Dual-power dual-tube shield pressure relief fluid slag removal drilling tool for deep coal seams

Abstract

The invention discloses a deep coal seam dual-power double-tube shield pressure relief fluid slag removal drill tool, the drill tool comprises an outer tube drill tool, an inner tube drill tool and a sliding support, the outer tube drill tool comprises a sieve hole drill rod and a hole-expanding drill bit, the inner tube drill tool comprises a special-shaped drill rod and an inner drill bit, the inner tube drill tool and the sliding support can be withdrawn from the inner cavity of the outer tube drill tool; the inner cavity of the special-shaped drill rod is a flow supply channel for providing fluid for drilling, and the space between the outer wall of the special-shaped drill rod and the inner wall of the sieve hole drill rod is an inner slag removal channel; the outer diameter of the sieve hole drill rod is equal to or smaller than the outer diameter of the hole-expanding drill bit, and the sieve hole drill rod plays a shielding role on the borehole wall; a plurality of slag discharge sieve holes are arranged in the spiral groove of the sieve hole drill rod, and the slag discharge sieve holes play a pressure relief role on the sieve hole drill rod; the dual-tube shield pressure relief fluid slag removal drill tool of the invention is used in conjunction with a dual-power head drilling rig, and is used for dual-power double-tube shield pressure relief straightening drilling and dual-power double-tube shield pressure relief directional drilling of deep protruding coal seam gas extraction drilling holes.

Description

Technical Field

[0001] The present invention relates to the technical field of coal mine gas extraction drilling, and in particular to a deep coal seam dual-power dual-tube shield pressure relief fluid slag removal drill tool, which is used for straight drilling and directional drilling of gas extraction boreholes that are difficult to form holes in deep protruding coal seams, soft-hard composite coal seams, broken soft coal seams, etc. Background Art

[0002] The drill rods used in the current deep protruding coal seams, soft-hard composite coal seams, and broken soft coal seams for gas extraction drilling construction are mostly grooved drill rods, ribbed drill rods, triangular grooved drill rods, triangular drill rods and other special-shaped drill rods. Among them, the patent applicants for the first three types of drill rods are the applicant, Henan Polytechnic University, and the patent numbers are ZL200610111830.7, ZL200920088879.4, and ZL200910064973.0 respectively. The common feature of these drill rods is that they use air flow, water flow or air-water linkage to discharge slag, and the annular space between the outer surface of the drill rod and the borehole wall is the slag discharge channel. Since the slag discharge channel is outside the drill rod, it is called the external slag discharge channel.

[0003] Deep coal seams have high ground stress, high gas content, and high gas pressure. Dynamic phenomena such as coal hole collapse, coal drilling, and coal and gas outbursts in the hole can all lead to collapse and blockage of the external slag discharge channel. The difficulty in slag discharge is the fundamental reason for the difficulty in drilling deep coal seams. When using an external slag discharge channel, the drill rod diameter must be smaller than the drill bit diameter. The disturbance space of the drill rod in the coal hole is large, and the straightening device lacks a stable support foundation in the coal hole and cannot be used normally, resulting in serious deviation of the coal seam drilling. The drilling trajectory encounters the coal seam roof or coal seam floor too early. The deviation of the drilling hole not only affects the drilling depth, but also subjects the drill rod to alternating stress, increasing the probability of drill breakage. Although the current screw motor directional drilling technology can solve the problem of coal hole deviation, the drilling depth in deep protruding coal seams is limited, and the cost of drilling and losing the drill is too high, so it is not suitable for use in protruding coal seams.

[0004] Double-tube drilling technology was used for drilling in shallow loose rock and soil layers in the last century. The double-tube internal circulation and outer-tube drill bits were used to protect the borehole from erosion damage and hole wall collapse. After the hole was formed, the inner-tube drill bit was first withdrawn, and then the buried wire pipe, pipeline, etc. were inserted into the hole through the outer-tube drill bit. Finally, the outer-tube drill bit was pulled out of the hole. Since the ground stress of shallow rock and soil is very small, the lifting and withdrawal of the outer-tube drill bit is easy to achieve. Therefore, double-tube drill bits are widely used in ground or shallow tunnel projects.

[0005] China Coal Technology and Engineering Group Xi'an Research Co., Ltd. undertook the National Science and Technology Major Special Funding Project "Research on Dual-Power Head and Dual-Tube Directional Drilling Technology and Equipment in Broken Soft Coal Seams" (Project No.: 2016ZX05045003-002), and carried out a lot of research on dual-power dual-tube drilling technology. The patents applied for and obtained include: "Coal Mine Underground Concentric Follow-up Tube Directional Drilling Device and Construction Method (ZL201610329723.5)", "A Double-Tube Automatic Loading and Unloading Device and Coal Mine Double-Power Head Drill (ZL201811424801.5)", "A Double-Tube Automatic Loading and Unloading Device and Coal Mine Double-Power Head Drill (ZL201811424801.5)", "A Double-Tube Peripheral Drilling Device for Offsetting Double-Tube Peripheral Drilling ... (ZL201811424801.5)", "A Double-Tube Peripheral Drilling Device for Offsetting Double-Tube Peripheral Drill (ZL201811 From the relevant academic papers published in this project, it is known that the use of dual-power head dual-tube directional drilling technology can successfully penetrate the protruding coal seam, leaving the outer tube in the protruding coal seam that is difficult to drill a hole. After the inner tube drill enters the coal seam roof rock, the construction of directional long drilling in the fracture zone is carried out, which overcomes the problem of successfully passing the protruding coal seam through the high-position fracture zone directional long drilling under the condition of multiple coal seams, which is of great significance. It is also known from the relevant papers published in this project that the use of dual-power head dual-tube directional drilling technology can greatly increase the drilling depth of coal holes in broken soft coal seams and protruding coal seam seam along-layer holes, greatly reducing the risk of expensive drilling tools such as the in-hole measurement system-screw motor being crushed and lost, which is of great significance and is also an effective means to solve the difficulty of drilling abnormal gas in protruding coal seams. However, due to the high ground stress in deep coal seams, it is highly likely that the outer pipe will be crushed during double-pipe drilling. Therefore, in the National Science and Technology Major Project "Research on Technology and Equipment of Double-Power Head Double-Pipe Directional Drilling in Broken Soft Coal Seams" (Project No.: 2016ZX05045003-002), in the test of drilling holes in the protruding coal seams, the outer pipe uses a high-strength PE plastic pipe that can be cut by a coal mining machine. The strength of the PE plastic outer pipe is limited and it is not a normal drill rod. The outer pipe drill tool follows the inner pipe drill tool to protect the hole. The outer pipe has a hole protection function but no pressure relief function. After the outer pipe is crushed and stuck, the outer pipe will lose the function of continuing to follow up and protect the hole. As mentioned above, if the inner pipe drill tool continues to drill forward, it will inevitably face the restraint of a longer and extremely unstable external slag discharge channel, thus restricting the final hole depth of the double-pipe double-power directional drilling in broken soft coal seams. Summary of the invention

[0006] The present invention aims at the problems existing in the existing dual-power dual-tube drilling: first, the ground stress of deep coal seams is high, and after the large-diameter PE outer tube is pressed and blocked too early, the outer tube will not be able to continue to follow up and protect the hole, which restricts the final hole depth of directional drilling in broken soft coal seams and reduces the drilling effect of dual-power dual-tube drilling; second, the large-diameter PE outer tube is left in the coal hole, which will not only greatly increase the construction cost of coal seam drilling, but also because the bulk density of PE plastic pipe is less than the bulk density of gangue ash in the coal seam, it is difficult to select PE materials during coal washing, which affects the coal quality of clean coal. The present invention changes the structural form of the outer tube, and the outer tube is referred to as the outer tube drilling tool in the present invention. The outer tube drilling tool consists of a sieve hole drill rod and a hole expansion drill bit. The sieve hole drill rod is made of special steel for drill rods. The sieve hole drill rod has a reverse spiral sieve hole structure, so that the sieve hole drill rod has the function of shielding the drilling hole and the function of self-pressure relief, so that the outer tube drilling tool is not easy to be pressed and blocked, and the outer tube can also be smoothly withdrawn from the borehole after the hole is formed.

[0007] The technical solutions adopted to achieve the above objectives are:

[0008] The deep coal seam dual-power double-tube shield pressure relief fluid slag removal drill tool comprises an outer tube drill tool, an inner tube drill tool and a sliding support that are inserted and installed; the outer tube drill tool comprises a plurality of sieve hole drill rods and a reaming drill bit; the inner tube drill tool comprises a plurality of special-shaped drill rods and an inner drill bit; the sliding support is installed in the inner cavity of the reaming drill bit by means of a shear pin, the special-shaped drill rod passes through the sieve hole drill rod, the sliding support and extends out of the reaming drill bit, that is, the special-shaped drill rod passes through the inner hole of the support ring of the sliding support, and the sliding support keeps the reaming drill bit and the special-shaped drill rod coaxial. The inner hole of the special-shaped drill rod is a flow channel for providing fluid for drilling, the annular space between the sieve hole drill rod and the special-shaped drill rod is the inner slag removal channel of the drill tool, and the annular space between the special-shaped drill rod and the borehole wall is the outer slag removal channel of the drill tool; the sieve hole drill rod is provided with a plurality of slag discharge sieve holes that are connected to the inner slag removal channel.

[0009] During drilling, the inner tube drill tool drills into the solid coal at the bottom of the hole, and the drill slag of the inner drill bit of the inner tube drill tool enters the inner slag discharge channel through the outer slag discharge channel and the sliding support. The outer tube drill tool closely follows the inner tube drill tool or performs follow-up hole expansion drilling at a distance. Using the current dual-power head drilling rig, the inner tube drill tool and the outer tube drill tool perform synchronous drilling or separate drilling. When withdrawing the drill, the withdrawal and lifting force of the inner tube drill tool cuts off the shear pin on the sliding support, and the inner tube drill tool and the sliding support are withdrawn from the inner cavity of the outer tube drill tool together with the sliding support.

[0010] Furthermore, the reaming drill bit of the outer tube drill tool maintains the same constant inner diameter as the sieve hole drill rod. The purpose of maintaining the constant inner diameter is to allow the inner tube drill tool to exit the inner cavity of the outer tube drill tool smoothly; the inner drill bit diameter of the inner tube drill tool is smaller than the inner diameter of the sieve hole drill rod, so that the inner drill bit can exit from the inner cavity of the sieve hole drill rod; the outer diameter of the sieve hole drill rod is equal to or smaller than the outer diameter of the reaming drill bit. In actual application, the radius difference δ between the reaming drill bit and the sieve hole drill rod is 0 to 10 mm. Under the action of coal seam ground stress, the deformation and necking of the borehole will automatically disappear, and the sieve hole drill rod will begin to contact the borehole wall. The sieve hole drill rod plays a shielding role on the borehole wall, which can prevent the collapse of the borehole wall. Because the sieve hole drill rod plays a shielding role on the borehole wall, resulting in severe wear on its surface, spraying, cladding and other wear-resistant treatments on the surface of the sieve hole drill rod are also within the protection scope of the present invention.

[0011] Furthermore, a spiral groove is provided on the surface of the sieve hole drill rod, and a plurality of slag discharge sieve holes are provided in the spiral groove. A tapered hole spiral lath is welded in the spiral groove provided with the slag discharge sieve holes. The minor diameter of the tapered hole is smaller than the diameter of the slag discharge sieve hole, and the major diameter of the tapered hole is equal to the diameter of the slag discharge sieve hole. The number of tapered holes on the tapered hole spiral lath is the same as the number of the slag discharge sieve holes and is one-to-one coaxially matched, so that the diameter of the slag inlet of the slag discharge sieve hole is smaller than the diameter of the slag outlet. The slag discharge sieve hole has a pressure relief effect on the sieve hole drill rod, and can prevent the sieve hole drill rod from being crushed to death. Experiments show that the slag discharge effect of the inverted cone slag discharge sieve hole is better than that of the straight hole and the step hole, but the processing efficiency and cost of the inverted cone slag discharge sieve hole are low. Therefore, the method of combining the cone hole spiral lath with the straight hole to make the entrance of the slag discharge sieve hole conical can also obtain a better slag discharge effect; the thickness of the cone hole spiral lath is less than the depth of the spiral groove. After the lath is welded, the groove still exists. The spiral groove has the function of gathering and transporting slag, which helps to improve the slag discharge efficiency. The higher the slag discharge efficiency, the better the pressure relief effect. In order to increase the rubbing and crushing slag function of the cone hole spiral lath facing the coal surface, methods such as indentation and spraying of wear-resistant particles can be implemented on the cone hole spiral lath, and the cone hole can be punched or drilled. Similar related auxiliary technologies are also within the protection scope of the present invention.

[0012] Furthermore, the sliding support is installed in the inner cavity of the reaming drill bit through a shear pin, and the sliding support includes a support ring and a plurality of support legs on the outer periphery of the support ring; in this embodiment, three support legs are provided on the support ring of the sliding support, and the sliding support is installed in the inner cavity of the reaming drill bit by using the shear pin, so the outer diameter of the support legs of the sliding support needs to be equal to the inner diameter of the reaming drill bit; the special-shaped drill rod passes through the inner hole of the support ring of the sliding support, so the inner hole diameter of the support ring needs to be equal to or greater than the outer diameter of the special-shaped drill rod, and the sliding support is used to keep the reaming drill bit and the special-shaped drill rod coaxial so that the outer tube drill tool follows the inner tube drill tool to implement double-tube drilling.

[0013] Furthermore, the support ring of the sliding support is provided with radial through holes or radial through grooves, and the diameter of the through holes or the width of the through grooves is not less than the radial distance between the outer arc of the support ring and the inner wall of the sieve hole drill rod, so that the special-shaped drill rod can crush the coal slag stuck in the sliding support. There are three channels between the outer surface of the sliding support and the inner wall of the reaming drill bit that are easily blocked by coal slag. The radial through holes or through grooves provided on the sliding support are used to make the large pieces of coal slag stuck in the sliding support contact with the special-shaped drill rod, and the grooves and convex ribs on the outer surface of the special-shaped drill rod are used to crush the large pieces of coal slag, thereby eliminating the clogging of coal slag at the sliding device. The sliding support can also adopt an outer cylindrical support ring, that is, the outer circle of the support ring contacts the inner wall of the reaming drill bit, and the arc support leg contacts the special-shaped drill rod, so that the reaming drill bit and the special-shaped drill rod remain coaxial, with similar effects, and also within the protection scope of the present invention.

[0014] Furthermore, when the inner tube drill tool is withdrawn from the inner cavity of the outer tube drill tool, the shear pin on the sliding support is sheared off by the retreat force of the inner drill bit, and the sliding support is withdrawn from the inner cavity of the outer tube drill tool together with the inner tube drill tool.

[0015] Furthermore, the sliding support is made of wear-resistant and friction-reducing material, preferably ductile iron or copper with good wear resistance; or wear-resistant and friction-reducing material is embedded in the inner hole of the sliding support; in order to prevent the sliding support from getting stuck when sliding out, the length of the sliding support needs to be greater than 0.6 times the diameter of the inner hole of the sieve hole drill rod. The sliding support is a reusable part, and the shear pin is a disposable consumable; the shear pin is made of soft metal material, and the shear pin should be able to resist the shear force generated by the rotation and movement of the special-shaped drill rod, axial water-coal slag impact, etc. If the inner tube drill tool has coal and gas protrusion in the hole during the solid coal drilling process, the sliding support will be subjected to a strong impact force, so the shear pin is designed to have a shear resistance greater than 10KN.

[0016] Furthermore, the special-shaped drill rod of the inner tube drill tool is a common special-shaped drill rod or a cable-through special-shaped drill rod, and the surface of the special-shaped drill rod is designed to be grooved, rib-shaped, or prismatically grooved, and the special-shaped structure on the surface is helpful for slag crushing and slag discharge. Most of these special-shaped structures on the surface of the drill rod are inventions of the applicant from 2006 to 2009. Similar special-shaped drill rods used in conjunction with the outer tube drill tool described in the present invention are also within the protection scope of the present invention. The special-shaped drill rod can also adopt double-wall drill rod. The double-wall drill rod is used as the drill rod of the inner tube drill tool in conjunction with the outer tube drill tool described in this application, and it is also within the protection scope of the present invention; the applicant has applied for patents: application number CN202111237232.5, a spiral drill rod with a circumferential flow shield and pressure relief screen hole for protruding coal seams; application number CN202111152968.2, a curved edge drill rod with a flow protection hole and pressure relief screen hole for protruding coal seams corners; application number CN202110903532.6, a large-diameter circumferential flow shield and pressure relief screen hole drill rod for protruding coal seams; application number CN2021110726041.9, a circumferential flow protection hole and pressure relief screen hole drill rod for protruding coal seams. These drill rods can be used as the drill rod of the inner tube drill tool in conjunction with the outer tube drill tool described in this application, and they are also within the protection scope of the present invention.

[0017] Furthermore, the inner drill bit of the inner tube drill tool adopts an ordinary drill bit, or a non-magnetic drill rod, a trajectory measuring instrument, a screw drill tool, and a directional drill bit are added to the front end of the special-shaped drill rod; the directional drill tool composed of the non-magnetic drill rod, the trajectory measuring instrument, the screw drill tool, and the directional drill bit, that is, the inner tube drill tool can implement conventional drilling and directional drilling, and the fluid of the present invention includes water flow and air flow. The present invention does not have any innovative content for the inner tube drill tool itself, but adds an outer tube drill tool with a special structure on the basis of the existing inner tube drill tool (including conventional drilling and directional drilling), and utilizes the shield pressure relief function of the outer tube drill tool and its reliable inner slag discharge channel to stabilize and shorten the unreliable outer slag discharge channel of the inner tube drill tool, thereby increasing the conventional drilling depth or directional drilling depth of the inner tube drill tool.

[0018] Furthermore, the outer tube drill tool adopts reverse rotation, the inner tube drill tool adopts forward rotation, the spiral groove on the sieve hole drill rod is a reverse spiral groove, and the corresponding tapered hole spiral lath is also a reverse spiral. The rotation direction of the spiral groove and the thread rotation direction of the outer tube drill tool are the same as the rotation direction of the outer tube drill tool, and the rotation direction of the spiral groove and the thread rotation direction of the inner tube drill tool are the same as the rotation direction of the inner tube drill tool. There are two benefits of this design. One is that it can prevent the drill rod from slipping out; the other is that it can increase the relative rotation between the special-shaped drill rod and the sieve hole drill rod, thereby improving the slag discharge efficiency of the inner slag discharge channel.

[0019] Furthermore, when the drilling tool adopts wind-driven slag removal, the outer wall of the special-shaped drill pipe or the inner wall of the sieve hole drill pipe is clad, sprayed, electroplated with brass and other spark-proof materials to prevent the outer wall of the special-shaped drill pipe from colliding with the inner wall of the sieve hole drill pipe and generating sparks. The collision between the outer wall of the special-shaped drill pipe and the inner wall of the sieve hole drill pipe is a high-probability event. This collision is conducive to the crushing and slag removal of the inner slag removal channel, but there are safety hazards in the case of wind-driven slag removal, so it is necessary to adopt surface treatment to prevent collision sparks. In order to solve the collision problem between the outer wall of the special-shaped drill pipe and the inner wall of the sieve hole drill pipe, an anti-collision copper ring can also be set on the outer circle of the special-shaped drill pipe to prevent collision sparks. An anti-collision support can also be installed on the special-shaped drill pipe so that the outer wall of the special-shaped drill pipe and the inner wall of the sieve hole drill pipe will not collide. The anti-collision copper ring and the anti-collision support will increase the slag removal resistance of the inner slag removal channel and reduce the loading and unloading efficiency of the drill pipe. The use of anti-collision copper rings or anti-collision supports and similar anti-collision spark methods are also within the protection scope of the present invention.

[0020] Furthermore, for a deep coal seam dual-power double-tube shield pressure relief fluid slag removal drill tool, if a high-pressure water jet nozzle controlled by a high-low pressure conversion valve is arranged between the inner drill bit of the inner tube drill tool and the special-shaped drill rod or between the bottom hole motor screw drill tool and the trajectory measuring instrument, and the high-pressure water jet is used to implement coal seam permeability enhancement measures such as hydraulic cavitation or hydraulic cutting on the borehole, due to the existence of the outer tube drill tool and the inner slag removal channel, the cavitation position is made as close as possible to the hole expansion drill bit and the length of the outer slag removal channel is shortened, so that the coal slag produced by punching or cutting is easier to discharge out of the hole. Similar to adding hydraulic cavitation and hydraulic cutting devices to the inner tube drill tool and using them in conjunction with the outer tube drill tool described in the present invention, it also falls within the protection scope of the present invention.

[0021] The beneficial effects of the present invention are:

[0022] 1. The outer tube drill tool (or outer tube) of the current double-tube dual-power drill tool only has a shielding function for the borehole wall, but no pressure relief function for the outer tube. Under the high ground stress of deep coal seams, it is highly likely that the outer tube will be crushed and lost, which restricts the hole protection follow-up depth of the outer tube drill tool, and thus also restricts the final hole depth of the inner tube drill tool. The outer tube drill tool described in the present invention is composed of a sieve hole drill rod and a hole expansion drill bit. The sieve hole drill rod has the function of shielding the borehole, and the slag discharge sieve hole has a pressure relief function for the sieve hole drill rod, so that the hole protection follow-up depth of the outer tube drill tool is deeper, which can increase the final hole depth of the inner tube drill tool, and can ensure that the outer tube drill tool can be smoothly lifted.

[0023] 2. The long-distance unstable external slag discharge channel is very easy to be blocked, which is the fundamental reason for the limited drilling depth of deep protruding coal seams. The external tube drill with shield pressure relief function and its reliable internal slag discharge channel can greatly shorten the length of the unstable external slag discharge channel, which can not only increase the depth of the final hole, but also provide support for the slag discharge problem of hydraulic cavitation and permeability enhancement in double-tube conventional drilling and double-tube directional drilling, and make it possible to promote the large-scale promotion of dual-power double-tube shield pressure relief directional drilling technology in the drilling construction of protruding coal seams.

[0024] 3. The annular inner slag discharge channel in the present invention is a steel sieve hole structure, and the inner slag discharge channel is stable and reliable. The coal slag is rubbed between the sieve hole drill rod and the special-shaped drill rod, which can break the slag particles and provide favorable coal slag transportation conditions for fluid slag discharge. It can ensure that the slag discharge of the inner slag discharge channel is smooth, realize high-efficiency slag discharge, and then eradicate the blockage and spray hole phenomenon in the hole.

[0025] 4. In the present invention, the outer diameter of the sieve hole drill rod is equal to or smaller than the outer diameter of the reaming drill bit. The sieve hole drill rod has a shielding effect on the borehole wall, which can prevent excessive collapse of the borehole wall. The slag discharge sieve hole has a pressure relief effect on the sieve hole drill rod, which can prevent the outer tube drill tool from being crushed to death, which can not only improve the quality of the hole, but also ensure that the outer tube drill tool can be smoothly withdrawn from the hole.

[0026] 5. When directional drilling is adopted in the present invention, the outer tube drill tool acts as a shield to relieve pressure on the main hole, which not only provides a safe passage for the withdrawal of the inner tube directional drill tool, but also the stability of the main hole provides favorable conditions for the inner tube directional drill tool to implement short-distance fixed drilling and short-distance branch drilling.

[0027] .Brief Description of the Figures

[0028] Figure 1 It is the overall scheme diagram of the deep coal seam dual-power dual-tube shield pressure relief fluid slag removal drilling tool of the present invention;

[0029] Figure 2 A diagram showing the connection between the reaming drill bit and the sliding support member of the invention;

[0030] Figure 3 It is a schematic diagram of the outer tube drilling tool of the present invention;

[0031] Figure 4 It is a schematic diagram of the inner tube drilling tool of the present invention;

[0032] Figure 5 It is a schematic diagram of the sieve plate strips of the present invention. DETAILED DESCRIPTION

[0033] The present invention is further described below in conjunction with the accompanying drawings.

[0034] A deep coal seam dual-power dual-tube shield pressure relief fluid slag removal drill tool comprises an outer tube drill tool, an inner tube drill tool and a sliding support member which are installed in a plug-in manner; Figure 1~Figure 4 As shown, the outer tube drill tool includes a plurality of sieve hole drill rods 1 and a reaming drill bit 2. Preferably, the reaming drill bit 2 adopts an ordinary hollow drill bit or a variable diameter drill bit; the inner tube drill tool includes a plurality of special-shaped drill rods 3 and an inner drill bit 4; the sliding support 5 is installed in the inner cavity of the reaming drill bit 2 by means of a shear pin 9, and the special-shaped drill rod 3 passes through the inner hole of the support ring of the sliding support 5. The sliding support 5 keeps the reaming drill bit 2 coaxial with the special-shaped drill rod 3.

[0035] like Figure 1 As shown, the inner hole of the special-shaped drill rod 3 is a flow supply channel 6 for providing fluid for drilling, the annular space 7 between the sieve hole drill rod 1 and the special-shaped drill rod 3 is an internal slag discharge channel of the drill tool, and the annular space between the special-shaped drill rod 3 and the borehole wall is an external slag discharge channel of the drill tool; a plurality of slag discharge sieve holes 10 connected to the internal slag discharge channel are arranged in the spiral groove 8 of the sieve hole drill rod 1.

[0036] When drilling, the inner tube drill tool drills toward the solid coal rock at the bottom of the hole, and the drill slag produced by the inner drill bit 4 of the inner tube drill tool enters the inner slag discharge channel 7 through the outer slag discharge channel and the sliding support 6. The outer tube drill tool closely follows the inner tube drill tool or performs follow-up hole expansion drilling at a distance. Using the current dual-power head drilling rig, the inner tube drill tool and the outer tube drill tool perform synchronous drilling or separate drilling. When withdrawing the drill, the withdrawal and lifting force of the inner tube drill tool shears off the shear pin 9 on the sliding support 5, and the inner tube drill tool and the sliding support 5 withdraw from the inner cavity of the outer tube drill tool together with the sliding support 5.

[0037] like Figure 3 As shown, the reaming drill bit 2 of the outer tube drill tool and the screen hole drill rod 1 maintain the same constant inner diameter. The purpose of maintaining the constant inner diameter is to allow the inner tube drill tool to exit smoothly from the inner cavity of the outer tube drill tool; Figure 1 As shown, the diameter of the inner drill bit 4 of the inner tube drill is smaller than the inner diameter of the sieve hole drill rod 1, so that the inner drill bit 4 can be withdrawn from the inner cavity of the sieve hole drill rod 1; the outer diameter of the sieve hole drill rod 1 is equal to or smaller than the outer diameter of the reaming drill bit 2. In actual application, the radius difference δ between the reaming drill bit 2 and the radius of the sieve hole drill rod 1 is 0-10mm. Under the action of coal seam ground stress, the deformation and necking of the borehole will automatically disappear, that is, the sieve hole drill rod 1 begins to contact the borehole wall, and the sieve hole drill rod 1 plays a shielding role on the borehole wall, which can prevent the collapse of the borehole wall. Because the sieve hole drill rod 1 plays a shielding role on the borehole wall, the wear on its surface is relatively serious. Wear-resistant treatment such as spraying and cladding is adopted on the surface of the sieve hole drill rod 1, which is also within the protection scope of the present invention.

[0038] like Figure 3As shown, the outer surface of the sieve hole drill rod 1 is provided with a spiral groove 8, and a plurality of slag discharge sieve holes 10 are provided in the spiral groove 8. A conical hole spiral strip 11 is welded in the spiral groove 8 provided with the slag discharge sieve holes 10. The conical hole strip 11 is as shown in FIG. Figure 5 As shown, the minor diameter of the conical hole 111 on the conical hole strip 11 is smaller than the diameter of the slag discharge screen hole 10, and the major diameter of the conical hole 111 is equal to the diameter of the slag discharge screen hole 10. The number of conical holes 111 on the conical hole spiral strip 11 is the same as the number of the slag discharge screen hole 10 and is one-to-one coaxially matched, so that the diameter of the slag inlet of the slag discharge screen hole 10 is smaller than the diameter of the slag outlet. The slag discharge screen hole 10 has a pressure relief effect on the screen hole drill rod 1, which can prevent the screen hole drill rod 1 from being crushed to death. Experiments show that the slag discharge effect of the inverted cone slag discharge screen hole is better than that of the straight hole, but the processing efficiency and cost of the inverted cone slag discharge screen hole are low. Therefore, the method of using the conical hole spiral strip and the straight hole to make the entrance of the slag discharge screen hole conical can also obtain a better slag discharge effect; the thickness of the conical hole spiral strip 11 is less than the depth of the spiral groove 8. After the strip is welded, there is still a groove. The spiral groove has the function of slag gathering and slag transportation, which helps to improve the slag discharge efficiency. The higher the slag discharge efficiency, the better the pressure relief effect. In order to increase the kneading and crushing function of the conical hole spiral lath 11 facing the coal surface, methods such as indentation and spraying of wear-resistant particles can be implemented on the conical hole spiral lath 11, and the conical hole 111 can be a punched conical hole or a drilled conical hole. Similar related auxiliary technologies are also within the protection scope of the present invention.

[0039] It should be noted that the support ring of the sliding support member 5 has three support legs 51, and the sliding support member 5 is installed in the inner cavity of the reaming drill bit 2 by using the shear pin 9. Therefore, the outer diameter of the support legs 51 of the sliding support member needs to be equal to the inner diameter of the reaming drill bit 2 (such as Figure 2 as shown); Figure 1 As shown, the special-shaped drill rod 3 passes through the inner hole of the sliding support 5, so the inner hole diameter of the support ring of the sliding support 5 is required to be equal to or larger than the outer diameter of the special-shaped drill rod 3. The sliding support 5 is used to keep the reaming drill bit 2 and the special-shaped drill rod 3 coaxial, so that the outer tube drill tool follows the inner tube drill tool to implement double-tube drilling.

[0040] like Figure 2As shown in (b), in this embodiment, the support ring 52 of the sliding support 5 is provided with a radial through hole 53 or a radial through groove, and the diameter of the through hole 53 or the width of the through groove is not less than the radial distance between the outer arc surface of the support ring 52 and the inner wall of the screen hole drill rod 1, so that the special-shaped drill rod 3 can crush the coal blocks stuck in the sliding support 5. There are three channels between the outer surface of the sliding support 5 and the inner wall of the reaming drill bit 2, which are easily blocked by coal slag. The radial through hole 53 or through groove provided on the sliding support 5 is used to make the large pieces of coal slag stuck in the sliding support 5 contact with the special-shaped drill rod 3, and the groove 8 and convex ribs on the outer surface of the special-shaped drill rod 3 are used to crush the large pieces of coal slag, so as to eliminate the blockage of coal slag at the sliding device. The sliding support 5 can also adopt an outer circle support ring, that is, the outer circle of the support ring contacts the inner wall of the reaming drill bit, and the arc support leg contacts the special-shaped drill rod, so that the reaming drill bit and the special-shaped drill rod remain coaxial, and the effect is similar, which is also within the protection scope of the present invention.

[0041] In the present invention, when the inner tube drill tool is withdrawn from the inner cavity of the outer tube drill tool, the shear pin 9 on the sliding support 5 is sheared off by the retreat force of the inner drill bit 4, and the sliding support 5 is withdrawn from the inner cavity of the outer tube drill tool together with the inner tube drill tool.

[0042] In this embodiment, the sliding support member 5 is made of wear-resistant and friction-reducing materials such as ductile iron, or made of copper with good wear resistance; or other wear-resistant and friction-reducing materials are embedded in the inner hole of the support ring of the sliding support member 5; in order to prevent the sliding support member 5 from getting stuck when sliding out, the length of the sliding support member 5 needs to be greater than 0.6 times the diameter of the inner hole of the sieve hole drill rod 1. The sliding support member 5 is a reusable part, and the shear pin 9 is a disposable consumable; the shear pin 9 is made of soft metal material, and the shear pin 9 should be able to resist the shear force generated by the rotation and movement of the special-shaped drill rod 3, axial water-coal slag impact, etc. If the inner tube drill bit has coal and gas protrusion in the hole during the solid coal drilling process, the sliding support member 5 will be subjected to a strong impact force, so the design shear resistance of the shear pin 9 should be greater than 10KN.

[0043] The special-shaped drill rod 3 of the inner tube drill tool can be a common special-shaped drill rod or a cable-through special-shaped drill rod. The surface of the special-shaped drill rod 3 is designed to be grooved, rib-shaped, or prismatically grooved, etc. The special-shaped structure on the surface is helpful for slag crushing and slag discharge. Most of these special-shaped structures on the surface of the drill rod are inventions of the applicant from 2006 to 2009. Similar special-shaped drill rods used in conjunction with the outer tube drill tool described in the present invention are also within the protection scope of the present invention.

[0044] The inner drill bit 4 of the inner tube drill tool can be a common drill bit, or a directional drill tool composed of a non-magnetic drill rod, a trajectory measuring instrument, a screw drill tool, and a directional drill bit can be added to the front end of the special-shaped drill rod, that is, the inner tube drill tool can implement conventional drilling or directional drilling, and the fluid includes water flow and air flow. The present invention does not have any innovative content on the inner tube drill tool itself, but adds a special structure of the outer tube drill tool on the basis of the existing inner tube drill tool (including conventional drilling and directional drilling), and utilizes the shield pressure relief function of the outer tube drill tool and its reliable inner slag discharge channel to stabilize and shorten the unreliable outer slag discharge channel of the inner tube drill tool, thereby increasing the conventional drilling depth or directional drilling depth of the inner tube drill tool.

[0045] The outer tube drill tool adopts reverse rotation, the inner tube drill tool adopts forward rotation, the spiral groove 8 on the sieve hole drill rod 1 is a reverse spiral groove, and the corresponding tapered hole spiral lath 11 is also a reverse spiral. There are two benefits of this design. One is that it can prevent the drill rod from slipping out; the other is that it can increase the relative rotation between the special-shaped drill rod and the sieve hole drill rod, thereby improving the slag discharge efficiency of the internal slag discharge channel.

[0046] When the drilling tool adopts pneumatic slag removal, the outer wall of the special-shaped drill rod 3 or the inner wall of the sieve hole drill rod 1 is clad, sprayed, electroplated with brass or other spark-proof materials to prevent the outer wall of the special-shaped drill rod 3 from colliding with the inner wall of the sieve hole drill rod 1 and generating sparks. The collision between the outer wall of the special-shaped drill rod 3 and the inner wall of the sieve hole drill rod 1 is a high-probability event, and such collision is conducive to the crushing and slag removal of the inner slag discharge channel 7, but there are safety hazards in the case of pneumatic slag removal, so it is necessary to adopt surface treatment to prevent collision sparks. In order to solve the collision problem between the outer wall of the special-shaped drill rod 3 and the inner wall of the sieve hole drill rod 1, an anti-collision copper ring can also be set on the outer circle of the special-shaped drill rod 3 to prevent collision sparks. An anti-collision support can also be installed on the special-shaped drill rod 3 to prevent the outer wall of the special-shaped drill rod 3 from colliding with the inner wall of the sieve hole drill rod 1. The anti-collision copper ring and the anti-collision support will increase the slag discharge resistance of the inner slag discharge channel and reduce the loading and unloading efficiency of the drill rod. The use of anti-collision copper rings or anti-collision supports and similar methods of preventing collision sparks are also within the protection scope of the present invention.

[0047] The deep coal seam dual-power double-tube shield pressure relief fluid slag removal drill tool, if a high-pressure water jet nozzle controlled by a high-low pressure conversion device is set between the inner drill bit 4 of the inner tube drill tool and the special-shaped drill rod 3, or between the screw drill tool and the trajectory measuring instrument, or at other positions of the inner tube drill tool, and the high-pressure water jet is used to implement hydraulic cavitation or hydraulic slitting and other coal seam permeability enhancement measures on the borehole. Due to the existence of the outer tube drill tool and the inner slag removal channel, the hydraulic cavitation or hydraulic slitting position can be made as close to the reaming drill bit as possible, thereby greatly shortening the length of the unstable external slag removal channel, making it easier to discharge the coal slag produced by punching or slitting out of the hole, which is also within the protection scope of the present invention.

[0048] This embodiment does not impose any formal limitation on the shape, material, structure, etc. of the present invention. Any simple modification, equivalent change and modification made to the above embodiments based on the technical essence of the present invention shall fall within the protection scope of the present invention.

[0049] In the description of the present invention, it is necessary to understand that the terms "center", "longitudinal", "lateral", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside" and the like indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the protection content of the present invention.

[0050] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein, but these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A deep coal seam dual-power dual-tube shield pressure relief fluid slag removal drill tool, characterized in that: It comprises an outer tube drill tool, an inner tube drill tool and a sliding support member that are inserted and matched, the outer tube drill tool comprises a plurality of screen hole drill rods and a reaming drill bit, the inner tube drill tool comprises a plurality of special-shaped drill rods and an inner drill bit, the sliding support member is installed in the inner cavity of the reaming drill bit, the special-shaped drill rods pass through the screen hole drill rods and the sliding support member and extend out of the reaming drill bit; The inner cavity of the special-shaped drill rod is a flow channel for providing fluid for drilling, the annular space between the sieve hole drill rod and the special-shaped drill rod is an inner slag discharge channel, and the annular space between the special-shaped drill rod and the borehole wall is an outer slag discharge channel of the inner tube drill tool, and the sieve hole drill rod is provided with a plurality of slag discharge sieve holes connected to the inner slag discharge channel; During drilling, the inner tube drill tool drills toward the coal rock at the bottom of the hole, and the outer tube drill tool closely follows the inner tube drill tool or performs follow-up hole expansion drilling at a distance. The existing dual-power head drilling rig is used to make the inner tube drill tool and the outer tube drill tool perform synchronous drilling or separate drilling; The reaming drill bit and the sieve hole drill rod maintain the same constant inner diameter, the inner drill bit diameter is smaller than the inner diameter of the sieve hole drill rod, the outer diameter of the sieve hole drill rod is equal to or smaller than the outer diameter of the reaming drill bit, and the sieve hole drill rod acts as a shield for the borehole wall to prevent the collapse of the borehole wall; The sliding support is installed in the inner cavity of the reaming drill bit through a shear pin, and the sliding support includes a support ring and three support legs located on the outer periphery of the support ring; The inner hole diameter of the support ring of the sliding support is equal to the outer diameter of the special-shaped drill rod, and the special-shaped drill rod passes through the inner hole of the support ring of the sliding support; When the inner tube drill tool is withdrawn from the inner cavity of the outer tube drill tool, the shear pin on the sliding support is sheared off by the retreat force of the inner drill bit, and the sliding support is withdrawn from the inner cavity of the outer tube drill tool together with the inner tube drill tool.

2. The deep coal seam dual-power dual-tube shield pressure relief fluid deslagging drilling tool according to claim 1 is characterized in that: When pneumatic slag removal is adopted, spark-proof material is installed on the outer wall of the special-shaped drill pipe or the inner wall of the sieve hole drill pipe to prevent the outer wall of the special-shaped drill pipe from colliding with the inner wall of the sieve hole drill pipe and generating sparks.

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