments were carried out at 40℃, 50℃ and 60℃. The differences in various properties of coal and the adsorption laws of supercritical carbon dioxide at different temperatures were compared and analyzed.

[0035] In order to study the effect of reaction time on the interaction between supercritical carbon dioxide and coal, multiple supercritical carbon dioxide and coal interaction experiments were carried out under 4 days, 8 days, and 12 days, and a group of liquid carbon dioxide and coal interaction experiments under the same time were used as the control group. The differences in various properties of supercritical carbon dioxide acting on coal and the adsorption laws under different reaction times were compared and analyzed.

[0036] The specific experimental steps of using the high temperature and high pressure coal-carbon dioxide interaction simulation experimental device to conduct supercritical carbon dioxide and coal interaction experiments at different temperatures and reaction times are as follows: Check the connection between each instrument, and after confirming that it is correct, connect the power supply of each device. Connect the experimental equipment and check the airtightness; put the sample into the reactor, place the gasket on the top of the sample, install the outer cover of the reactor, tighten the screws diagonally in turn, and the torque wrench is considered to meet the requirements at 90-100N·m, turn on the data acquisition and processing system, and start collecting time, temperature, pressure and other data in the experiment.

[0037] (2) Turn on the temperature controller, and the hot liquid circulates in the annular heating furnace to heat the reactor. After the temperature of the reactor reaches the preset temperature, observe for half an hour. When the temperature no longer changes, perform a pressurization test.

[0038] (3) After the temperature is raised, turn on the gas cylinder and the air compressor to increase the pressure of carbon dioxide to above 7.38 MPa, so that it reaches a supercritical state (the pressure is slightly higher during the experiment to prevent the pressure from dropping to the critical value due to the reaction of carbon dioxide).

[0039] (4) Gradually increase the pressure to the set pressure, close the air compressor and the reactor air inlet valve, and check the air tightness of the device again. Since the reactor temperature will rise further during the pressurization process, it is necessary to adjust the temperature controller again to reach the preset value, keep the temperature and pressure at the preset value and keep them unchanged for more than half an hour, and then observe the temperature and pressure at least once every 24 hours to keep them at the set value.

[0040] (5) After the coal rock sample has been kept under the set conditions for the set time, the uniaxial compression instrument is turned on, and the loading rate is set to 0.5 MPa / s on the computer to load the coal rock. After the sample is destroyed, the loading is stopped and the load is unloaded.

[0041] (6) After the mechanical test is completed, the experimental data is exported. According to the temperature, pressure, time, and deformation values ​​recorded by the data acquisition and processing system, the temperature and pressure value versus time curves and the stress-strain curves are plotted. The data are stored and exported for post-processing data analysis.

[0042] (7) Slowly open the reactor vent valve, alternately unload the pressure to 0 MPa, symmetrically loosen the reactor screws, and carefully remove the sample from the high-pressure reactor after the sample has cooled down. Observe the appearance of the coal sample, take photos of its surface, observe the cracks in the sample, and record, describe and analyze the characteristics of the induced cracks in detail.

[0043] (8) After completing the interaction between supercritical carbon dioxide and coal under the set parameters of one experiment, repeat steps 1 to 6 to conduct the next set parameter experiment. After all experiments are completed, turn off all system power supplies, exhaust the gas in the air compressor, ensure that there is no residual high-pressure gas in the pipeline, exhaust the gas in the air compressor, and end the experiment.

[0044] The mass of coal samples before and after the reaction was measured, and it was found that after being acted upon by supercritical carbon dioxide, most of the coal samples showed a slight decrease in mass during measurement, with an average mass reduction of about 1.5%. This proves that supercritical carbon dioxide has fully reacted with coal rock. Under high temperature and high pressure conditions, the volatility of volatile substances increases, and the moisture and other volatile components after the reaction in the coal are more easily desorbed and volatilized and mixed or dissolved in the supercritical carbon dioxide. They are then carried out of the reactor during the final pressure release process, resulting in a reduction in the mass of the coal.

[0045] It should be noted that the specific models and specifications of the data acquisition and processing system, temperature controller, heating circulator, reflux heating pipe, gas cylinder, air compressor, booster pump, gas pipeline, pressure control valve, reactor, reactor body outer cover, pressure and temperature sensor, fastening bolts, air inlet, air outlet, etc. in the present invention need to be selected and determined according to the actual specifications of the device, and the specific selection and calculation method adopts the existing technology in the field, so it will not be described in detail.

[0046] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A simulation experimental device for the effect of coal rock and carbon dioxide under high temperature and high pressure, characterized in that: include: Data acquisition and processing system, high temperature circulation control system, high pressure pump injection system and coal-rock reaction test system; The coal-rock reaction test system includes a reactor, a coal-rock sample placed inside the reactor, a uniaxial compression instrument arranged in the reactor for applying pressure to the coal-rock sample, and a pressure-temperature sensor for real-time monitoring of the temperature and pressure of the environment in which the coal-rock sample is located; The high temperature cycle control system includes an annular heating furnace arranged around the reactor body and the bottom, and the high temperature cycle control system is used to monitor and control the reaction temperature in the reactor in the coal-rock reaction test system in real time; The high-pressure pumping system includes a booster pump connected to the air inlet of the reactor, and the high-pressure pumping system is used to monitor and control the pressure in the reactor of the coal-rock reaction test system in real time; The data acquisition and processing system is connected to the uniaxial compression instrument and pressure and temperature sensor in the coal-rock reaction test system, and is used to control the uniaxial compression instrument, and to collect, process, display and store the experimental data obtained by the uniaxial compression instrument and the pressure and temperature sensor in real time.

2. According to the high temperature and high pressure experimental device for simulating the effect of coal rock and carbon dioxide on the carbon dioxide, the device is characterized in that: In the coal-rock reaction testing system, the reactor comprises a reactor body and an outer cover of the reactor body; the coal-rock sample is arranged in a closed cavity formed by the reactor body and the outer cover of the reactor body.

3. According to the high temperature and high pressure experimental device for simulating the effect of coal rock and carbon dioxide, the device is characterized in that: The uniaxial compression instrument is fixedly arranged below the outer cover of the kettle body, and a gasket is arranged between the uniaxial compression instrument and the coal rock sample.

4. The experimental device for simulating the effect of coal rock and carbon dioxide under high temperature and high pressure according to claim 1, characterized in that: The high temperature circulation control system includes a temperature controller, a heating circulator, a ring heating furnace and a reflux heating pipeline; The annular heating furnace is arranged around the periphery and bottom of the reactor body, and the inner net size of the annular heating furnace is matched with the outer size of the reactor; The temperature controller is connected to the heating circulator, and the heating circulator is connected to the annular heating furnace through the reflux heating pipeline; The temperature controller is used to control the heating circulator to generate hot liquid, and the hot liquid flows to the annular heating furnace outside the reaction kettle through the reflux heating pipe.

5. The experimental device for simulating the effect of coal rock and carbon dioxide under high temperature and high pressure according to claim 4, characterized in that: The high temperature circulation control system controls the temperature in the reactor by controlling the fluid volume in the annular heating furnace and the external circulation flow rate; The volume of the hot liquid fluid is controlled to be 5-8 L and the external circulation flow rate is controlled to be 8-10 L / min; the temperature in the reactor is controlled to be between room temperature and 300°C.

6. The experimental device for simulating the effect of coal rock and carbon dioxide under high temperature and high pressure according to claim 1, characterized in that: The high-pressure pumping system includes a gas cylinder, an air compressor, a booster pump and a water source; The gas cylinder, the air compressor, and the water source are all connected to the booster pump, and a pressure control valve is connected between the gas cylinder and the booster pump; the air compressor is used to provide pressure to the booster pump; The output end of the booster pump is connected to the air inlet of the reactor to apply high-pressure carbon dioxide gas to the reactor. By controlling the high-pressure pumping system, the pressure in the reactor is controlled at 7.3MPa-20MPa.

7. The experimental device for simulating the effect of coal rock and carbon dioxide under high temperature and high pressure according to claim 1, characterized in that: The data acquisition and processing system includes a computer and a data transmission line; the computer includes a uniaxial compression instrument control module, a data acquisition module and a data processing module; The computer is connected to the pressure and temperature sensor and the uniaxial compression instrument via the data transmission line; The uniaxial compression instrument control module is used to control the opening and closing of the uniaxial compression instrument and to control the magnitude of the pressure applied by the uniaxial compression instrument to the sample; The data acquisition module is used to observe, collect and display the experimental data of the pressure and temperature sensor and the uniaxial compression instrument in real time; The data processing module is used for processing, exporting and storing experimental data.

8. A method for simulating the reaction of coal rock and carbon dioxide under high temperature and high pressure, characterized in that: The method comprises the following steps: (1) Place the sample in the reactor, place the gasket on top of the sample, and install the outer cover of the reactor with the uniaxial compression instrument fixed; (2) Turn on the high-temperature circulation control system, and the hot liquid flows through the reflux heating pipe to the annular heating furnace outside the reactor to heat the reactor, so that the reactor containing the coal and rock samples can simulate the underground in-situ temperature conditions; After the temperature of the reactor reaches the preset temperature, the temperature is continuously monitored for at least half an hour. When the temperature in the reactor no longer changes, the process proceeds to step (3) to perform a pressurization test. (3) After the temperature is raised, turn on the gas cylinder, booster pump and air compressor to apply high-pressure carbon dioxide gas to the reactor; raise the pressure of carbon dioxide in the reactor to above 7.38 MPa to reach a supercritical state; (4) Gradually increase the pressure in the reactor to the set pressure, stop the air intake, and check the air tightness of the device; After the temperature and pressure have reached the preset values ​​and have not changed for more than half an hour, the temperature and pressure in the reactor are observed and adjusted at least once every 24 hours to keep the temperature and pressure in the reactor at the set values; after the coal and rock samples have been retained at the set temperature and pressure conditions for a set time, step (5) is entered; (5) Turn on the uniaxial compression instrument, set the loading rate on the computer to 0.5-1 MPa / s, load the coal and rock until the sample is destroyed, then stop loading and remove the load on the sample; (6) After the mechanical test is completed, the experimental data is exported. According to the temperature, pressure, time, and deformation values ​​recorded by the data acquisition and processing system, the temperature and pressure value versus time curves and the stress-strain curves are plotted. The data are stored and exported for post-processing data analysis.

9. The method for simulating the reaction of coal rock and carbon dioxide under high temperature and high pressure according to claim 8, characterized in that: The method further comprises the following steps: (7) Pressure relief and cooling: Open the air release valve of the reactor, alternately unload the pressure to 0 MPa, symmetrically loosen the fastening bolts on the reactor, and take the coal and rock samples out of the high-pressure reactor after they have cooled down. Observe the appearance of the coal and rock samples, take photos of the surface of the coal and rock samples, observe the cracks in the coal and rock samples, and record, describe and analyze the characteristics of the induced cracks in detail; (8) End of the experiment: After completing the interaction between supercritical carbon dioxide and coal rock samples under the set parameter conditions of an experiment, repeat steps (1) to (6) to conduct the next set parameter experiment; after all experiments are completed, turn off all power supplies, discharge the gas in the air compressor, ensure that there is no residual high-pressure gas in the pipeline, discharge the gas in the air compressor, and end the experiment.

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