Concave double-stage double-speed drill bit

Abstract

A concave double-stage double-speed drill bit comprises a drill bit body, a fixed blade is arranged on the drill bit body, PDC teeth are arranged on the fixed blade, at least one disc cutter cutting structure and a disc cutter supporting seat are arranged on the drill bit body, disc cutter cutting teeth are arranged on the disc cutter cutting structure, and the core area of the drill bit body is concave inwards. A rotary blade is arranged in a concave area of the drill bit, PDC teeth are arranged on the rotary blade and the fixed blade in an echelon mode, the rotary blade is connected with the drill bit through a thrust bearing, and a screw drill is arranged in a central flow channel of the drill bit and connected with the rotary blade. Protruding rock ridges can be formed at the center of the drill bit, the protruding rock ridges have the righting effect on the drill bit, impact failure of cutting teeth of the drill bit can be reduced, meanwhile, stress release of the protruding rock ridges and rock crushing difficulty are reduced, sliding friction is replaced with rolling friction, rotating resistance of rotating blades is reduced, the energy utilization rate of the drill bit is improved, and crossed scraping and cutting of the well bottom can be formed. The rock breaking efficiency of the drill is improved.

Description

Technical Field

[0001] The present invention belongs to the technical equipment fields of oil and gas drilling engineering, mine engineering, construction foundation engineering construction, geological drilling, tunnel engineering hydrology and trenchless technology, etc., and particularly relates to an in-concave type double-stage and double-speed drill bit. Background Art

[0002] A drill bit is a rock-breaking tool used to break rocks and form a wellbore in drilling engineering. Commonly used drill bits include PDC drill bits, roller cone drill bits and impact-rotation drill bits. A PDC drill bit relies on polycrystalline diamond compact (PDC) with high hardness, wear resistance and self-sharpening ability to shear and break rocks. Due to its high mechanical drilling rate, long service life and low drilling cost in soft to medium-hard formations, the PDC drill bit is widely used in drilling engineering. Existing fixed cutter teeth drill bits represented by PDC drill bits usually have several blades, and a plurality of cutting elements are arranged along the radial direction of the blade (for a PDC drill bit, the cutting elements are mainly polycrystalline diamond compacts, referred to as compacts or PDC teeth). However, when encountering hard formations, the cutting teeth on the nose and shoulder of the PDC drill bit are difficult to effectively penetrate into the formation, thus greatly reducing the mechanical drilling rate. A roller cone drill bit breaks rocks in an impact-crushing manner, forming deeper crushing tooth pits at the bottom of the well. When the formation is hard, it cannot cause volume rock breaking of the rock, thereby reducing the energy utilization rate and having a low rock-breaking efficiency. An impact-rotation drill bit is a fixed tooth rock-breaking tool used in conjunction with a down-the-hole hammer in impact-rotation drilling. The rock-breaking mechanism of the impact-rotation drill bit is significantly different from both the crushing mechanism of the roller cone drill bit and the cutting mechanism of the PDC drill bit. The impact-rotation drill bit relies on the instantaneous impact force of the teeth to break the bottom-hole rocks. The upper end of the impact-rotation drill bit is connected to a down-the-hole hammer. During operation, its hammer reciprocates under the action of the circulating fluid, repeatedly hitting the drill bit and providing an impact load to the teeth. Usually, when the impact-rotation drill bit drills in brittle formations, especially hard formations, a relatively high rock-breaking efficiency can be achieved.

[0003] In addition, during the design process of a PDC bit, a plane passing through the central axis of the bit is usually arbitrarily determined as the tooth-arrangement axial plane (also simply referred to as the axial plane), and the radial and axial positions of each cutting tooth on the bit can be accurately represented on this axial plane. When the bit rotates around its own axis under the condition of unchanged axial position, the intersection line formed by the cutting-edge contour line of the cutting tooth and the axial plane is the axial-plane contour line of the cutting tooth. Then, by gathering the axial-plane contour lines of all the main cutting teeth (or all the main cutting teeth on several specified blades) on the bit in this axial plane, the axial-plane tooth-arrangement diagram of the bit (or the axial-plane tooth-arrangement diagram of several specified blades) is formed. Because the axial-plane tooth-arrangement diagram can accurately reflect the radial coverage of the cutting teeth on the bit over the bottom-hole rock, it is also called the bottom-hole coverage tooth-arrangement diagram, simply referred to as the coverage tooth-arrangement diagram or the bottom-hole coverage diagram. In the bottom-hole coverage diagram of the bit, an outer envelope curve tangent to the axial-plane contour lines of all the main cutting teeth is the cutting contour line of the bit (i.e., the crown contour line of the bit). Additionally, if only the cutting teeth on a certain specified blade are shown and the cutting teeth on other blades are hidden, the axial-plane tooth-arrangement diagram of this blade is formed. In the axial-plane tooth-arrangement diagram of the blade, an outer envelope curve tangent to the axial-plane contour lines of each main cutting tooth is called the cutting contour line of this blade. If the bit rotates around its own axis under the condition of unchanged axial position, for a certain blade body, the intersection line between its front side and the tooth-arrangement surface will sweep to form a revolution surface with the central axis of the bit as the axis as the bit rotates, and the intersection line between this revolution surface and the axial plane is the body contour line of the blade, that is, the blade contour line. Usually, since the exposed heights of the main cutting teeth arranged on the tooth-arrangement surface of the blade are the same or similar (except for the area near the gauge diameter surface), the shapes of the cutting contour line and the body contour line of the blade are basically parallel, and there may be obvious differences only in the area near the gauge diameter. Therefore, usually, if the cutting contour lines of different blades are to be matched and adapted to each other, different blade contour lines need to be designed to be completely or basically the same shape, and then, together with the tooth-arrangement method with the same or similar exposed heights, it can be achieved.

[0004] In the Chinese patent "A Static and Dynamic Dual-Stage PDC Bit" (Patent No.: 201710044703.8) submitted by Sichuan Wanji Diamond Bit Co., Ltd., the bit includes a bit body and fixed cutter wings. PDC teeth, water holes or nozzles, etc. are provided on the fixed cutter wings. A rotating cutter wing is provided in the central region of the bit. PDC teeth are provided on the rotating cutter wing, and the PDC teeth of the rotating cutter wing and the fixed cutter wing are arranged in a stepped manner. Such a structure can improve the rock-breaking efficiency of the PDC teeth in the central region of the bit, increase the mechanical drilling rate of the bit. At the same time, relying on the characteristics of the dual-stage bit, it enhances the drilling stability of the bit and prolongs the service life of the bit, thereby improving the comprehensive performance of the bit. However, in this bit, the rotation of the rotating cutter wing and the bit body is a sliding friction, and its frictional resistance is relatively large. Moreover, the cutting teeth of the fixed cutter wings on the outside of the bit are limited, and the service life of the bit cannot be guaranteed. In order to overcome the above defects, an inner concave dual-stage dual-speed bit is proposed. Summary of the Invention

[0005] The purpose is to propose an inner concave dual-stage dual-speed bit. The rotating cutter wing in the central part of the bit is driven by a positive displacement motor, and the fixed cutter wings are driven by the drill pipe, realizing two kinds of cutting structures and two speeds for rock breaking inside and outside the bit. At the same time, the inner concave rotating cutter wing of the bit forms a raised rock ridge at the bottom of the well, which can improve the drilling stability of the bit. At the same time, the stress around the raised rock ridge is released, reducing the difficulty of rock breaking. At the same time, a thrust bearing is provided at the bottom of the rotating cutter wing, replacing sliding friction with rolling friction, reducing the frictional resistance of the rotating cutter wing, and improving the energy utilization rate of the bit. The disc cutter cutting structure and the fixed cutting structure form cross scraping in the outer area of the bit, which can improve the rock-breaking efficiency of the bit. At the same time, the alternating work of the disc cutter cutting structure can reduce the wear speed of the cutting teeth, thereby prolonging the service life of the bit.

[0006] In order to achieve the above purpose, the present utility model adopts the following technologies:

[0007] An inner concave dual-stage dual-speed bit, including a bit body, on which fixed cutter wings are provided, PDC teeth are provided on the fixed cutter wings, a central flow channel and nozzles are provided on the bit body; characterized in that: at least one disc cutter cutting structure and a disc cutter support seat are provided on the bit body, disc cutter cutting teeth are provided on the disc cutter cutting structure, the central region of the bit body is recessed inward, a rotating cutter wing is provided in the inner concave area of the bit, fixed cutting teeth are provided on the rotating cutter wing, the PDC teeth of the rotating cutter wing and the fixed cutter wing are arranged in a stepped manner to form a dual-stage cutting structure, the rotating cutter wing is connected to the bit through a thrust bearing, a positive displacement motor is provided in the central flow channel of the bit, and the positive displacement motor is connected to the rotating cutter wing.

[0008] In the above solution, a concave double-stage and double-speed drill bit includes a drill bit body, a fixed cutter wing is arranged on the drill bit body, PDC teeth are arranged on the fixed cutter wing, a central flow channel and nozzles are arranged on the drill bit body; its characteristics are as follows: at least one disc cutter cutting structure and a disc cutter support seat are arranged on the drill bit body, disc cutter cutting teeth are arranged on the disc cutter cutting structure, the central area of the drill bit body is recessed inward, a rotating cutter wing is arranged in the recessed area of the drill bit, fixed cutting teeth are arranged on the rotating cutter wing, the rotating cutter wing and the fixed cutter wing are arranged with PDC teeth in a stepped manner to form a double-stage cutting structure, the rotating cutter wing is connected to the drill bit through a thrust bearing, a positive displacement motor is arranged in the central flow channel of the drill bit body, and the positive displacement motor is connected to the rotating cutter wing. The drilling fluid in the central flow channel of the drill bit body drives the positive displacement motor of the drill bit body to rotate, and the positive displacement motor is connected to the rotating cutter wing. In this way, the positive displacement motor gives the rotating cutter wing an independent rotational speed, and the top drive gives the fixed cutter wing a rotational speed through the drill pipe. In this way, the two areas inside and outside the drill bit obtain two independent rotational speeds, and the two rotational speeds inside and outside can be reasonably allocated according to different drilling conditions and formation conditions. The central area of the drill bit is recessed inward, and the rotating cutter wing and the fixed cutter wing are arranged with PDC teeth in a stepped manner. In this way, a raised rock ridge will be formed in the central part of the drill bit. The raised rock ridge has a straightening effect on the drill bit, which can reduce the impact failure of the cutting teeth of the drill bit. At the same time, the stress of the raised rock ridge is released, its rock strength will be reduced, and the rock breaking difficulty will be reduced; the rotating cutter wing is connected to the drill bit body through a thrust bearing. Since the rotating cutter wing is equivalent to the drill bit body to rotate, rolling friction is used instead of sliding friction, reducing the rotational resistance of the rotating cutter wing and improving the energy utilization rate of the drill bit; a disc cutter cutting structure and a disc cutter support seat are arranged on the drill bit body, and the disc cutter cutting structure rotates around the disc cutter support seat. In this way, the disc cutter cutting teeth will alternately scrape the rock. The external area of the drill bit acts together with the PDC teeth on the fixed cutter wing and the disc cutter cutting teeth to form cross-scraping of the bottom hole, improving the rock-breaking efficiency of the drill bit. The alternating work of the disc cutter cutting teeth can reduce the wear speed of the cutting teeth, thereby prolonging the service life of the drill bit.

[0009] As an option, at least one horizontal nozzle is arranged on the side of the fixed cutter wing in the recessed area of the drill bit body.

[0010] In the above solution, at least one horizontal nozzle is arranged in the recessed area of the drill bit body. Since a rotating cutter wing is arranged in the recessed area of the heart part, it is not easy to directly arrange a nozzle in this area. A horizontal nozzle can be arranged on the side of the fixed cutter wing. The horizontal nozzle can cool the cutting teeth on the rotating cutter wing and can also carry the cuttings cut by the rotating cutter wing away from the bottom of the well, preventing the occurrence of repeated cutting and mud packing of the drill bit.

[0011] As an option, at least one inner gauge cutting tooth is arranged on the side of the fixed cutter wing in the recessed area of the drill bit body.

[0012] In the above solution, at least one internal gauge cutting tooth is provided on the side of the fixed cutter wing in the concave area of the drill bit body. Since a raised rock ridge will be formed in the center of the drill bit, the tooth that cuts the rock ridge is called the internal gauge tooth. This tooth has a large load during operation and is prone to failure. By providing at least one internal gauge cutting tooth on the side of the fixed cutter wing, the service life of the internal gauge tooth can be extended, and the formation of the rock ridge can also be ensured.

[0013] As an option, at least two disc cutter cutting structures are provided on the drill bit body, and the two disc cutter cutting structures are located at different radial positions of the drill bit.

[0014] In the above solution, at least two disc cutter cutting structures are provided on the drill bit body, and the two disc cutter cutting structures are located at different radial positions of the drill bit, which can broaden the range of the disc cutter cutting structure in the radial area of the drill bit, thereby increasing the cross-cutting area of the drill bit and improving the drilling efficiency of the drill bit.

[0015] As an option, at least one disc cutter cutting structure is provided on the drill bit body, and the disc cutter cutting teeth on the disc cutter cutting structure are cut into internal gauge cutting teeth.

[0016] In the above solution, at least one disc cutter cutting structure is provided on the drill bit body, and the disc cutter cutting teeth on the disc cutter cutting structure are internal gauge cutting teeth. Using the disc cutter cutting teeth to replace the PDC teeth on the fixed cutter wing as the internal gauge cutting teeth facilitates the installation of the rotating cutter wing, reduces the installation difficulty of the rotating cutter wing, and at the same time, the disc cutter cutting teeth work alternately, which can maximize the service life of the internal gauge teeth.

[0017] Beneficial effects:

[0018] 1. The drilling fluid in the central flow channel of the drill bit body drives the positive displacement motor of the drill bit body to rotate. The positive displacement motor is connected to the rotating cutter wing. In this way, the positive displacement motor gives an independent rotational speed to the rotating cutter wing, and the top drive gives a rotational speed to the fixed cutter wing through the drill pipe. In this way, two independent rotational speeds are obtained in the inner and outer regions of the drill bit, and the two rotational speeds inside and outside can be reasonably allocated according to different drilling conditions and formation conditions.

[0019] 2. The area in the center of the drill bit is concave, and the rotating cutter wing and the fixed cutter wing are arranged with PDC teeth in a stepped manner. In this way, a raised rock ridge will be formed in the center of the drill bit. The raised rock ridge has a straightening effect on the drill bit, which can reduce the impact failure of the cutting teeth of the drill bit. At the same time, with the stress release of the raised rock ridge, the rock strength will be reduced, and the difficulty of rock fragmentation will be reduced.

[0020] 3. The rotating cutter wing is connected to the drill bit body through a thrust bearing. Since the rotating cutter wing is equivalent to the drill bit body rotating, rolling friction is used instead of sliding friction, reducing the rotational resistance of the rotating cutter wing and improving the energy utilization rate of the drill bit.

[0021] 4. The drill bit body is provided with a disc cutter cutting structure and a disc cutter support seat. The disc cutter cutting structure rotates around the disc cutter support seat, so that the disc cutter cutting teeth will alternately scrape the rock. The external area of the drill bit forms a cross-scraping of the bottom hole through the combined action of the PDC teeth on the fixed cutter wings and the disc cutter cutting teeth, improving the rock-breaking efficiency of the drill bit. The alternating operation of the disc cutter cutting teeth can reduce the wear speed of the cutting teeth, thereby prolonging the service life of the drill bit. Brief Description of the Drawings

[0022] Figure 1 is a cross-sectional view of an inwardly concave double-stage double-speed drill bit;

[0023] Figure 2 is a three-dimensional schematic diagram of an inwardly concave double-stage double-speed drill bit;

[0024] Figure 3 is a top view of an inwardly concave double-stage double-speed drill bit;

[0025] Figure 4 is an assembly diagram of an inwardly concave double-stage double-speed drill bit;

[0026] Figure 5 is a three-dimensional diagram of a rotating cutter wing;

[0027] Figure 6 is a radial coverage diagram of the drill bit;

[0028] Figure 7 is a radial coverage diagram of the drill bit provided with internal gauge teeth;

[0029] Figure 8 is a radial coverage diagram of the drill bit at different radial positions of the disc cutter cutting structure

[0030] Reference Signs in the Drawings:

[0031] 1 - Drill bit body; 12 - Drill bit central flow channel; 2 - Fixed cutter wing; 21 - PDC tooth; 22 - Internal gauge cutting tooth; 3 - Disc cutter cutting structure; 31 - Disc cutter cutting tooth; 32 - Disc cutter support seat; 4 - Rotating cutter wing; 41 - Fixed cutting tooth of rotating cutter wing; 42 - Ball groove; 5 - Thrust bearing; 6 - Bottom hole rock; 7 - Positive displacement motor; 8 - Nozzle; 82 - Horizontal nozzle; A - Drill bit body contour line; B - Drill bit cutting contour line. Detailed Embodiments

[0032] The following non-limiting embodiments are used to illustrate the present invention:

[0033] An inwardly concave double-stage and double-speed drill bit includes a drill bit body, on which fixed cutter wings are provided, PDC teeth are provided on the fixed cutter wings, a central flow channel and nozzles are provided on the drill bit body; it is characterized in that: at least one disc cutter cutting structure and a disc cutter support seat are provided on the drill bit body, disc cutter cutting teeth are provided on the disc cutter cutting structure, the central region of the drill bit body is recessed inward, a rotating cutter wing is provided in the recessed area of the drill bit, fixed cutting teeth are provided on the rotating cutter wing, the rotating cutter wing and the fixed cutter wing are arranged in a stepped manner with PDC teeth to form a double-stage cutting structure, the rotating cutter wing is connected to the drill bit through a thrust bearing, a positive displacement motor is provided in the central flow channel of the drill bit, and the positive displacement motor is connected to the rotating cutter wing. The drilling fluid in the central flow channel of the drill bit body drives the positive displacement motor of the drill bit body to rotate, and the positive displacement motor is connected to the rotating cutter wing, so that the positive displacement motor gives the rotating cutter wing an independent rotational speed, and the top drive gives the fixed cutter wing a rotational speed through the drill pipe. In this way, two independent rotational speeds are obtained in the inner and outer regions of the drill bit, and the two rotational speeds inside and outside can be reasonably allocated according to different drilling conditions and formation conditions. The central region of the drill bit is recessed inward, and the rotating cutter wing and the fixed cutter wing are arranged in a stepped manner with PDC teeth. In this way, a raised rock ridge will be formed in the center of the drill bit. The raised rock ridge has a straightening effect on the drill bit, which can reduce the impact failure of the cutting teeth of the drill bit. At the same time, with the stress release of the raised rock ridge, the rock strength will be reduced and the rock breaking difficulty will be reduced; the rotating cutter wing is connected to the drill bit body through a thrust bearing. Since the rotating cutter wing is equivalent to the drill bit body rotating, rolling friction is used instead of sliding friction, reducing the rotational resistance of the rotating cutter wing and improving the energy utilization rate of the drill bit; a disc cutter cutting structure and a disc cutter support seat are provided on the drill bit body, and the disc cutter cutting structure rotates around the disc cutter support seat. In this way, the disc cutter cutting teeth will alternately scrape the rock. The outer region of the drill bit acts together with the PDC teeth on the fixed cutter wing and the disc cutter cutting teeth to form cross-scraping of the bottom hole, improving the rock-breaking efficiency of the drill bit. The alternating operation of the disc cutter cutting teeth can reduce the wear speed of the cutting teeth, thereby extending the service life of the drill bit. As shown in Figure 1 、 2 Figures 3, 4, 5, and 6.

[0034] Preferably, at least one horizontal nozzle is provided in the recessed area of the drill bit body. Since a rotating cutter wing is provided in the recessed area of the center, it is not easy to directly set a nozzle in this area. A horizontal nozzle can be set on the side of the fixed cutter wing. The horizontal nozzle can cool the cutting teeth on the rotating cutter wing and can also carry the cuttings cut by the rotating cutter wing away from the bottom of the well, preventing the occurrence of repeated cutting and mud packing of the drill bit, as shown in Figure 1 Figure

[0035] Preferably, at least one inner gauge cutting tooth is provided on the side of the fixed cutter wing in the recessed area of the drill bit body. Since a raised rock ridge will be formed in the center of the drill bit, the tooth that cuts to form the rock ridge is called the inner gauge tooth. This tooth has a large load during operation and is prone to failure. At least one inner gauge cutting tooth is provided on the side of the fixed cutter wing, which can extend the service life of the inner gauge tooth and can also ensure the formation of the rock ridge.Figure 7 as shown

[0036] Preferably, at least two disc cutter cutting structures are provided on the drill bit body, and the two disc cutter cutting structures are located at different radial positions of the drill bit, which can broaden the range of the disc cutter cutting structure in the radial area of the drill bit, thereby increasing the area of cross scraping of the drill bit and improving the drilling efficiency of the drill bit, as Figure 8 shown

[0037] Preferably, at least one disc cutter cutting structure is provided on the drill bit body, and the disc cutter cutting teeth on the disc cutter cutting structure are inner diameter protecting cutting teeth. The disc cutter cutting teeth are used to replace the PDC teeth on the fixed cutter wing as the inner diameter protecting cutting teeth, which facilitates the installation of the rotating cutter wing and reduces the installation difficulty of the rotating cutter wing. At the same time, the disc cutter cutting teeth work alternately, which can maximize the service life of the inner diameter protecting teeth, as Figure 8 shown

[0038] As mentioned above, it is not a restriction on the present utility model in any form. Although the present utility model has been disclosed through the above embodiments, it is not intended to limit the present utility model. Any person skilled in the art, without departing from the scope of the technical solution of the present utility model, can make some changes or modifications to the above-disclosed technical content to form equivalent embodiments with equivalent changes. However, as long as it does not depart from the content of the technical solution of the present utility model, any simple modification, equivalent change and modification made to the above embodiments based on the technical essence of the present utility model still fall within the scope of the technical solution of the present utility model.

Claims

1. An inwardly concave type double-stage and double-speed drill bit, comprising a drill bit body, a fixed cutter blade is arranged on the drill bit body, PDC teeth are arranged on the fixed cutter blade, a central flow channel and a nozzle are arranged on the drill bit body; it is characterized in that: At least one disc cutter cutting structure and a disc cutter support seat are provided on the drill bit body. Disc cutter cutting teeth are provided on the disc cutter cutting structure. The central region of the drill bit body is recessed inward. Rotary cutter wings are provided in the recessed area of the drill bit. Fixed cutting teeth are provided on the rotary cutter wings. The rotary cutter wings and the fixed cutter wings are arranged with PDC teeth in a stepped manner to form a two-stage cutting structure. The rotary cutter wings are connected to the drill bit through thrust bearings. A positive displacement motor is provided in the central flow channel of the drill bit, and the positive displacement motor is connected to the rotary cutter wings.

2. The concave double-stage and double-speed drill bit according to claim 1, characterized in that: At least one horizontal nozzle is provided on the side of the fixed cutter wing in the recessed area of the drill bit body.

3. The concave double-stage and double-speed drill bit according to claim 1, wherein: At least one inner gauge cutting tooth is provided on the side of the fixed cutter wing in the recessed area of the drill bit body.

4. The concave double-stage and double-speed drill bit according to claim 1, wherein: At least two disc cutter cutting structures are provided on the drill bit body, and the two disc cutter cutting structures are located at different radial positions of the drill bit.

5. The concave double-stage and double-speed drill bit according to claim 1, wherein: At least one disc cutter cutting structure is provided on the drill bit body, and the disc cutter cutting teeth on the disc cutter cutting structure are inner gauge cutting teeth.

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