Well drilling device with ultra-long drill rod and well drilling method

Abstract

The invention relates to the technical field of drilling, in particular to a drilling device with an ultra-long drill rod and a drilling method. The super-long drill rod well drilling device comprises a drill bit and a lengthening rod connected to the tail end of the drill bit, a liquid cavity is formed in the lengthening rod, cooling liquid is contained in the liquid cavity, a flow guide cavity is formed in the drill bit, a variable-diameter rod is arranged at the bottom end of the lengthening rod, a variable-diameter cavity is formed in the top of the flow guide cavity, and the variable-diameter rod is arranged in the variable-diameter cavity. Matched thread structures are arranged between the outer wall of the variable-diameter rod and the cavity wall of the variable-diameter cavity, a through hole is formed in the variable-diameter rod, a sinking cavity is formed in the top end of the through hole and communicated with the bottom end of the liquid cavity, the hole diameter of the sinking cavity is smaller than the cavity diameter of the liquid cavity, and the diameter of the sinking cavity is larger than that of the liquid cavity. The bottom end of the through hole is communicated with the flow guide cavity, a heat collection cavity is formed in the bottom end of the flow guide cavity, the heat collection cavity is filled with an expansion medium, and compared with the prior art, the cooling mode has the advantages that cooling liquid is reasonably applied, and waste is reduced.

Description

Technical Field

[0001] The present invention relates to the technical field of drilling sampling, and particularly relates to an ultra-long drill pipe drilling device and a drilling method. Background Art

[0002] One end of a drill pipe is connected to a drilling machine, and a drill bit is installed at the other end. One or more sections of the drill pipe are assembled together. When the drilling machine drives the drill pipe to rotate, power is provided to the drill bit by the drill pipe, and a deep well is drilled. In order to improve the drilling efficiency and enable the drill bit to dissipate heat during deep well drilling to improve its service life, a drill pipe is disclosed in Chinese Patent with the application number 201910238560.3. Water flows into the drill pipe body through a water inlet. The body is communicated with a water storage cavity. The water flows into the water storage cavity and then enters the right connecting rod through a connecting channel. When multiple drill pipes are connected, the water flows from the water storage cavity of one drill pipe to the water storage cavity of another drill pipe. During its cooling operation, the water flow state is not controlled. If the heat of the drill bit is relatively low and it also dissipates heat through water flow, it will cause excessive waste of water. The drill pipe and the drill bit are only connected by threads, and the torque force of the drill pipe is relatively large during drilling. When rotating in the reverse direction, the threads will become loose, resulting in the drill bit falling off the drill pipe and affecting the construction. Summary of the Invention In order to solve the above problems, the present invention provides the following solutions: An ultra-long drill pipe drilling device includes a drill bit and an extension rod connected to the tail end of the drill bit. A liquid cavity is formed in the extension rod, and a coolant is contained in the liquid cavity. A diversion cavity is formed in the drill bit. A reducing rod is provided at the bottom end of the extension rod. A reducing cavity is formed at the top of the diversion cavity. A mutually matching thread structure is formed between the outer wall of the reducing rod and the cavity wall of the reducing cavity. A through hole is formed in the reducing rod. A sunken cavity is formed at the top end of the through hole. The sunken cavity is communicated with the bottom end of the liquid cavity, and the aperture of the sunken cavity is smaller than the cavity diameter of the liquid cavity. The bottom end of the through hole is communicated with the diversion cavity. A heat collection cavity is formed at the bottom end of the diversion cavity. An expansion medium is filled in the heat collection cavity. The heat collection cavity is close to the terminal of the drill bit. A stepped hole is formed between the top end of the heat collection cavity and the bottom end of the diversion cavity. A temperature reduction structure is provided on the drill bit and the extension rod. The temperature reduction structure includes a floating rod penetrating through the diversion cavity, and further includes an upper floating seat fixed to the top end of the floating rod and a lower floating seat fixed to the bottom end of the floating rod. The upper floating seat falls into the sunken cavity under the pressure of the coolant to block the through hole. Under the limitation of the position of the upper floating seat, the floating rod restricts the lower floating seat at the bottom end in the stepped hole to close the top end of the heat collection cavity. The bottom end of the lower floating seat is inserted into the heat collection cavity. A throwing hole is formed from the outer wall of the drill bit to the bottom end of the diversion cavity.

[0003] Preferably, drilling threads are provided along the bottom end to the top end of the outer wall surface of the drill bit.

[0004] Preferably, the cavity diameter of the heat collecting cavity is larger than that of the diversion cavity. The flinging holes are located above the heat collecting cavity. The flinging holes are several in an annular array. The outer ends of the flinging holes are inclined downward along the outer wall of the drill bit. A copper seat is embedded at the bottom of the heat collecting cavity, and the bottom end of the copper seat is close to the bottom end of the drill bit.

[0005] Preferably, a diversion channel is formed between the stepped hole and the cavity wall of the diversion cavity. Preferably, a first chamfer is provided at the bottom edge of the floating seat, and a second chamfer is provided at the top edge of the sunken cavity.

[0006] Preferably, an annular drilling part is provided on the outer surface of the bottom end of the extension rod, and the drilling part gradually protrudes outward toward the bottom end of the extension rod.

[0007] Preferably, upper positioning holes are provided upward from the bottom end of the extension rod. The upper positioning holes are three in an annular array. Lower positioning holes are provided downward from the top end of the drill bit. The lower positioning holes are three in an annular array. Counterbores are provided downward from the top end of each lower positioning hole. A positioning rod is provided in each lower positioning hole. A lifting part is provided at the top end of the positioning rod. The diameter of the lifting part is larger than that of the positioning rod. The outer circular surface of the lifting part is slidably fitted in the counterbore. A spring is provided in the counterbore. The spring is sleeved on the positioning rod. The top end of the spring abuts against the bottom surface of the lifting part, and the bottom end of the spring abuts against the bottom surface of the counterbore. The bottom end of the counterbore reaches the middle of the positioning hole. A positioning part perpendicular to the upward direction is provided at the top end of the lifting part. Under the support of the top end of the spring, the positioning part is inserted into the upper positioning hole of the extension rod. Positioning grooves are provided downward from the top end of the drill bit and are respectively located outside the three positioning holes. An operating part that slides in the three positioning grooves respectively is provided on the lifting part at the top end of each positioning rod. An operating ring is commonly installed around the three operating parts. Preferably, a channel is provided between the top end of the upper positioning hole and the bottom end of the liquid cavity. Part of the coolant in the liquid cavity is distributed into the upper positioning hole through the channel. The temperature reduction structure further includes an L-shaped flow channel provided downward from the top end of the lifting part to the middle of the side part of the lifting part. The temperature reduction structure further includes a pressing ring provided on the outer edge of the bottom end of the operating ring. The drilling part is close to above the operating ring. The temperature reduction structure further includes a thermal expansion tube filled between the bottom end of the extension rod and the pressing ring. Cooling holes are provided from the counterbore to the outer wall of the drill bit.

[0008] The present invention also provides a drilling method, which is applicable to the ultra-long drill pipe drilling device as described above, and includes the following steps: Step S01: Connect the drill bit and the extension rod together through the threaded structure; Step S02: Fill the liquid cavity with coolant, connect the top end of the extension rod to the drilling rig, place the bottom end of the drill bit at the drilling position in the mining area, drive the extension rod by the drilling rig, and drive the drill bit to rotate by the extension rod to complete the drilling operation.

[0009] The beneficial effects of the present invention compared with the prior art are as follows: A cooling structure is provided between the drill bit and the extension rod, and a heat collecting cavity is provided at the bottom of the drill bit. When drilling, heat is generated by the drill bit, and the heat is transferred to the heat collecting cavity, resulting in a gradual increase in the air pressure in the heat collecting cavity. When the air pressure increases to exceed the expansion coefficient of the expansion medium, it will push the lower floating seat of the cooling structure to rise, the lower floating seat pushes the floating rod to rise, and the floating rod pushes the upper floating seat to rise, and the sinking cavity opens, making the diversion cavity communicate with the liquid cavity up and down. At this time, the coolant in the liquid cavity will enter the diversion channel, and then flow to the throwing holes through the diversion channel. There are several throwing holes, and they are arranged in an annular array on the drill bit. The drill bit continues to rotate and drill, and generates centrifugal force. The centrifugal force is used to throw the coolant in the throwing holes into the drilling hole, flow along the inner wall of the rock ore to the outer wall of the drill bit, and then flow along the outer wall of the drill bit to the bottom, so that the drill bit is quickly cooled. The drill bit continues to rotate and continues to generate centrifugal force. The centrifugal force is used to throw the coolant into the drilling hole through the throwing holes. After the drill bit is cooled, the copper seat is cooled, and the heat collecting cavity will also be cooled. The expansion medium in the heat collecting cavity contracts when cooled, the lower floating seat drives the floating rod to descend, and the floating rod drives the upper floating seat to fall back into the sinking cavity, the diversion cavity and the liquid cavity are closed, and the coolant no longer enters the diversion cavity, and the cooling work stops. Compared with the prior art, the coolant is reasonably applied and waste is reduced.

[0010] Further, the reducing rod is connected to the reducing cavity through the threaded structure. After releasing the hand, the three springs rebound upward and provide elastic force to the three lifting parts. The elastic force is used to push the three lifting parts and the three lifting parts push the three positioning rods to rise, so that the top ends of the three positioning rods pop into the corresponding upper positioning holes. Since these three upper positioning holes are opened on the extension rod, when the extension rod and the drill bit are connected together through the threaded structure, they are restricted together by the three extension rods. During the drilling operation, the torque generated by the extension rod and the drill bit will not cause the threaded structure to loosen, ensuring that the extension rod and the drill bit are firmly connected. Description of the Drawings

[0011] Figure 1 It is a schematic diagram of an ultra-long drill pipe drilling device provided by an embodiment of the present invention; Figure 2 It is provided by an embodiment of the present invention Figure 1The enlarged schematic diagram of the A part is shown; Figure 3 A schematic diagram of a cross-section of an ultra-long drill pipe drilling device provided in an embodiment of the present invention; Figure 4 An ultra-long drill pipe drilling device provided by the embodiment of the present invention comprises Figure 3 The enlarged schematic diagram of the B part is shown; Figure 5 A schematic diagram of only a drill bit in an ultra-long drill pipe drilling device provided in an embodiment of the present invention; Figure 6 An ultra-long drill pipe drilling device provided by the embodiment of the present invention comprises Figure 5 The enlarged schematic diagram of the C part is shown; Figure 7 A schematic diagram of an ultra-long drill pipe drilling device provided by an embodiment of the present invention with only the drill bit cut away; Figure 8 An ultra-long drill pipe drilling device provided by the embodiment of the present invention comprises Figure 7 The enlarged schematic diagram of the D part is shown; Figure 9 A schematic diagram of a super-long drill pipe drilling device provided by an embodiment of the present invention after only the extension rod is cut away; Figure 10 A schematic diagram of an ultra-long drill pipe drilling device provided in an embodiment of the present invention, viewed from an upward perspective showing only an extended rod.

[0012] In the figure: 1. drill bit; 2. extension rod; 3. liquid chamber; 5. guide chamber; 6. reducing rod; 7. reducing chamber; 8. threaded structure; 9. through hole; 10. sink chamber; 11. heat collecting chamber; 12. step hole; 13. cooling structure; 14. floating rod; 15. upper floating seat; 16. lower floating seat; 17. ejection hole; 18. guide channel; 19. first chamfer; 20. second chamfer; 21. copper seat; 22. drilling part; 23. upper positioning hole; 24. lower positioning hole; 25. sink hole; 26. positioning rod; 27. lifting part; 28. spring; 29. ​​positioning part; 30. positioning groove; 31. operating part; 32. operating ring; 33. channel; 34. L-shaped flow channel; 35. pressure ring; 36. thermal expansion tube; 37. cooling hole. DETAILED DESCRIPTION

[0013] The above and other embodiments and advantages of the present invention are described clearly and completely below in conjunction with the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments.

[0014] In one embodiment, Figures 1 - 10As shown: This embodiment provides an ultra-long drill pipe drilling device, including a drill bit 1 and an extension rod 2 connected to the tail end of the drill bit 1. A liquid cavity 3 is formed inside the extension rod 2, and a coolant is filled in the liquid cavity 3. A diversion cavity 5 is formed inside the drill bit 1. A reducing rod 6 is provided at the bottom end of the extension rod 2. A reducing cavity 7 is formed at the top of the diversion cavity 5. A mutually matching thread structure 8 is formed between the outer wall of the reducing rod 6 and the cavity wall of the reducing cavity 7. A through hole 9 is formed on the reducing rod 6. A sunken cavity 10 is formed at the top end of the through hole 9. The sunken cavity 10 communicates with the bottom end of the liquid cavity 3, and the aperture of the sunken cavity 10 is smaller than the cavity diameter of the liquid cavity 3. The bottom end of the through hole 9 communicates with the diversion cavity 5. A heat collection cavity 11 is formed at the bottom end of the diversion cavity 5. An expansion medium is filled in the heat collection cavity 11. The heat collection cavity 11 is close to the terminal of the drill bit 1. A stepped hole 12 is formed between the top end of the heat collection cavity 11 and the bottom end of the diversion cavity 5.

[0015] Drilling threads are formed along the bottom end to the top end of the outer wall surface of the drill bit 1.

[0016] The cavity diameter of the heat collection cavity 11 is larger than that of the diversion cavity 5. The throwing holes 17 are located above the heat collection cavity 11. The throwing holes 17 are several in an annular array. The outer ends of the throwing holes 17 are inclined downward along the outer wall of the drill bit 1. A copper seat 21 is embedded at the bottom of the heat collection cavity 11. The bottom end of the copper seat 21 is close to the bottom end of the drill bit 1.

[0017] A diversion channel 18 is formed between the stepped hole 12 and the cavity wall of the diversion cavity 5. A first chamfer 19 is provided at the bottom edge of the floating seat 15, and a second chamfer 20 is provided at the top edge of the sunken cavity 10.

[0018] An annular drilling part 22 is provided on the outer surface of the bottom end of the extension rod 2. The drilling part 22 gradually bulges outward in the direction of the bottom end of the extension rod 2.

[0019] An upper positioning hole 23 is opened upward from the bottom end of the extension rod 2, and there are three upper positioning holes 23 arranged in an annular array. A lower positioning hole 24 is opened downward from the top end of the drill bit 1, and there are three lower positioning holes 24 arranged in an annular array. A counterbore 25 is opened downward from the top end of each lower positioning hole 24. A positioning rod 26 is arranged in each lower positioning hole 24. A lifting part 27 is arranged at the top end of the positioning rod 26. The diameter of the lifting part 27 is larger than that of the positioning rod 26. The outer circumferential surface of the lifting part 27 is slidably fitted in the counterbore 25. A spring 28 is arranged in the counterbore 25. The spring 28 is sleeved on the positioning rod 26. The top end of the spring 28 abuts against the bottom surface of the lifting part 27, and the bottom end of the spring 28 abuts against the bottom surface of the counterbore 25. The bottom end of the counterbore 25 reaches the middle of the positioning hole 24. A positioning part 29 perpendicular to the upward direction is arranged at the top end of the lifting part 27. Supported by the top end of the spring 28, the lifting part 27 inserts the positioning part 29 into the upper positioning hole 23 of the extension rod 2. Three positioning grooves 30 are opened downward from the top end of the drill bit 1 and are respectively located outside the three positioning holes 24. An operating part 31 slidably arranged in each of the three positioning grooves 30 is arranged on the lifting part 27 at the top end of each positioning rod 26. An operating ring 32 is commonly installed around the three operating parts.

[0020] During use, first connect the drill bit 1 and the extension rod 2 together through the threaded structure 8. Before docking, push down the operating ring 32. The operating ring 32 drives the three operating parts 31 to descend along the positioning grooves 30. The three operating parts 31 drive the three positioning rods 26 to descend. The three positioning rods 26 drive the three positioning parts 29 to descend into the corresponding counterbores 25. The bottom end of the positioning rod 26 descends along the lower positioning hole 24, and the spring 28 is compressed in the counterbore 25 by using the lifting part 27. At this time, the top surface of the drill bit 1 is flat. Then align the variable diameter rod 6 with the variable diameter cavity 7 and rotate it. Connect the variable diameter rod 6 to the variable diameter cavity 7 through the threaded structure 8. After releasing the hand, the three springs 28 rebound upward and provide elastic force to the three lifting parts 27. The elastic force pushes the three lifting parts 27, and the three lifting parts 27 push the three positioning rods 26 to rise, so that the top ends (positioning parts 29) of the three positioning rods 26 pop into the corresponding upper positioning holes 23. Since these three upper positioning holes 23 are opened on the extension rod 2, when the extension rod 2 and the drill bit 1 are connected together through the threaded structure 8, they are restricted together by the three extension rods 2. During the drilling operation, the torque generated by the extension rod 2 and the drill bit 1 will not cause the threaded structure 8 to loosen, ensuring the firm connection between the extension rod 2 and the drill bit 1.

[0021] In addition, a first cooling structure 13 is provided on the drill bit 1 and the extension rod 2. The cooling structure 13 includes a floating rod 14 inserted into the diversion cavity 5, and further includes an upper floating seat 15 fixed to the top end of the floating rod 14 and a lower floating seat 16 fixed to the bottom end of the floating rod 14. The upper floating seat 15 falls into the sinking cavity 10 under the pressure of the coolant to block the through hole 9. Under the limitation of the position where the upper floating seat 15 is located, the floating rod 14 restricts the lower floating seat 16 at the bottom end in the stepped hole 12 to seal the top end of the heat collection cavity 11. The bottom end of the lower floating seat 16 is inserted into the heat collection cavity 11, and a liquid throwing hole 17 is provided from the outer wall of the drill bit 1 to the bottom end of the diversion cavity 5. Specifically, when the drill bit 1 drills a deep well, as the drilling depth continuously increases, heat will be generated between its outer wall and the rock formation. As the heat gradually accumulates at the head and is transmitted to the copper seat 21, it is gradually released into the heat collection cavity 11 through the copper seat 21. As the heat gradually rises in temperature, the air pressure in the heat collection cavity 11 will gradually increase. When the air pressure increases beyond the expansion coefficient of the expansion medium (such as an expander), it will push the lower floating seat 16 to rise. The lower floating seat 16 pushes the floating rod 14 to rise, and the floating rod 14 pushes the upper floating seat 15 to rise, opening the sinking cavity 10, making the diversion cavity 5 communicate with the liquid cavity 3 up and down. At this time, the coolant in the liquid cavity 3 will enter the diversion channel 18, and then flow to the liquid throwing holes 17 through the diversion channel 18. There are several liquid throwing holes 17, which are arranged in an annular array on the drill bit 1. The drill bit 1 continues to rotate and drill, generating centrifugal force. The centrifugal force is used to throw the coolant in the liquid throwing holes 17 into the drill hole, flow along the inner wall of the rock ore to the outer wall of the drill bit 1, and then flow to the bottom along the outer wall of the drill bit 1, quickly cooling the drill bit 1. The drill bit 1 continues to rotate, continuously generating centrifugal force, and the centrifugal force is used to continue to throw the coolant through the liquid throwing holes 17 into the drill hole. After the drill bit 1 is cooled, the copper seat 21 is cooled, and the heat collection cavity 11 will also be cooled. The expansion medium in the heat collection cavity 11 contracts when cooled, the lower floating seat 16 drives the floating rod 14 to descend, and the floating rod 14 drives the upper floating seat 15 to fall back into the sinking cavity 10. The diversion cavity 5 and the liquid cavity 3 are closed, and the coolant no longer enters the diversion cavity 5, and the cooling work stops. Compared with the prior art, the coolant is reasonably applied and waste is reduced.

[0022] In addition, a second cooling structure 13 is provided on the drill bit 1 and the extension rod 2. A channel 33 is formed between the top end of the upper positioning hole 23 and the bottom end of the liquid cavity 3. Part of the coolant in the liquid cavity 3 is distributed into the upper positioning hole 23 through the channel 33. The second cooling structure 13 further includes an L-shaped flow channel 34 that is opened downward from the top end of the lifting part 27 to the middle of the side of the lifting part 27. The cooling structure 13 further includes a pressing ring 35 arranged on the outer edge of the bottom end of the operation ring 32. The drilling part 22 is close to above the operation ring 32. The cooling structure 13 further includes a thermal expansion tube 36 filled between the bottom end of the extension rod 2 and the pressing ring 35. A cooling hole 37 is formed from the counterbore 25 to the outer wall of the drill bit 1. Specifically, when the drill bit 1 drills a hole, it will also drive the extension rod 2 to rotate together. The extension rod 2 uses the protruding drilling part 22 to participate in the reaming work, making the wellbore thicker. When the drilling is completed, it is beneficial for the drill bit 1 to be lifted upward. In addition, when the drilling part 22 participates in the reaming work, it will also generate heat. The heat is transferred to the thermal expansion tube 36, causing the thermal expansion tube 36 to expand in the axial direction and push the pressing ring 35 downward. The pressing ring 35 pushes the operation ring 32 downward. The operation ring 32 drives the three positioning rods 26 to descend significantly. The positioning rods 26 drive the lifting part 27 to descend into the counterbore 25, and the spring 28 is compressed and shortened. At this time, the outer end of the L-shaped flow channel 34 communicates with the counterbore 25, enabling the coolant distributed in the channel 33 to flow into the corresponding counterbore 25 through the L-shaped flow channel 34. With the centrifugal force generated when the extension rod 2 rotates, these coolants are thrown onto the rock and ore reaming participated by the drilling part 22 through the cooling holes 37 and flow downward along the reamed hole wall to the drilling part 22, enabling the drilling part 22 to be cooled and improving the tool life of the drilling part 22. After the drilling part 22 is cooled, the thermal expansion tube 36 retracts and shortens, and the spring 28 returns to its original length and pushes the lifting part 27 upward. The lifting part 27 drives the positioning rod 26 to rise, causing the L-shaped flow channel 34 to rise with the positioning part 29 into the upper positioning hole 23. At this time, the L-shaped flow channel 34 also rises into the upper positioning hole 23, and the outer end of the L-shaped flow channel 34 is closed, and the coolant is blocked in the channel 33 again. The coolant also achieves the purpose of reasonable application and waste reduction.

[0023] It should be further noted that when selecting the thermal expansion tube 36, its maximum expansion is limited to the situation where the lifting part 27 descends to make the bottom end of the L-shaped flow channel 34 fall into the counterbore 25, and the top end of the lifting part 27 still remains in the upper positioning hole 23, without affecting the positioning relationship between the drill bit 1 and the extension rod 2.

[0024] The present invention also provides a drilling method, which is applicable to the ultra-long drill pipe drilling device as described above, including the following steps: Step S01: Connect the drill bit 1 and the extension rod 2 together through the threaded structure 8; before that, load the expansion agent into the heat collecting cavity 11 of the drill bit 1. Step S02: Fill the liquid cavity 3 with coolant, connect the top end of the extension rod 2 to the drill rig, place the bottom end of the drill bit 1 at the drilling position in the mining area, drive the extension rod 2 by the drill rig, and drive the drill bit 1 to rotate by the extension rod 2 to complete the drilling operation.

[0025] The above orientation references do not represent the specific orientations of the components in this implementation solution. This implementation solution is only for the convenience of describing the solution and is set with relative descriptions with reference to the orientations in the figure. In essence, the specific orientations of the components are based on their actual installation, actual use, and the habitual orientation descriptions of those skilled in the art. This is hereby stated.

[0026] The specific implementation manners described above further elaborate on the invention purpose, technical solution, and beneficial effects of the present invention. It should be understood that the above is only the specific implementation manner of the present invention and is not used to limit the protection scope of the present invention. It is particularly pointed out that for those skilled in the art, any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present invention shall be included within the protection scope of the present invention.

Claims

1. An ultra-long drill pipe drilling device, characterized in that: The drill bit (1) comprises a drill bit (1) and an extension rod (2) connected to the rear end of the drill bit (1), the extension rod (2) being provided with a liquid chamber (3), the liquid chamber (3) being filled with cooling liquid, the drill bit (1) being provided with a flow guide chamber (5), the bottom end of the extension rod (2) being provided with a diameter reducing rod (6), the top of the flow guide chamber (5) being provided with a diameter reducing chamber (7), the outer wall of the diameter reducing rod (6) and the cavity wall of the diameter reducing chamber (7) being provided with mutually matching threaded structures (8), the A through hole (9) is provided on the diameter-changing rod (6), a sinking cavity (10) is provided at the top of the through hole (9), the sinking cavity (10) is communicated with the bottom end of the liquid cavity (3), and the aperture of the sinking cavity (10) is smaller than the cavity diameter of the liquid cavity (3), the bottom end of the through hole (9) is communicated with the flow guiding cavity (5), a heat collecting cavity (11) is provided at the bottom end of the flow guiding cavity (5), the heat collecting cavity (11) is filled with an expansion medium, and the heat collecting cavity (11) is close to the drill bit (1 ), a stepped hole (12) is provided between the top of the heat collecting cavity (11) and the bottom of the flow guiding cavity (5), a cooling structure (13) is provided on the drill bit (1) and the extension rod (2), the cooling structure (13) comprises a floating rod (14) penetrating the flow guiding cavity (5), an upper floating seat (15) fixed to the top of the floating rod (14) and a lower floating seat (16) fixed to the bottom of the floating rod (14), the upper floating seat (15) being arranged in a cooling state. The liquid falls into the sinking cavity (10) under the action of pressure, so as to block the through hole (9); the floating rod (14) is limited by the position of the upper floating seat (15), so as to limit the lower floating seat (16) at the bottom end within the step hole (12), so as to close the top of the heat collection cavity (11); the bottom end of the lower floating seat (16) is inserted into the heat collection cavity (11), and a swing hole (17) is opened from the outer wall of the drill bit (1) to the bottom end of the guide cavity (5).

2. The ultra-long drill pipe drilling device according to claim 1, characterized in that: A drilling thread is provided along the bottom end of the outer wall surface of the drill bit (1) toward the top end.

3. The ultra-long drill pipe drilling device according to claim 1, characterized in that: The diameter of the heat collection cavity (11) is larger than the diameter of the flow guide cavity (5); the ejection holes (17) are located above the heat collection cavity (11); the ejection holes (17) are a plurality of ejection holes in a circular array; the outer ends of the ejection holes (17) are inclined downward along the outer wall of the drill bit (1); a copper seat (21) is inlaid at the bottom of the heat collection cavity (11); and the bottom end of the copper seat (21) is close to the bottom end of the drill bit (1).

4. The ultra-long drill pipe drilling device according to claim 1, characterized in that: A flow guide channel (18) is formed between the step hole (12) and the cavity wall of the flow guide cavity (5).

5. The ultra-long drill pipe drilling device according to claim 1, characterized in that: The bottom edge of the floating seat (15) is provided with a first chamfer (19), and the top edge of the sink cavity (10) is provided with a second chamfer (20).

6. The ultra-long drill pipe drilling device according to claim 1, characterized in that: An annular drilling portion (22) is provided on the outer surface of the bottom end of the extension rod (2), and the drilling portion (22) gradually protrudes outwards towards the bottom end of the extension rod (2).

7. The ultra-long drill pipe drilling device according to claim 1, characterized in that: An upper positioning hole (23) is opened upward from the bottom end of the extension rod (2), and the upper positioning holes (23) are formed at three locations in a circular array. A lower positioning hole (24) is opened downward from the top end of the drill bit (1), and the lower positioning holes (24) are formed at three locations in a circular array. A countersunk hole (25) is opened downward from the top end of the lower positioning hole (24). A positioning rod (26) is arranged in each of the lower positioning holes (24). A lifting portion (27) is arranged at the top end of the positioning rod (26). The diameter of the lifting portion (27) is larger than the diameter of the positioning rod (26). The outer circumferential surface of the lifting portion (27) is slidably fitted in the countersunk hole (25). A spring (28) is arranged in the countersunk hole (25). The spring (28) is sleeved on the positioning rod (26). The top end of the spring (28) is pressed against the positioning rod (26). On the bottom surface of the lifting part (27), the bottom end of the spring (28) is pressed against the bottom end surface of the countersunk hole (25), and the bottom end of the countersunk hole (25) reaches the middle of the positioning hole (24). A vertically upward positioning part (29) is provided at the top end of the lifting part (27). Under the support of the top end of the spring (28), the lifting part (27) inserts the positioning part (29) into the upper positioning hole (23) of the extension rod (2). Three positioning grooves (30) are respectively located outside the three positioning holes (24) from the top end of the drill bit (1). The lifting part (27) at the top end of the positioning rod (26) is provided with an operating part (31) that slides in the three positioning grooves (30) respectively. An operating ring (32) is commonly installed on the periphery of the three operating parts (31).

8. The ultra-long drill pipe drilling device according to claim 7, characterized in that: A channel (33) is provided between the top end of the upper positioning hole (23) and the bottom end of the liquid chamber (3), and part of the cooling liquid in the liquid chamber (3) is distributed into the upper positioning hole (23) through the channel (33). The cooling structure (13) further comprises an L-shaped flow channel (34) extending downward from the top end of the lifting portion (27) to the middle of the side of the lifting portion (27). The cooling structure (13) further comprises a pressure ring (35) arranged on the outer edge of the bottom end of the operating ring (32), and the drilling portion (22) is close to the top of the operating ring (32). The cooling structure (13) further comprises a thermal expansion tube (36) filled between the bottom end of the extension rod (2) and the pressure ring (35). A cooling hole (37) is provided from the countersunk hole (25) to the outer wall of the drill bit (1).

9. A drilling method, applicable to the ultra-long drill pipe drilling device according to claim 1, characterized in that: The following steps are involved: Step S01, connecting the drill bit (1) and the extension rod (2) together via the threaded structure (8); Step S02, coolant is filled into the liquid chamber (3), the top end of the extension rod (2) is connected to the drilling rig, the bottom end of the drill bit (1) is placed on the drilling position in the mining area, the drilling rig drives the extension rod (2), and the extension rod (2) drives the drill bit (1) to rotate, thereby completing the drilling operation.

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