Concave PDC drill bit

Abstract

Once a PDC drill bit is installed, it will cause the bit to lose its grip on the rock, causing it to leak inside and out.The PDC drill bit is more prone to rock damage than other drill bits, and it is more likely to cause a rock spill.

Description

Technical Field

[0001] The invention belongs to the technical field of oil drilling, and in particular relates to a concave PDC drill bit. Background Art

[0002] As shallow strata's oil and gas reserves decrease with exploitation, the proportion of deep and ultra-deep wells continues to increase year by year. During the drilling process of deep and ultra-deep wells, drilling speeds are slowed when encountering high-hardness, high-abrasiveness, and heterogeneous formations in deep sections, significantly increasing the cost of oil and gas field development. The pursuit of reducing oil and gas exploration and development costs places higher demands on drill bit design. Developing new drill bits suitable for deep, hard formations is an effective way to accelerate deep oil and gas exploration and development in my country.

[0003] PDC drill bits are primarily used in soft to medium-hard formations, but have poor adaptability in hard formations, prone to tooth chipping, chipping, and severe wear. In recent years, continuous improvements and innovations have been made in the cutting teeth, blade shape, and hydraulic design of PDC bits, which have improved the drilling performance of PDC bits in hard formations to a certain extent. However, they still struggle to meet the requirements for efficient rock breaking. Due to the difference in cutting capacity between the center and edge of the drill bit, the rock breaking speed at the center of the drill bit is slow, limiting the overall rock breaking speed. Furthermore, the center cutters are easily damaged, and the inability to increase the cutter density limits the overall life of the drill bit. Summary of the Invention

[0004] In view of the above-mentioned defects or deficiencies of the prior art, the present invention provides a concave PDC drill bit, which aims to solve the technical problem that the existing PDC drill bit still has difficulty in meeting the requirements of efficient rock breaking when encountering high-hard formations.

[0005] In order to achieve the above-mentioned objectives, the present invention provides a concave PDC drill bit, wherein the concave PDC drill bit includes a drill bit body, a core blade, a first auxiliary cutting tooth and a second auxiliary cutting tooth; the drill bit body has a plurality of circumferential blades; the core blade is arranged at the top core of the drill bit body and is formed with a first mounting side surface and a second mounting side surface on opposite sides, the first mounting side surface and the second mounting side surface respectively extending outward from the top of the drill bit body and being arranged obliquely close to each other; the first auxiliary cutting tooth and the second auxiliary cutting tooth are respectively arranged on the first mounting side surface and the second mounting side surface in a one-to-one correspondence, and the tooth tip height points are both lower than the tooth tip height points of the main cutting teeth of the crown of the circumferential blade.

[0006] In an embodiment of the present invention, the first mounting side surface and the second mounting side surface are intersecting at an end away from the top of the drill bit body, and the concave PDC drill bit further includes a core cutting tooth located at the intersection of the first mounting side surface and the second mounting side surface, and the tooth tip height of the core cutting tooth is lower than the tooth tip height of the main cutting tooth of the crown of the circumferential blade.

[0007] In an embodiment of the present invention, a mounting top surface connecting the first mounting side surface and the second mounting side surface is formed at the top end of the core blade, and the concave PDC drill bit also includes a core rock-breaking tooth extending vertically and arranged on the mounting top surface, and the tooth tip height of the core rock-breaking tooth is located on the center line of the drill bit body and is lower than the tooth tip height of the main cutting tooth of the crown of the circumferential blade.

[0008] In the embodiment of the present invention, the core rock-breaking teeth are conical teeth.

[0009] In an embodiment of the present invention, the number of the first auxiliary cutting teeth and the second auxiliary cutting teeth are both multiple, and the multiple first auxiliary cutting teeth are arranged in sequence at intervals along the extension direction of the first mounting side surface, and the multiple second auxiliary cutting teeth are arranged in sequence at intervals along the extension direction of the second mounting side surface.

[0010] In an embodiment of the present invention, a first rake surface of the first auxiliary cutting tooth on the core blade wing and a second rake surface of the second auxiliary cutting tooth on the core blade wing are arranged to face away from each other.

[0011] In an embodiment of the present invention, a first water hole and a second water hole are formed at the top of the drill body, separated from the core blade, and the first water hole is located on one side of the first rake face, and the second water hole is located on one side of the second rake face.

[0012] In the embodiment of the present invention, the drill bit body is provided with a nozzle between the crowns of any two adjacent circumferential blades.

[0013] In an embodiment of the present invention, the first auxiliary cutting teeth and the second auxiliary cutting teeth are both staggered with respect to the circumferential blades.

[0014] In an embodiment of the present invention, the concave PDC drill bit further includes a joint connected to the drill bit body, and an external thread is formed on the joint.

[0015] Through the above technical solution, the concave PDC drill bit provided by the embodiment of the present invention has the following beneficial effects:

[0016] The higher the cutting edge of the PDC drill bit, the lower the bit will move upwards, causing it to move more slowly up and down, which may cause the drill to move more slowly, This is because the PDC drill bit mainly uses a plurality of cutting teeth to move along the core blade, and a plurality of cutting teeth to move along the core blade.

[0017] Other features and advantages of the present invention will be described in detail in the following detailed description. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] The accompanying drawings are used to provide an understanding of the present invention and constitute a part of the specification. Together with the following detailed description, they are used to explain the present invention but do not constitute a limitation of the present invention. In the accompanying drawings:

[0019] Figure 1 1 is a schematic structural diagram of a composite concave PDC drill bit according to a first embodiment of the present invention from one perspective;

[0020] Figure 2 1 is a schematic structural diagram of a composite concave PDC drill bit according to the first embodiment of the present invention from another perspective;

[0021] Figure 3 1 is a schematic structural diagram of a composite concave PDC drill bit according to a second embodiment of the present invention from one perspective;

[0022] Figure 4 1 is a schematic structural diagram of a composite concave PDC drill bit according to a second embodiment of the present invention from another perspective;

[0023] Figure 5 It is a structural schematic diagram of the M-shaped well bottom according to the present invention.

[0024] Description of Reference Numerals

[0025] 1 drill bit body 11 first water hole

[0026] 12 Second water hole 13 Nozzle

[0027] 14 shackle slot

[0028] 2 Circumferential blade 21 Crown

[0029] 3 Main cutting teeth 4 Core blade

[0030] 41 Mounting top surface 42 First mounting side surface

[0031] 43 Second mounting side 44 First rake face

[0032] 45 Second rake face 5 Core rock breaking tooth

[0033] 6 First pair of cutting teeth 7 Second pair of cutting teeth

[0034] 8 Joint 9 Core cutting teeth DETAILED DESCRIPTION

[0035] The following is a detailed description of the specific embodiments of the present invention in conjunction with the accompanying drawings. It should be understood that the specific embodiments described herein are only used to illustrate and explain the present invention and are not intended to limit the present invention.

[0036] The concave type PDC drill bit according to the present invention will be described below with reference to the accompanying drawings.

[0037] See also Figure 1 and Figure 3 The present invention provides a concave PDC drill bit, wherein the concave PDC drill bit comprises:

[0038] The drill bit body 1 has a plurality of circumferential blades 2;

[0039] The core blade 4 is provided at the top core portion of the drill bit body 1 and is formed with a first mounting side surface 42 and a second mounting side surface 43 on opposite sides. The first mounting side surface 42 and the second mounting side surface 43 respectively extend outward from the top of the drill bit body 1 and are arranged close to each other at an angle; and

[0040] The first auxiliary cutting teeth 6 and the second auxiliary cutting teeth 7 are respectively arranged on the first mounting side surface 42 and the second mounting side surface 43 in a one-to-one correspondence, and the tooth tip heights are lower than the tooth tip heights of the main cutting teeth 3 of the crown portion 21 of the circumferential blade 2 .

[0041] When the above-mentioned concave PDC drill bit is used, since it includes a drill bit body 1, a core blade 4, a first auxiliary cutting tooth 6 and a second auxiliary cutting tooth 7, that is, in addition to the circumferential blade 2, the drill bit body 1 is also provided with a core blade 4 at the top, the first auxiliary cutting tooth 6 and the second auxiliary cutting tooth 7 are respectively provided on the first mounting side surface 42 and the second mounting side surface 43 of the core blade 4 in a one-to-one correspondence, and the tooth tip height is lower than the tooth tip height of the main cutting tooth 3 of the crown 21 of the circumferential blade 2. When the PDC drill bit breaks rock, the circumferential blade 2 is provided at the top of the drill bit body 1. The main cutting teeth 3 on the blade 2 break the outer circle of the bottom hole rock through plowing, shearing and grinding, forming a convex columnar structure in the core of the rock, releasing the confining pressure in the center of the bottom hole rock, weakening the rock strength in the center, and reducing the energy required for rock breaking in the center. Subsequently, the first auxiliary cutting teeth 6 and the second auxiliary cutting teeth 7 on the core blade 4 with the highest point of the tooth tip lower than the main cutting teeth 3 can break the convex rock in the center through the shear and splitting coupling effect, thereby achieving the effects of efficient rock breaking, reducing the lateral vibration of the drill bit, and enhancing the dynamic stability of the drill bit.

[0042] It should be noted that the crown 21 of the circumferential blade 2 extends to the top of the drill body 1, so that the top core of the drill body 1 is concave, and the core blade 4 is located in this concave space. At the same time, a plurality of main cutting teeth 3 can be provided on one circumferential blade 2, and there can be more than two main cutting teeth 3 on the crown 21 of the circumferential blade 2, and the tooth tip height of the first auxiliary cutting tooth 6 and the second auxiliary cutting tooth 7 on the core blade 4 must be at least lower than the tooth tip height of the main cutting tooth 3 at the highest position on the circumferential blade 2. The tooth tip height is the highest cutting point of the tooth, and under the cooperative cutting of the main cutting teeth 3 of the circumferential blade 2 and the first auxiliary cutting teeth 6 and the second auxiliary cutting teeth 7 of the core blade 4, the following can be formed. Figure 5 In addition, the main cutting teeth 3, the first auxiliary cutting teeth 6 and the second auxiliary cutting teeth 7 on the circumferential blade 2 can all be set as PDC cutting teeth.

[0043] like Figure 1 and Figure 2 As shown, in the first embodiment of the present invention, the first mounting side surface 42 and the second mounting side surface 43 intersect at one end away from the top of the drill bit body 1. That is, the core blade 4 can be configured as a triangle, with the first mounting side surface 42 and the second mounting side surface 43 being the two waists of the triangle. The concave PDC drill bit also includes a core cutting tooth 9 located at the intersection of the first mounting side surface 42 and the second mounting side surface 43. The tooth tip of the core cutting tooth 9 is lower than the tooth tip of the main cutting tooth 3 on the crown 21 of the circumferential blade 2. In other words, the core cutting tooth 9 is disposed at the tip of the triangle, thereby concentrating the load on the core cutting tooth 9. Specifically, the core cutting tooth 9 can also be configured as a PDC cutting tooth, and the core cutting tooth 9 is arranged on the center plane of the drill bit body 1.

[0044] like Figure 3 and Figure 4 As shown, in the second embodiment of the present invention, the top of the core blade 4 is formed with a mounting top surface 41 connecting a first mounting side surface 42 and a second mounting side surface 43. The concave PDC drill bit also includes a core rock breaker tooth 5 extending vertically from the mounting top surface 41. The tooth tip of the core rock breaker tooth 5 is located on the centerline of the drill bit body 1 and is lower than the tooth tip of the primary cutting tooth 3 of the crown 21 of the circumferential blade 2. The formation of the mounting top surface 41, the first mounting side surface 42, and the second mounting side surface 43 facilitates the arrangement of the core rock breaker tooth 5, the first secondary cutting tooth 6, and the second secondary cutting tooth 7. In addition, the core blade 4 is designed to taper from the bottom end (the top end of the drill bit body 1) toward the top end, thereby concentrating the load on the tip of the core rock breaker tooth 5. Furthermore, the vertically extending core rock breaker tooth 5 has a higher drilling efficiency than the transversely arranged core cutting tooth 9. Specifically, the shape of the core blade 4 can be an isosceles trapezoid, the mounting top surface 41 is the upper base of the isosceles trapezoid, and the first mounting side surface 42 and the second mounting side surface 43 are two waist sides of the isosceles trapezoid respectively.

[0045] In an embodiment of the present invention, the core rock-breaking teeth 5 may be conical teeth. Specifically, as the PDC drill bit rotates, the conical teeth are more likely to concentrate the load on the rock at a single point than a single PDC cutting tooth. This concentrated load, combined with the high cutting strength and wear resistance of the conical teeth, enables drilling through difficult and complex formations that conventional PDC drill bits cannot adapt to. This also improves the drill bit's wear resistance and significantly increases the drilling speed. More specifically, the centerline of the conical teeth is collinear with the centerline of the drill bit body 1. Of course, the present invention is not limited to this, and the conical teeth may also be axe-shaped teeth.

[0046] In the embodiment of the present invention, the number of the first auxiliary cutting teeth 6 and the second auxiliary cutting teeth 7 can be multiple, and the multiple first auxiliary cutting teeth 6 are arranged in a row and spaced apart in sequence along the extension direction of the first mounting side surface 42, and the multiple second auxiliary cutting teeth 7 are arranged in a row and spaced apart in sequence along the extension direction of the second mounting side surface 43, thereby improving the tooth density of the core of the drill bit body 1, so that the core rock can be crushed with smaller rock breaking energy, thereby improving the rock breaking efficiency and increasing the cutting strength and service life of the PDC drill bit.

[0047] In an embodiment of the present invention, the first front cutting surface 44 of the first auxiliary cutting tooth 6 on the core blade 4 and the second front cutting surface 45 of the second auxiliary cutting tooth 7 on the core blade 4 are arranged to be back-to-back with each other, that is, the first front cutting surface 44 of the first auxiliary cutting tooth 6 on the core blade 4 can become the back cutting surface of the second auxiliary cutting tooth 7 on the core blade 4, and the second front cutting surface 45 of the second auxiliary cutting tooth 7 on the core blade 4 can become the back cutting surface of the first auxiliary cutting tooth 6 on the core blade 4, thereby realizing bidirectional rock breaking and facilitating chip removal.

[0048] In this embodiment of the present invention, a first water hole 11 and a second water hole 12 are formed at the top of the drill bit body 1, spaced apart from the core blades 4. The first water hole 11 is located on one side of the first rake face 44, and the second water hole 12 is located on one side of the second rake face 45. The addition of the first water hole 11 and the second water hole 12 facilitates cleaning the core rock-breaking teeth 5, the first auxiliary cutting teeth 6, and the second auxiliary cutting teeth 7 on the core blades 4, thereby preventing mud packing.

[0049] In this embodiment of the present invention, the drill bit body 1 is provided with nozzles 13 between the crowns 21 of any two adjacent circumferential blades 2. The main cutters 3 on the circumferential blades 2 are the primary rock-breaking structure of the PDC drill bit. The main cutters 3 grind the bottom of the wellbore through shearing, destruction, and formation of the wellbore. The nozzles 13 between the crowns 21 of the two adjacent circumferential blades 2 provide better cooling, lubrication, and cleaning for the main cutters 3.

[0050] In the embodiment of the present invention, the first and second auxiliary cutting teeth 6, 7 are staggered relative to the circumferential blades 2. That is, the first and second auxiliary cutting teeth 6, 7 are positioned relative to the gap between two adjacent circumferential blades 2, thereby ensuring uniformity of the cutting load at the same time and avoiding stress concentration. Furthermore, the nozzle 13 is located within the gap, allowing the nozzle 13 to cool, lubricate, and clean the first and second auxiliary cutting teeth 6, 7.

[0051] In the embodiment of the present invention, the number of the circumferential blades 2 can be six, and the six circumferential blades 2 are evenly spaced around the circumference of the drill body 1. Of course, the present invention is not limited thereto, and the number of the circumferential blades 2 can be set according to specific needs.

[0052] In this embodiment of the present invention, the concave PDC drill bit further includes a connector 8 connected to the drill bit body 1. The connector 8 is formed with external threads to facilitate removable installation with a drill tool. Furthermore, the connector 8 and the drill bit body 1 can be connected by a weld or integrally formed. The drill bit body 1 is also provided with a shackle groove 14.

[0053] In the description of the present invention, it should be understood that the terms "first" and "second" are used for descriptive purposes only and should not be understood to indicate or imply relative importance or implicitly specify the number of the technical features indicated. Therefore, a feature defined as "first" or "second" may explicitly or implicitly include at least one of such features. In the description of the present invention, "plurality" means at least two, for example, two, three, etc., unless otherwise specifically defined.

[0054] In the present invention, unless otherwise specified or limited, the terms "installed," "connected," "connect," "fixed," etc. should be understood in a broad sense. For example, they can refer to fixed connection, detachable connection, or integration; mechanical connection, electrical connection, or communication; direct connection or indirect connection through an intermediate medium; internal communication between two elements or interaction between two elements, unless otherwise specified. Those skilled in the art will understand the specific meanings of the above terms in the present invention based on specific circumstances.

[0055] In the description of this specification, the reference terms "one embodiment", "some embodiments", "example", "specific example", or "some examples" mean that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described can be combined in any one or more embodiments or examples in a suitable manner. In addition, those skilled in the art can combine and combine different embodiments or examples described in this specification and features of different embodiments or examples without contradiction.

[0056] Although the embodiments of the present invention have been shown and described above, it will be understood that the above embodiments are illustrative and are not to be construed as limitations on the present invention. A person skilled in the art may change, modify, replace and modify the above embodiments within the scope of the present invention.

Claims

1. A concave PDC drill bit, characterized in that: include: A drill bit body (1) having a plurality of circumferential blades (2), wherein the crowns (21) of the circumferential blades (2) extend to the top end of the drill bit body (1), so that the top end core of the drill bit body (1) is concavely arranged; A core blade (4) is provided at the top core of the drill bit body (1) and is provided with a first mounting side surface (42) and a second mounting side surface (43) on opposite sides, wherein the first mounting side surface (42) and the second mounting side surface (43) respectively extend outward from the top of the drill bit body (1) and are arranged close to each other at an angle; and The first auxiliary cutting teeth (6) and the second auxiliary cutting teeth (7) are respectively arranged on the first mounting side surface (42) and the second mounting side surface (43) in a one-to-one correspondence, and the tooth tip heights are both lower than the tooth tip heights of the main cutting teeth (3) of the crown (21) of the circumferential blade (2); The first mounting side surface (42) and the second mounting side surface (43) both extend to the top of the core blade (4), and the top of the core blade (4) is provided with a core cutting tooth (9) or a core rock-breaking tooth (5), so that the load is concentrated on the top of the core blade (4), and the tooth tip height of the core cutting tooth (9) or the core rock-breaking tooth (5) is lower than the tooth tip height of the main cutting tooth (3) of the crown (21) of the circumferential blade (2), so that an M-shaped well bottom can be machined using the concave PDC drill bit; The number of the first auxiliary cutting teeth (6) and the number of the second auxiliary cutting teeth (7) are both plural, and the plurality of the first auxiliary cutting teeth (6) are sequentially spaced along the extension direction of the first mounting side surface (42), and the plurality of the second auxiliary cutting teeth (7) are sequentially spaced along the extension direction of the second mounting side surface (43).

2. The concave PDC drill bit according to claim 1, characterized in that: The first mounting side surface (42) and the second mounting side surface (43) are intersectingly arranged at an end away from the top of the drill bit body (1), and the concave PDC drill bit further comprises a core cutting tooth (9) located at the intersection of the first mounting side surface (42) and the second mounting side surface (43), wherein the tooth tip height of the core cutting tooth (9) is lower than the tooth tip height of the main cutting tooth (3) of the crown (21) of the circumferential blade (2).

3. The concave PDC drill bit according to claim 1, characterized in that: The top end of the core blade (4) is formed with a mounting top surface (41) connecting the first mounting side surface (42) and the second mounting side surface (43). The concave PDC drill bit further comprises a core rock-breaking tooth (5) vertically extending from the mounting top surface (41). The tooth tip height of the core rock-breaking tooth (5) is located on the center line of the drill bit body (1) and is lower than the tooth tip height of the main cutting tooth (3) of the crown (21) of the circumferential blade (2).

4. The concave PDC drill bit according to claim 3, characterized in that: The core rock-breaking teeth (5) are conical teeth.

5. The concave PDC drill bit according to any one of claims 1 to 4, characterized in that: The first rake surface (44) of the first auxiliary cutting tooth (6) on the core blade (4) and the second rake surface (45) of the second auxiliary cutting tooth (7) on the core blade (4) are arranged to face away from each other.

6. The concave PDC drill bit according to claim 5, characterized in that: A first water hole (11) and a second water hole (12) are provided at the top end of the drill bit body (1) and spaced apart from the core blade (4), wherein the first water hole (11) is located on one side of the first rake face (44), and the second water hole (12) is located on one side of the second rake face (45).

7. The concave PDC drill bit according to any one of claims 1 to 4, characterized in that: The drill bit body (1) is provided with a nozzle (13) between the crowns (21) of any two adjacent circumferential blades (2).

8. The concave PDC drill bit according to any one of claims 1 to 4, characterized in that: The first auxiliary cutting teeth (6) and the second auxiliary cutting teeth (7) are both staggered with respect to the circumferential blade (2).

9. The concave PDC drill bit according to any one of claims 1 to 4, characterized in that: The concave PDC drill bit further comprises a joint (8) connected to the drill bit body (1), and an external thread is formed on the joint (8).

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