Nuclear magnetic resonance based coal sample multifunctional testing device

Abstract

The utility model discloses a coal sample multifunctional testing device based on nuclear magnetic resonance, including computer, gas cylinder subassembly, nuclear magnetic support platform, coal sample holder, stable displacement pump and laser transmitter, and the left end import of gas cylinder subassembly is connected with coal sample holder, and coal sample holder is established on nuclear magnetic support platform, and the sapphire window is established on coal sample holder, and the laser of laser transmitter is emitted to the sapphire window observation coal sample holder in the cylindrical coal sample, and the right end export of coal sample holder is connected with test pipeline, and coal sample holder is connected with the surrounding pressure control pipeline. The utility model principle science applies advanced technology such as nuclear magnetic resonance, laser scanning to coalbed gas reservoir free gas content simulation experiment, and the data of testing is more accurate. The utility model function is various, can carry out permeameter test, methane adsorption experiment, gas displacement experiment etc.

Description

Technical Field

[0001] This utility model belongs to the field of coal seam free gas testing technology, specifically relating to a multifunctional coal sample testing device based on nuclear magnetic resonance. Background Technology

[0002] Nuclear magnetic resonance (NMR) technology is widely used in oil and gas exploration and coalbed methane development for rock property analysis and gas occurrence state detection. Traditional NMR testing methods are typically limited to static or non-visual experimental conditions, making it difficult to observe the dynamic changes in gas adsorption, desorption, and displacement processes in coal seams (coalbed methane reservoirs) under high temperature and pressure conditions in real time and intuitively. Furthermore, existing free gas content calculation models often neglect the coupled effects of multiple factors such as geostress, temperature, adsorption expansion effects, and pore compressibility, leading to significant deviations between calculated results and actual layer conditions. This is especially true in deep coal seams, where high geostress and high temperature environments have a more significant impact on coal and rock pore structure and gas occurrence state, making it difficult for traditional methods to accurately reflect the free gas content under real geological conditions. Therefore, developing a real-time, visually monitorable NMR device and a method for correcting free gas content in coal seams has become a pressing technical problem in this field. Utility Model Content

[0003] This invention overcomes the shortcomings of the prior art and provides a multifunctional coal sample testing device based on nuclear magnetic resonance that can perform real-time visual monitoring, multi-physics field coupling experiments and dynamic monitoring, and more accurately measure the free gas content under real geological conditions.

[0004] To solve the above-mentioned technical problems, the present invention adopts the following technical solution: a multifunctional coal sample testing device based on nuclear magnetic resonance, including a computer 49, a gas cylinder assembly, a nuclear magnetic resonance platform 17, a coal sample holder 16, a stable displacement pump 44, and a laser emitter 20. The gas cylinder assembly is connected to the left inlet of the coal sample holder 16 through a conventional injection pipeline A4. The coal sample holder 16 is mounted on the nuclear magnetic resonance platform 17 and has a sapphire window 45. The laser emitted by the laser emitter 20 observes the cylindrical coal sample inside the coal sample holder 16 through the sapphire window 45. The right outlet of the coal sample holder 16 is connected to a test pipeline A5. The coal sample holder 16 is connected to a confining pressure control pipeline A6. The stable displacement pump 44 is connected to the conventional injection pipeline A4 adjacent to the left inlet of the coal sample holder 16 through a gas displacement pipeline A2. Data collected from each component and pipeline is transmitted to the computer 49 via a data cable.

[0005] The gas cylinder assembly includes a methane cylinder 101, a carbon dioxide cylinder 102, and a nitrogen cylinder 103 connected in parallel. The methane cylinder 101 is connected to the conventional injection pipeline A4 in sequence through the first cylinder valve 1 and the first pressure reducing valve 2. The carbon dioxide cylinder 102 is connected to the conventional injection pipeline A4 in sequence through the second cylinder valve 3 and the second pressure reducing valve 4. The nitrogen cylinder 103 is connected to the conventional injection pipeline A4 in sequence through the third cylinder valve 5 and the third pressure reducing valve 6. The conventional injection pipeline A4 is provided with a gas source main valve 7, a booster pump 8, a booster storage tank 9, a fourth pressure reducing valve 10, a two-position four-way valve 11, a switch needle valve 13, a four-way pipe joint 43, and an inlet pressure sensor 14 in sequence along the airflow direction. The third port of the two-position four-way valve 11 is connected to a waste vent valve 12. The fourth port of the two-position four-way valve 11 is connected to the third port of the four-way pipe connector 43. A vacuum line A3 is provided on the vacuum line A3 from the two-position four-way valve 11 to the four-way pipe connector 43, consisting of a vacuum pump 38, a methane gas receiving valve 39, a reference tank 40, and a methane gas output valve 42. A reference tank pressure sensor 41 is provided on the reference tank 40.

[0006] One end of the gas displacement pipeline A2 is connected to the fourth interface of the four-way pipe fitting 43; the stable displacement pump 44 is connected to the displacement main pipeline A7, the other end of the gas displacement pipeline A2 is connected to the displacement main pipeline A7, and a drain valve 31 is provided at the other end of the displacement main pipeline A7. The gas displacement pipeline A2 is provided with a power gas switch valve 30, a gas displacement storage tank 32, a first displacement gas switch valve 34, a three-way pipe joint 33, a gas heating container 35 and a displacement outlet valve 36 in sequence from the stable displacement pump 44 to the four-way pipe joint 43. The third port of the three-way pipe connector 33 is connected between the pressurized storage tank 9 and the fourth pressure reducing valve 10 of the conventional injection pipeline A4 through the displacement gas pipeline A1. The displacement gas pipeline A1 is equipped with a second displacement gas switch valve 37.

[0007] The coal sample holder 16 has a transparent rubber sleeve 46 for mounting cylindrical coal samples. The center line of the transparent rubber sleeve 46 is set in the left-right direction. The transparent rubber sleeve 46 has an annular confining pressure cavity inside. The left and right sides of the coal sample holder 16 are respectively provided with confining pressure liquid injection ports 47 that communicate with the annular confining pressure cavity. The left and right ends of the coal sample holder 16 are both sealed pipe joints 48. The sealed pipe joint 48 at the left end is connected to the conventional injection pipeline A4, and the sealed pipe joint 48 at the right end is connected to the test pipeline A5.

[0008] The confining pressure control pipeline A6 is provided with a left confining pressure loading connector 29, a preheater 21, a confining pressure controller 23 and a right confining pressure loading connector 19 from left to right. The left confining pressure loading connector 29 and the right confining pressure loading connector 19 are respectively connected to the confining pressure liquid injection ports 47 on the left and right sides. The preheater 21 is provided with a heating temperature sensor 22, the confining pressure controller 23 is provided with a confining pressure sensor 24, the confining pressure controller 23 is connected to a confining pressure liquid storage tank 25, and the coal sample holder 16 is provided with a coal sample temperature sensor 15 for real-time monitoring of the internal temperature of the transparent rubber sleeve 46.

[0009] The test pipeline A5 is equipped with an outlet pressure sensor 18, a back pressure valve 26, a gas measuring valve and a flow meter 28 from left to right. The back pressure valve 26 is connected to a manual pump 27 for adjusting the pressure of the back pressure valve.

[0010] By adopting the above technical solution, compared with the prior art, the present invention has the following technical effects: (1) This utility model sets a sapphire window on the coal sample holder to realize real-time visualization observation of the gas migration behavior inside the coal sample under high temperature and high pressure conditions; integrates a laser emitter for accurate measurement (observation of volume strain during coal sample adsorption / desorption process); and combines a nuclear magnetic resonance system (nuclear magnetic platform) to synchronously monitor the dynamic changes of adsorbed gas and free gas.

[0011] (2) This utility model can realize the coordinated control and monitoring of multiple parameters such as temperature, confining pressure, gas pressure, and adsorption strain; provide an integrated experimental process for adsorption, displacement, and permeability testing of various gases (such as CH4, CO2, and N2); support real-time nuclear magnetic scanning and flow monitoring of the CO2 displacement of methane process, and provide data support for the evaluation of gas displacement efficiency.

[0012] (3) The principle of this utility model is scientific. It applies advanced technologies such as nuclear magnetic resonance and laser scanning to the simulation experiment of free gas content in coalbed methane reservoirs, making the test data more accurate. This utility model has multiple functions, including permeability testing, methane adsorption experiments, gas displacement experiments, etc. The test results can be used to evaluate the distribution characteristics of free gas in geological media such as coal seams and shale, providing theoretical data support for my country's energy development. Attached Figure Description

[0013] Figure 1 This is a schematic diagram of the overall structure of this utility model; Figure 2 This is a perspective view of the nuclear magnetic support, laser emitter, and sapphire window coal sample holder in this utility model.

[0014] Reference numerals: 1-First gas cylinder valve, 2-First pressure reducing valve, 3-Second gas cylinder valve, 4-Second pressure reducing valve, 5-Third gas cylinder valve, 6-Third pressure reducing valve, 7-Main gas source valve, 8-Boosting pump, 9-Boosting storage tank, 10-Fourth pressure reducing valve, 11-Two-position four-way valve, 12-Waste gas vent valve, 13-Switch needle valve, 14-Inlet pressure sensor, 15-Coal sample temperature sensor, 16-Coal sample holder, 17-NMR support, 18-Outlet pressure sensor, 19-Right confining pressure loading connector, 20-Laser emitter, 21-Preheater, 22-Heating temperature sensor, 23-Confining pressure controller, 24-Confining pressure sensor, 25-Confining pressure liquid storage tank, 26-Back pressure valve, 27-Manual pump, 28-Flow meter, 29-Left confining pressure loading connector 30-Power gas switch valve, 31-Drain valve, 32-Gas displacement storage tank, 33-T-connector, 34-First displacement gas switch valve, 35-Gas heating container, 36-Displacement outlet valve, 37-Second displacement gas shut-off valve, 38-Vacuum pump, 39-Methane gas receiving valve, 40-Reference tank, 41-Reference tank pressure sensor, 42-Methane gas output valve, 43-Four-way pipe interface, 44-Stable displacement pump, 45-Sapphire window, 46-Transparent rubber sleeve, 47-Containing pressure liquid injection port, 48-Sealed pipe connector, 49-Computer, A1-Displacement gas pipeline, A2-Gas displacement pipeline, A3-Vacuum pumping pipeline, A4-Conventional injection pipeline, A5-Test pipeline, A6-Containing pressure control pipeline, A7-Displacement main pipeline. Detailed Implementation

[0015] like Figures 1-2 As shown, the multifunctional coal sample testing device based on nuclear magnetic resonance of this invention includes a computer 49, a gas cylinder assembly, a nuclear magnetic resonance platform 17, a coal sample holder 16, a stable displacement pump 44, and a laser emitter 20. The gas cylinder assembly is connected to the left inlet of the coal sample holder 16 via a conventional injection pipeline A4. The coal sample holder 16 is mounted on the nuclear magnetic resonance platform 17 and has a sapphire window 45. The laser emitted by the laser emitter 20 observes the cylindrical coal sample inside the coal sample holder 16 through the sapphire window 45. The right outlet of the coal sample holder 16 is connected to a test pipeline A5, and the coal sample holder 16 is connected to a confining pressure control pipeline A6. The stable displacement pump 44 is connected to the conventional injection pipeline A4 adjacent to the left inlet of the coal sample holder 16 via a gas displacement pipeline A2. Data collected from each component and pipeline is transmitted to the computer 49 via a data cable.

[0016] The gas cylinder assembly includes a methane cylinder 101, a carbon dioxide cylinder 102, and a nitrogen cylinder 103 connected in parallel. The methane cylinder 101 is connected to the conventional injection pipeline A4 in sequence through the first cylinder valve 1 and the first pressure reducing valve 2. The carbon dioxide cylinder 102 is connected to the conventional injection pipeline A4 in sequence through the second cylinder valve 3 and the second pressure reducing valve 4. The nitrogen cylinder 103 is connected to the conventional injection pipeline A4 in sequence through the third cylinder valve 5 and the third pressure reducing valve 6. The conventional injection pipeline A4 is provided with a gas source main valve 7, a booster pump 8, a booster storage tank 9, a fourth pressure reducing valve 10, a two-position four-way valve 11, a switch needle valve 13, a four-way pipe joint 43, and an inlet pressure sensor 14 in sequence along the airflow direction. The third port of the two-position four-way valve 11 is connected to a waste vent valve 12. The fourth port of the two-position four-way valve 11 is connected to the third port of the four-way pipe connector 43. A vacuum line A3 is provided on the vacuum line A3 from the two-position four-way valve 11 to the four-way pipe connector 43, consisting of a vacuum pump 38, a methane gas receiving valve 39, a reference tank 40, and a methane gas output valve 42. A reference tank pressure sensor 41 is provided on the reference tank 40.

[0017] One end of the gas displacement pipeline A2 is connected to the fourth interface of the four-way pipe fitting 43; the stable displacement pump 44 is connected to the displacement main pipeline A7, the other end of the gas displacement pipeline A2 is connected to the displacement main pipeline A7, and a drain valve 31 is provided at the other end of the displacement main pipeline A7. The gas displacement pipeline A2 is provided with a power gas switch valve 30, a gas displacement storage tank 32, a first displacement gas switch valve 34, a three-way pipe joint 33, a gas heating container 35 and a displacement outlet valve 36 in sequence from the stable displacement pump 44 to the four-way pipe joint 43. The third port of the three-way pipe connector 33 is connected between the pressurized storage tank 9 and the fourth pressure reducing valve 10 of the conventional injection pipeline A4 through the displacement gas pipeline A1. The displacement gas pipeline A1 is equipped with a second displacement gas switch valve 37.

[0018] The coal sample holder 16 has a transparent rubber sleeve 46 for mounting cylindrical coal samples. The center line of the transparent rubber sleeve 46 is set in the left-right direction. The transparent rubber sleeve 46 has an annular confining pressure cavity inside. The left and right sides of the coal sample holder 16 are respectively provided with confining pressure liquid injection ports 47 that communicate with the annular confining pressure cavity. The left and right ends of the coal sample holder 16 are both sealed pipe joints 48. The sealed pipe joint 48 at the left end is connected to the conventional injection pipeline A4, and the sealed pipe joint 48 at the right end is connected to the test pipeline A5.

[0019] The confining pressure control pipeline A6 is provided with a left confining pressure loading connector 29, a preheater 21, a confining pressure controller 23 and a right confining pressure loading connector 19 from left to right. The left confining pressure loading connector 29 and the right confining pressure loading connector 19 are respectively connected to the confining pressure liquid injection ports 47 on the left and right sides. The preheater 21 is provided with a heating temperature sensor 22, the confining pressure controller 23 is provided with a confining pressure sensor 24, the confining pressure controller 23 is connected to a confining pressure liquid storage tank 25, and the coal sample holder 16 is provided with a coal sample temperature sensor 15 for real-time monitoring of the internal temperature of the transparent rubber sleeve 46.

[0020] The test pipeline A5 is equipped with an outlet pressure sensor 18, a back pressure valve 26, a gas measuring valve and a flow meter 28 from left to right. The back pressure valve 26 is connected to a manual pump 27 for adjusting the pressure of the back pressure valve.

[0021] This invention is mainly used for permeability testing, methane adsorption experiments, and gas displacement experiments on coal samples. Details are as follows: Example 1: Permeability test, the specific process is as follows: The extracted cylindrical coal sample is placed into the coal sample holder 16 of this invention, and the airtightness of the pipeline of the nuclear magnetic resonance device is tested. The preheater 21 and confining pressure controller 23 are started, and confining pressure liquid is drawn from the confining pressure liquid storage tank 25. The preheater 21 heats the confining pressure liquid and then delivers it to the transparent rubber sleeve 46. After the transparent rubber sleeve 46 is filled with confining pressure liquid, circumferential pressure is applied to the outer circumference of the cylindrical coal sample. The coal sample temperature, confining pressure liquid heating temperature, and confining pressure are monitored in real time by the coal sample temperature sensor 15, heating temperature sensor 22, and confining pressure sensor 24, respectively. The third gas cylinder valve 5 and the third pressure reducing valve 6 are opened to connect the nitrogen gas source. The main gas source valve 7 is opened, and the booster pump 8 is started to inject nitrogen from the nitrogen cylinder 103 into the booster storage tank 9. Then, the waste vent valve 12 is closed, and the two... Rotate the four-way valve 11 to the position where the fourth pressure reducing valve 10 and the switch needle valve 13 are connected. Open the switch needle valve 13. Nitrogen gas in the pressurized storage tank 9 is injected into the left end of the coal sample in the coal sample holder through the conventional injection pipeline A4 after being depressurized by the fourth pressure reducing valve 10. Gas overflows from the right end of the coal sample under the applied confining pressure. Observe the readings of the inlet pressure sensor 14 and the outlet pressure sensor 18 to confirm whether the preset experimental gas pressure has been reached. After the gas pressure stabilizes at the target gas pressure, close the liquid measuring valve 50 and open the gas measuring valve. The flow meter 28 monitors the gas flow rate. The parameters monitored in real time are transmitted to the computer to determine the permeability of the coal sample under a certain confining pressure stress condition.

[0022] Example 2: Methane gas adsorption test, the specific process is as follows: Close the third cylinder valve 5 and the third pressure reducing valve 6, and disconnect the nitrogen cylinder 103; evacuate the pipeline and coal sample holder, close the waste vent valve 12, rotate the two-position four-way valve 11 to the position where the fourth pressure reducing valve 10 and vacuum pump 38 are connected, open the methane gas receiving valve 39 and the methane gas output valve 42, start the vacuum pump 38, and evacuate the connected pipeline. After the pressure of the vacuum pump 38 drops to negative pressure, close the vacuum pump 38 and the methane gas output valve 42; apply a constant effective stress to the coal sample through the confining pressure controller 23. This stress value should be equal to the in-situ effective stress of the coal sample. To simulate formation constraint conditions, the preheater 21 is activated to heat the confining fluid. The temperature monitored by the coal sample temperature sensor 15 is kept constant and determined as the reservoir temperature. The first gas cylinder valve 1 and the first pressure reducing valve 2 are opened to connect the methane gas source. The main gas source valve 7 is opened, and the booster pump 8 is started to inject the methane gas from the methane cylinder 101 into the booster storage tank 9, and the target gas pressure is set. The experimental gas pressure is further adjusted through the fourth pressure reducing valve 10, and the methane gas is injected into the reference tank 40. The gas pressure is confirmed to meet the set value by the reference tank pressure sensor 41 on the reference tank 40. Then, the back pressure is opened. Valve 26 is used to set the pressure of the back pressure valve 26 slightly higher than the experimental gas pressure to prevent gas escape. Finally, the methane gas output valve 42 is opened, and the methane gas in the reference tank 40 enters the coal sample injected into the left end of the coal sample in the coal sample holder 16. The methane gas enters the coal sample under confined pressure, and the adsorption experiment begins. During the adsorption experiment, the NMR platform 17 is activated to scan and monitor the dynamic changes of the adsorbed gas and free gas, and the adsorption expansion strain of the coal sample is monitored in real time through the sapphire window using the laser emitter 20. In the process of injecting methane gas into the coal sample, a staged injection of methane gas is adopted. The methane gas adsorption pressure is gradually increased from zero to the reservoir pressure, and full equilibrium is achieved at each pressure point. During each pressure equilibrium stage, the macroscopic expansion deformation, i.e., volumetric strain, of the coal sample in the visualization holder is first monitored using the laser emitter 20 to obtain its adsorption expansion amount. At the same time, the methane adsorption amount of the coal sample is measured in real time through the NMR platform 17. Under different adsorption pressures, the laser emitter 20 transmits the volumetric strain data and the NMR platform 17 transmits the methane adsorption amount data to the computer. Based on the various parameters collected in real time, the computer can calculate the adsorption expansion coefficient of the coal sample.

[0023] Example 3: Carbon dioxide displacement experiment, the specific process is as follows: First, close the first gas cylinder valve 1, the first pressure reducing valve 2, and the fourth pressure reducing valve 10. Open the second gas cylinder valve 3 and the second pressure reducing valve 4, turn on the carbon dioxide cylinder, open the main gas source valve 7, and start the booster pump 8 to inject CO2 into the booster tank 9 and set it to the target pressure. Then, open the first displacement gas switch valve 34, the second displacement pipe gas switch valve 37, the power gas switch valve 30, and the drain valve 31. The CO2 in the booster tank 9 is injected into the gas displacement tank 32, pushing the piston in the gas displacement tank 32 downwards. The displacement fluid below the piston in the gas displacement tank 32 is discharged through the power gas switch valve 30 and the drain valve 31. Observe continuously for 30 minutes, and close the drain valve 31 after confirming no liquid outflow. Next, according to the experimental requirements for the CO2 state, through the gas... The heating container 35 adjusts the system temperature. After the temperature stabilizes, the second displacement pipe gas switch valve 37 is closed, the stable displacement pump 44 is started, the displacement driving fluid is prepared, the required displacement pressure is set, and the displacement outlet valve 36 is opened to start the CO2 displacement process. The displacement driving fluid drives the piston to move upward in the gas displacement tank 32, pushing out the CO2 in the gas displacement tank 32 and injecting it into the left end of the coal sample in the coal sample holder 16 through the conventional injection pipeline A4. During the displacement process, the nuclear magnetic resonance platform 17 is used to perform real-time scanning to monitor the dynamic changes of adsorbed gas and free gas in the coal and rock. At the same time, the liquid measuring valve 50 is closed and the gas measuring valve is opened. The flow meter 28 records the gas flow rate changes during the displacement process. The nuclear magnetic resonance platform 17 and the flow meter 28 transmit the monitored data to the computer 49.

[0024] It should be emphasized that the gas cylinder assembly, NMR support 17, coal sample holder 16, stabilizing displacement pump 44, laser emitter 20, various valves, booster pump 8, booster storage tank 9, gas displacement storage tank 32, various temperature sensors, various pressure sensors, flow meter 28, and other components in this utility model are all existing technologies and commonly used laboratory equipment. Their specific structures and working principles will not be elaborated here. Furthermore, the automatic control and computer calculations involved in this utility model are based on conventional algorithms and do not involve new computer programs.

[0025] The above embodiments illustrate the basic principles and features of this utility model. However, the above descriptions are merely preferred embodiments and are not limited to these embodiments. Those skilled in the art, inspired by this patent, can make many modifications and improvements without departing from the spirit and scope of the claims, all of which fall within the protection scope of this utility model. Therefore, the patent and its scope of protection should be determined by the appended claims.

Claims

1. A multifunctional coal sample testing device based on nuclear magnetic resonance, characterized in that: The system includes a computer (49), a gas cylinder assembly, an NMR tectonic plate (17), a coal sample holder (16), a stable displacement pump (44), and a laser emitter (20). The gas cylinder assembly is connected to the left inlet of the coal sample holder (16) via a conventional injection line (A4). The coal sample holder (16) is mounted on the NMR tectonic plate (17) and has a sapphire window (45). The laser emitted by the laser emitter (20) passes through the sapphire window. (45) Observe the cylindrical coal sample in the coal sample holder (16). The right end outlet of the coal sample holder (16) is connected to the test pipeline (A5). The coal sample holder (16) is connected to the confining pressure control pipeline (A6). The stable displacement pump (44) is connected to the conventional injection pipeline (A4) at the left end inlet of the adjacent coal sample holder (16) through the gas displacement pipeline (A2). The data collected from each component and pipeline are transmitted to the computer (49) through the data line.

2. The multifunctional coal sample testing device based on nuclear magnetic resonance according to claim 1, characterized in that: The gas cylinder assembly includes a methane cylinder (101), a carbon dioxide cylinder (102), and a nitrogen cylinder (103) connected in parallel. The methane cylinder (101) is connected to the conventional injection pipeline (A4) in sequence through the first cylinder valve (1) and the first pressure reducing valve (2). The carbon dioxide cylinder (102) is connected to the conventional injection pipeline (A4) in sequence through the second cylinder valve (3) and the second pressure reducing valve (4). The nitrogen cylinder (103) is connected to the conventional injection pipeline (A4) in sequence through the third cylinder valve (5) and the third pressure reducing valve (6). The conventional injection pipeline (A4) is provided with a gas source main valve (7), a booster pump (8), a booster storage tank (9), a fourth pressure reducing valve (10), a two-position four-way valve (11), a switch needle valve (13), a four-way pipe joint (43), and an inlet pressure sensor (14) in sequence along the airflow direction. The third port of the two-position four-way valve (11) is connected to a waste vent valve (12). The fourth port of the two-position four-way valve (11) is connected to the third port of the four-way pipe connector (43) via a vacuum line (A3). The vacuum line (A3) is provided with a vacuum pump (38), a methane gas receiving valve (39), a reference tank (40) and a methane gas output valve (42) in sequence from the two-position four-way valve (11) to the four-way pipe connector (43). The reference tank (40) is provided with a reference tank pressure sensor (41).

3. The multifunctional coal sample testing device based on nuclear magnetic resonance according to claim 2, characterized in that: One end of the gas displacement pipeline (A2) is connected to the fourth interface of the four-way pipe fitting (43); the stable displacement pump (44) is connected to the displacement main pipeline (A7), the other end of the gas displacement pipeline (A2) is connected to the displacement main pipeline (A7), and a drain valve (31) is provided at the other end of the displacement main pipeline (A7). The gas displacement pipeline (A2) is provided with a power gas switch valve (30), a gas displacement storage tank (32), a first displacement gas switch valve (34), a three-way pipe joint (33), a gas heating container (35), and a displacement outlet valve (36) in sequence from the stable displacement pump (44) to the four-way pipe joint (43). The third port of the three-way pipe fitting (33) is connected between the pressurized storage tank (9) and the fourth pressure reducing valve (10) of the conventional injection line (A4) through the displacement gas line (A1). The displacement gas line (A1) is equipped with a second displacement gas switch valve (37).

4. The multifunctional coal sample testing device based on nuclear magnetic resonance according to claim 2, characterized in that: The coal sample holder (16) is equipped with a transparent rubber sleeve (46) for installing cylindrical coal samples. The center line of the transparent rubber sleeve (46) is set along the left and right direction. The transparent rubber sleeve (46) is equipped with an annular confining pressure cavity. The left and right sides of the coal sample holder (16) are respectively equipped with confining pressure liquid injection ports (47) that communicate with the annular confining pressure cavity. The left and right ends of the coal sample holder (16) are both sealed pipe joints (48). The sealed pipe joint (48) at the left end is connected to the conventional injection pipeline (A4), and the sealed pipe joint (48) at the right end is connected to the test pipeline (A5).

5. The multifunctional coal sample testing device based on nuclear magnetic resonance according to claim 4, characterized in that: The confining pressure control pipeline (A6) is provided with a left confining pressure loading joint (29), a preheater (21), a confining pressure controller (23) and a right confining pressure loading joint (19) from left to right. The left confining pressure loading joint (29) and the right confining pressure loading joint (19) are connected to the confining pressure liquid injection ports (47) on the left and right sides, respectively. The preheater (21) is provided with a heating temperature sensor (22), the confining pressure controller (23) is provided with a confining pressure sensor (24), the confining pressure controller (23) is connected to a confining pressure liquid storage tank (25), and the coal sample holder (16) is provided with a coal sample temperature sensor (15) for real-time monitoring of the internal temperature of the transparent rubber sleeve (46).

6. The multifunctional coal sample testing device based on nuclear magnetic resonance according to claim 4, characterized in that: The test pipeline (A5) is provided with an outlet pressure sensor (18), a back pressure valve (26), a gas measuring valve and a flow meter (28) from left to right. The back pressure valve (26) is connected to a manual pump (27) for adjusting the pressure of the back pressure valve.

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