Peak valley cutting PDC (Polycrystalline Diamond Compact) bit suitable for coring in hard plastic stratum

Abstract

The invention discloses a peak valley cutting PDC drill bit suitable for coring of hard plastic stratum.The peak valley cutting PDC drill bit comprises a crown body and a connector, the crown body is of a hollow structure, an inner flow channel is formed in the inner wall of the crown body, an outer flow channel is formed in the outer wall of the crown body, and a wear-resisting layer is arranged on the inner wall of the crown body; six blades are arranged on the outer wall of the crown body, the blades numbered according to odd numbers and the blades numbered according to even numbers are arranged in a staggered mode, the included angle formed by any two adjacent blades numbered according to odd numbers and blades numbered according to even numbers is 60 degrees, sharp round teeth, first back reaming teeth and first strengthening teeth are arranged on the blades numbered according to odd numbers, and the included angle formed by the blades numbered according to even numbers is 60 degrees. The even number of blades are provided with round teeth, second back reaming teeth and second strengthening teeth, and the end of the crown body is provided with fan-shaped water holes inclining from inside to outside. In the coring operation of the hard plastic stratum, the rock core breakage rate can be reduced, and the rock core yield and the rock core obtaining quality are effectively improved.

Description

Technical Field

[0001] The invention relates to the technical field of geological exploration equipment, in particular to a peak-to-valley cutting PDC drill bit suitable for coring hard plastic strata. Background Art

[0002] In the exploration of energy resources such as oil and natural gas, as well as in geological research, coring drilling is an important means of obtaining subsurface information. However, the unique physical properties of hard-plastic formations pose numerous challenges to coring operations.

[0003] Hard-plastic formations are primarily composed of rocks such as mudstone, which exhibit high hardness and significant plastic deformation properties. During drilling, when weight on bit is applied, the formation undergoes elastic deformation, making it difficult for conventional PDC drill bits to effectively penetrate the formation. This leads to frequent drill bit slippage, resulting in extremely low drilling efficiency and even zero footage. Furthermore, hard-plastic formations can easily increase wear on the drill bit's cutting teeth, significantly shortening the bit's service life and increasing drilling costs. Furthermore, during coring operations, existing technologies often produce cores with poor integrity, making them difficult to meet the requirements of subsequent work such as geological analysis.

[0004] Currently, traditional PDC drill bits perform well in drilling soft to medium-hard formations, but they exhibit numerous limitations in hard-plastic formations. For example, the shape and placement of their cutting teeth are unable to effectively cut and crush in hard-plastic formations. Conventional hydraulic structures also fail to meet the demands of core drilling in hard-plastic formations. For example, insufficient cuttings-carrying capacity can easily lead to cuttings accumulation at the bottom of the well, which not only affects drilling efficiency but also has a negative impact on core quality. Although the performance of PDC drill bits has improved with the development of diamond technology, such as improvements to the diamond layer of diamond composite sheets that enhance the abrasion resistance and impact resistance of the cutting teeth, and non-planar interface technology that strengthens the bond strength between the diamond layer and the hard substrate, these improvements are still insufficient to effectively solve the problem of core drilling in hard-plastic formations.

[0005] As oil and gas exploration and development gradually advances to complex formations such as deep layers and deep seas, and as the requirements for core drilling quality in hard-plastic formations in fields such as geological exploration continue to increase, there is an urgent need to develop an efficient PDC drill bit suitable for core drilling in hard-plastic formations to improve drilling efficiency, reduce costs, and meet high requirements for core quality.

[0006] A Chinese patent document with publication number CN119900469A and publication date April 29, 2025, discloses a fractured blade PDC drill bit, characterized in that it includes a base, a first blade group, a second blade group, and a hydraulic structure, wherein: The substrate includes a liquid flow channel, and the liquid flow channel is used to provide a flow channel for drilling fluid; The first blade group includes at least two first blades, the first blades extending outward from the center of the end of the base, and the area enclosed by two adjacent first blades and the base forms a chip removal area; The second blade group includes at least two second blades, the second blades extending outward from the outer edge of the end of the base, and the height of the second blades is greater than the height of the first blades, and the at least two second blades and the at least two first blades are staggered relative to each other along the circumference of the base; The hydraulic structure is arranged in at least one of the chip removal areas, and the hydraulic structure at least includes a water eye, and the water eye is connected to the liquid flow channel.

[0007] The patent document discloses a fractured blade PDC drill bit that combines a first and second blade assembly. The second blade is taller than the first blade, and the two blades are staggered. This, combined with the water holes and nozzles in the hydraulic structure, effectively clears rock cuttings and protects the cutting elements, improving rock breaking efficiency and preventing rock cutting blockage and excessive wear of the cutting elements. However, in coring operations in hard-plastic formations, the core recovery rate and quality are poor. Summary of the Invention

[0008] To overcome the above-mentioned shortcomings of the prior art, the present invention provides a peak-to-valley cutting PDC drill bit suitable for coring in hard-plastic formations. The present invention can reduce the core breakage rate during coring operations in hard-plastic formations, effectively improving the core recovery rate and the quality of core acquisition. The present invention is achieved through the following technical solutions: The peak-valley cutting PDC drill bit suitable for coring hard plastic formations includes a crown body and a joint, which is connected to the crown body and is characterized in that: the crown body is a hollow structure, an inner flow channel is opened on the inner wall of the crown body, and an outer flow channel is opened on the outer wall of the crown body, a wear-resistant layer is provided on the inner wall of the crown body, six blades numbered odd and even are provided on the outer wall of the crown body, the odd-numbered blades and the even-numbered blades are arranged alternately, and the angle formed by any two adjacent odd-numbered blades and the even-numbered blades is 60°, the odd-numbered blades are provided with sharp round teeth, a first inverted eye tooth and a first reinforced tooth, the even-numbered blades are provided with round teeth, a second inverted eye tooth and a second reinforced tooth, and a fan-shaped water eye hole inclined from the inside to the outside is provided on the end of the crown body.

[0009] The envelope formed by the sharp round teeth and the round teeth on the blade is a continuous wavy line with alternating peaks and valleys, and the height difference between the peaks and valleys is at least 1.5 mm.

[0010] The pointed round teeth are located at the crests of the envelope, and the round teeth are located at the troughs of the envelope.

[0011] The pointed round teeth include a fan-shaped top, a first fan-shaped inclined surface, a tooth portion and a second fan-shaped inclined surface, and the fan-shaped top, the first fan-shaped inclined surface, the tooth portion and the second fan-shaped inclined surface are integrally formed.

[0012] The width of the fan-shaped top is 1.5-4.0 mm.

[0013] The included angle between the oblique projections of the first sector-shaped inclined surface and the second sector-shaped inclined surface on the tooth surface of the tooth portion is 75-85°.

[0014] The included angle between the first sector-shaped inclined surface and the tooth surface of the tooth portion is 20-35°.

[0015] The angle between the axis of the fan-shaped water hole and the axis of the drill bit is 5-20 degrees.

[0016] The deflection angle between the fan-shaped water eye hole and the blade is -2-2°.

[0017] The blade comprises a cutting section and a gauge section, and the cutting section and the gauge section are integrally formed.

[0018] The pointed round teeth and round teeth are arranged on the cutting section.

[0019] The first inverted scoring teeth, the first strengthening teeth, the second inverted scoring teeth and the second strengthening teeth are all arranged on the gauge maintaining section.

[0020] The beneficial effects of the present invention are mainly manifested in the following aspects: 1. The present invention has a crown body with a hollow structure, an inner flow channel is provided on the inner wall of the crown body, an outer flow channel is provided on the outer wall of the crown body, a wear-resistant layer is provided on the inner wall of the crown body, and six blades numbered odd and even are provided on the outer wall of the crown body. The odd-numbered blades and the even-numbered blades are arranged alternately, and the angle formed by any two adjacent odd-numbered blades and even-numbered blades is 60°. The odd-numbered blades are provided with sharp round teeth, first inverted eye teeth and first reinforced teeth, and the even-numbered blades are provided with round teeth, second inverted eye teeth and second reinforced teeth. A fan-shaped water hole inclined from the inside to the outside is provided on the end of the crown body. Compared with the existing technology, in the coring operation of hard plastic formations, the core crushing rate can be reduced, and the core recovery rate and the core acquisition quality can be effectively improved. 2. In the present invention, the envelope formed by the sharp round teeth and round teeth on the blade is a continuous wavy line with alternating peaks and valleys, and the height difference between the peaks and valleys is at least 1.5 mm. The bottom hole morphology formed during the drilling process is a wavy shape with annular ridges. This can suppress the lateral vibration of the drill bit during drilling, improve the working stability of the coring tool during drilling, protect the core, and improve the core quality and recovery rate. 3. In the present invention, the pointed round teeth are located at the crest of the envelope line, and the round teeth are located at the trough of the envelope line. Under certain drilling pressure conditions, the pointed round teeth have strong drilling ability, can suppress the drill bit from slipping, and are easier to drill into the formation. The staggered arrangement of the round teeth and the pointed round teeth is easier to adapt to hard plastic formations, which can not only improve the cutting efficiency of hard plastic formations but also does not reduce the cutting efficiency of sandstone formations, and has good universality.

[0021] Fourth, the present invention adopts fan-shaped water holes inclined from the inside to the outside, which can effectively and fully cover and flush the mudstone adhering to the tooth surface, reduce repeated cutting, and achieve the effect of hydraulically assisted rock breaking.

[0022] 5. The present invention provides an inner flow channel on the inner wall of the crown body and an outer flow channel on the outer wall of the crown body to form a double flow channel, which can collaboratively discharge drill cuttings and improve drilling efficiency.

[0023] 6. The present invention provides a balanced cutting force by staggering the blades with odd numbers and the blades with even numbers, thereby avoiding stress concentration in the center area, thereby effectively protecting the core and improving the quality of core acquisition.

[0024] 7. The present invention, by specifically setting the crown body as a hollow structure and providing a fan-shaped water hole inclined from the inside to the outside on the end of the crown body, combined with the internal and external flow channels and the pointed round teeth, round teeth, first inverted eye teeth and second inverted eye teeth, can greatly improve the drilling ability and working stability of the drill bit in hard plastic formations, so as to solve the problems of drill bit slippage, slow footage, rapid wear of cutting teeth and poor coring quality when drilling in hard plastic formations of existing drill bits, and improve the coring quality and drilling efficiency in hard plastic formations. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] The present invention will be further described below in conjunction with the accompanying drawings and specific embodiments, wherein: Figure 1 It is a structural schematic diagram of the present invention; Figure 2 A top view of the present invention; Figure 3 This is a schematic structural diagram of the pointed round teeth of the present invention; Figure 4 for Figure 3 AA view in; Markings in the figure: 1, crown body, 2, joint, 3, inner flow channel, 4, outer flow channel, 5, blade, 6, pointed round tooth, 7, first inverted eye tooth, 8, first reinforced tooth, 9, round tooth, 10, second inverted eye tooth, 11, second reinforced tooth, 12, fan-shaped water hole, 13, fan-shaped top, 14, first fan-shaped inclined surface, 15, tooth part, 16, second fan-shaped inclined surface, 17, cutting section, 18, gauge section; , the angle between the first sector bevel and the second sector bevel projected on the tooth surface, w, the width of the sector top, , the angle between the first sector-shaped inclined surface and the tooth surface of the tooth portion. DETAILED DESCRIPTION

[0026] Example 1 See also Figure 1 , a peak-valley cutting PDC drill bit suitable for coring hard plastic formations, includes a crown body 1 and a joint 2, the joint 2 is connected to the crown body 1, the crown body 1 is a hollow structure, an inner flow channel 3 is opened on the inner wall of the crown body 1, and an outer flow channel 4 is opened on the outer wall of the crown body 1, a wear-resistant layer is provided on the inner wall of the crown body 1, and six blades 5 with odd and even numbers are provided on the outer wall of the crown body 1. The odd-numbered blade wings 5 ​​and the even-numbered blade wings 5 ​​are staggered, and the angle formed by any two adjacent odd-numbered blade wings 5 ​​and the even-numbered blade wings 5 ​​is 60°, and the odd-numbered blade wings 5 ​​are provided with sharp round teeth 6, first inverted eye teeth 7 and first strengthening teeth 8, and the even-numbered blade wings 5 ​​are provided with round teeth 9, second inverted eye teeth 10 and second strengthening teeth 11. The end of the crown body 1 is provided with a fan-shaped water eyelet 12 inclined from the inside to the outside.

[0027] This embodiment is the most basic implementation method. The crown body 1 is a hollow structure. An inner flow channel 3 is opened on the inner wall of the crown body 1, and an outer flow channel 4 is opened on the outer wall of the crown body 1. A wear-resistant layer is provided on the inner wall of the crown body 1, and six blade wings 5 ​​with odd and even numbers are provided on the outer wall of the crown body 1. The odd-numbered blade wings 5 ​​and the even-numbered blade wings 5 ​​are staggered. The angle formed by any two adjacent odd-numbered blade wings 5 ​​and the even-numbered blade wings 5 ​​is 60°. The odd-numbered blade wings 5 ​​are provided with sharp round teeth 6, first inverted eye teeth 7 and first reinforced teeth 8, and the even-numbered blade wings 5 ​​are provided with round teeth 9, second inverted eye teeth 10 and second reinforced teeth 11. A fan-shaped water hole 12 inclined from the inside to the outside is opened on the end of the crown body 1. Compared with the existing technology, in the coring operation of hard plastic formations, the core crushing rate can be reduced, and the core recovery rate and the core acquisition quality can be effectively improved. Example 2 See also Figure 1 and Figure 2, a peak-valley cutting PDC drill bit suitable for coring hard plastic formations, includes a crown body 1 and a joint 2, the joint 2 is connected to the crown body 1, the crown body 1 is a hollow structure, an inner flow channel 3 is opened on the inner wall of the crown body 1, and an outer flow channel 4 is opened on the outer wall of the crown body 1, a wear-resistant layer is provided on the inner wall of the crown body 1, and six blades 5 with odd and even numbers are provided on the outer wall of the crown body 1. The odd-numbered blade wings 5 ​​and the even-numbered blade wings 5 ​​are staggered, and the angle formed by any two adjacent odd-numbered blade wings 5 ​​and the even-numbered blade wings 5 ​​is 60°, and the odd-numbered blade wings 5 ​​are provided with sharp round teeth 6, first inverted eye teeth 7 and first strengthening teeth 8, and the even-numbered blade wings 5 ​​are provided with round teeth 9, second inverted eye teeth 10 and second strengthening teeth 11. The end of the crown body 1 is provided with a fan-shaped water eyelet 12 inclined from the inside to the outside.

[0028] Preferably, the envelope formed by the pointed round teeth 6 and the round teeth 9 on the blade wing 5 is a continuous wavy line with alternating peaks and valleys, and the height difference between the peaks and valleys is 1.5 mm.

[0029] This embodiment is a preferred implementation method. The envelope formed by the pointed round teeth 6 and the round teeth 9 on the blade 5 is a continuous wavy line with peaks and valleys, and the height difference between the peaks and valleys is 1.5 mm. The bottom hole morphology formed during the drilling process is a wavy shape with an annular ridge. This can suppress the lateral vibration of the drill bit during drilling, improve the working stability of the coring tool during drilling, protect the core, and improve the core quality and recovery rate.

[0030] Example 3 See also Figure 1-Figure 3 , a peak-valley cutting PDC drill bit suitable for coring hard plastic formations, includes a crown body 1 and a joint 2, the joint 2 is connected to the crown body 1, the crown body 1 is a hollow structure, an inner flow channel 3 is opened on the inner wall of the crown body 1, and an outer flow channel 4 is opened on the outer wall of the crown body 1, a wear-resistant layer is provided on the inner wall of the crown body 1, and six blades 5 with odd and even numbers are provided on the outer wall of the crown body 1. The odd-numbered blade wings 5 ​​and the even-numbered blade wings 5 ​​are staggered, and the angle formed by any two adjacent odd-numbered blade wings 5 ​​and the even-numbered blade wings 5 ​​is 60°, and the odd-numbered blade wings 5 ​​are provided with sharp round teeth 6, first inverted eye teeth 7 and first strengthening teeth 8, and the even-numbered blade wings 5 ​​are provided with round teeth 9, second inverted eye teeth 10 and second strengthening teeth 11. The end of the crown body 1 is provided with a fan-shaped water eyelet 12 inclined from the inside to the outside.

[0031] The envelope formed by the pointed round teeth 6 and the round teeth 9 on the blade 5 is a continuous wavy line with alternating peaks and valleys, and the height difference between the peaks and valleys is 1.5 mm.

[0032] The pointed round teeth 6 are located at the crest of the envelope, and the round teeth 9 are located at the trough of the envelope.

[0033] The pointed round teeth 6 include a fan-shaped top 13, a first fan-shaped inclined surface 14, a tooth portion 15 and a second fan-shaped inclined surface 16. The fan-shaped top 13, the first fan-shaped inclined surface 14, the tooth portion 15 and the second fan-shaped inclined surface 16 are integrally formed.

[0034] The width of the fan-shaped top 13 is 1.5 mm.

[0035] This embodiment is another preferred implementation method. The pointed round teeth 6 are located at the crest of the envelope line, and the round teeth 9 are located at the trough of the envelope line. Under certain drilling pressure conditions, the pointed round teeth 6 have strong drilling ability, can suppress the drill bit from slipping, and are easier to drill into the formation. The staggered arrangement of the round teeth 9 and the pointed round teeth 6 is easier to adapt to hard plastic formations, which can not only improve the cutting efficiency of hard plastic formations but also does not reduce the cutting efficiency of sandstone formations, and has good universality.

[0036] Example 4 See also Figure 1-Figure 3 , a peak-valley cutting PDC drill bit suitable for coring hard plastic formations, includes a crown body 1 and a joint 2, the joint 2 is connected to the crown body 1, the crown body 1 is a hollow structure, an inner flow channel 3 is opened on the inner wall of the crown body 1, and an outer flow channel 4 is opened on the outer wall of the crown body 1, a wear-resistant layer is provided on the inner wall of the crown body 1, and six blades 5 with odd and even numbers are provided on the outer wall of the crown body 1. The odd-numbered blade wings 5 ​​and the even-numbered blade wings 5 ​​are staggered, and the angle formed by any two adjacent odd-numbered blade wings 5 ​​and the even-numbered blade wings 5 ​​is 60°, and the odd-numbered blade wings 5 ​​are provided with sharp round teeth 6, first inverted eye teeth 7 and first strengthening teeth 8, and the even-numbered blade wings 5 ​​are provided with round teeth 9, second inverted eye teeth 10 and second strengthening teeth 11. The end of the crown body 1 is provided with a fan-shaped water eyelet 12 inclined from the inside to the outside.

[0037] The envelope formed by the pointed round teeth 6 and the round teeth 9 on the blade 5 is a continuous wavy line with alternating peaks and valleys, and the height difference between the peaks and valleys is 2 mm.

[0038] The pointed round teeth 6 are located at the crest of the envelope, and the round teeth 9 are located at the trough of the envelope.

[0039] Further preferably, the pointed round teeth 6 include a fan-shaped top 13, a first fan-shaped inclined surface 14, a tooth portion 15 and a second fan-shaped inclined surface 16, and the fan-shaped top 13, the first fan-shaped inclined surface 14, the tooth portion 15 and the second fan-shaped inclined surface 16 are integrally formed.

[0040] The width of the fan-shaped top 13 is 2 mm.

[0041] The included angle between the first sector-shaped inclined surface 14 and the second sector-shaped inclined surface 16 when obliquely projected onto the tooth surface of the tooth portion 15 is 75°.

[0042] The included angle between the first sector-shaped inclined surface 14 and the tooth surface of the tooth portion 15 is 20°.

[0043] The angle between the axis of the fan-shaped water hole 12 and the axis of the drill bit is 5°.

[0044] The deflection angle between the fan-shaped water eye 12 and the blade 5 is -2°.

[0045] This embodiment is another preferred implementation method. It adopts fan-shaped water holes 12 inclined from the inside to the outside, which can effectively fully cover and flush the mudstone adhering to the tooth surface, reduce repeated cutting, and achieve the effect of hydraulically assisted rock breaking.

[0046] Example 5 See also Figure 1-Figure 3 , a peak-valley cutting PDC drill bit suitable for coring hard plastic formations, includes a crown body 1 and a joint 2, the joint 2 is connected to the crown body 1, the crown body 1 is a hollow structure, an inner flow channel 3 is opened on the inner wall of the crown body 1, and an outer flow channel 4 is opened on the outer wall of the crown body 1, a wear-resistant layer is provided on the inner wall of the crown body 1, and six blades 5 with odd and even numbers are provided on the outer wall of the crown body 1. The odd-numbered blade wings 5 ​​and the even-numbered blade wings 5 ​​are staggered, and the angle formed by any two adjacent odd-numbered blade wings 5 ​​and the even-numbered blade wings 5 ​​is 60°, and the odd-numbered blade wings 5 ​​are provided with sharp round teeth 6, first inverted eye teeth 7 and first strengthening teeth 8, and the even-numbered blade wings 5 ​​are provided with round teeth 9, second inverted eye teeth 10 and second strengthening teeth 11. The end of the crown body 1 is provided with a fan-shaped water eyelet 12 inclined from the inside to the outside.

[0047] The envelope formed by the pointed round teeth 6 and the round teeth 9 on the blade 5 is a continuous wavy line with alternating peaks and valleys, and the height difference between the peaks and valleys is 2.5 mm.

[0048] The pointed round teeth 6 are located at the crest of the envelope, and the round teeth 9 are located at the trough of the envelope.

[0049] The pointed round teeth 6 include a fan-shaped top 13, a first fan-shaped inclined surface 14, a tooth portion 15 and a second fan-shaped inclined surface 16. The fan-shaped top 13, the first fan-shaped inclined surface 14, the tooth portion 15 and the second fan-shaped inclined surface 16 are integrally formed.

[0050] The width of the fan-shaped top 13 is 4.0 mm.

[0051] The included angle between the first sector-shaped inclined surface 14 and the second sector-shaped inclined surface 16 when obliquely projected onto the tooth surface of the tooth portion 15 is 80°.

[0052] The included angle between the first sector-shaped inclined surface 14 and the tooth surface of the tooth portion 15 is 30°.

[0053] The included angle between the axis of the fan-shaped water hole 12 and the axis of the drill bit is 10°.

[0054] The deflection angle between the fan-shaped water eye 12 and the blade 5 is 1°.

[0055] The blade 5 includes a cutting section 17 and a gauge section 18 , and the cutting section 17 and the gauge section 18 are integrally formed.

[0056] This embodiment is another preferred implementation method. By setting an inner flow channel 3 on the inner wall of the crown body 1 and an outer flow channel 4 on the outer wall of the crown body 1, double flow channels are formed, which can collaboratively discharge drill cuttings and improve drilling efficiency.

[0057] Example 6 See also Figures 1-4 , a peak-valley cutting PDC drill bit suitable for coring hard plastic formations, includes a crown body 1 and a joint 2, the joint 2 is connected to the crown body 1, the crown body 1 is a hollow structure, an inner flow channel 3 is opened on the inner wall of the crown body 1, and an outer flow channel 4 is opened on the outer wall of the crown body 1, a wear-resistant layer is provided on the inner wall of the crown body 1, and six blades 5 with odd and even numbers are provided on the outer wall of the crown body 1. The odd-numbered blade wings 5 ​​and the even-numbered blade wings 5 ​​are staggered, and the angle formed by any two adjacent odd-numbered blade wings 5 ​​and the even-numbered blade wings 5 ​​is 60°, and the odd-numbered blade wings 5 ​​are provided with sharp round teeth 6, first inverted eye teeth 7 and first strengthening teeth 8, and the even-numbered blade wings 5 ​​are provided with round teeth 9, second inverted eye teeth 10 and second strengthening teeth 11. The end of the crown body 1 is provided with a fan-shaped water eyelet 12 inclined from the inside to the outside.

[0058] The envelope formed by the pointed round teeth 6 and the round teeth 9 on the blade 5 is a continuous wavy line with alternating peaks and valleys, and the height difference between the peaks and valleys is 2.5 mm.

[0059] The pointed round teeth 6 are located at the crest of the envelope, and the round teeth 9 are located at the trough of the envelope.

[0060] The pointed round teeth 6 include a fan-shaped top 13, a first fan-shaped inclined surface 14, a tooth portion 15 and a second fan-shaped inclined surface 16. The fan-shaped top 13, the first fan-shaped inclined surface 14, the tooth portion 15 and the second fan-shaped inclined surface 16 are integrally formed.

[0061] The width of the fan-shaped top 13 is 4.0 mm.

[0062] More preferably, the included angle between the oblique projections of the first sector-shaped inclined surface 14 and the second sector-shaped inclined surface 16 on the tooth surface of the tooth portion 15 is 85°.

[0063] The included angle between the first sector-shaped inclined surface 14 and the tooth surface of the tooth portion 15 is 35°.

[0064] The included angle between the axis of the fan-shaped water hole 12 and the axis of the drill bit is 20°.

[0065] The deflection angle between the fan-shaped water eye 12 and the blade 5 is 2°.

[0066] The blade 5 includes a cutting section 17 and a gauge section 18 , and the cutting section 17 and the gauge section 18 are integrally formed.

[0067] The pointed crenulations 6 and the crenulations 9 are arranged on the cutting segment 17 .

[0068] The first inverted eye teeth 7 , the first reinforced teeth 8 , the second inverted eye teeth 10 and the second reinforced teeth 11 are all arranged on the gauge section 18 .

[0069] This embodiment is the best implementation method. The odd-numbered blades 5 and the even-numbered blades 5 are staggered to provide balanced cutting force and avoid stress concentration in the central area, thereby effectively protecting the core and improving the quality of core acquisition.

[0070] By specifically setting the crown body 1 as a hollow structure and providing a fan-shaped water eye 12 inclined from the inside to the outside on the end of the crown body 1, combined with the internal and external flow channels 4 and the pointed round teeth 6, round teeth 9, first inverted eye teeth 7 and second inverted eye teeth 10, the drilling ability and working stability of the drill bit in hard plastic formations can be greatly improved, so as to solve the problems of drill bit slippage, slow footage, rapid wear of cutting teeth and poor coring quality when drilling in hard plastic formations of existing drill bits, and improve the coring quality and drilling efficiency in hard plastic formations. The working principle of the present invention is as follows: By staggering the six blades 5, the odd and even blades 5 are evenly arranged at 60°, and the blades 5 with odd numbers are provided with sharp round teeth 6, first inverted eye teeth 7 and first reinforced teeth 8, and the blades 5 with even numbers are provided with round teeth 9, second inverted eye teeth 10 and second reinforced teeth 11, this differentiated cutting tooth combination can achieve efficient coring in hard plastic formations.

[0071] The pointed round teeth 6 of the odd-numbered blades 5 preferentially cut into the formation to form guide grooves, and the round teeth 9 of the even-numbered blades 5 follow up to trim the surface of the core column; the wear-resistant layer provided on the inner wall of the crown body 1 reduces core wear, and the double flow channels formed by the inner flow channel 3 on the inner wall of the crown body 1 and the outer flow channel 4 on the outer wall of the crown body 1 cooperate to discharge drill cuttings; the fan-shaped water eyelet 12 sprays directionally from the inside to the outside to flush the core surface and cool the tooth surface, and cooperates with the inverted eye teeth provided at the tail of the gauge section 18 to suppress vibration, and finally achieves continuous acquisition of high-integrity cores in a balance between strong impact and low disturbance, thereby ensuring the quality of coring.

[0072] In addition, a plum petal structure can be provided on the inner surface of the joint 2, which can not only effectively pass the drilling fluid, but also straighten the coring inner barrel, reduce the vibration of the inner barrel, and help improve the core recovery rate.

Claims

1. A peak-to-valley cutting PDC drill bit suitable for coring hard plastic formations, comprising a crown body (1) and a joint (2), wherein the joint (2) is connected to the crown body (1), and is characterized in that: The crown body (1) is a hollow structure. An inner flow channel (3) is provided on the inner wall of the crown body (1), and an outer flow channel (4) is provided on the outer wall of the crown body (1). A wear-resistant layer is provided on the inner wall of the crown body (1). Six blade wings (5) numbered in odd numbers and even numbers are provided on the outer wall of the crown body (1). The blade wings (5) numbered in odd numbers and the blade wings (5) numbered in even numbers are arranged alternately. The angle formed by any two adjacent blade wings (5) numbered in odd numbers and blade wings (5) numbered in even numbers is 60°. The blade wings (5) numbered in odd numbers are provided with sharp round teeth (6), first inverted eye teeth (7) and first strengthening teeth (8). The blade wings (5) numbered in even numbers are provided with round teeth (9), second inverted eye teeth (10) and second strengthening teeth (11). The end of the crown body (1) is provided with a fan-shaped water eyelet (12) inclined from the inside to the outside.

2. The peak-to-valley cutting PDC drill bit suitable for coring hard-plastic formations according to claim 1, characterized in that: The envelope formed by the pointed round teeth (6) and the round teeth (9) on the blade (5) is a continuous wavy line with alternating peaks and valleys, and the height difference between the peaks and valleys is at least 1.5 mm.

3. The peak-to-valley cutting PDC drill bit suitable for coring hard-plastic formations according to claim 1, characterized in that: The pointed round teeth (6) are located at the crest of the envelope, and the round teeth (9) are located at the trough of the envelope.

4. The peak-to-valley cutting PDC drill bit suitable for coring hard-plastic formations according to claim 1, characterized in that: The pointed round tooth (6) comprises a fan-shaped top (13), a first fan-shaped inclined surface (14), a tooth portion (15) and a second fan-shaped inclined surface (16); the fan-shaped top (13), the first fan-shaped inclined surface (14), the tooth portion (15) and the second fan-shaped inclined surface (16) are integrally formed.

5. The peak-to-valley cutting PDC drill bit suitable for coring hard-plastic formations according to claim 4, characterized in that: The width of the fan-shaped top (13) is 1.5-4.0 mm.

6. The peak-to-valley cutting PDC drill bit suitable for coring hard-plastic formations according to claim 4, characterized in that: The tooth surface included angle of the first sector-shaped inclined surface (14) and the second sector-shaped inclined surface (16) when obliquely projected onto the tooth portion (15) is 75-85°.

7. The peak-to-valley cutting PDC drill bit suitable for coring hard-plastic formations according to claim 6, characterized in that: The angle between the first sector-shaped inclined surface (14) and the tooth surface of the tooth portion (15) is 20-35°.

8. The peak-to-valley cutting PDC drill bit suitable for coring hard-plastic formations according to claim 1, characterized in that: The included angle between the axis of the fan-shaped water eye (12) and the axis of the drill bit is 5-20°.

9. The peak-to-valley cutting PDC drill bit suitable for coring hard-plastic formations according to claim 1, characterized in that: The deflection angle between the fan-shaped water eye hole (12) and the blade (5) is -2-2°.

10. The peak-to-valley cutting PDC drill bit suitable for coring in hard-plastic formations according to claim 1, characterized in that: The blade (5) comprises a cutting section (17) and a gauge-keeping section (18), and the cutting section (17) and the gauge-keeping section (18) are integrally formed.

11. The peak-to-valley cutting PDC drill bit suitable for coring hard-plastic formations according to claim 10, characterized in that: The pointed round teeth (6) and the round teeth (9) are arranged on the cutting section (17).

12. The peak-to-valley cutting PDC drill bit suitable for coring hard-plastic formations according to claim 10, characterized in that: The first inverted eye teeth (7), the first reinforced teeth (8), the second inverted eye teeth (10) and the second reinforced teeth (11) are all arranged on the gauge-keeping section (18).

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