A deep coal seam high pressure jet breaking physical fluidization mining simulation device and method

Abstract

The present application relates to a kind of deep coal seam high-pressure jet breaking physical fluidization mining simulation device and method.Deep coal seam high-pressure jet breaking physical fluidization mining simulation device and method, comprising: triaxial pressurization experimental device;Hydraulic slotting experimental device, connect with the triaxial pressurization experimental device;Gas pressurizing device, connect with the triaxial pressurization experimental device;Three-phase backflow liquid conveying device, connect with the triaxial pressurization experimental device.The present application also provides a kind of method for simulating deep coal seam high-pressure jet breaking physical fluidization coal and coalbed gas co-mining using the simulation device as described in the present application.The present application accurately realizes the simulation of high-pressure jet breaking process and coal and coalbed gas co-mining process of deep coal seam with depth of 1500-2500m, so as to accurately evaluate the pressure-relief permeability-improving effect of deep coal seam, improve the mining efficiency of coal seam and oil and gas resources, while reducing the loss of equipment.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of deep coal seam fluidization mining, in particular to a deep coal seam high-pressure jet breaking physical fluidization mining simulation device and method. BACKGROUND

[0002] Coalbed methane is an important part of China's unconventional natural gas resources. According to estimates, the total amount of coalbed methane resources in China at a depth of 2000 m is about 82 trillion cubic meters, of which the recoverable resource amount is 10 trillion cubic meters. With the increasing depletion of shallow resources in China's coal mines, the mining depth of underground mining is increasing at a rate of 8-12 m per year. According to incomplete statistics, the mining depth of more than 50 mines in China has exceeded 1000 m (some have been closed). Therefore, it is particularly necessary to study the mining method of deep coal seams at a depth of 1500-2000 m.

[0003] With the increase of mining depth, the risks and challenges faced by deep well mining are also increasing. The prominent coal and gas threat, soft rock support problem, small coal pillar ground pressure problem and ground temperature problem are becoming increasingly serious, and deep mining is facing huge safety and technical challenges. With the gradual increase of gas pressure and gas content in deep coal seams, the coal seam permeability gradually decreases, resulting in increased difficulty in coal seam gas extraction. Specifically, the pre-extraction concentration is low and the pre-extraction gas volume rapidly decays. As we all know, low permeability is the main factor affecting the effect of coal seam gas extraction and restricting the safety production of coal mines. Therefore, improving the permeability of coal seams is the key to solving the problem of gas control.

[0004] In recent years, with the continuous development of coal mine gas control technology, various gas permeability enhancement measures have been widely used in gas disaster control, mainly including hydraulic punching, hydraulic slotting, hydraulic fracturing, etc. Among them, the hydraulic slotting technology uses high-pressure jet water as a medium to cut the coal sample in the borehole, thereby forming new slots in the borehole to increase the permeability of the coal seam and reduce the stress of the original rock coal seam. However, the water pressure for hydraulic slotting is generally 30-60 MPa, which is suitable for medium-hard coal seams, and the depth of the slot is generally not more than 1 m. Therefore, when it is applied to deep coal seams with high ground stress and soft and broken coal seams, there are often frequent problems of drilling in the construction process, which seriously affects the construction efficiency. At the same time, for deep underground coal seam mining, since the hydraulic slotting technology is not suitable for soft and broken coal seams, and the slots produced by hydraulic slotting are also easy to close under high stress conditions, resulting in a significant reduction in coal seam and gas extraction rate.

[0005] Although the mechanism and method of seam fracturing in the prior art are studied, such as a water jet cutting device and a seam cutting method capable of realizing abrasive recycling and adjusting a cutting angle, which can effectively avoid water tail blockage caused by abrasive accumulation in the water tail, increase the utilization rate of abrasive, and cut wider and longer slots by precisely adjusting the cutting angle to take full advantage of the characteristics of ground stress to increase the pressure relief effect of the slots under the same working conditions. For example, a water jet cutting horizontal guide device based on a gravity guide mechanism and a method of use, which uses a hollow drill rod inserted into the seam and a guide and a cutting device installed at the front end of the drill rod, and is associated with a gravity guide ball to control the high-pressure water pipe, so as to ensure that the cutting direction of the water jet cutting device is in the horizontal direction, each borehole is subjected to water jet cutting in the horizontal direction, and finally a protective layer inside the seam is formed to efficiently relieve pressure and increase the permeability of the seam. However, the above methods have the following problems: 1) unable to simulate the triaxial ground stress state of deep coal and rock, and unable to accurately obtain the water jet cutting pressure relief effect of deep stratum coal and rock; 2) unable to simulate the coupling effect of temperature field and stress field of deep stratum coal and rock, and difficult to obtain accurate measurement results; 3) the seam pressure relief method and experimental equipment are not suitable for the soft and broken condition of deep stratum seam, and the cracks of conventional water jet cutting are easily closed under high ground stress, which leads to experimental failure, increases the loss of equipment, and reduces the mining efficiency of coal seam and oil and gas resources. SUMMARY

[0006] The purpose of the present application is to provide a deep seam high-pressure jet breaking physical fluidization mining simulation device and method, which can accurately simulate the high-pressure jet breaking process of deep seam with a depth of 1500-2500m and the coal and coal seam gas co-mining process, so as to accurately evaluate the pressure relief and permeability improvement effect of deep seam, improve the mining efficiency of coal seam and oil and gas resources, and reduce the loss of equipment.

[0007] In order to achieve the above purpose, the technical scheme adopted by the present application is as follows:

[0008] A deep seam high-pressure jet breaking physical fluidization mining simulation device, comprising:

[0009] A triaxial pressure experiment device for simulating the pressure environment of deep underground coal and rock;

[0010] A water jet cutting experiment device connected with the triaxial pressure experiment device for simulating water jet cutting;

[0011] A gas pressurizing device connected with the triaxial pressure experiment device for simulating the pore pressure provided by the gas in the deep underground coal and rock stratum;

[0012] A three-phase backflow liquid conveying device is connected with the triaxial compression experimental device and is used for simulating separation of solid-liquid-gas three-phase mixed backflow liquid.

[0013] According to the technical means, the triaxial compression experimental device is arranged, so that a complex pressure environment of deep underground coal rock is accurately simulated, and a real and reliable background condition is provided for the experiment. By introducing the hydraulic slotting experimental device, the gas pressurizing device and the three-phase backflow liquid conveying device, the device can simulate multiple processes such as hydraulic slotting, gas pore pressure and separation of solid-liquid-gas three-phase mixed backflow liquid, and meet the all-around research demand of deep coal seam co-mining. The device integrates multiple experimental functions, can simultaneously perform multiple experiments, and greatly improves the experimental efficiency. Meanwhile, the ingenious connection design between the devices facilitates experimental operation and maintenance. The device can be used not only for research of deep coal seam co-mining, but also can be applied to other related fields such as underground resource development and geological disaster prediction, and has a wide application prospect.

[0014] Preferably, the triaxial compression experimental device comprises:

[0015] An experimental box body is used for accommodating a coal rock test piece.

[0016] A jacking hydraulic cylinder is arranged at the bottom of the experimental box body and is used for providing axial pressure.

[0017] A door-shaped counterforce frame is arranged at the top of the experimental box body and is used for providing axial counterforce.

[0018] A confining pressure pump is connected with the experimental box body and is used for providing confining pressure.

[0019] The experimental box is provided for accommodating the coal rock sample, ensuring the closedness and safety of the experimental environment, so that the simulation device can simulate the real environment of the deep underground coal rock, and avoid the problem of errors in the simulation results caused by external environmental interference. The jacking hydraulic cylinder is arranged at the bottom of the experimental box, which can stably provide axial pressure to simulate the vertical pressure of the coal rock underground. The door-shaped counterforce frame is arranged at the top of the experimental box, which effectively provides axial counterforce, cooperates with the jacking hydraulic cylinder, and realizes the pressure loading of the coal rock sample in the axial direction. The confining pressure pump is connected with the experimental box to provide confining pressure for the coal rock sample, simulating the lateral pressure of the coal rock underground. By adjusting the output pressure of the jacking hydraulic cylinder and the confining pressure pump, the axial pressure and confining pressure in the experimental process can be accurately controlled, so as to simulate the stress state of the coal rock under different depths and geological conditions. This controllability makes the experimental results more accurate and reliable, which helps researchers to deeply understand the mechanical properties and deformation and failure mechanism of the deep underground coal rock. Through reasonable design of the simulation device, the connection between the components is tight and reliable, which ensures the safety and stability during the experiment. At the same time, the experimental device is easy to operate and easy to use, which reduces the operation difficulty and labor intensity of the experimental personnel. In addition, the experimental device also has good maintainability and expandability, which is convenient for subsequent upgrading and improvement.

[0020] Preferably, the experimental box is provided with:

[0021] The mounting hole is used for mounting the hydraulic slotting experiment device.

[0022] The oil inlet is connected with the confining pressure pump through a high-pressure oil pipe.

[0023] The wire inlet is connected with the heating device through a wire for simulating the high temperature state of the deep underground coal rock.

[0024] The gas inlet is used for mounting the gas pressurizing device.

[0025] Preferably, the experimental box and the jacking hydraulic cylinder are further provided with a mounting seat.

[0026] Preferably, the jacking hydraulic cylinder is connected with a hydraulic servo controller.

[0027] Preferably, the hydraulic slotting experiment device comprises:

[0028] The sleeve pipe is arranged in the mounting hole of the experimental box and extends into the wellhead of the coal rock sample.

[0029] The oil pipe is arranged in the sleeve pipe.

[0030] Preferably, one end of the oil pipe is connected with a rotary joint, a valve, a booster pump and a water tank in sequence.

[0031] Preferably, a tubing centralizer and a nozzle are mounted on the oil pipe, and the nozzle is located below the tubing centralizer.

[0032] The inner wall of the sleeve is provided with a sliding rail, and the nozzle is in sliding fit with the sliding rail.

[0033] By setting a rotary joint on the oil pipe, the oil pipe can rotate radially, and by setting a sliding rail in sliding fit with the nozzle, the oil pipe can move axially, realizing the co-mining of coal and coalbed methane in the vertical direction of deep underground coal rock, and realizing the omnidirectional flexible adjustment of the oil pipe in the coal rock test piece, thereby ensuring that the high-pressure water jet can accurately act on the target area according to the simulation requirements, improving the accuracy and efficiency of the simulation of hydraulic slotting. This design not only enhances the adaptability and flexibility of the device, but also provides more accurate and reliable experimental conditions for the simulation of deep coal seam high-pressure jet crushing physical fluidization mining.

[0034] Preferably, the three-phase backflow liquid conveying device comprises:

[0035] A backflow liquid pipeline, one end of the backflow liquid pipeline being connected to the sleeve;

[0036] A three-phase solid-liquid-gas separation device, the other end of the backflow liquid pipeline being connected to the three-phase solid-liquid-gas separation device.

[0037] Preferably, the three-phase solid-liquid-gas separation device comprises: a fairing, an exhaust pipe arranged in the fairing, and a reflecting disc arranged on the exhaust pipe and located in the fairing; the fairing is provided with a liquid discharge port and a solid discharge port, and a screen is mounted at the liquid discharge port.

[0038] Preferably, the gas pressurizing device comprises:

[0039] An upper pressure head, the upper pressure head being arranged at a gas inlet at the top of the experimental box;

[0040] A lower pressure head, the lower pressure head being arranged at a gas inlet at the bottom of the experimental box;

[0041] A flow guide pipe, one end of the flow guide pipe being connected to a high-pressure gas cylinder, and the other end of the flow guide pipe being connected to the upper pressure head and / or the lower pressure head.

[0042] Through the arrangement of the upper pressing head and the lower pressing head, the gas pressurization can be carried out at the top and the bottom of the experimental box simultaneously, and the efficiency and uniformity of the gas pressurization are improved. At the same time, the connection design of the flow guide pipe enables the gas in the high-pressure gas cylinder to flow smoothly into the upper pressing head and / or the lower pressing head, further improving the pressurization effect. Due to the joint action of the upper pressing head and the lower pressing head, and the precise guidance of the flow guide pipe, the device can realize rapid and efficient pressurization of the gas in the coal rock sample in the experimental box, thereby accurately simulating the pore pressure of the deep underground coal rock. The structural design of the device is simple and clear, and the operation process is simple and easy to understand. The experimental personnel only need to connect the high-pressure gas cylinder to the upper pressing head and / or the lower pressing head through the flow guide pipe, and the gas pressurization operation can be realized, which greatly reduces the operation difficulty and complexity. The gas pressurization device is suitable for various experimental scenes and experimental requirements, and can meet the requirements of different experiments for gas pressure. At the same time, the structural design is flexible and variable, and can be adaptively adjusted according to the specific experimental requirements. The operation process of the device is simple and safe, and can effectively avoid safety hazards in the experimental process.

[0043] Preferably, the depth of the deep underground coal rock is 1500-2500 meters.

[0044] Preferably, the simulation device can provide a confining pressure of 60 MPa, a temperature of 120 DEG C, and a pore pressure of 30 MPa.

[0045] Preferably, the wellbore of the simulation device can withstand a pressure of 80 MPa, and the wellhead can withstand a pressure of 100 MPa.

[0046] The application also provides a method for simulating deep coal seam high-pressure jet breaking physical fluidization coal and coalbed gas co-mining by using the simulation device as described in the application, comprising the following steps:

[0047] The coal rock sample is placed in the experimental box of the triaxial pressurization experimental device, and the triaxial pressurization experimental device is used to apply axial pressure, axial counterforce and confining pressure to the coal rock sample to simulate the triaxial pressure of the deep underground coal rock. The gas pressurization device is used to apply pore pressure to the coal rock sample to simulate the pore pressure of the deep underground coal rock. The hydraulic slotting experimental device is used to cut the coal rock sample to simulate hydraulic slotting. The fluidized liquid mixture obtained by cutting flows into the three-phase backflow liquid conveying device through the casing of the triaxial pressurization experimental device. The three-phase backflow liquid conveying device is used to separate the fluidized liquid mixture to simulate the separation of the solid-liquid-gas three-phase mixed backflow liquid.

[0048] The present application can accurately simulate the complex pressure environment of deep underground coal rock by ingeniously designing a triaxial compression experimental device to apply axial pressure, axial reaction force and confining pressure to the coal rock sample, and by applying pore pressure through a gas pressurizing device, thereby improving the accuracy and reliability of the simulation experiment. By setting a hydraulic slotting experimental device to cut the coal rock sample, the hydraulic slotting process during actual mining can be simulated, which helps to study the influence of hydraulic slotting on coal rock crushing and coalbed methane release. By setting a three-phase mixed reflux liquid separation device, the flow state liquid mixture obtained by cutting flows into the three-phase reflux liquid conveying device through the sleeve of the triaxial compression experimental device, and is separated through the device, which can simulate the treatment process of the solid-liquid-gas three-phase mixed reflux liquid during actual mining, and helps to study the composition and properties of the reflux liquid, providing an important basis for the co-mining of coalbed methane and coal. The present application combines the simulation device with the method of deep coal seam high-pressure jet breaking physical fluidization of coal and coalbed methane co-mining, proposes a new experimental method, provides a new idea and technical means for related field research, can be widely applied to the co-mining of coalbed methane and coal, and related fields of geology, mining, energy, etc., and has important practical value and application prospect.

[0049] The beneficial effects of the present application are:

[0050] The deep coal seam high-pressure jet breaking physical fluidization mining simulation device of the present application accurately simulates the complex pressure environment of deep underground coal rock by setting a triaxial compression experimental device, thereby providing a real and reliable background condition for the simulation experiment. By introducing the hydraulic slotting experimental device, the gas pressurizing device and the three-phase reflux liquid conveying device, the device can simulate multiple processes such as hydraulic slotting, gas pore pressure and separation of solid-liquid-gas three-phase mixed reflux liquid, thereby meeting the all-round research needs of deep coal seam co-mining. The device integrates multiple experimental functions in one, can perform multiple simulation experiments at the same time, greatly improves the authenticity and comprehensiveness of the simulation of actual coal and coalbed methane co-mining, and improves the simulation experiment efficiency. At the same time, the ingenious connection design between the devices facilitates experimental operation and maintenance. The device can not only be used for the research of deep coal seam co-mining, but also can be applied to other related fields such as underground resource development, geological disaster prediction, etc., and has a wide application prospect.

[0051] The deep coal seam high-pressure jet breaking physical fluidization mining simulation device of the application can be used for simulating 1500-2500m deep coal and coal seam gas storage environment and carrying out high-pressure water jet cutting and cavity forming physical fluidization mining simulation experiment. The triaxial pressure experiment device is ingeniously set to apply axial and radial pressure, and the radial confining pressure can be provided by a confining pump to 60Mpa. A gas pressurizing device is designed to apply gas hole pressure to the coal rock, and the highest can reach 30MPa. The temperature heating device heats the oil around the coal rock sample to continuously increase the temperature, simulating the actual deep high-temperature environment in the well. At the same time, in order to enhance the effect of hydraulic cutting and pressure relief of deep underground coal rock, the oil pipe is designed to be axially movable and radially rotatable, to drive the nozzle to move, so as to achieve better cutting and pressure relief effect, and a cavity can be formed on the coal seam, so that the hydraulic jet breaking coal and coal seam gas flow out of the wellbore with the fluid, effectively realizing the simulation of deep coal resource fluidization mining, and directly designing a three-phase solid-liquid separator at the wellhead to separate different mineral resources, greatly improving the mining efficiency, and having popularization and application value in the field of deep coal seam fluidization mining technology. BRIEF DESCRIPTION OF DRAWINGS

[0052] Figure 1 It is a structural schematic diagram of the deep coal seam high-pressure jet breaking physical fluidization mining simulation device and method.

[0053] Figure 2 It is a partial view of the experimental box and the coal rock sample assembly.

[0054] Figure 3 It is a partial view of the casing, oil pipe, nozzle, slide rail and pressure strain gauge assembly.

[0055] Figure 4 It is a partial view of the wellhead structure.

[0056] Figure 5 It is a partial view of the simulated oil pipe string structure.

[0057] Wherein, 1-coal rock sample, 101-hollow cavity; 2-experimental box, 201-mounting hole, 202-oil inlet, 203-wire inlet, 204-gas inlet, 205-lower box, 206-cover plate; 3-hydraulic cylinder; 4-gate-shaped counterforce frame; 5-confining pressure pump; 6-high-pressure oil pipe; 7-heating device; 8-mounting seat; 9-hydraulic servo controller; 10-casing; 11-oil pipe; 12-rotary joint; 13-valve; 14-boosting pump; 15-water tank; 16-oil pipe centralizer; 17-nozzle; 18-rail; 19-backflow liquid pipeline; 20-upper pressure head; 21-lower pressure head; 22-flow guide pipe; 23-high-pressure gas cylinder; 24-pressure test valve; 25-pressure gauge; 26-pressure strain gauge; 27-flow monitoring meter; 28-damper, 281-liquid discharge port, 282-solid discharge port; 29-exhaust pipe; 30-reflective disc; 31-sieve; 32-pressure reducing valve; 33-pad. DETAILED DESCRIPTION

[0058] The advantages and effects of the present application will be apparent to those skilled in the art from the description set forth herein. The present application can be implemented or applied in other different specific embodiments, and the details in the description can be modified or changed based on different views and applications without departing from the spirit of the present application. It should be understood that the preferred embodiments are only for illustrating the present application, but not for limiting the protection scope of the present application. EMBODIMENT

[0059] As Figures 1 to 5 shown, a deep coal seam high-pressure jet breaking physical fluidization mining simulation device and method, comprising:

[0060] Triaxial pressure experiment device, for simulating the pressure environment of deep underground coal rock;

[0061] Hydraulic slotting experiment device, connected with the triaxial pressure experiment device, for simulating hydraulic slotting;

[0062] Gas pressurizing device, connected with the triaxial pressure experiment device, for simulating the pore pressure provided by the gas in the deep underground coal rock stratum;

[0063] Three-phase backflow liquid conveying device, connected with the triaxial pressure experiment device, for simulating the separation of solid-liquid-gas three-phase mixed backflow liquid.

[0064] In some embodiments, the triaxial pressure experiment device comprises:

[0065] Experimental box 2 for containing coal rock sample 1;

[0066] The lifting hydraulic cylinder 3 is arranged at the bottom of the experimental box 2 and is used to provide axial pressure.

[0067] The door-shaped counterforce frame 4 is arranged at the top of the experimental box 2 and is used to provide axial counterforce. The crossbeam of the door-shaped counterforce frame 4 is in contact with the experimental box 2 through the cushion block 33.

[0068] The confining pressure pump 5 is connected with the experimental box 2 and is used to provide confining pressure.

[0069] During the simulation experiment, the lifting hydraulic cylinder 3 provides power, the two cushion blocks 33 with a height of 10 mm and the door-shaped counterforce frame 4 provide axial counterforce, the cushion block 33 can provide supporting counterforce to prevent damage of the coal rock sample 1 or the device due to excessive axial pressure, and the pressure size is controlled by the hydraulic servo controller 9 to ensure that the lifting rate of the lifting hydraulic cylinder 3 remains constant.

[0070] For example, the installation box 2 includes a lower box 205 and a cover plate 206 mounted on the lower box 205. The lower box 205 and the cover plate 206 are fixed together by bolt assembly.

[0071] In some embodiments, the experimental box 2 is provided with:

[0072] The mounting hole 201 is used to mount the hydraulic slotting experiment device.

[0073] The oil inlet 202 is connected with the confining pressure pump 5 through the high-pressure oil pipe 6, and the confining pressure pump 5 is used to inject oil into the inside of the lower box 205 to provide oil pressure. The pressure size and the pressurizing rate are controlled by the servo controller, and the maximum confining pressure that can be provided is 60 MPa.

[0074] The wire inlet 203 is connected with the heating device 7 through the wire and is used to simulate the high-temperature state of deep underground coal rock.

[0075] The gas inlet 204 is used to mount a gas pressurizing device.

[0076] The experimental box 2 is further provided with the mounting seat 8 between the experimental box 2 and the lifting hydraulic cylinder 3, and the mounting seat 8 is provided with vertical movement power by the lifting hydraulic cylinder 3.

[0077] The lifting hydraulic cylinder 3 is connected with the hydraulic servo controller 9.

[0078] The confining pressure pump 5 is used to inject oil into the inside of the experimental box 2 to provide oil pressure. The pressure size and the pressurizing rate are controlled by the servo controller, and the maximum confining pressure that can be provided is 60 MPa. The mounting seat 8 is provided with vertical movement power by the lifting hydraulic cylinder 3, the door-shaped counterforce frame 7 provides axial counterforce, and thus the triaxial stress state of deep underground coal rock is simulated.

[0079] In some embodiments, the hydraulic slotting experimental device comprises:

[0080] The sleeve 10 is arranged through the mounting hole 201 of the experimental box 2 and extends into the wellhead of the coal rock sample 1.

[0081] The oil pipe 11 is arranged in the sleeve 10.

[0082] For example, the mounting hole 201 is arranged on the cover plate 206, the oil pipe 11 is sleeved in the sleeve 10, and then they are arranged through the mounting hole 201 together. The sleeve 10 is fixed at the mounting hole 201 by bolts, and the pressure test valve 24 is arranged on the oil pipe 11 near the mounting hole 201.

[0083] The oil inlet 202 is arranged on the side wall of the lower box 205, one end of the high-pressure oil pipe 6 is arranged in the oil inlet 202, and the other end is connected to the confining pressure pump 5. After the connection is completed, the hole is sealed with strong glue to ensure that the internal environment of the experimental box 2 is sealed.

[0084] The wire inlet 203 is arranged on the side wall of the lower box 205, the wire inlet 203 is connected to the heating device 7 through the wire, the heating device 7 is used to heat the oil, the temperature can reach 120℃, to simulate the high temperature state of deep underground coal rock, and after the connection is completed, the hole is sealed with strong glue to ensure that the internal environment of the experimental box 2 is sealed.

[0085] In the actual simulation experiment process, a hole is drilled on the top of the coal rock sample 1 to simulate the wellhead, the inner diameter of the wellhead is designed to be 30-50 mm, the casing 10 extends into the wellhead, and the casing 10 is stabilized by pouring concrete to cement the well. The oil pipe 11 is inserted into the middle of the casing 10, and the oil pipe 11 is connected to the wellhead ground device, which specifically includes: sequentially connected rotary joint 12, valve 13, pressure gauge 25, booster pump 14 and water tank 15. Among them, the oil pipe 11 can transport high-pressure water, the water in the water tank 15 provides pressure through the booster pump 14, has the effect of high-pressure jet, is transported through the oil pipe 11 and is ejected by the nozzle 17, the pressure of the booster pump 14 can be adjusted, and the value is displayed on the pressure gauge 25, the valve 13 can adjust the flow of high-pressure water, so as to achieve the appropriate jet flow. The space in which the casing 10 extends into the experimental box 2 is controlled by a valve to ensure that the space in the experimental box 2 is airtight, and a pressure test valve 24 is also used to control the middle of the oil pipe 11 to adjust the amount of high-pressure water in the oil pipe 11, while ensuring that there is no air leakage in the connected space. An oil pipe centralizer 16 is installed on the upper part of the nozzle 17, which can fix the oil pipe 11 in the middle of the casing 10 and prevent it from deviating due to the back pressure after the high-pressure water is ejected from the nozzle 17, so that the nozzle 17 is aligned with the cutting slot of the cavity, and a good cutting slot effect is obtained. The high-pressure water transported by the oil pipe 11 is ejected from the nozzle 17 and performs cutting and pressure relief on the coal rock sample 1 to form a hollow cavity 101. In order to improve the cutting effect in the deep formation environment, a slide rail 18 is designed on the edge of the casing 10 wall, the nozzle 17 moves up and down by controlling the movement of the oil pipe 11, the size of the nozzle 17 is consistent with that of the slide rail 18, and the nozzle 17 can be clamped on the slide rail 18 to move back and forth to cut, and the cutting effect is shown in Figure 3 . In order to match the movement of the nozzle 17, a series of axial slots are reserved on the wall of the casing 10, and the high-pressure water can cut and relieve pressure along the slots. After cutting and pressure relief by high-pressure water, a hollow cavity 101 is formed in the coal rock sample 1, and the internal coal seam and coal bed methane are continuously jetted and dispersed. Due to the water pressure, the pressure in the oil pipe 11 is greater than that in the casing 10 and the hollow cavity 101, and the gas-liquid-solid mixture formed after hydraulic jetting will return to the annular section of the casing 10 and flow to the wellhead part under the action of pressure difference.

[0086] In some embodiments, one end of the oil pipe 11 is sequentially connected with the rotary joint 12, the valve 13, the booster pump 14 and the water tank 15, and a pressure gauge 25 is installed on the pipeline between the valve 13 and the booster pump 14;

[0087] An oil pipe centralizer 16 is installed on the oil pipe 11, the oil pipe 11 is provided with a nozzle 17, the nozzle 17 is located below the oil pipe centralizer 16, and a pressure strain meter 26 is arranged at the nozzle 17;

[0088] A slide rail 18 is installed on the inner wall of the casing 10, and the nozzle 17 and the slide rail 18 are in sliding fit.

[0089] A rotating joint 12 is arranged on the oil pipe 11, so that the oil pipe 11 can rotate radially. A sliding rail in sliding fit with the nozzle 17 is arranged, so that the oil pipe 11 can move axially. Therefore, the hydraulic slitting can be realized by the mechanical external force, the axial movement and radial rotation of the oil pipe 11 through the sliding rail 18 and the rotating joint 12, the movement or sliding of the nozzle 17, the full slitting and pressure relief of the coal rock sample 1, and the full extraction and flow state integration of the coal and coal bed gas along the annulus of the casing 10.

[0090] The design of the rotating joint 12 enables the oil pipe 11 to rotate radially, and the direction and position of the oil pipe 11 can be flexibly adjusted. In actual coal seam mining, the geological conditions of the coal seam are complex and changeable. Therefore, in the simulation test, the rotating joint 12 is designed to adjust the oil pipe 11 according to the trend and form of the coal seam, better simulate the actual situation of the coal seam, improve the accuracy of the simulation, and provide more favorable technical support for actual coal seam mining. The reasonable design and use of the rotating joint 12 can reduce the wear of the oil pipe 11 during rotation and prolong the service life of the simulation device.

[0091] The sliding fit design of the sliding rail 18 and the nozzle 17 enables the oil pipe 11 to move axially to accurately control the axial position of the oil pipe as needed during coal seam mining, thereby realizing precise positioning and control of the mining area. At the same time, the use of the sliding rail 18 can reduce the friction of the oil pipe 11 during axial movement. In addition, the axial movement function of the sliding rail 18 can be combined with an automatic control system to realize automatic control and adjustment of the position of the oil pipe 11.

[0092] In actual simulation experiments, a hole is drilled on the top of the coal rock sample 1 to simulate the wellhead, the casing 10 is inserted from the wellhead, the oil pipe 11 is inserted into the middle of the casing 10 after cementing, and the oil pipe 11 is connected to the wellhead ground device, which includes the rotating joint 12, the valve 13, the pressure gauge 25, the booster pump 14 and the water tank 15 in sequence. At the same time, the oil pipe centralizer 16 is installed on the oil pipe 11 above the nozzle 17, so that the oil pipe 11 is fixed in the middle of the casing 10, ensuring the subsequent hydraulic slitting effect.

[0093] The axial movement of the oil pipe 11 drives the nozzle 17 to move in the sliding rail 18, an axial slot perpendicular to the cross section of the casing 10 is reserved on the casing 10, and the high-pressure water flow emitted by the nozzle 17 cuts the coal rock sample 1 through the reserved slot on the casing 10 to release pressure and form a hollow cavity 101. The radial rotation of the oil pipe 11 is realized through the rotating joint 12 to rotate by a certain angle, an axial slot parallel to the cross section of the casing 10 is reserved on the casing 10, and the high-pressure water flow emitted by the nozzle 17 cuts the coal rock through the reserved slot on the casing 10 to release pressure.

[0094] In some embodiments, the three-phase backflow liquid conveying device comprises:

[0095] The return liquid pipeline 19 is connected to the sleeve 10 at one end, and a flow monitoring meter 27 is installed on the return liquid pipeline 19, so that the solid-liquid-gas three-phase mixed return liquid in the return liquid pipeline 19 is monitored in real time through the flow monitoring meter 27, and the real-time flow of the liquid phase and the gas phase in the return liquid is obtained, so as to facilitate subsequent separation work.

[0096] The three-phase solid-liquid-gas separation device is connected to the other end of the return liquid pipeline 19.

[0097] For example, the three-phase solid-liquid-gas separation device includes a fairing 28, an exhaust pipe 29 arranged in the fairing 28, and a reflecting disc 30 arranged on the exhaust pipe 29 and located in the fairing 28; the fairing 28 is provided with a liquid outlet 281 and a solid outlet 282, and a screen 31 is arranged at the liquid outlet 281.

[0098] In actual simulation experiments, the solid-liquid-gas three-phase mixed return liquid flows along the annular space of the sleeve 10 under the action of pressure difference, flows through the return liquid pipeline 19 after the valve, enters the three-phase solid-liquid-gas separation device, and then is separated into mineral resources through the three-phase solid-liquid-gas separation device. Specifically, the fairing 28 in the three-phase solid-liquid-gas separation device flows the gas-liquid-solid mixture entering the three-phase solid-liquid-gas separation device, the fairing 28 rotates and performs centrifugal motion, and generates a large centrifugal force to separate the liquid and solid mixture from the gas. The centrifugal forces of the liquid and solid mixture and the gas are different, the gas rotates at the top of the separator, and then enters the exhaust pipe 29 in the center of the fairing 28 due to the pressure difference caused by accumulation and is discharged through the exhaust pipe 29; the liquid and solid mixture has a larger centrifugal force, is adsorbed on the wall of the separator, and then flows to the liquid outlet 271. The liquid contains solid coal residue mixture, and the liquid is separated through the filtering action of the screen 31, and the solid is accumulated at the solid outlet 272. The reflecting disc 30 is arranged in the middle of the exhaust pipe 29, so that the volume of the gas is accumulated and expanded upward, thereby preventing the gas from diffusing and overflowing from the liquid outlet. The flow monitoring meter 27 can realize real-time monitoring of the proportion and corresponding flow of the gas phase and the solid phase in the solid-liquid-gas three-phase mixed return liquid, and the separation of resources can be realized through the solid-liquid separator, which is beneficial to purification and extraction.

[0099] In some embodiments, the gas pressurizing device includes:

[0100] The upper pressure head 20 is arranged at the gas inlet 204 at the top of the experimental box 2.

[0101] The lower pressure head 21 is arranged at the gas inlet 204 at the bottom of the experimental box 2.

[0102] The flow guide pipe 22 is connected to the high-pressure gas cylinder 23 at one end and connected to the upper pressure head 20 and / or the lower pressure head 21 at the other end, and a pressure reducing valve 32 is further arranged on the flow guide pipe 22.

[0103] The gas pressurizing device provides the coal rock sample 1 with a pore pressure of up to 30 MPa, and ensures that the pressure is increased synchronously with the oil pressure when the gas is injected, thereby simulating the complex stress conditions of the underground rock stratum and ensuring the authenticity of the simulation process. The pressure is controlled by the pressure reducing valve 32 and the real-time data is displayed on the pressure gauge. After the experiment is completed, the gas is discharged from the lower pressure head 21 due to the pressure difference, and the exhaust gas is stored in the high-pressure gas cylinder 23 connected to the lower pressure head 21.

[0104] For example, the gas inlet 204 at the top of the experimental box 2 is provided on the cover plate 206, and the upper pressure head 20 is provided in the gas inlet 204 on the cover plate 206. The gas inlet 204 at the bottom of the experimental box 2 is provided at the bottom of the lower box 205, and the lower pressure head 21 is provided in the gas inlet 204 at the bottom of the lower box 205. After the upper pressure head 20 and the lower pressure head 21 are installed, strong glue is used for sealing to ensure a high-pressure sealed environment inside the experimental box.

[0105] In some embodiments, the depth of the deep underground coal rock is 1500-2500 meters.

[0106] In some embodiments, the experimental device can provide a confining pressure of 60 MPa, a temperature of 120°C, and a pore pressure of 30 MPa.

[0107] In some embodiments, the wellbore of the experimental device can withstand a pressure of 80 MPa, and the wellhead can withstand a pressure of 100 MPa.

[0108] In some embodiments, a method for simulating the co-extraction of physically fluidized coal and coalbed methane by high-pressure jet crushing in deep coal seams using the simulation experimental device of any of the above embodiments is also provided, comprising the following steps:

[0109] The coal rock sample is placed in the experimental box of the triaxial pressurizing experimental device. The triaxial pressurizing experimental device applies axial pressure, axial counterforce, and confining pressure to the coal rock sample. The gas pressurizing device applies pore pressure to the coal rock sample to simulate the pressure environment of the deep underground coal rock. The hydraulic slotting experimental device cuts the coal rock sample to simulate hydraulic slotting. The fluidized liquid mixture obtained by cutting is flowed into the three-phase backflow liquid conveying device through the casing of the triaxial pressurizing experimental device. The three-phase backflow liquid conveying device separates the fluidized liquid mixture to simulate the separation of the solid-liquid-gas three-phase mixed backflow liquid.

[0110] For example, the method for simulating the co-extraction of physically fluidized coal and coalbed methane by high-pressure jet crushing in deep coal seams using the simulation experimental device of any of the above embodiments comprises the following steps:

[0111] S1, prepare coal rock sample 1, and drill a hole on the top of coal rock sample 1 to simulate the wellhead, the hole diameter is about 50mm, and uniformly coat a layer of polyurethane sealant about 1mm on the outer surface of coal sample 1; the size of coal rock sample 1 used in this experiment is length direction (i.e. X axis direction) 300.00mm, width direction (i.e. Y axis direction) 300.00mm, height direction (i.e. Z axis direction) 300.00mm.

[0112] S2, place the coal rock sample 1 treated in S1 and the oil for heating in the lower box 205 of the triaxial compression testing device, and fix the lower box 205 to the mounting seat 8; fix the mounting seat 8 to the jacking hydraulic cylinder 3, and connect the jacking hydraulic cylinder 3 to the hydraulic servo controller 9 to control the pressure of the jacking hydraulic cylinder 3 through the hydraulic servo controller 9; install the high-pressure oil pipe 6 at the oil inlet 202, and connect the high-pressure oil pipe 6 to the confining pressure pump 5, the diameter of the oil inlet 202 is about 2cm; insert the wire at the wire inlet 203, and connect the wire to the heating device 7 to heat the oil to simulate the high temperature state of deep underground coal rock, and seal the hole with strong glue after connection to ensure the internal environment of the experimental box 2 is airtight. Among them, the lower box 205 is made of 25mm thick steel plate, which can withstand 60MPa confining pressure, 30MPa pore pressure, simulate wellbore diameter of 30-50mm, and withstand 80MPa pressure; simulate wellhead (double): withstand 100MPa pressure.

[0113] S3, install the slide rail 18 and the pressure strain meter 26 on the inner wall surface of the casing 10 of the hydraulic slotting experiment device in advance, and inject concrete into the casing 10 to simulate wellbore cementing measures, then pass the casing through the installation hole 201 of the cover plate 206 and consolidate it in the middle of the coal rock sample 1 wellhead; preinstall multiple nozzles 17 and oil pipe centralizers 16 on the oil pipe 11 with a diameter of about 20mm, and the oil pipe centralizers 16 are located above the nozzles 17, then insert the oil pipe 11 into the middle of the casing 10 and consolidate it, the oil pipe centralizer 16 can keep the oil pipe 11 in the middle of the casing 10 and will not deviate due to the backwash force of high pressure water.

[0114] S4, extend the casing 10 annulus part at the wellhead to connect the high-pressure pipe as the backflow pipe 19, install the flow monitoring meter 27 on the backflow pipe 19, and connect the other end of the backflow pipe 19 to the three-phase solid-liquid-gas separation device; set the upper pressure head 20 of the gas pressurizing device in the gas inlet 204 on the cover plate 206, and set the lower pressure head 21 in the gas inlet 204 at the bottom of the lower box 205; connect the upper pressure head 20 and the lower pressure head 21 with one end of the flow guide pipe 22, respectively, and connect the other end of the flow guide pipe 22 to the high-pressure gas cylinder 23, while setting the pressure gauge and the pressure reducing valve 32 on the flow guide pipe 22, and sealing with strong glue after installation to ensure the high-pressure closed environment inside the experimental box. After the experiment, the waste gas flows through the flow guide pipe 22 to the high-pressure gas cylinder 23 connected with the lower pressure head 21 due to the pressure difference.

[0115] S5, connect the rotary joint 12, the valve 13, the pressure gauge 25, the booster pump 14 and the water tank 15 in sequence at the end of the oil pipe 11 located at the wellhead. The high-pressure water for hydraulic slotting is provided by the booster pump 14. Install the pressure test valve 24 on the oil pipe 11 to control the flow in the oil pipe 11. After the external connection is completed, cover the cover plate 206 on the top of the lower box 205 and check the air tightness. The cover plate 206 and the lower box 205 are fixed by bolts to ensure that all valves are in a closed state, and the air tightness of each interface is checked to ensure no water leakage and no oil leakage.

[0116] S6, fix two pads 33 on the cover plate 206, then install the door-shaped counterforce frame 4 on the pads 33, and set the support bracket of the door-shaped counterforce frame 4 on the ground to support the entire device; connect the data acquisition unit to the components for collecting temperature and pressure, then connect the wiring of the control unit and the data acquisition unit, and check whether the data acquisition unit is running normally and use the vacuum pump to perform vacuum treatment on each pipeline in the experimental device.

[0117] S7, set the loading pressure and loading rate of the experimental device through the computer and the hydraulic servo controller 9, set the pressure to the specified value through the confining pressure pump 5, open the gas pressurizing device, set the specified gas pressure through the pressure reducing valve 32 to simulate the pore pressure, open the heating device 7 to heat the oil around the coal rock sample 1 to the preset temperature, apply the axial pressure, confining pressure and pore pressure at the same time, and control the specific pressure by operating the computer and the confining pressure pump, and finally stabilize at the set value.

[0118] S8, open the valve 13, through the action of booster pump 14, water in the water tank 15 is pressurized into high pressure water, the pressure is adjusted by the pressure gauge 25 on the oil pipe 11; adjust to the appropriate pressure size and open the pressure test valve 33, water flow into the coal rock test piece 1, cut the coal rock test piece 1 from the nozzle 17. By mechanical external force drag oil pipe 11, make the nozzle 17 on the oil pipe 11 move back and forth in the groove of slide rail 18, cut the coal rock test piece 1 from the reserved slot of casing 10; water jet continues to cut, a hollow cavity 101 is formed in the coal rock test piece 1, the coal and coal bed gas in it form a liquid mixture under the action of jet, the jet process records the pressure near the wellbore through the pressure strain gauge 26.

[0119] S9, high pressure water flows in the hollow cavity 101 of the coal rock test piece 1 and the oil pipe 11, the pressure is greater than the annulus of the casing 10, so that the flow state mixture in the hollow cavity 101 is flowed to the casing 10 and flows to the wellhead direction due to the pressure difference; open the valve, make the flow state mixture flow through the backflow liquid pipe 19, real-time detect the flow of gas-liquid phase in the flow state mixture through the flow monitoring meter 27, then flow to the three-phase solid-liquid-gas separation device; the three-phase solid-liquid-gas separation device continues to operate, the flow state mixture enters and performs centrifugal motion, the gas and liquid can be separated due to the different centrifugal force of different phases, finally the coal particle solid and fluid are filtered through the screen 31, to achieve the purpose of diversion.

[0120] S10, when the value of pressure strain gauge 26 changes is no longer obvious, it indicates that the hydraulic slotting of the hollow cavity 101 is completed, the equipment can be unloaded for the next experiment, the nozzles can be installed on the left and right sides of a coal rock test piece 1 for jet, the oil pipe 11 is radially rotated and axially moved to achieve better hydraulic slotting effect, and the coal resources and underground resources are used to the greatest extent. After the experiment, the corresponding oil pipe and casing are cleaned, the data is recorded, the cavity effect of coal rock hydraulic slotting is recorded by taking pictures, and the coal bed gas and coal resources collected are collected.

[0121] In summary, the deep coal seam high pressure jet breaking physical fluidization mining simulation device of the present application, by setting up a triaxial compression testing device, accurately simulates the complex pressure environment of deep underground coal and rock, provides real and reliable background conditions for simulation experiments; through the introduction of the water jet cutting experiment device, the gas pressurizing device and the three-phase backflow liquid conveying device, the device can simulate water jet cutting, gas pore pressure and separation of solid-liquid-gas three-phase mixed backflow liquid and other processes, meeting the all-round research needs of deep coal seam mining. The device integrates multiple experimental functions in one, can perform multiple simulation experiments at the same time, greatly improves the authenticity and comprehensiveness of the simulation of actual coal and coalbed methane mining, and improves the simulation experiment efficiency. At the same time, the ingenious connection design between each device facilitates experimental operation and maintenance. The device can not only be used for deep coal seam mining research, but also can be applied to other related fields such as underground resource development and geological disaster prediction, and has wide application prospects.

[0122] The deep coal seam high pressure jet breaking physical fluidization mining simulation device of the present application can be used to simulate the 1500-2500m deep coal and coalbed methane occurrence environment, and carry out high pressure water jet cutting and cavity forming physical fluidization mining simulation experiment. The triaxial compression testing device provided by the present application can apply axial and radial pressure, and the radial confining pressure can be provided by a confining pressure pump to 60Mpa. The gas pressurizing device is designed to apply gas pore pressure to the coal rock, which can reach 30MPa at the highest. The temperature heating device can continuously heat the oil around the sample to simulate the actual deep high temperature environment. To enhance the effect of deep formation hydraulic cutting and pressure relief, the present application proposes to move the nozzle by moving the oil pipe axially and rotating radially, so as to achieve better cutting and pressure relief effect, and to form a cavity on the coal seam, so that the coal and coalbed methane broken by the hydraulic jet flow out of the wellbore with the fluid, realizing the fluidization mining of deep coal resources, and designing a three-phase solid-liquid separator at the wellhead to separate different mineral resources. In the field of deep coal seam fluidization mining technology, it has popularization and application value.

[0123] The present application can simulate the complex pressure environment of deep underground coal rock by applying axial pressure, axial counterforce and confining pressure to the coal rock sample through the three-axis pressure experimental device and applying pore pressure through the gas pressure device, thereby improving the accuracy and reliability of the simulation experiment. The coal rock sample can be cut through the water jet cutting experimental device, the water jet cutting process in the actual mining process can be simulated, and the influence of the water jet cutting on the coal rock crushing and the coal bed gas release can be studied. The three-phase mixed reflux liquid separation device is arranged, the flow state liquid mixture obtained by cutting flows into the three-phase reflux liquid conveying device through the sleeve of the three-axis pressure experimental device, and is separated through the device, the treatment process of the solid-liquid-gas three-phase mixed reflux liquid in the actual mining process can be simulated, and the composition and properties of the reflux liquid can be studied, thereby providing an important basis for the co-mining of coal bed gas and coal. The present application combines the simulation device with the method of deep coal seam high pressure jet breaking physical fluidization coal and coal bed gas co-mining, proposes a new experimental method, provides a new idea and technical means for the related field research, can be widely applied to the co-mining research of coal bed gas and coal and the related fields of geology, mining, energy and the like, and has important practical value and application prospect.

[0124] The above examples are only preferred embodiments for fully illustrating the present application, and the protection scope of the present application is not limited thereto. The equivalent replacement or transformation of the skilled in the art on the basis of the present application is within the protection scope of the present application.

Claims

1. A deep coal seam high pressure jet breaking physical fluidization mining simulation device, characterized in that, The utility model relates to a three-phase backflow liquid conveying device connected with the triaxial pressure experiment device for simulating the separation of solid-liquid-gas three-phase mixed backflow liquid. The triaxial pressure experiment device comprises: An experimental box (2) for accommodating a coal rock sample (1); A jacking hydraulic cylinder (3) arranged at the bottom of the experimental box (2) for providing axial pressure; A door-shaped counterforce frame (4) arranged at the top of the experimental box (2) for providing axial counterforce; A confining pressure pump (5) connected with the experimental box (2) for providing confining pressure. The hydraulic slotting experiment device comprises: A sleeve (10) arranged through a mounting hole (201) of the experimental box (2) and extending into the wellhead of the coal rock sample (1); An oil pipe (11) arranged in the sleeve (10); One end of the oil pipe (11) is connected with a rotary joint (12), a valve (13), a booster pump (14) and a water tank (15) in sequence; and / or an oil pipe centralizer (16) and a nozzle (17) are arranged on the oil pipe (11), and the nozzle (17) is located below the oil pipe centralizer (16); A slide rail (18) is arranged on the inner wall of the sleeve (10), and the nozzle (17) is in sliding fit with the slide rail (18). The experimental box (2) is provided with: A mounting hole (201) for mounting the hydraulic slotting experiment device; An oil inlet (202) connected with the confining pressure pump (5) through a high-pressure oil pipe (6); A wire inlet (203) connected with a heating device (7) through a wire for simulating the high-temperature state of deep underground coal rock; 2. The deep coal seam high pressure jet breaking physical fluidization mining simulation device and method according to claim 1, characterized in that, A gas inlet (204) for mounting the gas pressurizing device; And / or a mounting seat (8) is further arranged between the experimental box (2) and the jacking hydraulic cylinder (3); And / or the jacking hydraulic cylinder (3) is connected with a hydraulic servo controller (9). The three-phase backflow liquid conveying device comprises: A backflow liquid pipeline (19) with one end connected with the sleeve (10); A three-phase solid-liquid-gas separation device connected with the other end of the backflow liquid pipeline (19). The three-phase solid-liquid-gas separation device comprises:

3. The deep coal seam high pressure jet breaking and physical fluidization mining simulation device according to claim 1, characterized in that, A fairing (28), an exhaust pipe (29) arranged in the fairing (28), and a reflecting disc (30) arranged on the exhaust pipe (29) and located in the fairing (28); The fairing (28) is provided with a liquid discharge port (281) and a solid discharge port (282), and a screen (31) is arranged at the liquid discharge port (281). The gas pressurizing device comprises:

4. The deep coal seam high pressure jet breaking physical fluidization mining simulation device according to claim 3, characterized in that, An upper pressure head (20) arranged at the gas inlet (204) at the top of the experimental box (2); ​ 5. The deep coal seam high pressure jet breaking physical fluidization mining simulation device according to claim 1, characterized in that, ​ ​ A lower pressing head (21) is arranged at a gas inlet (204) at the bottom of the experimental box (2); A flow guide pipe (22) is connected to a high-pressure gas cylinder (23) at one end and to the upper pressing head (20) and / or the lower pressing head (21) at the other end.

6. The deep-seam high-pressure jet fragmentation physical fluidization mining simulation device according to claim 1, characterized in that, The deep underground coal rock has a depth of 1500-2500 meters; And / or, the simulation device can provide a confining pressure of 60 MPa, a temperature of 120℃ and a pore pressure of 30 MPa; And / or, the wellbore of the simulation device can withstand a pressure of 80 MPa, and the wellhead can withstand a pressure of 100 MPa.

7. A method for co-mining physical fluidized coal and coal bed gas by high pressure jet breaking in deep coal seam using the simulation device according to any one of claims 1 to 6, characterized in that, The method comprises the following steps: The coal rock sample is placed in the experimental box of the triaxial compression testing device, the triaxial compression testing device is used to apply axial pressure, axial counterforce and confining pressure to the coal rock sample to simulate the triaxial pressure of the deep underground coal rock, the gas pressurizing device is used to apply pore pressure to the coal rock sample to simulate the pore pressure of the deep underground coal rock, the hydraulic slotting device is used to cut the coal rock sample to simulate hydraulic slotting, the flow state liquid mixture obtained by cutting is flowed into the three-phase backflow liquid conveying device through the casing of the triaxial compression testing device, and the flow state liquid mixture is separated by the three-phase backflow liquid conveying device to simulate the separation of the solid-liquid-gas three-phase mixed backflow liquid.

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