Radial multi-branch hole hydraulic jet rapid hole-forming device for coal seam gas extraction

Abstract

The present application belongs to the technical field of coal mine gas extraction, and relates to a coal seam gas extraction radial multi-branch hole hydraulic jet rapid hole forming device, which comprises a radial drilling device and a sandwich drill pipe. The sandwich drill pipe comprises an inner drill pipe and an outer drill pipe sleeved on the inner drill pipe, and a drill tool is installed at one end of the sandwich drill pipe. The drill tool is in communication with an outer channel between the inner drill pipe and the outer drill pipe, and a safety valve is arranged in the drill tool or the outer channel close to the drill tool, so that the water pressure in the outer channel is not communicated with the drill tool when the water pressure is lower than a certain value. The present application exhibits significant beneficial effects in improving construction efficiency, enhancing construction accuracy and safety, simplifying process flow, reducing cost and improving environmental protection, etc. These effects collectively provide strong support for the safe production of coal mines and the efficient use of gas, and have wide application prospects and practical value.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of coal mine gas extraction, and relates to a radial multi-branch hole hydraulic jet rapid hole-forming device for coal seam gas extraction. BACKGROUND

[0002] Significant improvement of the permeability of complex coal seams is the key to gas disaster prevention and coal seam gas extraction. Existing coal seam permeability improvement devices mainly change the physical structure of the coal seam to increase the permeability of the coal seam, thereby improving the gas extraction efficiency. The devices mainly include dense drilling construction, pre-splitting blasting, hydraulic punching, hydraulic slotting and hydraulic fracturing. Dense drilling construction increases the surface area of the coal seam by drilling a large number of small-diameter drill holes in the coal seam to improve the gas extraction efficiency. The pre-splitting blasting device increases the permeability of the coal seam by the shock wave generated by the explosion. The hydraulic punching and hydraulic slotting devices cut the coal seam by high-pressure water jets to increase the permeability of the coal seam. The hydraulic fracturing device forms cracks in the coal seam by high-pressure water jets to increase the permeability of the coal seam. However, the application effect of these coal seam permeability improvement devices is not ideal, and they are easily limited by economy, safety and timeliness.

[0003] In recent years, a leading technology for improving the permeability of coal seams, i.e., a high-pressure hydraulic jet radial drilling device, which is economic, efficient, green and safe, has gradually become a research hotspot. The high-pressure hydraulic jet radial drilling device can achieve 0-90° steering drilling in a conventional main hole to form a group of branch drill holes with a diameter of 30-60 mm. The drilling efficiency is high, the cost is low, and the coal seam drilling can reach 3-5 m / min. The drilling process uses clean water drilling, which is green, environmentally friendly and safe and reliable. At present, the high-pressure hydraulic jet radial drilling coal seam permeability improvement device is usually used for the hydraulic jet tree-shaped drilling coal seam permeability improvement method. The device uses a through-hole drilling as a mother hole, and the jet drill bit and hose in the device reach the coal seam under the push of high-pressure water jets, and then drill into branch holes one by one through the steering device to form a multi-layer radial group of drill holes, thereby achieving coal seam permeability improvement. For example, a coal mine underground coal seam tree-shaped drilling composite fracturing uniform permeability improvement equipment is disclosed in Chinese Patent No. CN105525900B. The complete equipment can be divided into a hole-forming system and a fracturing system. The hole-forming system includes a drilling machine, a drill rod, a drill bit, a support, a water tank, a high-pressure pump, a winch, a propulsion mechanism, a chuck, a high-pressure hose and a self-advancing drill bit. The fracturing system includes a water tank, a high-pressure pump, a pressure gauge, a high-pressure rubber pipe and a hole sealing device.

[0004] However, the use process of the existing high-pressure hydraulic jet radial drilling coal seam permeability improvement device is complex. The device needs to be retreated and the steering device needs to be adjusted multiple times during the construction process, and only one radial hole can be constructed at a time, which leads to low construction efficiency and high construction difficulty, and the device is difficult to be widely applied. SUMMARY

[0005] Therefore, the coal seam gas extraction radial multi-branch hole hydraulic jet rapid hole forming device is provided to solve the problems in the background art.

[0006] To achieve the above-mentioned purpose, the present application provides the following technical solutions:

[0007] A coal seam gas extraction radial multi-branch hole hydraulic jet rapid hole forming device, comprising a radial drilling device and a sandwich drill pipe, the sandwich drill pipe comprises an inner drill pipe and an outer drill pipe sleeved on the inner drill pipe, and a drill tool is installed at one end of the sandwich drill pipe, and the drill tool is in communication with an outer channel between the inner drill pipe and the outer drill pipe, and a safety valve is arranged in the drill tool or the outer channel close to the drill tool, so that the water pressure in the outer channel is not communicated with the drill tool when it is lower than a certain value;

[0008] The radial drilling device comprises a self-feeding drill bit, a connecting hose, a thrust water wheel, a jet controller, a flow distribution spring, a flow sealing piston and a return one-way waterway valve, the jet controller is slidingly arranged in the outer drill pipe and slidingly sleeved on the inner drill pipe, and slides in the axial direction of the sandwich drill pipe under the push of water flow;

[0009] The flow sealing piston is arranged in the outer drill pipe and sleeved on the inner drill pipe, and the end of the flow sealing piston close to the drill tool is fixedly connected with the outer drill pipe;

[0010] The end of the jet controller close to the drill tool is sleeved on the flow sealing piston and is in transition connection, and a flow distribution spring arranged in the axial direction of the drill rod is arranged between the end close to the jet controller and the flow sealing piston to provide a reset elastic force of the jet controller away from the drill tool;

[0011] The end of the flow sealing piston away from the drill tool is fixedly connected with the inner drill pipe to form a sealed connection, and the inner cavity of the flow sealing piston and the end close to the drill tool are gap-connected with the inner drill pipe to form a first waterway, and an overflow hole is arranged on the flow sealing piston, and an overflow ring groove corresponding to the overflow hole is arranged on the jet controller, so that when the overflow hole and the overflow ring groove correspond, the first waterway is communicated with the inner cavity of the jet controller through the overflow hole and the overflow ring groove;

[0012] The thrust water wheel is slidingly arranged between the jet controller and the inner drill pipe and slides in the axial direction of the drill rod under the push of water flow, and has a water passage on it to communicate the waterways on both sides of the thrust water wheel, one end of the connecting hose is fixedly connected with the thrust water wheel, and the connecting hose is connected with the self-feeding drill bit arranged outside the outer drill pipe and in the radial direction through the communication of the thrust water wheel with the waterway on the side of the thrust water wheel away from the drill tool, and the other end of the connecting hose penetrates the jet controller and the outer drill pipe to connect the self-feeding drill bit, so as to provide high-pressure water to the self-feeding drill bit to make the self-feeding drill bit drill in the radial direction of the main hole, thereby forming a radial branch hole;

[0013] The return unidirectional waterway valve is installed on the inner drill pipe to connect the inner channel and the outer channel in the inner drill pipe, and the return unidirectional waterway valve is arranged at the end of the flow sealing piston close to the drill tool to make the water flow in the inner drill pipe flow unidirectionally into the outer channel and flow through the first waterway to the end away from the drill tool, so as to drive the thrust water wheel to slide to the end away from the drill tool, to recover the connecting hose and the self-advancing drill bit in the radial branch hole.

[0014] Further, a guide protrusion is arranged on the outer side of the outer drill pipe to control the drilling direction of the self-advancing drill bit.

[0015] Further, a strip-shaped hole is arranged in the guide protrusion to accommodate a guide cantilever and a rocker arm, one end of the guide cantilever is hinged to the guide protrusion, the other end of the guide cantilever is provided with a U-shaped groove, and the other end of the guide cantilever is hinged to one end of the rocker arm through the U-shaped groove, the other end of the rocker arm is movably connected to the outer edge of the water jet controller, so that the rocker arm slides with the water jet controller, and in turn drives the guide cantilever to protrude outward when the water jet controller slides to the side close to the drill tool.

[0016] A first through hole for accommodating the connecting hose is arranged in the guide cantilever, so that the connecting hose is connected to the self-advancing drill bit through the first through hole, and in turn the self-advancing drill bit is guided by the guide cantilever to control the drilling direction of the self-advancing drill bit.

[0017] Further, the water jet controller has a second through hole for the connecting hose, and a first sealing ring is arranged on the connecting hose at the second through hole to prevent water flow in the inner cavity of the water jet controller from leaking from the second through hole.

[0018] Further, second sealing rings are arranged at both ends of the outer side of the water jet controller to form a sliding seal between the water jet controller and the outer drill pipe.

[0019] Further, it further comprises a high-pressure water cart, a high-pressure water pipeline, a flow channel switching valve, and a drilling machine, the drilling machine is used to clamp the sandwich drill pipe to drill the main hole and drive the sandwich drill pipe to advance or retreat to a specified position.

[0020] The high-pressure water cart is connected to the flow channel switching valve through the high-pressure water pipeline, and the flow channel switching valve is connected to the end of the sandwich drill pipe to input high-pressure water into the inner channel or the outer channel of the sandwich drill pipe and receive the backflow water in the outer channel.

[0021] Further, the flow channel switching valve has two water outlets matched with the sandwich drill pipe to respectively connect the inner channel and the outer channel of the sandwich drill pipe, and a three-way valve is further arranged on the water outlet connected to the outer channel to discharge the backflow water in the outer channel through the three-way valve.

[0022] Further, the high-pressure water cart comprises a high-pressure water pump, a high-pressure water tank and a pressure regulating device, the water inlet of the high-pressure water pump is connected to the high-pressure water tank, and the high-pressure water outlet is connected to the pressure regulating device and the high-pressure water pipeline in sequence.

[0023] Further, the high-pressure water cart further comprises a remote pressure regulating device, which is connected to the pressure regulating device through a pressure regulating pipeline, so that the remote pressure regulating device controls the pressure regulating device through the pressure regulating pipeline, thereby realizing remote control of the pressure regulating device.

[0024] Further, the connecting hose is at least one and is uniformly arranged on the thrust water wheel in the circumferential direction, and the self-feeding drill bit corresponds to the connecting hose one by one.

[0025] The beneficial effects of the present application are:

[0026] The purpose of the present application is to provide a coal seam gas extraction radial multi-branch hole hydraulic jet rapid hole forming device, compared with the traditional coal seam permeability improvement device and method, its beneficial effects mainly reflect in the following aspects:

[0027] Improve construction efficiency: through the special design of the interlayer drill pipe and the radial drilling tool, the technical scheme can quickly construct multiple radial branch holes in a single main drill hole, which greatly improves the construction efficiency of the drill hole. The traditional permeability improvement method often needs to construct each radial branch hole respectively, while the technical scheme can realize one-time construction of multiple radial branch holes, thereby significantly reducing the construction time and cost.

[0028] Enhance construction accuracy and safety: by accurately adjusting the flow rate and pressure of the high-pressure water pump truck, the technical scheme can realize accurate control of the radial branch hole construction process, which not only makes the construction process safer, but also ensures the accuracy and consistency of the radial branch hole, further improving the effect of coal seam permeability improvement.

[0029] Simplify the process flow: compared with the complex hydraulic jet tree-shaped drill hole method, the process flow of the technical scheme is simpler and more convenient to operate, without the need for multiple reaming and reaming, and the main hole and radial branch hole are constructed with the same drill rod, which not only reduces the construction difficulty, but also reduces the uncertainty in the operation process, improves the stability and reliability of the whole work.

[0030] Reduce cost and environmental protection: due to the improvement of construction efficiency and the simplification of process flow, the technical scheme can significantly reduce the cost of coal mine gas extraction. At the same time, as an environmentally friendly construction method, hydraulic jet technology reduces environmental pollution and meets the current concept of green development.

[0031] In summary, this technical solution demonstrates significant benefits in improving construction efficiency, enhancing construction accuracy and safety, simplifying processes, reducing costs and improving environmental friendliness, and increasing coal seam permeability. These effects collectively provide strong support for safe coal mine production and efficient gas utilization, exhibiting broad application prospects and practical value.

[0032] Other advantages, objectives, and features of the invention will be set forth in part in the description which follows, and in part will be apparent to those skilled in the art from the following examination, or may be learned from practice of the invention. The objectives and other advantages of the invention can be realized and obtained through the following description. Attached Figure Description

[0033] To make the objectives, technical solutions, and advantages of the present invention clearer, the preferred embodiments of the present invention will be described in detail below with reference to the accompanying drawings, wherein:

[0034] Figure 1 This is a cross-sectional schematic diagram of a radial multi-branch hydraulic jet rapid drilling device for coal seam gas extraction (in the state of self-advancing drill bit recovery).

[0035] Figure 2 This is a three-dimensional structural diagram (drilling state) of a radial multi-branch hole hydraulic jet rapid hole-forming device for coal seam gas extraction;

[0036] Figure 3 This is a schematic diagram of the jet controller.

[0037] Figure 4 This is a schematic diagram of the sealing piston structure;

[0038] Figure 5 This is a schematic diagram of the structure of a sandwich drill pipe;

[0039] Figure 6 This is a schematic diagram of a rapid drilling device for radial multi-branch hole hydraulic jetting in coal seam gas extraction (including a high-pressure water jet and a drilling rig).

[0040] : high pressure water pump 101, high pressure water outlet 102, pressure regulating device 103, pressure regulating pipeline 104, remote pressure regulating device 105, high pressure water tank 106, high pressure water pipeline 2, flow channel switching valve 3, sandwich drill pipe 4, inner drill pipe 401, outer drill pipe 402, annular fixed water passing plate 403, connecting thread 404, main hole 5, coal seam 6, coal seam roof 601, coal seam floor 602, drilling tool 7, radial branch hole 8, radial drilling device 9, self-advancing drill bit 901, connecting hose 902, guide protrusion 903, guide cantilever 904, first through hole 9041, rocker arm 905, thrust water wheel 906, jet controller 907, second through hole 9071, flow passing ring groove 9072, flow distribution spring 908, flow blocking piston 909, flow passing hole 9091, first sealing ring 9010, second sealing ring 9011, return one-way waterway valve 9012, drilling machine 10. DETAILED DESCRIPTION

[0041] The advantages and effects of the present application can be easily understood by those skilled in the art from the description. The present application can also 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 noted that the drawings provided in the following embodiments only schematically illustrate the basic concept of the present application, and the following embodiments and features in the embodiments can be combined with each other without conflict.

[0042] The drawings are only used for exemplary illustration, and the representation is only a schematic diagram, not a physical diagram, and cannot be understood as a limitation of the present application. In order to better illustrate the embodiments of the present application, some components in the drawings can be omitted, enlarged or reduced, and do not represent the actual product size. It can be understood by those skilled in the art that some known structures and their descriptions in the drawings can be omitted.

[0043] The same or similar reference numerals in the drawings of the embodiments of the present application correspond to the same or similar components; in the description of the present application, it should be understood that if the terms "upper", "lower", "left", "right", "front", "back" and the like indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings, only for the convenience of describing the present application and simplifying the description, and do not indicate or imply that the devices or elements referred to must have a particular orientation, be constructed and operated in a particular orientation, therefore the terms describing the positional relationship in the drawings are only used for exemplary illustration, and cannot be understood as a limitation of the present application, for those skilled in the art, the specific meaning of the above terms can be understood according to the specific circumstances.

[0044] Please refer to Figures 1-6The utility model provides a kind of coal seam gas extraction radial multi-branch hole hydraulic jet rapid hole-forming device, including radial drilling device 9 and sandwich drill pipe 4, the sandwich drill pipe 4 includes inner drill pipe 401, outer drill pipe 402 being set on inner drill pipe 401 and annular fixed water passage plate 403 being arranged between inner drill pipe 401 and outer drill pipe 402, and connecting thread 404 for connecting between two adjacent sandwich drill pipes 4 is arranged at both ends of the inner drill pipe 401 and outer drill pipe 402, and the connecting thread 404 of both ends is respectively provided with internal thread and external thread, so that a plurality of sandwich drill pipes 4 are sequentially connected to form drill string, and drill tool 7 is installed at one end of drill string, and the drill tool 7 is communicated with the outer passage between inner drill pipe 401 and outer drill pipe 402, and safety valve is arranged in drill tool 7 or outer passage close to the end of drill tool, so that the water flow pressure in outer passage is not communicated with drill tool 7 when being lower than a certain value (A).

[0045] The radial drilling device 9 includes self-feeding drill bit 901, connecting hose 902, thrust water wheel 906, jet controller 907, flow distribution spring 908, flow sealing piston 909 and return one-way waterway valve 9012, the jet controller 907 is slidingly arranged in the outer drill pipe 402 and slidingly set on the inner drill pipe 401, and slides along the axial direction of the sandwich drill pipe under the push of water flow.

[0046] The flow sealing piston 909 is arranged in the outer drill pipe 402 and set on the inner drill pipe 401, and the end of the flow sealing piston 909 close to the drill tool 7 is fixedly connected with the outer drill pipe 402.

[0047] The end of the jet controller 907 close to the drill tool 7 is set on the flow sealing piston 909 and is in transition connection, and the flow distribution spring 908 arranged along the axial direction of the drill rod is arranged between the end close to the jet controller 907 and the flow sealing piston 909, so as to provide the jet controller 907 with reset elastic force away from the drill tool.

[0048] The end of the flow sealing piston 909 away from the drill tool is fixedly connected with the inner drill pipe 401 to form a sealed connection, and the inner cavity of the flow sealing piston 909 and the end close to the drill tool are both gap-connected with the inner drill pipe 401 to form a first waterway, and the flow hole 9091 is arranged on the flow sealing piston 909, and the flow ring groove 9072 corresponding to the flow hole 9091 is arranged on the jet controller 907, so that when the flow hole 9091 and the flow ring groove 9072 correspond, the first waterway is communicated with the inner cavity of the jet controller through the flow hole 9091 and the flow ring groove 9072.

[0049] The thrust water wheel 906 is arranged between the jet flow controller 907 and the inner drill pipe 401 and slides along the axial direction of the drill pipe under the pushing of water flow, and has a water passage hole for connecting the water passages on both sides of the thrust water wheel 906. One end of the connecting hose 902 is fixedly connected with the thrust water wheel 906, and the other end of the connecting hose 902 penetrates the jet flow controller 907 and the outer drill pipe 402 and is connected with the self-advancing drill bit 901 arranged on the outer side of the outer drill pipe 402 and along the radial direction, so as to provide high-pressure water for the self-advancing drill bit 901, and thus the self-advancing drill bit 901 drills along the radial direction in the main hole 5 to form the radial branch hole 8.

[0050] The return one-way water passage valve 9012 is arranged on the inner drill pipe 401 to connect the inner passage and the outer passage in the inner drill pipe 401, and is arranged at the end of the sealing piston 909 close to the drill pipe (the end away from the water inlet side), so that the water flow in the inner drill pipe 401 flows outward in the outer passage and then flows outward to the end away from the drill pipe through the first water passage, thereby driving the thrust water wheel 906 to slide to the end away from the drill pipe, and thus the connecting hose 902 and the self-advancing drill bit 901 in the radial branch hole 8 are retracted.

[0051] Further, the guiding protrusion 903 is arranged on the outer side of the outer drill pipe 402 to control the drilling direction of the self-advancing drill bit 901. The guiding protrusion 903 is provided with a strip-shaped hole for accommodating the guiding cantilever 904 and the rocker arm 905. The guiding cantilever 904 is hingedly connected with the guiding protrusion 903 at one end and is provided with a U-shaped groove at the other end, and the other end of the guiding cantilever 904 is hingedly connected with one end of the rocker arm 905 through the U-shaped groove. The other end of the rocker arm 905 is movably connected with the outer edge of the jet flow controller 907, so that the rocker arm 905 slides along with the jet flow controller 907, thereby driving the guiding cantilever 904 to protrude outward. The guiding cantilever 904 is provided with a first through hole 9041 for accommodating the connecting hose 902, so that the connecting hose 902 is connected with the self-advancing drill bit 901 through the first through hole 9041, thereby guiding the self-advancing drill bit 901 through the guiding cantilever 904 to control the drilling direction of the self-advancing drill bit 901.

[0052] Specifically, the movable connection between the rocker arm 905 and the jet flow controller 907 can be hinged connection. Alternatively, the movable connection between the rocker arm 905 and the jet flow controller 907 can be the meshing connection of a gear (the rocker arm 905) and a rack (the jet flow controller 907), and the end of the rocker arm 905 and the guiding protrusion 903 are slidingly hinged along the axial direction of the drill pipe (i.e., the hole for hingedly connecting the guiding protrusion 903 and the rocker arm 905 is a strip-shaped hole), thereby realizing the sliding of the rocker arm 905 along with the jet flow controller 907 and driving the guiding cantilever 904 to protrude outward.

[0053] Specifically, the jet flow controller 907 is provided with a second through hole 9071 for connecting the hose 902, a first sealing ring 9010 is arranged on the second through hole 9071 to prevent water from leaking from the second through hole 9071, and a second sealing ring 9011 is arranged at both ends of the outside of the jet flow controller 907 to form a sliding seal between the jet flow controller 907 and the outer drill pipe 402.

[0054] For reference Figure 6 The coal seam gas extraction radial multi-branch hole hydraulic jet rapid hole forming device further comprises a high-pressure water cart 1, a high-pressure water pipeline 2, a flow channel switching valve 3, and a drilling machine 10, wherein the drilling machine 10 is used for clamping the interlayer drill pipe 4 to drill the main hole 5 and drive the interlayer drill pipe 4 to advance or retreat to a specified position.

[0055] The high-pressure water cart 1 is connected to the flow channel switching valve 3 through the high-pressure water pipeline 2, and the flow channel switching valve 3 is connected to the end of the interlayer drill pipe 4 to input high-pressure water into the inner channel or the outer channel of the interlayer drill pipe 4. Specifically, the flow channel switching valve 3 has two water outlets matched with the interlayer drill pipe to respectively connect the inner channel and the outer channel of the interlayer drill pipe, and a three-way valve is further arranged on the water outlet connected to the outer channel to discharge the water flowing back through the three-way valve.

[0056] The working process of the above-mentioned coal seam gas extraction radial multi-branch hole hydraulic jet rapid hole forming device is as follows:

[0057] Step 1 (main hole construction process): The drilling machine 10 is used to cooperate with the interlayer drill pipe 4 to construct the main hole 5 in the coal seam 6 as a channel for the radial drilling device 9 to drill the radial branch hole 8, and the diameter of the main hole 5 is 50-113 mm, wherein the drilling machine 10 is a common drilling machine commonly used in coal mines.

[0058] Specifically, when the interlayer drill pipe 4 is used to construct the main hole 5, the water outlet of the flow channel switching valve 3 is connected to the outer channel of the interlayer drill pipe 4, and high-pressure water is sent into the outer channel, and the water pressure of the high-pressure water is set as A, so that the water pressure in the outer channel is greater than the threshold value of the safety valve in the drilling tool 7, and the pressure generated by the jet flow controller 907 in the radial drilling device 9 is less than the elastic force of the flow distribution spring 908, so that the water flow of the high-pressure water cart 1 flows out through the outer channel in the interlayer drill pipe and the drilling tool 7 to perform impact drilling of the main hole 5.

[0059] Step 2 (radial branch hole drilling process): when the main hole 5 is completed, the radial drilling device 9 installed on the sandwich drill pipe 4 is moved to the designated position by the directional drilling machine to drill the radial branch hole 8, at this time, the high-pressure water in the outer channel is continuously sent, and the water pressure of the high-pressure water is set to B, so that the pressure of the water flow in the outer channel on the jet controller 907 in the radial drilling device 9 is greater than the elastic force of the flow distribution spring 908, thereby making the jet controller 907 move towards the drilling device to compress the flow distribution spring 908, so that the flow ring groove 9072 is misaligned with the flow hole 9091, and the flow hole 9091 is closed through the transition connection between the jet controller 907 and the flow blocking piston 909, at the same time, the swing arm 905 connected with the jet controller 907 slides with the jet controller 907, the swing arm 905 drives the guide cantilever 904 to extend outward, and the connecting hose 902 and the self-advancing drill bit 901 connected at the end of the connecting hose 902 are taken out of the guide protrusion 903 and guided to the hole wall to form a specified angle, and the high-pressure water in the outer channel enters the high-pressure hose through the thrust water wheel 906, and forms a super-high pressure water jet under the action of the self-advancing drill bit 901 to drill the rock, at the same time, the thrust water wheel 906 is driven by the self-advancing drill bit 901 and the connecting hose 902 to move towards the drilling device to send out the connecting hose 902;

[0060] Step 3 (high-pressure hose and self-advancing drill bit retraction process): when a group of radial branch holes is completed, the flow channel switching valve 3 is controlled to connect the water outlet of the flow channel switching valve 3 with the inner channel of the sandwich drill pipe 4, and the outer channel of the sandwich drill pipe 4 is connected with the outer discharge channel of the drain valve or the three-way valve to discharge the backflow water in the outer channel of the sandwich drill pipe 4;

[0061] The water flow of the high-pressure water cart 1 flows into the inner channel of the sandwich drill pipe, and enters the outer channel of the sandwich drill pipe through the return one-way water valve 9012, and the water pressure of the high-pressure water is set to C, so that the water pressure in the outer channel is less than the threshold value of the safety valve in the drilling device 7, thereby making the water flow in the outer channel flow away from the drilling device (i.e. in the direction of the hole), and at this time, the pressure on the jet controller 907 is less than the elastic force of the flow distribution spring 908, so that the jet controller 907 and the swing arm 905 are reset, thereby making the flow ring groove 9072 correspond to the flow hole 9091, the flow hole 9091 is opened, the water flow in the outer channel flows into the jet controller 907 through the flow hole 9091, thereby driving the thrust water wheel 906 to move towards the hole, and the connecting hose 902 and the self-advancing drill bit 901 are driven out of the radial branch hole 8 by the thrust water wheel 906;

[0062] Step 4: cycle steps 2 and 3 to drill multiple groups of radial branch holes in the main hole 5, and after all the radial branch holes are completed, the sandwich drill pipe 4 is pulled out of the main hole 5 by the directional drilling machine to complete the construction.

[0063] Specifically, A is preferably 3-10 MPa, B is greater than 30 MPa, C is 2-8 MPa, and C is less than A, and A is less than B.

[0064] In another embodiment, the end of the sandwich drill pipe 4 is connected to a flow channel transition piece, the opening of one end of the flow channel transition piece is matched with the sandwich drill pipe 4, and the flow channel transition piece has an inner channel and an outer channel, and the other end is Y-shaped, which separates the inner channel and the outer channel into two independent channels (i.e. the inner channel is separated from the outer channel after penetrating through the outer channel), and is connected to the flow channel switching valve 3, and in this embodiment, the flow channel switching valve 3 has two water outlets to connect the inner channel and the outer channel of the flow channel transition piece independently, and a three-way valve is arranged on the independent outer channel to discharge the water flowing back from the outer channel of the sandwich drill pipe by switching the flow channel of the three-way valve.

[0065] Specifically, the high-pressure water cart 1 includes a high-pressure water pump 101, a high-pressure water tank 106, and a pressure regulating device 103, the water inlet of the high-pressure water pump 101 is connected to the high-pressure water tank 106, and the high-pressure water outlet 102 is connected to the pressure regulating device 103 and the high-pressure water pipeline 2 in sequence.

[0066] Preferably, the high-pressure water cart 1 further includes a remote pressure regulating device 105, and the remote pressure regulating device 105 is connected to the pressure regulating device 103 through a pressure regulating pipeline 104, so that the remote pressure regulating device 105 controls the pressure regulating device 103 through the pressure regulating pipeline 104, thereby realizing remote control of the pressure regulating device 103.

[0067] Preferably, the connecting hose 902 is at least one, and is uniformly arranged on the thrust water wheel 906 in the circumferential direction, and the number of corresponding guide protrusions 903 and self-advancing drill bits 901 corresponds to the number of connecting hoses 902; in this embodiment, preferably, the connecting hose 902 is four.

[0068] Specifically, in this embodiment, the high-pressure water pump 101, the high-pressure water outlet 102, the pressure regulating device 103, the pressure regulating pipeline 104, the remote pressure regulating device 105, the high-pressure water tank 106, the high-pressure water pipeline 2, the flow channel switching valve 3, the self-advancing drill bit 901 and the connecting hose 902 all adopt conventional devices in the prior art, which can meet the specified functions; wherein the self-advancing drill bit 901 can advance and break rocks under the action of high-pressure water without the need for additional thrust, and can adopt a conventional self-advancing nozzle in high-pressure water jet drilling technology.

[0069] Finally, it is to be explained that the above embodiments are only used to illustrate the technical solutions of the present application but not to limit the present application. Although the present application is described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical solutions of the present application can be modified or equivalently replaced without departing from the purpose and scope of the present application, and all should be covered in the scope of the claims of the present application.

Claims

1. A coal seam gas extraction radial multi-branch hole hydraulic jet rapid hole forming device, characterized in that: The radial drilling device comprises a self-advancing drill bit, a connecting hose, a thrust water wheel, a jet flow controller, a flow distribution spring, a flow sealing piston and a return one-way water path valve. The jet flow controller is slidingly arranged in the outer drill pipe and slidingly sleeved on the inner drill pipe and slides along the axial direction of the sandwich drill pipe under the thrust of water flow. The flow sealing piston is arranged in the outer drill pipe and sleeved on the inner drill pipe, and the end of the flow sealing piston close to the drill bit is fixedly connected with the outer drill pipe. The end of the jet flow controller close to the drill bit is sleeved on the flow sealing piston and is in transition connection, and a flow distribution spring arranged along the axial direction of the drill pipe is arranged between the end of the jet flow controller close to the drill bit and the flow sealing piston to provide a reset elastic force of the jet flow controller away from the drill bit. The end of the flow sealing piston away from the drill bit is fixedly connected with the inner drill pipe to form a sealed connection, and the inner cavity of the flow sealing piston and the end close to the drill bit are gap-connected with the inner drill pipe to form a first water path, and an overflow hole is arranged on the flow sealing piston, and an overflow ring groove corresponding to the overflow hole is arranged on the jet flow controller, so that when the overflow hole and the overflow ring groove correspond, the first water path is communicated with the inner cavity of the jet flow controller through the overflow hole and the overflow ring groove. The thrust water wheel is slidingly arranged between the jet flow controller and the inner drill pipe and slides along the axial direction of the drill pipe under the thrust of water flow, and has a water passage hole thereon to communicate the water paths on both sides of the thrust water wheel, one end of the connecting hose is fixedly connected with the thrust water wheel and is communicated with the water path on the side of the thrust water wheel away from the drill bit through the thrust water wheel, and the other end of the connecting hose penetrates through the jet flow controller and the outer drill pipe and is connected with the self-advancing drill bit arranged outside the outer drill pipe and along the radial direction to provide high-pressure water to the self-advancing drill bit to make the self-advancing drill bit drill along the main hole in the radial direction, thereby forming a radial branch hole. The return one-way water path valve is arranged on the inner drill pipe to communicate the inner channel and the outer channel in the inner drill pipe, and the return one-way water path valve is arranged at the end of the flow sealing piston close to the drill bit to make the water flow in the inner drill pipe flow to the outer channel in a one-way manner and flow to the end away from the drill bit through the first water path to drive the thrust water wheel to slide to the end away from the drill bit to retract the connecting hose and the self-advancing drill bit in the radial branch hole.

2. The coal seam gas extraction radial multi-branch hole hydraulic jet rapid hole forming device according to claim 1, characterized in that: A guide protrusion is arranged outside the outer drill pipe to control the drilling direction of the self-advancing drill bit.

3. The coal seam gas extraction radial multi-branch hole hydraulic jet rapid hole forming device according to claim 2, characterized in that: The guiding protrusion is provided with a strip-shaped hole for accommodating a guiding cantilever and a rocker arm, one end of the guiding cantilever is hingedly connected with the guiding protrusion, the other end of the guiding cantilever is provided with a U-shaped groove, and the U-shaped groove is hingedly connected with one end of the rocker arm, the other end of the rocker arm is movably connected with the outer edge of the jet flow controller, so that the rocker arm slides along with the jet flow controller, and in turn drives the guiding cantilever to protrude outward when the jet flow controller slides towards the drilling tool; The guiding cantilever is provided with a first through hole for accommodating a connecting hose, so that the connecting hose is connected with the self-advancing drill bit through the first through hole, and in turn the self-advancing drill bit is guided by the guiding cantilever to control the drilling direction of the self-advancing drill bit.

4. The coal seam gas extraction radial multi-branch hole hydraulic jet rapid hole forming device according to claim 3, characterized in that: The jet flow controller is provided with a second through hole for the connecting hose, and a first sealing ring is arranged on the connecting hose at the second through hole, so as to prevent water flow in the inner cavity of the jet flow controller from leaking from the second through hole.

5. The coal seam gas extraction radial multi-branch hole hydraulic jet rapid hole forming device according to claim 1, characterized in that: Second sealing rings are arranged at both ends of the outer side of the jet flow controller, so that the jet flow controller forms a sliding seal with the outer drill pipe.

6. The coal seam gas extraction radial multi-branch hole hydraulic jet rapid hole forming device according to claim 1, characterized in that: It also includes a high-pressure water cart, a high-pressure water pipeline, a flow channel switching valve, and a drilling machine for clamping the sandwich drill pipe to drill the main hole and driving the sandwich drill pipe to advance or retreat to a specified position. The high-pressure water cart is connected with the flow channel switching valve through the high-pressure water pipeline, and the flow channel switching valve is connected with the end of the sandwich drill pipe to input high-pressure water into the inner channel or the outer channel of the sandwich drill pipe and receive the backflow water in the outer channel.

7. The coal seam gas extraction radial multi-branch hole hydraulic jet rapid hole forming device according to claim 6, characterized in that: The flow channel switching valve has two water outlets matched with the sandwich drill pipe to respectively connect the inner channel and the outer channel of the sandwich drill pipe, and a three-way valve is further arranged on the water outlet connected with the outer channel to discharge the backflow water in the outer channel through the three-way valve.

8. The coal seam gas extraction radial multi-branch hole hydraulic jet rapid hole forming device according to claim 6, characterized in that: The high-pressure water cart includes a high-pressure water pump, a high-pressure water tank, and a pressure regulating device, the water inlet of the high-pressure water pump is connected with the high-pressure water tank, and the high-pressure water outlet is connected with the pressure regulating device and the high-pressure water pipeline in sequence.

9. The coal-bed gas extraction radial multi-branch hole hydraulic jet rapid hole- forming device according to claim 8, characterized in that: The high-pressure water cart further includes a remote pressure regulating device, the remote pressure regulating device is connected with the pressure regulating device through a pressure regulating pipeline, so that the remote pressure regulating device controls the pressure regulating device through the pressure regulating pipeline, and in turn realizes remote control of the pressure regulating device.

10. The coal seam gas extraction radial multi-branch hole hydraulic jet rapid hole forming device according to any one of claims 1-9, characterized in that: The connecting hose is at least one, and is uniformly arranged on the thrust water wheel in the circumferential direction, and the self-advancing drill bit corresponds to the connecting hose one by one.

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