A PDC drill bit suitable for large-diameter coring in hard rock

Abstract

The present invention discloses a PDC drill bit suitable for large-diameter core drilling in hard rock, belonging to the field of geological drilling technology. The bit comprises a drill body and a drill crown connected to the drill body. The bit is characterized by having multiple cutting structures spaced circumferentially at intervals at the bottom of the drill crown. Each cutting structure comprises a bottom wing and multiple bottom composite plates and reinforcing teeth specially arranged on the bottom wing. A vertical groove is provided at the center of the inner wall of each bottom wing, and an alloy material is welded into the groove to form an internal diameter guarantee. The drill crown is provided with spiral side wings corresponding to the bottom wing at the periphery, and each side wing is provided with multiple side composite plates and reinforcing teeth to form an external diameter guarantee. A bottom and side water trough are provided between the bottom wing and the side wings of the drill crown, and an elliptical bottom water jet hole is provided in the bottom water trough. The use of this device improves the efficiency of hard rock formation crushing and reduces the cost of the drill bit.

Description

Technical Field

[0001] The invention belongs to the technical field of geological drilling, and in particular relates to a PDC drill bit suitable for large-diameter drilling and coring of hard rocks. Background Art

[0002] Energy and environment are the two major issues in today's society. As society pays more and more attention to environmental protection, my country has proposed the "dual carbon" goal of reaching the peak of carbon emissions by 2030 and achieving carbon neutrality before 2060. Adjustment of energy structure is imperative.

[0003] Geothermal energy, a form of thermal energy stored within the Earth, boasts large reserves, widespread distribution, green, low-carbon, recyclable, stable, and reliable characteristics. It is a viable and competitive clean energy source. The development and utilization of geothermal energy can reduce greenhouse gas emissions and improve the ecological environment. It has become a new direction for energy structural transformation and is of great significance to my country's energy structure adjustment, energy security, and the achievement of its "dual carbon" goals.

[0004] Coring is the only means of obtaining physical data from strata, and is of great significance for understanding the characteristics of underground heat reservoirs and evaluating and planning geothermal resources. With the exploration, development, and utilization of geothermal resources, these exploration and development are gradually moving deeper. In deep geothermal resource exploration, it is often necessary to drill into rock formations with higher hardness. At the same time, to meet the requirements of later testing and development and utilization, geothermal exploration wells are generally designed with larger diameters. In large-diameter coring drilling in hard rock, the same diamond-impregnated drill bits used in small-diameter hard rock coring drilling are used. However, due to their large diameter and thick bottom lip, drilling efficiency is low and bit costs are high. Conventional PDC drill bits are not suitable for hard rock formations. Summary of the Invention

[0005] In order to solve the above problems, the present invention adopts the following technical solutions:

[0006] A PDC drill bit suitable for large-diameter coring in hard rock, comprising a drill bit body, a drill bit crown connected to the drill bit body, and a plurality of cutting structures arranged at intervals along the circumference at the bottom of the drill bit crown. Each cutting structure comprises a bottom wing and a plurality of bottom surface composite sheets and a plurality of bottom surface reinforcing teeth arranged on the bottom wing.

[0007] A first vertical groove is provided at the center of the inner wall of each bottom wing, and alloy material is welded in the first vertical groove;

[0008] The periphery of the drill crown is provided with a plurality of side wings corresponding to the bottom wings, and each of the side wings is provided with a plurality of side composite sheets and a plurality of side reinforcing teeth arranged at intervals;

[0009] A bottom water trough is provided between two adjacent bottom wings, and bottom water spray holes are provided in the bottom water trough. A side water trough is provided between two adjacent side wings.

[0010] Furthermore, the number of the bottom surface composite sheets and the bottom surface reinforcement teeth on each bottom wing is the same, and the bottom surface reinforcement teeth and the bottom surface composite sheets are arranged in a one-to-one correspondence along the cutting direction.

[0011] Furthermore, a plurality of side composite sheets are provided on the cutting side of the side wing and are located at the bottom of the side wing, and a plurality of side reinforcing teeth are provided on the side wing around the side composite sheets.

[0012] Furthermore, the bottom lip surface profile of the cutting structure is a short parabola.

[0013] Furthermore, the plurality of bottom surface composite sheets on each bottom wing are arranged in a herringbone pattern.

[0014] Furthermore, a second vertical groove is milled near the center of the chip side of the bottom wing, and each bottom wing is provided with three bottom surface composite pieces, of which two bottom surface composite pieces are arranged on both sides of the second vertical groove, and the bottom surface composite piece located in the middle is arranged in a backward manner.

[0015] Furthermore, the side wings are spiral-shaped.

[0016] Furthermore, the bottom water tank has the same width inside and outside.

[0017] Beneficial effects:

[0018] 1. The PDC drill bit bottom wing designed in the present invention has a second vertical groove milled near the center of the chip side of the bottom surface, which realizes the backward layout of the bottom middle composite plate, which is beneficial to protecting the bottom middle composite plate, increasing the stability of the drill bit rotation and improving the rock crushing efficiency.

[0019] 2. The PDC drill bit bottom surface reinforcement teeth are arranged in a herringbone shape, which is beneficial to improving the protection performance of the bottom surface composite sheet and improving the impact resistance of the bottom surface composite sheet.

[0020] 3. The PDC drill bit flanks designed in the present invention are designed to have a spiral shape, which is conducive to maintaining the stability of the drill bit during rotation, thereby reducing the additional impact force on the composite piece caused by unstable rotation during the rotation process, thereby increasing the life of the composite piece and thus increasing the service life of the drill bit.

[0021] 4. The inner diameter maintenance of the PDC drill bit designed by the present invention adopts a welded alloy material, and the side composite sheets and the side reinforcement teeth of the outer diameter maintenance are also welded with an alloy material, which is beneficial to improving the diameter maintenance performance of the drill bit and increasing the service life of the drill bit in hard rock formations.

[0022] 5. The water groove on the bottom surface of the PDC drill bit designed in the present invention is designed to have equal width inside and outside, and the shape of the bottom water jet hole is designed to be elliptical, which is conducive to timely carrying the rock chips carved by the cutting structure.

[0023] 6. The bottom lip profile of the PDC drill bit designed in the present invention is designed to be a short parabola, which has good impact resistance and is suitable for use in hard rock formations.

[0024] 7. The bottom composite sheet and side composite sheet of the PDC drill bit designed by the present invention are both made of impact-resistant diamond composite sheets with a composite layer thickness of more than 3 mm. The diamond composite layer of the composite sheet is decobalted and the decobaltization thickness is not less than 0.5 mm, further enhancing the impact resistance of the composite sheet to better meet the drilling needs of hard rock formations.

[0025] 8. The PDC drill bit designed in the present invention adopts a bottom water jet design, which reduces the scouring of the core by the drilling fluid circulation and is beneficial to protecting the core. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 This is a cross-sectional view of a PDC drill bit suitable for large-diameter coring in hard rock.

[0027] Figure 2 A side view of a PDC drill bit suitable for large-diameter coring in hard rock.

[0028] Figure 3 This is a schematic diagram of the bottom lip structure of a PDC drill bit suitable for large-diameter coring in hard rock.

[0029] Among them, 1. drill body, 2. side wings, 3. bottom lip surface profile, 4. bottom wings, 5. bottom water spray hole, 6. bottom water groove, 7. side water groove, 8. bottom composite piece, 9. bottom reinforcing tooth, 10. side composite piece, 11. side reinforcing tooth, 12. inner diameter protection, 13. connecting thread. DETAILED DESCRIPTION

[0030] Example 1

[0031] refer to Figure 1 - Figure 3 A PDC drill bit suitable for large-diameter drilling and coring in hard rock, comprising a drill bit body 1, a drill bit crown connected to the drill bit body 1, and comprising:

[0032] The bottom of the drill crown is provided with multiple cutting structures spaced apart along the circumferential direction, each cutting structure comprising a bottom wing 4 and multiple bottom surface composite sheets 8 and multiple bottom surface reinforcing teeth 9 arranged on the bottom wing 4;

[0033] A first vertical groove is milled at the center of the inner wall of each bottom wing 4, and alloy material is welded into the first vertical groove;

[0034] The periphery of the drill crown is provided with a plurality of side wings 2 corresponding to the bottom wings 4, and each side wing 2 is provided with a plurality of side composite sheets 10 and a plurality of side reinforcing teeth 11 arranged at intervals;

[0035] Preferably, alloy material is welded between the side composite sheet 10 and the side reinforcing teeth 11 to enhance the outer diameter protection performance.

[0036] A bottom water trough 6 is provided between each of the adjacent bottom wings 4 , and a bottom water spray hole 5 is provided in each of the bottom water troughs 6 . A side water trough is provided between each of the adjacent side wings 2 .

[0037] In this embodiment, the number of bottom composite sheets 8 and bottom reinforcement teeth 9 on each bottom wing 4 is the same, and the bottom reinforcement teeth 8 and the bottom composite sheets 9 are arranged in a one-to-one correspondence along the cutting direction.

[0038] In this embodiment, a plurality of side composite sheets 10 are disposed on the cutting side of the side wing 2 and located at the bottom of the side wing 2 , and a plurality of side reinforcing teeth 11 are disposed on the side wing 2 around the side composite sheets 10 .

[0039] In this embodiment, a connecting thread 13 in the form of a rectangular buckle is provided at the upper end of the drill body 1 for connecting to an upper core drilling tool;

[0040] In this embodiment, a first vertical groove is milled out at the center of the inner wall of each bottom wing 4 and an alloy material is welded into the first vertical groove to form an inner diameter guard 12;

[0041] A plurality of side composite sheets 10 and a plurality of side reinforcing teeth 11 are provided on the side wing 2 to form an outer diameter protection.

[0042] Preferably, the core drill 1 is made of a rigid body, which is convenient for design and processing.

[0043] During specific implementation, the composite sheet groove is first milled out on the bottom surface of the bottom wing 4, and then the bottom composite sheet 8 and the bottom reinforcement teeth 9 are inlaid.

[0044] In this embodiment, alloy material is welded between the side composite sheets 10 and the side reinforcing teeth 11 to enhance the outer diameter protection performance.

[0045] In this embodiment, the bottom lip surface profile 3 of the cutting structure is in the shape of a short parabola.

[0046] The lip surface profile of this chip structure has strong impact resistance and is suitable for use in hard rock formations.

[0047] In this embodiment, the multiple bottom surface composite sheets 8 on each bottom wing 4 are arranged in a triangular shape.

[0048] In this embodiment, a second vertical groove is milled near the center of the chip side of the bottom wing 4 to achieve the backward arrangement of the bottom surface composite piece 8 in the middle of the bottom lip surface.

[0049] Preferably, the number of bottom surface composite sheets 8 and bottom surface reinforcing teeth 9 on each bottom wing 4 is the same, and one bottom surface reinforcing tooth 9 is provided behind each bottom surface composite sheet 8 .

[0050] Preferably, three bottom surface composite sheets 8 are provided on each bottom wing 4, wherein two bottom surface composite sheets 8 are arranged on both sides of the second vertical groove, and the bottom surface composite sheet 8 located in the middle is arranged in a retreating manner.

[0051] The bottom surface composite piece 8 in the middle of the bottom wing 4 is arranged in a backward manner, which is beneficial to increasing the stability of the drill bit rotation and improving the rock crushing efficiency.

[0052] Preferably, the bottom water spray hole 5 is designed to be elliptical.

[0053] In this embodiment, the side wings 2 are spiral-shaped, which helps the drill bit to remain stable during rotation and avoids damage to the composite sheet caused by additional impact due to unstable rotation of the drill bit.

[0054] Preferably, the bottom composite sheet 8 and the side composite sheet 10 both use impact-resistant diamond composite sheets with a composite layer thickness of more than 3 mm, and the diamond composite layer of the composite sheet is decobalted, with a decobalting thickness of not less than 0.5 mm, to further enhance the impact resistance of the composite sheet to better adapt to the drilling needs of hard rock formations.

[0055] In this embodiment, the bottom water trough has the same width inside and outside, so as to facilitate carrying the rock chips carved by the cutting structure.

[0056] Preferably, the side water trough 7 is designed to be spiral along with the side wing 2 .

[0057] The above description is merely a preferred embodiment of the present invention and does not limit the technical scope of the present invention. Therefore, any minor modifications, equivalent changes and modifications made to the above embodiments based on the technical essence of the present invention still fall within the scope of the technical solution of the present invention.

Claims

1. A PDC drill bit suitable for large-diameter coring of hard rock, comprising a drill bit body and a drill bit crown connected to the drill bit body, characterized in that: The bottom of the drill crown is provided with a plurality of cutting structures spaced apart along the circumferential direction, each of the cutting structures comprising a bottom wing and a plurality of bottom surface composite sheets and a plurality of bottom surface reinforcing teeth arranged on the bottom wing; A first vertical groove is provided at the center of the inner wall of each bottom wing, and alloy material is welded in the first vertical groove; The periphery of the drill crown is provided with a plurality of side wings corresponding to the bottom wings, and each of the side wings is provided with a plurality of side composite sheets and a plurality of side reinforcing teeth arranged at intervals; A bottom water trough is provided between two adjacent bottom wings, and a bottom water spray hole is provided in each bottom water trough, and a side water trough is provided between two adjacent side wings; The multiple bottom surface composite sheets on each bottom wing are arranged in a triangular shape, and a second vertical groove is milled near the center of the chip side of the bottom wing. Three bottom surface composite sheets are set on each bottom wing, of which two bottom surface composite sheets are arranged on both sides of the second vertical groove, and the bottom surface composite sheet in the middle is arranged in a backward manner.

2. The PDC drill bit suitable for large-diameter coring in hard rock according to claim 1, characterized in that: The number of the bottom surface composite sheets and the bottom surface reinforcement teeth on each bottom wing is the same, and the bottom surface reinforcement teeth and the bottom surface composite sheets are arranged in a one-to-one correspondence along the cutting direction.

3. The PDC drill bit suitable for large-diameter coring in hard rock according to claim 1, characterized in that: A plurality of side composite sheets are arranged on the cutting side of the side wing and located at the bottom of the side wing. A plurality of side reinforcing teeth surround the side composite sheets and are arranged on the side wing.

4. The PDC drill bit suitable for large-diameter coring in hard rock according to claim 1, characterized in that: The bottom lip surface profile of the cutting structure is a short parabola.

5. The PDC drill bit suitable for large-diameter coring in hard rock according to claim 1, characterized in that: The flanks are helical in shape.

6. The PDC drill bit suitable for large-diameter coring in hard rock according to claim 1, characterized in that: The bottom water tank has the same width inside and outside.

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