Pulse negative pressure suction PDC drill bit

Abstract

This invention discloses a pulsed negative pressure suction PDC drill bit, relating to the field of oil, gas, and geological drilling tools. The PDC drill bit includes a drill bit body and a flow channel assembly. The drill bit body includes a working end and a connecting end. The flow channel assembly includes a central flow channel axially disposed within the drill bit body, several forward flow channels connected to the bottom of the central flow channel and arranged circumferentially, and several reverse flow channels connected to the middle of the central flow channel and arranged circumferentially. The outlet end of the forward flow channels is located at the working end of the drill bit body to form a first pressure between the working end of the drill bit body and the bottom wall of the borehole. The outlet end of the reverse flow channels is located in the middle of the drill bit body, and the number of reverse flow channels is less than the number of forward flow channels to form a second pressure less than the first pressure in the annulus of the drill bit body. This application can improve cuttings return efficiency, reduce repeated breaking, reduce the bottom hole rock holding effect, and improve rock breaking efficiency.

Description

Technical Field

[0001] This invention relates to the field of oil, natural gas and geological drilling tools, and specifically to a pulse negative pressure suction PDC drill bit. Background Technology

[0002] PDC (Polycrystalline Diamond Compact) drill bits mainly consist of the drill bit body, connector, cutting structure, and hydraulic structure. In actual drilling operations, these drill bits often face the following key problem: During drilling, the wellbore fluid column pressure is usually higher than the formation pressure, resulting in confining pressure at the bottom of the well. This confining pressure holds the rock cuttings generated by the drill bit at the bottom of the well, hindering cuttings removal and leading to repeated cutting. This problem directly causes a significant decrease in the drill bit's rock-breaking efficiency, especially when using high-density drilling fluids. Summary of the Invention

[0003] This application provides a pulse negative pressure suction PDC drill bit, which can solve the technical problem in the prior art where, during the drilling process, the fluid column pressure in the wellbore is usually higher than the formation pressure, resulting in a confining pressure at the bottom of the well. This confining pressure will hold the rock cuttings generated by the drill bit at the bottom of the well, hindering the removal of rock cuttings and causing a significant decrease in the rock breaking efficiency of the drill bit.

[0004] This application provides a pulse negative pressure suction PDC drill bit, characterized in that it includes: The drill bit body includes a working end for drilling and a docking end for connecting to an external power component; The flow channel assembly includes a central flow channel axially disposed within the drill bit body, a plurality of forward flow channels circumferentially arranged and connected to the bottom of the central flow channel, and a plurality of reverse flow channels circumferentially arranged and connected to the middle of the central flow channel. The outlet end of the forward flow channel is located at the working end of the drill bit body to form a first pressure between the working end of the drill bit body and the bottom wall of the borehole. The outlet end of the reverse flow channel is located at the middle of the drill bit body, and the number of reverse flow channels is less than the number of forward flow channels to form a second pressure less than the first pressure in the annulus of the drill bit body.

[0005] In one embodiment, the drill bit body includes a shank, one end of which is provided with a plurality of blades circumferentially to form a working end, and the other end of which is provided with an external thread to form a mating end.

[0006] In one embodiment, two adjacent blades form a chip removal groove.

[0007] In one embodiment, one end of the blade is located at the center of the handle, and the other end spreads radially along the handle. The blade forms an inner cone section, a nose shoulder section, and a diameter-maintaining section in sequence in a direction that gradually moves away from the center of the handle, and cutting teeth are provided on the inner cone section, the nose shoulder section, and the diameter-maintaining section.

[0008] In one embodiment, the central flow channel is axially disposed at the center of the handle, with one end of the central flow channel passing through the docking end and the other end connected to the forward flow channel.

[0009] In one embodiment, a plurality of the forward flow channel inlet ends converge at the center of the handle to connect to the central flow channel, the outlet end of the forward flow channel diffuses radially along the handle, the outlet end of the forward flow channel is located in the chip removal groove, and the outlet end of the forward flow channel is provided with a surface nozzle.

[0010] In one embodiment, the inlet end of the reverse flow channel is connected to the middle of the central flow channel, the outlet end of the reverse flow channel is located at the chip removal groove, and the outlet end of the reverse flow channel is higher than the outlet end of the forward flow channel.

[0011] In one embodiment, the outlet end of the reverse flow channel is located in the diameter-maintaining section of the blade.

[0012] In one embodiment, the outlet end of the reverse flow channel is located in the middle of the handle.

[0013] In one embodiment, the outlet end of the reverse flow channel is provided with a pulse nozzle.

[0014] The beneficial effects of the technical solutions provided in this application include: 1. The first pressure is formed at the bottom of the well through the forward flow channel and the second pressure is formed in the annulus through the reverse flow channel. A negative pressure environment is established between the working end and the annulus, which makes it easier for rock cuttings to be stripped from the bottom of the well and carried away under the pressure difference. This significantly reduces repeated cutting, directly increases the mechanical drilling rate, improves the efficiency of rock cuttings return, reduces repeated crushing, and at the same time reduces the rock holding effect at the bottom of the well to improve rock breaking efficiency. 2. The reverse pulse flow generated by the reverse flow channel can exert a holding effect on the rock at the bottom of the well, reduce repeated cutting and improve the rock breaking efficiency of the cutting teeth, and reduce drilling operation costs; 3. The reverse flow channel can divert drilling fluid at the bottom of the well, avoiding excessive jet velocity caused by concentrated drilling fluid injection, effectively reducing the risk of erosion of the drill bit body and cutting teeth, reducing tooth loss, and further extending the service life of the drill bit. 4. The number of forward and reverse flow channels can be flexibly set according to actual drilling needs, and the nozzle spray angle is optimized to adapt to various scenarios such as oil and gas exploration and geological drilling, and has broad application prospects. Attached Figure Description

[0015] To more clearly illustrate the technical solutions in the embodiments of this application, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0016] Figure 1 A cross-sectional view of a pulse negative pressure suction PDC drill bit provided in an embodiment of this application; Figure 2 A cross-sectional view of the drill bit body in a pulse negative pressure suction PDC drill bit provided in an embodiment of this application; Figure 3 A schematic diagram of the nozzle structure on the mid-surface of a pulse negative pressure suction PDC drill bit provided in this application embodiment; Figure 4 This is a schematic diagram of a first embodiment of the reverse flow channel in a pulse negative pressure suction PDC drill bit provided in this application. Figure 5 This is a schematic diagram of a third embodiment of the reverse flow channel in a pulse negative pressure suction PDC drill bit provided in this application. Figure 6 This is a schematic diagram of the pulse nozzle structure in a pulse negative pressure suction PDC drill bit provided in an embodiment of this application.

[0017] In the figure: 1. Drill bit body; 101. Shank; 102. Cutting blade; 103. Chip removal groove; 104. Cutting teeth; 2. Central flow channel; 3. Forward flow channel; 4. Reverse flow channel; 5. Face nozzle; 501. First water inlet; 502. First connecting thread; 503. First water outlet; 504. First loading and unloading part; 6. Pulse nozzle; 601. Second water inlet; 602. Self-excited oscillation chamber; 603. Second loading and unloading part; 604. Second water outlet; 605. Second connecting thread. Detailed Implementation

[0018] To enable those skilled in the art to better understand the present application, the technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present application, and not all embodiments. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present application.

[0019] This application provides a pulse negative pressure suction PDC drill bit, which can solve the technical problem in the prior art where, during the drilling process, the wellbore fluid column pressure is usually higher than the formation pressure, resulting in confining pressure at the bottom of the well. This confining pressure will hold the rock cuttings generated by the drill bit at the bottom of the well, hindering the removal of rock cuttings and causing a significant decrease in the rock breaking efficiency of the drill bit.

[0020] The pulse negative pressure suction PDC drill bit of this application includes a drill bit body 1 and a flow channel assembly formed within the drill bit body 1. Figure 1 A cross-sectional view of a pulse negative pressure suction PDC drill bit provided for an embodiment of this application, such as... Figure 1 As shown, the drill bit body 1 includes a working end for drilling and a docking end for connecting with external power components. It efficiently breaks deep rocks by shearing or crushing, and relies on high-speed drilling fluid injected by internal nozzles to cool, clean and assist in rock breaking. The docking end is used to connect with external drill strings, thereby transmitting the torque, drilling pressure and circulating drilling fluid provided by the surface drive system to the working end.

[0021] Furthermore, the flow channel assembly includes a central flow channel 2, a forward flow channel 3, and a reverse flow channel 4. The number of central flow channels 2 is one, which is arranged along the axial direction of the drill bit body 1 at the center of the drill bit body 1 and can guide drilling fluid into the drill bit body 1.

[0022] There are multiple forward flow channels 3, which are arranged radially and circumferentially along the drill bit body 1. The forward flow channels 3 are set inside the drill bit body 1 so that their inlet end connects to the bottom of the central flow channel 2 facing the working end, and their outlet end extends to the working end face of the drill bit body 1. Based on this structure, the drilling fluid can be directly sprayed through the central flow channel 2 and the forward flow channels 3 to the working end of the drill bit body 1 and the bottom wall of the borehole. When the drilling fluid is sprayed out, it will encounter the obstruction of the bottom wall of the borehole and the restriction of the narrow annular gap. When the high-speed flowing fluid encounters an obstacle or a sudden change in space, its kinetic energy will be partially converted into pressure energy. At the same time, the drilling fluid is continuously pumped in and rapidly accumulates and is restricted in the limited space between the drill bit end face and the bottom of the hole, and cannot be dispersed instantly, thereby generating the first pressure in this closed area.

[0023] There are also multiple reverse flow channels 4, which are arranged radially and circumferentially along the drill bit body 1. The inlet end of the reverse flow channel 4 is connected to the middle of the central flow channel 2, and the outlet end extends above the outlet end of the forward flow channel 3. That is to say, the overall position of the reverse flow channel 4 is higher than that of the forward flow channel 3, and the number of reverse flow channels 4 is less than that of the forward flow channel 3. This allows most of the drilling fluid in the central flow channel 2 to be ejected from the forward flow channel 3 to the bottom of the well, and a small portion to be ejected from the reverse flow channel 4 to the well wall. Based on this structure, the drilling fluid ejected from the reverse flow channel 4 can form a second pressure less than the first pressure in the annulus between the outer cylindrical surface of the drill bit body 1 and the well wall. The pressure difference between the first pressure and the second pressure can form a negative pressure at the bottom of the well and generate pulse suction, effectively solving the problem of poor cuttings removal in traditional drill bits, reducing cuttings accumulation, reducing the risk of stuck drill bit and mud bag, and ensuring the continuity of drilling operations. In one possible implementation, the number of forward flow channels 3 is at least two, and the number of reverse flow channels 4 is at least one.

[0024] Furthermore, Figure 2 A cross-sectional view of the drill bit body 1 in a pulse negative pressure suction PDC drill bit provided in this application embodiment, as shown below. Figure 2 As shown, the drill bit body 1 includes a shank 101. Multiple blades 102 are circumferentially arranged on the outer periphery of one end of the shank 101 to form the working end. An external thread is provided at the other end of the shank 101 to form the mating end. The core skeleton and support body of the shank 101 are typically high-strength alloy steel forgings. Multiple raised blades 102 are circumferentially and radially welded or integrally machined on the outer periphery of one end of the shank 101. A standard external thread is machined at the other end of the shank 101, connecting with the internal thread of the drill collar at the lowest point of the drill string. This is the only interface for mechanical and hydraulic transmission between the drill bit and the entire drilling power system, responsible for transmitting torque, drilling pressure, and high-pressure drilling fluid.

[0025] Further details can be found here. Figure 2 Between two adjacent blades 102, a low-lying, spiral or straight channel, namely the chip removal channel 103, will be naturally formed. The high-pressure drilling fluid rushes to the bottom of the well through the forward flow channel 3. After completing the tasks of cooling the cutting teeth 104, assisting in rock breaking and cleaning the bottom of the well, the ejected drilling fluid will carry the broken rock cuttings and return to the surface through the chip removal channel 103 along the annulus between the drill bit body 1 and the well wall.

[0026] Further details can be found here. Figure 2One end of the cutter wing 102 is located at the center of the shank 101, and the other end spreads radially along the shank 101. The cutter wing 102 forms an inner cone section, a nose shoulder section, and a gauge-maintaining section in sequence in the direction gradually moving away from the center of the shank 101. Each of the inner cone section, nose shoulder section, and gauge-maintaining section is equipped with cutting teeth 104, which are PDC composite plates. The inner cone section is located at the beginning of the cutter wing 102 closest to the central axis of the drill bit body 1. It is responsible for "eating" the rock at the beginning of drilling to form an initial guide hole. The nose shoulder section is the arc-shaped transition area of ​​the cutter wing 102 that extends outward from the center. It is also the part that undertakes the most important rock-breaking task. The cutting teeth 104 here have the highest linear velocity and are subjected to complex forces, so the wear is also the most severe. It is the key to the entire life of the drill bit. The gauge-maintaining section is located at the outermost edge of the cutter wing 102, close to the drilled well wall. It is mainly used to trim the well wall to the standard size and provide lateral support for the drill bit body 1 to prevent uneven wear and wellbore deviation, and ensure well quality. The cutting teeth 104 can be made of commonly used materials such as polycrystalline diamond composite sheets, and no specific restrictions are imposed here.

[0027] Further details can be found here. Figure 1 The central flow channel 2 is axially located at the center of the shank 101, with one end of the central flow channel 2 passing through the docking end and the other end connected to the forward flow channel 3. That is, the axial length of the central flow channel 2 is less than the axial length of the shank 101. The inlet end at the top of the central flow channel 2 is connected to the drill rod, and the outlet end at the bottom of the central flow channel 2 is located inside the drill bit body 1 and connected to the forward channel.

[0028] Further details can be found here. Figure 1 The inlet ends of each forward flow channel 3 converge at the center of the shank 101 to connect with the central flow channel 2. The outlet ends of the forward flow channels 3 diffuse radially along the shank 101, i.e., the forward flow channels 3 are inclined. Multiple forward flow channels 3 form a trumpet shape to ensure that the high-pressure drilling fluid coming down from the single central flow channel 2 can be evenly and unbiasedly distributed to each forward flow channel 3 leading to different blades 102. The forward flow channels 3 follow the direction of the blades 102 to directly and accurately deliver the drilling fluid to the corresponding blades 102, ensuring that each blade 102 and each cutting tooth 104 can obtain equal and timely cooling and cleaning. The outlet end of the forward flow channel 3 is located in the chip removal groove 103, which can directly flush the cutting teeth 104 and the rock cuttings in front of the teeth to remove the rock cuttings on the cutting surface of the blades 102 in the first time, preventing them from accumulating and re-entering the cutting zone. At the same time, it assists in breaking rocks and picks up rock cuttings from the bottom of the well.

[0029] Further details can be found here. Figure 1 The outflow end of the forward flow channel 3 is equipped with a face nozzle 5. The face nozzle 5 can convert the pressure energy of the high-pressure drilling fluid into high-speed, concentrated jet kinetic energy. At the same time, the flow channel cross section of the face nozzle 5 shrinks sharply, which can greatly increase the fluid velocity of the drilling fluid and form a high-speed, high-impact jet.

[0030] In one possible implementation, the angle α between the face nozzle 5 and the central axis of the shank 101 of the drill bit body 1 satisfies: 0°≤α≤45°, and the flow channel diameter is 5mm~25mm. The spray angle of the face nozzle 5 at different positions varies according to the actual situation, ensuring that the impact energy of the drilling fluid is used to the maximum extent for the most critical bottom hole and cutting area, achieving the best balance between core functions such as direct rock breaking, cleaning tooth surface, preventing mud packing and cooling cutting teeth 104.

[0031] Furthermore, Figure 3 This application provides a schematic diagram of the structure of the nozzle 5 on the mid-surface of a pulse negative pressure suction PDC drill bit, as shown in the embodiment. Figure 3 As shown, in one possible implementation, the face nozzle 5 mainly includes a first water inlet 501, a first connecting thread 502, a first water outlet 503, and a first loading and unloading part 504. Its features are that it uses a hard alloy with high hardness and high wear resistance as the base material, combined with an optimized flow channel design, to achieve anti-erosion, low energy consumption and strong cleaning / assisted rock breaking functions, and is suitable for various drilling conditions.

[0032] Furthermore, based on the different specifications of the drill bit body 1, the reverse flow channel 4 in this application has three implementation methods. Figure 4 This application provides a schematic diagram of a first embodiment of the reverse flow channel 4 in a pulse negative pressure suction PDC drill bit, as shown in the following example. Figure 4 As shown, in the first embodiment, the inlet end of the reverse flow channel 4 is connected to the middle of the central flow channel 2, and the outlet end of the reverse flow channel 4 extends to the chip removal groove 103 near the shank 101. In this embodiment, the outlet end of the reverse flow channel 4 is higher than the outlet end of the forward flow channel 3. This embodiment is suitable for drill bit bodies 1 with larger dimensions, especially drill bit bodies 1 between 14” and 26”, which can shorten the distance between the drill bit body and the bottom of the well to better form negative pressure.

[0033] Further details can be found here. Figure 1 In the second embodiment, the inlet end of the reverse flow channel 4 is connected to the middle of the central flow channel 2, but the outlet end of the reverse flow channel 4 extends to the gauge-maintaining section slope of the blade 102. It is mainly suitable for medium-sized drill bit bodies 1, especially 8 3 / 8” to 13 5 / 8” drill bit bodies 1. The inner wall thickness of the chip removal groove 103 of the medium-sized drill bit body 1 is limited, and it is not advisable to make additional holes. The shank 101 is far from the bottom of the well. Therefore, extending the outlet end of the reverse flow channel 4 to the gauge-maintaining section slope of the blade 102, which is located in the middle and has sufficient thickness, not only ensures the formation of negative pressure, but also reduces the manufacturing difficulty.

[0034] Furthermore, Figure 5 This application provides a schematic diagram of a third embodiment of the reverse flow channel 4 in a pulse negative pressure suction PDC drill bit, as shown in the following example. Figure 5As shown, in the third embodiment, the inlet end of the reverse flow channel 4 is connected to the middle of the central flow channel 2, but the outlet end of the reverse flow channel 4 extends to the shank 101 of the drill bit body 1. It is mainly suitable for small-sized drill bit bodies 1, especially 5 1 / 2”~7 1 / 2”. The axial length of the small-sized drill bit body 1 is relatively short, and setting it on the shank 101 will not cause the problem of being too far from the bottom of the well to form negative pressure.

[0035] Furthermore, in the above three embodiments, the outlet end of the reverse flow channel 4 is provided with a pulse nozzle 6, the flow channel diameter is 5mm to 25mm, and the spray angle β of the pulse nozzle 6 is 0°≤β≤30° with the central axis of the drill bit shank 101. The pulse nozzle 6 can generate periodic and intermittent high-speed jets, which can generate strong impact and disturbance on the rock cuttings layer deposited in the annulus, destroy its stability, and make it easier for it to be carried away by the mainstream rock-carrying fluid flow. At the same time, the pulsed discharge will form periodic pressure fluctuations in the annulus, making it easier to generate a negative pressure suction effect, limiting the β angle to within 30°, and ensuring that the pulse energy is mainly used to generate axial impact and disturbance, rather than wasted on radial scouring of the well wall.

[0036] In addition, the installation positions of the pulse nozzle 6 and the surface nozzle 5 in this application can be flexibly interchanged, that is, the surface nozzle 5 is installed on the reverse flow channel 4 and the pulse nozzle 6 is installed on the forward flow channel 3.

[0037] Furthermore, Figure 6 This application provides a schematic diagram of the pulse nozzle 6 structure in a pulse negative pressure suction PDC drill bit, as shown in the embodiment of the present application. Figure 6 As shown, in one possible embodiment, the pulse nozzle 6 includes a second water inlet 601, a self-excited oscillation chamber 602, a second loading and unloading part 603, a second water outlet 604, and a second connecting thread 605. It is characterized by using a hard alloy with high hardness and high wear resistance as the base material. Without the need for any auxiliary devices, it generates oscillation, amplification, and feedback by relying on its own self-excited oscillation chamber 602, so that the jet generates oscillating pulses and transforms the continuous jet into pulse jet.

[0038] Furthermore, this application can adapt to different rock formation characteristics and drilling needs by adjusting the flow rate ratio of drilling fluid in the forward flow channel 3 and the reverse flow channel 4, ensuring efficient and coordinated "rock breaking-cooling-cutting removal" functions. The flow rate distribution ratio is as follows: For dense hard rock formations: the ratio of forward flow rate Q1 to reverse flow rate Q2 is 7:3 to 8:2. During hard rock drilling, the PDC teeth experience high cutting load and generate a lot of heat, requiring more forward flow rate to cool the tooth surface and prevent overheating and wear of the tooth tips; the reverse flow rate is only needed for basic suction to avoid rock cuttings accumulation.

[0039] For medium-soft rock formations: the ratio of forward flow rate Q1 to reverse flow rate Q2 is 6:4 to 7:3. Medium-soft rocks are prone to generating a large amount of rock cuttings. Simply pushing forward can easily form a rock cuttings bed. It is necessary to increase the reverse flow rate to enhance suction, while retaining more forward flow rate, taking into account both tooth cooling and rock cuttings pushing, and balancing the two core requirements. For fractured formations prone to leakage: the ratio of forward flow rate Q1 to reverse flow rate Q2 is 5:5 to 6:4. Pressure imbalance in fractured formations can easily lead to drilling fluid loss. Reverse flow rate can enhance the negative pressure effect, balance the pressure in the well, and reduce the risk of leakage. Forward flow rate ensures base cooling and prevents overheating of the drilling fluid due to insufficient flow.

[0040] Furthermore, this application systematically optimizes the parameters of the pulse nozzle 6 to solve problems such as insufficient jet pulse intensity and low suction efficiency in traditional nozzles, thereby achieving a synergistic improvement in the "rock breaking-cooling-chip removal" function of the drill bit in different formations. The preferred pulse frequency is as follows: Dense hard rock formations: pulse jet frequency 18-20Hz. Hard rock has a large cutting load and high heat generation. High-frequency pulse jet can enhance the jet impact and suction, quickly remove rock cuttings, and at the same time assist in cooling the cutting teeth 104.

[0041] Medium-soft rock formations: pulse jet frequency 12-15Hz. Medium-soft rocks are prone to producing a large amount of rock debris. Medium-frequency pulse jets can balance suction efficiency and energy consumption, and avoid rock debris splashing caused by high frequencies.

[0042] For fractured formations prone to leakage: pulse jet frequency 10-12Hz. For formations prone to leakage, bottomhole pressure control is necessary. Low-frequency pulse jets can reduce jet impact pressure and simultaneously balance the negative pressure inside the well through stable pumping, preventing leakage.

[0043] In the description of this application, it should be noted that the terms "upper," "lower," etc., indicating the orientation or positional relationship are based on the orientation or positional relationship shown in the accompanying drawings, and are only for the convenience of describing this application 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, and therefore should not be construed as a limitation of this application. Unless otherwise expressly specified and limited, the terms "installed," "connected," and "linked" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication between two elements. For those skilled in the art, the specific meaning of the above terms in this application can be understood according to the specific circumstances.

[0044] It should be noted that in this application, relational terms such as "first" and "second" are used merely to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitations, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes said element.

[0045] The above description is merely a specific embodiment of this application, enabling those skilled in the art to understand or implement this application. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of this application. Therefore, this application is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features claimed herein.

Claims

1. A pulse negative pressure suction PDC drill bit, characterized in that, include: The drill bit body (1) includes a working end for drilling and a docking end for connecting to an external power component; The flow channel assembly includes a central flow channel (2) axially disposed within the drill bit body (1), a plurality of forward flow channels (3) circumferentially arranged and connected to the bottom of the central flow channel (2), and a plurality of reverse flow channels (4) circumferentially arranged and connected to the middle of the central flow channel (2). The outlet end of the forward flow channel (3) is located at the working end of the drill bit body (1) to form a first pressure between the working end of the drill bit body (1) and the bottom wall of the borehole. The outlet end of the reverse flow channel (4) is located at the middle of the drill bit body (1), and the number of reverse flow channels (4) is less than the number of forward flow channels (3) to form a second pressure less than the first pressure in the annulus of the drill bit body (1).

2. The pulse negative pressure suction PDC drill bit as described in claim 1, characterized in that: The drill bit body (1) includes a shank (101), one end of which is provided with a plurality of blades (102) to form a working end, and the other end of which is provided with an external thread to form a mating end.

3. The pulse negative pressure suction PDC drill bit as described in claim 2, characterized in that: Adjacent blades (102) form chip removal grooves (103).

4. The pulse negative pressure suction PDC drill bit as described in claim 3, characterized in that: One end of the blade (102) is located at the center of the handle (101), and the other end spreads radially along the handle (101). The blade (102) forms an inner cone section, a nose shoulder section and a diameter-maintaining section in sequence in a direction that gradually moves away from the center of the handle (101), and cutting teeth (104) are provided on the inner cone section, the nose shoulder section and the diameter-maintaining section.

5. The pulse negative pressure suction PDC drill bit as described in claim 2, characterized in that: The central flow channel (2) is axially located at the center of the handle (101), and one end of the central flow channel (2) passes through the docking end, while the other end is connected to the forward flow channel (3).

6. The pulse negative pressure suction PDC drill bit as described in claim 3, characterized in that: The inlet ends of multiple forward flow channels (3) converge at the center of the handle (101) to connect with the central flow channel (2). The outlet ends of the forward flow channels (3) diffuse radially along the handle (101). The outlet ends of the forward flow channels (3) are located in the chip removal groove (103), and the outlet ends of the forward flow channels (3) are provided with surface nozzles (5).

7. The pulse negative pressure suction PDC drill bit as described in claim 4, characterized in that: The inlet end of the reverse flow channel (4) is connected to the middle of the central flow channel (2), the outlet end of the reverse flow channel (4) is located at the chip removal groove (103), and the outlet end of the reverse flow channel (4) is higher than the outlet end of the forward flow channel (3).

8. The pulse negative pressure suction PDC drill bit as described in claim 4, characterized in that: The outlet end of the reverse flow channel (4) is located in the diameter protection section of the blade (102).

9. The pulse negative pressure suction PDC drill bit as described in claim 4, characterized in that: The outlet end of the reverse flow channel (4) is located in the middle of the handle (101).

10. The pulse negative pressure suction PDC drill bit as described in claim 1, characterized in that: The outflow end of the reverse flow channel (4) is provided with a pulse nozzle (6).

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