Experimental system and experimental method for simulating coal rock in high-temperature and high-pressure soaking environment

Abstract

The invention provides an experimental system and an experimental method for simulating a coal rock in a high-temperature and high-pressure soaking environment, and belongs to the field of coal rock physical property research. According to the system, accurate simulation of coal rock under the high-temperature and high-pressure fracturing fluid soaking condition is achieved through cooperation of multiple systems. The gas supply area regulates and controls the proportion of mixed gas through a gas mixing container, a flow controller and a concentration sensor, and ensures stable pressure in combination with a gas booster pump and a pressure stabilizing valve; the soaking area adopts a high-temperature-resistant and high-pressure-resistant reaction kettle and is arranged in a constant-temperature water bath box, and a formation temperature field is accurately simulated; the injection area pumps fracturing fluid and solution through an ISCO pump at a stable low flow rate, and the intermediate reaction container is matched to adjust the chemical properties of the fracturing fluid in real time so as to solve the problem of multi-phase flow coupling deficiency of a traditional experiment system, and a reliable experiment platform is provided for studying coal rock pore structure evolution, seepage characteristics and fracturing fluid-coal rock interaction. The method has important scientific value and application potential for optimizing the coal bed gas exploitation process.

Description

Technical Field

[0001] The present invention specifically relates to an experimental system and an experimental method for simulating the immersion of coal rock in a high-temperature and high-pressure environment, and belongs to the field of research on the physical properties of coal rock. Background Art

[0002] With the continuous development and utilization of shallow coal and oil and gas resources, their reserves are decreasing, and deep areas have become an important prospecting area in my country in the future. Coal rock pores are key sites for coalbed methane storage and enrichment, and are also the main space for carbon dioxide enhanced coalbed methane extraction and geological storage. Their structural characteristics and development patterns play a vital role in the exploration and development of deep energy. The efficiency of coalbed methane extraction in my country is closely related to factors such as the permeability of the coal seam, reservoir pressure, temperature, and the choice of fracturing fluid. The complex pore structure of the reservoir shows strong heterogeneity and low permeability. In addition, the traditional coal rock immersion experimental system has technical limitations, making it difficult to conduct accurate simulation experiments under high temperature and high pressure environments. For example, there is a lack of multiphase flow coupling: the liquid / gas injection system operates independently, and there is a lack of a multi-field coupling control mechanism. Therefore, the study of coal rock simulated high temperature and high pressure immersion environment is one of the important means to reveal the physical and chemical changes under the complex multi-field coupling during coal seam fracturing.

[0003] To optimize coalbed methane (CBM) extraction processes and improve efficiency, it is necessary to simulate the high-temperature, high-pressure immersion environment of coal rock under laboratory conditions to study the interaction between fracturing fluid and the coal seam and its impact on coal seam permeability. Therefore, given the limitations of traditional experimental systems and the urgent need for deep CBM extraction, an experimental system was developed that accurately simulates the high-temperature, high-pressure immersion environment of coal rock and features multiphase flow coupling control. This system takes into account the precise control of parameters such as surrounding rock pressure, temperature, gas occurrence, and fracturing fluid, and further explores the physical and chemical changes in coal rock under complex multi-field coupling, thereby revealing the interaction mechanism between fracturing fluid and coal seams. Summary of the Invention

[0004] The main technical problem solved by the present invention is to provide a device that can simulate the high-temperature and high-pressure immersion environment of coal rock. Under laboratory conditions, it can accurately simulate the actual immersion state of fracturing fluid under high-temperature and high-pressure conditions of coal rock, thereby effectively evaluating the impact of the fracturing fluid medium on the stability and permeability of coal rock, and then optimizing the fluid formula and process parameters in the coalbed methane extraction process, thereby improving the efficiency and safety of coalbed methane extraction.

[0005] In order to achieve the above object, the present invention is implemented through the following technical solutions.

[0006] An experimental system for simulating a high-temperature and high-pressure immersion environment of coal rock includes: a beaker, an ISCO pump, an intermediate reaction vessel, a control panel, a constant-temperature water bath, a vacuum pump, a first gas booster pump, a second gas booster pump, a computer, a high-pressure reactor, pipelines, gas cylinders (gas, nitrogen, carbon dioxide), helium cylinders, a gas mixing container, a gas concentration sensor, a gas flow sensor, a gas pressure regulating valve, and a gas pressure gauge.

[0007] The beaker is configured on an ISCO pump and connected to the ISCO pump through a hose. The beaker is filled with water for extraction by the ISCO pump.

[0008] The ISCO pump is connected to the beaker and the intermediate reaction vessel through a hose, which can achieve constant pressure or constant flow function and has a very stable pulse-free flow. It can simulate the high temperature and high pressure environment of coal rock and pump the solution at a stable rate. The ISCO pump can pump the solution in the beaker into the intermediate reaction vessel to adjust the chemical properties of the fracturing fluid. After the chemical properties of the fracturing fluid are adjusted, the solution in the intermediate reaction vessel can be pumped into the high-pressure reactor.

[0009] The intermediate reaction vessel is arranged between the ISCO pump and the high-pressure reactor and is started and stopped by the control panel. The intermediate reaction vessel is equipped with fracturing fluid and is equipped with a concentration sensor to adjust the chemical properties of the fracturing fluid in real time.

[0010] The control panel, the control ends of the first gas booster pump, the second gas booster pump, the vacuum pump, and the ISCO pump are all integrated on the control panel. The control panel is also electrically connected to the computer. The vacuum pump vacuuming, the fracturing fluid in the intermediate reaction vessel, and the switches of the gas cylinder gas inlet and outlet devices are all controlled by the control panel.

[0011] The constant temperature water bath can heat the high-pressure reactor. Four high-pressure reactors can be placed in the constant temperature water bath for experiments at the same time to simulate the formation temperature field with small temperature fluctuations. The temperature of the constant temperature water bath can be set according to the experimental requirements through the button in the lower right corner.

[0012] The vacuum pump is arranged at the high-pressure reactor. The vacuum pump vacuum level parameters are set by the computer and then started and stopped by the control panel to realize the vacuum pump vacuuming the high-pressure reactor.

[0013] The gas booster pumps are located between the helium cylinder and the autoclave, and between the gas mixing container and the autoclave. The gas pressure parameters of the gas booster pumps are set via a computer, and their start and stop are controlled via a control panel. Helium is supplied from the helium cylinder to the gas booster pump, which then passes through a gas pressure-stabilizing valve to create a certain pressure, and is then injected into the autoclave via the control panel. The mixed gas is then supplied from the gas mixing container to a second gas booster pump, which then passes through a gas pressure-stabilizing valve to create a certain pressure, and is then injected into the autoclave via the control panel.

[0014] The computer can set the vacuum degree, fracturing fluid injection volume, mixed gas injection volume and injected helium gas pressure value for the high-pressure reactor.

[0015] The high-pressure reactor is arranged in the water bath and is made of a high-temperature resistant alloy material. It is resistant to high pressure and high temperature. The high-pressure reactor serves as a pressurized container for soaking coal rocks.

[0016] Pipelines: The extraction and injection of liquids and gases between the various devices in this device are transported through pipelines.

[0017] The gas cylinder (gas, nitrogen, carbon dioxide) is connected to the gas mixing container through a pipeline. The gas cylinder supplies gas to the gas mixing container. The gas cylinder can be replaced with other gas type cylinders according to experimental needs.

[0018] The helium cylinder is connected to the gas booster pump through a pipeline, and the helium cylinder supplies gas to the gas booster pump.

[0019] The gas mixing container is placed between the gas cylinder (gas, nitrogen, carbon dioxide) and the control panel. The gases are mixed in it to obtain the mixed concentration of each gas required for the experiment.

[0020] The gas concentration sensor is arranged inside the gas mixing container and can monitor the concentration of each gas in the mixed gas.

[0021] The gas flow sensor is arranged on the pipeline between the gas cylinder and the gas mixing container. It senses the gas concentration through the gas concentration sensor in the gas mixing container and feeds it back to the flow controller to control the gas flow in real time to achieve the ideal mixed gas concentration.

[0022] The gas pressure stabilizing valves are respectively arranged on one side of the gas booster pump 20 and the gas booster pump 22. The gas pressure stabilizing valves stabilize the gas pressure to ensure that the gas pressure remains near the set value during transportation and use.

[0023] The gas pressure gauge is arranged on the high-pressure reactor. The gas pressure gauge can check the gas pressure value in the reactor in real time.

[0024] The present invention also provides an experimental method for simulating coal rock immersion in a high-temperature and high-pressure environment using the experimental system, and the specific steps are as follows:

[0025] Step 1. Open the high-pressure reactor, place the processed coal rock core into the reactor, and then close the reactor. The gas pressure gauge on the high-pressure reactor provides real-time feedback on the internal gas pressure. Heat the water in a constant-temperature water bath and control the temperature to simulate the formation temperature field.

[0026] Step 2. Open the intermediate reaction vessel, add the fracturing fluid required for the experiment into the intermediate reaction vessel, add purified water into the beaker, and use an ISCO pump to pump the solution in the beaker into the intermediate reaction vessel to adjust the chemical properties of the fracturing fluid. After the chemical properties of the fracturing fluid are adjusted, pump the solution in the intermediate reaction vessel into the high-pressure reactor;

[0027] Step 3. Start the computer and set the vacuum degree, fracturing fluid injection volume, mixed gas injection volume, and injected helium gas pressure according to the experimental requirements;

[0028] Step 4. Turn on the vacuum pump switch on the control panel to evacuate the high-pressure reactor through the vacuum pump;

[0029] Step 5. After the vacuum pump is completed, immediately turn off the vacuum pump switch on the control panel, turn on the fracturing fluid injection switch on the control panel, and use the ISCO pump to transport the prepared fracturing fluid in the intermediate reaction vessel into the high-pressure reactor;

[0030] Step 6. After the fracturing fluid is injected into the high-pressure reactor, immediately turn off the fracturing fluid injection switch on the control panel, then open the valves of the gas cylinder, nitrogen cylinder, and carbon dioxide cylinder to allow the gas to enter the gas mixing container and mix to obtain the required concentration of gas;

[0031] Step 7. Turn on the mixed gas injection and gas booster pump switches on the control panel. Then, the three mixed gases are pressurized and injected into the high-pressure reactor from the gas mixing container through the second gas booster pump to simulate the gas distribution of the coal rock sample in the coal seam;

[0032] Step 8. After the mixed gas injection into the autoclave is completed, immediately turn off the mixed gas injection switch on the control panel, unscrew the helium cylinder valve, and turn on the gas booster pump switch on the control panel to allow helium with a certain pressure to be pressed into the autoclave to simulate the original coal reservoir pressure in the autoclave;

[0033] Step 9. After the coal rock sample in the high-pressure reactor is soaked for the number of days required by the experiment, the high-pressure reactor is depressurized and the coal rock sample is taken out.

[0034] Compared with the prior art, the present invention has the following advantages and technical effects:

[0035] By installing an ISCO pump in the experimental system, combined with a beaker for water extraction, the present invention can stably simulate the high-temperature, high-pressure environment of coal rock, allowing for the stable pumping of corrosive solutions at a low flow rate. An intermediate reaction vessel, located between the ISCO pump and the autoclave, is equipped with a concentration sensor that allows real-time adjustment of the chemical properties of the fracturing fluid. A control panel connects components such as the gas mixing vessel, computer, vacuum pump, ISCO pump, and gas booster pump, and controls the autoclave, achieving unified control over the operation of each component and the delivery of media. Heating in a constant-temperature water bath accurately simulates formation temperature fields. The vacuum pump can be started and stopped via the control panel to evacuate the autoclave according to the vacuum level set by the computer. A gas pressure regulator ensures stable gas pressure. The gas booster pump, controlled via the control panel, draws gas from a helium cylinder and, after adjustment by the gas pressure regulator, injects helium at a specific pressure into the autoclave. The computer allows comprehensive control of key parameters such as the autoclave vacuum level, fracturing fluid injection volume, mixed gas injection volume, and helium injection pressure. The high-pressure reactor is made of high-temperature resistant alloy material with good pressure and temperature resistance, and is used as a pressurized container for coal rock immersion. The gas cylinder is connected to the gas mixing container, and the gas flow is controlled in real time by a flow sensor in conjunction with a gas concentration sensor to achieve the ideal mixed gas concentration. The present invention not only achieves accurate simulation of coal rock immersion in a high-temperature and high-pressure composite environment, making up for the lack of multiphase flow coupling in traditional devices, but also can accurately control various experimental parameters, monitor and adjust experimental conditions in real time, and the experimental conditions are highly adaptable, which can provide strong support for optimizing coalbed methane extraction technology and significantly improve the comprehensiveness, accuracy and practical application value of experimental research. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] Figure 1 Schematic diagram of the experimental system;

[0037] Figure 2 It is a structural diagram of the gas supply area;

[0038] Figure 3 It is a structural diagram of the immersion zone;

[0039] Figure 4 Schematic diagram of the structure of the injection area;

[0040] In the figure: 1-helium cylinder, 2-gas cylinder, 3-nitrogen cylinder, 4-carbon dioxide cylinder, 5-pipeline, 6-flow controller, 7-gas mixing container, 8-gas concentration sensor, 9-gas flow sensor, 10-gas pressure regulating valve, 11-control panel, 12-high pressure reactor, 13-gas pressure gauge, 14-constant temperature water bath, 15-intermediate reaction container, 16-ISCO pump, 17-beaker, 18-vacuum pump, 19-computer, 20-first gas booster pump, 21-second gas pressure regulating valve, 22-second gas booster pump. DETAILED DESCRIPTION

[0041] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only 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 making creative efforts are within the scope of protection of the present invention.

[0042] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, the present invention is further described in detail below with reference to the accompanying drawings and specific embodiments.

[0043] Example 1

[0044] Reference Figure 1 This embodiment provides an experimental system for simulating a high-temperature and high-pressure immersion environment of coal rock. The experimental system includes a gas supply area, an immersion area, and an injection area.

[0045] A helium cylinder 1 is provided in the gas supply area, which is connected to a first gas booster pump 20 through a pipeline 5. A second gas pressure-stabilizing valve 21 is provided on the pipeline 5 corresponding to the first gas booster pump 20; a gas cylinder 2, a nitrogen cylinder 3 and a carbon dioxide cylinder 4 are respectively connected to a gas mixing container 7 through separate pipelines 5. A flow controller 6 is provided on the pipeline 5 between the gas mixing container 7 and the gas cylinders, and a gas concentration sensor 8 is provided in the gas mixing container 7. The gas concentration sensor 8 is used to feedback the concentration of each gas and adjust the flow controller 6, and then the gas flow sensor 9, the second gas booster pump 22 and the gas pressure-stabilizing valve 10 are used to supply the high-pressure reactor 12 with the required stable pressure and ratio of the mixed gas.

[0046] In the immersion area, the control ends of the first gas booster pump 20, the second gas booster pump 22, the vacuum pump 18, and the ISCO pump 16 are all integrated on the control panel 11. The control panel 11 is also electrically connected to the computer 19. The fracturing fluid injection amount, vacuum degree, gas pressure, and mixed gas injection amount can be set on the computer 19. The computer 19 controls the above parameters and components through the control panel 11. The high-pressure reactor 12 is provided with a gas pressure gauge 13 to display the pressure in real time. The high-pressure reactor 12 is placed in a constant temperature water bath 14. The constant temperature water bath 14 provides constant temperature heating to the high-pressure reactor 12 in a water bath to achieve accurate simulation of the formation temperature field.

[0047] An ISCO pump 16 is installed in the injection zone and is connected to a beaker 17 via a hose. It can pump the solution in beaker 17 and the intermediate reaction vessel 15 at a steady rate of 455t. The intermediate reaction vessel 15 is connected to the ISCO pump 16 via a pipe 5. The intermediate reaction vessel 15 is equipped with fracturing fluid and is equipped with a concentration sensor to adjust the chemical properties of the fracturing fluid in real time.

[0048] The ISCO pump 16 can pump the solution in the beaker 17 into the intermediate reaction vessel 15 to adjust the chemical properties of the fracturing fluid. After the chemical properties of the fracturing fluid are adjusted, the solution in the intermediate reaction vessel 15 can be pumped into the high-pressure reactor 12.

[0049] Example 2

[0050] This embodiment is based on the experimental system described in Example 1. The experimental system described in Example 1 is used to conduct an experiment simulating coal rock immersion in a high-temperature and high-pressure environment. The specific method is as follows:

[0051] Step 1. Open the high-pressure reactor 12, place the processed coal rock core into the high-pressure reactor 12 and then close it. The gas pressure gauge 13 on the high-pressure reactor 12 can provide real-time feedback on the internal gas pressure. Use a constant temperature water bath 14 to heat the water bath and control the temperature to simulate the formation temperature field.

[0052] Step 2. Open the intermediate reaction vessel 15, add the fracturing fluid required for the experiment into the intermediate reaction vessel 15, add pure water to the beaker 17, and use the ISCO pump 16 to pump the solution in the beaker 17 into the intermediate reaction vessel 15 to adjust the chemical properties of the fracturing fluid. After the chemical properties of the fracturing fluid are adjusted, pump the solution in the intermediate reaction vessel 15 into the high-pressure reactor 12 to achieve a stable rate by pumping the water in the beaker 17 and the fracturing fluid in the intermediate reaction vessel 15 through the ISCO pump 16.

[0053] Step 3. Start the computer 19, set the vacuum degree, fracturing fluid injection volume, mixed gas injection volume and injected helium gas pressure value according to the experimental requirements, and send a control signal to the control panel (11) through the computer (19).

[0054] Step 4: Turn on the vacuum pump switch on the control panel 11 to evacuate the high-pressure reactor 12 via the vacuum pump 18 .

[0055] Step 5. After the vacuum pump 18 completes the vacuum operation, immediately turn off the vacuum pump switch on the control panel 11 and turn on the fracturing fluid injection switch on the control panel 11 to pump the prepared fracturing fluid in the intermediate reaction vessel 15 into the high-pressure reactor 12 via the ISCO pump 16 .

[0056] Step 6. After the fracturing fluid is injected into the high-pressure reactor 12, the fracturing fluid injection switch on the control panel 11 is immediately turned off, and then the valves of the gas cylinder 2, nitrogen cylinder 3 and carbon dioxide cylinder 4 are unscrewed to allow the gas to enter the gas mixing container 7 and be mixed to obtain the required concentration of gas.

[0057] Step 7. Turn on the mixed gas injection and gas booster pump switches on the control panel 11, and then the three mixed gases are pressurized and injected into the high-pressure reactor 12 from the gas mixing container 7 through the second gas booster pump 22 to simulate the gas storage conditions of the coal rock sample in the coal seam.

[0058] Step 8. Once the mixed gas injection into the autoclave 12 is complete, immediately turn off the mixed gas injection switch on the control panel 11. Unscrew the valve on the helium cylinder 1 and turn on the gas booster switch on the control panel 11 to allow helium gas under pressure to enter the autoclave 12, simulating the original coal reservoir pressure in the autoclave 12.

[0059] Step 9. After the coal rock sample in the high-pressure reactor 12 is soaked for the number of days required by the experiment, the high-pressure reactor 12 is depressurized and the coal rock sample is taken out.

[0060] Example 2

[0061] The difference between this embodiment and embodiment 1 is that in this embodiment, the pipelines 5 connected to the high-pressure reactor 12 are all supplied to the high-pressure reactor 12 after passing through the control panel 11, and each pipeline 5 passing through the control panel 11 is provided with an electric control valve, and the control end of the electric control valve is provided on the control panel 11, so that the opening and closing of each pipeline 5 supplying the high-pressure reactor 12 can be simultaneously controlled by the control panel 11.

[0062] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. An experimental system for simulating high-temperature and high-pressure immersion of coal rock, characterized by: It includes gas supply area, soaking area and injection area; In the gas supply area, the helium cylinder (1) is connected to the high-pressure reactor (12) through a pipeline (5), and a first gas booster pump (20) is provided on the pipeline (5). The gas cylinder (2), the nitrogen cylinder (3) and the carbon dioxide cylinder (4) are respectively connected to the gas mixing container (7) through another pipeline (5). After being mixed in the gas mixing container (7), the gas is connected to the high-pressure reactor (12) through a separate pipeline (5). A second gas booster pump (22) is provided on the separate pipeline (5). The vacuum pump (18) is also connected to the high-pressure reactor (12) through a separate pipeline (5); In the soaking zone, the high-pressure reactor (12) is arranged in a constant-temperature water bath (14); In the injection zone, an ISCO pump (16) is connected to the high-pressure reactor (12) via a pipeline (5) through an intermediate reaction vessel (15), and a liquid supply pipe of the ISCO pump (16) is located in a beaker (17) for supplying liquid to the ISCO pump (16); The control terminals of the first gas booster pump (20), the second gas booster pump (22), the vacuum pump (18), and the ISCO pump (16) are all integrated on a control panel (11), and the control panel (11) is also electrically connected to a computer (19).

2. The experimental system according to claim 1, characterized in that: In the gas supply area, a flow controller (6) is provided on the pipeline (5) between the gas cylinder (2), the nitrogen cylinder (3), the carbon dioxide cylinder (4) and the gas mixing container (7), and a gas concentration sensor (8) is provided inside the gas mixing container (7).

3. The experimental system according to claim 1, characterized in that: A gas flow sensor (9) and a gas pressure stabilizing valve (10) are provided on the pipeline (5) between the gas mixing container (7) and the high-pressure reactor (12).

4. The experimental system according to claim 1, characterized in that: In the gas supply area, a second gas pressure stabilizing valve (21) is provided between the first gas booster pump (20) and the high-pressure reactor (12).

5. The experimental system according to claim 1, characterized in that: In the soaking zone, a gas pressure gauge (13) is provided on the high-pressure reactor (12).

6. An experimental method for simulating coal rock immersion in a high-temperature and high-pressure environment using the experimental system described in any one of claims 1 to 5, characterized in that: The specific steps are as follows: Step 1. Open the high-pressure reactor (12), place the processed coal rock core into the high-pressure reactor (12), and then close it. The gas pressure gauge (13) on the high-pressure reactor (12) provides real-time feedback of the internal gas pressure. A constant-temperature water bath (14) is used to heat the water and control the temperature to simulate the formation temperature field. Step 2. Open the intermediate reaction vessel (15), add the fracturing fluid required for the experiment into the intermediate reaction vessel (15), add purified water into the beaker (17), and use the ISCO pump (16) to pump the solution in the beaker (17) into the intermediate reaction vessel (15) to adjust the chemical properties of the fracturing fluid. After the chemical properties of the fracturing fluid are adjusted, the solution in the intermediate reaction vessel (15) is pumped into the high-pressure reactor (12); Step 3. Start the computer (19) and set the vacuum degree, fracturing fluid injection volume, mixed gas injection volume and injected helium gas pressure value according to the experimental requirements; Step 4. Controlling the vacuum pump (18) through the control panel (11) to evacuate the high-pressure reactor (12); Step 5. After the vacuum pump (18) is completed, the vacuum pump (18) is immediately turned off, and the fracturing fluid injection switch on the control panel (11) is turned on to pump the prepared fracturing fluid in the intermediate reaction vessel (15) through the ISCO pump (16) and inject it into the high-pressure reactor (12); Step 6. After the fracturing fluid is injected into the high-pressure reactor (12), the fracturing fluid injection switch on the control panel (11) is immediately turned off, and then the valves of the gas cylinder (2), nitrogen cylinder (3) and carbon dioxide cylinder (4) are opened to allow the gases to enter the gas mixing container (7) and be mixed to obtain the desired concentration of gas; Step 7. Turn on the mixed gas injection and gas booster pump switches on the control panel (11), and then the three mixed gases are pressurized and injected into the high-pressure reactor (12) from the gas mixing container (7) through the gas booster pump (22) to simulate the gas distribution of the coal rock sample in the coal seam; Step 8. After the mixed gas injection operation of the high-pressure reactor (12) is completed, the mixed gas injection switch on the control panel (11) is immediately closed, the valve of the helium cylinder (1) is unscrewed, and the gas booster switch on the control panel (11) is turned on to allow helium with a certain pressure to be pressed into the high-pressure reactor (12), so that the high-pressure reactor (12) simulates the original reservoir pressure of the coal rock; Step 9. After the coal rock sample in the high-pressure reactor (12) is soaked for the number of days required by the experiment, the high-pressure reactor (12) is depressurized and the coal rock sample is taken out.

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