A locking device suitable for use in cased hole drilling

Abstract

This invention discloses a locking device suitable for casing drilling, comprising a locking outer sleeve and an inner core. The bottom of the locking outer sleeve is connected to a casing string. The top of the inner core is fitted with a hollow feed shaft for pushing a locking block into a limiting annular groove. The feed shaft has a limiting groove extending axially at the position corresponding to the limiting pin. The limiting pin abuts against the inner walls of the upper and lower ends of the limiting groove when the feed shaft is pressed down or moved up. The inner core is also provided with a shearing pin to fix the feed shaft after it is inserted into place. The bottom of the inner core is fitted with a hollow connecting shaft, which is connected to both the inner core and the feed shaft. The bottom of the connecting shaft is connected to the downhole drilling tool, which is located in the casing string. The locking device connects the casing string and the downhole drilling tool. After drilling operations are completed, the locking device and the downhole drilling tool are retrieved, leaving the casing string at the bottom of the well. This combines the drilling and casing installation processes into one, improving drilling efficiency and reducing the occurrence of safety accidents.

Description

Technical Field

[0001] This invention relates to the field of drilling equipment technology, and in particular to a locking device suitable for casing drilling. Background Technology

[0002] In the drilling field, the traditional drilling method is to drill a hole first and then run casing for wall protection. This method has certain safety issues. During, after, or during the tripping and casing running process, the open hole may collapse, or the casing may get stuck and fail to be run in place, wasting a lot of time, especially in deep wells, horizontal wells, and offshore operations.

[0003] There are two existing solutions for casing run-down obstruction. The first solution mainly addresses the issue through process control: 1) Controlling the obstruction tonnage. When the casing string encounters obstruction, it is crucial to avoid forcing it down; maintain a suitable obstruction tonnage. 2) Adopting an appropriate lowering speed. Too fast a lowering speed makes it difficult to react promptly when the casing string encounters obstruction, while too slow a lowering speed affects operational efficiency. 3) Immediately lifting the movable casing string upon encountering obstruction to prevent casing jamming. Calculate the maximum lifting tonnage in advance based on the drilling rig's lifting capacity and the tensile strength of the casing string's weakest point, and lift the string to the maximum tonnage as quickly as possible to avoid complex situations. If, after encountering obstruction, the casing cannot be pushed down or lifted up, on-site cementing or casing cutting is necessary, leading to complex downhole accidents. However, this still cannot effectively prevent downhole problems such as casing drilling jamming.

[0004] The second option is power-guided casing technology (a power-guided casing device for inclined boreholes in weak formations, authorization announcement number: CN209228305U). After drilling is completed, a screw and drill bit are connected before the casing. During casing running, the pump is turned on, and the screw drives the drill bit to rotate, assisting in casing running. However, because casing drilling is a single run of drilling and casing running, while power-guided casing running requires two runs, it inevitably leads to longer drilling time and increased operating costs. Summary of the Invention

[0005] The purpose of this invention is to provide a locking device suitable for casing drilling to solve the problems existing in the prior art. The locking device connects the casing string to the downhole drilling tool. After the drilling operation is completed, the locking device and the downhole drilling tool are retrieved, leaving the casing string at the bottom of the well. The drilling and casing running processes are combined into one and completed in one go, which improves drilling efficiency and reduces the occurrence of safety accidents.

[0006] To achieve the above objectives, the present invention provides the following solution: The present invention provides a locking device suitable for casing drilling, comprising a locking outer sleeve with a straight cylindrical structure and an inner core inserted inside it. The bottom of the locking outer sleeve is connected to a casing string. The inner circumferential wall of the locking outer sleeve is provided with a limiting annular groove coaxial with it and a plurality of limiting pins located above the limiting annular groove. The inner core is provided with guide through holes coaxial with the limiting annular groove at equal intervals along the circumference. A locking block capable of self-resetting and disengaging from the limiting annular groove is movably provided in the guide through hole.

[0007] The inner core has a hollow feed shaft inserted at its top for pushing the locking block into the limiting annular groove. The feed shaft has a limiting groove extending axially at the position corresponding to the limiting pin. The limiting pin abuts against the inner walls of the upper and lower ends of the limiting groove when the feed shaft is pressed down or moved up. The inner core has a shearing pin to fix the feed shaft after it is inserted into place. The bottom of the inner core has a hollow connecting shaft inserted. The connecting shaft is connected to both the inner core and the feed shaft. The bottom of the connecting shaft is connected to a downhole drilling tool, which extends out of the casing string.

[0008] Preferably, a reset groove is provided on the side of the card block away from the feed shaft, penetrating its outer circumference. A stop bar extending from both sides of the card block is provided in the reset groove. Both ends of the stop bar are fixed to the inner core. A first reset spring for driving the card block to reset is provided between the stop bar and the bottom of the reset groove.

[0009] Preferably, the feed shaft includes a wide section for pushing the locking block to move and a narrow section connected to the bottom end of the wide section. The outer peripheral wall of the wide section abuts against the inner end of the guide through hole, and the narrow section and the inner end of the guide through hole have a gap for the locking block to disengage from the limiting annular groove.

[0010] Preferably, the inner peripheral wall of the inner core is provided with an annular step for the narrow segment to abut against the end of the narrow segment when it is inserted into the inner core.

[0011] Preferably, the inner core extends beyond the top of the locking device outer sleeve, and the shear pin is installed at the position where the inner core extends beyond the locking device outer sleeve.

[0012] Preferably, the outer peripheral wall of the inner core is further provided with a plurality of lower limit blocks located below the locking block. Each lower limit block is equally spaced along the circumference of the inner core. The top of the lower limit block is rotatably connected to the inner core. A second return spring is provided between the bottom of the lower limit block and the inner core to push the lower limit block toward the locking sleeve. The locking sleeve is provided with an annular groove at the position corresponding to the lower limit block. The top of the annular groove has a chamfer to facilitate the upper sliding of the lower limit block. The bottom of the annular groove has a limiting step for engaging the bottom of the lower limit block.

[0013] Preferably, the outer peripheral wall of the inner core is provided with a lower limit block mounting groove that fits into the lower limit block. A first retaining ring is provided between the top of the lower limit block mounting groove and the locking sleeve to prevent the top of the lower limit block from dislodging from the lower limit block mounting groove. A second retaining ring is provided between the bottom of the lower limit block mounting groove and the locking sleeve to prevent the bottom of the lower limit block from moving downward.

[0014] Preferably, the outer peripheral wall of the inner core is further provided with a plurality of torque transmission block mounting slots located below the lower limit block. Each torque transmission block mounting slot is equally spaced along the axial direction of the inner core. Each torque transmission block mounting slot is provided with a torque transmission block and a third return spring for pushing the torque transmission block toward the locking device outer sleeve as a whole. The locking device outer sleeve is provided with a plurality of torque transmission grooves corresponding one-to-one with each torque transmission block. After the inner core moves into place, each torque transmission block is tightly engaged in each torque transmission groove.

[0015] Preferably, the bottom of the torque transmission block mounting groove is provided with a third retaining ring for limiting the bottom of the torque transmission block from disengaging from the torque transmission block mounting groove, and the second retaining ring is located at the top of the torque transmission block mounting groove and abuts against the top of the torque transmission block.

[0016] Preferably, both ends of the locking device outer sleeve are provided with connecting buckles for connecting the sleeve string. The connecting buckle located at the top is detachably connected to an installation fixture that is coaxially arranged with the locking device outer sleeve and has a cylindrical structure. The inner peripheral wall of the installation fixture is smoothly connected to the inner peripheral wall of the locking device outer sleeve.

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

[0018] First, connect the bottom end of the locking device outer sleeve to the casing string. Insert the feed shaft into the inner core and install the limiting pin, which connects to the inner core and simultaneously presses against the corresponding limiting groove of the feed shaft. After connecting the inner core to the downhole drilling tools via the connecting shaft, lower it into the locking device outer sleeve and casing string. During the descent, the locking block moves with the inner core to the position of the upper limiting annular groove on the locking device outer sleeve. Press the feed shaft down to its lowest point, and the feed shaft pushes the locking block into the limiting annular groove, completing the connection between the inner core and the locking device outer sleeve. The positioning is then completed by installing shear pins to fix the inner core and the feed shaft. After drilling is completed, a retrieval tool is lowered into the casing string. The retrieval tool is connected to the feed shaft in the downhole drill string and lifted up. The shear pins are cut off under tension. The feed shaft, through the limit pin, drives the inner core and the bottom hole drill string to be retrieved to the surface. The casing drilling operation is completed, leaving the casing string at the bottom of the well. The drilling and casing lowering processes are combined into one, completed in one go, which improves drilling efficiency and reduces the occurrence of safety accidents.

[0019] Secondly, a reset groove is provided on the side of the locking block away from the feed shaft, penetrating its outer circumference. A stop bar extending from both sides of the locking block is inserted into the reset groove, with both ends of the stop bar fixed to the inner core. A first reset spring for driving the locking block to reset is provided between the stop bar and the bottom of the reset groove. During use, by installing the stop bar in the reset groove and fixing it to the inner core, a reaction force structure as the first reset spring is formed. The stop bar moves circumferentially in the reset groove, and the feed shaft pushes the locking block to overcome the elastic force of the first reset spring. The structure at the opening of the reset groove passes over the stop bar and abuts against the limiting ring groove, completing the positioning function of the inner core and the locking device outer sleeve, preventing the inner core from moving up or down during drilling, which would prevent the drilling work from being completed effectively.

[0020] Third, the feeding shaft includes a wide section for pushing the locking block to move and a narrow section connected to the bottom of the wide section. The outer peripheral wall of the wide section abuts against the inner end of the guide through hole. The narrow section and the inner end of the guide through hole have a gap for the locking block to disengage from the limiting ring groove. During the pressing process of the feeding shaft, after the narrow section passes the guide through hole, the wide section gradually approaches the guide through hole and pushes the locking block, completing the engagement between the locking block and the limiting ring groove. During the upward movement of the feeding shaft, after the wide section passes the guide through hole, the narrow end gradually approaches the guide through hole, so that the locking block is no longer pressed by the wide section. Then, under the action of the first return spring, it moves inward. A reasonable gap is provided between the narrow section and the guide through hole, so that the locking block can fully disengage from the limiting ring groove, avoiding affecting the upward movement of the inner core, while preventing the locking block from falling out of the guide through hole.

[0021] Fourth, an annular step is provided on the inner circumferential wall of the inner core for the narrow section to abut against the end of the narrow section when it is inserted into the inner core. On the one hand, the abutment between the narrow section and the annular step completes the positioning of the feed shaft in the inner core. On the other hand, it completes the limiting function of the feed shaft, so that it can keep its position unchanged and will not move down relative to the inner core as drilling work progresses, thus affecting the positioning of the downhole drilling tools. Attached Figure Description

[0022] 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.

[0023] Figure 1 This is a schematic diagram of the overall structure of the present invention;

[0024] Figure 2 This is a schematic diagram of the core structure of the present invention;

[0025] Figure 3 This is a schematic diagram of the card block structure of the present invention;

[0026] Among them, 1-locker outer sleeve; 2-feed shaft; 3-inner core; 4-shearing pin; 5-limiting pin; 6-block; 6-1-stop bar; 7-first retaining ring; 8-lower limit block; 9-second retaining ring; 10-torsion transmission block; 11-third retaining ring; 12-connecting shaft; 13-installation fixture; 14-shearing hole; 15-guide through hole; 16-lower limit block mounting groove; 17-torsion transmission block mounting groove; 18-reset groove. Detailed Implementation

[0027] 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.

[0028] The purpose of this invention is to provide a locking device suitable for casing drilling to solve the problems existing in the prior art. The locking device connects the casing string and the drill string. After the drilling operation is completed, the locking device and the drill string are retrieved, leaving the casing string at the bottom of the well. The drilling and casing running processes are combined into one and completed in one go, which improves drilling efficiency and reduces the occurrence of safety accidents.

[0029] 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.

[0030] like Figures 1 to 3 As shown, this embodiment provides a locking device suitable for casing drilling, including a locking outer sleeve 1 with a straight cylindrical structure and an inner core 3 inserted inside it. Preferably, the upper and lower ends of the locking outer sleeve 1 are designed with sealing surfaces, and the upper and lower ends of the inner core 3 are provided with sealing grooves that match the sealing surfaces, forming a seal between the two. This avoids the subsequent expansion and contraction of the locking block 6, lower limit block 8, and transmission torque block 10 being affected by mud, making the feasibility and reliability of the recovery operation higher. The bottom of the locking outer sleeve 1 is connected to the casing string. The inner peripheral wall of the locking outer sleeve 1 is provided with a limit ring groove coaxial with it and a number of limit pins 5 located above the limit ring groove. The inner core 3 is provided with guide through holes 15 at equal intervals along the circumference, which are coaxial with the limit ring groove. A locking block 6 that can self-reset and disengage from the limit ring groove is movably provided in the guide through hole 15. Preferably, the limit ring groove corresponding to the locking block 6 also has a chamfer to facilitate the upward movement of the locking block 6.

[0031] The top of the inner core 3 is fitted with a hollow feeding shaft 2 for pushing the locking block 6 into the limiting ring groove. Preferably, the feeding shaft 2 can be first inserted into the inner core 3, and the locking block 6 can be inserted into the guide through hole 15 on the inner core 3. The feeding shaft 2 can prevent the locking block 6 from falling into the inner core 3. Then, the feeding shaft 2 is pressed down to complete the locking of the locking block 6 and the limiting ring groove. Furthermore, the feed shaft 2 is provided with a limiting groove extending axially at the position corresponding to the limiting pin 5. The limiting pin 5 abuts against the inner walls of the upper and lower ends of the limiting groove when the feed shaft 2 is pressed down or moved up. The inner core 3 is provided with a shearing pin 4 to fix the feed shaft 2 after it is inserted into place. Preferably, the feed shaft 2 and the inner core 3 are provided with corresponding shearing holes 14, and the shearing pin 4 is inserted into the shearing holes 14 of both. A hollow connecting shaft 12 is inserted into the bottom end of the inner core 3. The connecting shaft 12 is connected to both the inner core 3 and the feed shaft 2. The bottom of the connecting shaft 12 is connected to the downhole drilling tool, which is located in the casing string. Preferably, the connecting shaft 12 is a variable diameter structure that is wide in the middle and narrow at both ends. The variable diameter structure is connected to the inner core 3 through the drill pipe buckle.

[0032] Preferably, the upper part of the feed shaft is designed with a hexagonal structure so that the feed shaft will not rotate when it moves up and down axially. The feed shaft has a hexagonal structure to limit its own axial movement. The inner circumferential wall of the inner core is provided with a hexagonal hole inner wall for the axial movement of the hexagonal structure on the feed shaft. The outer wall of the hexagonal structure abuts against the inner wall of the hexagonal hole of the inner core. There are shearing holes 14 for shearing pins 4 to be inserted on the hexagonal structure and the inner wall of the hexagonal hole. The shearing hole 14 is composed of two holes on the hexagonal structure and the inner wall of the hexagonal hole.

[0033] Connect the bottom end of the locking device outer sleeve 1 to the casing string, insert the feed shaft 2 into the inner core 3, and install the limiting pin 5. The limiting pin 5 is connected to the inner core 3 and simultaneously presses against the corresponding limiting groove of the feed shaft 2. After connecting the inner core 3 to the downhole drilling tool via the connecting shaft 12, lower it into the locking device outer sleeve 1 and the casing string. During the descent, the locking block 6 moves with the inner core 3 to the position of the upper limiting annular groove of the locking device outer sleeve 1. Press the feed shaft 2 down to the lowest point, and the feed shaft 2 pushes the locking block 6 into the limiting annular groove, completing the locking of the inner core 3 and the locking device outer sleeve 1. The positioning between the inner core 3 and the feed shaft 2 is then completed by installing the shear pin 4. After drilling is completed, the drill string above ground is removed, and a retrieval tool is lowered into the casing string. The retrieval tool is connected to the feed shaft 2 downhole and lifted. The shear pin 4 is sheared under tension. The feed shaft 2, through the limiting pin 5, drives the inner core 3 and the bottom hole drill string to be retrieved to the surface. The casing drilling operation is completed, leaving the casing string at the bottom of the well. The drilling and casing lowering processes are combined into one, completed in one go, improving drilling efficiency and reducing the occurrence of safety accidents. Preferably, since the limiting pin 5 abuts against the inner walls of the limiting groove at both ends when the feed shaft 2 is pressed down or moved up, the shear pin 4 can be sheared during the upward movement of the feed shaft 2, causing a relative displacement between the limiting groove and the limiting pin 5, thereby allowing the feed shaft 2 to carry the inner core 3 upward.

[0034] The card block 6 has a reset groove 18 extending through its outer circumference on the side away from the feed shaft 2. A stop bar extending from both sides of the card block 6 is inserted into the reset groove 18. Both ends of the stop bar are fixed to the inner core 3. A first reset spring for driving the card block 6 to reset is provided between the stop bar and the bottom of the reset groove 18. Preferably, the first reset spring is fixed in the groove of the card block 6 using grease with high viscosity, and then the stop bar 6-1 is installed. The stop bar 6-1 is connected and fixed to the inner core 3 by bolts. The locking block 6 is limited by the stop bar 6-1 and can freely extend and retract under the action of the first return spring. During use, by installing the stop bar in the return groove 18 and fixing it to the inner core 3, a reaction force structure for the first return spring is formed. The stop bar moves circumferentially in the return groove 18, and the feed shaft 2 pushes the locking block 6 to overcome the elastic force of the first return spring. The structure at the opening of the return groove 18 passes the stop bar and abuts in the limiting ring groove, completing the positioning function of the inner core 3 and the locking sleeve 1, realizing the upper and lower limit, and preventing the inner core 3 from moving up or down during drilling, which would prevent the drilling work from being completed effectively. If the inner drill bit moves down, it will cause the inner drill bit to fall to the bottom of the well, causing a downhole accident. If the inner drill bit moves up, it will cause the drill bit to be unable to advance and drilling will be impossible. Therefore, the locking block 6 is needed to limit the upper and lower displacement.

[0035] Furthermore, the feeding shaft 2 includes a wide section for pushing the locking block 6 to move and a narrow section connected to the bottom end of the wide section. The outer peripheral wall of the wide section abuts against the inner end of the guide through hole 15. The narrow section and the inner end of the guide through hole 15 have a gap for the locking block 6 to disengage from the limiting ring groove. During the pressing process of the feeding shaft 2, after the narrow section passes the guide through hole 15, the wide section gradually approaches the guide through hole 15 and pushes the locking block 6, completing the engagement between the locking block 6 and the limiting ring groove. During the upward movement of the feeding shaft 2, after the wide section passes the guide through hole 15, the narrow end gradually approaches the guide through hole 15, so that the locking block 6 is no longer pressed by the wide section. The locking block 6 loses the lateral pushing force of the wide section and retracts into the inner core 3 under the action of the first return spring. There is a sufficient gap between the narrow section and the guide through hole 15 so that the locking block 6 can fully disengage from the limiting ring groove and avoid affecting the upward movement of the inner core 3. When the feed shaft 2 is fixed to the inner core 3 by the shear pin 4, the wide section of the feed shaft 2 pushes against the locking block 6, extends out of the inner core 3, and pushes against the limiting ring groove of the locking device outer sleeve 1.

[0036] Moreover, both the wide and narrow sections of the feed shaft 2 have sealing grooves that match the sealing surface of the inner wall of the guide through hole. When the feed shaft 2 is installed in place, the annular space between the feed shaft 2 and the inner core 3 forms a seal. When slurry is passed through, the slurry flows out from the through hole of the feed shaft 2 and enters the inner core 3 and the middle hole of the connecting shaft 12 in sequence, without entering the locking block 6 and hindering the contraction of the locking block 6.

[0037] Preferably, the inner peripheral wall of the inner core 3 is provided with an annular step for the narrow section to abut against the end of the narrow section when it is inserted into the inner core 3. On the one hand, the abutment between the narrow section and the annular step completes the positioning of the feed shaft 2 in the inner core 3. On the other hand, it completes the limiting function of the feed shaft 2, so that it can maintain its position and will not move down relative to the inner core 3 as drilling work progresses, thus affecting the positioning of the downhole drilling tools.

[0038] The inner core 3 extends out of the top of the locking sleeve 1, and the shear pin 4 is installed at the position where the inner core 3 extends out of the locking sleeve 1. This facilitates the operation of those skilled in the art at the position where the inner core 3 extends out of the locking sleeve 1 after the inner core 3 and the locking sleeve 1 are engaged, thereby improving the connection efficiency and convenience between the inner core 3 and the feed shaft 2.

[0039] In a preferred embodiment of the present invention, the outer peripheral wall of the inner core 3 is further provided with a plurality of lower limit blocks 8 located below the locking block 6. Each lower limit block 8 is equally spaced along the circumference of the inner core 3. The top of the lower limit block 8 is rotatably connected to the inner core 3. A second reset spring is provided between the bottom of the lower limit block 8 and the inner core 3 to push the lower limit block 8 toward the locking sleeve 1. The locking sleeve 1 is provided with an annular groove at the position corresponding to the lower limit block 8. The top of the annular groove has a chamfer to facilitate the upper sliding of the lower limit block 8. The bottom of the annular groove has a limiting step for engaging the bottom of the lower limit block 8. The lower limit block 8 sits on the limiting step of the annular groove on the locking sleeve 1 to achieve lower limiting. More importantly, if the downhole drilling tool cannot continue drilling, the entire drilling tool needs to be lifted with the feed shaft 2. At this time, the feed shaft 2 no longer limits the locking block 6, so the locking block 6 no longer acts as an upper and lower limit between the inner core 3 and the locking device outer sleeve 1. Then, once the downhole drilling tool moves down, it can continue to form a locking action with the casing through the lower limit block 8, avoiding the downhole drilling tool from detaching and causing an accident. On the other hand, when the downhole drilling tool is working, the lower limit block 8 and the locking block 6 work together to form a lower limit action on the downhole drilling tool. If the inner drilling tool moves down, it will cause the inner drilling tool to fall to the bottom of the well, causing a downhole accident.

[0040] Furthermore, a lower limit block mounting groove 16 is formed on the outer peripheral wall of the inner core 3 to fit into the lower limit block 8. A first retaining ring 7 is provided between the top of the lower limit block mounting groove 16 and the locking sleeve 1 to prevent the top of the lower limit block 8 from dislodging from the lower limit block mounting groove 16. A second retaining ring 9 is provided between the bottom of the lower limit block mounting groove 16 and the locking sleeve 1 to prevent the bottom of the lower limit block 8 from moving downward. In the specific installation process, the second return spring is fixed in the hole of the lower limit block 8 with a highly viscous grease and placed into the corresponding lower limit block mounting groove 16 of the inner core 3. After fixing the first retaining ring 7 and the second retaining ring 9 on the inner core 3, the lower limit block 8 can be blocked in the lower limit block mounting groove 16, thereby fixing the lower limit block 8. Moreover, a notch is formed at the position of the lower limit block 8 corresponding to the second retaining ring 9, so that the lower limit block 8 is extended outward by the action of the second return spring, and the notch abuts against the second retaining ring 9, thus preventing it from dislodging from the lower limit block mounting groove 16.

[0041] In a preferred embodiment of the present invention, the outer peripheral wall of the inner core 3 is further provided with a plurality of torque transmission block mounting grooves 17 located below the lower limit block 8. Each torque transmission block mounting groove 17 is equally spaced along the axial direction of the inner core 3. Each torque transmission block mounting groove 17 is provided with a torque transmission block 10 and a third return spring for pushing the torque transmission block 10 toward the locking sleeve 1 as a whole. The locking sleeve 1 is provided with a plurality of torque transmission grooves corresponding one-to-one with each torque transmission block 10. After the inner core 3 moves into place, each torque transmission block 10 is tightly engaged in each torque transmission groove. The torque transmission block 10 and the torque transmission groove of the locking sleeve 1 realize torque transmission. During the drilling process, the downhole drilling tool transmits torque to the locking sleeve 1, the casing string and the drilling rig through the torque transmission block 10. If the top drive of the drilling rig does not rotate, the downhole drilling tool can rotate while the locking sleeve 1 and the casing string do not rotate. If the top drive rotates, composite drilling can be achieved by rotating the downhole drilling tool and the locking sleeve 1 and the casing string at the same time. Both of these drilling methods can be used. Regardless of whether the top drive rotates, i.e., whether the locking outer sleeve 1 and the casing string rotate, the inner core 3 must not rotate relative to the locking outer sleeve 1 and the casing string; otherwise, it indicates that the torque transmission block 10 has failed, and the locking outer sleeve 1 and the casing string cannot transmit torque to the downhole drill bit, resulting in low drilling efficiency or even drill bit loss accidents. The preferred torque transmission groove is a spline groove structure to achieve meshing between the torque transmission groove and the torque transmission block 10, ensuring a locking effect between the torque transmission block 10 and the torque transmission groove. Furthermore, both ends of the preferred torque transmission block 10 and both ends of the preferred torque transmission groove are fitted chamfered structures to ensure rapid axial installation and disengagement of the torque transmission block 10 and the torque transmission groove. During the specific installation process, the third return spring is fixed in the hole of the torque transmission block 10 using highly viscous grease, and the torque transmission block 10 is placed into the corresponding torque transmission block mounting groove 17 on the inner core 3.

[0042] Furthermore, the bottom of the torque block mounting groove 17 is provided with a third retaining ring 11 for limiting the bottom of the torque block 10 from disengaging from the torque block mounting groove 17. The second retaining ring 9 is located at the top of the torque block mounting groove 17 and abuts against the top of the torque block 10. When installing the torque block 10, the torque block 10 is first inserted into the torque block mounting groove 17 corresponding to the second retaining ring 9, so that the second retaining ring 9 limits the torque block 10. Then, the third retaining ring 11 is fixed on the inner core 3, which can keep the torque block 10 in the torque block mounting groove 17, thereby fixing the torque block 10.

[0043] Among them, the first retaining ring 7, the second retaining ring 9, and the third retaining ring 11 are all connected to the inner core 3 by bolts. The first retaining ring 7, the second retaining ring 9, and the third retaining ring 11 are all formed by connecting pairs of semi-circular rings, which facilitates the installation of each retaining ring to the inner core 3.

[0044] Furthermore, both ends of the locking device outer sleeve 1 are equipped with connecting buckles for connecting the sleeve string. The connecting buckle at the top is detachably connected to an installation fixture 13, which is coaxially arranged with the locking device outer sleeve 1 and has a cylindrical structure. The inner circumferential wall of the installation fixture 13 is smoothly connected to the inner circumferential wall of the locking device outer sleeve 1. During the specific installation process, the installation fixture 13 is placed into the connecting buckle at the upper end of the locking device outer sleeve 1 and sits on the buckle root step. Since the installation fixture 13 is a section of cylindrical tube, its inner diameter is consistent with the minimum inner diameter of the locking device outer sleeve 1. Before lowering the inner core 3 into the locking device outer sleeve 1, the torque transmission block 10 is aligned with the torque transmission groove at the lower part of the locking device outer sleeve 1. During the lowering process, the torque transmission block 10 can be smoothly lowered into the installation fixture 13 under the action of the chamfer, and then smoothly enters the locking device outer sleeve 1. The lower limit block 8 can be pushed by hand to compress the spring and then smoothly enter the installation fixture 13, and then smoothly enters the locking device outer sleeve 1. When the lower limit block 8 sits on the step of the annular groove of the locking sleeve 1, and at the same time the torque transmission block 10 enters the torque transmission groove at the bottom of the locking sleeve 1, it indicates that it has been lowered into place. Press down the feed shaft 2, align the shearing hole 14 on the upper part of the feed shaft 2 with the shearing hole 14 on the upper part of the inner core 3, and install the shearing pin 4 to fix the feed shaft 2 and the inner core 3.

[0045] Any adaptive changes made according to actual needs are within the scope of protection of this invention.

[0046] It should be noted that, for those skilled in the art, it is obvious that the present invention is not limited to the details of the exemplary embodiments described above, and that the invention can be implemented in other specific forms without departing from the spirit or essential characteristics of the invention. Therefore, the embodiments should be considered illustrative and non-limiting in all respects, and the scope of the invention is defined by the appended claims rather than the foregoing description. Thus, all variations falling within the meaning and scope of equivalents of the claims are intended to be included within the present invention. No reference numerals in the claims should be construed as limiting the scope of the claims.

[0047] 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. A locking device suitable for use in cased hole drilling, characterized in that, The locking sleeve and the inner core are both straight cylindrical structures, the bottom of the locking sleeve is connected with the casing string, the inner wall of the locking sleeve is provided with a limiting ring groove coaxial with the locking sleeve, a plurality of limiting pins above the limiting ring groove, the inner core is provided with a plurality of guide through holes coaxial with the limiting ring groove and equidistantly arranged along the circumference of the inner core, the guide through holes are movably provided with clamping blocks capable of self-resetting and separating from the limiting ring groove; The top end of the inner core is inserted with a hollow six-square structure sending shaft for pushing the clamping blocks into the limiting ring groove, the sending shaft is provided with a limiting sliding groove extending along the axial direction of the sending shaft at the position corresponding to the limiting pins, the limiting pins are respectively abutted on the upper and lower end walls of the limiting sliding groove when the sending shaft is pressed down or moved up, the inner core is provided with a shear pin for fixing the sending shaft after the sending shaft is inserted in place, and the shear pin is inserted at the six-square structure; The bottom end of the inner core is inserted with a hollow connecting shaft, the connecting shaft is connected with the inner core and the sending shaft, the bottom of the connecting shaft is connected with the downhole drilling tool, and the downhole drilling tool is located in the casing string; The side of the clamping block away from the sending shaft is provided with a reset slot penetrating the outer circumferential surface of the clamping block, the reset slot is provided with a blocking strip extending out of the two sides of the clamping block, the two ends of the blocking strip are fixed on the inner core, and the blocking strip and the bottom of the reset slot are provided with a first reset spring for driving the clamping block to reset; The sending shaft includes a wide section for pushing the clamping block to move and a narrow section connected to the bottom end of the wide section, the wide section and the narrow section are located below the six-square structure, the outer circumferential wall of the wide section is abutted on the inner end of the guide through hole, and the narrow section has a space for the clamping block to separate from the limiting ring groove at the inner end of the guide through hole.

2. A locker device suitable for use in cased drilling according to claim 1, characterized in that, An annular step is arranged on the inner circumferential wall of the inner core for abutting with the end of the narrow section when the narrow section is inserted into the inner core.

3. A locker device suitable for use in cased drilling according to claim 2, characterized in that, The top end of the inner core extends out of the locking sleeve, and the shear pin is installed at the position of the inner core extending out of the locking sleeve.

4. A locker device suitable for use in cased drilling according to claim 3, characterized in that, The outer circumferential wall of the inner core is further provided with a plurality of lower limiting blocks below the clamping block, the lower limiting blocks are equidistantly arranged along the circumference of the inner core, the top of the lower limiting block is rotatably connected to the inner core, the bottom of the lower limiting block and the inner core are provided with a second reset spring for pushing the lower limiting block to move towards the locking sleeve, the locking sleeve is provided with an annular groove at the position corresponding to the lower limiting block, the top of the annular groove has a chamfer facilitating the upward sliding of the lower limiting block, and the bottom of the annular groove has a limiting step for clamping the bottom of the lower limiting block.

5. A locker device suitable for use in cased drilling according to claim 4, characterized in that, An lower limiting block mounting groove is arranged on the outer circumferential wall of the inner core for embedding the lower limiting block, a first blocking ring is arranged between the top of the lower limiting block mounting groove and the locking sleeve for limiting the top of the lower limiting block from coming out of the lower limiting block mounting groove, and a second blocking ring is arranged between the bottom of the lower limiting block mounting groove and the locking sleeve for limiting the bottom of the lower limiting block from moving downward.

6. A locker device suitable for use in cased drilling according to claim 5, characterized in that, The outer peripheral wall of the inner core is further provided with a plurality of torque block mounting grooves below the lower limit block, the torque block mounting grooves are equidistantly arranged along the axial direction of the inner core, the torque block mounting grooves are provided with torque blocks and third return springs for pushing the torque blocks towards the lock outer sleeve as a whole, the lock outer sleeve is provided with a plurality of torque grooves corresponding to the torque blocks, and the torque blocks are tightly clamped in the torque grooves after the inner core is moved into position.

7. A locker device suitable for use in cased drilling according to claim 6, characterized in that, The bottom of the torque block mounting groove is provided with a third stop ring for limiting the bottom of the torque block from being separated from the torque block mounting groove, and the second stop ring is located at the top of the torque block mounting groove and abuts against the top of the torque block.

8. A locker device suitable for use in cased drilling according to claim 7, characterized in that, Both ends of the lock outer sleeve are provided with connecting buckles for connecting the sleeve string, the connecting buckle at the top is detachably connected with a mounting tool which is coaxially arranged with the lock outer sleeve and has a cylindrical structure, and the inner peripheral wall of the mounting tool is smoothly connected with the inner peripheral wall of the lock outer sleeve.

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