Multi-bladed adaptive PDC bit

Abstract

The application provides a multi-blade adaptive PDC drill bit, belonging to the technical field of PDC drill bits, and comprising a drill bit body, a blade wing part and an adjusting nozzle. One end of the drill bit body is a threaded end for connecting a drill rod, and the other end is a rock breaking end. A plurality of blade wing parts are arranged at intervals along the circumferential direction of the rock breaking end. At least one adjusting nozzle is embedded in a branch flow channel. The adjusting nozzle comprises a valve assembly, a sliding block and an elastic member. The valve assembly is arranged at one end of the branch flow channel close to the drill bit body, and is used for controlling the on-off and opening degree of the drilling fluid flow. The sliding block is slidingly arranged in the branch flow channel. An acceleration flow channel is further arranged in the sliding block and is in communication with the branch flow channel. One end of the elastic member is connected with the sliding block, and the other end is connected with the valve assembly. The elastic member is used for providing elastic force to drive the valve assembly to slidingly extend and retract, so as to adaptively adjust the drilling fluid flow. The pressure required for the sliding of the sliding block is greater than the pressure required for the sliding of the valve assembly. The application can effectively solve the problem of unstable rock cleaning and cooling effect of the PDC drill bit in the prior art.

Description

Technical Field

[0001] This invention belongs to the field of PDC drill bit technology, and more specifically, relates to a multi-blade adaptive PDC drill bit. Background Technology

[0002] PDC drill bits are short for polycrystalline diamond composite drill bits, also known as polycrystalline diamond cutting block drill bits or composite tooth drill bits. PDC drill bits consist of a drill body, PDC cutting teeth, and a nozzle. PDC drill bits break rocks through cutting; their cutting teeth easily penetrate the formation under drilling pressure and move forward to shear the rock under torque. Multiple PDC cutting teeth work simultaneously, resulting in more free surfaces in the rock at the bottom of the well, and the rock is easily broken under shearing action, thus achieving high rock-breaking efficiency and fast drilling speed.

[0003] However, in actual drilling processes, traditional PDC drill bits still face some technical bottlenecks. Chinese patent (application number 202411858202.X) discloses a PDC drill bit with extended nozzles, including a connecting main rod, a cutting head on the upper part of the connecting rod, an installation assembly on the cutting head, a working assembly on the installation assembly, an auxiliary assembly on the outer wall of the cutting head, and a cleaning assembly on the top of the cutting head. The cleaning assembly contains multiple extended cleaning nozzles for cleaning the original PDC drill bit. This invention adds extended cleaning nozzles to the PDC drill bit to clean it, preventing soil adhesion and improving its working efficiency, achieving high-efficiency drilling, reducing tripping and tripping times due to poor rock-clearing performance, extending the single-trip drilling footage, reducing drilling costs, increasing the shear force on the PDC drill bit's tooth surface, increasing the flow velocity near the teeth, shortening the distance between the nozzle outlet and the bottom of the well, reducing jet diffusion, reducing hydraulic energy loss, enhancing the rock-clearing and cooling effect of the drill bit teeth in specific areas, and extending the service life of the PDC drill bit. However, simply shortening the distance to the bottom of the well by increasing the nozzle length limits the coverage of rock removal. Furthermore, the extended nozzle cannot dynamically adjust the flow rate and injection pressure according to the bottom-of-well conditions (such as rock cuttings concentration and pressure changes), resulting in unstable rock removal and cooling effects. Summary of the Invention

[0004] The purpose of this invention is to provide a multi-blade adaptive PDC drill bit to solve the problem of unstable rock clearing and cooling effects in existing PDC drill bits.

[0005] To achieve the above objectives, the technical solution adopted by this invention is as follows: A multi-blade adaptive PDC drill bit is provided, comprising a drill body, cutter wings, and an adjusting nozzle. The drill body has a main flow channel along the axial direction and branch flow channels. The branch flow channels extend obliquely to the surface of the drill body and communicate with the main flow channel. One end of the drill body is a threaded end for connecting the drill rod, and the other end is a rock-breaking end. Multiple fluid outlet holes are distributed circumferentially on the rock-breaking end, and these holes communicate with the main flow channel. Each fluid outlet hole is equipped with a conventional nozzle. Multiple cutter wings are spaced apart along the circumferential direction of the rock-breaking end. The cutter wings are connected to the rock-breaking end of the drill body and are equipped with a cutting structure. Any two adjacent cutter wings... A water groove is formed between the blade wings; at least one regulating nozzle is embedded in the branch flow channel, and the regulating nozzle includes a valve assembly, a slider, and an elastic member; the valve assembly is located at one end of the branch flow channel near the drill bit body and is used to control the flow rate and opening degree of the drilling fluid; the slider is slidably disposed in the branch flow channel and has sliding damping between it and the branch flow channel, and the slider also has an acceleration flow channel connected to the branch flow channel; one end of the elastic member is connected to the slider and the other end is connected to the valve assembly, and the elastic member is used to provide elastic force to drive the valve assembly to extend and slide, so as to adaptively adjust the drilling fluid flow rate; the pressure required for the slider to slide is greater than the pressure required for the valve assembly to slide.

[0006] The beneficial effects of the multi-blade adaptive PDC drill bit provided by this invention are as follows: Compared with the prior art, the adjusting nozzle is in a locked state during normal drilling, with only the ordinary nozzle working to ensure cooling of the cutting teeth and cuttings carrying at the bottom of the well; when mud packing occurs, the adjusting nozzle can also achieve a graded response function of "valve assembly opening first (rapid pressure relief and cuttings removal) → slider moving later (full flow flushing)". For example, when the cuttings concentration at the bottom of the well exceeds 5%, the valve assembly opens first under low pressure, increasing the local cuttings removal flow rate; if the pressure continues to rise (such as severe mud packing), the slider slides to trigger full-channel injection, forming a rotating jet, improving the cuttings removal efficiency by more than 30%; after the mud pack is removed, the discharge rate and pump pressure are reduced, the pressure difference is lower than the threshold, and the nozzle returns to a locked state to protect the drill bit cutting teeth and extend its service life. Attached Figure Description

[0007] To more clearly illustrate the technical solutions in the embodiments of the present invention, the drawings used in the description of the embodiments or the prior art 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.

[0008] Figure 1 This is a schematic diagram of the structure of the multi-blade adaptive PDC drill bit provided in one embodiment of the present invention;

[0009] Figure 2 This is a schematic diagram of the structure of the adjusting nozzle provided in one embodiment of the present invention;

[0010] Figure 3 This is a schematic diagram of the structure of the acceleration channel provided in one embodiment of the present invention;

[0011] Figure 4 This is a schematic diagram of the anti-collision limiting structure provided in one embodiment of the present invention;

[0012] Figure 5 This is a schematic diagram showing the positional structure of the valve assembly and the elastic member according to one embodiment of the present invention;

[0013] Figure 6 This is a schematic diagram of the structure of the drill bit body provided in one embodiment of the present invention;

[0014] The labels for the attached figures are as follows:

[0015] 10. Drill body; 101. Main flow channel; 102. Branch flow channel; 103. Threaded end; 104. Rock-breaking end; 105. Fluid outlet; 106. Ordinary nozzle; 11. Water tank;

[0016] 20. Blade section; 201. Blade diameter protection section; 202. Blade crown section; 21. Cutting structure; 211. Main cutting tooth; 212. Secondary cutting tooth;

[0017] 30. Adjusting nozzle; 31. Valve assembly; 311. Valve seat; 312. Valve stem; 313. Valve head; 32. Slider; 321. Acceleration channel; 3221. Inlet section; 3222. Contraction section; 3223. Transition section; 3224. Diffusion section; 322. Receiving cavity; 33. Elastic component; 331. Guide rod; 332. Forward spiral spring; 333. Reverse spiral spring; 34. Fixing sleeve; 35. Housing; 36. Spiral channel;

[0018] 37. Pressure gain structure; 371. Friction block; 372. Limiting groove;

[0019] 40. Anti-collision limiting structure; 41. Anti-collision ring; 42. Elastic partition; 43. Buffer fluid; 44. Rubber ring. Detailed Implementation

[0020] To make the technical problems, technical solutions, and beneficial effects of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the described embodiments are only a part of the embodiments of this application, not all of them. The specific embodiments described herein are only used to explain the invention and are not intended to limit the invention. Based on the embodiments in this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0021] It should be further noted that the accompanying drawings and embodiments of the present invention mainly describe the concept of the present invention. Based on this concept, some specific forms and arrangements of connection relationships, positional relationships, power mechanisms, power supply systems, hydraulic systems and control systems may not be fully described. However, under the premise that those skilled in the art understand the concept of the present invention, they can implement the above-mentioned specific forms and arrangements in a well-known manner.

[0022] When a component is referred to as being "fixed to" or "set on" another component, it can be directly on or indirectly on that other component. When a component is referred to as being "connected to" another component, it can be directly connected to or indirectly connected to that other component.

[0023] The directional terms "inner" and "outer" refer to the inner and outer contours of each component itself. The terms "length," "width," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," and "outer" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on the present invention.

[0024] The terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this invention, "a plurality of" means two or more, and "several" means one or more, unless otherwise explicitly specified.

[0025] The multi-blade adaptive PDC drill bit provided by the present invention will now be described.

[0026] The first embodiment of the present invention provides a multi-blade adaptive PDC drill bit, including a drill body 10, cutter wings 20, and an adjusting nozzle 30. The drill body 10 has a main flow channel 101 along the axial direction and a branch flow channel 102. The branch flow channel 102 extends obliquely to the surface of the drill body 10 and communicates with the main flow channel 101. One end of the drill body 10 is a threaded end 103 for connecting the drill rod, and the other end is a rock-breaking end 104. The rock-breaking end 104 has multiple circumferentially distributed liquid outlet holes 105, which communicate with the main flow channel 101. Each liquid outlet hole 105 is equipped with a common nozzle 106. Multiple cutter wings 20 are spaced apart along the circumferential direction of the rock-breaking end 104. The cutter wings 20 are connected to the rock-breaking end 104 of the drill body 10 and are equipped with a cutting structure 21. Any two adjacent cutter wings can be connected to the rock-breaking end 104. A water trough 11 is formed between the wings 20; at least one regulating nozzle 30 is embedded in the branch flow channel 102, and the regulating nozzle 30 includes a valve assembly 31, a slider 32, and an elastic member 33; the valve assembly 31 is located at one end of the branch flow channel 102 near the drill bit body 10, and is used to control the flow rate and opening degree of drilling fluid; the slider 32 is slidably disposed in the branch flow channel 102 and has sliding damping between it and the branch flow channel 102, and the slider 32 is also provided with an acceleration flow channel 321 connected to the branch flow channel 102; one end of the elastic member 33 is connected to the slider 32, and the other end is connected to the valve assembly 31, and the elastic member 33 is used to provide elastic force to drive the valve assembly 31 to extend and slide, so as to adaptively adjust the drilling fluid flow rate; the pressure required for the slider 32 to slide is greater than the pressure required for the valve assembly 31 to slide. The cutting structure 21 includes main cutting teeth 211 and secondary cutting teeth 212. The blade wing portion 20 includes a blade wing diameter-maintaining portion 201 and a blade wing crown portion 202. The blade wing crown portion 202 is provided with multiple main cutting teeth 211, and the blade wing diameter-maintaining portion 201 is provided with multiple secondary cutting teeth 212.

[0027] like Figure 1 Of Figure 6As shown, the multi-blade adaptive PDC drill bit of the present invention achieves efficient rock breaking and intelligent rock cleaning through the coordinated design of the drill bit body 10, cutter wings, and adjusting nozzle 30. The main channel 101 of the drill bit body 10 introduces drilling fluid through the connection of the drill pipe. The fluid outlet 105 of the rock breaking end 104 and the ordinary nozzle 106 form a basic flushing flow field to maintain basic cleanliness of the well bottom. Four to six cutter wings 20 are evenly distributed around the rock breaking end 104. The main cutting teeth 211 of the cutter wing crown 202 are arranged at a back slope angle of 15°-25° to break the formation through shearing action. The secondary cutting teeth 212 (diameter 8-10mm) of the cutter wing diameter-maintaining part 201 are used to trim the well wall. A water channel 11 is formed between any two adjacent cutter wings 20, extending from the rock-breaking end 104 to the cutter wing diameter-maintaining section 201. A branch flow channel 102 is provided at the bottom of the water channel 11, and an adjusting nozzle 30 is embedded in the branch flow channel 102. The adjusting nozzle 30 includes a valve assembly 31, a slider 32, and an elastic member 33. The valve assembly 31 is located at one end of the branch flow channel 102 near the drill bit body 10. Under the action of the elastic member 33, the valve assembly 31 can extend and retract along the axial direction of the branch flow channel 102. The drilling fluid flow rate varies depending on the position of the valve assembly 31. When the rock cuttings concentration at the bottom of the well exceeds 5% or the pressure increases, the adjusting nozzle 30, through the graded response of the elastic member 33 and the pressure gain structure 37, increases the local cuttings removal flow rate to 1.5-2 times the base flow rate, forming a high-speed jet to scour the rock cuttings accumulation zone between the cutter wings 20. The adjusting nozzle 30 can adaptively adjust the drilling fluid injection flow rate to assist in cuttings removal and stabilize rock breaking.

[0028] Compared with existing technologies, there are two main advantages. First, multi-blade collaborative rock breaking: the main cutting tooth 211 first contacts the formation and generates shear stress through rotation to break the rock, while the secondary cutting tooth 212 then smooths the well wall. The stepped layout of the two avoids synchronous wear. When the wear of the main tooth reaches 1.2mm, the secondary tooth fully intervenes in rock breaking. Second, intelligent rock clearing control: the ordinary nozzle 106 provides basic flushing, and the regulating nozzle 30 opens under pressure triggering. By accelerating the flow rate of the flow channel 321, and cooperating with the rotating jet generated by the spiral flow channel 36, a directional flushing is formed on the back of the cutter wing 20 and the bottom of the water tank 11, clearing the rock debris accumulation in the traditional blind zone. Furthermore, the flow distribution between the main flow channel 101 and the branch flow channel 102 is adaptively adjusted by pressure. Under basic operating conditions, 90% of the flow is sprayed through the ordinary nozzle 106, and under high-pressure operating conditions, 30%-50% of the flow is diverted to the regulating nozzle 30, realizing dynamic rock clearing of "global flushing + local enhancement". This design, through the deep integration of structural innovation and flow field optimization, breaks through the efficiency bottleneck of traditional PDC drill bits in complex formations, and is especially suitable for scenarios with stringent requirements for rock breaking and clearing, such as shale gas horizontal wells and deep wells.

[0029] like Figures 2 to 5As shown, the multi-blade adaptive PDC drill bit provided in the first embodiment of the present invention includes a fixed sleeve 34, a housing 35, and a spiral flow channel 36 in the adjusting nozzle 30. The fixed sleeve 34 is fixedly disposed in the branch flow channel 102. One end of the housing 35 is sealed to the fixed sleeve 34, and the other end is provided with a spiral flow channel 36 for drilling fluid diffusion. The slider 32 is slidably disposed in the housing 35. The center of the slider 32 is provided with an axially penetrating receiving cavity 322. The acceleration flow channel 321 is located in the slider 32 in the circumferential direction of the receiving cavity 322. The valve assembly 31 is slidably connected to the receiving cavity 322 so that in one sliding position, one end of the valve assembly 31 is sealed to the inlet of the spiral flow channel 36, and in another sliding position, one end of the valve assembly 31 is opened to the inlet of the spiral flow channel 36.

[0030] The fixed sleeve 34 is fixedly installed inside the branch flow channel 102 to determine the specific position of the regulating nozzle 30 within the branch flow channel 102. One end of the housing 35 is threadedly sealed to the fixed sleeve 34, and the other end is provided with a spiral flow channel 36 for drilling fluid diffusion. The slider 32 is slidably installed inside the housing 35. At least one acceleration flow channel 321 is provided in the circumferential direction of the slider 32. In this design, there are two acceleration flow channels 321. An axially penetrating receiving cavity 322 is provided at the center of the slider 32. An elastic member 33 is provided inside the receiving cavity 322. The second end of the elastic member 33 is connected to the valve assembly 31. The other end of the valve assembly 31 is sealed to the inlet of the spiral flow channel 36. The elastic member 33 is used to provide elastic force to drive the valve assembly 31 to slide and adaptively adjust the drilling fluid flow rate. When the drilling fluid pressure suddenly increases, the pressure first pushes the valve assembly 31 to slide and quickly release the pressure. When the pressure continues to act and reaches a higher threshold, it drives the slider 32 to slide. The pressure required for the slider 32 to slide is greater than the pressure required for the valve assembly 31 to slide.

[0031] When the bottom hole pressure suddenly increases, the drilling fluid directly impacts the valve assembly 31 through the acceleration channel 321, generating axial thrust. The valve assembly 31 overcomes the elastic force of the elastic member 33 and separates from the inlet of the spiral channel 36, forming an annular gap to achieve rapid pressure relief. At this time, the slider 32 remains stationary because the frictional resistance of the pressure gain structure 37 is greater than the pressure. When the pressure continues to rise to the threshold, the sum of the fluid thrust and the end face pressure of the slider 32 exceeds the total stiffness of the elastic member 33 and the frictional resistance, and the slider 32 begins to move. The inlet of the spiral channel 36 is fully open, and the drilling fluid forms a rotating jet through the spiral channel 36. The rotating jet generated by the spiral channel 36 forms a centrifugal force field, which expands the cuttings removal radius by 1.5 times, achieving full-flow flushing and improving the cuttings removal efficiency by 60%.

[0032] This design, through the synergistic effect of mechanical friction and fluid mechanics, breaks through the traditional single mode of "fully closed-fully open" nozzles and realizes intelligent switching between "slightly open for pressure relief and fully open for rock removal". It is particularly suitable for complex working conditions with large formation pressure fluctuations (such as shale gas horizontal wells), and improves drill bit footage efficiency by more than 25%.

[0033] like Figure 3 As shown, the multi-blade adaptive PDC drill bit provided in the first embodiment of the present invention has an acceleration channel 321 comprising an inlet section 3221, a contraction section 3222, a transition section 3223, and a diffusion section 3224 connected in sequence. The inlet section 3221 is a circular tube structure, with one end connected to the fixed casing 34 for introducing drilling fluid. The contraction section 3222 is a conical structure, with its large-diameter end connected to the other end of the inlet section 3221, and its small-diameter end facing the transition section 3223. The cone angle of the converging section 3222 is α; the transition section 3223 is a circular tube structure, one end of which is connected to the small-diameter end of the converging section 3222, and the other end of which is connected to the diffuser section 3224. The diameter ratio of the transition section 3223 to the inlet section 3221 is 0.35-0.6; the diffuser section 3224 is a conical structure, with its small-diameter end connected to the other end of the transition section 3223. The large-diameter end of the diffuser section 3224 faces the spiral flow channel 36, and the cone angle of the diffuser section 3224 is β, where α > β.

[0034] Drilling fluid flows smoothly into the inlet section 3221. In the contraction section 3222, the cross-sectional area decreases sharply, converting static pressure energy into kinetic energy, forming a high-speed jet. The transition section 3223, with its constant channel diameter, reduces turbulent energy loss through flow stabilization. The diffusion section 3224, with its gradually expanding cross-sectional area, converts some kinetic energy into static pressure energy, creating a composite flow field of "high-speed impact + stable pressurization." Finally, it is injected into the spiral channel 36 at high velocity and high pressure, driving the valve head 313 to actuate. Furthermore, the acceleration channel 321 has strong anti-clogging capabilities, and the large cone angle design of the contraction section 3222 and the diffusion section 3224 reduces the risk of cuttings retention. Combined with the flow stabilization effect of the transition section 3223, it can pass cuttings particles with a diameter of up to 3mm, making it suitable for drilling fluid environments with high solids content.

[0035] like Figure 5As shown, the multi-blade adaptive PDC drill bit provided in the first embodiment of the present invention includes a valve assembly 31 comprising a valve seat 311, a valve stem 312, and a valve head 313. The valve seat 311 is slidably disposed within the receiving cavity 322, and the second end of the elastic member 33 is connected to the valve seat 311. The first end of the valve stem 312 is fixedly connected to the center of the valve seat 311, and the second end extends to the spiral flow channel 36. The valve head 313 has an inverted conical structure and is fixed to the second end of the valve stem 312. The valve head 313 is sealed to the inlet of the spiral flow channel 36. When the valve assembly 31 slides, the valve head 313 disengages from or adheres to the sealing surface, controlling the flow rate and opening degree of the drilling fluid.

[0036] Valve assembly 31 achieves precise control of drilling fluid flow rate through a linkage structure of valve seat 311, valve stem 312, and valve head 313. Specifically, valve seat 311 is nested within the receiving cavity 322 of slider 32, and the second end of elastic member 33 abuts against valve seat 311, providing initial preload. The first end of valve stem 312 is fixedly connected to the center of valve seat 311, and the second end of valve stem 312 extends to the inlet of spiral flow channel 36. Inverted conical valve head 313 is fixedly installed at the end of valve stem 312, forming a line contact seal with the conical sealing surface of spiral flow channel 36 inlet. When drilling fluid is accelerated through acceleration channel 321 (including contraction section 3222 and diffusion section 3224), the high-speed fluid directly impacts the inverted conical surface of valve head 313, generating axial thrust. The thrust is transmitted from the valve head 313 to the valve seat 311 via the valve stem 312. After overcoming the preload of the elastic member 33, it drives the valve seat 311 and the elastic member 33 to move axially synchronously, causing the valve head 313 to disengage from the sealing surface of the spiral flow channel 36 inlet and open the flow channel.

[0037] In a static state, the preload of the elastic component 33 ensures that the valve head 313 is tightly fitted against the sealing surface. When the fluid thrust exceeds the preload, the valve head 313 gradually separates from the sealing surface, and the flow channel opening increases linearly with the displacement of the valve head 313. When the pressure decreases, the elastic component 33 releases its stored energy, pushing the valve seat 311-valve stem 312-valve head 313 assembly to move in the opposite direction. The inverted conical surface of the valve head 313 re-embeds into the sealing surface, achieving precise reset by utilizing the automatic centering characteristic of the conical surface fit. This valve assembly 31 adopts a design concept of "direct pressure bearing of the valve head 313 + mechanical rigid linkage + elastic dynamic balance," solving the technical problems of slow response, low accuracy, and easy erosion of traditional valve assemblies 31, and providing core support for efficient rock clearing of PDC drill bits in complex formations.

[0038] like Figure 5As shown, the multi-blade adaptive PDC drill bit provided in the first embodiment of the present invention includes an elastic component 33 comprising a guide rod 331, a forward spiral spring 332, and a reverse spiral spring. The guide rod 331 is disposed in the receiving cavity 322. A fastener is provided at the first end of the guide rod 331 after penetrating the bottom wall of the receiving cavity 322. The second end of the guide rod 331 is slidably connected to the valve seat 311. The reverse spiral spring 333 is sleeved on the guide rod 331, and the forward spiral spring 332 is sleeved outside the reverse spiral spring 333. Both the forward spiral spring 332 and the reverse spiral spring 333 are connected at one end to the valve seat 311 and at the other end to the bottom wall of the receiving cavity 322. In the working state, the forward spiral spring 332 is in a stretched state, while the reverse spiral spring 333 is in a compressed state. The valve head 313 is sealed and abuts against the inlet of the spiral flow channel 36 with the cooperation of the forward spiral spring 332 and the reverse spiral spring 333.

[0039] In this invention, the elastic forces of the forward-rotating spring 332 and the reverse-rotating spring 333 work synergistically to achieve a reliable sealing fit between the valve head 313 and the inlet of the spiral flow channel 36. Specifically, the elastic component 33 adopts a combined structure of "guide rod 331 + forward-rotating spring 332 + reverse-rotating spring 333". The guide rod 331 is axially arranged along the receiving cavity 322. Its first end penetrates the bottom wall of the receiving cavity 322 and is fixed with a circular fastener (such as a limit nut) by thread or welding to limit the axial displacement of the guide rod 331. The second end is a smooth cylindrical surface. The second end of the guide rod 331 forms a clearance fit with the guide hole in the center of the valve seat 311, allowing the valve seat 311 to slide freely along the guide rod 331. A counter-rotating spring 333 is sleeved outside the guide rod 331, with one end abutting against the valve seat 311 and the other end abutting against the bottom wall of the receiving cavity 322. A forward-rotating spring 332 is sleeved outside the counter-rotating spring 333, with one end connected to the valve seat 311 and the other end fixed to the bottom wall of the receiving cavity 322. In operation, the forward-rotating spring 332 is always in a pre-tensioned state, providing a tensile force F1 in the direction close to the receiving cavity 322; the counter-rotating spring 333 is in a pre-compressed state, providing a thrust F2 in the direction away from the receiving cavity 322. When there is no drilling fluid pressure, the resultant force of F1 and F2 makes the inverted conical sealing surface of the valve head 313 fit tightly against the conical surface of the inlet of the spiral flow channel 36, forming an initial seal. This design brings dual technical advantages: First, the elastic forces of the forward and counter-rotating springs 333 are in opposite directions. When the downhole temperature rises and causes the spring material to expand thermally, the changing trends of F1 and F2 cancel each other out. Testing showed that, under a high-temperature environment of 150℃, the fluctuation range of the elastic force difference between F1 and F2 was less than 5%, far lower than the 20% fluctuation of a single-spring structure, ensuring stable response of the valve head 313 under high pressure differential conditions. Secondly, the dual-spring structure balances the force on the valve seat 311 through pre-load, keeping the overall deformation within a small range of 0.5-1.0mm. During installation, simply adjusting the axial position of the guide rod 331 with fasteners simultaneously sets the pre-tightening force of the dual springs, eliminating the need for complex pressure adjustment procedures and meeting the rapid assembly requirements of drilling sites. This structure is particularly suitable for high-temperature and high-pressure formations. Through the mechanical coupling effect of the dual springs, it ensures the sensitive response of the valve head 313 to changes in drilling fluid pressure, improves the reliability of the elastic component 33 in extreme environments, and extends the service life of the adjusting nozzle 30. A sealing element is provided between the valve seat 311 and the receiving cavity 322. The sealing element can be an O-ring, embedded in the sealing groove circumferentially provided in the valve seat 311 to achieve radial sealing.

[0040] like Figures 3 to 5As shown, the multi-blade adaptive PDC drill bit provided in the first embodiment of the present invention includes a pressure gain structure 37 in the adjusting nozzle 30. The pressure gain structure 37 includes a friction block 371 and a limiting groove 372. The friction block 371 is disposed on the inner wall of the housing 35 along the axial direction, and friction ridges are provided on the surface of the friction block 371. The limiting groove 372 is disposed on the outer circumferential surface of the slider 32 and is adapted to the friction block 371. The limiting groove 372 and the inner wall of the limiting groove 372 are provided with a high friction coefficient coating. By increasing the friction of the contact surface, the sliding pressure of the slider 32 is greater than the sliding pressure of the valve head 313.

[0041] The pressure gain structure 37 achieves a graded response mechanism of "low-pressure valve opening and pressure relief, high-pressure slider 32 linkage" through friction pair design. Specifically, a cuboid friction block 371 is axially arranged on the inner wall of the housing 35, and the surface of the friction block 371 is machined with trapezoidal friction ridges; the outer circumferential surface of the slider 32 is correspondingly provided with a rectangular limiting groove 372 adapted to the friction block 371, and the inner wall of the limiting groove 372 is sprayed with a nickel-based tungsten carbide high-friction coating, forming a mechanical resistance interface between the friction block 371 and the inner wall of the limiting groove 372. When the bottom hole pressure suddenly rises, a small pressure can push the valve head 313 to overcome the pre-tightening force of the elastic component 33 and open quickly, achieving first-level pressure relief and avoiding the impact of high pressure on the drill bit structure; when the pressure continues to rise to a set threshold, the coating of the friction block 371 and the limiting groove 372 are in close contact, and the meshing resistance between the ridges and the coating forces the slider 32 to slide synchronously, triggering the second-level full-flow scouring. At this time, the opening of the valve head 313 and the displacement of the slider 32 increase synergistically, achieving a large amount of pressure relief while enhancing the rock clearing effect.

[0042] The beneficial effects of this design include: ① The mechanical resistance of the friction pair precisely sets the pressure difference between the valve head 313 and the slider 32, ensuring that only the valve head 313 opens quickly to release pressure during small pressure fluctuations, avoiding the waste of hydraulic energy caused by accidental full-flow flushing; ② When the pressure is low, the valve head 313 releases pressure with a small opening, maintaining basic cleanliness at the bottom of the well; when the pressure exceeds the threshold, the slider 32 increases the flow rate in conjunction, forming a high-speed jet to flush the rock cuttings accumulation area, improving the rock cleaning efficiency by more than 40% compared to the traditional single-stage structure; ③ The design of the valve head 313 acting before the slider 32 can release 30%-50% of the impact energy at the moment of pressure change (<0.1s), reducing the impact load of high pressure on the internal structure of the drill bit and extending the life of the seals and elastic components 33;

[0043] like Figure 4As shown, the multi-blade adaptive PDC drill bit provided in the first embodiment of the present invention has anti-collision limiting structures 40 at both ends of the slider 32. The anti-collision limiting structure 40 includes an anti-collision ring 41, an elastic partition 42, a buffer fluid 43, and a rubber ring 44. The anti-collision ring 41 is disposed at the end of the slider 32 and has a cavity structure. The elastic partition 42 is disposed inside the anti-collision ring 41, dividing the anti-collision ring 41 into a first cavity and a second cavity. The buffer fluid 43 is disposed in the first cavity and is a viscous fluid. The rubber ring 44 is disposed in the second cavity.

[0044] The anti-collision ring 41 is made of shape memory alloy, which is elastic and compressible. The anti-collision ring 41 has a hollow internal structure, and its inner wall is provided with an elastic partition 42. The elastic partition 42 is integrally formed with the anti-collision ring 41, and the elastic partition 42 divides the interior of the anti-collision ring 41 into a first compartment and a second compartment. The first compartment is filled with a shear buffer fluid 43 (such as a silicone oil-based non-Newtonian fluid), and the second compartment is fitted with a rubber ring 44. This anti-collision limiting structure 40 can limit the excessive movement of the slider 32 and prevent the valve head 313 from opening excessively. The rubber ring 44 provides initial buffering, and then the buffer fluid 43 flows under pressure to achieve secondary damping. At the same time, the rubber ring 44 acts as a seal in the second compartment to prevent drilling fluid from entering. When the impact load disappears, the elastic force of the elastic partition 42 and the rubber ring 44 pushes the slider 32 to reset, ensuring that it returns to its initial position. This anti-collision limiting structure 40 takes into account the functions of limiting, buffering, sealing and resetting, improving the reliability of the regulating nozzle 30 under high-pressure impact conditions.

[0045] The above are merely preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention are permitted.

Claims

1. A multi-blade adaptive PDC drill bit, characterized in that, include: The drill bit body (10) has a main channel (101) along the axial direction and a branch channel (102). The branch channel (102) extends obliquely to the surface of the drill bit body (10) and communicates with the main channel (101). One end of the drill bit body (10) is a threaded end (103) for connecting the drill rod, and the other end is a rock-breaking end (104). The rock-breaking end (104) has multiple liquid outlet holes (105) distributed circumferentially. The liquid outlet holes (105) communicate with the main channel (101). Each liquid outlet hole (105) is equipped with a common nozzle (106). Multiple blade wings (20) are arranged at intervals along the circumferential direction of the rock-breaking end (104). The blade wings (20) are connected to the rock-breaking end (104) of the drill bit body (10) and are equipped with a cutting structure (21). A water groove (11) is formed between any two adjacent blade wings (20). At least one regulating nozzle (30) is embedded in the branch flow channel (102); The adjusting nozzle (30) includes: A valve assembly (31) is disposed at one end of the branch flow channel (102) near the drill bit body (10) for controlling the flow rate and opening degree of drilling fluid; The slider (32) is slidably disposed within the branch channel (102) and has sliding damping between it and the branch channel (102); The elastic member (33) is connected at one end to the slider (32) and at the other end to the valve assembly (31). The elastic member (33) is used to provide elastic force to drive the valve assembly (31) to extend and slide, so as to adaptively adjust the drilling fluid flow rate. The pressure required for the slider (32) to slide is greater than the pressure required for the valve assembly (31) to slide; The regulating nozzle (30) also includes a fixed sleeve (34) and a housing (35). The fixed sleeve (34) is fixedly installed inside the branch flow channel (102). One end of the housing (35) is sealed to the fixed sleeve (34), and the other end is provided with a spiral flow channel (36), which is used for drilling fluid diffusion. The slider (32) is slidably disposed in the housing (35), and the center of the slider (32) is provided with an axially penetrating receiving cavity (322). The acceleration channel (321) is located in the slider (32) in the circumferential direction of the receiving cavity (322). The valve assembly (31) is slidably connected to the receiving cavity (322) so that in one sliding position, one end of the valve assembly (31) is sealed to the inlet of the spiral channel (36), and in another sliding position, one end of the valve assembly (31) is opened to the inlet of the spiral channel (36). The acceleration channel (321) includes an inlet section (3221), a contraction section (3222), a transition section (3223), and a diffusion section (3224) connected in sequence. The inlet section (3221) is a circular tube structure, and one end of the inlet section (3221) is connected to the fixed casing (34) for introducing drilling fluid; The contraction section (3222) is a conical structure. The large-diameter end of the contraction section (3222) is connected to the other end of the inlet section (3221). The small-diameter end of the contraction section (3222) faces the transition section (3223), and the cone angle of the conical section (3222) is α. The transition section (3223) is a circular tube structure. One end of the transition section (3223) is connected to the small-diameter end of the contraction section (3222), and the other end of the transition section (3223) is connected to the diffusion section (3224). The diameter ratio of the transition section (3223) to the diameter of the inlet section (3221) is 0.35-0.

6. The diffuser section (3224) is a conical structure, with its small-diameter end connected to the other end of the transition section (3223). The large-diameter end of the diffuser section (3224) faces the spiral flow channel (36), and the cone angle of the diffuser section (3224) cone is β, where α > β. The valve assembly (31) includes: A valve seat (311) is slidably disposed within the receiving cavity (322), and the second end of the elastic member (33) is connected to the valve seat (311); The valve stem (312) is fixedly connected at one end to the center of the valve seat (311), and the other end extends to the spiral flow channel (36); The valve head (313) has an inverted conical structure and is fixed to the second end of the valve stem (312). The valve head (313) is sealed to the inlet of the spiral flow channel (36). When the valve assembly (31) slides, the valve head (313) disengages from or engages with the sealing surface, controlling the flow and opening degree of the drilling fluid. The elastic component (33) includes a guide rod (331), a clockwise spring (332), and a counterclockwise spring (333). The guide rod (331) is disposed inside the receiving cavity (322). The first end of the guide rod (331) passes through the bottom wall of the receiving cavity (322) and is provided with a fastener. The second end of the guide rod (331) is slidably connected to the valve seat (311). The counterclockwise spring (333) is sleeved on the guide rod (331). The clockwise spring (332) is sleeved outside the counterclockwise spring (333). Both the clockwise spring (332) and the counterclockwise spring (333) are connected at one end to the valve seat (311) and at the other end to the bottom wall of the receiving cavity (322). The regulating nozzle (30) further includes a pressure gain structure (37), which includes: Friction block (371) is disposed on the inner wall of the housing (35) along the axial direction, and friction ridges are provided on the surface of the friction block (371); The limiting groove (372) is provided on the outer surface of the slider (32) and is adapted to the friction block (371). The limiting groove (372) and the inner wall of the limiting groove (372) are provided with a high friction coefficient coating. By increasing the friction of the contact surface, the sliding pressure of the slider (32) is greater than the sliding pressure of the valve head (313).

2. The multi-blade adaptive PDC drill bit as described in claim 1, characterized in that, The cutting structure (21) includes main cutting teeth (211) and secondary cutting teeth (212). The blade wing (20) includes a blade wing diameter-preserving part (201) and a blade wing crown part (202). The blade wing crown part (202) is provided with multiple main cutting teeth (211), and the blade wing diameter-preserving part (201) is provided with multiple secondary cutting teeth (212).

3. The multi-blade adaptive PDC drill bit as described in claim 1, characterized in that, A seal is provided between the valve seat (311) and the receiving cavity (322).

4. The multi-blade adaptive PDC drill bit as described in claim 1, characterized in that, The slider (32) is provided with anti-collision limiting structures (40) at both ends, and the anti-collision limiting structures (40) include: An anti-collision ring (41) is disposed at the end of the slider (32), and the anti-collision ring (41) has a hollow structure; An elastic partition (42) is disposed inside the anti-collision ring (41) to divide the anti-collision ring (41) into a first compartment and a second compartment; A buffer fluid (43) is disposed in the first cavity, and the buffer fluid (43) is a viscous fluid; A rubber ring (44) is disposed in the second cavity.

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