An inner tube assembly and wire-line coring drill

Abstract

This invention discloses an inner tube assembly and a wireline coring tool, belonging to the technical field of drilling and coring tools. It includes an outer tube, an inner tube body, a core retrieval mechanism, and a ball-dropping and clamping mechanism. A drill bit is connected to the end of the outer tube. The inner tube body is fitted inside the outer tube. The core retrieval mechanism includes a core claw connected to the inner tube body. After the inner tube body moves towards the drill bit, the core claw retracts towards its inner diameter due to the contact with the drill bit. The ball-dropping and clamping mechanism includes a sliding sleeve, a suspension ring, and a lower suspension joint. The sliding sleeve is fitted onto the inner diameter side of the suspension ring. The suspension ring is connected to the lower suspension joint via a first ball-clamping structure. The suspension ring is connected to the inner tube body, and the lower suspension joint is connected to the outer tube. This invention utilizes the ball-dropping and clamping mechanism to drive the core retrieval mechanism, achieving efficient and reliable coring operations.

Description

Technical Field

[0001] This invention relates to the field of drilling and coring tools, and in particular to an inner tube assembly and a wireline coring tool. Background Technology

[0002] In drilling projects, conventional wireline coring tools can achieve good coring results in relatively hard and well-formed strata, but they have many problems when dealing with loose, soft and fractured strata.

[0003] Traditional drilling tools often lack effective core-catching devices to seal cores inside the inner casing, leading to significant core loss during drilling and resulting in low core recovery rates. For example, sedimentary strata in marine and lacustrine drilling are poorly cemented, weak, and prone to collapse and loss; while fractured rock formations in continental scientific drilling present challenges in core retrieval due to difficulty in core retention and easy core detachment during drilling. Existing conventional drilling tools are insufficient to meet the core recovery requirements of these formations.

[0004] Currently, although some improvements have been made, such as using semi-composite pipes, triple-layer pipes, and advance pipes, the problem has not been fundamentally solved. Therefore, it is essential to develop a drilling tool that can effectively cored loose, soft, and fractured formations. Summary of the Invention

[0005] The purpose of this invention is to provide an inner tube assembly and a wireline coring tool to solve the problems existing in the prior art. By using a ball-throwing and clamping mechanism to drive the core retrieval mechanism, efficient and reliable coring operations can be achieved.

[0006] To achieve the above objectives, the present invention provides the following solution:

[0007] This invention provides an inner tube assembly, including an outer tube, an inner tube body, a core retrieval mechanism, and a ball-throwing and clamping mechanism. A drill bit is connected to the end of the outer tube. The inner tube body is fitted inside the outer tube. The core retrieval mechanism includes a core claw connected to the inner tube body. After the inner tube body moves towards the drill bit, the core claw retracts towards its inner diameter due to the contact with the drill bit. The ball-throwing and clamping mechanism includes a sliding sleeve, a suspension ring, and a lower suspension joint. The sliding sleeve is fitted onto the inner diameter side of the suspension ring. The suspension ring is connected to the lower suspension joint via a first ball-clamping structure. The suspension ring is connected to the inner tube body, and the lower suspension joint is connected to the outer tube.

[0008] In one embodiment, the core retrieval mechanism further includes a core claw seat, which is connected to the inner tube body via a lower connector. The free end of the core claw has multiple circumferentially distributed lobes, which are capable of deforming towards the inner diameter side.

[0009] In one embodiment, the first ball-clamping structure includes a first suspended steel ball and a first spring. The suspension ring has a radially penetrating first ball hole. The outer diameter side of the sliding sleeve is provided with a first one-way ball-clamping groove, and the inner diameter side of the lower suspension joint is provided with a first two-way ball-clamping groove. One end of the first spring abuts against the sliding sleeve, and the other end of the first spring abuts against the inner flange of the suspension ring. When the sliding sleeve moves toward the drill bit, the first suspended steel ball can enter the first one-way ball-clamping groove from the first two-way ball-clamping groove, causing the suspension ring to disengage from the lower suspension joint.

[0010] In one embodiment, a buffer mechanism is further included, the buffer mechanism comprising a central shaft and a second spring, the central shaft having a shoulder, one end of the second spring abutting against the suspension ring, the other end of the second spring abutting against the shoulder, and the end of the central shaft away from the suspension ring being connected to the inner tube body.

[0011] In one embodiment, a single-action mechanism is further included. The single-action mechanism includes a rotating component and an anti-rotation component. The rotating component includes an upper bearing, a lower bearing, and a bearing cavity. The bearing cavity is sleeved on the outer diameter side of the central shaft and connected to the suspension ring. The upper bearing and the lower bearing are both located between the central shaft and the bearing cavity. In the axial direction, the upper bearing is located between the second spring and the suspension ring, and the lower bearing is located between the shaft shoulder and the bearing cavity. The anti-rotation component is connected between the central shaft and the inner tube body.

[0012] In one embodiment, the anti-rotation assembly includes an inner tube connector, a key, and a pressure cap. The inner diameter side of the inner tube connector is threaded to the central shaft, and the outer diameter side of the inner tube connector is threaded to the inner tube body. The central shaft and the inner tube connector are provided with a keyway for inserting the key. The pressure cap is threaded to the central shaft and is used to axially press the inner tube body.

[0013] In one embodiment, a core-protecting water-blocking mechanism is also included. The core-protecting water-blocking mechanism includes a one-way valve and a jet channel and a drainage channel that are not interconnected and are opened axially along the central axis. The inlet of the jet channel is away from the drill bit, and the inlet of the drainage channel is close to the drill bit. The one-way valve is installed at the inlet of the drainage channel. A jet hole communicating with the jet channel is also opened on the central axis. The jet hole is obliquely oriented towards the drill bit. A drainage hole communicating with the drainage channel is also opened on the central axis. The drainage hole is obliquely oriented away from the drill bit.

[0014] In one embodiment, a suspension mechanism is further included, the suspension mechanism comprising an upper suspension joint and a seat ring, the seat ring being connected to the outer tube, the upper suspension joint being connected to the outer tube via a second ball clamp structure, the upper suspension joint being connected to the lower suspension joint, the upper suspension joint having a contact surface that connects to the seat ring, and the seat ring being used to limit the axial position of the upper suspension joint.

[0015] In one embodiment, the second ball-clamping structure includes a female retrieval spearhead, a spring seat, a third spring, and a second suspended steel ball. The upper suspension connector has a radially penetrating second ball hole. The outer diameter side of the female retrieval spearhead is provided with a second one-way ball-clamping groove, and the inner diameter side of the outer tube is provided with a second two-way ball-clamping groove. One end of the third spring abuts against the inner flange of the upper suspension connector, and the other end of the third spring abuts against the outer flange of the spring seat. When the female retrieval spearhead moves away from the drill bit, the second suspended steel ball can enter the second one-way ball-clamping groove from the second two-way ball-clamping groove, causing the upper suspension connector to disengage from the outer tube.

[0016] The present invention also provides a wireline coring tool, including an inner tube assembly as described above, and a retrieval device. The retrieval device includes a fixed joint, a male retrieval spearhead, and a fourth spring. The male retrieval spearhead is hinged to the fixed joint and connected to the fourth spring. The male retrieval spearhead can penetrate into the female retrieval spearhead and, after being reset under the action of the fourth spring, achieves the connection between the male retrieval spearhead and the female retrieval spearhead.

[0017] The present invention achieves the following technical effects compared to the prior art:

[0018] During the drilling process, this invention utilizes the inner tube body to accommodate the core. The inner tube body continues to move relative to the outer tube through the action of the ball-throwing and clamping mechanism, thereby abutting the core claw of the core retrieval mechanism against the drill bit. Under the action of the drill bit, the core claw is forced to retract towards the inner diameter side, thus retrieval the core into the inner tube body. This prevents the core from falling out during the retrieval of the inner tube body, achieving efficient and reliable core retrieval operations. Attached Figure Description

[0019] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0020] Figure 1 This is a schematic diagram of the inner tube assembly in an embodiment of the present invention;

[0021] Figure 2 for Figure 1 Schematic diagram of the upper part of the inner tube assembly;

[0022] Figure 3 for Figure 1 Schematic diagram of the lower half of the inner tube assembly;

[0023] Figure 4 This is a schematic diagram of the retrieval device in an embodiment of the present invention;

[0024] Figure 5 This is a schematic diagram of the de-carding tube in an embodiment of the present invention;

[0025] The components are as follows: 1. Mother spearhead; 2. Upper suspension connector; 3. Second suspension steel ball; 4. Second bidirectional snap-fit ​​ball groove; 5. Upper connector; 6. Third spring; 7. Seat ring; 8. Spring seat; 9. Pressure relief hole; 10. Sealing steel ball; 11. First suspension steel ball; 12. Sliding sleeve; 13. Lower suspension connector; 14. First spring; 15. Suspension ring; 16. Upper bearing; 17. Second spring; 18. Bearing cavity; 19. Lower bearing; 20. Jet hole; 21. Drain hole; 22. Central shaft; 23. Pressure cap; 24. Keyway; 25. Key; 26. Inner tube connector; 27. Valve ball; 28. One-way valve; 29. ​​Inner tube body; 30. Outer tube body; 31. Expander; 32. Lower connector; 33. Core claw seat; 34. Core claw; 35. Bottom nozzle; 36. Drill bit.

[0026] 201. Steel wire rope; 202. Pipa head; 203. Safety pin; 204. Weighting tube; 205. Impact ring; 206. Fixed joint; 207. Salvage hook positioning pin; 208. Unlocking ring; 209. Spring positioning pin; 210. Fourth spring; 211. Salvage spearhead; 212. Guide head;

[0027] 301. Unblocking the tube; 302. Spiral opening. Detailed Implementation

[0028] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0029] The purpose of this invention is to provide an inner tube assembly and a wireline coring tool to solve the problems existing in the prior art. By using a ball-dropping and clamping mechanism to drive the core clamping mechanism, efficient and reliable coring operations can be achieved.

[0030] To make the above-mentioned objects, features and advantages of the present invention more apparent and understandable, the present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0031] like Figures 1-3 As shown, this invention provides an inner tube assembly, including an outer tube, an inner tube body 29, a core retrieval mechanism, and a ball-dropping and clamping mechanism. The end of the outer tube can be directly or via a reamer 31 connected to a drill bit 36. The drill bit 36 ​​can rotate under the impact of drilling fluid to perform drilling operations. The inner tube body 29 is fitted inside the outer tube. The outer tube can rotate together with the inner tube body 29 or rotate relative to the inner tube body 29. The inner tube body 29 is used to hold the core. The relatively rotating inner tube body 29 is more conducive to retrieving the core and avoids wear on the core. The core retrieval mechanism includes a core claw 34 connected to the inner tube body 29. After the inner tube body 29 moves towards the drill bit 36, the core claw 34 is abutted by the drill bit 36 ​​(the top surface of the drill bit 36 ​​has an inner slope) and retracts towards its inner diameter. The core claw 34 retracts and deforms along the inner slope of the drill bit 36, clamping and sealing the core inside the inner tube body 29. The core claw 34 needs to possess sufficient strength, hardness, and elasticity. After retraction, the core claw 34 can form an interception structure to prevent the core from detaching from the inner tube body 29. The ball-dropping and clamping mechanism includes a sliding sleeve 12, a suspension ring 15, and a lower suspension joint 13. The sliding sleeve 12 is fitted onto the inner diameter side of the suspension ring 15 and can slide relative to it axially. The suspension ring 15 is connected to the lower suspension joint 13 via a first ball-clamping structure. When the sliding sleeve 12 is subjected to the action of the inserted sealing steel ball 10, under the pressure of the drilling fluid, it will push the sliding sleeve 12 towards the drill bit 36, thereby releasing the clamping state of the first ball-clamping structure, causing the suspension ring 15 to move towards the drill bit 36. The suspension ring 15 is connected to the inner tube body 29, and the lower suspension joint 13 is connected to the outer tube. Thus, when the suspension ring 15 moves, it can drive the inner tube body 29 to move relative to the outer tube, thereby completing the retraction action of the core claw 34.

[0032] It should be noted that the distance of movement of the suspension ring 15 is coordinated with the distance of movement and the contraction angle of the core claw 34 to ensure that the core claw 34 can retract into place.

[0033] During the drilling process, the inner tube body 29 accommodates the core. The inner tube body 29 continues to move relative to the outer tube through the action of the ball dropping and pressing mechanism. This causes the core claw 34 of the core retrieval mechanism to abut against the drill bit 36. Under the action of the drill bit 36, the core claw 34 is forced to retract towards the inner diameter side, thereby retrieval of the core into the inner tube body 29. This prevents the core from falling out during the retrieval of the inner tube body 29 and achieves efficient and reliable core retrieval operations.

[0034] In one embodiment, the core retrieval mechanism further includes a core claw seat 33, which is connected to the inner tube body 29 via a lower connector 32. The free end of the core claw 34 has multiple circumferentially distributed petals that can deform toward the inner diameter side. The deformation process of the petals is forced by the reaction force of the drill bit 36.

[0035] In one embodiment, the first ball-locking structure includes a first suspended steel ball 11 and a first spring 14. The suspension ring 15 has a radially penetrating first ball hole through which the first suspended steel ball 11 can pass. The outer diameter side of the sliding sleeve 12 is provided with a first one-way ball-locking groove, through which the first suspended steel ball 11 can enter and exit the first one-way ball-locking groove from one axial side, while the other axial side restricts the movement of the first suspended steel ball 11. The inner diameter side of the lower suspension joint 13 is provided with a first two-way ball-locking groove, through which the first suspended steel ball 11 can only enter and exit radially, and the movement of the first suspended steel ball 11 is restricted on both axial sides. One end of the first spring 14 abuts against the sliding sleeve 12, and the other end of the first spring 14 abuts against the inner flange of the suspension ring 15. Thus, in the snap-fit ​​state, the first spring 14 provides the sliding sleeve 12 with an upward pushing force, causing the first one-way snap-fit ​​ball groove to be misaligned with the first ball hole. At this time, the sliding sleeve 12 restricts the first suspension steel ball 11 to the first ball hole and the first two-way snap-fit ​​ball groove. When the snap-fit ​​is released, the sliding sleeve 12 moves toward the drill bit 36, overcoming the elastic force of the first spring 14, and the first suspension steel ball 11 can enter the first one-way snap-fit ​​ball groove from the first two-way snap-fit ​​ball groove, causing the suspension ring 15 to disengage from the lower suspension joint 13.

[0036] After core sampling is completed, the sealing steel ball 10 is inserted and the pump is turned on to pressurize. The sealing steel ball 10 falls and blocks the channel, causing the pump pressure to rise. This causes the sliding sleeve 12 to move downward. The first suspended steel ball 11 falls into the first one-way locking ball groove of the sliding sleeve 12. The connection between the suspension ring 15 and the lower suspension joint 13 fails. Under the action of the pump pressure, the suspension ring 15 moves downward, pushing the central shaft 22 and its lower connecting device to move downward. This causes the core claw 34 to retract and cut off, protecting the core. After the suspension ring 15 moves into position, it hangs on the step of the lower suspension joint 13. The lower suspension joint 13 has a radially penetrating pressure relief hole 9. When the suspension ring 15 moves into position, the pressure relief hole 9 is open to indicate that the locking is in place.

[0037] In one embodiment, a buffer mechanism is also included, which includes a central shaft 22 and a second spring 17. The central shaft 22 is provided with a shoulder, one end of the second spring 17 abuts against the suspension ring 15, and the other end of the second spring 17 abuts against the shoulder. The end of the central shaft 22 away from the suspension ring 15 is connected to the inner tube body 29. Thus, when drilling is pressurized, the second spring 17 can play a floating buffering role to protect the inner tube body 29 and the rock core inside the inner tube body 29.

[0038] In one embodiment, a single-action mechanism is also included. This single-action mechanism comprises a rotating component and an anti-rotation component. The rotating component includes an upper bearing 16, a lower bearing 19, and a bearing cavity 18. Both the upper bearing 16 and the lower bearing 19 can be thrust bearings. The bearing cavity 18 is fitted onto the outer diameter side of the central shaft 22 and connected to the suspension ring 15. An installation space for the upper bearing 16 and the lower bearing 19 is formed between the bearing cavity 18 and the central shaft 22. The bearing cavity 18 and the central shaft 22 can rotate relative to each other under the support of the upper bearing 16 and the lower bearing 19. In the axial direction, the upper bearing 16 is located between the second spring 17 and the suspension ring 15, and the lower bearing 19 is located between the shaft shoulder and the bearing cavity 18. The anti-rotation component is connected between the central shaft 22 and the inner tube body 29. By setting the anti-rotation component, the central shaft 22 and the inner tube body 29 are synchronously stationary, and the inner tube body 29 does not rotate with the outer tube, avoiding vibration damage to the core, reducing friction and load, and minimizing friction on the core.

[0039] In one embodiment, the anti-rotation assembly includes an inner tube connector 26, a key 25, and a pressure cap 23. The inner diameter side of the inner tube connector 26 is threadedly connected to the central shaft 22, and the outer diameter side of the inner tube connector 26 is threadedly connected to the inner tube body 29. Thus, the inner tube connector 26 can move up and down on the central shaft 22 via the thread, adjusting the gap between the core claw 34 and the drill bit 36. This ensures that the core claw 34 and the drill bit 36 ​​are within a suitable gap, providing the inner tube body 29 with axial buffer movement space and preventing shrinkage and deformation of the core claw 34 when coring is not performed. The central shaft 22 and the inner tube connector 26 are provided with a keyway 24 for inserting the key 25. After the inner tube connector 26 is adjusted to the correct position, inserting the key 25 prevents further rotation of the inner tube connector 26 and the inner tube body 29, ensuring their relative positions are fixed. The pressure cap 23 is threaded onto the central shaft 22. The pressure cap 23 may be provided with an annular groove to avoid the key 25, so that the rotation of the pressure cap 23 is not affected by the key 25, thereby axially pressing the pressure cap 23 against the inner tube body 29, further ensuring the connection stability between the inner tube body 29 and the central shaft 22.

[0040] In one embodiment, a core-protecting water-blocking mechanism is also included. This mechanism includes a one-way valve 28 and two non-communicating jet channels and drainage channels axially formed along the central axis 22. The inlet of the jet channel is away from the drill bit 36 ​​and faces the direction of the drilling fluid flow. The inlet of the drainage channel is close to the drill bit 36, and a one-way valve 28 is installed at the inlet of the drainage channel, ensuring that the drilling fluid entering the inner tube body 29 can only enter the drainage channel in one direction. A jet hole 20 communicating with the jet channel is also provided on the central axis 22, with the jet hole 20 angled towards the drill bit 36. A drainage hole 21 communicating with the drainage channel is also provided on the central axis 22, with the drainage hole 21 angled away from the drill bit 36. After the high-pressure drilling fluid pumped in by the mud pump enters the jet channel, it flows out through the jet hole 20. A high-pressure jet is formed in the cavity between the central shaft 22 and the outer tube, which causes the cavity pressure to decrease. This creates a suction effect on the drilling fluid flowing out of the drain hole 21, promoting the drainage of drilling fluid in the inner tube body 29. This further reduces the resistance of the core entering the inner tube body 29 and prevents the drilling fluid from eroding the core.

[0041] In one embodiment, a bottom nozzle 35 is also provided on the drill bit 36. The bottom nozzle 35 axially penetrates the drill bit 36, and the drilling fluid can be discharged through the bottom nozzle 35, thereby reducing the erosion of the core by the drilling fluid at the first moment when the bottom layer is drilled.

[0042] In one embodiment, the one-way valve 28 includes a valve ball 27 located at the outlet of the one-way valve 28. During drilling, the valve ball 27 is pushed up by the drilling fluid in the inner tube body 29, thereby opening the one-way valve 28. The drilling fluid that enters the drainage channel is discharged through the drainage hole 21.

[0043] In one embodiment, a suspension mechanism is also included. The suspension mechanism includes an upper suspension connector 2 and a seat ring 7. The outer tube includes an outer tube body 30, an upper connector 5, and an upper tube body. The upper connector 5 is used to connect the outer tube body 30 and the upper tube body. The upper tube body, the upper connector 5, and the outer tube body 30 are connected sequentially from top to bottom. The seat ring 7 is connected to the upper connector 5. The upper suspension connector 2 is connected to the upper tube body via a second ball clamp structure. The upper suspension connector 2 is connected to the lower suspension connector 13. The upper suspension connector 2 has a contact surface that connects with the seat ring 7. The seat ring 7 is used to limit the axial position of the upper suspension connector 2. In this example, the contact surface has a certain bevel angle to increase the contact area, ensure that the suspension is firm and reliable, and maintain a suitable gap between the core claw 34 and the inner step of the drill bit 36.

[0044] In one embodiment, the second ball-locking structure includes a female spearhead 1, a spring seat 8, a third spring 6, and a second suspended steel ball 3. The upper suspension connector 2 has a radially penetrating second ball hole through which the second suspended steel ball 3 can pass. A second one-way ball-locking groove is provided on the outer diameter side of the female spearhead 1, allowing the second suspended steel ball 3 to enter and exit from one axial side, while restricting its movement on the other axial side. A second two-way ball-locking groove 4 is provided on the inner diameter side of the upper tube in the outer tube, allowing the second suspended steel ball 3 to enter and exit only radially in the second two-way ball-locking groove 4, restricting its movement on both axial sides. One end of the third spring 6 abuts against the inner flange of the upper suspension joint 2, and the other end of the third spring 6 abuts against the outer flange of the spring seat 8. Thus, in the snap-fit ​​state, the third spring 6 provides a downward pushing force to the female spearhead 1 through the spring seat 8, causing the second one-way snap-fit ​​ball groove to be misaligned with the second ball hole. At this time, the female spearhead 1 restricts the second suspension steel ball 3 within the second ball hole and the second two-way snap-fit ​​ball groove 4. When the snap-fit ​​is released, the female spearhead 1 moves away from the drill bit 36, and the second suspension steel ball 3 can enter the second one-way snap-fit ​​ball groove from the second two-way snap-fit ​​ball groove 4, causing the upper suspension joint 2 to detach from the upper tube body.

[0045] By using a second ball clamp structure instead of the traditional spring clamp positioning mechanism, the mother retrieval spearhead 1 is adjusted before the drill bit is lowered so that the second suspension steel ball 3 exits the second ball hole of the upper suspension joint 2. When the drill bit is lowered into place, under the action of the third spring 6, the second suspension steel ball 3 enters the second bidirectional clamping ball groove 4 to achieve positioning and auxiliary suspension, and restrict the axial movement of the inner tube assembly.

[0046] like Figures 1-5As shown, the present invention also provides a wireline coring tool, including the inner tube assembly as described above, and a retrieval device. The retrieval device includes a fixed joint 206, a male retrieval spearhead 211, and a fourth spring 210. The male retrieval spearhead 211 is hinged to the fixed joint 206 via a retrieval hook positioning pin 207. The male retrieval spearhead 211 can be arranged around a central column. The central column is connected to the fourth spring 210 via a spring positioning pin 209. The fourth spring 210 abuts against or is connected to the male retrieval spearhead 211. The fourth spring 210 can be a torsion spring, which can keep the male retrieval spearhead 211 extended outward. When the retrieval device is used to retrieve the inner tube assembly, the wire rope 201 suspends the retrieval device and places it into the drill string. Relying on inertia and gravity, the male retrieval spearhead 211 is locked to the upper end of the female retrieval spearhead 1. Specifically, after the male retrieval spearhead 211 is forced to retract inward, it can penetrate into the female retrieval spearhead 1 and unfold to reset outward under the action of the fourth spring 210. The claws of the male retrieval spearhead 211 can prevent the male retrieval spearhead 211 from disengaging from the female retrieval spearhead 1, thereby realizing the connection between the male retrieval spearhead 211 and the female retrieval spearhead 1. Then, the male retrieval spearhead 211 of the retrieval device is lifted upward under the pulling action of the wire rope 201, which drives the spring seat 8 to move and compress the third spring 6, causing the position of the lower end of the female retrieval spearhead 1 corresponding to the second suspension steel ball 3 to change. The second suspension steel ball 3 rolls to release the ball lock, thereby lifting the inner tube assembly.

[0047] In one embodiment, a weighted tube 204 is connected to the upper end of the fixed joint 206 to provide pressure, facilitating the downward entry of the male retrieval spearhead 211 into the female retrieval spearhead 1. A guide head 212 may be connected to the lower end of the fixed joint 206. The lower end of the guide head 212 is provided with an inclined surface or a conical surface, which can reduce the jamming when the retrieval device enters the female retrieval spearhead 1.

[0048] In one embodiment, the retrieval device further includes a safety release mechanism, which includes a retaining ring 205, a release ring 208, and a release tube 301. The retaining ring 205 is connected to the release ring 208, and the two are fitted together at the fixed joint 206. The lower end face of the release ring 208 is provided with an inner inverted conical surface, and the male retrieval spearhead 211 is provided with an inclined surface that cooperates with the inner inverted conical surface. When release is required, the release tube 301 is inserted into the wire rope 201 along the spiral opening 302. The release tube 301 moves downward and impacts the retaining ring 205. Under the interaction of the inner inverted conical surface of the release ring 208 and the inclined surface of the male retrieval spearhead 211, the male retrieval spearhead 211 retracts inward, thereby causing the retrieval device to detach from the inner tube assembly.

[0049] In one embodiment, a flared head 202 is connected to the top of the weighting tube 204, and the flared head 202 is connected to the wire rope 201. The flared head 202 and the weighting tube 204 are connected by a safety pin 203, which can be broken under a certain tension. If the release tube 301 cannot be released smoothly, the wire rope 201 can be successfully retrieved by breaking the safety pin 203.

[0050] The working principle of this invention is as follows:

[0051] After the inner tube assembly is lowered, the upper suspension connector 2 contacts the seat ring 7, indicating that it has been deployed. At the same time, the second suspension steel ball 3 enters the second bidirectional locking ball groove 4 to complete positioning. During drilling, the second suspension steel ball 3 connects the upper tube body and the upper suspension connector 2 to limit axial displacement, preventing the core from pushing upwards into the inner tube body 29 and causing it to move upwards. However, it can also be successfully unjawed during retrieval. During retrieval, the female retrieval spearhead 1 is lifted. The female retrieval spearhead 1 drives the spring seat 8, compressing the third spring 6 and generating an upward displacement. After the third spring 6 is compressed to a certain extent, the second unidirectional locking ball groove of the female retrieval spearhead 1 coincides with the second suspension steel ball 3, allowing the second suspension steel ball 3 to be released. The connection between the upper tube body and the upper suspension connector 2 is released, the ball-jaw function is disabled, and the drill string can be retrieved smoothly. After being retrieved from the ground, the tension of the steel wire rope 201 is released, and the energy of the third spring 6 is also released, squeezing the second suspended steel ball 3 out of the second one-way clamping ball groove of the mother spearhead 1.

[0052] The ball clamp suspension at the first suspension steel ball 11 is an auxiliary mechanism for ball dropping and clamping, used to connect the lower suspension joint 13 and the suspension ring 15. The first spring 14 is used to release the clamp, and the first spring 14 returns to its original position after the energy is released. After drilling is completed, the sealing steel ball 10 is dropped, and the sliding sleeve 12 moves downward under the action of pump pressure, compressing the first spring 14. Subsequently, the first one-way clamping ball groove on the sliding sleeve 12 coincides with the first suspension steel ball 11, and the first suspension steel ball 11 is released. The connection between the lower suspension joint 13 and the suspension ring 15 is released, and the ball clamping function is disabled. The suspension ring 15 moves downward under the action of liquid column pressure, driving the central shaft 22 and the structure connected to it to move downward, forcing the core claw 34 to contract under the obstruction of the inclined surface of the drill bit 36, completing the core retrieval. After moving a certain distance, the pressure relief hole 9 on the lower suspension joint 13 opens, the drilling fluid can circulate, and the pressure is released. After the pump stops, the energy stored in the first spring 14 is released, causing the sliding sleeve 12 to move upward, and the first suspension steel ball 11 returns to its original position.

[0053] The bearing cavity 18 houses the upper bearing 16, the second spring 17, and the lower bearing 19, ensuring that the central shaft 22 remains circumferentially stationary relative to the upper structure during drilling. Keyways 24 are provided on the central shaft 22 and the inner tube connector 26. The pressure cap 23 and the inner tube connector 26 are connected to the central shaft 22 via threads. A key 25 is inserted into the keyway 24 to fix the central shaft 22 and the inner tube connector 26, ensuring their synchronous movement. The lower end face of the pressure cap 23 and the upper end face of the inner tube connector 26 are pressed together via threads to fix the key 25 within the cavity of the pressure cap 23, preventing it from falling out. The inner tube connector 26 is threadedly connected to the inner tube body 29. The inner tube body 29 and other mechanisms connected to its lower end move synchronously with the central shaft 22. This ensures that the inner tube body 29 does not rotate during drilling, reducing friction between the inner wall of the inner tube body 29 and the core.

[0054] During drilling, the drilling fluid pumped in enters the jet channel and flows out through the jet hole 20, entering the annular gap between the inner tube body 29 and the outer tube body 30, and finally flows out through the bottom nozzle 35 of the drill bit 36 ​​into the annulus between the bottom layer and the drill pipe. The drilling fluid in the inner tube body 29 enters the drainage channel of the central shaft 22 through the one-way valve 28 and is discharged through the drainage hole 21. The high-pressure drilling fluid pumped in by the mud pump flows out through the jet hole 20, forming a high-pressure jet in the cavity between the central shaft 22 and the outer tube body 30, causing a decrease in cavity pressure. This creates a suction effect on the drilling fluid flowing out of the drainage hole 21, promoting the drainage of drilling fluid in the inner tube body 29, further reducing the resistance of the core entering the inner tube body 29 and preventing drilling fluid erosion.

[0055] The retrieval device uses a fourth spring 210 to retract and extend the male retrieval spearhead 211 to engage and disengage the female retrieval spearhead 1. The weighting tube 204 provides additional weight. A bevel is provided at the lower end of the guide head 212 to reduce jamming when the retrieval device enters the female retrieval spearhead 1. The safety release mechanism uses a release tube 301. When release is needed, the release tube 301 is inserted into the wire rope 201 along the spiral opening 302, impacting the impact ring 205. The interaction between the bevel of the release ring 208 and the bevel of the male retrieval spearhead 211 causes the retrieval device to detach from the inner tube assembly. The retrieval head 202 and the weighting tube 204 are connected by a safety pin 203. The safety pin 203 can break under a certain tension. If the release tube 301 cannot release the jam smoothly, breaking the safety pin 203 allows for the successful retrieval of the wire rope 201.

[0056] The core extraction process of this invention is as follows:

[0057] Before drilling, carefully inspect the outer and inner tubes (29). If any problems are found, correct or replace them promptly. Clean all parts of the drill string and apply an appropriate amount of lubricating oil to ensure smooth drill string movement.

[0058] When lowering the drill string, the pump is turned on to pressurize the drilling rig, and the operator closely monitors the changes in the pressure gauge readings of the mud pump. When the pump pressure rises and then drops rapidly, and a striking sound can be heard within 1000m of the hole depth, it indicates that the inner tube assembly has been lowered into place and drilling can begin.

[0059] At the end of drilling, insert the sealing steel ball 10 into the drill string, calculate the descent time of the sealing steel ball 10, and start the pump to pressurize after the sealing steel ball 10 has reached its position. When the pressure gauge pressure rises to a certain value and then suddenly drops, it indicates that the ball has been pressurized and is stuck in place. Then, shut down the mud pump and begin the retrieval operation.

[0060] The retrieval tool is lowered to retrieve the inner tube assembly. After retrieving the inner tube assembly, the core sample is promptly removed and properly preserved. Lubricating oil is added to each bearing to ensure normal operation. Then, another inner tube assembly is quickly lowered for the next drilling and coring operation, shortening the auxiliary drilling time.

[0061] Throughout the drilling process, drilling parameters such as drilling pressure, rotation speed, and pump flow rate are adjusted appropriately based on different formation conditions and drilling progress to ensure drilling efficiency and core quality. Simultaneously, the drilling tools are regularly maintained and serviced, with checks on the wear of various components and timely replacement of vulnerable parts to ensure long-term stable operation.

[0062] Specific examples have been used to illustrate the principles and implementation methods of this invention. The descriptions of the above embodiments are only for the purpose of helping to understand the method and core ideas of this invention. Furthermore, those skilled in the art will recognize that, based on the ideas of this invention, there will be changes in the specific implementation methods and application scope. Therefore, the content of this specification should not be construed as a limitation of this invention.

Claims

1. An inner tube assembly, characterized in that, include: An outer tube, the end of which is connected to a drill bit; Inner tube body, which is sleeved inside the outer tube; A core retrieval mechanism, comprising a core claw connected to the inner tube body, wherein after the inner tube body moves toward the drill bit, the core claw retracts toward the inner diameter side due to the contact of the drill bit; And a ball-throwing clamping mechanism, the ball-throwing clamping mechanism including a sliding sleeve, a suspension ring and a lower suspension joint, the sliding sleeve being sleeved on the inner diameter side of the suspension ring, the suspension ring being connected to the lower suspension joint through a first ball-throwing clamping structure, the suspension ring being connected to the inner tube body, and the lower suspension joint being connected to the outer tube; The first ball-clamping structure includes a first suspended steel ball and a first spring. The suspension ring has a radially penetrating first ball hole. The outer diameter side of the sliding sleeve is provided with a first one-way ball-clamping groove, and the inner diameter side of the lower suspension joint is provided with a first two-way ball-clamping groove. One end of the first spring abuts against the sliding sleeve, and the other end of the first spring abuts against the inner flange of the suspension ring. When the sliding sleeve moves toward the drill bit, the first suspended steel ball can enter the first one-way ball-clamping groove from the first two-way ball-clamping groove, causing the suspension ring to disengage from the lower suspension joint.

2. The inner tube assembly according to claim 1, characterized in that: The core retrieval mechanism also includes a core claw seat, which is connected to the inner tube body via a lower connector. The free end of the core claw has multiple circumferentially distributed lobes, which can deform towards the inner diameter side.

3. The inner tube assembly according to claim 1, characterized in that: It also includes a buffer mechanism, which includes a central shaft and a second spring. The central shaft is provided with a shoulder. One end of the second spring abuts against the suspension ring, and the other end of the second spring abuts against the shoulder. The end of the central shaft away from the suspension ring is connected to the inner tube body.

4. The inner tube assembly according to claim 3, characterized in that: It also includes a single-action mechanism, which includes a rotating component and an anti-rotation component. The rotating component includes an upper bearing, a lower bearing, and a bearing cavity. The bearing cavity is sleeved on the outer diameter side of the central shaft and connected to the suspension ring. The upper bearing and the lower bearing are both located between the central shaft and the bearing cavity. In the axial direction, the upper bearing is located between the second spring and the suspension ring, and the lower bearing is located between the shaft shoulder and the bearing cavity. The anti-rotation component is connected between the central shaft and the inner tube body.

5. The inner tube assembly according to claim 4, characterized in that: The anti-rotation assembly includes an inner tube connector, a key, and a pressure cap. The inner diameter side of the inner tube connector is threaded to the central shaft, and the outer diameter side of the inner tube connector is threaded to the inner tube body. The central shaft and the inner tube connector are provided with a keyway for inserting the key. The pressure cap is threaded to the central shaft and is used to axially press the inner tube body.

6. The inner tube assembly according to claim 3, characterized in that: It also includes a core-protecting water-blocking mechanism, which includes a one-way valve and non-communicating jet channels and drainage channels opened axially along the central axis. The inlet of the jet channel is away from the drill bit, and the inlet of the drainage channel is close to the drill bit. The one-way valve is installed at the inlet of the drainage channel. A jet hole communicating with the jet channel is also opened on the central axis, and the jet hole is obliquely oriented towards the drill bit. A drainage hole communicating with the drainage channel is also opened on the central axis, and the drainage hole is obliquely oriented away from the drill bit.

7. The inner tube assembly according to claim 1, characterized in that: It also includes a suspension mechanism, which includes an upper suspension joint and a seat ring. The seat ring is connected to the outer tube, and the upper suspension joint is connected to the outer tube through a second ball joint structure. The upper suspension joint is connected to the lower suspension joint, and the upper suspension joint has a contact surface that connects with the seat ring. The seat ring is used to limit the axial position of the upper suspension joint.

8. The inner tube assembly according to claim 7, characterized in that: The second ball-clamping structure includes a female retrieval spearhead, a spring seat, a third spring, and a second suspension steel ball. The upper suspension joint has a radially penetrating second ball hole. The outer diameter side of the female retrieval spearhead is provided with a second one-way ball-clamping groove, and the inner diameter side of the outer tube is provided with a second two-way ball-clamping groove. One end of the third spring abuts against the inner flange of the upper suspension joint, and the other end of the third spring abuts against the outer flange of the spring seat. When the female retrieval spearhead moves away from the drill bit, the second suspension steel ball can enter the second one-way ball-clamping groove from the second two-way ball-clamping groove, causing the upper suspension joint to disengage from the outer tube.

9. A wireline coring tool, characterized in that: The device includes the inner tube assembly as described in claim 8, and also includes a retrieval device. The retrieval device includes a fixed joint, a male retrieval spearhead, and a fourth spring. The male retrieval spearhead is hinged to the fixed joint and connected to the fourth spring. The male retrieval spearhead can penetrate into the female retrieval spearhead and, after being reset by the action of the fourth spring, achieves the connection between the male retrieval spearhead and the female retrieval spearhead.

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