Drill bit and drilling method based on adaptive regulation of number of blades according to formation characteristics

Abstract

The application discloses a drill bit and a drilling method based on formation characteristics change adaptive regulation and control of the number of blades, and belongs to the technical field of drilling engineering, comprising an upper drilling tool connecting joint and a drill bit crown; a plurality of blades are arranged on the drill bit crown, and cutting teeth are arranged on the blades; at least one blade is an axial telescopic blade, and the rest of the blades are fixed blades; the axial telescopic blade comprises a body and a telescopic part; the cutting teeth on the axial telescopic blade are located outside a track circle; the cutting teeth outside the track circle on the fixed blade are outer ring cutting teeth, and the cutting teeth inside the track circle are inner ring cutting teeth; when the telescopic part is retracted upwards to a position, the telescopic part and the corresponding body form a complete blade, and the drill bit is in a conventional form; when the telescopic part is extended downwards, the fixed blade is in a concave structure relative to the axial telescopic blade, and the drill bit is in a concave form. When the drill bit is used in a soft formation, the drill bit is drilled in the concave form, and when the drill bit is used in a hard formation, the drill bit is drilled in the conventional form.

Description

Technical Field

[0001] This invention belongs to the field of drilling engineering technology, specifically relating to a drill bit and drilling method that adaptively adjusts the number of cutter wings based on changes in formation characteristics. Background Technology

[0002] Improving rock-breaking efficiency is a hot research topic in the field of drilling engineering. Methods to improve drilling rock-breaking efficiency mainly include: enhancing drilling mechanical parameters (such as increasing drill pressure and rotational speed); enhancing drilling hydraulic parameters (such as increasing pump pressure and displacement); enhancing the performance of the rock-breaking tool itself (such as PDC axe-shaped teeth); and enhancing the stability of the rock-breaking tool (such as using vibration-damping tools). However, all four methods have reached their respective bottlenecks, resulting in various problems such as drill string vibration, well leakage, and limited vibration suppression capabilities. Meanwhile, as the drilled formations become deeper and more complex, there are alternating soft and hard formations, and the frequency of these alternations increases significantly. This phenomenon leads to PDC drill bit tooth breakage. Roller cone bits, on the other hand, have a limited lifespan and cannot effectively adapt to such deep and complex formations. Therefore, there is an urgent need for a drill bit that can adapt to deep and complex formations while also offering high drilling speed and long lifespan.

[0003] Based on this, the present invention provides a drill bit and drilling method that adaptively adjust the number of cutting blades based on changes in formation characteristics. The drilling mode of this drill bit depends on the hardness of the formation rock. In deep, complex, and difficult-to-drill formations, whether from soft to hard or from hard to soft formations, this drill bit can change its drilling mode according to the rock hardness. In soft formations, the drill bit drills in a concave shape, which can automatically release bottom hole stress and exert the effect of bottom hole stress-induced unloading to improve drilling speed. In hard formations, it drills in a conventional shape. Compared with the concave shape, the conventional shape of this drill bit increases the number of cutting blades, which can increase the speed and extend the service life of the rock breaking tool. Summary of the Invention

[0004] The purpose of this invention is to overcome the shortcomings of the prior art and provide a drill bit that adaptively adjusts the number of cutter wings based on changes in formation characteristics.

[0005] To achieve the above objectives, the present invention adopts the following technical solution: A drill bit that adaptively adjusts the number of cutter wings based on changes in formation characteristics, including a fixedly connected upper drill string connector and a drill bit crown. The crown of the drill bit body is provided with several blades evenly arranged along the circumferential direction, and the blades are provided with several cutting teeth distributed along the generatrix direction; At least one blade is an axially retractable blade, and the rest are fixed blades. The crown of the drill bit rotates around its own central axis. The rotational envelope of the axially retractable blade extending to the head side of the crown of the drill bit is a trajectory circle, and the end of the fixed blade extending to the head side of the crown of the drill bit is located inside the trajectory circle. The axially retractable cutter blade includes a body disposed on the crown of the drill bit body and a telescopic part that can extend and retract along the axial direction, and the cutting teeth on the axially retractable cutter blade are disposed on the telescopic part; The cutting teeth on the axially retractable blade are located outside the trajectory circle, forming outer ring cutting teeth; The cutting teeth on the fixed blade that are located outside the trajectory circle are called outer ring cutting teeth, and the cutting teeth that are located inside the trajectory circle are called inner ring cutting teeth. The drill bit body crown is provided with a drive unit for driving the telescopic part to extend downward. When all telescopic parts retract upwards to their positions, they form a complete blade with the corresponding body, and the drill bit is in its conventional form. When all telescopic parts extend downwards, the fixed blade wings are concave relative to the axially telescopic blade wings, and the drill bit is in a concave shape. The upper drill string connection joint has a through drilling fluid channel in the middle along the axial direction. The drill bit crown has a drill bit cavity that communicates with the drilling fluid channel. A nozzle is provided on the drill bit crown and the nozzle is connected to the drill bit cavity through a channel.

[0006] Preferably, the drive unit includes a force transmission plate that slides axially within the drill bit cavity, and a spring is provided between the top of the force transmission plate and the annular step of the drill bit cavity; The telescopic part is connected to the force transmission plate through a connecting plate, and the crown of the drill bit body is provided with a movable groove for the connecting plate to pass through and to provide space for the connecting plate to move up and down.

[0007] Preferably, an axial limiting mechanism is provided between the telescopic part and the drill bit crown to enable the telescopic part to move axially.

[0008] Preferably, the axial limiting mechanism includes a guide post disposed on the radially inner side of the telescopic part, and the drill bit body crown is provided with a guide hole disposed axially inward from the drilling end and slidingly engaging with the corresponding guide post.

[0009] Preferably, the guide hole extends into the inner cavity of the drill bit, and the bottom end of the force transmission plate is provided with a pressure post that can cooperate with the guide hole, and the bottom end of the pressure post abuts against the top end of the corresponding guide post.

[0010] The present invention also provides a drilling method for adaptively adjusting the number of cutter wings based on changes in formation characteristics.

[0011] The drilling method based on adaptive adjustment of the number of cutting blades according to changes in formation characteristics is implemented using a drill bit that adaptively adjusts the number of cutting blades according to changes in formation characteristics. The drilling method includes a method in which the drill bit is in a conventional shape, a method in which the drill bit is in a concave shape, a method in which the drill bit changes from a conventional shape to a concave shape, and a method in which the drill bit changes from a concave shape to a conventional shape.

[0012] Preferably, the method for placing the drill bit in a conventional configuration includes the following steps: Step 11: The spring causes the telescopic part on the axially telescopic cutter wing to extend downwards, and the drill bit is in a concave shape. The cutting teeth on the telescopic part first contact the bottom of the well. Step 12: Apply drilling torque, and the axially retractable blade breaks the rock. The rock's resistance to the drill bit causes the telescopic part to move upward and compress the spring until all telescopic parts retract upward and form a complete blade with the corresponding body. The drill bit then returns to its normal shape, and the spring accumulates elastic potential energy. Step 13: Continuously apply drilling torque. Under the combined action of drilling torque and spring elastic potential energy, all cutting teeth on the cutter blades rotate to break the rock. During the rock breaking process, the nozzle sprays drilling fluid to clean the cutting teeth and carry the rock cuttings to the surface.

[0013] Preferably, the method for the drill bit to be in a concave shape includes the following steps: Step 21: The spring causes the telescopic part on the axially telescopic cutter wing to extend downwards, and the drill bit is in a concave shape. The cutting teeth on the telescopic part first contact the bottom of the well. Step 22: Apply drilling torque, and the axially retractable blade breaks the rock. The rock's resistance to the drill bit causes the telescopic part to move upward and compress the spring, but it is not enough to make the telescopic part fully retract into place. The drill bit remains in a concave shape, and the spring accumulates elastic potential energy. Step 23: Continuously apply drilling torque. Under the combined action of drilling torque and spring elastic potential energy, the cutting teeth on the axially retractable cutter blade break the rock at the outer ring of the drill bit. As the cutting teeth on the axially retractable cutter blade break the rock, a rock column is formed in the concave area inside the axially retractable cutter blade, effectively releasing the bottom hole pressure. As rock breaking progresses, the inner ring cutting teeth on the fixed cutter blades contact the rock column, and under the action of drilling torque, they break the rock column in the inner ring of the drill bit. The entire rock breaking drilling process is achieved under the premise of balancing the rock breaking capacity of the drill bit center and the drill bit outer ring. During the rock-breaking process, drilling fluid is sprayed from the nozzle to clean the cutting teeth and carry the rock cuttings to the surface.

[0014] Preferably, the method for changing a drill bit from a conventional shape to a concave shape includes the following steps: Step 31: The drill bit is in its normal configuration, and all the cutting teeth on the blades rotate to break the rock. Step 32: As the rock's resistance to the drill bit decreases, the spring causes the telescopic part to extend outward, putting the drill bit in a concave state. Step 33: The cutting teeth on the axially retractable cutter blade break the rock at the outer ring of the drill bit; As the cutting teeth on the axially retractable cutter blade break the rock, a rock column is formed in the concave area inside the axially retractable cutter blade, effectively releasing the bottom hole pressure. As rock breaking progresses, the inner ring cutting teeth on the fixed cutter blades contact the rock column, and under the action of drilling torque, they break the rock column in the inner ring of the drill bit. The entire rock breaking drilling process is achieved under the premise of balancing the rock breaking capacity of the drill bit center and the drill bit outer ring. During the rock-breaking process, drilling fluid is sprayed from the nozzle to clean the cutting teeth and carry the rock cuttings to the surface.

[0015] Preferably, the method for changing the drill bit from a concave shape to a conventional shape includes the following steps: Step 41: The drill bit is in a concave shape. The cutting teeth on the axially retractable blade break the rock in the outer ring of the drill bit, forming a rock column in the concave area inside the axially retractable blade. The inner ring cutting teeth on the fixed blade break the rock column in the inner ring of the drill bit. Step 42: As the rock's resistance to the drill bit increases, the cutting teeth on the axially retractable blades slow down the rock breaking speed at the outer ring, and the length of the rock column gradually decreases until it disappears completely. At this point, the rock's resistance causes the telescopic part to retract completely into place, and the drill bit returns to its normal shape. Step 43: Continuously apply drilling torque. Under the combined action of drilling torque and spring elastic potential energy, all cutting teeth on the cutter blades rotate to break the rock. During the rock breaking process, the nozzle sprays drilling fluid to clean the cutting teeth and carry the rock cuttings to the surface.

[0016] The beneficial effects of this invention are: The drilling mode of the drill bit of this invention depends on the hardness of the formation rock. In deep, complex, and difficult-to-drill formations, whether from soft to hard or from hard to soft formations, the drill bit can change its drilling mode according to the rock hardness. In soft formations, the drill bit drills in a concave shape, which can automatically release the bottom hole stress and exert the effect of bottom hole stress-induced unloading to improve drilling speed. In hard formations, it drills in a conventional shape. Compared with the concave shape, the conventional shape of the drill bit increases the number of blades, which can increase the speed and extend the service life of the rock breaking tool. Attached Figure Description

[0017] The accompanying drawings, which form part of this application, are used to provide a further understanding of this application. The illustrative embodiments of this application and their descriptions are used to explain this application and do not constitute an undue limitation of this application.

[0018] Figure 1 This is a schematic three-dimensional view of the drill bit structure of the present invention, which adaptively adjusts the number of cutter wings based on changes in formation characteristics; Figure 2 This is a schematic front view of the drill bit structure of the present invention, which adaptively adjusts the number of cutter wings based on changes in formation characteristics; Figure 3 This is a schematic bottom view of the drill bit structure of the present invention, which adaptively adjusts the number of cutter wings based on changes in formation characteristics; Figure 4 yes Figure 3 Sectional view along axis AA; Figure 5 This is a three-dimensional schematic diagram of the structure of the drill bit body crown after removing the telescopic part in this invention. Figure 1 ; Figure 6 This is a three-dimensional schematic diagram of the structure of the drill bit body crown after removing the telescopic part in this invention. Figure 2 ; Figure 7 This is a schematic front view of the structure of the drill bit body crown after the telescopic part is removed in this invention; Figure 8 yes Figure 7 BB-direction sectional view; Figure 9 This is a schematic bottom view of the structure of the drill bit body crown after the telescopic part is removed in this invention; Figure 10 yes Figure 9 CC-direction sectional view; Figure 11 This is a schematic diagram of the telescopic part in this invention; Figure 12 This is a schematic diagram of the force transmission plate in this invention; in: 1. Upper drill string connection joint; 11. Drill fluid flow channel; 12. Drill string connection buckle; 13. Cylindrical surface; 14. Joint welding bevel; 2. Drill bit body crown; 21. Drill bit inner cavity; 22. Nozzle; 23. Channel; 24. Movable groove; 25. Guide hole; 26. Drill bit body welding bevel; 3. Cutting blade; 31. Body; 32. Telescopic part; 321. Connecting plate; 322. Guide post; 4. Cutting teeth; 5. Force transmission plate; 51. Pressure post; 6. Spring; 7. Track circle. Detailed Implementation

[0019] It should be noted that the following detailed descriptions are illustrative and intended to provide further explanation of this application. Unless otherwise specified, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application pertains.

[0020] It should be noted that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the exemplary embodiments according to this application. As used herein, the singular form is intended to include the plural form as well, unless the context clearly indicates otherwise. Furthermore, it should be understood that when the terms "comprising" and / or "including" are used in this specification, they indicate the presence of features, steps, operations, devices, components, and / or combinations thereof.

[0021] In this invention, terms such as "upper," "lower," "bottom," and "top" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are merely relational terms determined for the convenience of describing the structural relationship of the various components or elements of this invention, and do not specifically refer to any component or element in this invention, and should not be construed as limiting this invention.

[0022] In this invention, terms such as "connected" and "linked" should be interpreted broadly, indicating a fixed connection, an integral connection, or a detachable connection; a direct connection or an indirect connection through an intermediate medium. Those skilled in the art can determine the specific meaning of these terms in this invention based on the specific circumstances, and they should not be construed as limitations on the invention.

[0023] The present invention will be further described below with reference to the accompanying drawings and embodiments.

[0024] Example 1: like Figures 1-12 As shown, a drill bit that adaptively adjusts the number of cutter wings based on changes in formation characteristics includes a fixedly connected upper drill string connector 1 and a drill bit crown 2. The upper drill string connector 1 and the drill bit crown 2 are welded together. The upper outer part of the upper drill string connector 1 has a drill string connector buckle 12, the middle outer part has a cylindrical surface 13, and the bottom outer part has a connector welding bevel 14. The middle part of the cylindrical surface 13 has an upper buckle jaw. The top of the drill bit crown 2 has a drill bit body welding bevel 26, which matches the connector welding bevel 14. The crown portion 2 of the drill bit body is provided with a plurality of blades 3 evenly arranged along the circumferential direction, and the blades 3 are provided with a plurality of cutting teeth 4 distributed along the generatrix direction; At least one blade 3 is an axially retractable blade, and the remaining blades are fixed blades; the drill body crown 2 rotates around its own central axis, and the rotational envelope of the axially retractable blade extending to the head side end of the drill body crown 2 is a trajectory circle 7, and the end of the fixed blade extending to the head side of the drill body crown 2 is located inside the trajectory circle 7. The axially retractable cutter blade includes a body 31 disposed on the crown portion 2 of the drill bit body and a telescopic portion 32 that can extend and retract along the axial direction. The cutting teeth 4 on the axially retractable cutter blade are disposed on the telescopic portion 32. The cutting tooth 4 on the axially retractable blade is located outside the trajectory circle 7 and is an outer ring cutting tooth; The cutting teeth 4 located outside the trajectory circle 7 on the fixed blade are outer ring cutting teeth, and the cutting teeth 4 located inside the trajectory circle 7 are inner ring cutting teeth. The drill bit body crown 2 is provided with a drive unit for driving the telescopic part 32 to extend downward; When all telescopic parts 32 retract upwards to their positions, they form a complete blade 3 with the corresponding body 31, and the drill bit is in its conventional form. When all telescopic parts 32 extend downwards, the fixed blade 3 has an inward concave structure relative to the axially telescopic blade, and the drill bit is in an inward concave shape. The upper drill string connection joint 1 has a through drilling fluid channel 11 in the middle along the axial direction. The drill bit crown 2 has a drill bit inner cavity 21 that communicates with the drilling fluid channel 11. The drill bit crown 2 is provided with a nozzle 22, which is connected to the drill bit inner cavity 21 through a channel 23.

[0025] Preferably, the drive unit includes a force transmission plate 5 that slides axially within the drill bit cavity 21, and a spring 6 is provided between the top of the force transmission plate 5 and the annular step of the drill bit cavity 21; in the natural state, the extension part 32 of the spring 6 is in a downward extension state, that is, in the natural state, the drill bit is in a concave shape. The telescopic part 32 is connected to the force transmission plate 5 through the connecting plate 321, and the drill bit crown 2 is provided with a movable groove 24 for the connecting plate 321 to pass through and for providing space for the connecting plate 321 to move up and down.

[0026] Preferably, an axial limiting mechanism is provided between the telescopic part 32 and the drill bit crown 2 to enable the telescopic part 32 to move axially.

[0027] Preferably, the axial limiting mechanism includes a guide post 322 disposed radially inside the telescopic part 32, and the drill bit crown 2 is provided with a guide hole 25 disposed axially inward from the drilling end and slidingly engaging with the corresponding guide post 322.

[0028] Preferably, the guide hole 25 extends into the drill bit cavity 21, and the bottom end of the force transmission plate 5 is provided with a pressure post 51 that can cooperate with the guide hole 25, and the bottom end of the pressure post 51 abuts against the top end of the corresponding guide post 322.

[0029] Example 2: The drilling method based on adaptive adjustment of the number of cutting blades based on changes in formation characteristics is implemented using the drill bit based on adaptive adjustment of the number of cutting blades based on changes in formation characteristics in Example 1. The drilling method includes a method in the conventional form of the drill bit, a method in the concave form of the drill bit, a method from the conventional form to the concave form of the drill bit, and a method from the concave form to the conventional form of the drill bit.

[0030] Preferably, the method for placing the drill bit in a conventional configuration includes the following steps: Step 11: Spring 6 causes the telescopic part 32 on the axially telescopic cutter wing to extend downward, the drill bit is in a concave shape, and the cutting teeth 4 on the telescopic part 32 first contact the bottom of the well. Step 12: Apply drilling torque, and the axially retractable blade breaks the rock. The rock's resistance to the drill bit causes the telescopic part 32 to move upward and compress the spring 6 until all telescopic parts 32 retract upward and return to their original positions to form a complete blade 3 with the corresponding body 31. The drill bit then returns to its normal shape, and the spring 6 accumulates elastic potential energy. Step 13: Continuously apply drilling torque. Under the combined action of drilling torque and the elastic potential energy of spring 6, all the cutting teeth 4 on the blades 3 rotate to break the rock. During the rock breaking process of the cutting teeth 4, the nozzle 22 sprays drilling fluid to clean the cutting teeth 4 and carry the rock cuttings to the surface.

[0031] The drilling method with the drill bit in its conventional form is applied to hard formations. The high strength and abrasiveness of hard formations result in high rock-breaking resistance, which causes the telescopic part 32 to move upward to compress the spring 6, and the drill bit takes on a conventional form. On the one hand, the number of cutting blades participating in rock breaking increases, thereby increasing the rock-breaking speed; on the other hand, the elastic potential energy accumulated by the spring 6 also provides a certain rock-breaking pressure, further enhancing the rock-breaking ability.

[0032] Preferably, the method for the drill bit to be in a concave shape includes the following steps: Step 21: Spring 6 causes the telescopic part 32 on the axially telescopic cutter wing to extend downward, the drill bit is in a concave shape, and the cutting teeth 4 on the telescopic part 32 first contact the bottom of the well. Step 22: Apply drilling torque, and the axially retractable blade breaks the rock. The rock's resistance to the drill bit causes the telescopic part 32 to move upward and compress the spring 6, but it is not enough to cause the telescopic part 32 to fully retract into place. The drill bit remains in a concave shape, and the spring 6 accumulates elastic potential energy. Step 23: Continuously apply drilling torque. Under the combined action of drilling torque and the elastic potential energy of spring 6, the cutting teeth 4 on the axially retractable blade break the rock in the outer ring of the drill bit. The outer ring of the drill bit refers to the outer area of ​​the trajectory circle 7. As the cutting teeth 4 on the axially retractable cutter blade break the rock, a rock column is formed in the concave area inside the axially retractable cutter blade, which effectively releases the bottom hole pressure. The concave area refers to the inner area of ​​the trajectory circle 7. As rock breaking progresses, the inner ring cutting teeth on the fixed cutter blades contact the rock column, and under the action of drilling torque, they break the rock column in the inner ring of the drill bit. The entire rock breaking drilling process is achieved under the premise of balancing the rock breaking capacity of the drill bit center and the drill bit outer ring. The inner ring of the drill bit refers to the internal area of ​​the trajectory circle 7. During the rock-breaking process of cutting tooth 4, nozzle 22 sprays drilling fluid to clean cutting tooth 4 and carry rock cuttings to the surface.

[0033] The drilling method with the drill bit in a concave shape is applied to soft formations. In soft formations, the rock breaking resistance is small and insufficient to cause the extension section 32 to fully retract into place, thus making the drill bit in a concave shape. During drilling, the interior of the trajectory circle 7 forms a concave area of ​​the drill bit, and the concave area forms a rock column that effectively releases the bottom hole pressure.

[0034] Preferably, the method for changing a drill bit from a conventional shape to a concave shape includes the following steps: Step 31: The drill bit is in its normal configuration, and all the cutting teeth 4 on the blades 3 rotate to break the rock. Step 32: As the rock's resistance to the drill bit decreases, the spring 6 causes the telescopic part 32 to extend outward, putting the drill bit in a concave state. Step 33: The cutting teeth 4 on the axially retractable blade break the rock at the outer ring of the drill bit; As the cutting teeth 4 on the axially retractable cutter blade break the rock, a rock column is formed in the concave area inside the axially retractable cutter blade, effectively releasing the bottom hole pressure. As rock breaking progresses, the inner ring cutting teeth on the fixed cutter blades contact the rock column, and under the action of drilling torque, they break the rock column in the inner ring of the drill bit. The entire rock breaking drilling process is achieved under the premise of balancing the rock breaking capacity of the drill bit center and the drill bit outer ring. During the rock-breaking process of cutting tooth 4, nozzle 22 sprays drilling fluid to clean cutting tooth 4 and carry rock cuttings to the surface.

[0035] The method of changing the drill bit from a conventional shape to a concave shape is applied to drilling from hard formations to soft subsurfaces.

[0036] Preferably, the method for changing the drill bit from a concave shape to a conventional shape includes the following steps: Step 41: The drill bit is in a concave shape. The cutting teeth 4 on the axially retractable blade break the rock in the outer ring of the drill bit and form a rock column in the concave area inside the axially retractable blade. The inner ring cutting teeth on the fixed blade break the rock column in the inner ring of the drill bit. Step 42: The rock's resistance to the drill bit increases, the cutting teeth 4 on the axially retractable blade slow down the rock breaking speed of the outer ring, and the length of the rock column gradually decreases until it disappears completely. At this time, the rock's resistance causes the telescopic part 32 to retract completely into place, and the drill bit is in its normal state. Step 43: Continuously apply drilling torque. Under the combined action of drilling torque and the elastic potential energy of spring 6, all the cutting teeth 4 on the blades 3 rotate to break the rock. During the rock breaking process of the cutting teeth 4, the nozzle 22 sprays drilling fluid to clean the cutting teeth 4 and carry the rock cuttings to the surface.

[0037] The method of changing the drill bit from a concave shape to a conventional shape is applied to drilling from soft formations to hard subsurfaces.

[0038] The drilling mode of the drill bit of this invention depends on the hardness of the formation rock. In deep, complex, and difficult-to-drill formations, whether from soft to hard or from hard to soft formations, the drill bit can change its drilling mode according to the rock hardness. In soft formations, the drill bit drills in a concave shape, which can automatically release the bottom hole stress and exert the effect of bottom hole stress-induced unloading to improve drilling speed. In hard formations, it drills in a conventional shape. Compared with the concave shape, the conventional shape of the drill bit increases the number of blades, which can increase the speed and extend the service life of the rock breaking tool.

[0039] While the specific embodiments of the present invention have been described above in conjunction with the accompanying drawings, they are not intended to limit the present invention. Those skilled in the art should understand that various modifications or variations that can be made by those skilled in the art without creative effort based on the technical solutions of the present invention are still within the protection scope of the present invention.

Claims

1. A drill bit that adaptively adjusts the number of cutter wings based on changes in formation characteristics, characterized in that, This includes the fixedly connected upper drill string connector and the drill bit body crown; The crown of the drill bit body is provided with several blades evenly arranged along the circumferential direction, and the blades are provided with several cutting teeth distributed along the generatrix direction; At least one blade is an axially retractable blade, and the rest are fixed blades. The crown of the drill bit rotates around its own central axis. The rotational envelope of the axially retractable blade extending to the head side of the crown of the drill bit is a trajectory circle, and the end of the fixed blade extending to the head side of the crown of the drill bit is located inside the trajectory circle. The axially retractable cutter blade includes a body disposed on the crown of the drill bit body and a telescopic part that can extend and retract along the axial direction, and the cutting teeth on the axially retractable cutter blade are disposed on the telescopic part; The cutting teeth on the axially retractable blade are located outside the trajectory circle, forming outer ring cutting teeth; The cutting teeth on the fixed blade that are located outside the trajectory circle are called outer ring cutting teeth, and the cutting teeth that are located inside the trajectory circle are called inner ring cutting teeth. The drill bit body crown is provided with a drive unit for driving the telescopic part to extend downward. When all telescopic parts retract upwards to their positions, they form a complete blade with the corresponding body, and the drill bit is in its conventional form. When all telescopic parts extend downwards, the fixed blade wings are concave relative to the axially telescopic blade wings, and the drill bit is in a concave shape. The upper drill string connection joint has a through drilling fluid channel in the middle along the axial direction. The drill bit crown has a drill bit cavity that communicates with the drilling fluid channel. A nozzle is provided on the drill bit crown and the nozzle is connected to the drill bit cavity through a channel.

2. The drill bit with adaptive control of the number of cutter wings based on changes in formation characteristics as described in claim 1, characterized in that, The drive unit includes a force transmission plate that slides axially within the drill bit cavity, and a spring is provided between the top of the force transmission plate and the annular step of the drill bit cavity. The telescopic part is connected to the force transmission plate through a connecting plate, and the crown of the drill bit body is provided with a movable groove for the connecting plate to pass through and to provide space for the connecting plate to move up and down.

3. The drill bit with adaptive control of the number of cutter wings based on changes in formation characteristics as described in claim 2, characterized in that, An axial limiting mechanism is provided between the telescopic part and the crown of the drill bit body to enable the telescopic part to move axially.

4. The drill bit with adaptive control of the number of cutter wings based on changes in formation characteristics as described in claim 3, characterized in that, The axial limiting mechanism includes a guide post disposed on the radial inner side of the telescopic part, and the crown of the drill bit body is provided with a guide hole disposed axially inward from the drilling end and slidingly engaging with the corresponding guide post.

5. The drill bit with adaptive control of the number of cutter wings based on changes in formation characteristics as described in claim 4, characterized in that, The guide hole extends into the inner cavity of the drill bit, and the bottom end of the force transmission plate is provided with a pressure column that can cooperate with the guide hole. The bottom end of the pressure column abuts against the top end of the corresponding guide column.

6. A drilling method for adaptively adjusting the number of cutting blades based on changes in formation characteristics, implemented using a drill bit as described in any one of claims 2 to 5, characterized in that... The drilling methods include methods with the drill bit in a conventional shape, methods with the drill bit in a concave shape, methods with the drill bit changing from a conventional shape to a concave shape, and methods with the drill bit changing from a concave shape to a conventional shape.

7. The drilling method for adaptively adjusting the number of cutting blades based on changes in formation characteristics as described in claim 6, characterized in that, The method for placing the drill bit in its normal configuration includes the following steps: Step 11: The spring causes the telescopic part on the axially telescopic cutter wing to extend downwards, and the drill bit is in a concave shape. The cutting teeth on the telescopic part first contact the bottom of the well. Step 12: Apply drilling torque, and the axially retractable blade breaks the rock. The rock's resistance to the drill bit causes the telescopic part to move upward and compress the spring until all telescopic parts retract upward and form a complete blade with the corresponding body. The drill bit then returns to its normal shape, and the spring accumulates elastic potential energy. Step 13: Continuously apply drilling torque. Under the combined action of drilling torque and spring elastic potential energy, all cutting teeth on the cutter blades rotate to break the rock. During the rock breaking process, the nozzle sprays drilling fluid to clean the cutting teeth and carry the rock cuttings to the surface.

8. The drilling method for adaptively adjusting the number of cutter wings based on changes in formation characteristics as described in claim 6, characterized in that, The method for positioning the drill bit in a concave configuration includes the following steps: Step 21: The spring causes the telescopic part on the axially telescopic cutter wing to extend downwards, and the drill bit is in a concave shape. The cutting teeth on the telescopic part first contact the bottom of the well. Step 22: Apply drilling torque, and the axially retractable blade breaks the rock. The rock's resistance to the drill bit causes the telescopic part to move upward and compress the spring, but it is not enough to make the telescopic part fully retract into place. The drill bit remains in a concave shape, and the spring accumulates elastic potential energy. Step 23: Continuously apply drilling torque. Under the combined action of drilling torque and spring elastic potential energy, the cutting teeth on the axially retractable cutter blade break the rock at the outer ring of the drill bit. As the cutting teeth on the axially retractable cutter blade break the rock, a rock column is formed in the concave area inside the axially retractable cutter blade, effectively releasing the bottom hole pressure. As rock breaking progresses, the inner ring cutting teeth on the fixed cutter blades contact the rock column, and under the action of drilling torque, they break the rock column in the inner ring of the drill bit. The entire rock breaking drilling process is achieved under the premise of balancing the rock breaking capacity of the drill bit center and the drill bit outer ring. During the rock-breaking process, drilling fluid is sprayed from the nozzle to clean the cutting teeth and carry the rock cuttings to the surface.

9. The drilling method for adaptively adjusting the number of cutter wings based on changes in formation characteristics as described in claim 6, characterized in that, The method for changing a drill bit from a conventional shape to a concave shape includes the following steps: Step 31: The drill bit is in its normal configuration, and all the cutting teeth on the blades rotate to break the rock. Step 32: As the rock's resistance to the drill bit decreases, the spring causes the telescopic part to extend outward, putting the drill bit in a concave state. Step 33: The cutting teeth on the axially retractable cutter blade break the rock at the outer ring of the drill bit; As the cutting teeth on the axially retractable cutter blade break the rock, a rock column is formed in the concave area inside the axially retractable cutter blade, effectively releasing the bottom hole pressure. As rock breaking progresses, the inner ring cutting teeth on the fixed cutter blades contact the rock column, and under the action of drilling torque, they break the rock column in the inner ring of the drill bit. The entire rock breaking drilling process is achieved under the premise of balancing the rock breaking capacity of the drill bit center and the drill bit outer ring. During the rock-breaking process, drilling fluid is sprayed from the nozzle to clean the cutting teeth and carry the rock cuttings to the surface.

10. The drilling method for adaptively adjusting the number of cutting blades based on changes in formation characteristics as described in claim 6, characterized in that, The method for changing a drill bit from a concave shape to a conventional shape includes the following steps: Step 41: The drill bit is in a concave shape. The cutting teeth on the axially retractable blade break the rock in the outer ring of the drill bit, forming a rock column in the concave area inside the axially retractable blade. The inner ring cutting teeth on the fixed blade break the rock column in the inner ring of the drill bit. Step 42: As the rock's resistance to the drill bit increases, the cutting teeth on the axially retractable blades slow down the rock breaking speed at the outer ring, and the length of the rock column gradually decreases until it disappears completely. At this point, the rock's resistance causes the telescopic part to retract completely into place, and the drill bit returns to its normal shape. Step 43: Continuously apply drilling torque. Under the combined action of drilling torque and spring elastic potential energy, all cutting teeth on the cutter blades rotate to break the rock. During the rock breaking process, the nozzle sprays drilling fluid to clean the cutting teeth and carry the rock cuttings to the surface.

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