Concave type drill bit

Abstract

The utility model belongs to the technical field of drilling tools, and particularly relates to a concave drill bit which comprises a drill bit body, core cutting teeth and a plurality of cutting blades, and a central area is formed on the end face of the drilling end of the drill bit body; the core cutting teeth are arranged within the central region; the multiple cutting blades are arranged on the drilling end at intervals in the circumferential direction and located outside the center area. More cutting teeth are arranged on the parts, deviating from the central axis of the drill bit body in the radial direction, of the cutting blades, and less cutting teeth are arranged on the parts, deviating from the end face of the drilling end in the axial direction, of the cutting blades. When the drill bit body rotates, due to the fact that the number of the cutting teeth on the end face of the drilling end and the number of the cutting teeth on the outer edge of the drilling end are different, the rock breaking efficiency of the end face of the drilling end is lower than that of the outer edge of the drilling end. According to the drilling end, the center area is formed on the end face of the drilling end, the tooth distribution density of the end face of the drilling end is increased through the core cutting teeth arranged in the center area, and therefore the rock breaking efficiency of the end face of the drilling end is improved.

Description

Technical Field

[0001] The present application belongs to the technical field of drilling tools, and specifically relates to a concave drill bit. Background Art

[0002] With the continuous deepening of oil exploration and development, shallow and easily exploitable oil and gas resources are becoming less and less. Seeking oil and gas resources in deep strata and complex geological conditions is gradually becoming an important task in current marine and land exploration and development. Deep hard rock usually exhibits properties such as high strength, high hardness, strong abrasiveness, severe heterogeneity and poor drillability during the drilling process. Existing rock breaking tools and drilling methods for drilling tools generally have problems such as slow drilling speed, short drill bit life, long drilling cycle and high drilling cost, which directly restrict the drilling speed of deep wells and ultra-deep wells and the overall benefits of exploration and development.

[0003] In the prior art, a plurality of cutting blades are arranged at the drilling end of the drill bit, and a plurality of cutting teeth are arranged on the cutting blades to break the rock. With respect to the above-mentioned related art, the tooth density of the cutting blades near the center of the drill bit is relatively small, resulting in a slow rock breaking speed in the center of the drill bit. Utility Model Content

[0004] The purpose of the present application is to provide a concave drill bit, aiming to increase the tooth density in the center of the drill bit.

[0005] On one hand, the present application provides a concave drill bit, comprising:

[0006] A drill body extends in an axial direction, wherein two ends of the drill body in the axial direction are respectively a drilling end and a connecting end, and an end surface of the drilling end is formed with a central area;

[0007] core cutting teeth disposed within the central region; and

[0008] A plurality of cutting blades are circumferentially spaced apart and arranged on the drilling end and outside the central area.

[0009] In some embodiments, the number of the core cutting teeth is plural and the core cutting teeth are spaced apart along a first annular direction, and the first annular direction takes the center of the central area as the center of the circle.

[0010] In some embodiments, the core cutting teeth are divided into multiple groups and the multiple groups of core cutting teeth are arranged along different circumferential directions, and the different circumferential directions all take the center of the central area as the center of the circle.

[0011] In some embodiments, the recessed drill bit further comprises a central conical tooth disposed at the center of the central region.

[0012] In some embodiments, the cutting blade comprises:

[0013] a cutting portion, arranged on the end surface of the drilling end and extending along the axial direction, the cutting portion being provided with a plurality of edge cutting teeth; and

[0014] A connecting portion is arranged on the outer periphery of the drilling end, and the connecting portion extends along the axial direction and is connected to the cutting portion.

[0015] In some embodiments, the cutting portion is further provided with a plurality of internal cutting teeth, the plurality of edge cutting teeth are arranged on the front side of the cutting portion along the circumferential direction, and the plurality of internal cutting teeth are arranged on the rear side of the edge cutting teeth along the circumferential direction.

[0016] In some embodiments, a blade nozzle is provided on the cutting portion.

[0017] In some embodiments, a diameter-protecting structure is provided on the connecting portion, and the diameter-protecting structure includes diameter-protecting protrusions arranged at intervals along the axial direction and / or the circumferential direction.

[0018] In some embodiments, the drilling end of the drill bit body is provided with an outer drill bit nozzle and an inner drill bit nozzle, the outer drill bit nozzle is located outside the central area, and the inner drill bit nozzle is located within the central area.

[0019] In some embodiments, the number of the inner drill bit nozzles is multiple and the multiple inner drill bit nozzles are arranged at intervals along a second annular direction, and the second annular direction takes the center of the central area as the center of the circle; and / or

[0020] There are multiple outer drill bit nozzles, and the multiple outer drill bit nozzles are arranged at intervals along a third annular direction, and the third annular direction takes the center of the central area as the center of the circle.

[0021] Through the above technical solution, the concave drill bit provided by the present application has the following beneficial effects:

[0022] The drilling end of the drill bit body is provided with a plurality of cutting blades, and a side of the cutting blade radially away from the center of the drill bit body is provided with more cutting teeth for cutting the rock contacted by the edge of the drill bit body, and a side of the cutting blade axially away from the drill bit body is provided with fewer cutting teeth for cutting the rock contacted by the center of the drill bit body. In the present application, a central area is formed on the end face of the drilling end of the drill bit body, and the rock contacted by the center of the drill bit body is cut by the core cutting teeth arranged in the central area, thereby increasing the tooth density in the central part of the drill bit body, and then improving the drilling speed of the concave drill bit.

[0023] Other features and advantages of the embodiments of the present application will be described in detail in the subsequent detailed description. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] The accompanying drawings are used to provide a further understanding of the embodiments of the present application and constitute a part of the specification. Together with the following specific embodiments, they are used to explain the embodiments of the present application, but do not constitute a limitation on the embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on the structures shown in these drawings without creative work. In the drawings:

[0025] Figure 1 It is a structural schematic diagram of a first concave drill bit according to a specific embodiment of the present application;

[0026] Figure 2 A top view of a first concave drill bit according to a specific embodiment of the present application;

[0027] Figure 3 It is a structural schematic diagram of a second concave drill bit according to a specific embodiment of the present application;

[0028] Figure 4 It is a top view of the second concave drill bit according to the specific embodiment of the present application.

[0029] Description of Reference Numerals

[0030] 100 Concave drill bit 1 Drill bit body

[0031] 11 Drilling end 12 Connection end

[0032] 13 Central area 14 Cylindrical part

[0033] 15 Cone 2 Cutting blade

[0034] 21 Connecting part 22 Cutting part

[0035] 23 Edge cutting teeth 24 Diameter protection structure

[0036] 25 Internal cutting teeth 26 Knife wing nozzle

[0037] 3 Core cutting teeth 4 Center conical teeth

[0038] 5 Outer drill nozzle 6 Inner drill nozzle DETAILED DESCRIPTION

[0039] The specific implementation of the present application is described in detail below in conjunction with the accompanying drawings. It should be understood that the specific implementation described here is only used to illustrate and explain the present application, and is not used to limit the present application.

[0040] The concave drill bit 100 according to the present application will be described below with reference to the accompanying drawings.

[0041] like Figures 1 to 4As shown, a specific embodiment of the present application provides an inwardly concave drill bit 100, comprising a drill bit body 1, core cutting teeth 3 and a plurality of cutting blades 2, wherein the drill bit body 1 extends axially, and the two ends of the drill bit body 1 along the axial direction are respectively a drilling end 11 and a connecting end 12, and a central area 13 is formed on the end face of the drilling end 11; the core cutting teeth 3 are arranged in the central area 13; and the plurality of cutting blades 2 are arranged on the drilling end 11 at intervals along the circumferential direction and are located outside the central area 13.

[0042] A plurality of cutting teeth are arranged on the cutting blade 2, wherein more cutting teeth are arranged at the portion of the cutting blade 2 radially away from the central axis of the drill bit body 1, and fewer cutting teeth are arranged at the portion of the cutting blade 2 axially away from the end face of the drilling end 11. When the drill bit body 1 rotates, due to the difference in the number of cutting teeth at the end face of the drilling end 11 and the outer edge of the drilling end 11, the rock breaking efficiency of the end face of the drilling end 11 is lower than the rock breaking efficiency of the outer edge of the drilling end 11. In the present application, a central area 13 is formed at the end face of the drilling end 11, and the tooth density of the end face of the drilling end 11 is increased by the core cutting teeth 3 arranged in the central area 13, thereby improving the rock breaking efficiency of the end face of the drilling end 11, and then matching the rock breaking efficiency of the end face of the drilling end 11 with the outer edge of the drilling end 11 to improve the drilling speed of the concave drill bit 100.

[0043] It should be noted that in the present application, unless otherwise specified, the directional term "inner" refers to the side close to the central axis of the drill bit body 1, "outer" refers to the side away from the central axis of the drill bit body 1, "front" refers to the side that contacts the rock first along the circumferential direction, and "rear" refers to the side that contacts the rock later along the circumferential direction.

[0044] In some embodiments, the drill body 1 includes a conical portion 15 and a cylindrical portion 14 connected along the axial direction, the centers of the conical portion 15 and the cylindrical portion 14 are both located on the central axis of the drill body 1, the conical portion 15 and the cylindrical portion 14 both extend axially, the conical portion 15 includes a large diameter end face and a small diameter end face, wherein the large diameter end face is connected to the cylindrical portion 14, and the central area 13 is located on the small diameter end face.

[0045] Specifically, the central area 13 is a circular area with the center located on the central axis. The cutting blades 2 are arranged outside the central area 13 to avoid interference between the cutting blades 2 and the core cutting teeth 3, thereby improving the rationality of the structural arrangement of the concave drill bit 100.

[0046] Preferably, there are multiple core cutting teeth 3 and the multiple core cutting teeth 3 are arranged at intervals along the first annular direction, with the center of the central area 13 as the center of the circle. By arranging multiple core cutting teeth 3 along the first annular direction, it is ensured that the cutting amount of each core cutting tooth 3 is basically equal, so that the cutting amount at each position of the central area 13 is the same.

[0047] Furthermore, the core cutting teeth 3 are divided into multiple groups and the multiple groups of core cutting teeth 3 are arranged along different annular directions, and the different annular directions are all centered on the center of the central area 13. By arranging the core cutting teeth 3 along multiple annular directions, multiple core cutting teeth 3 are arranged in the central area 13 as much as possible, thereby improving the tooth density while ensuring the same cutting amount at each position in the central area 13, thereby making the cutting surface of the drilling end 11 smooth.

[0048] In some embodiments, the recessed drill bit 100 further includes a central conical tooth 4 disposed at the center of the central region 13 .

[0049] Specifically, the center conical tooth 4 extends axially and forms a sharp corner at one end of the end face away from the drilling end 11. The center conical tooth 4 performs an impact and stretching effect on the rock, thereby improving the rock breaking efficiency of the end face of the drilling end 11, and the torque and lateral vibration generated by the impact and stretching effect on the drill bit body 1 are relatively stable, thereby effectively improving the stability of the drill bit body 1, and further extending the service life of the concave drill bit 100.

[0050] Among them, the generation of torque and lateral vibration is the reaction force of rock on the drill bit body 1. The generation of torque is the reaction force of rock on the drill bit body 1 along the circumferential direction, and the generation of lateral vibration is the reaction force of rock on the drill bit body 1 along the radial direction. The impact stretching effect makes the value of the reaction force fluctuate little.

[0051] In some embodiments, the cutting blades 2 are evenly spaced along the circumferential direction, and the cutting blades 2 include a cutting portion 22 and a connecting portion 21 , wherein the connecting portion 21 is arranged on the periphery of the drilling end 11 , and the cutting portion 22 is arranged on the end face of the drilling end 11 .

[0052] Specifically, the connecting portion 21 is arranged on the outer peripheral wall of the cylindrical portion 14 of the drill body 1 and radially protrudes from the outer peripheral wall of the cylindrical portion 14. The connecting portion 21 extends axially to the large diameter end surface of the truncated cone portion 15 and is connected to the cutting portion 22. The outer wall surface of the cutting portion 22 in the radial direction is an arcuate surface, and the inner wall surface of the cutting portion 22 in the radial direction extends axially and connects the outer wall surface of the cutting portion 22 in the radial direction and the end surface of the drilling end 11. The projection of the outer wall surface in the axial direction is located outside the central area 13, so as to avoid interference with the core cutting teeth 3. The cutting portion 22 is provided with a plurality of edge cutting teeth 23, which are arranged on the front side of the arcuate surface, and the plurality of edge cutting teeth 23 are arranged at intervals along the extension direction of the front side.

[0053] During drilling operations, the edge cutting teeth 23 first contact the rock and break the rock while the core cutting teeth 3 do not contact the rock. As the edge cutting teeth 23 advance, the core cutting teeth 3 gradually approach the bottom of the well and form a convex bottom in the well, thereby releasing the stress at the center of the bottom of the well, so that the rock at the center of the bottom of the well is subjected to tensile stress and the range is larger than that of a conventional bottom of the well; and, the rock at the bottom of the well is in a damaged or easily damaged state, so that the rock at the bottom of the well is more easily damaged by the core cutting teeth 3 and the center conical teeth 4, thereby improving the drilling speed of the concave drill bit 100.

[0054] Furthermore, the connecting portion 21 is provided with a diameter-protecting structure 24 radially protruding from the connecting portion 21. During drilling operations, the drill rod drives the drill bit body 1 to rotate, the cutting portion 22 first contacts the rock and breaks the rock, and the connecting portion 21 enters the well with the drill bit body 1, and the diameter-protecting structure 24 on the connecting portion 21 rotates with the drill bit body 1 to grind the well wall, thereby ensuring the flatness of the well wall and avoiding the well wall directly contacting the connecting portion 21 and causing wear, thereby extending the service life of the concave drill bit 100.

[0055] Preferably, the diameter-protecting structure 24 includes diameter-protecting protrusions arranged at intervals along the axial direction and / or the circumferential direction. The construction process of the diameter-protecting protrusions is simple, which is convenient for production and application. The shape of the diameter-protecting protrusions can be cylindrical, cubic, truncated cone, etc.

[0056] Preferably, the cutting portion 22 is also provided with a plurality of internal cutting teeth 25, a plurality of edge cutting teeth 23 are arranged on the front side of the cutting portion 22, and a plurality of internal cutting teeth 25 are arranged on the rear side of the edge cutting teeth 23. The internal cutting teeth 25 are arranged to increase the tooth density on the cutting blade 2, thereby improving the rock breaking efficiency of the cutting blade 2, and the operating intensity of a single cutting tooth is reduced by simultaneously breaking rocks with the internal cutting teeth 25 and the edge cutting teeth 23, thereby extending the service life of the concave drill bit 100.

[0057] Furthermore, the outer wall surface of the cutting portion 22 is covered with multiple rows of internal cutting teeth 25, and each row of internal cutting teeth 25 includes multiple internal cutting teeth 25 arranged at intervals along the circumferential direction, thereby effectively utilizing the arrangement space of the cutting portion 22 to prevent individual internal cutting teeth 25 from falling off during operation, thereby ensuring that the concave drill bit 100 can continue to operate.

[0058] It should be noted that the size of the cutting wing 2 varies with the number of internal cutting teeth 25. When a single cutting wing 2 needs to be arranged with multiple internal cutting teeth 25, the size of the cutting wing 2 along the circumferential direction increases and the number of cutting wings 2 decreases.

[0059] Preferably, a blade nozzle 26 is provided on the cutting portion 22, and the spray hole of the blade nozzle 26 is opened on the outer wall surface of the cutting portion 22. The water passage of the blade nozzle 26 is connected to the drill body 1, the connecting portion 21, the cutting portion 22 and the spray hole in sequence. The blade nozzle 26 on the cutting blade 2 is used to spray and clean the edge cutting teeth 23 and the internal cutting teeth 25, thereby preventing mud packing on the cutting blade 2.

[0060] Furthermore, the blade nozzle 26 is arranged in a one-to-one correspondence with the cutting blade 2, and the blade nozzle 26 is located between the plurality of internal cutting teeth 25, so that the blade nozzle 26 can cover all the internal cutting teeth 25 and the edge cutting teeth 23 on each cutting blade 2. The structure of the blade nozzle 26 is well known to those skilled in the art, and does not belong to the core improvement part of the present application, and thus will not be described in detail here.

[0061] In some embodiments, the drilling end 11 of the drill bit body 1 is provided with an outer drill bit nozzle 5 and an inner drill bit nozzle 6, the outer drill bit nozzle 5 is located outside the central area 13, and the inner drill bit nozzle 6 is located inside the central area 13, the drill bit body 1 is flushed through the outer drill bit nozzle 5 and the core cutting teeth 3 are flushed through the inner drill bit nozzle 6, thereby preventing mud balling on the drill bit body 1.

[0062] Specifically, the outer drill nozzle 5 is disposed on the outer peripheral wall of the truncated cone portion 15 of the drill body 1 , and the inner drill nozzle 6 is disposed on the small-diameter end surface of the truncated cone portion 15 of the drill body 1 .

[0063] Preferably, there are multiple inner drill bit nozzles 6 and the multiple inner drill bit nozzles 6 are arranged at intervals along the second annular direction, the second annular direction takes the center of the central area 13 as the center of the circle, the multiple inner drill bit nozzles 6 are arranged symmetrically, and the flushing range of the multiple inner drill bit nozzles 6 covers the entire central area 13.

[0064] Preferably, there are multiple outer drill bit nozzles 5 and the multiple outer drill bit nozzles 5 are arranged at intervals along the third annular direction, the third annular direction takes the center of the central area 13 as the center of the circle, the multiple outer drill bit nozzles 5 are arranged symmetrically, and the flushing range of the multiple outer drill bit nozzles 5 covers the part of the drill bit body 1 outside the central area 13.

[0065] Furthermore, the number of the outer drill bit nozzles 5 is the same as the number of the cutting blades 2, and each outer drill bit nozzle 5 is arranged between every two adjacent cutting blades 2. The outer drill bit nozzle 5 is used to flush the area between the cutting blades 2, thereby preventing mud balling from occurring in the area between the cutting blades 2.

[0066] Those skilled in the art will appreciate that the number and arrangement positions of the outer drill nozzles 5 and the inner drill nozzles 6 are determined according to the coverage of a single outer drill nozzle 5 and an inner drill nozzle 6 .

[0067] In the specific embodiment of the present application, two types of concave drill bits 100 are provided, one of which is a concave distributed tooth drill bit, and the other is a concave special-shaped drill bit. The concave distributed tooth drill bit includes five cutting blades 2, and the cutting blades 2 are provided with edge cutting teeth 23 as the first-level cutting structure, and the central area 13 is provided with core cutting teeth 3 and central conical teeth 4 as the second-level cutting structure. The concave special-shaped drill bit includes three cutting blades 2, and the cutting blades 2 are provided with edge cutting teeth 23 and internal cutting teeth 25 as the first-level cutting structure, and the central area 13 is provided with core cutting teeth 3 and central conical teeth 4 as the second-level cutting structure.

[0068] During drilling operations, the first-stage cutting structure first contacts the rock and performs shear damage on the rock. As drilling goes deeper, the second-stage cutting structure contacts the rock again, wherein the center conical teeth 4 drill into the rock to create cracks in the center rock at the bottom of the well, and the core cutting teeth 3 perform shear damage on the center rock.

[0069] It should be noted that the tooth shape of the cutting teeth can be conical teeth, axe-shaped teeth, etc., and the material is PDC (Polycrystalline Diamond Compact). Various tooth shapes all fall within the protection scope of this application, and a drill bit inlaid with PDC cutting teeth is a PDC drill bit.

[0070] In the description of the present application, it should be understood that the terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one of the features. In the description of the present application, "plurality" means at least two, such as two, three, etc., unless otherwise clearly and specifically defined.

[0071] In this application, unless otherwise clearly specified and limited, the terms "installed", "connected", "connected", "fixed" and the like should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection, an electrical connection, or communication with each other; it can be a direct connection, or an indirect connection through an intermediate medium, it can be the internal connection of two elements or the interaction relationship between two elements, unless otherwise clearly defined. For ordinary technicians in this field, the specific meanings of the above terms in this application can be understood according to specific circumstances.

[0072] In the description of this specification, the description with reference to the terms "one embodiment", "some embodiments", "example", "specific example", or "some examples" etc. means 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 application. 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 may be combined in any one or more embodiments or examples in a suitable manner. In addition, those skilled in the art may combine and combine the different embodiments or examples described in this specification and the features of the different embodiments or examples, without contradiction.

[0073] Although the embodiments of the present application have been shown and described above, it can be understood that the above embodiments are exemplary and cannot be understood as limitations on the present application. Ordinary technicians in the field can change, modify, replace and modify the above embodiments within the scope of the present application.

Claims

1. A concave drill bit, characterized in that: include: A drill body (1) extends in an axial direction, and two ends of the drill body (1) in the axial direction are respectively a drilling end (11) and a connecting end (12), and an end surface of the drilling end (11) is formed with a central area (13); core cutting teeth (3) arranged in said central region (13); and A plurality of cutting blades (2) are arranged at intervals along the circumferential direction on the drilling end (11) and are located outside the central area (13).

2. The concave drill bit according to claim 1, characterized in that: The number of the core cutting teeth (3) is plural, and the core cutting teeth (3) are arranged at intervals along a first annular direction, wherein the first annular direction takes the center of the central area (13) as the center of the circle.

3. The concave drill bit according to claim 1, characterized in that: The core cutting teeth (3) are divided into multiple groups, and the multiple groups of core cutting teeth (3) are arranged along different annular directions, and the different annular directions all take the center of the central area (13) as the center of the circle.

4. The concave drill bit according to claim 1, characterized in that: The concave drill bit (100) further comprises a central conical tooth (4), wherein the central conical tooth (4) is arranged at the center of the central area (13).

5. The concave drill bit according to claim 1, characterized in that: The cutting blade (2) comprises: a cutting portion (22) arranged on the end surface of the drilling end (11) and extending along the axial direction, wherein the cutting portion (22) is provided with a plurality of edge cutting teeth (23); and A connecting portion (21) is arranged on the outer periphery of the drilling end (11), and the connecting portion (21) extends along the axial direction and is connected to the cutting portion (22).

6. The concave drill bit according to claim 5, characterized in that: The cutting portion (22) is also provided with a plurality of internal cutting teeth (25), the plurality of edge cutting teeth (23) are arranged on the front side of the cutting portion (22) along the circumferential direction, and the plurality of internal cutting teeth (25) are arranged on the rear side of the edge cutting teeth (23) along the circumferential direction.

7. The concave drill bit according to claim 5, characterized in that: The cutting portion (22) is provided with a blade nozzle (26).

8. The concave drill bit according to claim 5, characterized in that: The connecting portion (21) is provided with a diameter-protecting structure (24), and the diameter-protecting structure (24) comprises diameter-protecting protrusions arranged at intervals along the axial direction and / or the circumferential direction.

9. The concave drill bit according to claim 1, characterized in that: The drilling end (11) of the drill bit body (1) is provided with an outer drill bit nozzle (5) and an inner drill bit nozzle (6), wherein the outer drill bit nozzle (5) is located outside the central area (13), and the inner drill bit nozzle (6) is located inside the central area (13).

10. The concave drill bit according to claim 9, characterized in that: The number of the inner drill nozzles (6) is plural and the plurality of inner drill nozzles (6) are arranged at intervals along a second annular direction, wherein the second annular direction takes the center of the central area (13) as the center of the circle; and / or The number of the outer drill bit nozzles (5) is plural, and the plurality of the outer drill bit nozzles (5) are arranged at intervals along a third annular direction, wherein the third annular direction takes the center of the central area (13) as the center of the circle.

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