A double helix angle PDC bit

Abstract

This invention proposes a double-helix angle PDC drill bit, comprising: a connecting end and a drill body; a plurality of blades on the outer wall of the drill body; cutting teeth on the outer surface of the blades; the blades include n+1 first blades and n second blades; both the first and second blades include a nose, a shoulder, an outer diameter arc section, and a gauge-protecting section; the second blades also include an inner cone section, which connects to the nose and faces the center of the free end face of the drill body; the first and second blades employ helical structures with different helix angles. The double-helix angle PDC drill bit of this invention, with an odd number of blades at the drill body end, forms an asymmetrical arrangement; and the different helix angles of the first and second blades reduce the radial force on the gauge-protecting end face, lowering vibration during drill operation, thereby improving drill stability and extending drill life.

Description

Technical Field

[0001] This invention belongs to the field of oil and gas exploration technology, and specifically relates to a double helix angle PDC drill bit. Background Technology

[0002] Polycrystalline diamond compact (PDC) drill bits are a new type of high-efficiency rock-breaking tool in the field of drilling engineering technology. PDC drill bits improve their overall working performance through reasonable structural design and scientific tooth arrangement. The drill bit structure design, such as drill bit size, cutter wing shape, type of cutting teeth and arrangement pattern, directly affects key performance indicators such as drill bit mechanical drilling speed, wear rate and drilling stability. With the continuous deepening of research on PDC cutting tooth materials and tooth shape, and with the advancement of drilling depth to deep and ultra-deep formations, when drilling large-size wells in complex formations, conventional PDC drill bits are often used as a basis to directly increase the drill bit size. This leads to slow drill bit footage, low rock-breaking efficiency, short drill bit life and easy tooth breakage when drilling large-size wells in complex formations.

[0003] Chinese patent CN110374513A discloses a PDC drill bit suitable for complex lithological formations. The inner cone surface of the PDC drill bit adopts a shallow cone structure, and the inner cone angle of the PDC drill bit is limited to less than 10 degrees. The arc of the cone part of the PDC drill bit is greater than 10 rad. The PDC drill bit adopts short diameter protection and sets a certain helix angle, which improves the drill bit's attack capability and avoids the adverse phenomenon of the cutting teeth being damaged prematurely due to excessive impact.

[0004] However, the PDC drill bit in the above-mentioned prior art has a simple drill bit profile and blade structure. It only improves the working efficiency of the drill bit by increasing the specification of a single blade. For large-sized drill bits, the rock breaking utilization rate of the cutting teeth is low. Summary of the Invention

[0005] To address the aforementioned problems, this invention proposes a double helix angle PDC drill bit, comprising: a connecting end and a drill body coaxially connected, wherein a plurality of blades are provided circumferentially on the outer wall of the free end of the drill body, and a plurality of cutting teeth are provided on the outer surface of the blades in a linear array, wherein the blades include n+1 first blades and n second blades.

[0006] Both the first and second cutter wings include a nose, a shoulder, an outer diameter arc section, and a diameter-protecting section. The nose, shoulder, and outer diameter arc section are located on the free end face of the drill body and are arranged sequentially from the center of the free end face of the drill body outward. The diameter-protecting section is located on the side wall of the drill body and is connected to the outer diameter arc section.

[0007] The second blade also includes an inner cone, which connects with the nose and faces the center of the free end face of the drill body, and one of the free ends of the inner cone coincides with the center of the free end face of the drill body.

[0008] The first and second blades each employ a helical structure with different helical angles.

[0009] Furthermore, the blade wings, including the second blade wing and the first blade wing, are arranged in a staggered manner.

[0010] Furthermore, the outer surface of the inner cone of the second blade is designed with a conical surface, with a cone angle of 125° to 145°.

[0011] Furthermore, the center line of the nose maintains a first distance from the center of the free end face of the drill bit body, and the center line of the nose maintains a second distance from the outer ring sidewall of the diameter protection part, with the ratio of the first distance to the second distance being 0.600-0.618.

[0012] Furthermore, the outer surface contours of the nose, shoulder, and outer diameter arc of the blade wing together form a parabolic segment, with the highest point being at the connection between the nose and shoulder.

[0013] Furthermore, the thickness of the blade's body is 5-10 mm.

[0014] Furthermore, the cutting teeth include: axe-shaped cutting teeth, wear-resistant Mercedes-Benz teeth, bevel teeth, flat teeth, and diameter-maintaining teeth;

[0015] The outer surface of the inner conical part of the second blade is fitted with flat teeth, the outer surface of the nose, shoulder, and outer diameter arc part is fitted with wear-resistant Mercedes teeth and conical teeth, and the outer surface of the diameter-protecting part is fitted with diameter-protecting teeth.

[0016] The nose, shoulder, and outer diameter arc surface of the first blade are equipped with axe-shaped cutting teeth and conical teeth, while the outer surface of the diameter-protecting part is equipped with diameter-protecting teeth.

[0017] Furthermore, the cutting teeth are arranged in a double-row, displaced configuration.

[0018] Furthermore, the back rake angle of the cutting teeth is greater than 0° and less than 30°, and the side rake angle is greater than or equal to 5° and less than 20°.

[0019] Furthermore, a well fluid flow channel is provided between the connecting end and the drill bit body cavity, and several water eye channels are provided inside the drill bit body to connect the well fluid flow channel with the free end face of the drill bit body.

[0020] Compared with the prior art, the embodiments of the present invention have at least the following advantages:

[0021] The double-helix angle PDC drill bit of the present invention has an odd number of blades arranged in a circumferential array at the end of the drill bit body, thus forming an asymmetrical arrangement. Furthermore, the different helix angles of the first and second blades reduce the radial force on the end face of the gauge section, lowering vibration during drill bit operation and improving drill bit stability and service life. The second blade extends from the outermost ring to the center of the drill bit body end face, achieving full coverage and ensuring a complete working area. The inner cone portion prevents the problem of reduced mechanical drilling speed due to failure to break rock in time at the center of the drill bit end face. The corresponding first blade assists the second blade in preferentially engaging and breaking the rock, reducing wear on the blade teeth and improving the drill bit's rock-breaking efficiency.

[0022] Other features and advantages of the invention will be set forth in the following description, and will be apparent in part from the description, or may be learned by practicing the invention. The objects and other advantages of the invention may be realized and obtained by means of the structures pointed out in the description and the drawings. Attached Figure Description

[0023] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0024] Figure 1 A schematic diagram of a double-helix angle PDC drill bit in an embodiment of the present invention is shown;

[0025] Figure 2 A cross-sectional schematic diagram of a double-helix angle PDC drill bit in an embodiment of the present invention is shown;

[0026] Figure 3 A top view schematic diagram of a double helix angle PDC drill bit in an embodiment of the present invention is shown;

[0027] Figure 4 A schematic diagram of the structural composition of the second blade in an embodiment of the present invention is shown;

[0028] Figure 5 A schematic diagram of the blade distribution in an embodiment of the present invention is shown;

[0029] Figure 6 A schematic diagram of the inclination angle of the cutting teeth in an embodiment of the present invention is shown;

[0030] Figure 7 A schematic diagram of the axe-shaped cutting teeth in an embodiment of the present invention is shown;

[0031] Figure 8 A schematic diagram of the wear-resistant Mercedes tooth structure in an embodiment of the present invention is shown.

[0032] In the figure, the connecting end is 1, the drill bit body is 2, the cutter wing is 3, the first cutter wing is 301, the second cutter wing is 302, the cutting tooth is 4, the axe-shaped cutting tooth is 401, the wear-resistant Mercedes tooth is 402, the conical tooth is 403, the flat tooth is 404, the diameter-maintaining tooth is 405, the well fluid flow channel is 5, the water eye channel is 6, the inner cone is 7, the nose is 8, the shoulder is 9, the outer diameter arc section is 10, the diameter-maintaining section is 11, the inner diameter annular zone is 12, the middle diameter annular zone is 13, and the outer diameter annular zone is 14. Detailed Implementation

[0033] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0034] This invention provides a double helix angle PDC drill bit. Figure 1 A schematic diagram of a double-helix angle PDC drill bit according to an embodiment of the present invention is shown. Figure 1 In the middle, the double helix angle PDC drill bit includes: a connecting end 1 and a drill body 2 connected coaxially. The outer wall of the free end of the drill body 2 is provided with several blades 3 in the circumferential direction, and several cutting teeth 4 arranged in a linear array are provided on the outer surface of the blades 3.

[0035] The blade 3 includes n+1 first blades 301 and n second blades 302;

[0036] Both the first cutter wing 301 and the second cutter wing 302 include a nose 8, a shoulder 9, an outer diameter arc-shaped part 10, and a diameter-protecting part 11. The nose 8, shoulder 9, and outer diameter arc-shaped part 10 are located on the free end face of the drill body 2 and are arranged sequentially from the center of the free end face of the drill body 2 outward. The diameter-protecting part 11 is located on the side wall of the drill body 2 and is connected to the outer diameter arc-shaped part 10.

[0037] The second blade 302 also includes an inner cone 7, which is connected to the nose 8 and faces the center of the free end face of the drill body 2, and one of the free ends of the inner cone 7 coincides with the center of the free end face of the drill body 2.

[0038] In this application, the PDC drill bit has a helical structure for both the first cutter 301 and the second cutter 302, but the helical angles of the first cutter 301 and the second cutter 302 are different.

[0039] For example, refer to Figure 5Taking the drill bit body 2 with a maximum outer diameter of 444.5mm as an example, based on the design principle and theory of helix angle suitable for hard formations and smaller helix angle suitable for soft formations, the helix angle of the first cutter wing 301 is designed to be α1 = 20° and the helix angle of the second cutter wing 302 is α2 = 30° for complex and difficult-to-drill formations. The distance from the tail end of the first cutter wing 301 to the center of the drill bit is 88.6mm. The distance between the end face of the second cutter wing 302 and the first cutter wing 301 and the free end of the drill bit is 26mm. The end face length of the diameter-protecting part 11 of the cutter wing 3 is 78mm. Based on the two helix angles, the applicable formations of the drill bit are improved, while the requirements for drilling pressure and torque are reduced, the cutting efficiency of the drill bit is improved, and the needs of large-size drilling operations are met.

[0040] An odd number of blades 3 are arranged in a circumferential array at the end of the drill bit body 2, forming an asymmetrical arrangement. The different helical angles of the first blade 301 and the second blade 302 reduce the radial force on the end face of the gauge section 11, thereby reducing vibration during drill bit operation, improving drill bit stability, and extending drill bit service life. The second blade 302 extends from the outermost ring to the center of the end face of the drill bit body 2, achieving full coverage of the end face of the drill bit body 2, ensuring a complete working area. The inner cone section 7 prevents the problem of the drill bit end face center position failing to break the rock in time, thus reducing the mechanical drilling speed. The corresponding first blade 301 assists the second blade 302 in prioritizing and cooperating in biting and breaking the rock, reducing the wear of the teeth on the blade 3 and improving the rock breaking efficiency of the drill bit.

[0041] Specifically, in Figure 1 In the example shown, there are 7 blades 3, which include 3 second blades 302 and 4 first blades 301. The 3 second blades 302 and 4 first blades 301 are arranged in a staggered manner.

[0042] refer to Figure 5 The specific layout of the three second cutter wings 302 and the four first cutter wings 301 is described in detail. With the rotation angle of one of the second cutter wings 302 selected as 0°, the three second cutter wings 302 are distributed at azimuths of 0°, 154°, and 257°, ​​respectively, while the four first cutter wings 301 are distributed at azimuths of 51°, 103°, 206°, and 308°, respectively. Through the asymmetrical and staggered arrangement of the seven cutter wings 3, the vibration frequency of the drill bit is reduced, thereby improving the stability of the drill bit.

[0043] For details, please refer to Figure 4The outer surface of the inner cone 7 of the second blade 302 adopts a conical design with a cone angle of 125° to 145°. For example, the cone angle is 135°, which limits the magnitude of the drill bit contact pressure and the rock contact, thereby achieving a smaller cutting depth and reducing the single-point cutting load. This enables effective rock breaking without excessive wear or unnecessary stress concentration, enhances the drill bit's guidance and attack capability, and effectively reduces wear, extending the drill bit's service life.

[0044] refer to Figure 4 To further explain, the first distance between the center line of the nose 8 and the center of the free end face of the drill bit body 2 is set as L1, and the second distance between the center line of the nose 8 and the outer ring sidewall of the diameter protection part 11 is set as L2. The ratio of L1 to L2 is 0.600-0.618.

[0045] During drilling operations, the nose section 8 is the first area of ​​the drill bit to contact the rock. By adopting the golden ratio design, the nose section 8 is located on the radial golden ratio line of the drill bit, which increases the overall stability of the drill bit during rock breaking. For example, the distance between the center line of the nose section and the center of the drill bit L1 is 84.89 mm, and the distance between the nose section and the gauge end face L2 is 137.36 mm.

[0046] Correspondingly, the outer surface contours of the nose 8, shoulder 9, and outer diameter arc surface 10 of the blade 3 together form a parabolic segment, and the connection between the nose 8 and the shoulder 9 is the highest point, so that the overall crown surface of the blade 3 adopts a medium-parabolic design. It should be noted that the crown surface type of drill bit in this field is divided into flat parabolic surface, short parabolic surface, medium parabolic surface, and long parabolic surface. Among them, the medium parabolic surface is suitable for medium-hard to hard formations with strong abrasiveness, which further improves the adaptability of the drill bit to various formations and meets the attack capability of the drill bit of this application.

[0047] Meanwhile, the outer surface of the nose 8 adopts a large curved surface structure to increase the working area of ​​the outer surface of the nose 8, thereby improving the drill bit's impact resistance.

[0048] Furthermore, the blade 3 in this application adopts a more compact ultra-thin matrix structure, thereby reducing the thickness of the blade 3. The matrix thickness of the blade 3 is 5-10mm. The ultra-thin matrix design reduces the total mass of the drill bit and the amount of material used while ensuring sufficient structural strength. The material used is nickel-based alloy, copper-based alloy or cemented carbide (tungsten-based powder). The ultra-thin matrix combined with high wear-resistant cutting teeth can significantly improve the mechanical drilling rate (ROP) and drill bit life, and increase the depth and volume of the corresponding chip removal channel, directly improving the hydraulic cleaning effect.

[0049] exist Figure 3 In the example shown, the cutting tooth 4 includes: axe-shaped cutting tooth 401, wear-resistant Benz tooth 402, bevel tooth 403, flat tooth 404, and diameter-maintaining tooth 405;

[0050] For ease of explanation, the free end face of the drill bit body 2 is divided into the following sections according to its distance from the center: inner diameter annular zone 12, middle diameter annular zone 13, and outer diameter annular zone 14.

[0051] Among them, the inner diameter ring section 12 of the second cutter wing 302 is an inner cone 7, and the inner diameter ring section 12 is equipped with a flat tooth 404. The middle diameter ring section 13 and the outer diameter ring section 14 correspond to the nose 8, shoulder 9, and outer diameter arc section 10, respectively. The outer surfaces of the middle diameter ring section 13 and the outer diameter ring section 14 are equipped with wear-resistant Mercedes teeth 402 and conical teeth 403. According to the rotation direction of the drill bit, the wear-resistant Mercedes teeth 402 are located upstream of the conical teeth 403.

[0052] The middle diameter ring section 13 and the outer diameter ring section 14 of the first cutter wing 301 are equipped with axe-shaped cutting teeth 401 and conical teeth 403. According to the rotation direction of the drill bit, the axe-shaped cutting teeth 401 are located upstream of the conical teeth 403.

[0053] Meanwhile, diameter-protecting teeth 405 are installed on the outer surface of the diameter-protecting part 11 of all blades 3.

[0054] For example, the axe-shaped cutting tooth 401, the wear-resistant Benz tooth 402, and the flat tooth 404 have an outer diameter of 16mm, a total length of 18mm, a PDC sheet thickness of 3mm, and a conical tooth 403 with an outer diameter of 16mm and a tooth tip angle of 100°.

[0055] Meanwhile, for ease of explanation, please refer to Figure 7 and Figure 8 , Figure 7 A schematic diagram of the axe-shaped cutting teeth in an embodiment of the present invention is shown. Figure 8 A schematic diagram of the wear-resistant Mercedes tooth structure in an embodiment of the present invention is shown;

[0056] Based on the excellent rock-breaking performance of the special-shaped teeth, a variety of special-shaped teeth with different functions are combined and assembled: specifically, the nose 8 and shoulder 9 of the second cutter wing 302 adopt wear-resistant Mercedes teeth 402, and the nose 8 and shoulder 9 of the first cutter wing 301 adopt axe-shaped cutting teeth 401. By alternating operations, the impact resistance and wear resistance of the drill bit are improved.

[0057] Meanwhile, in order to further improve the overall stability of the drill bit, the cutting teeth 4 adopt a double-row, displaced, and closely spaced layout to increase the tooth density. The spacing between the cutting teeth 4 in the same row is 2mm, and the spacing between the cutting teeth 4 in the front and rear rows is 4mm. For example, the axe-shaped cutting teeth 401 have 28 teeth, the wear-resistant Mercedes teeth 402 have 21 teeth, the conical teeth 403 have 21 teeth, the flat teeth 404 have 13 teeth, and the diameter-maintaining teeth 405 have 56 teeth.

[0058] This ensures that the working surface of cutting tooth 4 covers the entire bottom of the well, thereby enhancing the rock-breaking efficiency of the drill bit and reducing tooth wear.

[0059] Correspondingly, during the operation, the nose 8 and shoulder 9 of the middle annular section take in and break up the whole rock block, and the inner cone 7 of the inner diameter annular section 12 breaks up the rock and fragments that have moved to the center of the drill bit, so as to further crush the rock block until it is completely crushed. At the same time, the diameter protection section 11 and the outer diameter arc section 10 of the outer diameter annular section 14 are used to break up and enlarge the wellbore.

[0060] To further improve the drilling efficiency, and considering the different functions of different parts of the cutter blade 3, in Figure 6 In the example shown, the cutting tooth 4 has different back tilt angles and side rotation angles on the blade 3. The back tilt angle a can be selected as 0° < a < 30°, and the side rotation angle b can be selected as 5° ≤ b < 20°.

[0061] For example: the back tilt angle a of the cutting tooth 4 in the inner diameter ring zone 12 is designed to be 15°, and the side rotation angle b is designed to be 10°;

[0062] The back tilt angle a of the cutting tooth 4 in the middle ring section is designed to be 20°, and the side rotation angle b is designed to be 20°.

[0063] The back tilt angle a of the cutting tooth 4 in the outer diameter ring section 14 is designed to be 30°, and the side rotation angle b is designed to be 15°.

[0064] This improves the efficiency of the drill bit, makes reasonable use of the functional characteristics of various cutting teeth, and reduces tooth wear;

[0065] In addition, a well fluid flow channel 5 is provided inside the connecting end 1 and the drill bit body 2, and several water eye channels 6 are provided inside the drill bit body 2, connecting the well fluid flow channel 5 and the free end face of the drill bit body 2. Figure 1 In the example shown, the drill bit has 11 water channels, with 4 located in the inner diameter annular zone 12 and the remaining 7 located on the boundary between the inner diameter annular zone 12 and the middle diameter annular zone 13. The water channel 6 is arranged in a circumferential array about the center of the free end of the drill bit body 2, so that there is at least one water channel 6 between adjacent blades 3. For example, the size of the water channel 6 is 30mm, which increases the cleaning area for washing and carrying away rock cuttings from the drill bit, and reduces the secondary wear on the teeth caused by rock cuttings retention.

[0066] In the description of this invention, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "linking" 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, an electrical connection, or a connection that allows for communication; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal connection of multiple components or the interaction between multiple components. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0067] Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A dual helix angle PDC bit comprising: The connecting end (1) and the drill body (2) are coaxially connected, characterized in that the outer wall of the free end of the drill body (2) is provided with a plurality of blades (3) in the circumferential direction, and the outer surface of the blades (3) is provided with a plurality of cutting teeth (4) arranged in a linear array, wherein the blades (3) include n+1 first blades (301) and n second blades (302); The first cutter wing (301) and the second cutter wing (302) both include a nose (8), a shoulder (9), an outer diameter arc surface (10), and a diameter protection part (11). The nose (8), shoulder (9), and outer diameter arc surface (10) are located on the free end face of the drill bit body (2) and are arranged in sequence from the center of the free end face of the drill bit body (2) outward. The diameter protection part (11) is located on the side wall of the drill bit body (2) and is connected to the outer diameter arc surface (10). The second blade (302) also includes an inner cone (7), which is connected to the nose (8) and faces the center of the free end face of the drill body (2), and the free end of one of the inner cones (7) coincides with the center of the free end face of the drill body (2); The first blade (301) and the second blade (302) adopt helical structures with different helical angles.

2. The dual helix angle PDC bit of claim 1, wherein, The blade (3) includes a second blade (302) and a first blade (301) arranged in a staggered manner.

3. The dual helix angle PDC bit of claim 2, wherein, The outer surface of the inner cone portion (7) of the second blade (302) is designed with a conical surface, and the included angle of the conical surface is 125° to 145°.

4. The double helix angle PDC drill bit according to claim 3, characterized in that, The center line of the nose (8) maintains a first distance from the center of the free end face of the drill bit body (2), and the center line of the nose (8) maintains a second distance from the outer ring sidewall of the diameter protection part (11). The ratio of the first distance to the second distance is 0.600-0.

618.

5. The double helix angle PDC drill bit according to claim 4, characterized in that, The outer surface contours of the nose (8), shoulder (9) and outer diameter arc (10) of the blade (3) together form a parabolic segment, and the connection between the nose (8) and shoulder (9) is the highest point.

6. The double helix angle PDC drill bit according to claim 5, characterized in that, The thickness of the blade (3) is 5-10 mm.

7. The double helix angle PDC drill bit according to claim 2, characterized in that, The cutting teeth (4) include: axe-shaped cutting teeth (401), wear-resistant Mercedes teeth (402), conical teeth (403), flat teeth (404), and diameter-maintaining teeth (405); The outer surface of the inner cone portion (7) of the second blade (302) is fitted with flat teeth (404), the outer surface of the nose portion (8), shoulder portion (9), and outer diameter arc portion (10) is fitted with wear-resistant Mercedes teeth (402) and conical teeth (403), and the outer surface of the diameter-protecting portion (11) is fitted with diameter-protecting teeth (405). The nose (8), shoulder (9), and outer diameter arc section (10) of the first blade (301) are equipped with axe-shaped cutting teeth (401) and conical teeth (403), and the outer diameter protection section (11) is equipped with diameter protection teeth (405).

8. The double helix angle PDC drill bit according to claim 7, characterized in that, The cutting teeth (4) are arranged in a double-row, out-of-position configuration.

9. The double helix angle PDC drill bit according to claim 2, characterized in that, The back tilt angle of the cutting tooth (4) is greater than 0° and less than 30°, and the side rotation angle is greater than or equal to 5° and less than 20°.

10. The double helix angle PDC drill bit according to any one of claims 1 to 9, characterized in that, The connecting end (1) and the inner cavity of the drill bit body (2) are provided with well fluid flow channels (5), and the drill bit body (2) is provided with a number of water eye channels (6) that connect the well fluid flow channels (5) with the free end face of the drill bit body (2).

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