Pdc bits and drilling methods for highly abrasive formations

Abstract

The application discloses a PDC drill bit and drilling method for high-abrasive strata, and belongs to the technical field of oil production engineering, which comprises a drill bit body, a polishing piece, polishing balls and an adjusting assembly, and the adjusting assembly is connected with an intelligent control system; a plurality of polishing balls are rotatably installed on the drill bit body, and the polishing piece is installed on the drill bit body and located between two adjacent polishing balls; the adjusting assembly is arranged in the interior of the drill bit body, and the adjusting assembly comprises a rotating piece and an extending piece; the output end of the rotating piece is connected with the polishing ball; and the output end of the extending piece is connected with the polishing piece.

Description

Technical Field

[0001] This application belongs to the field of oil production engineering technology, and specifically relates to PDC drill bits and drilling methods for highly abrasive formations. Background Technology

[0002] Ultra-deep formations are generally characterized by high compressive strength (>200 MPa), high quartz content (>40%), and strong heterogeneity. Common lithologies include dense sandstone, chert layers, volcanic rock interlayers, and granite intrusions, representing typical highly abrasive formations. In these formations, traditional PDC drill bits face multiple failure modes, including severe wear, thermal fracturing, tooth breakage, and vortex instability. This results in short drilling footage per trip, low rate of penetration (ROP), and frequent tripping, severely limiting drilling efficiency and economic benefits.

[0003] Currently, high-performance PDC drill bits or PDC-roller cone composite drill bits are mainly used for drilling in the field. Among them, PDC drill bits remain the main choice due to their high aggression and continuous cutting advantages; while PDC-roller cone composite drill bits (such as NOV's Kymera™) are used for extremely hard or highly abrasive interlayers, compensating for the insufficient cutting ability of PDC through roller cone impact crushing. In terms of construction technology, a combination of high drill pressure, low rotation speed, and strong hydraulic cuttings carrying parameters is generally adopted, along with an efficient drilling fluid system to enhance cuttings carrying capacity. However, even so, the field application results are still not ideal: the average life of a single PDC drill bit is less than 15 hours, the ROP is generally below 2m / h, and the proportion of drill bit failures during non-productive time (NPT) exceeds 20%.

[0004] Existing technologies primarily improve PDC drill bit performance by optimizing tooth layout, enhancing material properties, and improving hydraulic structure: While the aforementioned improvements have delayed drill bit failure to some extent, their core remains based on the static cutting concept and cannot solve a fundamental problem: high-hardness rock cuttings (especially micron-sized quartz particles) generated during drilling become trapped between the cutting teeth and the wellbore / bottom, repeatedly crushed by the continuous rotation of the drill bit, resulting in a severe secondary grinding effect. This effect not only accelerates the lateral wear of the shoulder teeth and gauge-maintaining teeth but also exacerbates heat accumulation and microcrack propagation, making it a key contributing factor to early drill bit failure. Currently, no systematic solution to avoid secondary wear through a dynamic avoidance-active chip removal-automatic reset mechanism has been found in existing patents and technical solutions. Summary of the Invention

[0005] To address the aforementioned issues, this application provides a PDC drill bit for highly abrasive formations, comprising a drill bit body, a grinding element, a grinding ball, and an adjustment assembly, wherein the adjustment assembly is connected to an intelligent control system; the intelligent control system controls the operation of the adjustment assembly as needed. Multiple grinding balls are rotatably mounted on the drill bit body, and grinding elements are mounted on the drill bit body between two adjacent grinding balls; the grinding elements and grinding balls are alternately spaced to cooperate in drilling operations; The adjustment component is located inside the drill bit body and includes a rotating component and an extension component. The output end of the rotating component is connected to the grinding ball, and the output end of the extension component is connected to the grinding component. The rotating component is controlled by an intelligent control system to control the operation of the grinding ball, thereby ensuring the stability of the grinding effect.

[0006] Furthermore, the rotating component includes a rotating motor and a mounting shaft; a transmission assembly is installed at the output end of the rotating motor, the transmission assembly is connected to the mounting shaft, and the mounting shaft passes through the drill bit body and is fixedly connected to the grinding ball.

[0007] Furthermore, the transmission assembly includes a first bevel gear and a second bevel gear that mesh with each other; the output end of the rotary motor is connected to the first bevel gear; and the second bevel gear is fixedly mounted on the mounting shaft. The first and second bevel gears have strong load-bearing capacity and can transmit power more smoothly.

[0008] Furthermore, the polishing ball is provided with a smooth surface and a toothed surface; polishing teeth are installed on the toothed surface; The drill bit body has an internal installation chamber, and a locking component is installed inside the installation chamber; the locking component fixes or unlocks the position of the grinding ball, and the locking component improves the stability of the grinding ball in different states.

[0009] Furthermore, the locking assembly includes a positioning seat and a limiting plate; the positioning seat is fixedly installed inside the installation chamber, the limiting plate is installed on the positioning seat, and a movable part is slidably installed between the limiting plate and the positioning seat; an electric telescopic cylinder is fixedly installed on the outer peripheral surface of the limiting plate, the fixed end of the movable part is connected to the output end of the electric telescopic cylinder, and a snap-fit ​​plate is installed on the output end of the movable part, which snaps into the surface of the grinding ball.

[0010] Furthermore, the extension includes multiple sets of extension units; each extension unit includes a telescopic rod, one end of which is installed inside the drill bit body, and the other end of which is fixedly connected to the grinding component.

[0011] Furthermore, the telescopic rod includes a threaded rod and a threaded sleeve connected by threads; the threaded sleeve is rotatably installed in the drill bit body, the threaded rod is slidably connected to the drill bit body, and the end of the threaded rod away from the threaded sleeve is fixedly connected to the grinding part; a limit hole is provided on the threaded rod; an electric telescopic cylinder two and a locking rod are provided in the drill bit body, the fixed end of the electric telescopic cylinder two is fixedly connected to the inner wall of the drill bit body, the fixed end of the locking rod is connected to the electric telescopic cylinder two, and the output end of the locking rod cooperates with the limit hole to lock the threaded rod. The stability of the grinding part is improved by the cooperation of the locking rod and the limit hole. The drill bit body is equipped with a drive assembly, and the output end of the drive assembly is connected to the threaded sleeve.

[0012] Furthermore, the drive assembly includes a servo motor, which is fixedly installed inside the drill bit body, and a positioning gear one is fixedly installed at the output end of the servo motor; a positioning gear two is fixedly installed on the outer surface of the threaded sleeve, and the positioning gear two meshes with the positioning gear one.

[0013] Furthermore, a threaded connecting post is fixedly installed on the drill bit body; The grinding component is provided with shoulder teeth; a distance sensor is installed on the grinding component and the grinding ball.

[0014] This application provides a drilling method for a PDC drill bit used in highly abrasive formations, based on the aforementioned PDC drill bit for highly abrasive formations, comprising: The grinding ball and grinding tool are adjusted to contact the rock wall and apply a predetermined pressure by adjusting the components; Controlling the rotation of the drill bit body to perform intermittent operations on the rock formation; During non-operational periods, the rotating component drives the grinding ball to a position where it does not contact the rock face, and the extending component drives the grinding component to a position where it does not contact the rock face.

[0015] Furthermore, during non-operational periods, the rotating component drives the grinding ball to a position where it does not contact the rock face, and the extending component drives the grinding element to a position where it does not contact the rock face, including: The rotating motor drives the transmission assembly to rotate the mounting shaft, which in turn adjusts the grinding ball from facing the rock wall with the toothed surface to facing the rock wall with the smooth surface. The drive assembly drives the threaded sleeve to rotate, and the threaded sleeve drives the threaded rod to move away from the rock wall, thus moving the grinding part away from the rock wall.

[0016] Compared with the prior art, this application has the following advantages: 1. This application uses the extension to retract, causing the grinding part to move away from the rock formation, while the rotating part drives the grinding ball to rotate away from the rock formation. This causes the generated rock cuttings to fall automatically under the action of gravity and drilling fluid. Then, the extension and grinding ball are reset to grind the rock formation again. This avoids secondary grinding between the teeth of the grinding part and grinding ball and the rock cuttings when crushing the rock formation, reduces the wear on the teeth during drilling, and increases the service life of the drill bit.

[0017] 2. This application achieves precise extension and rotation of the grinding parts and grinding balls by setting distance sensors on the grinding parts and grinding balls and monitoring the wear status and position of the cutting teeth in real time, thereby optimizing drilling parameters and improving drilling efficiency and safety.

[0018] 3. This application uses a locking assembly to reliably fix the position of the grinding ball and the grinding part, effectively preventing the displacement of the parts due to vibration or impact during drilling, ensuring that the drill bit works stably in highly abrasive formations, and quickly switching to chip removal mode during non-operational time, significantly improving the adaptability and reliability of the drill bit.

[0019] Other features and advantages of this application will be set forth in the description which follows, and will be apparent in part from the description, or may be learned by practicing the application. The objectives and other advantages of this application may be realized and obtained by means of the structures pointed out in the description, claims and drawings. Attached Figure Description

[0020] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0021] Figure 1 A schematic diagram of the overall structure in an embodiment of the present invention is shown.

[0022] Figure 2 A vertical internal sectional view is shown in an embodiment of the present invention.

[0023] Figure 3 It shows Figure 2 A magnified view of a portion of point A in the middle.

[0024] Figure 4 A cross-sectional view of the interior in a transverse direction is shown in an embodiment of the present invention.

[0025] Figure 5 A schematic diagram of the installation of the drive component in an embodiment of the present invention is shown.

[0026] In the diagram, 1. Drill bit body; 2. Threaded connecting post; 3. Grinding part; 4. Grinding ball; 5. Grinding tooth; 6. Shoulder tooth; 7. Smooth surface; 8. Rotating motor; 9. Bevel gear one; 10. Mounting shaft; 11. Telescopic rod; 12. Mounting chamber; 13. Bevel gear two; 14. Moving part; 15. Limiting plate; 16. Positioning seat; 17. Snap-fit ​​plate; 18. Locking rod; 19. Limiting hole; 20. Servo motor; 21. Positioning gear one; 22. Positioning gear two; 23. Threaded sleeve; 24. Threaded rod. Detailed Implementation

[0027] To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, the technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0028] This application provides a PDC drill bit for highly abrasive formations, referenced. Figure 1 It includes a drill bit body 1, a grinding component 3, a grinding ball 4, and an adjustment component. The adjustment component is connected to an intelligent control system. The intelligent control system monitors whether the grinding component 3 and the grinding ball 4 are in contact with the rock wall and apply a predetermined pressure, and makes adjustments based on the status. Multiple grinding balls 4 are rotatably mounted on the drill bit body 1, and the grinding element 3 is mounted on the drill bit body 1 between two adjacent grinding balls 4; The adjustment component is located inside the drill bit body 1. The adjustment component includes a rotating part and an extension part. The output end of the rotating part is connected to the grinding ball 4. The output end of the extension part is connected to the grinding part 3.

[0029] The drill bit body 1 uses the teeth on the grinding parts 3 and grinding balls 4 located on the lower side to drill deeper. As the drill bit body 1 rotates, the teeth crush the rock formation, forming rock cuttings. During drilling, the drill bit body 1 intermittently drives the grinding balls 4 and grinding parts 3 to rotate and grind the rock wall. The interval between each rotation reduces the amount of rock cuttings in the gap between the drill bit body 1 and the rock wall. After the rock cuttings are generated, the extension retracts to move the grinding parts 3 away from the rock formation, while the rotating part drives the teeth on the grinding balls 4 to rotate away from the rock formation. This causes the rock cuttings to fall automatically under the action of gravity and drilling fluid. Then, the extension and grinding balls 4 reset to grind the rock formation again. This avoids secondary grinding between the teeth on the grinding parts 3 and grinding balls 4 and the rock cuttings when crushing the rock formation, reducing wear on the teeth during drilling and increasing the service life of the drill bit.

[0030] In one embodiment of the present invention, reference is made to Figure 2 The rotating component includes a rotating motor 8 and a mounting shaft 10; a transmission assembly is installed at the output end of the rotating motor 8, the transmission assembly is connected to the mounting shaft 10, and the mounting shaft 10 passes through the drill bit body 1 and is fixedly connected to the grinding ball 4.

[0031] The transmission assembly includes a first bevel gear 9 and a second bevel gear 13 that mesh with each other; the output end of the rotary motor 8 is connected to the first bevel gear 9; and the second bevel gear 13 is fixedly mounted on the mounting shaft 10.

[0032] The rotating motor 8 drives the bevel gear 9 to rotate, which in turn drives the bevel gear 13 that meshes with it to rotate. The rotation of the bevel gear 13 drives the mounting shaft 10 to rotate, which in turn drives the grinding ball 4 to rotate, thereby changing the contact surface between the grinding ball 4 and the sidewall of the rock stratum.

[0033] This application uses the extension to retract, causing the grinding part 3 to move away from the rock layer, while the rotating part drives the grinding ball 4 to rotate away from the rock layer. This causes the generated rock cuttings to fall automatically under the action of gravity and drilling fluid. Then, the extension and grinding ball 4 are reset to grind the rock layer again, avoiding secondary grinding between the teeth of the grinding part 3 and the grinding ball 4 and the rock cuttings when crushing the rock layer. This reduces the wear on the teeth during drilling and increases the service life of the drill bit.

[0034] The polishing ball 4 is provided with a smooth surface 7 and a toothed surface; polishing teeth 5 are installed on the toothed surface. The drill bit body 1 has an installation chamber 12 inside, and a locking component is provided inside the installation chamber 12; the locking component fixes or unlocks the position of the grinding ball 4.

[0035] When the grinding teeth 5 of the grinding ball 4 are on the outer side, the grinding teeth 5 grind and crush the rock layer as the drill bit body 1 rotates. The crushed rock layer produces rock chips. If the grinding continues, the rock chips will remain in the grinding gap between the rock layer and the lower grinding teeth 5, causing damage to the grinding teeth 5. By rotating the mounting shaft 10, the grinding ball 4 is driven to rotate, so that the grinding teeth 5 of the grinding ball 4 rotate to the inner side, and the smooth surface 7 rotates to the side closer to the side wall of the drilled rock layer. In this way, the generated rock chips can fall and will not remain in the gap between the drill bit and the rock wall.

[0036] In one embodiment of the present invention, reference is made to Figure 3 and Figure 4 The locking assembly includes a positioning seat 16 and a limiting plate 15. The positioning seat 16 is fixedly installed in the installation chamber 12, and the limiting plate 15 is installed on the positioning seat 16. A movable part 14 is slidably installed between the limiting plate 15 and the positioning seat 16. An electric telescopic cylinder is fixedly installed on the outer peripheral surface of the limiting plate 15. The fixed end of the movable part 14 is connected to the output end of the electric telescopic cylinder. A snap-fit ​​plate 17 is installed on the output end of the movable part 14, and the snap-fit ​​plate 17 snaps into the surface of the grinding ball 4.

[0037] The electric telescopic cylinder drives the movable part 14 to move towards the rock wall, causing the locking plate 17 to engage with the grinding ball 4, thus fixing the position of the grinding ball 4. When it is necessary to rotate the grinding ball 4, the electric telescopic cylinder drives the movable part 14 to move away from the rock wall, causing the locking plate 17 to disengage from the grinding ball 4. After the grinding ball 4 has finished rotating, the locking plate 17 fixes the position of the grinding ball 4 again.

[0038] In one embodiment of the present invention, an elastic rod is provided at the end of the movable member 14 away from the snap-fit ​​plate 17.

[0039] When the elastic rod is extended, the locking plate 17 can be embedded into the grinding ball 4; when the elastic rod is retracted, the locking plate 17 disengages from the grinding ball 4; after the grinding ball 4 rotates, the locking plate 17 at one end of the movable part 14 is embedded into the surface of the grinding ball 4, locking the position of the grinding ball 4 and preventing the grinding ball 4 from being misaligned when crushing the rock wall.

[0040] The extension and retraction of the elastic rod are achieved by the movement of the moving part 14 driven by the electric telescopic cylinder. Its function is to ensure that the locking plate 17 can reliably engage or disengage from the grinding ball 4 to complete the locking and unlocking action.

[0041] In one embodiment of the present invention, the extension member includes multiple sets of extension units; the extension unit includes a telescopic rod 11, one end of the telescopic rod 11 is installed inside the drill bit body 1, and the other end of the telescopic rod 11 is fixedly connected to the grinding member 3.

[0042] refer to Figure 5 The telescopic rod 11 includes a threaded rod 24 and a threaded sleeve 23 connected by threads; the threaded sleeve 23 is rotatably installed inside the drill bit body 1, the threaded rod 24 is slidably connected to the drill bit body 1, and the end of the threaded rod 24 away from the threaded sleeve 23 is fixedly connected to the grinding part 3; a limit hole 19 is provided on the threaded rod 24; an electric telescopic cylinder 2 and a locking rod 18 are provided inside the drill bit body 1, the fixed end of the electric telescopic cylinder 2 is fixedly connected to the inner wall of the drill bit body 1, the fixed end of the locking rod 18 is connected to the electric telescopic cylinder 2, and the output end of the locking rod 18 cooperates with the limit hole 19 to lock the threaded rod 24; The drill bit body 1 is equipped with a drive assembly, and the output end of the drive assembly is connected to the threaded sleeve 23.

[0043] As the drill bit body 1 rotates, the grinding component 3 crushes the rock wall. During crushing, the grinding component 3 moves away from the side wall of the drill bit body 1 under the action of the telescopic rod 11. Multiple sets of grinding components 3 are unfolded and surround the drill bit body 1. After crushing the rock wall, the telescopic rod 11 shortens, causing the grinding component 3 to adhere to the side wall surface of the drill bit body 1, thereby increasing the gap between the drill bit edge and the rock wall, allowing the generated rock chips to fall and reducing the possibility of rock chips remaining in the gap between the drill bit and the rock wall. The threaded sleeve 23 rotates in the forward direction, causing the threaded rod 24 to drive the grinding component 3 away from the drill bit body 1. The threaded sleeve 23 rotates in the reverse direction, causing the threaded rod 24 to drive the grinding component 3 closer to the drill bit body 1. When the threaded rod 24 moves, the locking rod 18 is pulled out from the limiting hole 19. When the threaded rod 24 stops moving, the electric telescopic cylinder 2 drives the locking rod 18 to embed into the limiting hole 19, thereby locking the position of the threaded rod 24 and thus locking the position of the grinding component 3.

[0044] The drive assembly includes a servo motor 20, which is fixedly installed inside the drill bit body 1. A positioning gear 21 is fixedly installed at the output end of the servo motor 20. A positioning gear 22 is fixedly installed on the outer surface of the threaded sleeve 23, and the positioning gear 22 meshes with the positioning gear 21.

[0045] The servo motor 20 drives the threaded sleeve 23 to rotate through the meshing positioning gear 1 21 and positioning gear 22. The rotation of the threaded sleeve 23 interacts with the threaded rod 24, thereby driving the threaded rod 24 to move.

[0046] A threaded connecting post 2 is fixedly installed on the drill bit body 1; The grinding component 3 is provided with shoulder teeth 6; a distance sensor is installed on the grinding component 3 and the grinding ball 4.

[0047] The drill bit body 1 is equipped with a controller, which can control the operation of the electric telescopic cylinder, servo motor 20 and rotary motor 8; the positions of the grinding ball 4 and the grinding part 3 are locked by the moving part 14 and the locking part; the grinding part 3 is densely equipped with shoulder teeth 6, and distance sensors are provided on the side of the grinding part 3 and the grinding ball 4 near the grinding teeth 5. The distance sensors can detect the vertical distance between them and the central axis of the drill bit body 1; the position of the shoulder teeth 6 on the grinding part 3 and the grinding teeth 5 on the grinding ball 4 is determined by the distance sensors.

[0048] This application, by setting distance sensors on the grinding parts and grinding balls and combining them with a controller for intelligent adjustment components, can monitor the wear status and position of the cutting teeth in real time, and achieve precise extension, retraction and rotation of the grinding parts and grinding balls, thereby optimizing drilling parameters and improving drilling efficiency and safety.

[0049] This application proposes a drilling method for a PDC drill bit used in highly abrasive formations, based on the aforementioned PDC drill bit for highly abrasive formations, comprising: The grinding ball 4 and grinding piece 3 are adjusted to contact the rock wall and apply a predetermined pressure by adjusting the components; Control the rotation of the drill bit body 1 to perform intermittent operations on the rock formation; During non-operational periods, the rotating component drives the grinding ball 4 to a position where it does not contact the rock wall, and the extending component drives the grinding component 3 to a position where it does not not contact the rock wall.

[0050] During non-operating hours, the rotating component drives the grinding ball 4 to a position where it does not contact the rock wall, and the extending component drives the grinding component 3 to a position where it does not contact the rock wall, including: The rotating motor 8 drives the transmission assembly to rotate the mounting shaft 10, and the mounting shaft 10 drives the grinding ball 4 to adjust from the toothed surface facing the rock wall to the smooth surface 7 facing the rock wall. The drive assembly drives the threaded sleeve 23 to rotate, and the threaded sleeve 23 drives the threaded rod 24 to move away from the rock wall, so that the grinding part 3 is away from the rock wall.

[0051] Although this application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of this application.

Claims

1. A PDC drill bit for highly abrasive formations, characterized in that, It includes a drill bit body (1), a grinding component (3), a grinding ball (4), and an adjustment assembly, the adjustment assembly being connected to an intelligent control system; The drill bit body (1) is provided with an installation groove, and multiple grinding balls (4) are rotatably installed in the installation groove. The grinding part (3) is installed on the drill bit body (1) and is located between two adjacent grinding balls (4). The adjustment component is located inside the drill bit body (1). The adjustment component includes a rotating part and an extension part. The output end of the rotating part is connected to the grinding ball (4). The output end of the extension part is connected to the grinding part (3).

2. The PDC drill bit for highly abrasive formations according to claim 1, characterized in that, The rotating component includes a rotating motor (8) and a mounting shaft (10); the output end of the rotating motor (8) is equipped with a transmission assembly, which is connected to the mounting shaft (10). The mounting shaft (10) passes through the drill bit body (1) and is fixedly connected to the grinding ball (4).

3. The PDC drill bit for highly abrasive formations according to claim 2, characterized in that, The transmission assembly includes a bevel gear one (9) and a bevel gear two (13) that mesh with each other; the output end of the rotating motor (8) is connected to bevel gear one (9); and bevel gear two (13) is fixedly mounted on the mounting shaft (10).

4. The PDC drill bit for highly abrasive formations according to claim 3, characterized in that, The polishing ball (4) is provided with a smooth surface (7) and a toothed surface; polishing teeth (5) are installed on the toothed surface. The drill bit body (1) has an installation chamber (12) inside, and a locking component is provided inside the installation chamber (12); the locking component fixes or unlocks the position of the grinding ball (4).

5. The PDC drill bit for highly abrasive formations according to claim 4, characterized in that, The locking assembly includes a positioning seat (16) and a limiting plate (15); the positioning seat (16) is fixedly installed in the installation chamber (12), the limiting plate (15) is installed on the positioning seat (16), and a movable part (14) is slidably installed between the limiting plate (15) and the positioning seat (16); an electric telescopic cylinder is fixedly installed on the outer peripheral surface of the limiting plate (15), the fixed end of the movable part (14) is connected to the output end of the electric telescopic cylinder, and a snap-fit ​​plate (17) is installed on the output end of the movable part (14), and the snap-fit ​​plate (17) snaps against the surface of the grinding ball (4).

6. The PDC drill bit for highly abrasive formations according to claim 4, characterized in that, The extension includes multiple sets of extension units; the extension unit includes a telescopic rod (11), one end of which is installed inside the drill bit body (1), and the other end of which is fixedly connected to the grinding part (3).

7. The PDC drill bit for highly abrasive formations according to claim 6, characterized in that, The telescopic rod (11) includes a threaded rod (24) and a threaded sleeve (23) with threaded connection; the threaded sleeve (23) is rotatably installed inside the drill bit body (1), the threaded rod (24) is slidably connected to the drill bit body (1), and the end of the threaded rod (24) away from the threaded sleeve (23) is fixedly connected to the grinding part (3); a limit hole (19) is opened on the threaded rod (24); an electric telescopic cylinder II and a locking rod (18) are provided inside the drill bit body (1), the fixed end of the electric telescopic cylinder II is fixedly connected to the inner wall of the drill bit body (1), the fixed end of the locking rod (18) is connected to the output end of the electric telescopic cylinder II, and the output end of the locking rod (18) cooperates with the limit hole (19) to lock the threaded rod (24); The drill bit body (1) is provided with a drive assembly, and the output end of the drive assembly is connected to the threaded sleeve (23).

8. The PDC drill bit for highly abrasive formations according to claim 7, characterized in that, The drive assembly includes a servo motor (20), which is fixedly installed inside the drill bit body (1). A positioning gear one (21) is fixedly installed at the output end of the servo motor (20). A positioning gear two (22) is fixedly installed on the outer surface of the threaded sleeve (23), and the positioning gear two (22) meshes with the positioning gear one (21).

9. The PDC drill bit for highly abrasive formations according to claim 8, characterized in that, A threaded connecting post (2) is fixedly installed on the drill bit body (1); The grinding part (3) is provided with shoulder teeth (6); a distance sensor is installed on the grinding part (3) and the grinding ball (4).

10. A drilling method for a PDC drill bit used in highly abrasive formations, based on the PDC drill bit for highly abrasive formations according to any one of claims 1-9, characterized in that, include: The grinding ball (4) and grinding piece (3) are adjusted to contact the rock wall and apply a predetermined pressure by adjusting the components; Control the rotation of the drill bit body (1) to perform intermittent operations on the rock strata; During non-operational periods, the rotating component drives the grinding ball (4) to not contact the rock wall, and the extending component drives the grinding component (3) to not contact the rock wall.

11. The drilling method for a PDC drill bit in highly abrasive formations according to claim 10, characterized in that, During non-operational periods, the rotating component drives the grinding ball (4) to a position where it does not contact the rock wall, and the extending component drives the grinding component (3) to a position where it does not contact the rock wall, including: The rotating motor (8) drives the transmission assembly to rotate the mounting shaft (10), and the mounting shaft (10) drives the grinding ball (4) to adjust from the toothed surface facing the rock wall to the smooth surface (7) facing the rock wall; The drive assembly drives the threaded sleeve (23) to rotate, and the threaded sleeve (23) drives the threaded rod (24) to move away from the rock wall, so that the grinding part (3) moves away from the rock wall.

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