Local hole protection drilling tool for high-position directional hole of coal mine roof and construction method thereof

Abstract

The application discloses a coal mine underground roof high-position directional hole local hole protection drilling tool and a construction method thereof. The tool comprises a hollow casing pipe, a casing shoe arranged at an axial head end of the casing pipe, a centralizer, a hydraulic impactor, a straight screw motor, a pusher and a hole sweeping device which are sequentially and axially arranged in the casing pipe, a hole sweeping device body and a guider body which are sequentially and axially arranged, the guider body comprises a connecting section and a spherical section which are connected, a plurality of spiral wings are arranged on an outer wall of the spherical section, a spiral groove is formed between adjacent spiral wings, the connecting section can be inserted into or threadedly connected with the hole sweeping device body, high-pressure flushing medium flowing through an inner pipe body of the hole sweeping device can axially move a piston assembly, and then push a hole sweeping blade assembly to extend out of the first pipe body through a rectangular through hole, so that mechanical hole sweeping is realized; the high-pressure flushing medium flowing through the inner pipe body of the hole sweeping device can also be sprayed out through the rectangular through hole and a reverse jet hole, so that hydraulic hole flushing is realized.

Description

Technical Field

[0001] This invention relates to the field of directional drilling technology in underground coal mines, and in particular to a drilling tool for local protection of high-level directional holes in the roof of underground coal mines and its construction method. Background Technology

[0002] Borehole extraction is an important method for coal mine gas control in my country at present. High-level directional drilling of the roof is an important means of relieving gas pressure in the mining-affected zone of the working face. Compared with pre-drainage boreholes in the coal seam, high-level directional drilling of the roof has significant spatial displacement characteristics: it generally starts from the coal seam drilling site, penetrates the false roof and the immediate roof, and then enters the main roof, finally extending a long distance nearly horizontally within the target layer along the designed height. At the same time, in order to meet the needs of long-distance gas extraction, it is often required to maximize the diameter of the final borehole.

[0003] However, due to the complex lithology, low strength, and frequent development of weakly cemented rock layers in coal-rock interfaces, false roofs, and immediate roofs, the borehole wall stability in cross-strata sections is poor, especially under large-diameter drilling conditions, making drilling in these sections difficult. Simultaneously, when encountering geological anomalies such as faults and fracture zones in bedding sections, the mechanical disturbance of the drill bit and the hydraulic erosion of the flushing medium can reduce the strength of the borehole wall rock mass, inducing borehole wall collapse and causing abnormalities such as pump blockage and drill bit jamming. Ultimately, this results in low drilling efficiency, insufficient hole formation rate, and limited final hole diameter in high-level directional drilling. In severe cases, it can lead to drill bit jamming, drill bit burial, and drill bit breakage accidents, causing not only direct economic losses such as drill bit loss but also delaying the drilling period, affecting mine gas drainage succession, and hindering the orderly connection of working faces. Even if the hole is successfully formed, there is a high risk of hole collapse during the gas drainage stage, blocking the borehole drainage channel, restricting stable gas drainage, and posing a threat to mine safety.

[0004] In existing technologies, installing borehole casing is an effective method to prevent borehole wall collapse. However, current large-diameter borehole casings suffer from problems such as difficulty in lowering them and low construction efficiency, failing to provide effective support for the borehole wall in collapsed sections. The main reasons are as follows: First, high-level directional boreholes in the roof are often drilled at large upward angles. Conventional casing technology uses a method of lowering the casing, which requires overcoming the frictional resistance between the casing and the borehole wall, as well as the downward component of the casing's weight in the drilling direction, resulting in high resistance and low efficiency. Second, loose and fractured rock masses formed by borehole wall collapses in cross-layer sections and fault fracture zones accumulate inside the borehole, hindering the smooth lowering of the casing. Third, during the drilling of casing sections, there is a certain degree of straightness error, which also increases the resistance to pushing large-diameter casings down.

[0005] To address the aforementioned problems, the designers of this invention, through dedicated research and drawing upon years of practical experience in related fields, have proposed a drilling tool and construction method for high-level directional drilling of complex roof structures in coal mines, in order to overcome the technical shortcomings of conventional protective casings that are difficult to successfully lower into place. Summary of the Invention

[0006] To address the deficiencies and shortcomings of existing technologies, this invention provides a drilling tool for local protection of high-level directional holes in the roof of coal mines and its construction method. The drilling tool has a simple structure and is convenient and quick to use, solving the technical problem that conventional protection casings are difficult to lower into place smoothly in existing technologies, and improving the efficiency of lowering large-diameter protection casings.

[0007] To achieve the above objectives, the present invention adopts the following technical solution:

[0008] A drilling tool for partial protection of high-level directional holes in the roof of a coal mine includes a hollow casing and a casing shoe disposed at the axial head end of the hollow casing. A centralizer, a hydraulic impactor, a straight screw motor, a pusher, and a hole sweeper are sequentially connected along the axial direction from back to front inside the hollow casing.

[0009] The hole sweeper includes a hole sweeper body and a guide body connected from back to front. The guide body includes a connecting section and a spherical section connected together. Multiple spiral wings are provided on the outer wall of the spherical section, and spiral grooves are formed between adjacent spiral wings. The connecting section can be inserted into or threaded into the hole sweeper body.

[0010] The hole sweeper body includes an inner tube and an outer tube that are coaxially sleeved together. The outer tube includes a first tube and a second tube that are connected together. The second tube is fixedly connected to the inner tube.

[0011] Multiple reverse jet holes are formed circumferentially on the side wall of the first tube head end, and the acute angle between the axis of the reverse jet holes and the axis of the first tube is 30° to 60°; an installation cavity is formed between the first tube and the inner tube of the hole sweeper, and a piston assembly that can slide along the axial direction of the inner tube of the hole sweeper is provided in the installation cavity; the tail end of the piston assembly is connected to multiple limiting blocks arranged circumferentially along the inner tube of the hole sweeper.

[0012] Multiple rectangular through holes parallel to the axial direction are provided on the side wall of the tail end of the first tube. A hole-sweeping blade assembly is provided in the through holes. The head end of the hole-sweeping blade assembly is installed on the rear end face of the limiting block, and the tail end is installed on the front end face of the second tube.

[0013] The high-pressure flushing medium flowing through the inner tube of the hole sweeper can drive the piston assembly to move axially, thereby pushing the hole sweeping blade assembly to extend out of the first tube through the rectangular through hole, thus realizing mechanical hole sweeping;

[0014] The high-pressure flushing medium flowing through the inner tube of the hole sweeper can also be ejected through the rectangular through hole and the reverse jet hole to achieve hydraulic flushing.

[0015] The present invention also has the following technical features:

[0016] Specifically, the first tube contains a first inner cavity, a second inner cavity, and a third inner cavity arranged sequentially from back to front. The connection between the first inner cavity and the second inner cavity forms an annular first limiting step, and the connection between the second inner cavity and the third inner cavity forms a second limiting step.

[0017] The limiting block includes a limiting part and a connecting part that are integrally connected, and the connecting part extends into the first inner cavity. The piston assembly includes a piston body and a piston inner sleeve fitted on the outer side of the front end of the inner tube. The piston body includes a first piston connecting part and a second piston connecting part that are integrally connected from back to front. The first piston connecting part is fixedly connected to the limiting part. The head end of the second piston connecting part extends into the second inner cavity and the upper end face of the head end of the second piston connecting part is fitted against the inner wall of the second inner cavity. A return spring coaxial with the piston body is fixed in the gap between the inner wall of the connecting part and the outer wall of the second piston connecting part, and the head end of the return spring is connected to the lower end face of the second piston connecting part.

[0018] Furthermore, the hole-sweeping blade assembly includes a blade and a support rod. The head end of the blade is hinged to the limiting part, the tail end of the blade is hinged to the head end of the support rod, and the tail end of the support rod is hinged to the second tube body.

[0019] Furthermore, the sleeve shoe includes a hollow sleeve shoe body, the sleeve shoe body includes a sleeve shoe connector and a shoulder body connected from back to front, the front end face of the shoulder body is provided with multiple cutting teeth along the circumference, and multiple radial fan-shaped protrusions are evenly distributed on the inner circumference of the shoulder body, and a first slag return groove is formed between adjacent radial fan-shaped protrusions.

[0020] Furthermore, a guide platform is provided at the end of the radial fan-shaped boss away from the cutting teeth. The small-diameter end of the guide platform is connected to the radial fan-shaped boss, and the large-diameter end of the guide platform is connected to the sleeve shoe connector.

[0021] Furthermore, the pusher includes a hollow pusher body and a pusher connector disposed at the rear end of the hollow pusher body. Multiple radial pusher splines are evenly distributed on the outer circumferential surface of the pusher body. The radial pusher splines can be inserted and engaged with the first slag return groove. The pusher connector is threadedly connected to the straight screw motor.

[0022] Furthermore, the number of the first slag return grooves is three, the number of the radial push splines is six, and the angle of the central angle corresponding to the first slag return groove is greater than the angle of the central angle corresponding to the radial push splines.

[0023] The outer diameter of the radial push spline is smaller than the inner diameter of the hollow sleeve but larger than the inner diameter of the shoulder body.

[0024] Furthermore, the centralizer includes a centralizer female connector, a centralizer body, and a centralizer male connector that are integrally connected from back to front. The centralizer male connector is threadedly connected to the impactor female connector located at the rear end of the hydraulic impactor. Multiple spiral centralizer ridges are provided on the outer wall of the centralizer body, and a spiral channel is formed between adjacent centralizer ridges.

[0025] Furthermore, a transition joint is provided between the straight screw motor and the hydraulic impactor. The transition joint includes a transition joint body, and the outer walls at both ends of the transition joint body are respectively provided with connecting external threads for connecting the straight screw motor and the hydraulic impactor.

[0026] This invention also protects a construction method for a drilling tool for partial protection of high-level directional holes in the roof of a coal mine. The construction method, achieved using the aforementioned drilling tool, includes the following steps:

[0027] Step 1: Lower the assembled partial borehole protection tool into the borehole;

[0028] Step 2: Start the mud pump and pump high-pressure flushing medium into the local borehole protection tool through the drill pipe. The high-pressure flushing medium propels the local borehole protection tool forward in the preset drilling direction. During drilling, the high-pressure flushing medium flowing through the inner tube of the borehole cleaner flows out through the head of the inner tube and pushes the piston body to move axially. This pushes the borehole cleaning blade assembly to extend out of the first tube through the rectangular through hole, thus achieving mechanical borehole cleaning. Part of the high-pressure flushing medium flowing through the inner tube of the borehole cleaner enters the rectangular through hole through the gap between the piston body and the inner tube and is ejected, while part is ejected through the reverse jet hole, thus achieving hydraulic flushing.

[0029] Step 3: After completing the drilling operation, turn off the mud pump. The piston body will be reset under the action of the return spring. The hole sweeping blade assembly will be retracted into the rectangular through hole. After the piston body is reset, the reverse jet hole will be blocked, and the local hole protection drill bit will be retrieved.

[0030] Compared with the prior art, the beneficial technical effects of this invention are:

[0031] (1) The device of the present invention uses a hole sweeper set at the front end to push a large-diameter protective casing into the hole by pulling it at the front end. At the same time, a hydraulic impactor is set at the tail end of the device to apply a high-frequency impact load to the casing. This changes the shape and stress state of the casing when it is lowered by pushing it at the tail end in the prior art. It effectively alleviates the bending deformation of the casing under pressure and reduces the frictional resistance between the outer wall of the casing and the inner wall of the borehole. This makes it easier to lower the large-diameter protective casing and helps to ensure the casing lowering depth.

[0032] (2) During the casing lowering process, the device of this invention can transmit the rotational torque output by the drilling rig to the pusher through the hydraulic impactor and the outer shell of the straight screw drill bit. The pusher's external spline engages with the inner boss of the casing shoe, driving the casing assembly connected to the casing shoe to rotate, thus achieving rotary casing lowering. Simultaneously, the high-pressure fluid medium drives the straight screw motor to output rotational torque, driving the hole sweeper installed at the front end of the straight screw motor to rotate and sweep the hole, achieving high-speed hole sweeping under low-speed casing rotation. This reduces the rotational resistance during the lowering of large-diameter casing while improving the hole sweeping effect.

[0033] (3) The hole sweeper of the present invention controls the opening and closing of the hole sweeper blade assembly by the pressure of the high-pressure flushing medium and the spring pressure. Under the drive of the bottom hole power drill, it realizes synchronous hydraulic flushing and mechanical hole sweeping, which can efficiently break and remove the residual rock fragments in the hole. Moreover, the drill cuttings formed by hole sweeping can be reversed through the annular channel inside the casing with the fluid medium, ensuring the smooth passage of casing lowering and avoiding jamming during casing lowering.

[0034] (4) The method of the present invention combines hydraulic punching with mechanical sweeping, which improves the reliability of sweeping and the cleaning efficiency of drilling, and reduces the resistance of pushing large-diameter casing in high-level directional holes in the roof of coal mines. The construction process is simple and highly operable. Attached Figure Description

[0035] Figure 1 This is a schematic diagram of the overall structure of the device of the present invention;

[0036] Figure 2 This is a cross-sectional view of the hole cleaner of the present invention;

[0037] Figure 3 This is a diagram showing the state of the hole sweeper of the present invention when the hole sweeper blade assembly is open;

[0038] Figure 4 This is a cross-sectional view of the sleeve shoe of the present invention;

[0039] Figure 5 This is an assembly view of the pusher and the sleeve shoe of the present invention;

[0040] Figure 6This is a schematic diagram of the pusher of the present invention, wherein (a) is a front view and (b) is a sectional view;

[0041] Figure 7 This is a schematic diagram of the straight screw motor structure of the present invention;

[0042] Figure 8 This is a schematic diagram of the straightening device structure of the present invention.

[0043] Meaning of the symbols in the attached image:

[0044] 1-Hollow sleeve, 2-Bore sweeper, 3-Center, 4-Hydraulic impactor, 5-Straight screw motor, 6-Pusher, 7-Sleeve shoe;

[0045] 21-Scanner body, 22-Guide body;

[0046] 211-Inner tube of the hole sweeper, 212-Outer tube of the hole sweeper, 213-Reverse jet hole, 214-Piston assembly, 215-Limiting block, 216-Sweeping blade assembly;

[0047] 2121-First tube body, 2122-Second tube body; 2141-Piston inner sleeve, 2142-First piston connecting part, 2143-Second piston connecting part, 2144-Return spring; 2151-Limiting part, 2152-Connecting part, 2161-Blade wing, 2162-Support rod;

[0048] 221-Connecting segment, 222-Spherical segment;

[0049] 2221-Propeller;

[0050] 31-Stabilizer female connector, 32-Stabilizer body, 33-Stabilizer male connector;

[0051] 321-Spiral straightening edge;

[0052] 61-Hollow actuator body; 62-Push connector;

[0053] 611 - Radial push spline;

[0054] 71-Sleeve shoe connector, 72-Shoulder body, 73-Cutting teeth;

[0055] 721 - Radial fan-shaped boss, 722 - Guide platform, 723 - First slag return channel.

[0056] The present invention will be described in detail below with reference to the accompanying drawings and specific embodiments. Detailed Implementation

[0057] It should be noted that all components used in this invention, unless otherwise specified, are components known in the art.

[0058] The terms "upper," "lower," "front," "rear," "top," and "bottom," etc., used in this invention to indicate orientation or positional relationships are merely for the convenience of describing the invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. "Inner" and "outer" refer to the inner and outer contours of the corresponding components, and should not be construed as limitations on the invention. In this invention, "front" and "rear" are as follows... Figure 1 As shown in the description, the front end corresponds to the header, and the back end corresponds to the tail end.

[0059] Furthermore, the terms "first," "second," and other ordinal numbers are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Therefore, a feature specified as "first" or "second" may explicitly or implicitly include one or more of that feature.

[0060] In this invention, unless otherwise stated, the terms "installation," "connection," "linking," and "fixing" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0061] Following the above technical solutions, specific embodiments of the present invention are given below. It should be noted that the present invention is not limited to the following specific embodiments, and all equivalent modifications made based on the technical solutions of this application fall within the protection scope of the present invention.

[0062] Example 1:

[0063] like Figure 1 As shown, this embodiment provides a drilling tool for partial protection of high-level directional holes in the roof of a coal mine, including a hollow casing 1 and a casing shoe 7 disposed at the axial head end of the hollow casing 1. A centralizer 3, a hydraulic impactor 4, a straight screw motor 5, a pusher 6, and a hole sweeper 2 are sequentially connected in the hollow casing 1 from back to front along the axial direction. The hole sweeper 2 can pass through the casing shoe 7 when not in operation, while the pusher 6 cannot pass through the casing shoe 7.

[0064] like Figure 2 and Figure 3As shown, the borehole sweeper 2 includes a borehole sweeper body 21 and a guide body 22 connected from back to front. The guide body 22 includes a connecting section 221 and a spherical section 222 connected together. Multiple spiral blades 2221 are provided on the outer wall of the spherical section 222, and spiral grooves are formed between adjacent spiral blades 2221. The outer diameter of the spherical section 222 is larger than the outer diameter of the borehole sweeper body 21, and the outer diameter of the connecting section 221 is smaller than the inner diameter of the front end of the borehole sweeper body 21. Therefore, the connecting section 221 can be inserted into or threaded into the borehole sweeper body 21. The guide body 22 is used to guide the borehole sweeper body 21 to move along the drilling trajectory. The spiral grooves help guide the residual rock cuttings in the borehole to move towards the borehole sweeper body 21.

[0065] The straight screw motor 5 is used to output torque and speed under the driving action of high-pressure flushing medium, driving the hole sweeper 1 to rotate, so as to realize the advanced high-speed rotation of the hole sweeper to sweep holes when the casing does not rotate or rotates at low speed.

[0066] like Figure 7 As shown, the straight screw motor 5 includes a front connector 51 and a rear connector 52 respectively provided with positive internal threads, and a screw motor body 53 disposed between the front connector 51 and the rear connector 52. The front connector 51 is connected to the drive shaft of the straight screw motor and can rotate with the drive shaft.

[0067] The front side of the screw motor body 53 is designed with a thickened body 54, and the surface of the thickened body 54 is machined with positive thread.

[0068] The hydraulic impactor 4 is used to generate axial impact load, and then the impact load is transmitted to the sleeve 8 in sequence through the straight screw motor 4, pusher 5, and sleeve shoe 2, so as to achieve axial drag reduction during the lowering of the sleeve 8.

[0069] The casing shoe 7 is used to axially limit the pusher 6 and effectively transmit the jacking force, impact force and rotational torque generated by the drill pipe, hydraulic impactor 4 and straight screw motor 5 connected to the drill string, respectively.

[0070] like Figure 2 As shown, the hole cleaner body 21 includes an inner tube 211 and an outer tube 212 coaxially sleeved. The outer tube 212 includes a first tube 2121 and a second tube 2122 connected together. The second tube 2122 is fixedly connected to the inner tube 211, and a hole cleaner connector is provided at the tail end of the second tube 2122.

[0071] Multiple reverse jet holes 213 are formed circumferentially on the side wall of the head end of the first tube 2121. In this embodiment, preferably, there are 6 reverse jet holes 213, which are evenly spaced along the circumference of the first tube 2121. The acute angle between the axis of the reverse jet hole 213 and the axis of the first tube 2121 is 45°. The setting of the inclination angle of the reverse jet hole 213 can ensure that when the high-pressure flushing medium flows through the reverse jet hole 213 during use, it can form a jet with a certain speed and direction, which helps the rock cuttings to move towards the borehole opening. An installation cavity is formed between the first tube 2121 and the inner tube 211 of the borehole cleaner. A piston assembly 214 that can slide along the axial direction of the inner tube 211 of the borehole cleaner is provided in the installation cavity. The tail end of the piston assembly 214 is connected to multiple limiting blocks 215 arranged circumferentially along the inner tube 211 of the borehole cleaner.

[0072] Multiple rectangular through holes parallel to the axial direction are provided on the tail end side wall of the first tube body 2121. In this embodiment, preferably, the number of rectangular through holes corresponds to the number of reverse jet holes 213, which is also 6, and they are arranged at equal intervals along the circumference of the first tube body 2121. A hole-sweeping blade assembly 216 is provided in the through holes. The head end of the hole-sweeping blade assembly 216 is installed on the rear end face of the limiting block 215, and the tail end is installed on the front end face of the second tube body 2122.

[0073] The high-pressure flushing medium flowing through the inner tube 211 of the hole sweeper can enter the cavity between the first outer tube 2121, the piston assembly 214, and the inner tube 211 of the hole sweeper, pushing the piston assembly 214 to move axially backward, thereby pushing the six hole sweeping blade assemblies 216 to extend out of the first tube 2121 through the six corresponding rectangular through holes. The outer diameter of the hole sweeping blade assembly 216 after opening is smaller than the borehole diameter. The rotation of the hole sweeping blade assembly 216 can sweep away the drill cuttings accumulated in the borehole, realizing mechanical hole sweeping. At this time, the piston assembly 214 no longer blocks the reverse jet hole 213. The high-pressure flushing medium flowing through the inner tube 211 of the hole sweeper can be partially ejected through the rectangular through hole and partially ejected through the reverse jet hole 213, realizing dual hydraulic flushing.

[0074] As a preferred embodiment, the first tube 2121 is provided with a first inner cavity, a second inner cavity and a third inner cavity connected sequentially from back to front. The connection between the first inner cavity and the second inner cavity forms an annular first limiting step, and the connection between the second inner cavity and the third inner cavity forms a second limiting step.

[0075] The limiting block 215 includes a limiting part 2151 and a connecting part 2152 that are integrally connected. The connecting part 2152 extends into the first inner cavity. The first limiting step is used to limit the axial movement of the connecting part 2152, and the second limiting step is used to limit the movement of the connecting section 221.

[0076] Piston assembly 214 includes a piston body and a piston inner sleeve 2141 fitted onto the outer side of the front end of the inner tube. A sealing ring is also fitted onto the outer wall of the piston inner sleeve 2141. The piston body includes a first piston connecting part 2142 and a second piston connecting part 2143 integrally connected from back to front. The first piston connecting part 2142 and the limiting part 2151 are fixedly connected by fastening bolts. The head end of the second piston connecting part 2143 extends into the second inner cavity, and the upper end face of the head end of the second piston connecting part 2143 is in contact with the inner wall of the second inner cavity. The connection is configured such that a return spring 2144, coaxial with the piston body, is fixed in the gap between the inner wall of the connecting part 2152 and the outer wall of the second piston connecting part 2143. The head end of the return spring 2144 is connected to the lower end face of the second piston connecting part 2143. When the piston body moves axially backward under the push of the high-pressure flushing medium, the return spring 2144 is compressed. When the piston body is no longer under the pressure of the high-pressure flushing medium, the return spring 2144 returns axially, causing the hole-sweeping blade assembly 216 to retract and return to the rectangular through hole.

[0077] As a preferred embodiment, the hole-sweeping blade assembly 216 includes a blade 2161 and a support rod 2162. The head end of the blade 2161 is hinged to the limiting part 2151, the tail end of the blade 2161 is hinged to the head end of the support rod 2162, and the tail end of the support rod 2162 is hinged to the second tube body 2122.

[0078] As a preferred embodiment of this invention, such as Figure 4 and Figure 5 As shown, the casing shoe 7 includes a hollow casing shoe body, which includes a casing shoe connector 71 and a shoulder body 72 connected from back to front. Multiple cutting teeth 73 are arranged circumferentially on the front end face of the shoulder body 72. The cutting teeth 73 can effectively repair irregular hole walls and effectively increase the lowering depth of the casing assembly. Multiple radial fan-shaped protrusions 721 are evenly distributed on the inner circumference of the shoulder body 72, and a first slag return groove 723 is formed between adjacent radial fan-shaped protrusions 721.

[0079] In a preferred embodiment, a guide platform 722 is provided at the end of the radial fan-shaped boss 721 away from the cutting tooth 73. The small-diameter end of the guide platform 722 is connected to the radial fan-shaped boss 721, and the large-diameter end of the guide platform 722 is connected to the sleeve shoe connector 71. The function of the guide platform 722 is to guide the push spline 611 to smoothly connect into the first slag return groove 723 of the sleeve shoe.

[0080] As a preferred embodiment of this invention, such as Figure 6As shown, the pusher 6 includes a hollow pusher body 61 and a pusher connector 62 disposed at the rear end of the hollow pusher body 61. Multiple radial pusher splines 611 are evenly distributed on the outer circumferential surface of the pusher body 61. The radial pusher splines 611 can be inserted and engaged with the first slag return groove 723. The pusher connector 62 is threadedly connected to the straight screw motor 5.

[0081] The rotational torque output by the pusher drill rig can be transmitted through the hydraulic impactor 6 and the straight screw drill 5. It also drives the hollow casing 2 connected to the casing shoe 7 to rotate through the external spline 611 of the pusher and the radial fan-shaped boss 721, realizing the rotational lowering of the casing. At the same time, the straight screw motor 5 is driven by the high-pressure fluid medium to output rotational torque, which drives the hole sweeper 1 installed at the front end of the straight screw motor 5 to rotate and sweep the hole. This enables the hole sweeper 1 to advance the hole at high speed while the hollow casing 2 rotates at low speed, thereby effectively reducing the rotational resistance during the lowering of the large-diameter casing and improving the advance hole sweeping effect.

[0082] As a preferred embodiment, there are three first slag return grooves 723 and six radial push splines 611. The angle of the central angle corresponding to the first slag return groove 723 is greater than the angle of the central angle corresponding to the radial push spline 611. The outer diameter of the radial push spline 611 is smaller than the inner diameter of the hollow sleeve 1 and larger than the inner diameter of the shoulder body 72.

[0083] After the radial push spline 611 can be inserted and engaged with the first return slag groove 723, the radial push spline 611 and the first return slag groove 723 partially overlap. The non-overlapping part of the first return slag groove 723 becomes the return channel of the high-pressure flushing medium. In this embodiment, three high-pressure flushing medium return channels are formed, which are equally spaced along the circumference of the pusher.

[0084] As a preferred embodiment, the centralizer 3 includes a centralizer female connector 31, a centralizer body 32, and a centralizer male connector 33, which are integrally connected from back to front. The centralizer male connector 33 is threadedly connected to the impactor female connector located at the rear end of the hydraulic impactor 4. The centralizer body 32 has a plurality of spiral centralizing ridges 321 on its outer wall, and a spiral channel is formed between adjacent centralizing ridges 321, which is used as a discharge channel for the high-pressure flushing medium and the slag.

[0085] As a preferred embodiment, a transition joint is provided between the straight screw motor 5 and the hydraulic impactor 4. The outer walls of both ends of the transition joint are respectively provided with connecting external threads for connecting the straight screw motor 5 and the hydraulic impactor 4.

[0086] The working principle of the device of the present invention is as follows:

[0087] The drill string is lowered into the borehole, rotated, and the mud pump is started to output high-pressure flushing medium. The flushing medium passes sequentially through the centralizer 3, hydraulic impactor 4, straight screw motor 5, and pusher 6 into the borehole cleaner 2. The high-pressure flushing medium enters the cavity between the first outer tube 2121, piston assembly 214, and inner tube 211 of the borehole cleaner, pushing the piston assembly 214 to move axially backward. This, in turn, pushes the borehole cleaner blade assembly 216 out of the first tube 2121 through the corresponding rectangular through hole. After the borehole cleaner blade assembly 216 opens... Driven by the rotation of the hydraulic impactor, the drill cuttings accumulated in the borehole are swept away, achieving mechanical hole sweeping; the piston assembly 214 no longer blocks the reverse jet hole 213, and the high-pressure flushing medium flowing through the inner tube 211 of the hole sweeper can be partially ejected through the rectangular through hole and partially ejected through the reverse jet hole 213, achieving dual hydraulic flushing. The returned high-pressure flushing medium and return slag enter the inner cavity between the tube string formed by the hollow sleeve 2, the hydraulic impactor 4, and the straight screw motor 5 through the first return slag groove 723, and finally flow out through the spiral groove.

[0088] The device of this invention is a purely mechanical structure, which is relatively simple and highly reliable. It enables the smooth lowering of large-diameter protective sleeves and solves the problems of high difficulty and low efficiency in lowering large-diameter protective sleeves in the prior art.

[0089] Example 2

[0090] This embodiment provides a construction method for a drilling tool for partial protection of high-level directional holes in the roof of a coal mine. The construction method is achieved using the aforementioned drilling tool for partial protection of high-level directional holes in the roof of a coal mine, and includes the following steps:

[0091] Step 1: Lower the assembled partial borehole protection tool into the borehole;

[0092] Specifically, it includes the following sub-steps:

[0093] Step 1.1, according to Figure 1 As shown, the hole sweeper 2, pusher 6, straight screw motor 5, transition joint, hydraulic impactor 4 and centralizer 3 are connected in sequence to form a drill string assembly, which is connected to the front end of the drill pipe.

[0094] Step 1.2: Connect the multiple hollow casings 1 connected together with the casing shoe 7 to form a casing assembly; insert the drill assembly into the casing assembly, so that the hole sweeper 2 passes through the center of the thickened shoulder body 72 of the casing shoe 7, and at the same time, let the radial pushing spline 611 of the pusher 6 be inserted into the radial fan-shaped boss 721 of the casing shoe 7 and abut against the end face of the shoulder body 72.

[0095] Step 1.3: Adjust the drilling rig so that the centerline of the drill assembly, the centerline of the casing assembly and the centerline of the borehole are basically aligned. Operate the drilling rig to provide feed force to the drill assembly, and use the drill assembly to push the assembled casing assembly to the borehole opening, and make the casing shoe 7 completely enter the hole.

[0096] Step 2: Start the mud pump and pump high-pressure flushing medium with a pressure not lower than the sum of the working pressures of the hydraulic impactor 4, the straight screw motor 5, and the hole sweeper 2 into the local hole protection tool through the drill pipe. The high-pressure flushing medium sequentially enters the connected hydraulic impactor 4 and straight screw motor 5, driving the hydraulic impactor 4 to generate and output impact load, and driving the straight screw motor 5 to generate and output rotational torque. The high-pressure flushing medium flows into the hole sweeper 2, flows out through the head of the inner tube 211, and pushes the piston body 2143 to move axially, thereby pushing the hole sweeper blade assembly 21. 6. The first tube extends out through the rectangular through hole, and the hole sweeper 2 is driven by the straight screw motor 5 to rotate at a speed of R1 to form a mechanical hole sweep. As the piston body 2143 moves axially, the jet hole 213 and the annular gap between the piston body and the inner tube are opened. The high-pressure flushing medium enters the rectangular through hole through the gap between the piston body and the inner tube and is ejected, while the medium is ejected through the reverse jet hole to form a hydraulic flush. Under the action of hydraulic flush and mechanical hole sweep, the drill cuttings flow into the inner annulus of the casing with the flushing medium through the return slag groove 723 and return out of the hole.

[0097] At the same time, the drilling rig drives the local hole protection drill bit to rotate and advance along the edge of the hole to be lowered casing through the drill rod at a speed of R2, which drives the casing assembly to rotate into the hole. The rotation speed of the hole cleaner 2 is equal to the sum of the rotation speed R2 of the drilling rig and the rotation speed R1 generated by the straight screw motor 5.

[0098] Step 3: After completing the drilling operation, turn off the mud pump. The piston body will be reset under the action of the return spring. The hole sweeping blade assembly will be retracted into the rectangular through hole. After the piston body is reset, the reverse jet hole will be blocked, and the local hole protection drill bit will be retrieved.

[0099] The method of this invention uses a high-pressure flushing medium to propel the local borehole protection drill bit forward along a preset drilling direction. During the drilling process, it combines hydraulic flushing with mechanical sweeping, thereby improving the reliability and efficiency of sweeping and reducing the resistance of lowering and pushing large-diameter casings in high-level directional holes in the roof of coal mines. This construction process is simple and highly operable.

[0100] The specific technical features described in the above embodiments can be combined in any suitable manner without contradiction, as long as they do not violate the spirit of the present invention, and should also be regarded as the content disclosed by the present invention.

Claims

1. A drilling tool for partial protection of high-level directional holes in the roof of a coal mine, comprising a hollow casing (1), characterized in that, It also includes a sleeve shoe (7) set at the axial head end of the hollow sleeve (1), and a centralizer (3), a hydraulic impactor (4), a straight screw motor (5), a pusher (6) and a hole sweeper (2) are sequentially connected in the hollow sleeve (1) from back to front along the axial direction. The hole cleaner (2) includes a hole cleaner body (21) and a guide body (22) connected from back to front. The guide body (22) includes a connecting section (221) and a spherical section (222) connected together. Multiple spiral wings (2221) are provided on the outer wall of the spherical section (222), and a spiral groove is formed between adjacent spiral wings (2221). The connecting section (221) can be inserted into or threaded into the hole cleaner body (21). The hole cleaner body (21) includes an inner tube (211) and an outer tube (212) coaxially sleeved together. The outer tube (212) includes a first tube (2121) and a second tube (2122) connected together. The second tube (2122) is fixedly connected to the inner tube (211). The first tube (2121) has multiple reverse jet holes (213) circumferentially opened on the side wall of its head end. The acute angle between the axis of the reverse jet holes (213) and the axis of the first tube (2121) is 30°~60°. An installation cavity is formed between the first tube (2121) and the inner tube (211) of the hole sweeper. A piston assembly (214) that can slide along the axial direction of the inner tube (211) of the hole sweeper is provided in the installation cavity. The tail end of the piston assembly (214) is connected to multiple limiting blocks (215) arranged circumferentially along the inner tube (211) of the hole sweeper. Multiple rectangular through holes parallel to the axial direction are provided on the tail end side wall of the first tube (2121). A hole-sweeping blade assembly (216) is provided in the through holes. The head end of the hole-sweeping blade assembly (216) is installed on the rear end face of the limiting block (215), and the tail end is installed on the front end face of the second tube (2122). The high-pressure flushing medium flowing through the inner tube (211) of the hole sweeper can push the piston assembly (214) to move axially, thereby pushing the hole sweeping blade assembly (216) to extend out of the first tube (2121) through the rectangular through hole, thus realizing mechanical hole sweeping; The high-pressure flushing medium flowing through the inner tube (211) of the hole sweeper can also be ejected through the rectangular through hole and the reverse jet hole (213) to achieve hydraulic flushing.

2. The drilling tool for local protection of high-level directional holes in the roof of a coal mine as described in claim 1, characterized in that, The first tube (2121) is provided with a first inner cavity, a second inner cavity and a third inner cavity connected in sequence from back to front. The connection between the first inner cavity and the second inner cavity forms an annular first limiting step, and the connection between the second inner cavity and the third inner cavity forms a second limiting step. The limiting block (215) includes a limiting part (2151) and a connecting part (2152) that are integrally connected, and the connecting part (2152) extends into the first inner cavity; The piston assembly (214) includes a piston body and a piston inner sleeve (2141) fitted on the outer side of the front end of the inner tube. The piston body includes a first piston connecting part (2142) and a second piston connecting part (2143) integrally connected from back to front. The first piston connecting part (2152) is fixedly connected to the limiting part (2151). The head end of the second piston connecting part (2143) extends into the second inner cavity and the upper end face of the head end of the second piston connecting part (2143) fits against the inner wall of the second inner cavity. A return spring (2144) coaxial with the piston body is fixed in the gap between the inner wall of the connecting part (2152) and the outer wall of the second piston connecting part (2143), and the head end of the return spring (2144) is connected to the lower end face of the second piston connecting part (2143).

3. The drilling tool for local protection of high-level directional holes in the roof of a coal mine as described in claim 2, characterized in that, The hole-sweeping blade assembly (216) includes a blade (2161) and a support rod (2162). The head end of the blade (2161) is hinged to the limiting part (2151), the tail end of the blade (2161) is hinged to the head end of the support rod (2162), and the tail end of the support rod (2162) is hinged to the second tube body (2122).

4. The drilling tool for partial protection of high-level directional holes in the roof of a coal mine as described in claim 1, characterized in that, The sleeve shoe (7) includes a hollow sleeve shoe body, which includes a sleeve shoe connector (71) and a shoulder body (72) connected from back to front. Multiple cutting teeth (73) are arranged circumferentially on the front end face of the shoulder body (72). Multiple radial fan-shaped bosses (721) are evenly distributed on the inner circumference of the shoulder body (72), and a first slag return groove (723) is formed between adjacent radial fan-shaped bosses (721).

5. The drilling tool for partial protection of high-level directional holes in the roof of a coal mine as described in claim 4, characterized in that, The radial fan-shaped boss (721) is further provided with a guide platform (722) at the end away from the cutting tooth (73). The small diameter end of the guide platform (722) is connected to the radial fan-shaped boss (721), and the large diameter end of the guide platform (722) is connected to the sleeve shoe connector (71).

6. The drilling tool for partial protection of high-level directional holes in the roof of a coal mine as described in claim 4, characterized in that, The pusher (6) includes a hollow pusher body (61) and a pusher connector (62) disposed at the rear end of the hollow pusher body (61). Multiple radial pusher splines (611) are evenly distributed on the outer circumferential surface of the pusher body (61). The radial pusher splines (611) can be inserted and engaged with the first return slag groove (723). The pusher connector (62) is threadedly connected to the straight screw motor (5).

7. The drilling tool for partial protection of high-level directional holes in the roof of a coal mine as described in claim 6, characterized in that, The number of the first slag return grooves (723) is three, the number of the radial push splines (611) is six, and the angle of the central angle corresponding to the first slag return grooves (723) is greater than the angle of the central angle corresponding to the radial push splines (611). The outer diameter of the radial push spline (611) is smaller than the inner diameter of the hollow sleeve (1) and larger than the inner diameter of the shoulder body (72).

8. The drilling tool for partial protection of high-level directional holes in the roof of a coal mine as described in claim 1, characterized in that, The centralizer (3) includes a centralizer female connector (31), a centralizer body (32), and a centralizer male connector (33) that are integrally connected from back to front. The centralizer male connector (33) is threadedly connected to the impactor female connector located at the rear end of the hydraulic impactor (4). The centralizer body (32) has multiple spiral centralizer ridges (321) on its outer wall, and a spiral channel is formed between adjacent centralizer ridges (321).

9. The drilling tool for partial protection of high-level directional holes in the roof of a coal mine as described in claim 1, characterized in that, A transition joint is provided between the straight screw motor (5) and the hydraulic impactor (4), and the outer walls of both ends of the transition joint are respectively provided with connecting threads for connecting the straight screw motor (5) and the hydraulic impactor (4).

10. A construction method for a drilling tool for partial protection of high-level directional holes in the roof of a coal mine, characterized in that, The construction method is achieved using the local protection drilling tool for high-level directional holes in the underground roof of coal mines as described in any one of claims 1 to 9, and includes the following steps: Step 1: Lower the assembled partial borehole protection tool into the borehole; Step 2: Start the mud pump and pump high-pressure flushing medium into the local borehole protection tool through the drill pipe. The high-pressure flushing medium propels the local borehole protection tool forward in the preset drilling direction. During drilling, the high-pressure flushing medium flowing through the inner tube of the borehole cleaner flows out through the head of the inner tube and pushes the piston body to move axially. This pushes the borehole cleaning blade assembly to extend out of the first tube through the rectangular through hole, thus achieving mechanical borehole cleaning. Part of the high-pressure flushing medium flowing through the inner tube of the borehole cleaner enters the rectangular through hole through the gap between the piston body and the inner tube and is ejected, while part is ejected through the reverse jet hole, thus achieving hydraulic flushing. Step 3: After completing the drilling operation, turn off the mud pump. The piston body will be reset under the action of the return spring. The hole sweeping blade assembly will be retracted into the rectangular through hole. After the piston body is reset, the reverse jet hole will be blocked, and the local hole protection drill bit will be retrieved.

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