PDC (Polycrystalline Diamond Compact) mixed-inlaid drill bit for well drilling in hard formation with strong abrasiveness

Abstract

The invention discloses a PDC (Polycrystalline Diamond Compact) mixed-inlaid drill bit for well drilling in a strong-abrasiveness hard formation, which is used for prolonging the service life of the drill bit and improving the well drilling efficiency. The drill bit comprises a drill bit body and a plurality of blades. The plurality of blades are arranged on the crown part of the drill bit main body, a chip groove is formed between every two adjacent blades, and a fan-shaped water channel is arranged on each chip groove; a cutting area is arranged on the blade, a first cutting unit and a second cutting unit are arranged on the cutting area in the front-back direction in the drilling direction, the second cutting unit is embedded in the rear portion of the first cutting unit and connected with the first cutting unit, and after the first cutting unit is abraded, the second cutting unit is embedded in the rear portion of the first cutting unit and connected with the second cutting unit. The second cutting unit is used for replacing rock breaking; the central area of the crown part is provided with a cone inner cone structure which is concave inwards, an inner water channel is arranged on the cone inner cone structure, and a triangular polycrystalline Balas is embedded on the conical surface of the cone inner cone structure.

Description

Technical Field

[0001] This application relates to the field of oil drilling tools technology, and in particular to a PDC hybrid drill bit for drilling in highly abrasive hard formations. Background Technology

[0002] In oil and gas drilling operations, the drill bit, as the core tool that directly contacts and breaks rock formations, is a key factor determining drilling efficiency, cycle time, and cost. As exploration and development extend to deeper and unconventional areas, the formation conditions faced by drill bits are becoming increasingly complex, placing higher demands on the rock-breaking efficiency, wear resistance, and adaptability of drill bits to different operating conditions.

[0003] Especially when encountering highly abrasive hard formations such as gravelly quartz sandstone, basalt, and granite during drilling, the lithology exhibits characteristics of "relatively drillable upper part and extremely hard lower part" or "frequent alternation of soft and hard rock" with well depth. Existing conventional drill bits, such as PDC drill bits or natural diamond surface-mounted drill bits, can maintain a certain mechanical drilling rate in the upper formations, but once they enter highly abrasive hard rock sections, their cutting teeth wear accelerates rapidly, and their mechanical properties deteriorate quickly. While impregnated diamond drill bits, which are designed solely to improve wear resistance, have a longer lifespan, their mechanical drilling rate is relatively low when drilling into upper formations, making it difficult to meet the requirements of efficient operation.

[0004] Regardless of the type of drill bit mentioned above, when facing hard, abrasive formations, the central area of ​​the drill bit crown often suffers from insufficient density and weak wear resistance due to limited tooth space. This makes it prone to premature core wear failure, a phenomenon known as "core wear." This not only ends the drill bit's service life but also leads to frequent tripping and bit replacements, severely hindering the overall drilling progress.

[0005] Based on this, this application proposes a PDC hybrid insert drill bit for drilling in highly abrasive hard formations to solve the above-mentioned technical problems. Summary of the Invention

[0006] To address the aforementioned technical problems, this application provides a PDC hybrid insert drill bit for drilling in highly abrasive hard formations, which can improve drill bit lifespan and drilling efficiency.

[0007] The technical solution provided in this application is described below: This application provides a PDC hybrid drill bit for drilling in highly abrasive hard formations, comprising: The drill bit body and multiple cutting blades; The plurality of cutting blades are disposed on the crown of the drill bit body, and a chip removal groove is formed between two adjacent cutting blades. A fan-shaped water channel is provided on the chip removal groove. The blade is provided with a cutting area, and a first cutting unit and a second cutting unit are arranged in the cutting area along the drilling direction. The second cutting unit is embedded behind the first cutting unit and connected to the first cutting unit. When the first cutting unit is worn, the second cutting unit takes over to break the rock. The central region of the crown is provided with an inwardly recessed conical inner cone structure, the inner cone structure is provided with an inner water channel, and triangular polycrystalline balas are inlaid on the conical surface of the inner cone structure.

[0008] Optionally, the first cutting unit uses PDC profiled teeth for cutting, and the second cutting unit uses impregnated teeth for cutting.

[0009] Optionally, the cutting teeth used in the first cutting unit and the cutting teeth used in the second cutting unit are both alternately arranged with PDC special-shaped teeth and impregnated teeth; Furthermore, along the drilling direction, the impregnated tooth in the second cutting unit is arranged behind each PDC profile tooth in the first cutting unit, and the PDC profile tooth in the second cutting unit is arranged behind each impregnated tooth in the first cutting unit.

[0010] Optionally, the first cutting unit uses PDC profiled teeth and impregnated teeth arranged in an alternating pattern, and the second cutting unit uses impregnated teeth.

[0011] Optionally, the difference between the protrusion height of the PDC profile tooth and the protrusion height of the impregnated tooth is 0.8-1.2 mm.

[0012] Optionally, the PDC profiled tooth includes a 7D tooth, which includes three first inclined surfaces, three wide facets, and a central plane; The angle between each of the first inclined planes and the central plane is 12-15 degrees; The angle between each of the wide facets and the central plane is 5-8 degrees; The width of each of the wide facets is 1.5-3 mm.

[0013] Optionally, the PDC profiled tooth includes an arc ridge tooth, which includes an arc surface and two second inclined surfaces; The radius of the arc surface is 50-70mm, and the narrowest width is 1.5-3mm; The included angle between the two second inclined planes is 135-155 degrees.

[0014] Optionally, the cone apex half angle β of the cone structure inside the cone is 30-45 degrees.

[0015] Optionally, the size of the cutting teeth in the second cutting unit is smaller than the size of the cutting teeth in the first cutting unit.

[0016] Optionally, the triangular polycrystalline balas has a tooth density of 1-3 grains / carat and is arranged in a three-level concentric ridge setting.

[0017] As can be seen from the above technical solutions, this application has the following beneficial effects: This application provides several blades on the crown of the drill bit body, with a cutting area on each blade. A first cutting unit and a second cutting unit are arranged on the cutting area, positioned front and back along the drilling direction. The second cutting unit is connected behind the first cutting unit. During drilling, when the first cutting unit is worn down by the rock formation, the second cutting unit takes over, breaking the rock. This improves service life and reduces the frequency of drill bit replacements. Compared to traditional drill bits, this application combines long service life with high drilling speed, meeting the demands of today's efficient operations.

[0018] By setting an inwardly recessed conical internal cone structure in the central area of ​​the crown of the drill bit body, and inlaying triangular polycrystalline balas on the conical surface of the internal cone structure, rock breaking can be performed on the rock strata in the core area as well, reducing the situation where the drill bit core wears out first and also reducing the occurrence of "core removal". Attached Figure Description

[0019] Figure 1 This is a schematic diagram of a PDC hybrid drill bit for drilling in highly abrasive hard formations according to this application; Figure 2 This is a top view schematic diagram of a PDC hybrid drill bit for drilling in highly abrasive hard formations according to this application; Figure 3 This is a cross-sectional schematic diagram of a PDC hybrid drill bit for drilling in highly abrasive hard formations according to this application; Figure 4 This is a partially enlarged schematic diagram of a PDC hybrid drill bit for drilling in highly abrasive hard formations according to this application; Figure 5 This is a schematic diagram of the 7D tooth of this application; Figure 6 This is a schematic diagram of the arc ridge tooth of this application; Figure 7 This is a schematic diagram of the figure-eight shaped composite cutting structure for continuous rock breaking in this application. Figure 8 This is a schematic diagram of the crescent-shaped teeth of this application; In the figure, the drill bit body is 01, the cutter blade is 02, the chip removal groove is 03, the fan-shaped water channel is 04, the cone structure inside the cone is 05, the internal water channel is 06, the PDC special-shaped tooth is 07, the impregnated tooth is 08, the 7D tooth is 09, the first bevel is 10, the wide facet is 11, the center plane is 12, the teardrop-shaped thickened diamond layer is 13, the arc ridge tooth is 14, the arc surface is 15, the second bevel is 16, and the welding mark groove is 17. Detailed Implementation

[0020] In this application, the terms "upper", "lower", "left", "right", "front", "rear", "top", "bottom", "inner", "outer", "middle", "vertical", "horizontal", "lateral", "longitudinal" and other terms indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only used to describe the relative positional relationship between the components or parts and do not specifically limit the specific installation orientation of each component or part.

[0021] Furthermore, in addition to indicating location or positional relationship, some of the aforementioned terms may also have other meanings. For example, the term "above" may also be used in some cases to indicate a certain dependency or connection relationship. Those skilled in the art can understand the specific meaning of these terms in this application based on the specific circumstances.

[0022] Furthermore, the terms "installation," "setup," "equipped with," "connection," and "linked" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral structure; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium, or an internal connection between two devices, components, or parts. Those skilled in the art can understand the specific meaning of these terms in this application based on the specific circumstances.

[0023] Furthermore, the structures, proportions, sizes, etc., drawn in the accompanying drawings of this application are only used to complement the content disclosed in the specification for those skilled in the art to understand and read, and are not intended to limit the conditions under which this application can be implemented. Therefore, they have no substantial technical significance. Any modification to the structure, change in the proportional relationship, or adjustment of the size, without affecting the effects and purposes that this application can produce, should still fall within the scope of the technical content disclosed in this application.

[0024] The technical solutions of this application will now be clearly and completely described with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0025] To address the shortcomings of traditional drill bits, such as short service life and susceptibility to core-hunting issues that affect drilling progress when dealing with rock formations exhibiting varying hardness with different drilling depths, this application proposes a PDC hybrid-insertion drill bit for drilling in highly abrasive and hard formations. This design aims to improve drill bit life and drilling efficiency. The specific implementation structure of this application is described below: See Figures 1 to 8 This application provides an embodiment of a PDC hybrid drill bit for drilling in highly abrasive hard formations, the embodiment comprising: The drill bit body 01 and multiple cutter wings 02 are arranged on the crown of the drill bit body 01. A chip removal groove 03 is formed between two adjacent cutter wings 02, and a fan-shaped water channel 04 is provided on the chip removal groove 03. A cutting area is provided on the cutter wing 02. A first cutting unit and a second cutting unit are arranged in the cutting area along the drilling direction. The second cutting unit is embedded behind the first cutting unit and connected to the first cutting unit. When the first cutting unit is worn, the second cutting unit takes over the rock breaking. The central area of ​​the crown is provided with an inwardly recessed conical internal cone structure 05. An internal water channel 06 is provided on the conical internal cone structure 05. Triangular polycrystalline balas are inlaid on the conical surface of the conical internal cone structure 05.

[0026] The front end of the drill bit body 01 is the crown, and the rear end is the connector for connecting the drill string. There are multiple cutter wings 02 on the drill bit body 01 (usually 6-12), which are radially fixed on the crown of the drill bit body 01. They are the main structure that supports the cutting teeth. The cutter wings 02 are integrally formed with the crown of the drill bit body 01 or welded to it.

[0027] The space formed between two adjacent blades 02 is a cuttings chute 03, used for the upward return of cuttings. A fan-shaped water channel 04 is provided in the cuttings chute 03, and a fan-shaped nozzle is provided in the fan-shaped water channel 04. The fan-shaped nozzle is connected to the internal water channel 06 system inside the drill bit body 01 for transporting drilling fluid.

[0028] The cutting area on the blade 02 is equipped with a first cutting unit and a second cutting unit. The first cutting unit and the second cutting unit are arranged adjacent to each other on the blade 02. The second cutting unit is embedded in and attached to the rear of the first cutting unit. The two have complementary outlines and together form a continuous rock-breaking working face (approximately "8" shaped).

[0029] Along the drilling direction, the first and second cutting units are interconnected to form a composite cutting structure. This composite cutting structure, through a "primary in front, backup in back" arrangement, resolves the contradiction between high drilling speed and long service life that a single type of cutting element cannot simultaneously achieve. The first cutting unit serves as the primary rock-breaking element, undertaking the majority of rock-breaking work in the initial stage of drilling, aiming to achieve a high mechanical drilling speed. The second cutting unit serves as the backup rock-breaking element, entering service after the first unit has worn down to a certain extent, aiming to extend the overall service life of the drill bit.

[0030] The inner cone structure 05 is located in the central region of the crown of the drill bit body 01. The inner cone structure 05 is an inwardly recessed conical surface. Triangular polycrystalline ballast is inlaid on the conical surface of the inner cone structure 05. The triangular polycrystalline ballast is fixed to the conical surface of the inner cone by sintering or brazing.

[0031] During the drilling process, the rock strata corresponding to the cone structure 05 inside the cone will be broken by the triangular polycrystalline ballast fixed on the conical concave surface, thus improving the wear resistance of the core and reducing the occurrence of "core removal".

[0032] An inner water channel 06 is provided in the central area of ​​the crown of the drill bit body 01. The inner water channel 06 penetrates the surface of the inner cone structure 05 of the cone and is also used to transport drilling fluid to cool the cutting teeth, carry cuttings, and clean the bottom of the well. There are 3 inner water channels 06.

[0033] In addition to the cutting area, the cutter wing 02 is also equipped with a gauge protection area, which is located behind the cutter wing 02 along the drilling direction (i.e., around the outside of the drill bit body 01). The gauge protection area is also inlaid with one or more rows of natural diamonds to form a reinforced gauge protection layer to ensure the quality of the wellbore.

[0034] During drilling, the first cutting unit initially contacts and breaks the rock formation. As drilling progresses, especially in highly abrasive and hard formations, the first cutting unit gradually wears down. When it wears to a predetermined depth, the second cutting unit, originally embedded behind it, begins to contact the formation and takes over the rock-breaking function. The cone-shaped internal cone structure 05 in the central region of the crown, due to its larger surface area and optimized tooth distribution, significantly improves the density and wear resistance of the core cutting element (triangular polycrystalline balas), thereby delaying core failure, supporting uniform wear across the entire drill bit working face, and extending the effective life of the entire drill bit.

[0035] Please continue reading. Figure 7 and Figure 8 The cutting teeth of the first cutting unit are the main cutting teeth, and the cutting teeth of the second cutting unit are inlaid auxiliary crescent-shaped teeth that are combined with the cutting teeth of the first cutting unit to form a figure-eight-shaped composite cutting structure that can continuously break rocks.

[0036] In this embodiment, a plurality of blades 02 are provided on the crown of the drill bit body 01, and a cutting area is provided on the blades 02. A first cutting unit and a second cutting unit are arranged on the cutting area. The first cutting unit and the second cutting unit are arranged front and back along the drilling direction. The second cutting unit is connected to the rear of the first cutting unit. During the drilling process, when the first cutting unit is worn by the rock formation, the second cutting unit takes over to break the rock. This can improve the service life and reduce the number of times the drill bit needs to be replaced. Compared with traditional drill bits, this application has both a long service life and a high drilling speed, which meets the current demand for efficient operation.

[0037] By setting an inwardly recessed conical internal cone structure 05 in the central area of ​​the crown of the drill bit body 01, and inlaying triangular polycrystalline balas on the conical surface of the conical internal cone structure 05, the rock strata in the core area can also be broken, reducing the situation where the drill bit core wears out first and also reducing the occurrence of "core removal".

[0038] In an optional embodiment, the first cutting unit uses PDC profiled teeth 07, and the second cutting unit uses impregnated teeth 08.

[0039] Based on the aforementioned first and second cutting units, the following specific limitations are made: the first cutting unit uses PDC profiled teeth 07 throughout; the second cutting unit uses inlaid teeth 08 throughout. In this embodiment, the PDC profiled teeth 07 and the inlaid teeth 08 maintain an embedded and fitted relationship.

[0040] In this embodiment, the high rock-breaking efficiency of PDC profiled teeth 07 in medium-hard and lower formations is fully utilized to ensure a high drilling rate in the early stages of drilling. When PDC profiled teeth 07 wear out, they are replaced by wear-resistant impregnated teeth 08 to ensure longevity in extremely hard and highly abrasive formations. This embodiment achieves a "efficiency first, durability second" sequential operating mode through a two-stage arrangement (PDC profiled teeth 07 followed by impregnated teeth 08).

[0041] In another optional embodiment, the cutting teeth used in the first cutting unit and the cutting teeth used in the second cutting unit are both alternately arranged with PDC special-shaped teeth 07 and impregnated teeth 08. Furthermore, along the drilling direction, behind each PDC profile tooth 07 in the first cutting unit is a corresponding impregnated tooth 08 in the second cutting unit, and behind each impregnated tooth 08 in the first cutting unit is a corresponding PDC profile tooth 07 in the second cutting unit.

[0042] Based on the aforementioned first and second cutting units, the following specific provisions are made: both the first and second cutting units are composed of alternating PDC profiled teeth 07 and impregnated teeth 08.

[0043] Along the drilling direction, directly behind each PDC profile tooth 07 in the first cutting unit, there is a corresponding impregnated tooth 08 in the second cutting unit; conversely, directly behind each impregnated tooth 08 in the first cutting unit, there is a corresponding PDC profile tooth 07 in the second cutting unit.

[0044] This arrangement ensures that at any given time, both PDC profiled teeth 07 and impregnated teeth 08 are simultaneously breaking rock on the working surface, guaranteeing overall performance. When a certain type of cutting tooth in the first cutting unit wears out, different types of cutting teeth in the second cutting unit immediately take over at the same position, achieving a smooth transition and continuous balance of performance.

[0045] This arrangement ensures that the drill bit possesses both the cutting efficiency of the PDC profiled teeth 07 and the wear resistance of the impregnated teeth 08 throughout its entire lifespan (early and late stages). This avoids the problem of a sharp drop in drill bit performance caused by the failure of a single type of tooth.

[0046] In another optional embodiment, the first cutting unit uses PDC profiled teeth 07 and impregnated teeth 08 arranged in an alternating pattern, and the second cutting unit uses impregnated teeth 08 as the cutting teeth.

[0047] Based on the aforementioned first and second cutting units, the following specific limitations are made: the first cutting unit consists of PDC special-shaped teeth 07 and impregnated teeth 08 arranged alternately; the second cutting unit consists entirely of impregnated teeth 08.

[0048] This arrangement, during the early stages of drilling, utilizes a mix of PDC-shaped teeth 07 and impregnated teeth 08 in the first cutting unit to achieve both a certain drilling speed and impact resistance, adapting to formations with alternating soft and hard surfaces. Once the first cutting unit is completely worn out after entering purely hard formations, the impregnated teeth 08 in the fully wear-resistant second cutting unit take over subsequent rock breaking, extending working life. This method is suitable for drilling conditions where the upper formation is complex and the lower formation is homogeneous and extremely hard.

[0049] In this optional embodiment, the difference between the cutting edge height of the PDC profile tooth 07 and the cutting edge height of the impregnated tooth 08 is 0.8-1.2 mm.

[0050] In the first cutting unit, there is a 0.8-1.2mm difference in cutting edge height between adjacent PDC profiled teeth 07 and impregnated teeth 08. Depending on the design, either PDC profiled teeth 07 or impregnated teeth 08 can be higher.

[0051] Specifically, if the formation has good drillability, the PDC special-shaped tooth 07 can be 0.8-1.2 mm higher than the impregnated tooth 08; if the formation is a hard interlayer with poor drillability, the impregnated tooth 08 can be 0.8-1.2 mm higher than the PDC special-shaped tooth 07.

[0052] In this embodiment, when the PDC profile tooth 07 protrudes, its cutting efficiency is prioritized; when the impregnated tooth 08 protrudes, its stronger impact resistance is utilized to break through the hard layer, protecting the PDC profile tooth 07 from impact. This allows the cutting element, which is more suitable for the current formation characteristics, to undertake more rock-breaking work, thereby achieving the goal of protecting the fragile element and optimizing overall performance.

[0053] Please continue reading. Figure 5 In an optional embodiment, the PDC profile tooth 07 includes a 7D tooth 09, which includes three first inclined surfaces 10, three wide facets 11, and a central plane 12. The angle between each first inclined plane 10 and the central plane 12 is 12-15 degrees; The angle between each wide facet 11 and the central plane 12 is 5-8 degrees; The width of each wide facet 11 is 1.5-3mm.

[0054] This embodiment is a specific description of any of the aforementioned embodiments using the PDC profiled tooth 07. Specifically, it describes the geometry of the 7D tooth 09: it consists of three first inclined surfaces 10, three wide facets 11, and one central plane 12. The first inclined surfaces 10 (12-15°) primarily guide the lateral flow of rock cuttings, facilitating chip removal and preventing mud buildup. The wide facets 11 (5-8°) and the relatively wide edges (1.5-3mm) significantly increase the support strength and impact resistance of the cutting edge, preventing chipping.

[0055] The 7D tooth 09 integrates three major functions—facilitating chip removal, strong impact resistance, and high wear resistance—through a polyhedral design and localized reinforcement, thus solving the damage mechanism (impact, wear, and thermal damage) of highly abrasive formations to the PDC profile tooth 07.

[0056] Furthermore, the end face of the 7D tooth 09 has three symmetrical teardrop-shaped thickened diamond layers 13, one of which is aligned with the normal line of the 7D tooth 09, ensuring that the teardrop-shaped thickened diamond layer 13 is in the working area. This locally increases the thickness of the diamond layer in the working area, directly extending the wear resistance life of this critical area.

[0057] The normal line is a straight line perpendicular to the theoretical profile of the drill bit crown at the location of the tooth, representing the tooth's primary cutting direction or force direction.

[0058] Please continue reading. Figure 6 Unlike the aforementioned 7D tooth 09, in an optional embodiment, the PDC profile tooth 07 includes an arc ridge tooth 14, which includes an arc surface 15 and two second inclined surfaces 16. The radius of the arc surface 15 is 50-70mm, and the narrowest width is 1.5-3mm; The included angle between the two second inclined planes 16 is 135-155 degrees.

[0059] The geometry of the arc ridge tooth 14 includes a large radius (50-70mm) arc surface 15 forming the main cutting edge, and two second inclined surfaces 16 forming the ridge. The arc ridge tooth 14 is provided with welding mark grooves 17.

[0060] Among them, the large radius arc surface 15 changes the contact between the cutting edge and the rock from "line contact" to "surface contact", which greatly disperses the impact stress; the second inclined surface 16 (135-155°) in the shape of a roof is used to form an effective chip removal channel; the welding mark groove 17 ensures that when the arc ridge tooth 14 is brazed to the blade 02, its strongest working edge direction is accurately aligned with the rock breaking direction, ensuring performance.

[0061] The Arc Ridge Tooth 14 sacrifices a little sharpness through its unique arc-shaped 15-blade design, but gains significantly improved impact resistance and stability under large impact loads. It is suitable for formations containing hard nodules or severe soft-hard interlayers.

[0062] In an optional embodiment, the cone apex half angle β of the inner cone structure 05 is 30-45 degrees.

[0063] In this embodiment, the cone apex half angle β specifically refers to the acute angle between the cone generatrix (side line) and the cone central axis on the cone axis section (i.e., the section passing through the cone central axis) of the cone internal cone structure 05.

[0064] An angle of 30-45 degrees can maximize the area of ​​tooth placement on the core cone surface while ensuring structural strength.

[0065] The cone structure 05 inside the cone has teeth on its cone surface, which can break the rock in the center during drilling, thus solving the traditional problem of core drilling.

[0066] In an optional embodiment, the size of the cutting teeth in the second cutting unit is smaller than the size of the cutting teeth in the first cutting unit.

[0067] In this embodiment, each cutting tooth in the second cutting unit has a smaller size (diameter or cross-sectional area) than the cutting tooth in the corresponding first cutting unit. For example, the size ratio of the cutting teeth in the first cutting unit to the cutting teeth in the second cutting unit is 16:13.

[0068] Since the cutting teeth of the second cutting unit are embedded behind the first cutting unit, their installation space is limited by the cutting tooth base of the first cutting unit. Reducing the size of the cutting teeth of the second cutting unit can ensure that they can be reasonably arranged and form an effective figure-eight fit with the cutting teeth in the first cutting unit.

[0069] In an optional embodiment, the triangular polycrystalline balas has a tooth density of 1-3 grains / carat and is arranged in a three-level concentric ridge inlay pattern.

[0070] In this embodiment, the triangular polycrystalline balas set on the conical surface of the cone body has a tooth density of 1-3 grains / carat and is arranged in a three-level concentric ridge setting method.

[0071] Triangular polycrystalline Balas with a density of 1-3 grains / carat is selected. It has the advantages of larger grains and stronger aggression, which can reduce the difficulty of breaking the core rock (due to high confining pressure) and improve the core rock breaking efficiency.

[0072] The three-level concentric ridge setting method means that the triangular polycrystalline ballast is set in the pre-processed annular ridge groove, so that it is surrounded by the matrix material from all sides, with extremely strong bonding and preventing it from falling off.

[0073] In another alternative embodiment, the synthetic diamond particles used for pressing the impregnated teeth are selected with a particle size specifically chosen based on the abrasiveness of the target formation. The diamond particle size is measured in "mesh," and specific selectable ranges include different grades such as 25 / 35 mesh, 30 / 40 mesh, 40 / 50 mesh, and 50 / 60 mesh.

[0074] Diamond particles of a selected size are uniformly mixed with matrix powder (such as tungsten carbide-based powder) according to a specific formula, and then formed into impregnated tooth 08 blocks through powder metallurgy processes (such as hot pressing sintering), and finally brazed or sintered to the designated position of drill bit blade 02.

[0075] In this embodiment, for highly abrasive formations (such as quartz sandstone), diamonds with smaller particles such as 40 / 50 mesh or 50 / 60 mesh are preferred; for softer or less abrasive formations, diamonds with larger particles such as 25 / 35 mesh or 30 / 40 mesh are preferred; for formations with alternating soft and hard surfaces, two or more diamonds of different particle sizes can be mixed in a predetermined ratio.

[0076] On the conical surface of the cone structure 05 within the cone, triangular polycrystalline balas and natural diamonds can be simultaneously inlaid. For example, triangular polycrystalline balas can be arranged in a ridge setting, while natural diamonds are inlaid between rings or in specific areas.

[0077] Furthermore, in order to resist the impact of complex strata and take into account cutting efficiency, the first cutting unit selects wedge-shaped impregnated teeth, while the second cutting unit selects crescent-shaped columnar impregnated teeth 08 to fit with the cutting teeth in the first cutting unit in order to ensure service life in the later stage.

Claims

1. A PDC impregnated bit for drilling hard formations of high abrasivity, characterized in that, The drill bit comprises a bit body and a plurality of blades. The plurality of blades are arranged on the crown of the bit body, and a flute is formed between two adjacent blades, and a fan-shaped water channel is arranged on the flute. A cutting area is arranged on the blade, and a first cutting unit and a second cutting unit are arranged on the cutting area in the forward and backward direction of drilling, the second cutting unit is embedded in the rear of the first cutting unit and connected with the first cutting unit, and the second cutting unit replaces the rock breaking when the first cutting unit is worn. A conical inner cone structure is arranged in the central area of the crown, an inner water channel is arranged on the conical inner cone structure, and a triangular polycrystal baras is inlaid on the conical surface of the conical inner cone structure. The cutting teeth of the first cutting unit are PDC special-shaped teeth, and the cutting teeth of the second cutting unit are impregnated teeth.

2. The PDC impregnated bit of claim 1, wherein, The cutting teeth of the first cutting unit and the cutting teeth of the second cutting unit are alternately arranged by PDC special-shaped teeth and impregnated teeth.

3. The PDC impregnated bit of claim 1, wherein, In the forward direction of drilling, the rear of each PDC special-shaped tooth in the first cutting unit corresponds to the arrangement of the impregnated tooth in the second cutting unit, and the rear of each impregnated tooth in the first cutting unit corresponds to the arrangement of the PDC special-shaped tooth in the second cutting unit. The cutting teeth of the first cutting unit are PDC special-shaped teeth and impregnated teeth arranged alternately, and the cutting teeth of the second cutting unit are impregnated teeth.

4. The PDC impregnated bit of claim 1 wherein, The difference between the height of the PDC special-shaped tooth and the height of the impregnated tooth is 0.8-1.2mm.

5. The PDC impregnated bit of claim 4 wherein, The PDC special-shaped tooth comprises a 7D tooth, and the 7D tooth comprises three first inclined surfaces, three wide edge surfaces and a central flat surface.

6. The PDC impregnated bit of any one of claims 2-5, wherein, The included angle between each first inclined surface and the central flat surface is 12-15 degrees. The included angle between each wide edge surface and the central flat surface is 5-8 degrees. The edge width of each wide edge surface is 1.5-3mm. The PDC special-shaped tooth comprises an arc ridge tooth, and the arc ridge tooth comprises an arc surface and two second inclined surfaces.

7. The PDC impregnated bit of any one of claims 2-5, wherein, The radius of the arc surface is 50-70mm, and the narrowest width is 1.5-3mm. The included angle between the two second inclined surfaces is 135-155 degrees. The half angle β of the conical top of the conical inner cone structure is 30-45 degrees.

8. The PDC impregnated bit of any one of claims 1-5, wherein, The size of the cutting tooth in the second cutting unit is smaller than the size of the cutting tooth in the first cutting unit.

9. The PDC impregnated bit of any one of claims 1-5, wherein, The setting density of the triangular polycrystal baras is 1-3 grains per carat, and a three-level concentric ridge inlay method is adopted for arrangement.

10. The PDC impregnated bit of any one of claims 1-5, wherein, ​

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