A multi-medium reverse circulation drilling device and method for broken soft coal seams

Abstract

The present invention discloses a multi-medium reverse circulation drilling device for broken soft coal seams, which includes a double-wall drill pipe, with a drill bit and a double-channel air swivel connected to both ends respectively. The orifice of the borehole is sealed with an orifice seal, and the double-wall drill pipe is rotated by a driving member; a main medium passage is arranged on the orifice seal, and the main medium passage is communicated with the outer annulus of the double-wall drill pipe, and the main medium in the outer annulus is communicated with the central channel of the double-wall drill pipe through the drill bit and the first connecting member on the double-wall drill pipe; an auxiliary medium passage is arranged on the double-channel air swivel, and the auxiliary medium passage is communicated with the inner annulus of the double-wall drill pipe, and the auxiliary medium in the inner annulus is communicated with the outer annulus through the second connecting member on the double-wall drill pipe. The present invention can ensure the effective drilling of gas drainage wells or boreholes in broken soft or soft-hard composite coal seams in coal mines.

Description

Technical Field

[0001] The present invention relates to the technical field of drilling, in particular to a multi-medium reverse circulation drilling device and method for broken soft coal seams. Background Art

[0002] With the increase of coal mining depth, the drilling difficulty of gas drainage wells or boreholes in broken soft or soft-hard composite coal seams in coal mines has become a world-class problem in the industry. The industry mainly uses positive circulation drilling, and the drill cuttings are discharged in the annulus between the drill string and the borehole wall. The circulating medium is the compressed air centrally supplied by the surface compressed air station in the coal mine, and the maximum air pressure is 0.75 MPa. The drill string assembly is a combination of φ73mm triangular drill pipes (single pipe length 1.0m) and φ94mm three-wing concave bits. A simple dust-proof device is provided at the hole mouth. The soft-hard composite coal seam is generally soft, loose, and has poor stability, and the borehole wall is prone to collapse. The coal seam has extremely poor permeability, high gas content, and high pressure in the hole when gas is released. Under the working conditions in coal mines, when using short drill strings, the drill cuttings of nearly horizontal boreholes frequently precipitate on the lower wall of the borehole due to gravity. As the borehole depth increases, the precipitated drill cuttings increase, the frictional resistance gradually increases, and the compressed air energy is gradually consumed, resulting in poor drainage of the gas released in the coal seam, accumulation of power, and accidents such as borehole wall collapse, hole blockage, and drill string burying. When the drilling depth reaches more than 100 meters, it is difficult to discharge the drill cuttings from the borehole, the penetration rate slows down, and accidents such as borehole collapse and hole blockage often occur during the borehole construction process. When a large amount of gas is released, accidents such as borehole blowout, drill string jamming, and drill string breakage are likely to occur. As a result, the formed borehole depth is shallow and the hole formation rate is low. Most boreholes cannot reach the designed depth (the designed depth of the current coal seam gas drainage boreholes is generally between 120 meters and 150 meters), which seriously affects the borehole gas drainage rate. This has been a difficult problem to solve in the field of gas drainage borehole drilling for many years.

[0003] The current object of reverse circulation geological boreholes is mainly rock, and vertical boreholes are drilled. The drill cuttings precipitate at the bottom of the borehole under the influence of gravity. For the coal seam gas drainage boreholes in coal mines, the object of the borehole is the coal seam, and nearly horizontal boreholes are drilled. When using the reverse circulation drilling technology to drill the coal seam gas drainage boreholes in coal mines, both the object of the borehole and the borehole inclination change, and the stress state of the drill cuttings returning from the central channel of the drill string to the hole mouth will change. The drill cuttings precipitate on the lower wall of the borehole under the influence of gravity. The reverse circulation drilling technology in geological exploration is not applicable to the drilling of coal seam gas drainage boreholes.

[0004] Geological reverse circulation drilling is divided into hydraulic reverse circulation and air reverse circulation according to different circulating media (clear water and drilling fluid). In the current air reverse circulation test hole drilling for coal seam gas drainage in coal mines, the compressed air enters through a single channel in the inner annular space of the double-wall drill pipe. There is no circulating medium flowing in the outer annulus between the hole wall and the drill tool. A small part of the compressed air carries the drill cuttings and enters the outer annulus between the hole wall and the drill tool reversely, resulting in some drill cuttings accumulating under the hole wall. After a long time of accumulation, the frictional resistance gradually increases, and the outer wall of the drill tool is prone to heat due to friction, making the gas discharged from the coal seam not smooth, gathering to generate power, and causing accidents such as hole wall collapse, hole plugging, and drill pipe burying. Drawing on the research results of reverse circulation drilling technology in other fields and aiming at the special conditions of drilling in soft-hard composite coal seams in coal mines, a multi-medium reverse circulation drilling device and method for soft broken coal seams are proposed in the research on the formation mechanism of reverse circulation in coal seams. Summary of the Invention

[0005] The purpose of the present invention is to provide a multi-medium reverse circulation drilling device and method for soft broken coal seams to solve the problems existing in the above-mentioned prior art and to ensure the effective drilling of gas extraction wells or boreholes in soft broken or soft-hard composite coal seams in coal mines.

[0006] To achieve the above purpose, the present invention provides the following solution: The present invention provides a multi-medium reverse circulation drilling device for soft broken coal seams, including

[0007] A double-wall drill pipe, with a drill bit and a double-channel air swivel connected to both ends respectively. The hole mouth of the borehole is sealed with a hole mouth seal, and the double-wall drill pipe rotates through a driving member;

[0008] A main medium passage is arranged on the hole mouth seal. The main medium passage is connected to the outer annulus of the double-wall drill pipe, and the main medium in the outer annulus is connected to the central channel of the double-wall drill pipe through the drill bit and the first connecting member on the double-wall drill pipe;

[0009] An auxiliary medium passage is arranged on the double-channel air swivel. The auxiliary medium passage is connected to the inner annulus of the double-wall drill pipe, and the auxiliary medium in the inner annulus is connected to the outer annulus through the second connecting member on the double-wall drill pipe;

[0010] A hole protection medium passage is arranged on the auxiliary medium passage and the hole protection medium is connected to the inner annulus.

[0011] Further, the main medium passage includes a main medium pipe connected to the inside of the hole mouth seal. The medium inlet end of the main medium pipe is respectively connected to two main medium branch pipes. A main inlet compressed air valve and a main inlet water valve are respectively fixed on the two main medium branch pipes. The first connecting member is an external ejector fixed on the side wall of the double-wall drill pipe, and the second connecting member is an external injector fixed on the side wall of the double-wall drill pipe.

[0012] Furthermore, the auxiliary medium passage includes an auxiliary medium pipe connected to the dual-channel gas and water faucet, and the medium inlet end of the auxiliary medium pipe is connected to two auxiliary medium branch pipes, and the two auxiliary medium branch pipes are respectively fixed with an auxiliary air pressure valve and a secondary water inlet valve.

[0013] Furthermore, the wall protection medium passage includes a wall protection medium pipe connected to the auxiliary medium pipe, two pneumatic mixers are arranged outside the borehole, the discharge ends of the two pneumatic mixers are connected to the wall protection medium pipe through a pneumatic grouting pump, and a drilling fluid inlet valve is fixed on the wall protection medium pipe.

[0014] Furthermore, the main medium and the auxiliary medium are a mixture of compressed air and water, the compressed air and water are respectively located in two main medium branch pipes and two auxiliary medium branch pipes, and the wall protection medium is a biological enzyme wall protection and plugging removal drilling fluid.

[0015] Furthermore, the orifice seal includes an orifice sealer and an expansion tube connected to the orifice sealer, the orifice sealer is used to seal the borehole, the main medium pipe is connected to the orifice sealer, the expansion tube is located in the borehole, the expansion tube is connected to a drill cuttings discharge pipe, and the drill cuttings discharge pipe is connected to a drill cuttings discharge valve.

[0016] Furthermore, the drill bit is a left-hand reverse circulation drill bit.

[0017] Furthermore, the driving component includes a tunnel drill, which is in transmission connection with the double-wall drill rod. A clamp is provided outside the borehole, and the clamp is used to clamp the double-wall drill rod.

[0018] Furthermore, the central channel of the dual-channel air and water faucet is connected to the central channel of the double-wall drill pipe, the discharge end of the central channel of the dual-channel air and water faucet is connected to a connecting hose, the discharge end of the connecting hose is connected to an orifice dust removal device, the bottom end of the orifice dust removal device is provided with a solid phase discharge end, the gas phase in the orifice dust removal device is connected to the water tank through the top of the orifice dust removal device, and the water tank is connected to a sedimentation tank.

[0019] A multi-media reverse circulation drilling method for a broken soft coal seam, according to a multi-media reverse circulation drilling device for a broken soft coal seam, the operating steps include:

[0020] S1. Device installation: Drill a hole to a predetermined position, install a double-wall drill pipe on the hole sealer, install a first set of structural components on the double-wall drill pipe, start the tunnel drilling rig to advance, secure the hole sealer after advancing to the predetermined position, and install a second set of structural components on the hole sealer and double-wall drill pipe;

[0021] S2. Double-wall drill pipe drilling: Feed the main medium into the outer annulus and the auxiliary medium into the inner annulus. Start the tunnel drilling rig for drilling. After the first double-wall drill pipe is completed, retract this double-wall drill pipe, and prohibit the feeding of the main medium and the auxiliary medium.

[0022] S3. Borehole wall protection: Feed the wall protection medium into the inner annulus. Start the tunnel drilling rig for drilling. Prohibit the feeding of the wall protection medium before the first drill pipe's wall protection is completed, and then feed the auxiliary medium into the inner annulus.

[0023] S4. Adding a double-wall drill pipe: Add another double-wall drill pipe to one end of the double-wall drill pipe, and then repeat steps S2 - S3.

[0024] S5. Drill pipe withdrawal: Dismantle each structural component, disassemble the connected double-wall drill pipes, disassemble the hole mouth seal and seal the borehole.

[0025] The present invention discloses the following technical effects:

[0026] 1. Using a set of drilling tools gives full play to the respective advantages of air reverse circulation and drilling fluid wall protection. The two are effectively combined and complement each other.

[0027] 2. Collaborating with 4 forces together, the drill cuttings are continuously transported out of the hole through the central channel of the double-wall drill pipe, realizing reverse circulation drilling to form a hole.

[0028] 3. The dual-channel air swivel drilling fluid inlet. Injecting compressed air can remove the drilling fluid in the inner annulus of the double-wall drill pipe, prevent the precipitation of the drilling fluid, and there is no drilling fluid leakage when loading and unloading the drilling tools, protecting the working environment. And it supplements the energy consumption of the compressed air in the outer annulus.

[0029] 4. The hole mouth seal seals the hole mouth to form a circulating medium entering the central channel, which is conducive to forming reverse circulation. At the same time, the gas released from the coal seam in the hole also smoothly discharges out of the hole through the central channel of the double-wall drill pipe, reducing the possibility of outburst. And it cools the outer wall of the double-arm drill pipe. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required to be used in the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained based on these drawings.

[0031] Figure 1 It is a structural schematic diagram of a multi-medium reverse circulation drilling device for soft broken coal seams;

[0032] Figure 2 It is Figure 1 the partial enlarged view at A in

[0033] Among them, 1. Dual-channel air faucet; 2. Double-wall drill pipe; 3. Left-handed reverse circulation bit; 4. Outer ejector; 5. Outer eductor; 6. Hole mouth seal; 7. Tunnel drill rig; 8. Hole mouth dust removal device; 9. Pneumatic grouting pump; 10. Pneumatic agitator; 11. Chuck; 12. Sealing sleeve; 13. Pressure gauge; 14. Reaming pipe; 15. Drill slag discharge valve; 16. Main inlet air valve; 17. Main inlet water valve; 18. Clamp; 19. Power head; 20. Hydrocyclone; 21. Water tank; 22. Slag discharge valve; 23. Exhaust air return valve; 24. Water injection valve; 25. Drill cuttings liquid discharge valve; 26. Sedimentation tank; 27. Connecting rubber hose; 28. Inlet drilling fluid valve; 29. Auxiliary air valve; 30. Secondary inlet water valve. Detailed implementation mode

[0034] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative work shall fall within the protection scope of the present invention.

[0035] To make the above objects, features and advantages of the present invention more obvious and understandable, the present invention will be further described in detail below in conjunction with the accompanying drawings and specific implementation modes.

[0036] As Figure 1-2 shown, the present invention provides a multi-medium reverse circulation drilling device for broken soft coal seams, including a double-wall drill pipe 2, with a drill bit and a dual-channel air faucet 1 connected to both ends respectively, a hole mouth seal is closed at the hole mouth of the borehole, and the double-wall drill pipe 2 is rotated by a driving member; a main medium passage is provided on the hole mouth seal, the main medium passage is connected to the outer annulus of the double-wall drill pipe 2, and the main medium in the outer annulus passes through the drill bit and the first connecting member on the double-wall drill pipe 2 and is connected to the central channel of the double-wall drill pipe 2; an auxiliary medium passage is provided on the dual-channel air faucet 1, the auxiliary medium passage is connected to the inner annulus of the double-wall drill pipe 2, and the auxiliary medium in the inner annulus passes through the second connecting member on the double-wall drill pipe 2 and is connected to the outer annulus; a wall protection medium passage is provided on the auxiliary medium passage and the wall protection medium is connected to the inner annulus.

[0037] It can be understood that during normal drilling, there are 2 air inlet channels for the compressed air, making the reverse circulation complete. One way is that the main medium is injected into the annulus between the double-wall drill pipe 2 and the hole wall, that is, the outer annulus, through the hole mouth seal. The other way is that the auxiliary medium enters the annular gap between the inner and outer pipes of the double-wall drill pipe 2, that is, the inner annulus, through the dual-channel air faucet 1.

[0038] It can be understood that a first connecting member and a second connecting member are provided on the double-wall drill pipe 2. The outer annulus is connected to the central channel of the double-wall drill pipe 2 through the first connecting member, and the inner annulus of the double-wall drill pipe 2 is connected to the outer annulus through the second connecting member.

[0039] It can be understood that the wall protection medium passage is used to inject the wall protection medium into the borehole, that is, to perform grouting for wall protection. The auxiliary medium and the wall protection medium are used separately. That is, when using the auxiliary medium, the wall protection medium is not used.

[0040] In a further optimized solution, the main medium passage includes a main medium pipe connected to the inside of the hole mouth seal. The medium inlet ends of the main medium pipe are respectively connected to two main medium branch pipes. A main inlet air valve 16 and a main inlet water valve 17 are respectively fixed on the two main medium branch pipes. The first connecting member is an external ejector 5 fixed on the side wall of the double-wall drill pipe 2, and the second connecting member is an external injector 4 fixed on the side wall of the double-wall drill pipe 2.

[0041] It can be understood that during normal drilling, its usage method is as follows: during drilling, the main path compressed air passes through the hole mouth seal and enters the outer annulus. The compressed air flow is divided into two strands by the external ejector 5. One strand enters the central channel of the double-wall drill pipe 2 along the injection holes of the external ejector 5. The multiple injection holes rotate continuously with the drill pipe, forming a rotating eddy current towards the outside of the borehole. From the bottom of the hole to the air flow convergence part of the injection holes, the central channel of the double-wall drill pipe 2 is always a negative pressure area. Under the negative pressure of the central channel of the double-wall drill pipe 2, a very strong suction force is generated on the surrounding fluid.

[0042] The other strand of compressed air flow passes through the drill bit and shoots towards the bottom of the hole. The drill bit is a left-handed reverse circulation drill bit 3. The left-handed spiral guide groove of the left-handed reverse circulation drill bit 3 forms a force for pushing the drill cuttings towards the central channel at the bottom of the hole during drilling. Since the lip surface of the left-handed reverse circulation drill bit 3 is stepped, it is beneficial to form a refraction force and a reflection force of the compressed air at the bottom of the hole, ensuring the reverse circulation effect.

[0043] Specifically, the two main medium branch pipes are respectively connected to a compressed air station (not shown in the figure) and a water supply station (not shown in the figure). The main inlet air valve 16 and the main inlet water valve 17 are respectively used to control the air inlet and the water inlet.

[0044] In a further optimized solution, the auxiliary medium passage includes an auxiliary medium pipe connected to the double-channel air swivel 1. The medium inlet ends of the auxiliary medium pipe are respectively connected to two auxiliary medium branch pipes. An auxiliary air valve 29 and a secondary water valve 30 are respectively fixed on the two auxiliary medium branch pipes.

[0045] It can be understood that the auxiliary medium, that is, the auxiliary compressed air, enters the gap between the inner pipe and the outer pipe of the double-wall drill pipe 2, that is, the inner annulus, through the double-channel air swivel 1, and is ejected into the outer annulus through the external injector 4, and converges with the main path compressed air to strengthen the removal of drill cuttings on the hole wall and form a refraction force and a reflection force at the bottom of the hole.

[0046] Among them, the two auxiliary medium branch pipes are correspondingly connected to an air supply station and a water supply station, and the auxiliary air pressure valve 29 and the secondary water inlet valve 30 are used to control the water inlet and air inlet.

[0047] In a further optimized solution, the wall protection medium passage includes a wall protection medium pipe connected to the auxiliary medium pipe. There are two pneumatic mixers 10 arranged outside the drill hole. The discharge ends of the two pneumatic mixers 10 are connected to the wall protection medium pipe through a pneumatic grouting pump 9. An inlet drilling fluid valve 28 is fixed on the wall protection medium pipe.

[0048] During drilling, intermittent wall protection is carried out. That is, after each double-wall drill pipe 2 is completed, one is retracted, and then the main inlet air pressure valve 16, the main water inlet valve 17, the auxiliary air pressure valve 29, and the secondary water inlet valve 30 are closed. The drilling fluid raw materials are stirred by the pneumatic mixer 10. The pneumatic grouting pump 9 is started and the inlet drilling fluid valve 28 is opened. Through the double-channel air swivel 1, high-pressure bio-enzyme wall protection and plugging removal drilling fluid is transported to the drill hole. The driving part is started to drill and carry out wall protection. The drilling fluid passes through the inner annulus between the inner and outer pipes of the double-wall drill pipe 2 and is transported to the outer ejector 4, and is ejected through the ejection holes for wall protection and lubricating the drill tool, without participating in the reverse circulation.

[0049] Among them, for the two pneumatic mixers 10, one is used to stir the wall protection drilling fluid and the other is used to stir the plugging removal fluid. The outlets of the two pneumatic mixers 10 are connected by a three-way pipe and communicated with the suction port of the pneumatic grouting pump 9 and injected into the hole at the same time. Raw materials are added according to the ratio provided by the technician to stir the wall protection drilling fluid or the plugging removal fluid.

[0050] In a further optimized solution, the main medium and the auxiliary medium are a mixture of compressed air and water. The compressed air and water are respectively located in the two main medium branch pipes and the two auxiliary medium branch pipes. The wall protection medium is bio-enzyme wall protection and plugging removal drilling fluid. The compressed air is mixed with a small amount of water, which can be used for dust removal, temperature reduction and efficient slag discharge, and eliminates the safety hazards of high temperature of the drill tool and dust hazards. The drilling effect is better. The bio-enzyme wall protection and plugging removal drilling fluid is ejected through the outer ejector 4 for wall protection and lubricating the tool, and does not participate in the circulation, preventing the collapse of the hole wall, maintaining the stability of the hole wall, reducing the wear of the drill bit and the double-wall drill pipe 2, and is suitable for deep hole drilling.

[0051] In a further optimized solution, the hole mouth seal includes a hole mouth seal 6 and an underreaming pipe 14 connected to the hole mouth seal 6. The hole mouth seal 6 is used to block the drill hole. The main medium pipe is connected to the hole mouth seal 6. The underreaming pipe 14 is located in the drill hole. A drill slag discharge pipe is connected to the underreaming pipe 14, and a drill slag discharge valve 15 is connected to the drill slag discharge pipe.

[0052] The debris removal valve 15 is used for the initial installation of the reaming tube 14 and the orifice sealer 6. Initially, the driver is activated to advance the reaming tube 14 of the orifice sealer 6 into the coal body, and the reaming tube 14 of the orifice sealer 6 enters the coal body along with the drill bit. When the reaming tube 14 has penetrated the coal to a depth of 0.7 or 1.4 meters, drilling is stopped, the clamping head 11 is loosened, and the screws are tightened, allowing the slips to detach from the drill pipe. The orifice sealer 6 is secured, and the debris removal valve 15 is closed. The main inlet pressure air valve 16 and the main inlet water valve 17 are connected to the orifice sealer 6.

[0053] Specifically, a sealing sleeve 12 is provided on the hole sealer 6 , the double-wall drill pipe 2 is passed through the hole sealer 6 and the sealing sleeve 12 , and the sealing of the connection is achieved by the sealing sleeve 12 .

[0054] Furthermore, a pressure gauge is fixed on the reaming pipe 14, and the pressure gauge 13 is arranged to monitor the changes in the borehole injection pressure.

[0055] A further optimization solution is to use a left-hand reverse circulation drill bit 3. The lip surface of the left-hand reverse circulation drill bit 3 features a left-hand spiral guide groove that rotates in the opposite direction of the drive element during normal drilling. This creates a force that pushes the drill toward the bottom of the hole. Under high-speed rotation, compressed air, carrying drill cuttings, is forced toward the central channel of the left-hand reverse circulation drill bit 3. The negative pressure in the central channel of the left-hand reverse circulation drill bit 3 creates an entrainment effect on the surrounding fluid, allowing gas carrying drill cuttings from the bottom of the hole to easily enter the central channel of the left-hand reverse circulation drill bit 3. The cuttings are then efficiently returned to the outside of the hole along the central channel of the double-walled drill pipe 2, creating a continuous reverse circulation system. The compressed air cools the drill tool, carries the cuttings, and cleans the drill hole.

[0056] According to a further optimized solution, the driving part includes a tunnel drill rig 7, which is connected to the double-wall drill rod 2 by transmission. A clamp 18 is provided outside the borehole, and the clamp 18 is used to clamp the double-wall drill rod 2.

[0057] Specifically, the tunnel drilling rig 7 is equipped with a power head 19, which is used to connect with the double-wall drill pipe 2 and transmit power to it. The tunnel drilling rig 7 can adopt existing technology.

[0058] The clamp 18 is used to clamp and support the double-wall drill pipe 2 , that is, when the power head 19 is separated from the double-wall drill pipe 2 , the double-wall drill pipe 2 can be fixed by the clamp 18 .

[0059] To further optimize the solution, the central channel of the dual-channel gas and water faucet 1 is connected to the central channel of the double-wall drill pipe 2, and the discharge end of the central channel of the dual-channel gas and water faucet 1 is connected to a connecting hose 27, and the discharge end of the connecting hose 27 is connected to an orifice dust removal device 8, and a solid phase discharge end is provided at the bottom end of the orifice dust removal device 8. The gas phase in the orifice dust removal device 8 is connected to the water tank 21 through the top of the orifice dust removal device 8, and the water tank 21 is connected to a sedimentation tank 26.

[0060] Specifically, the compressed air carries the drill cuttings and continuously returns upward through the central channel of the double-wall drill pipe 2. The returned drill cuttings pass through the through-hole of the double-channel air swivel 1, and then through the connecting rubber hose 27, and enter the cyclone 20 of the hole mouth dust removal device 8 for the first primary separation of the heavy phase and the light phase. The light phase (gas phase and solid phase) returned from the cyclone 20 enters the water tank 21. After water bath, the second separation of the solid phase and the gas phase occurs. After separation, the gas phase (return air and gas) is discharged into the lower airway roadway through monitoring. When the gas discharged from the hole increases and exceeds the standard, it is necessary to timely connect it to the pipeline of the gas drainage system so that the gas released from the borehole can be timely drained away and does not enter the roadway air current. The liquid-phase drill cuttings in the water tank 21 are connected to the sedimentation tank 26. After precipitation, they are stacked neatly with the solid phase discharged from the hole mouth dust removal device 8 and are uniformly loaded onto the transport conveyor and transported to the ground.

[0061] Furthermore, a drill cutting liquid discharge valve 25 is connected to the bottom end of the water tank 21, a water injection valve 24 and a return air discharge valve 23 are connected to the top of the water tank 21, and a slag discharge valve 22 is connected to the bottom end of the cyclone 20.

[0062] A multi-medium reverse circulation drilling method for broken soft coal seams, according to the multi-medium reverse circulation drilling device for broken soft coal seams, the operation steps include,

[0063] S1. Device installation: Drill a hole at the predetermined position, install the double-wall drill pipe 2 on the hole mouth seal 6, install the first set of structural components on the double-wall drill pipe 2, start the tunnel drilling rig 7 to advance, fix the hole mouth seal 6 after advancing to the predetermined position, and install the second set of structural components on the hole mouth seal 6 and the double-wall drill pipe 2.

[0064] Layout the construction site, move the tunnel drilling rig 7, use a geological compass to determine the azimuth and inclination angle, and stabilize the drill.

[0065] Hole enlargement: First, use a φ73mm flush drill pipe and a φ133mm non-core bit, and carry out low-speed open-hole drilling in the positive circulation of compressed air to a depth of 0.7m or 1.4m. Remove the positive circulation drilling tools. Install the hole mouth seal 6. Replace with reverse circulation drilling tools.

[0066] Install the hole mouth seal 6. Insert a 1.5-meter-long double-wall drill pipe 2 from behind the power head 19 and pass it through the gripper 18. The front end is inserted into the sealing sleeve 12 of the hole mouth seal 6, passes through the hole enlargement pipe 14, clamp the gripper 18, screw the external ejector 5, the external injector 4, and the left-handed reverse circulation bit 3 onto the double-wall drill pipe 2 in sequence, tighten the tightening wire on the chuck 11, and the slip chuck will hold the double-wall drill pipe 2. Make the tail of the double-wall drill pipe 2 protrude from behind the power head 19, start the tunnel drilling rig 7 and advance towards the coal body, and the hole enlargement pipe 14 of the hole mouth seal 6 will enter the coal body along with the bit. When the hole enlargement pipe 14 enters the coal by 0.7 or 1.4m deep, then stop drilling, loosen the tightening wire on the chuck 11, and the slip chuck will disengage from the double-wall drill pipe 2. Fix the hole mouth seal 6 and close the drill slag discharge valve 15. Connect the main inlet compressed air valve 16, the main inlet water valve 17, and the pressure gauge 13 to the hole mouth seal 6.

[0067] Install a dual-channel air faucet 1, which is connected to the double-wall drill pipe 2 after the power head 19. Its quick connectors are connected to the drilling fluid inlet valve 28, the auxiliary compressed air valve 29, and the secondary water inlet valve 30. The drilling fluid inlet valve 28 is connected to the drilling fluid injection pipe of the pneumatic grouting pump 9, the auxiliary compressed air valve 29 is connected to the compressed air supply pipeline, and the secondary water inlet valve 30 is connected to the water supply pipeline. The quick connector at its rear head is connected to the hole dust removal device 8.

[0068] S2. Drilling of the double-wall drill pipe 2: Inject the main medium into the outer annulus and the auxiliary medium into the inner annulus, start the tunnel drill 7 to drill. After the first double-wall drill pipe 2 is completed, retract this double-wall drill pipe 2, and prohibit the injection of the main medium and the auxiliary medium.

[0069] Open the main compressed air inlet valve 16 and the main water inlet valve 17 on the hole seal 6. At the same time, open the auxiliary compressed air valve 29 and the secondary water inlet valve 30 on the dual-channel air faucet 1 to simultaneously transport compressed air into the hole. Operate the tunnel drill 7 to make the chuck of the power head 19 clamp, the gripper 18 release, and start drilling. After the first drill pipe is completed, retract one drill pipe, and then close all compressed air channels.

[0070] S3. Borehole wall protection: Inject the wall protection medium into the inner annulus, start the tunnel drill 7 to drill. Before the first drill pipe's wall protection is completed, prohibit the injection of the wall protection medium, and then inject the auxiliary medium into the inner annulus.

[0071] Use two pneumatic mixers 10 to provide the wall protection medium. Open the liquid outlet valve of the pneumatic mixer 10, start the pneumatic grouting pump 9, open the drilling fluid inlet valve 28, and transport the mixture of wall protection drilling fluid and plugging removal fluid into the borehole. Start the tunnel drill 7 for wall protection. Note to inject the wall protection drilling fluid volume and the plugging removal fluid volume according to the calculated amount, and adjust according to the actual situation on site. Before the wall protection of the first drill pipe is completed, close the pneumatic grouting pump 9. At the same time, open the auxiliary compressed air valve 29 on the dual-channel air faucet 1 to inject compressed air to remove the drilling fluid in the inner annulus. After the removal is completed, close the auxiliary compressed air valve 29.

[0072] S4. Connecting the double-wall drill pipe 2: Connect another double-wall drill pipe 2 to one end of the double-wall drill pipe 2, and then repeat steps S2 - S3.

[0073] Connect the second double-wall drill pipe 2 to the first double-wall drill pipe 2. Open the main compressed air inlet valve 16 and the main water inlet valve 17 on the hole seal 6. At the same time, open the auxiliary compressed air valve 29 and the secondary water inlet valve 30 on the dual-channel air faucet 1 to simultaneously transport compressed air into the hole. When compressed air returns from the hole, continue drilling. After the second drill pipe is completed, retract one drill pipe, close all compressed air valves, open the pneumatic grouting pump 9, transport the wall protection drilling fluid and the plugging removal fluid into the borehole, and start the tunnel drill 7 for wall protection. Repeat this process to drill the double-wall drill pipe 2 into the hole one by one. When reaching the designed hole depth (final hole), blow the hole.

[0074] S5. Drill withdrawal: Disassemble each structural component, disassemble the connected double-wall drill pipe 2, disassemble the hole mouth seal 6 and seal the borehole.

[0075] Disassemble the main medium pipe on the hole mouth seal 6, disassemble the dual-channel air swivel 1 and its auxiliary medium pipe, drilling fluid injection pipe, and slag discharge pipe. When pulling out the double-wall drill pipe 2 from the hole, pull out one and disassemble one. When disassembling the last double-wall drill pipe 2, tighten the clamp 11 on the hole mouth seal 6 and rotate to pull out the hole mouth seal 6. Disassemble the reaming pipe 14, left-handed reverse circulation bit 3, and double-wall drill pipe 2.

[0076] Seal the borehole. After the drill withdrawal is completed, insert the drainage perforated pipe and solid pipe, seal the borehole, connect to the working face gas drainage system, and clean the coal slime on-site.

[0077] Clean the drill site. The drill cuttings from drilling should be neatly stacked against the wall and dried. After drying, they should be promptly transported away through the coal transportation system to avoid affecting on-site operations. For the coal transportation system, the drill cuttings during the borehole construction process are transported onto the main transportation system by the belt at the operation site and reach the ground.

[0078] In the description of the present invention, it should be understood that the orientation or positional relationship indicated by the terms "longitudinal", "transverse", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc. is based on the orientation or positional relationship shown in the drawings, and is only for the convenience of describing the present invention, rather than indicating or implying that the device or component referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be construed as a limitation to the present invention.

[0079] The embodiments described above are only for describing the preferred embodiments of the present invention, and do not limit the scope of the present invention. Without departing from the design spirit of the present invention, various deformations and improvements made by those of ordinary skill in the art to the technical solutions of the present invention should fall within the protection scope determined by the claims of the present invention.

Claims

1. A multi-media reverse circulation drilling device for crushed soft coal seams, characterized in that: include, A double-wall drill rod (2) is connected to a drill bit and a dual-channel gas and water tap (1) at both ends, the orifice of the drill hole is sealed with an orifice seal, and the double-wall drill rod (2) is rotated by a driving member; A main medium passage is provided on the orifice seal, the main medium passage is connected to the outer annulus of the double-wall drill pipe (2), and the main medium in the outer annulus is connected to the central channel of the double-wall drill pipe (2) through the drill bit and the first connecting piece on the double-wall drill pipe (2); An auxiliary medium passage is provided on the dual-channel gas and water tap (1), the auxiliary medium passage is connected to the inner annulus of the double-wall drill pipe (2), and the auxiliary medium in the inner annulus is connected to the outer annulus via a second connecting piece on the double-wall drill pipe (2); a wall protection medium passage, which is arranged on the auxiliary medium passage and the wall protection medium is in communication with the inner annulus; The main medium passage comprises a main medium pipe connected to the orifice seal, the medium inlet end of the main medium pipe is connected to two main medium branch pipes, and the two main medium branch pipes are respectively fixed with a main pressure air valve (16) and a main water inlet valve (17), the first connecting member is an external ejector (5) fixed to the side wall of the double-wall drill pipe (2), and the second connecting member is an external ejector (4) fixed to the side wall of the double-wall drill pipe (2); The auxiliary medium passage comprises an auxiliary medium pipe connected to the dual-channel air and water tap (1), the medium inlet end of the auxiliary medium pipe being connected to two auxiliary medium branch pipes, and an auxiliary air pressure valve (29) and a secondary water inlet valve (30) being fixed to the two auxiliary medium branch pipes respectively; The main medium and the auxiliary medium are a mixture of compressed air and water. The compressed air and water are respectively located in two main medium branch pipes and two auxiliary medium branch pipes. The wall protection medium is a biological enzyme wall protection and plugging removal drilling fluid.

2. The multi-media reverse circulation drilling device for crushed soft coal seams according to claim 1, characterized in that: The wall protection medium passage includes a wall protection medium pipe connected to the auxiliary medium pipe. Two pneumatic mixers (10) are arranged outside the borehole. The discharge ends of the two pneumatic mixers (10) are connected to the wall protection medium pipe through a pneumatic grouting pump (9). A drilling fluid inlet valve (28) is fixed on the wall protection medium pipe.

3. The multi-media reverse circulation drilling device for crushed soft coal seams according to claim 1 is characterized in that: The orifice seal comprises an orifice sealer (6) and a reaming tube (14) connected to the orifice sealer (6); the orifice sealer (6) is used to seal the borehole; the main medium pipe is connected to the orifice sealer (6); the reaming tube (14) is located in the borehole; the reaming tube (14) is connected to a drilling debris discharge pipe; and the drilling debris discharge pipe is connected to a drilling debris discharge valve (15).

4. The multi-media reverse circulation drilling device for crushed soft coal seams according to claim 1, characterized in that: The drill bit is a left-hand reverse circulation drill bit (3).

5. The multi-media reverse circulation drilling device for crushed soft coal seams according to claim 1, characterized in that: The driving component includes a tunnel drill (7), the tunnel drill (7) is in transmission connection with the double-wall drill rod (2), and a clamp (18) is provided outside the drill hole, and the clamp (18) is used to clamp the double-wall drill rod (2).

6. The multi-media reverse circulation drilling device for crushed soft coal seams according to claim 1, characterized in that: The central channel of the dual-channel gas-water tap (1) is connected to the central channel of the double-wall drill pipe (2); the discharge end of the central channel of the dual-channel gas-water tap (1) is connected to a connecting hose (27); the discharge end of the connecting hose (27) is connected to an orifice dust removal device (8); a solid phase discharge end is provided at the bottom end of the orifice dust removal device (8); the gas phase in the orifice dust removal device (8) is connected to a water tank (20) via the top end of the orifice dust removal device (8); and the water tank (20) is connected to a sedimentation tank (26).

7. A multi-media reverse circulation drilling method for a crushed soft coal seam, comprising a multi-media reverse circulation drilling device for a crushed soft coal seam according to any one of claims 1 to 6, characterized in that: The steps include: S1. Installation of the device: drilling a hole at a predetermined position, installing a double-wall drill pipe (2) on the hole sealer (6), installing a first set of structural components on the double-wall drill pipe (2), starting the tunnel drilling rig (7) to advance, fixing the hole sealer (6) after advancing to the predetermined position, and installing a second set of structural components on the hole sealer (6) and the double-wall drill pipe (2); S2, double-wall drill rod (2) drilling: the main medium is introduced into the outer annulus, the auxiliary medium is introduced into the inner annulus, the tunnel drilling rig (7) is started for drilling, and after the first double-wall drill rod (2) is drilled, the double-wall drill rod (2) is withdrawn, and the introduction of the main medium and the auxiliary medium is prohibited; S3, drilling wall protection: inject wall protection medium into the inner annulus, start the tunnel drilling rig (7) to drill, and do not inject wall protection medium before the first drill rod is completed, then inject auxiliary medium into the inner annulus; S4, adding a double-wall drill rod (2): adding another double-wall drill rod (2) to one end of the double-wall drill rod (2), and then repeating steps S2-S3; S5. Drill withdrawal: dismantle the structural components, dismantle the connected double-wall drill pipe (2), dismantle the hole sealer (6) and seal the borehole.

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