Coal mine underground directional long borehole middle part driving type casing running system and method

Abstract

The present application belongs to the technical field of downhole directional drilling casing running, and discloses a coal mine downhole directional long borehole middle driving type casing running system and method, which comprises a pipe string and a drilling tool, the pipe string comprises multiple standard pipe joints, a guide head and at least one driving pipe joint, the driving pipe joint is internally provided with an assembly ring, a rotating ring, a bayonet and a clamping groove, the drilling tool has a torque transmission head inserted into the bayonet at the tail end, and the torque transmission head is provided with a clamping mechanism; a one-way transmission assembly is arranged between the rotating ring and the driving pipe joint, a drill rod channel is arranged in the drilling tool, and a connecting column is internally provided with a communication port, a pressure cavity and a flushing flow channel; the driving pipe joint can further be provided with a magnetic actuator and an impact generation assembly. When the system is used, the drilling tool is clamped with the driving pipe joint, the pushing force and the rotating torque are introduced into the corresponding position in the hole to be applied, and the drilling tool can be idled and retreated under the reverse working condition, the clamping area can be flushed, and the axial pulsation can be formed at the blocked position, so that the continuity, stability and adaptability of the long borehole casing running are improved.

Description

Technical Field

[0001] This invention belongs to the field of underground directional drilling casing installation technology, specifically a mid-drive casing installation system and method for underground directional long boreholes in coal mines. Background Technology

[0002] With the development of directional drilling technology in coal mines, the construction depth and horizontal extension distance of long directional boreholes are constantly increasing. In gas extraction, water exploration and drainage, borehole protection, and subsequent segmented operations, it is usually necessary to run casing or screen pipes along the borehole to maintain the stability of the borehole section and ensure the smooth progress of subsequent procedures. In current construction practices, casing is mostly run by gradually pushing it into the borehole from the wellhead end, with auxiliary lowering sometimes assisted by drill string rotation or flushing fluid circulation.

[0003] However, in long directional boreholes in coal mines, especially in long horizontal sections, sections with varying curvature, or sections with uneven borehole diameters, the increased contact length between the casing string and the borehole wall allows coal dust, rock cuttings, and mud deposits to easily create additional resistance. When the axial thrust and rotational torque applied at the wellhead are transmitted along the entire casing string, the efficiency of the force transmitted to the front of the borehole tends to decrease, while the rear connection position continuously bears a large axial load and alternating torque. At the same time, during rotary-assisted lowering, directional adjustment, and repeated engagement and disengagement processes, if impurities adhere to the engagement area, loosening of the connection, disengagement, difficulty in unclamping, and decreased stability of re-engagement can easily occur, thus affecting the continuity and stability of long borehole casing lowering operations. Summary of the Invention

[0004] The purpose of this invention is to provide a mid-drive casing lowering system and method for directional long boreholes in coal mines, in order to solve the problems mentioned in the background art.

[0005] To achieve the above objectives, the present invention provides the following technical solution: a mid-drive casing lowering system and method for directional long boreholes in coal mines, comprising:

[0006] A tubing string, comprising multiple standard tubing sections connected in series along its axial direction, wherein a guide head is provided at the wellhead end of the tubing string and at least one drive tubing section is provided in the middle of the tubing string;

[0007] Drilling tools used to deliver tools into boreholes and transmit axial force and rotational torque;

[0008] The drive pipe section includes a pipe body and an assembly ring fixed to the inner wall of the pipe body. The assembly ring is rotatably provided with a rotating ring. The rotating ring has a slot extending along its axial direction and a groove on the inner wall of the slot.

[0009] A one-way transmission assembly is provided between the rotating ring and the drive tube section. When the rotating ring rotates relative to the drive tube section in a first rotation direction, the one-way transmission assembly engages to drive the drive tube section to rotate synchronously. When the rotating ring rotates relative to the drive tube section in a second rotation direction opposite to the first rotation direction, the one-way transmission assembly disengages, and the rotating ring idles.

[0010] The end of the drill bit is provided with a torque transmission head, which can be delivered by the drill bit and inserted into the bayonet of the rotating ring. The torque transmission head is provided with a locking mechanism, which engages with the slot in the bayonet when it is activated, so as to transmit the rotational torque of the drill bit to the rotating ring. After the torque transmission head is inserted into place, it transmits axial thrust to the drive pipe section.

[0011] Preferably, the outer periphery of the rotating ring is provided with a first rotating engagement portion, and is rotatably mounted on the assembly ring through the first rotating engagement portion.

[0012] Preferably, the unidirectional transmission assembly includes a movable block movably disposed on the outer wall of the rotating ring and a first elastic element acting on the movable block to give it an outward extension tendency; the assembly ring is provided with a fixedly disposed limiting protrusion; the movable block has a first contour surface and a second contour surface, and the limiting protrusion has a third contour surface adapted to the first contour surface and a fourth contour surface adapted to the second contour surface; when the rotating ring rotates along a first rotation direction, the first contour surface and the third contour surface engage to transmit torque; when the rotating ring rotates along a second rotation direction, the second contour surface and the fourth contour surface interact, causing the movable block to retract against the force of the first elastic element to avoid the limiting protrusion.

[0013] Preferably, the first contour surface of the movable block is a vertical plane, and the second contour surface is an arc surface; the third contour surface of the limiting protrusion is a vertical plane, and the fourth contour surface is an arc surface.

[0014] Preferably, the torque transmission head includes a connecting column, a communication port on the front of the connecting column, and a pressure chamber on the outer wall of the connecting column, wherein the pressure chamber is connected to the communication port;

[0015] The locking mechanism includes a movable locking block movably disposed inside the pressure chamber, a second elastic element acting on the movable locking block to give it a tendency to retract, and a dynamic sealing ring fixedly sleeved on the outer periphery of the rear end of the movable locking block.

[0016] When the fluid pressure in the pressure chamber reaches a first preset value, the movable block extends outward against the force of the second elastic element and engages with the slot in the bayonet; when the pressure chamber is depressurized, the movable block retracts under the action of the second elastic element.

[0017] Preferably, the drilling tool includes a drill rod body and a drill rod channel disposed inside the drill rod body, the drill rod body being detachably inserted into the communication port, and the drill rod channel communicating with the communication port.

[0018] Preferably, the connecting column is further provided with a flushing channel, the inlet of the flushing channel is connected to the connecting port, and the outlet of the flushing channel faces the engagement area of ​​the movable block and the slot; the flushing channel is provided with a pressure control valve, and the opening pressure of the pressure control valve is higher than a first preset value.

[0019] Preferably, the movable card block is provided with a flow guide groove, which cooperates with the outlet of the flushing channel; the rotating ring is provided with a trumpet-shaped guide cover at the end facing the wellhead, and the large end of the guide cover faces the wellhead.

[0020] Preferably, a magnetic drive element is provided on the outer periphery of the rotating ring; a magnetic actuator and an impact generating assembly are also provided inside the drive tube section. The magnetic actuator includes a hydraulic chamber opened inside the assembly ring, an assembly piece fixed to the inner wall of the assembly ring, a magnetic piston movably sleeved inside the assembly piece, and a third elastic element fixedly connected to the magnetic piston. The other end of the third elastic element is fixed in the hydraulic chamber. The magnetic piston moves in response to the magnetic drive element. The impact generating assembly includes a fixed sleeve fixed to the end of the assembly ring and communicating with the hydraulic chamber, a piston rod movably sleeved inside the fixed sleeve, a fourth elastic element sleeved on the piston rod, and a fixed block fixed to the inner wall of the tube. The piston rod impacts the fixed block axially under the drive of fluid pressure. When the rotating ring is idling, the rotating magnetic drive element periodically drives the magnetic piston, transmitting the motion to the impact generating assembly through the compression of the hydraulic chamber, and driving the piston rod to generate an axial impact.

[0021] A method for running a driven casing in the middle of a long directional borehole in a coal mine includes the following steps:

[0022] Step 1: Connect the pipe string containing at least one drive pipe section and feed it into the borehole;

[0023] Step 2: The torque transmission head is delivered to the drive pipe section through the drill bit, and the torque transmission head is inserted into the bayonet of the rotating ring;

[0024] Step 3: Inject fluid into the drill bit to make the fluid pressure reach the first preset value, drive the snapping mechanism to act, and make the torque transmission head engage with the rotating ring.

[0025] Step 4: By applying axial thrust and rotational torque through the drill bit, the rotating ring is driven to rotate in the first rotation direction. The one-way transmission assembly drives the drive pipe section and the pipe string to rotate synchronously, thereby realizing the push-rotation-down insertion.

[0026] Step 5: When it is necessary to adjust the direction or prevent the threads from loosening, control the drill bit to apply a torque in a second rotation direction opposite to the first rotation direction. At this time, the rotating ring will rotate freely and will not drive the pipe string.

[0027] Step 6: After the lowering operation is completed, reduce the fluid pressure in the clamping mechanism to allow the clamping mechanism to retract and disengage, and withdraw the drill bit and torque transmission head; wherein, before disengagement, the fluid pressure in the drill bit can be increased to a second preset value higher than the first preset value, so that the high-pressure fluid flushes the clamping area between the torque transmission head and the rotating ring.

[0028] The beneficial effects of this invention are as follows:

[0029] 1. This invention provides a drive pipe section in the middle of the casing string that can cooperate with the drill string. After the drill string advances to the target hole section inside the casing string, the torque transmission head establishes a torque transmission and axial pressure relationship with the drive pipe section. This introduces the jacking force and rotational force required for casing installation to the corresponding position inside the hole. As a result, during the installation of long directional drilling, especially long horizontal sections, the rotational driving force no longer relies solely on the wellhead end to be transmitted step by step along the entire string. The front hole section receives a more direct driving effect, and the alternating torque that the multiple threaded connections at the rear are subjected to for a long time is correspondingly reduced. The casing installation process is closer to the actual force requirements.

[0030] 2. This invention, by setting a rotating ring inside the drive pipe section and setting a one-way transmission structure consisting of a movable block, a first elastic element, and a limiting protrusion between the rotating ring and the drive pipe section, enables the rotating ring to stably drive the drive pipe section to rotate synchronously when moving in the first rotation direction, while only the rotating ring rotates relative to each other when moving in the opposite direction. When rotation is needed to assist in lowering, the driving action can be transmitted to the corresponding pipe section. When reverse adjustment is needed or to avoid the connection from continuing to bear reverse torque, the drive pipe section does not reverse accordingly, and the connection of the entire series of sleeves is not prone to loosening due to frequent reverse torsion, so that pushing, rotation, and direction adjustment can be continuously switched in the same structure.

[0031] 3. This invention features a locking mechanism on the torque transmission head, consisting of a pressure chamber, a movable locking block, a second elastic element, and a sealing structure. A graded fluid supply passage and flushing channel are also provided within the connecting column. This allows the torque transmission head to engage under initial pressure after insertion, followed by fluid flow under higher pressure to the engagement area between the movable locking block and the slot. In situations with high levels of coal dust, rock cuttings, and mud particles in the borehole, the torque transmission head can first establish a stable torque connection before flushing and cleaning the engagement area. When the operation is completed or needs to be withdrawn, the movable locking block retracts more smoothly, and the stability of repeated engagement and disengagement is higher, facilitating the sequential deployment of the same drill bit with different drive sections for segmented drilling.

[0032] 4. This invention further incorporates an auxiliary mechanism within the drive pipe section, consisting of a magnetic drive component, a magnetic actuator, and an impact generating assembly. This allows the idling process of the rotating ring to be converted into axial pulsating motion of the drive pipe section. When the casing encounters significant friction, step obstruction, or deposits in a local section, making it unsuitable to continue applying greater reverse torque to the entire casing string, the periodic axial action generated in the idling state can create continuous disturbance at the obstructed location, facilitating the casing's continued forward movement. This allows rotation assistance, torque avoidance, and local unblocking to be seamlessly integrated during the same operation, thereby enhancing the continuity and adaptability of directional long borehole casing installation in coal mines. Attached Figure Description

[0033] Figure 1 This is a schematic diagram of the structure of the present invention;

[0034] Figure 2 This is a cross-sectional view of the present invention;

[0035] Figure 3 This is a cross-sectional view of the drive tube section and torque transmission head of the present invention;

[0036] Figure 4 This is an exploded view of the rotating ring and unidirectional transmission assembly of the present invention;

[0037] Figure 5 This is an exploded view of the tube body and assembly ring of the present invention;

[0038] Figure 6 This is a cross-sectional view of the unidirectional transmission assembly and the locking mechanism of the present invention;

[0039] Figure 7 This is a schematic diagram of the torque transmission head of the present invention;

[0040] Figure 8 This is a cross-sectional view of the torque transmission head and snap-fit ​​mechanism of the present invention;

[0041] Figure 9 This is a schematic diagram of the rotating ring of the present invention;

[0042] Figure 10 This is a cross-sectional view of the assembly ring and magnetic actuator of the present invention;

[0043] Figure 11 for Figure 10 A magnified schematic diagram of the structure at point A in the middle.

[0044] In the diagram: 1. Standard pipe section; 2. Guide head; 3. Drive pipe section; 301. Pipe body; 302. Assembly ring; 303. Rotating ring; 304. Bayonet; 305. Slot; 4. Drill tool; 401. Drill pipe body; 402. Drill pipe channel; 5. One-way transmission assembly; 501. Movable block; 502. First elastic element; 503. Limiting protrusion; 6. Torque transmission head; 601. Connecting column; 602. Connecting port; 603. Pressure chamber; 7. Clamping mechanism; 701. Movable 702. Second elastic element; 703. Dynamic sealing ring; 8. First rotating mating part; 9. Flushing flow channel; 10. Pressure control valve; 11. Guide groove; 12. Guide cover; 13. Magnetic drive element; 14. Magnetic actuator; 1401. Magnetic piston; 1402. Assembly kit; 1403. Hydraulic chamber; 1404. Third elastic element; 15. Impact generating assembly; 1501. Piston rod; 1502. Fixing sleeve; 1503. Fixing block; 1504. Fourth elastic element. Detailed Implementation

[0045] like Figures 1 to 11 As shown, the mid-drive casing lowering system for directional long boreholes in coal mines includes a pipe string and a drill string 4. The pipe string is formed by connecting multiple standard pipe sections 1 sequentially along the axial direction, with a guide head 2 connected at the entry end and at least one drive pipe section 3 connected in series in the middle. The drive pipe section 3 includes a pipe body 301 and an assembly ring 302 fixed to the inner wall of the pipe body 301. A rotating ring 303 that can rotate relative to the inner side of the assembly ring 302 is provided. A bayonet 304 is formed axially at the center of the rotating ring 303, and a slot 305 is formed on the inner wall of the bayonet 304 for the bayonet mechanism 7 to extend into. The drive pipe section 3 is positioned in the middle of the pipe string or near the target position of the long horizontal section. After the drill string 4 enters the pipe string, it can directly engage with the rotating ring 303 at the corresponding position, so that the rotational driving force and axial thrust are applied in the corresponding section inside the hole, instead of the entire string at the wellhead end bearing the rotation. With this arrangement, when the front part of the pipe string continues to be run, the rotation point can change with the change of the drive position, and the reverse loosening torque at each threaded connection of the pipe string is relatively reduced, making it closer to the actual downhole stress state when running long distances.

[0046] The two ends of the pipe body 301 form connecting parts corresponding to the standard pipe section 1. The outer diameter of the pipe body 301 is continuous with the outer diameter of the adjacent standard pipe section 1 to reduce interference with the borehole wall during the lowering process. After the assembly ring 302 is fixed to the inner wall of the pipe body 301, it remains coaxial with the pipe body 301. The assembly ring 302 and the pipe body 301 can be fixed by one or more combinations of interference fit, limiting shoulder fit, and anti-reverse fit. The rotating ring 303 is installed in the assembly ring 302 through the first rotating fit part 8. The first rotating fit part 8 preferably adopts any one of the following: circumferential flange and annular groove fit, step and retaining ring fit, or sleeve-type sliding fit, so that the rotating ring 303 can rotate relative to the assembly ring 302 in the circumferential direction and is subject to bidirectional limiting in the axial direction. A rotation gap is left between the rotating ring 303 and the assembly ring 302. The rotation gap is determined to allow smooth rotation in the downhole mud, coal powder, or rock powder environment. If necessary, a wear-resistant layer or liquid storage micro-groove is formed on the mating surface. A guide cover 12 is installed at the end of the rotating ring 303 facing the wellhead. The guide cover 12 has a trumpet-shaped structure, with its larger end facing the wellhead. When the drill string 4 enters, it first contacts the guide cover 12 and then converges towards the center of the chuck 304. The chuck 304 is preferably square, quasi-square, or other irregularly shaped through-hole structure with the ability to prevent relative slippage. The chuck grooves 305 are arranged at intervals along the circumferential direction of the inner wall of the chuck 304.

[0047] A one-way transmission assembly 5 is provided between the rotating ring 303 and the drive tube section 3. The one-way transmission assembly 5 includes a movable block 501, a first elastic element 502, and a limiting protrusion 503. The movable block 501 is inserted into a guide cavity formed on the outer periphery of the rotating ring 303. The guide cavity limits the movable block 501 to reciprocating only radially. The first elastic element 502 is located inside the movable block 501 and applies a continuous outward preload to the movable block 501. The limiting protrusion 503 is fixed to the inner wall of the assembly ring 302 or at a corresponding position of the first rotating mating part 8. The outer end of the movable block 501 forms a first contour surface and a second contour surface. The limiting protrusion 503 forms a corresponding third contour surface and a fourth contour surface. The first contour surface and the third contour surface are preferably vertical planes that abut each other, and the second contour surface and the fourth contour surface are preferably arc surfaces that guide each other. When the rotating ring 303 rotates in the first rotation direction, the movable block 501 remains extended under the action of the first elastic element 502. The first contour surface and the third contour surface are in contact to transmit force. The circumferential force is transmitted to the assembly ring 302 and the tube body 301 through the limiting protrusion 503, and the driving tube section 3 rotates synchronously. When the rotating ring 303 rotates in the second rotation direction, the second contour surface and the fourth contour surface press against each other. Under the guidance, the movable block 501 retracts inward and compresses the first elastic element 502. After the movable block 501 retracts into the guide cavity, it avoids the limiting protrusion 503. The rotating ring 303 continues to rotate without driving the driving tube section 3 to rotate. The outermost edge of the retracted movable block 501 is located inside the rotation trajectory of the limiting protrusion 503. The retraction stroke of the movable block 501 is greater than the interference amount corresponding to the limiting protrusion 503 to ensure the continuity of the reverse idling process. The movable block 501 and the limiting protrusion 503 can be evenly arranged in two, three, or four sets along the circumference to make the rotating ring 303 more evenly stressed. This structure adopts a combination of planar torsion bearing and circular arc relief, which makes the force surface clear when transmitting torsion in the forward direction and the relief path stable when rotating in the reverse direction, making it suitable for downhole working conditions with repeated switching.

[0048] The drill string 4 adopts a hollow drill pipe structure, forming a drill pipe channel 402 inside, and is connected to a torque transmission head 6 at the end. The torque transmission head 6 includes a connecting post 601, the shape of which matches the bayonet 304, and a chamfer at the front end. After being inserted into place, the front bearing surface contacts the rotating ring 303 or the internal bearing part of the drive pipe section 3. The axial thrust applied by the drill string 4 is transmitted to the pipe body 301 through the connecting post 601, the rotating ring 303, and the assembly ring 302. A connecting port 602 is formed inside the connecting post 601. The connecting port 602 extends axially towards the wellhead side to form a plug section for the drill pipe body 401 to be inserted. After the front end of the drill pipe body 401 is inserted into the connecting port 602, it is coaxially arranged with the connecting post 601, and the drill pipe channel 402 is connected to the connecting port 602. To ensure the detachable and fixed relationship between the drill pipe body 401 and the connecting post 601, aligning pin holes are provided on the corresponding sections of the front outer wall of the drill pipe body 401 and the connecting port 602. After the drill pipe body 401 is inserted into place, it is locked and limited by the transversely inserted pin. The pin provides axial anti-disengagement limit for the drill pipe body 401 and ensures that the rotational torque of the drill pipe body 401 can be stably transmitted to the connecting post 601. During the insertion of the connecting post 601 into the bayonet 304, the movable locking block 701 remains in the retracted state, allowing the outer contour of the connecting post 601 to pass smoothly through the inner cavity of the bayonet 304. After it is in place, hydraulic locking is performed.

[0049] A distribution ring is fitted around the outer periphery of the end of the drill pipe body 401 furthest from the connecting post 601. The drill pipe body 401 and the distribution ring form a circumferential relative rotational fit, with a dynamic sealing structure between them. External pressurized fluid first enters the distribution ring, then enters the drill pipe channel 402 through radial guide holes on the outer wall of the drill pipe body 401, and then enters the connecting port 602 along the drill pipe channel 402. During fluid supply, the distribution ring remains relatively stationary, while the drill pipe body 401 rotates relative to it within the distribution ring. The dynamic sealing structure seals the annular flow channel between the distribution ring and the drill pipe body 401, thus ensuring a stable supply of pressurized fluid to the drill pipe channel 402 even as the drill string 4 continues to rotate. This ensures that the drill string 4 will not collide with the front of the chuck 304 due to the exposed movable chuck 701 during long-distance transport, and also facilitates repeated searching and engagement of drive pipe sections 3 at different positions within the hole, while simultaneously accommodating the rotational drive and hydraulic supply of the drill string 4.

[0050] A locking mechanism 7 is mounted on the torque transmission head 6. A movable locking block 701 and a second elastic element 702 are installed inside the pressure chamber 603. A dynamic sealing ring 703 is provided on the outer periphery of the rear end of the movable locking block 701, forming a sliding seal with the inner wall of the pressure chamber 603. A locking part and a guiding part are formed at the outer end of the movable locking block 701. The locking part engages with the side wall of the slot 305, and the guiding part guides the movable locking block 701 to remain retracted when it contacts the edge of the slot 304 during the insertion of the connecting post 601. The second elastic element 702 is preferably a compression spring, installed inside the pressure chamber 603, continuously applying an inward restoring force to the movable locking block 701. After pressure medium is input into the drill string 4, the pressure medium enters the connecting port 602 along the drill pipe channel 402, and then enters the pressure chamber 603. Under hydraulic pressure, the movable locking block 701 moves radially outward and enters the slot 305, completing the locking connection between the torque transmission head 6 and the rotating ring 303. After the pressure supply is released, the second elastic element 702 pushes the movable locking block 701 to retract, and the liquid in the pressure chamber 603 can flow back to the drill pipe channel 402 through the connecting port 602. To make the retraction process smoother, a low-pressure return fluid branch connected to the pressure chamber 603 can also be formed in the connecting column 601. A one-way return fluid element is set in the return fluid branch so that when the movable locking block 701 retracts, the liquid in the chamber is preferentially discharged to the low-pressure side. After this treatment, the extension and retraction of the movable locking block 701 form a complete reciprocating path, and the downhole card ejection does not rely on external mechanical manipulation.

[0051] A first pressure control valve is installed at the connecting port 602. The opening pressure of the first pressure control valve corresponds to the first preset value required for the movable locking block 701 to extend outward. A flushing channel 9 is also formed inside the connecting column 601. The inlet of the flushing channel 9 is connected to the high-pressure area of ​​the connecting port 602 or the drill pipe channel 402, and the outlet faces the engagement area of ​​the movable locking block 701 and the slot 305. A pressure control valve 10 is installed on the flushing channel 9. The opening pressure of the pressure control valve 10 is higher than the opening pressure of the first pressure control valve. A guide groove 11 is formed on the outer surface of the movable locking block 701. The guide groove 11 is composed of an outer transverse groove and two side lateral grooves connected together. When the liquid pressure is near the first preset value, the liquid preferentially enters the pressure chamber 603 to push the movable locking block 701 outward. After the movable locking block 701 has extended into the locking groove 305 and completed the locking, the liquid pressure continues to increase, the pressure control valve 10 opens, and the liquid is then sprayed through the flushing channel 9 towards the joint area between the movable locking block 701 and the locking groove 305, and enters the interior of the locking groove 305 along the guide channel 11, carrying away coal dust, rock fragments, or mud deposits from the joint surface. The flushing and locking are controlled sequentially and in stages, which not only avoids premature leakage of flushing fluid before the connecting column 601 is in place, but also facilitates cleaning of the locking area before subsequent pressure relief and retraction.

[0052] In a preferred embodiment, a magnetic drive element 13 is disposed on the outer periphery of the rotating ring 303, and a magnetic actuator 14 and an impact generating assembly 15 are disposed inside the drive tube section 3. The magnetic actuator 14 includes a mounting device 1402, a magnetic piston 1401, a hydraulic chamber 1403, and a third elastic element 1404. The mounting device 1402 is fixed inside the mounting ring 302, the magnetic piston 1401 is inserted into the mounting device 1402 and forms a sliding seal with the mounting device 1402, and the third elastic element 1404 is connected between the rear end of the magnetic piston 1401 and the end of the hydraulic chamber 1403. The impact generating assembly 15 includes a fixed sleeve 1502, a piston rod 1501, a fourth elastic element 1504, and a fixed block 1503. The fixed sleeve 1502 is fixedly connected to the assembly ring 302 and communicates with the hydraulic chamber 1403 through an internal hydraulic transmission channel. The piston rod 1501 is installed in the fixed sleeve 1502 and slides axially. The fixed block 1503 is fixed on the inner wall of the tube body 301 and is arranged opposite to the impact end of the piston rod 1501.

[0053] The fourth elastic element 1504 is sleeved on the outer periphery of the piston rod 1501 and located inside the fixed sleeve 1502. One end of the fourth elastic element 1504 abuts against the limiting part inside the fixed sleeve 1502, and the other end abuts against the pressure-bearing shoulder or limiting part on the piston rod 1501. When the piston rod 1501 moves in the direction close to the fixed block 1503 under hydraulic pressure, the fourth elastic element 1504 is compressed. When the pressure in the hydraulic chamber 1403 drops, the fourth elastic element 1504 releases its elastic potential energy and pushes the piston rod 1501 back in the direction away from the fixed block 1503, so that the piston rod 1501 returns to its initial ready-to-strike position before the next pressure push. After the fourth elastic element 1504 cooperates with the piston rod 1501, on the one hand, it enables the piston rod 1501 to return in time after each impact, avoiding the piston rod 1501 from continuously pressing against the fixed block 1503 and affecting subsequent pulsating actions. On the other hand, it enables the piston rod 1501 to maintain an axial elastic support state within the fixed sleeve 1502, so that the intermittent hydraulic thrust formed when the rotating ring 303 rotates idly can be converted into repeated reciprocating impact actions.

[0054] The hydraulic chamber 1403, the hydraulic transmission channel, and the inner cavity of the fixed sleeve 1502 together form a closed hydraulic circuit, which is pre-charged with pressure medium. When the rotating ring 303 rotates in reverse, the magnetic drive component 13 periodically passes the corresponding position of the magnetic piston 1401. The magnetic piston 1401 moves back and forth under the action of the magnetic field, and the pressure in the hydraulic chamber 1403 changes accordingly. The pressure medium in the circuit pushes the piston rod 1501 forward and impacts the fixed block 1503, and then retracts under the action of the return hydraulic pressure and the reset structure. This structure is arranged to operate under idling conditions. When the rotating ring 303 rotates in reverse, it will not continue to add reverse torque to the entire threaded connection, but will convert the idling process into the axial pulsating action of the driving pipe section 3.

[0055] The pipe body 301, assembly ring 302, rotating ring 303, connecting column 601, movable block 501, and movable locking block 701 are preferably made of medium-to-high strength alloy steel, with preferred materials including 42CrMo, 40Cr, 35CrMo, or other steels with high torsional and impact resistance. The contact surfaces of the movable block 501 and the limiting protrusion 503, the locking surfaces of the movable locking block 701 and the locking groove 305, and the pressure-bearing surfaces at the front end of the connecting column 601 are preferably treated with tempering, surface hardening, nitriding, carbonitriding, or welding a wear-resistant layer. The dynamic sealing ring 703 is preferably made of polyurethane, nitrile rubber, fluororubber, or polytetrafluoroethylene composite sealing material. The pressure medium in the pressure chamber 603 and the hydraulic chamber 1403 can be mineral hydraulic oil, water-based pressure fluid, or other pressure media permitted for downhole use. The fixed connection between the assembly ring 302 and the pipe body 301, the assembly sleeve 1402 and the assembly ring 302, and the fixed sleeve 1502 and the assembly ring 302 preferably adopts an interference fit and is supplemented with a backstop structure. The relative sliding parts of the moving parts retain a working clearance so that the pressure medium can establish a stable pressure, while taking into account the reliability of the operation in the downhole particle environment.

[0056] The working principle is as follows.

[0057] First, the tubing string is assembled according to the borehole length and target insertion depth. Multiple standard tubing sections 1 are connected sequentially. The guide head 2 is located at the entry point, and the drive tubing section 3 is positioned where local rotation is required. After the tubing string is inserted into the borehole, the drill string 4 enters the tubing string from the wellhead. The torque transmission head 6 is located at the front end of the drill string 4 and moves along the center of the tubing string. When the connecting column 601 approaches the target drive tubing section 3, it first enters the guide cover 12, and then, guided by the guide cover 12, aligns with the center of the bayonet 304 and continues to be inserted forward into the bayonet 304. At this time, the movable locking block 701 remains retracted, and the outer contour of the connecting column 601 does not exceed the allowable range of the bayonet 304.

[0058] After the connecting post 601 is inserted into place, the external pressure fluid first enters the distribution ring sleeved on the outer periphery of the drill pipe body 401, then enters the drill pipe channel 402 through the radial guide hole on the outer wall of the drill pipe body 401, and subsequently enters the pressure chamber 603 along the connecting port 602. During the rotation of the drill pipe body 401, it rotates relative to the distribution ring, and the dynamic sealing structure between the distribution ring and the drill pipe body 401 maintains the sealing state of the fluid supply passage. After the pressure reaches the first preset value, the movable locking block 701 moves radially outward and enters the locking groove 305, and the torque transmission head 6 and the rotating ring 303 enter the locked state. Subsequently, the drill bit 4 applies axial thrust and first rotational torque, the connecting column 601 drives the rotating ring 303 to rotate, the movable block 501 remains extended under the action of the first elastic element 502, the first contour surface and the third contour surface fit together to transmit force, the circumferential force of the rotating ring 303 is transmitted to the assembly ring 302 and the pipe body 301 through the limiting protrusion 503, the driving pipe section 3 drives the corresponding section of the pipe string to rotate synchronously, at the same time the axial thrust is transmitted to the driving pipe section 3 through the connecting column 601 and the pressure bearing part, and the pipe string continues to go down along the borehole.

[0059] When it is necessary to adjust the direction or avoid the reverse torque transmission to the entire pipe string, the drill string 4 switches to the second rotation direction. At this time, the second contour surface of the outer end of the movable block 501 contacts the fourth contour surface of the limiting protrusion 503, the movable block 501 retracts radially into the guide cavity, the rotating ring 303 rotates idling relative to the assembly ring 302, and the drive pipe section 3 does not rotate in the reverse direction. When the rotating ring 303 continues to rotate idling, if the drive pipe section 3 is equipped with a magnetic drive component 13, a magnetic actuator 14 and an impact generating component 15, the magnetic drive component 13 moves with the rotating ring 303 and periodically drives the magnetic piston 1401 to reciprocate. The pressure medium in the hydraulic chamber 1403 pushes the piston rod 1501 forward through the hydraulic transmission channel. The piston rod 1501 contacts the fixed block 1503 and then retracts. This action is repeated.

[0060] When impurities adhere between the movable locking block 701 and the slot 305, the fluid pressure inside the drill string 4 is increased, the pressure control valve 10 opens, and the pressure medium is ejected from the engagement area between the movable locking block 701 and the slot 305 through the flushing channel 9, and enters the slot 305 along the guide groove 11. When it is necessary to withdraw the drill string 4, the pressure supply is first released or reduced. The movable locking block 701 retracts under the push of the second elastic element 702, and the fluid in the pressure chamber 603 flows back in the reverse direction through the connecting port 602 or is discharged to the low-pressure side through the return fluid branch. The movable locking block 701 exits the slot 305, the torque transmission head 6 and the rotating ring 303 are unlocked, and the drill string 4 is then withdrawn from the pipe string. When multiple drive pipe sections 3 are arranged in the pipe string, the drill string 4 can continue to move to the next drive pipe section 3, repeating the insertion, locking, pushing, rotating, and unlocking actions until the entire pipe string is lowered.

Claims

1. A mid-drive casing lowering system for directional long boreholes in coal mines, characterized in that: include: The tubing string includes multiple standard tubing sections (1) connected in series along its axial direction, a guide head (2) is provided at the wellhead end of the tubing string, and at least one drive tubing section (3) is provided in the middle of the tubing string. Drilling tools (4) are used to deliver tools into the borehole and transmit axial force and rotational torque. The drive pipe section (3) includes a pipe body (301) and an assembly ring (302) fixedly disposed on the inner wall of the pipe body (301). The assembly ring (302) is rotatably provided with a rotating ring (303). The rotating ring (303) is provided with a slot (304) extending along its axial direction. The inner wall of the slot (304) is provided with a groove (305). A one-way transmission assembly (5) is provided between the rotating ring (303) and the drive tube section (3). When the rotating ring (303) rotates relative to the drive tube section (3) in a first rotation direction, the one-way transmission assembly (5) engages to drive the drive tube section (3) to rotate synchronously. When the rotating ring (303) rotates relative to the drive tube section (3) in a second rotation direction opposite to the first rotation direction, the one-way transmission assembly (5) disengages, and the rotating ring (303) idles. The end of the drill bit (4) is provided with a torque transmission head (6). The torque transmission head (6) can be delivered by the drill bit (4) and inserted into the bayonet (304) of the rotating ring (303). The torque transmission head (6) is provided with a snap-fit ​​mechanism (7). When the snap-fit ​​mechanism (7) is activated, it engages with the slot (305) in the bayonet (304) to transmit the rotational torque of the drill bit (4) to the rotating ring (303). After the torque transmission head (6) is inserted into place, it transmits axial thrust to the drive pipe section (3).

2. The mid-drive casing lowering system for directional long boreholes in coal mines according to claim 1, characterized in that, The outer periphery of the rotating ring (303) is provided with a first rotating fitting part (8), and is rotatably mounted on the assembly ring (302) through the first rotating fitting part (8).

3. The mid-drive casing lowering system for directional long boreholes in coal mines according to claim 2, characterized in that, The one-way transmission assembly (5) includes a movable block (501) movably disposed on the outer wall of the rotating ring (303) and a first elastic element (502) acting on the movable block (501) to give it an outward extension tendency; the assembly ring (302) is provided with a fixedly disposed limiting protrusion (503); the movable block (501) has a first contour surface and a second contour surface, and the limiting protrusion (503) has a third contour surface adapted to the first contour surface and a fourth contour surface adapted to the second contour surface; when the rotating ring (303) rotates along a first rotation direction, the first contour surface and the third contour surface mesh to transmit torque; when the rotating ring (303) rotates along a second rotation direction, the second contour surface and the fourth contour surface interact to cause the movable block (501) to retract against the force of the first elastic element (502) to avoid the limiting protrusion (503).

4. The mid-drive casing lowering system for directional long boreholes in coal mines according to claim 3, characterized in that, The first contour surface of the movable block (501) is a vertical plane, and the second contour surface is an arc surface; the third contour surface of the limiting protrusion (503) is a vertical plane, and the fourth contour surface is an arc surface.

5. The mid-drive casing lowering system for directional long boreholes in coal mines according to claim 1, characterized in that, The torque transmission head (6) includes a connecting post (601), a communication port (602) opened on the front of the connecting post (601), and a pressure chamber (603) opened on the outer wall of the connecting post (601). The pressure chamber (603) is connected to the communication port (602). The latching mechanism (7) includes a movable latching block (701) movably disposed inside the pressure chamber (603), a second elastic element (702) acting on the movable latching block (701) to give it a tendency to retract, and a dynamic sealing ring (703) fixedly sleeved on the outer periphery of the rear end of the movable latching block (701). When the fluid pressure in the pressure chamber (603) reaches the first preset value, the movable block (701) extends outward against the force of the second elastic element (702) and engages with the slot (305) in the bayonet (304); when the pressure chamber (603) is depressurized, the movable block (701) retracts under the action of the second elastic element (702).

6. The mid-drive casing lowering system for directional long boreholes in coal mines according to claim 5, characterized in that, The drill bit (4) includes a drill rod body (401) and a drill rod channel (402) disposed inside the drill rod body (401). The drill rod body (401) is detachably inserted into the communication port (602), and the drill rod channel (402) is connected to the communication port (602).

7. The coal mine underground directional long borehole mid-drive casing lowering system according to claim 5 or 6, characterized in that, The connecting column (601) is also provided with a flushing channel (9), the inlet of the flushing channel (9) is connected to the connecting port (602), and the outlet of the flushing channel (9) is directed toward the engagement area of ​​the movable block (701) and the slot (305); the flushing channel (9) is provided with a pressure control valve (10), and the opening pressure of the pressure control valve (10) is higher than the first preset value.

8. The underground directional long borehole mid-drive casing lowering system according to claim 7, characterized in that, The movable card block (701) is provided with a guide groove (11), which is matched with the outlet of the flushing channel (9); the rotating ring (303) is provided with a trumpet-shaped guide cover (12) at one end facing the wellhead, and the large end of the guide cover (12) faces the wellhead.

9. The mid-drive casing lowering system for directional long boreholes in coal mines according to any one of claims 1 to 8, characterized in that, A magnetic drive element (13) is provided on the outer periphery of the rotating ring (303); a magnetic actuator (14) and an impact generating assembly (15) are also provided in the drive tube section (3). The magnetic actuator (14) includes a hydraulic chamber (1403) opened inside the assembly ring (302), an assembly piece (1402) fixed on the inner wall of the assembly ring (302), a magnetic piston (1401) movably sleeved inside the assembly piece (1402), and a third elastic element (1404) fixedly connected to the magnetic piston (1401). The other end of the third elastic element (1404) is fixed in the hydraulic chamber (1403). The magnetic piston (1401) moves in response to the magnetic drive element (13). The impact generating assembly (15) The assembly includes a fixed sleeve (1502) fixed to the end of the assembly ring (302) and communicating with the hydraulic chamber (1403), a piston rod (1501) movably sleeved inside the fixed sleeve (1502) at one end, a fourth elastic element (1504) sleeved on the piston rod (1501), and a fixed block (1503) fixed on the inner wall of the tube body (301). The piston rod (1501) impacts the fixed block (1503) axially under the drive of fluid pressure. When the rotating ring (303) is idling, the rotating magnetic drive element (13) periodically drives the magnetic piston (1401), which transmits the motion to the impact generating assembly (15) through the compression hydraulic chamber (1403) and drives the piston rod (1501) to generate an axial impact.

10. A method for driving casing installation in the middle of a long directional borehole in a coal mine, characterized in that... The casing installation system as described in any one of claims 1 to 9 includes the following steps: Step 1: Connect the pipe string containing at least one drive pipe section (3) and feed it into the borehole; Step 2: The torque transmission head (6) is delivered to the drive pipe section (3) through the drill bit (4), and the torque transmission head (6) is inserted into the bayonet (304) of the rotating ring (303). Step 3: Inject fluid into the drill bit (4) to make the fluid pressure reach the first preset value, drive the snap-fit ​​mechanism (7) to act, and make the torque transmission head (6) engage with the rotating ring (303); Step 4: By applying axial thrust and rotational torque through the drill bit (4), the rotating ring (303) is driven to rotate in the first rotation direction. The one-way transmission assembly (5) drives the drive pipe section (3) and the pipe string to rotate synchronously, thereby realizing the push-rotation-down insertion. Step 5: When it is necessary to adjust the direction or prevent the threads from loosening, control the drill bit (4) to apply a torque in a second rotation direction opposite to the first rotation direction. At this time, the rotating ring (303) will rotate freely and will not drive the pipe string. Step 6: After the lowering operation is completed, reduce the fluid pressure in the clamping mechanism (7) to retract and disengage the clamping mechanism (7), and withdraw the drill bit (4) and torque transmission head (6); wherein, before disengagement, the fluid pressure in the drill bit (4) can be increased to a second preset value higher than the first preset value, so that the high-pressure fluid flushes the clamping area between the torque transmission head (6) and the rotating ring (303).

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