Coal mine underground complex stratum gas-liquid double-circulation directional drilling system and method

Abstract

The invention discloses a coal mine underground complex stratum gas-liquid double-circulation directional drilling system and method.The coal mine underground complex stratum gas-liquid double-circulation directional drilling system comprises a directional drill bit, a double-wall hollow liquid drive screw drill, a three-channel instrument outer pipe, a three-channel drill rod and a three-channel water tank which are connected in sequence, and the front end of the double-wall hollow liquid drive screw drill is connected with the directional drill bit; a center channel of the double-wall hollow hydraulic drive screw drill is a high-pressure air or nitrogen channel and is communicated with a directional drill bit air hole, a stator and rotor annular channel is a high-pressure water inlet channel, and a stator rod body and screw drill outer pipe annular channel is a high-pressure water return channel. A central channel of the three-channel instrument outer pipe, the three-channel drill rod and the three-channel water tank is a high-pressure air or nitrogen inlet channel, a middle annular channel is a high-pressure water inlet channel, and an outer annular channel is a high-pressure water return channel. The hydraulic directional drilling device has the remarkable advantages that the hydraulic directional drilling torque is large, the rock stratum drilling efficiency is high, the pore-forming capacity of a complex broken stratum can be improved through air deslagging, cyclic utilization of directional drilling water can be achieved, and water resources are saved.

Description

Technical Field

[0001] The invention belongs to the technical field of coal mine drilling, and relates to a complex stratum directional drilling method, and specifically to a complex stratum gas-liquid dual circulation directional drilling system and a directional drilling process method. Background Art

[0002] The near-horizontal directional drilling technology in underground coal mines has been widely used in drilling construction such as gas control, water hazard prevention and control, and detection of hidden disaster factors in underground coal mines due to its advantages such as artificially controllable drilling trajectory, high construction accuracy, and large single-hole coverage, and has achieved remarkable application results. At present, the underground directional drilling technology in coal mines mainly includes hydraulic directional drilling technology and pneumatic directional drilling technology. Among them, the hydraulic directional drilling technology uses high-pressure water to drive the screw drill for drilling, which has the advantage of high output torque and is suitable for rock formations with a hardness coefficient of less than 10 and hard coal formations with a hardness coefficient of more than 0.8. However, for complex formation conditions, such as unstable formations such as mudstone and sandy mudstone, geological structures such as faults, folds, and collapse columns, and broken soft coal formations, the hole wall is prone to instability under the scouring effect of high-pressure water during drilling, and the hole collapses seriously, making it difficult to form a hole. Therefore, it is not suitable for drilling in the above-mentioned complex formation conditions; at the same time, the hydraulic directional drilling technology requires a large amount of water for construction, and the general water supply requirement is not less than 20m 3 / h, the drilling water is not recycled, resulting in serious waste of water resources. This drilling process cannot be used in coal mines in areas with severe water shortages. The pneumatic directional drilling process uses high-pressure gas to drive the screw drill for drilling. Since gas is used as the slag removal medium, gas slag removal has the advantage of little disturbance to the hole wall. This process has good hole-forming ability under complex formation conditions. It is currently mainly suitable for broken soft coal seams with a hardness coefficient of 0.3-0.8. However, due to the compressible characteristics of the gas itself, as well as the low output gas pressure of the air compressor and nitrogen generator used in coal mines, the output torque of the pneumatic screw drill is low. This process is not suitable for rock drilling. When encountering the top and bottom plates of the coal seam or gangue in the coal seam during drilling, the drilling efficiency is extremely low. In severe cases, it is difficult to drill, resulting in low drilling construction efficiency. In severe cases, the designed hole depth requirements cannot be met. Summary of the invention

[0003] In view of the shortcomings existing in the prior art, the purpose of the present invention is to provide a gas-liquid dual-circulation directional drilling system and method for complex strata in underground coal mines, so as to solve the problems in the prior art that the hydraulic directional drilling process in complex strata conditions has serious hole collapse and difficulty in drilling, and the hydraulic directional drilling process has high water supply requirements and no recycling, and the pneumatic directional drilling process has extremely low drilling efficiency or even difficulty in drilling in rock strata.

[0004] In order to solve the above technical problems, the present invention adopts the following technical solutions to achieve the above problems:

[0005] Gas-liquid dual-circulation directional drilling system for complex formations in underground coal mines, including a directional drill bit, a double-walled hollow liquid-driven screw drill, a three-channel instrument outer tube, a three-channel drill rod and a three-channel water stool connected in sequence;

[0006] The double-walled hollow liquid-driven screw drill comprises a hollow rotor, a universal shaft and a transmission shaft connected in sequence, and also comprises a stator sleeved outside the rotor, a stator rod body arranged outside the stator, and a screw drill outer tube sleeved outside the stator rod body; the three-channel instrument outer tube comprises an inner tube, an intermediate tube and an outer tube sleeved in sequence from the inside to the outside; the three-channel drill pipe comprises an inner drill pipe tube, an intermediate drill pipe tube and an outer drill pipe tube sleeved in sequence from the inside to the outside; the three-channel water stool comprises an inner water stool tube, an intermediate water stool tube and an outer water stool tube sleeved in sequence from the inside to the outside;

[0007] The transmission shaft, universal shaft, rotor, inner tube, drill pipe inner tube and water toilet inner tube are connected in sequence from front to back and connected to form a central channel. The front end of the central channel is connected to the air eye of the directional drill bit, and the rear end of the central channel is a high-pressure hose joint to connect with an air compressor or a nitrogen generator; the stator and stator rod body, intermediate tube, drill pipe intermediate tube and water toilet intermediate tube are connected in sequence and connected to form an intermediate annulus channel. The front end of the intermediate annulus channel is sealed by a seal, and the rear end of the intermediate annulus channel is connected to a high-pressure hose joint to connect with a mud pump; the screw drill tool outer tube, outer tube, drill pipe outer tube and water toilet outer tube are connected in sequence and connected to form an outer annulus channel. The front end of the outer annulus channel is sealed and connected to the intermediate annulus channel through the water eye on the front end side wall of the stator rod body, and the rear end of the outer annulus channel is connected to a high-pressure hose joint to connect with a water tank.

[0008] The present invention also includes the following technical features:

[0009] Specifically, the rear end of the rotor is a male joint and is plugged into the female joint at the front end of the inner tube, the rear end of the stator rod body is a female joint and is plugged into the male joint at the front end of the intermediate tube, and the rear end of the outer tube of the screw drill is a female buckle and is threadedly connected to the male buckle at the front end of the outer tube.

[0010] Specifically, the rear end of the inner tube is a male joint and is plugged into the front end female joint of the inner tube of the drill pipe, the rear end of the middle tube is a female joint and is plugged into the front end male joint of the middle tube of the drill pipe, and the rear end of the outer tube is a female buckle and is connected to the front end male buckle of the outer tube of the drill pipe by threaded connection.

[0011] Specifically, the rear end of the drill pipe inner tube is a male joint and is plugged into the front end female joint of the water toilet inner tube, the rear end of the drill pipe middle tube is a female joint and is plugged into the front end male joint of the water toilet middle tube, and the rear end of the drill pipe outer tube is a female buckle and is connected to the front end male buckle of the water toilet outer tube by threaded connection.

[0012] Specifically, a sealing ring is provided between the rear outer wall of the inner water toilet tube and the annular boss on the inner wall of the rear end inner wall of the middle water toilet tube; a sealing ring is provided between the rear outer wall of the middle water toilet tube and the annular boss on the inner wall of the rear end inner wall of the outer water toilet tube; bearing assemblies are installed between the inner water toilet tube and the middle water toilet tube, and between the middle water toilet tube and the outer water toilet tube, so that the inner water toilet tube, the middle water toilet tube and the outer water toilet tube can rotate relative to each other.

[0013] Specifically, a connecting hole is provided in the rear side wall of the inner pipe of the water toilet, and the connecting hole connects the middle annular channel and the high-pressure hose joint; a connecting hole is provided in the rear side wall of the middle pipe of the water toilet, and the connecting hole connects the outer annular channel and the high-pressure hose joint.

[0014] Specifically, a measurement while drilling instrument assembly is arranged in the central channel corresponding to the three-channel instrument outer tube.

[0015] Specifically, the central channel is a channel for compressed air or nitrogen to enter, the middle annular channel is a channel for high-pressure water to enter, and the outer annular channel is a channel for high-pressure water to return; high-pressure water enters from the middle annular channel to drive the rotor of the double-walled hollow liquid-driven screw drill to rotate, driving the directional drill bit to rotate and break rocks for drilling, and then returns from the outer annular channel to enter the water tank; compressed air or nitrogen enters the directional drill bit eye through the central channel to cool the directional drill bit and carry drill cuttings, and then returns to the outside of the hole through the directional drill bit and the hole wall annular channel.

[0016] Specifically, the high-pressure water enters from the middle annulus channel to drive the double-wall hollow liquid-driven screw drill rotor to rotate, then returns from the outer annulus channel into the water tank, and is then sucked into the middle annulus channel by the mud pump, thereby realizing the recycling of high-pressure water.

[0017] The method for directional drilling by the gas-liquid dual circulation directional drilling system in a complex underground coal mine formation comprises the following steps:

[0018] Step 1: Connect the directional drill bit, double-wall hollow liquid-driven screw drill bit, three-channel instrument outer tube, three-channel drill pipe and three-channel water stool in sequence;

[0019] Step 2: The central channel of the three-channel water stool is connected to the air compressor or nitrogen generator through a high-pressure hose, the middle annulus channel of the three-channel water stool is connected to the mud pump through a high-pressure hose, and the outer annulus channel of the three-channel water stool is connected to the water tank through a high-pressure hose;

[0020] Step 3: Start the mud pump, air compressor or nitrogen generator to supply high-pressure water and high-pressure air or nitrogen to the directional drilling tool respectively. The high-pressure air or nitrogen returns to the outside of the hole from the directional drilling tool and the hole wall annulus channel, and the high-pressure water returns to the water tank from the outer annulus channel. The high-pressure water is recycled;

[0021] Step 4: Start the directional drilling rig, rotate the directional drilling tool to adjust the tool face angle, push the directional drilling tool forward through the directional drilling rig, and drive the directional drill bit forward. The double-wall hollow liquid-driven screw drilling tool drives the directional drill bit to rotate and break the rock, realizing sliding directional drilling;

[0022] Step 5: When the three-channel drill pipe of the directional drill is finished drilling, turn off the mud pump, turn off the air compressor or nitrogen generator, remove the three-channel water stool, use the drilling measurement instrument to measure the drilling trajectory, connect the three-channel drill pipe, and then connect the three-channel water stool;

[0023] Step 6: Repeat steps 3, 4 and 5 to complete the directional drilling construction.

[0024] Compared with the prior art, the present invention has the following technical effects:

[0025] The present invention adopts a gas-liquid dual circulation system. On the one hand, it uses high-pressure water to drive the screw drill to drive the directional drill bit to rotate and break rocks, giving full play to the advantage of the large output torque of the hydraulic screw drill, which can meet the needs of efficient directional drilling of rock formations. On the other hand, it uses high-pressure gas to discharge slag, giving full play to the advantage of the small disturbance of the gas on the hole wall, which can meet the needs of drilling holes in unstable areas such as broken soft coal seams, mudstone, sandy mudstone and other unstable formations, faults, collapse columns and other geological structures. At the same time, the present invention realizes the recycling of high-pressure water for directional drilling, saves water resources, and can be applied to underground drilling construction in coal mines where water resources are extremely scarce. In summary, the system method of the present invention can solve the technical problems of unstable formation collapse in hydraulic directional drilling under complex formation conditions and extremely low drilling efficiency in rock formations by pneumatic directional drilling, greatly broadening the scope of applicable formation conditions for directional drilling technology. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 It is a schematic diagram of the structure of the gas-liquid dual circulation directional drilling system for complex formations in underground coal mines of the present invention;

[0027] Figure 2 It is a schematic diagram of the structure of the double-walled hollow liquid-driven screw drill tool of the present invention;

[0028] Figure 3 It is a schematic diagram of the outer tube structure of the three-channel instrument of the present invention;

[0029] Figure 4 It is a schematic diagram of the three-channel drill rod structure of the present invention;

[0030] Figure 5 It is a schematic diagram of the three-channel water stool structure of the present invention.

[0031] The meaning of each number in the figure is:

[0032] 1. Directional drill bit, 2. Double-walled hollow liquid-driven screw drill, 3. Three-channel instrument outer tube, 4. Three-channel drill pipe, 5. Three-channel water stool, 6. Air compressor or nitrogen generator, 7. Mud pump, 8. Water tank, 9. High-pressure hose;

[0033] 2-1. Transmission shaft, 2-2. Seal, 2-3. Universal joint, 2-4. Water eye, 2-5. Rotor, 2-6. Stator, 2-7. Stator rod, 2-8. Outer tube of screw drill;

[0034] 3-1. Inner tube, 3-2. Intermediate tube, 3-3. Outer tube, 3-4. Measuring instrument assembly;

[0035] 4-1. Drill pipe inner tube, 4-2. Drill pipe middle tube, 4-3. Drill pipe outer tube;

[0036] 5-1. Inner pipe of toilet, 5-2. Middle pipe of toilet, 5-3. Outer pipe of toilet, 5-4. High pressure hose joint;

[0037] 10. Center channel, 20. Middle annulus channel, 30. Outer annulus channel. DETAILED DESCRIPTION

[0038] Specific embodiments of the present invention are given below. It should be noted that the present invention is not limited to the following specific embodiments, and all equivalent changes made on the basis of the technical solution of this application fall within the protection scope of the present invention.

[0039] Embodiment 1:

[0040] like Figures 1 to 5 As shown, this embodiment provides a gas-liquid dual-circulation directional drilling system for complex formations in underground coal mines, including a directional drill bit 1, a double-walled hollow liquid-driven screw drill bit 2, a three-channel instrument outer tube 3, a three-channel drill rod 4 and a three-channel water stool 5 connected in sequence.

[0041] The double-walled hollow liquid-driven screw drilling tool 2 includes a hollow rotor 2-5, a universal joint 2-3 and a transmission shaft 2-1 connected in sequence, and also includes a stator 2-6 sleeved outside the rotor 2-5, a stator rod body 2-7 arranged outside the stator 2-6, and a screw drilling tool outer tube 2-8 sleeved outside the stator rod body 2-7; the three-channel instrument outer tube 3 includes an inner tube 3-1, an intermediate tube 3-2 and an outer tube 3-3 sequentially sleeved from the inside to the outside; the three-channel drill pipe 4 includes a drill pipe inner tube 4-1, a drill pipe intermediate tube 4-2 and a drill pipe outer tube 4-3 sequentially sleeved from the inside to the outside; the three-channel water stool 5 includes a water stool inner tube 5-1, a water stool intermediate tube 5-2 and a water stool outer tube 5-3 sequentially sleeved from the inside to the outside.

[0042] The transmission shaft 2-1, the universal shaft 2-3, the rotor 2-5, the inner tube 3-1, the drill pipe inner tube 4-1 and the water stool inner tube 5-1 are connected in sequence from front to back and connected to form a central channel 10. The front end of the central channel 10 is connected to the wind eye of the directional drill bit 1, and the rear end of the central channel 10 is a high-pressure hose connector 5-4 to connect with the air compressor or nitrogen generator 6; the stator 2-6 and the stator rod body 2-7, the intermediate tube 3-2, the drill pipe intermediate tube 4-2 and the water stool intermediate tube 5-2 are connected in sequence and connected to form an intermediate annulus channel 20. The front end of the intermediate annulus channel 20 is sealed by a seal 2-2, and the rear part of the intermediate annulus channel 20 is connected to the high-pressure hose joint 5-4 to be connected to the mud pump 7; the screw drill tool outer tube 2-8, the outer tube 3-3, the drill pipe outer tube 4-3 and the water pipe outer tube 5-3 are connected in sequence and connected to form an outer annulus channel 30, the front end of the outer annulus channel 30 is sealed and connected to the intermediate annulus channel 20 through the water hole 2-4 on the front end side wall of the stator rod body 2-7, and the rear part of the outer annulus channel 30 is connected to the high-pressure hose joint 5-4 to be connected to the water tank 8.

[0043] The rear end of the rotor 2-5 is a male joint and is plugged into the front female joint of the inner tube 3-1. The rear end of the stator rod body 2-7 is a female joint and is plugged into the front male joint of the intermediate tube 3-2. The rear end of the screw drill outer tube 2-8 is a female buckle and is connected to the front male buckle of the outer tube 3-3 by threaded connection.

[0044] The rear end of the inner tube 3-1 is a male joint and is plugged into the front end female joint of the drill pipe inner tube 4-1. The rear end of the intermediate tube 3-2 is a female joint and is plugged into the front end male joint of the drill pipe intermediate tube 4-2. The rear end of the outer tube 3-3 is a female buckle and is connected to the front end male buckle of the drill pipe outer tube 4-3 by threaded connection.

[0045] The rear end of the drill pipe inner tube 4-1 is a male joint and is plugged into the front end female joint of the water toilet inner tube 5-1. The rear end of the drill pipe intermediate tube 4-2 is a female joint and is plugged into the front end male joint of the water toilet intermediate tube 5-2. The rear end of the drill pipe outer tube 4-3 is a female buckle and is connected to the front end male buckle of the water toilet outer tube 5-3 with a threaded connection.

[0046] A sealing ring is provided between the rear outer wall of the toilet inner pipe 5-1 and the annular boss on the rear inner wall of the toilet intermediate pipe 5-2; a sealing ring is provided between the rear outer wall of the toilet intermediate pipe 5-2 and the annular boss on the rear inner wall of the toilet outer pipe 5-3. Bearing assemblies are installed between the toilet inner pipe 5-1 and the toilet intermediate pipe 5-2, and between the toilet intermediate pipe 5-2 and the toilet outer pipe 5-3, so that the toilet inner pipe 5-1, the toilet intermediate pipe 5-2 and the toilet outer pipe 5-3 can rotate relative to each other.

[0047] A connecting hole is provided in the rear side wall of the water toilet inner pipe 5-1, which connects the middle annular passage 20 with the high-pressure hose joint 5-4; a connecting hole is provided in the rear side wall of the water toilet middle pipe 5-2, which connects the outer annular passage 30 with the high-pressure hose joint 5-4.

[0048] A measurement while drilling instrument assembly 3 - 4 is arranged in the central channel 10 corresponding to the three-channel instrument outer tube 3 .

[0049] The central passage 10 and the intermediate annular passage 20 have a single-action function.

[0050] Seals 2-2 are provided at the front and rear of the transmission shaft 2-1.

[0051] The central channel 10 is the channel for compressed air or nitrogen to enter, the middle annular channel 20 is the channel for high-pressure water to enter, and the outer annular channel 30 is the channel for high-pressure water to return; high-pressure water enters from the middle annular channel 20 to drive the rotor 2-5 of the double-walled hollow liquid-driven screw drilling tool 2 to rotate, driving the directional drill bit 1 to rotate and break rocks for drilling, and then returns from the outer annular space to enter the water tank 8; compressed air or nitrogen enters the wind eye of the directional drill bit 1 through the central channel 10, cools the directional drill bit 1 and carries drill cuttings, and then returns to the outside of the hole through the directional drilling tool and the hole wall annular channel.

[0052] High-pressure water enters from the middle annular passage 20 to drive the rotor 2-5 of the double-walled hollow liquid-driven screw drilling tool 2 to rotate, then returns from the outer annular passage 30 to enter the water tank 8, and is then sucked into the middle annular passage 20 by the mud pump 7, thereby realizing the recycling of high-pressure water.

[0053] Embodiment 2:

[0054] This embodiment provides a method for directional drilling in a gas-liquid dual circulation directional drilling system for complex formations in underground coal mines. During directional drilling, high-pressure water generated by a mud pump passes through the middle annular channel and enters the double-walled hollow liquid-driven screw drill to drive the rotor to rotate, driving the directional drill bit to rotate and crush rocks. The high-pressure water then returns through the outer annular channel, enters the water tank through a high-pressure hose connected to the three-channel water outlet, and is pressurized by the mud pump again to enter the middle annular channel, thus realizing the recycling and reuse of high-pressure water. The high-pressure air or nitrogen generated by the air compressor or nitrogen generator enters the bottom of the hole through the central channel to the directional drill bit wind eye, cools the drill bit, and at the same time, the drill cuttings formed by the directional drill bit breaking the rock are discharged out of the hole through the directional drilling tool and the hole wall annular channel. Finally, a gas-liquid dual circulation directional drilling process method is formed in which high-pressure water drives the double-walled hollow liquid-driven screw drill to drive the directional drill bit to rotate and crush rocks, and high-pressure air or nitrogen is used to discharge slag. This method has the significant advantages of large hydraulic directional drilling torque, high rock drilling efficiency, and air deslagging to improve the hole-forming capacity of complex broken formations. At the same time, this method realizes the recycling of directional drilling water and saves water resources.

[0055] The specific steps include:

[0056] Step 1: Connect the directional drill bit, double-wall hollow liquid-driven screw drill bit, three-channel instrument outer tube, three-channel drill pipe and three-channel water stool in sequence;

[0057] Step 2: The central channel of the three-channel water stool is connected to the air compressor or nitrogen generator through a high-pressure hose, the middle annulus channel of the three-channel water stool is connected to the mud pump through a high-pressure hose, and the outer annulus channel of the three-channel water stool is connected to the water tank through a high-pressure hose;

[0058] Step 3: Start the mud pump, air compressor or nitrogen generator to supply high-pressure water and high-pressure air or nitrogen to the directional drilling tool respectively. The high-pressure air or nitrogen returns to the outside of the hole from the directional drilling tool and the hole wall annulus channel, and the high-pressure water returns to the water tank from the outer annulus channel. The high-pressure water is recycled;

[0059] Step 4: Start the directional drilling rig, rotate the directional drilling tool to adjust the tool face angle, push the directional drilling tool forward through the directional drilling rig, and drive the directional drill bit forward. The double-wall hollow liquid-driven screw drilling tool drives the directional drill bit to rotate and break the rock, realizing sliding directional drilling;

[0060] Step 5: When the three-channel drill pipe of the directional drill is finished drilling, turn off the mud pump, turn off the air compressor or nitrogen generator, remove the three-channel water stool, use the drilling measurement instrument to measure the drilling trajectory, connect the three-channel drill pipe, and then connect the three-channel water stool;

[0061] Step 6: Repeat steps 3, 4 and 5 to complete the directional drilling construction.

[0062] The present invention adopts a gas-liquid dual circulation system. On the one hand, it uses high-pressure water to drive the screw drill to drive the directional drill bit to rotate and break rocks, giving full play to the advantage of the large output torque of the hydraulic screw drill, which can meet the needs of efficient directional drilling of rock formations. On the other hand, it uses high-pressure gas to discharge slag, giving full play to the advantage of the small disturbance of the gas on the hole wall, which can meet the needs of drilling holes in unstable areas such as broken soft coal seams, mudstone, sandy mudstone and other unstable formations, faults, collapse columns and other geological structures. At the same time, the present invention realizes the recycling of high-pressure water for directional drilling, saves water resources, and can be applied to underground drilling construction in coal mines where water resources are extremely scarce. In summary, the system method of the present invention can solve the technical problems of unstable formation collapse in hydraulic directional drilling under complex formation conditions and extremely low drilling efficiency in rock formations by pneumatic directional drilling, greatly broadening the scope of applicable formation conditions for directional drilling technology.

[0063] The preferred embodiments of the present invention are described in detail above in conjunction with the accompanying drawings. However, the present invention is not limited to the specific details in the above embodiments. Within the technical concept of the present invention, a variety of simple modifications can be made to the technical solution of the present invention, and these simple modifications all belong to the protection scope of the present invention.

[0064] It should also be noted that the various specific technical features described in the above specific embodiments can be combined in any suitable manner without contradiction. In order to avoid unnecessary repetition, the present invention will not further describe various possible combinations.

[0065] In addition, various embodiments of the present invention may be arbitrarily combined, and as long as they do not violate the concept of the present invention, they should also be regarded as the contents disclosed by the present invention.

Claims

1. Gas-liquid dual circulation directional drilling system for complex formations in coal mines. It is characterized in that It comprises a directional drill bit (1), a double-walled hollow liquid-driven screw drill (2), a three-channel instrument outer tube (3), a three-channel drill rod (4) and a three-channel water stool (5) which are connected in sequence; The double-walled hollow liquid-driven screw drill (2) comprises a hollow rotor (2-5), a universal shaft (2-3) and a transmission shaft (2-1) connected in sequence, and also comprises a stator (2-6) sleeved outside the rotor (2-5), a stator rod body (2-7) arranged outside the stator (2-6), and a screw drill outer tube (2-8) sleeved outside the stator rod body (2-7); the three-channel instrument outer tube (3) comprises an inner tube (3-1), an intermediate tube (3-2) and an outer tube (3-3) sleeved in sequence from the inside to the outside; the three-channel drill rod (4) comprises a drill rod inner tube (4-1), a drill rod intermediate tube (4-2) and a drill rod outer tube (4-3) sleeved in sequence from the inside to the outside; the three-channel water stool (5) comprises a water stool inner tube (5-1), a water stool intermediate tube (5-2) and a water stool outer tube (5-3) sleeved in sequence from the inside to the outside; The transmission shaft (2-1), the universal shaft (2-3), the rotor (2-5), the inner tube (3-1), the drill pipe inner tube (4-1) and the water pipe inner tube (5-1) are connected in sequence from front to back and connected to form a central channel (10); the front end of the central channel (10) is connected to the wind eye of the directional drill bit (1), and the rear end of the central channel (10) is a high-pressure hose joint (5-4) for connecting to an air compressor or a nitrogen generator (6); the stator (2-6) and the stator rod body (2-7), the intermediate tube (3-2), the drill pipe intermediate tube (4-2) and the water pipe intermediate tube (5-2) are connected in sequence and connected to form an intermediate annular channel (20). The front end of the intermediate annular passage (20) is sealed by a sealing member (2-2), and the rear end of the intermediate annular passage (20) is connected to a high-pressure hose joint (5-4) to be connected to a mud pump (7); the screw drill tool outer tube (2-8), the outer tube (3-3), the drill pipe outer tube (4-3) and the water pipe outer tube (5-3) are sequentially connected and connected to form an outer annular passage (30), the front end of the outer annular passage (30) is sealed and is connected to the intermediate annular passage (20) through a water hole (2-4) on the front end side wall of the stator rod body (2-7), and the rear end of the outer annular passage (30) is connected to a high-pressure hose joint (5-4) to be connected to a water tank (8).

2. The gas-liquid dual circulation directional drilling system for complex formations in underground coal mines as claimed in claim 1, It is characterized in that The rear end of the rotor (2-5) is a male joint and is plugged into the front end female joint of the inner tube (3-1); the rear end of the stator rod body (2-7) is a female joint and is plugged into the front end male joint of the intermediate tube (3-2); the rear end of the screw drill tool outer tube (2-8) is a female buckle and is threadedly connected to the front end male buckle of the outer tube (3-3).

3. The gas-liquid dual circulation directional drilling system for complex formations in underground coal mines as claimed in claim 1, It is characterized in that The rear end of the inner tube (3-1) is a male joint and is plugged into the front end female joint of the drill rod inner tube (4-1); the rear end of the intermediate tube (3-2) is a female joint and is plugged into the front end male joint of the drill rod intermediate tube (4-2); the rear end of the outer tube (3-3) is a female buckle and is connected to the front end male buckle of the drill rod outer tube (4-3) by threaded connection.

4. The gas-liquid dual circulation directional drilling system for complex formations in underground coal mines as claimed in claim 1, It is characterized in that The rear end of the drill rod inner tube (4-1) is a male joint and is plugged into the front end female joint of the toilet inner tube (5-1); the rear end of the drill rod intermediate tube (4-2) is a female joint and is plugged into the front end male joint of the toilet intermediate tube (5-2); the rear end of the drill rod outer tube (4-3) is a female buckle and is connected to the front end male buckle of the toilet outer tube (5-3) by threaded connection.

5. The gas-liquid dual circulation directional drilling system for complex formations in underground coal mines as claimed in claim 1, It is characterized in that A sealing ring is provided between the rear outer wall of the inner water pipe (5-1) and the annular boss on the rear inner wall of the middle water pipe (5-2); a sealing ring is provided between the rear outer wall of the middle water pipe (5-2) and the annular boss on the rear inner wall of the outer water pipe (5-3); and bearing assemblies are installed between the inner water pipe (5-1) and the middle water pipe (5-2), and between the middle water pipe (5-2) and the outer water pipe (5-3), so that the inner water pipe (5-1), the middle water pipe (5-2) and the outer water pipe (5-3) can rotate relative to each other.

6. The gas-liquid dual circulation directional drilling system for complex formations in underground coal mines as claimed in claim 1, It is characterized in that A connecting hole is provided in the rear side wall of the toilet inner pipe (5-1), and the connecting hole connects the middle annular passage (20) and the high-pressure hose joint (5-4); a connecting hole is provided in the rear side wall of the toilet middle pipe (5-2), and the connecting hole connects the outer annular passage (30) and the high-pressure hose joint (5-4).

7. The gas-liquid dual circulation directional drilling system for complex formations in underground coal mines as claimed in claim 1, It is characterized in that A measurement while drilling instrument assembly (3-4) is arranged in the central channel (10) corresponding to the three-channel instrument outer tube (3).

8. The gas-liquid dual circulation directional drilling system for complex formations in underground coal mines as claimed in claim 1, It is characterized in that The central channel (10) is a channel for compressed air or nitrogen to enter, the middle annular channel (20) is a channel for high-pressure water to enter, and the outer annular channel (30) is a channel for high-pressure water to return; the high-pressure water enters from the middle annular channel (20) to drive the rotor (2-5) of the double-wall hollow liquid-driven screw drill (2) to rotate and drive the directional drill bit (1) to rotate and break rocks for drilling, and then returns from the outer annular channel to enter the water tank (8); the compressed air or nitrogen enters the wind eye of the directional drill bit (1) through the central channel (10) to cool the directional drill bit (1) and carry drill cuttings, and then returns to the outside of the hole through the directional drill bit and the hole wall annular channel.

9. The gas-liquid dual circulation directional drilling system for complex formations in underground coal mines as claimed in claim 1, It is characterized in that The high-pressure water enters through the middle annular passage (20) to drive the rotor (2-5) of the double-walled hollow liquid-driven screw drill (2) to rotate, then returns through the outer annular passage (30) to enter the water tank (8), and is then sucked into the middle annular passage (20) by the mud pump (7), thereby realizing the recycling of the high-pressure water.

10. A method for directional drilling using the gas-liquid dual circulation directional drilling system for complex formations in underground coal mines according to claim 1, It is characterized in that The following steps are involved: Step 1: Connect the directional drill bit, double-wall hollow liquid-driven screw drill bit, three-channel instrument outer tube, three-channel drill pipe and three-channel water stool in sequence; Step 2: The central channel of the three-channel water stool is connected to the air compressor or nitrogen generator through a high-pressure hose, the middle annulus channel of the three-channel water stool is connected to the mud pump through a high-pressure hose, and the outer annulus channel of the three-channel water stool is connected to the water tank through a high-pressure hose; Step 3: Start the mud pump, air compressor or nitrogen generator to supply high-pressure water and high-pressure air or nitrogen to the directional drilling tool respectively. The high-pressure air or nitrogen returns to the outside of the hole from the directional drilling tool and the hole wall annulus channel, and the high-pressure water returns to the water tank from the outer annulus channel. The high-pressure water is recycled; Step 4: Start the directional drilling rig, rotate the directional drilling tool to adjust the tool face angle, push the directional drilling tool forward through the directional drilling rig, and drive the directional drill bit forward. The double-wall hollow liquid-driven screw drilling tool drives the directional drill bit to rotate and break the rock, realizing sliding directional drilling; Step 5: When the three-channel drill pipe of the directional drill is finished drilling, turn off the mud pump, turn off the air compressor or nitrogen generator, remove the three-channel water stool, use the drilling measurement instrument to measure the drilling trajectory, connect the three-channel drill pipe, and then connect the three-channel water stool; Step 6: Repeat steps 3, 4 and 5 to complete the directional drilling construction.

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