PDC (Polycrystalline Diamond Compact) drill bit with damping teeth

Abstract

The invention discloses a PDC drill bit with damping teeth. The drill bit comprises a drill bit body, a plurality of blades extending to the drill bit body and water holes formed in the drill bit body, and damping PDC modules are arranged on the blades; the damping PDC module is composed of damping PDC teeth, bushings, elastic elements and limiters, each damping PDC tooth comprises a polycrystalline diamond layer, a first supporting base body and a second supporting base body, and the axis of the first supporting base body and the axis of the second supporting base body are in an L shape; when the damping PDC teeth bear an overlarge axial load, the elastic element is compressed, and the scraping depth of the PDC teeth is reduced, and when the axial load is reduced, the elastic element is extended, and the scraping depth of the PDC teeth is increased. According to the drill bit, the scraping depth of the PDC teeth can be controlled, the characteristic that the PDC teeth are high in rock breaking efficiency in soft stratums is reserved, the phenomenon that the PDC teeth are clamped and slipped due to the fact that the PDC teeth drill too deep in stratums difficult to drill can be prevented, the rock breaking efficiency of the drill bit is improved, and the service life of the drill bit is prolonged.

Description

Technical Field

[0001] The invention belongs to the technical field of drilling equipment for petroleum and natural gas, mining engineering, building foundation engineering construction, geology, hydrology and the like, and particularly relates to a shock-absorbing tooth PDC drill bit. Background Art

[0002] The drill bit is a rock-breaking tool used to break rocks and form wellbores in drilling projects. Commonly used ones include polycrystalline diamond composite drill bits (PDC drill bits), roller bits, and impregnated diamond drill bits. PDC drill bits rely on polycrystalline diamond composites with high hardness, high wear resistance, and self-sharpening ability to shear rocks. PDC drill bits have been widely used in oil and gas exploration, geothermal drilling operations and other projects due to their advantages of high mechanical penetration rate, long service life, and low drilling cost in soft to medium-hard formations. Fixed cutting tooth drill bits represented by PDC drill bits usually have several blades, and multiple cutting elements are arranged on the blades along the radial direction of the drill bit (for PDC drill bits, the cutting elements are mainly polycrystalline diamond composites, referred to as composites or PDC teeth).

[0003] During the drilling process, the composite cutting teeth of the PDC drill bit overcome the formation stress and drill forward under the action of drilling pressure and torque. The PDC drill bit breaks the rock in a shearing manner. Compared with the rock breaking method of the roller bit by impact crushing, the required driving torque is larger. In the ideal drilling process, under a certain drilling pressure, the PDC drill bit evenly eats into the formation at a constant depth, produces uniform scraping and cutting of the rock, and its torque feedback tends to be stable. However, due to the complexity of the formation conditions downhole, especially when drilling in soft and hard formations, the depth of the drill bit entering the formation changes frequently, and the vibration degree of the drill bit torque feedback becomes more intense. In severe cases, the drill bit enters the formation too deep, which will cause the driving torque to fail to drive the drill bit to rotate and cause the drill bit to stop. At this time, the drill string continues to twist under the drive of the turntable. When the energy accumulated in the drill string is sufficient to overcome the torque of the interaction between the drill bit and the formation, the drill bit transitions from a static state to a moving state, the energy accumulated in the drill string is released instantly, and the drill bit suddenly accelerates several times faster than the normal speed. This is the stick-slip phenomenon of the drill bit. This phenomenon can easily cause the drill bit and drill tools to rotate and twist at high speed, causing the drill bit cutting teeth to bear large circumferential impact loads, resulting in drill bit tooth collapse, damage, drill tool breakage, and damage to other downhole tools and measuring instruments, seriously affecting drilling efficiency. In addition, since the depth of the PDC drill bit into the formation is particularly sensitive to changes in drilling pressure, and the complexity of the interaction between the cutting teeth and the rock, the PDC drill bit also has longitudinal vibration along the axial direction of the drill bit, which will also affect the drill bit life and mechanical penetration rate.

[0004] The patent "A PDC cutting tooth based on a shock-absorbing structure" discloses a method for reducing the impact of PDC teeth of a PDC drill bit, but this technology has the following three problems. First, this technology uses conventional cylindrical PDC teeth, and the tooth holes where the PDC teeth are installed are opened on the side of the blade. Since the rake angles of each PDC tooth are different, the angle of the tool needs to be adjusted at any time when processing the tooth holes. At the same time, there are interferences between other blades and the processed tooth holes during the processing. That is to say, when the tool drills and mills the tooth holes from the side of the blade, it will damage the adjacent blades, affecting the integrity of the blade, and the damaged blades need to be repaired later. Second, when the rake angle of the PDC tooth is too small (such as the inner cone area), the axial telescopic range of the PDC tooth is limited, which leads to unclear adjustment of the PDC tooth penetration depth and weakened axial buffering effect.

[0005] Therefore, how to reduce the difficulty of processing the tooth holes of PDC drill bits, improve the manufacturing efficiency of drill bits, control the depth of the drill bit into the rock, reduce the sensitivity of the drill bit to drilling pressure, eliminate the drill bit sticking and jumping, and keep the drill bit torque in a relatively stable state of motion under a given drilling pressure, is an important technical problem to extend the service life of downhole drilling tools and drill bits and improve drilling efficiency. Summary of the invention

[0006] The purpose of the present invention is to provide a PDC drill bit in which the PDC teeth can be axially retracted during the drilling process, so as to control the change of the scraping depth of the PDC teeth in soft and hard interlaced formations and gravel-containing inhomogeneous formations, improve the impact resistance of the PDC teeth, thereby extending the life of the PDC teeth and reducing the frequency of drilling.

[0007] In order to achieve the above object, the present invention adopts the following technologies: A PDC drill bit with shock-absorbing teeth comprises a drill bit body, blades and PDC teeth arranged on the blades, the drill bit body is provided with water holes, at least one of the PDC teeth is a shock-absorbing PDC module, the shock-absorbing PDC module comprises a shock-absorbing PDC tooth, a bushing, an elastic element and a stopper, the shock-absorbing PDC tooth is composed of a polycrystalline diamond layer, a first supporting substrate and a second supporting substrate, the axes of the first supporting substrate and the second supporting substrate are L-shaped, an elastic element is provided between the shock-absorbing PDC tooth and the bushing to form a sliding connection, the stopper is provided between the bushing and the shock-absorbing PDC tooth, a tooth hole is opened on the blade, the axis of the tooth hole coincides with the normal line of the drill bit cutting profile, and the blade and the bushing are connected by welding or interference fit.

[0008] In the above scheme, when the drill bit is subjected to a smaller axial load, the elastic element is under a smaller compression; when the drill bit's penetration depth suddenly increases or encounters uneven formations, the drill bit's axial load increases, the elastic element is more compressed, and the shock-absorbing PDC teeth move repeatedly in this way, so that they have the ability to axially expand and contract, thereby achieving the purpose of buffering and shock reduction.

[0009] In the above scheme, the cutting profile (also called the crown profile) is one of the important structural features of the drill bit. It reflects the working position and state of each cutting element on the drill bit in crushing rocks at the bottom of the well. It is a structural feature that has an important influence on the formation adaptability and drilling performance of the drill bit. At present, the cutting profile of the diamond drill bit is parabolic, generally including five parts: inner cone, nose, outer cone, shoulder and gauge area. Assume that there is a cutting plane on the drill bit that passes through the axis of the drill bit and a certain point on the drill bit (called the axis plane or axial plane passing through the point). When the drill bit rotates around its own axis under the condition of zero drilling speed, the tooth edge contour line of the scraping tooth intersects with the cutting plane or the axial plane to form an intersection line, which is the axial surface contour line of the scraping tooth. The axial surface contour lines of all scraping teeth are brought together to form the bottom hole coverage map of the drill bit. The cutting profile of the drill bit refers to the envelope curve in which the axial surface contour lines of all teeth are tangent in the bottom hole coverage map. Such as Fig.12 This is the bottom hole coverage diagram of the shock-absorbing PDC tooth module in the drill bit axis plane.

[0010] As an option, the side wall of the bushing is provided with a limiting hole that cooperates with the limiter, and the second supporting base is provided with a limiting groove that cooperates with the limiter.

[0011] In the above scheme, the shock-absorbing PDC tooth can be prevented from falling out of the bushing, thereby preventing it from falling out, and the axial extension and contraction stroke of the shock-absorbing PDC tooth depends on the length of the limiting groove.

[0012] As an option, the axes of the first supporting base and the second supporting base are L-shaped, and the included angle α thereof is in the range of 90°<α<180°.

[0013] In the above scheme, within such an angle range, the PDC teeth can be directly and vertically installed in the cylindrical tooth socket, and different angles α can make the cutting teeth effectively contact the rock at different rake angles.

[0014] Alternatively, an elastic element is provided between the bushing and the shock-absorbing PDC tooth, and the elastic element is a spring.

[0015] In the above solution, the spring is stiffer and less prone to damage than other elastic elements such as rubber.

[0016] Alternatively, the polycrystalline diamond layer is in a plane shape, a roof shape, or a Mercedes-Benz shape.

[0017] In the above scheme, cutting teeth of different shapes match different strata, thereby broadening the application range of the drill bit.

[0018] Alternatively, the shock-absorbing PDC teeth are installed on a PDC-roller cone composite drill bit, a cross-scraping composite drill bit or an impact-scraping composite drill bit.

[0019] In the above scheme, different types of drill bits are matched with different strata, thereby broadening the application range of the drill bits.

[0020] The advantages of the present invention are: 1. The elastic element of the shock-absorbing PDC module can make the shock-absorbing PDC teeth axially expand and contract under the action of the change of axial load, so as to absorb part of the impact load and achieve the purpose of shock absorption, prolong the impact time, reduce the impact force, and improve the impact resistance of the PDC cutting teeth.

[0021] 2. The shock-absorbing PDC teeth have the ability of axial expansion and contraction to control their scraping depth in different formations. In soft formations, the axial force is small and the scraping depth is large, which improves drilling efficiency. In hard formations, the axial force is large and the scraping depth is small, which plays a role of self-protection to prevent drill sticking and extend the life of the drill bit.

[0022] 3. The shock-absorbing PDC tooth has a different appearance from the conventional PDC tooth. The axis of the first support base and the second support base is L-shaped, and the range of the angle α is 90°<α<180°. On the one hand, it can reduce the difficulty of processing the tooth hole of the PDC drill bit and improve the manufacturing efficiency of the drill bit. On the other hand, the cutting teeth with different angles α can obtain corresponding different rake angles, so there is no need to control the tooth socket to control the rake angle of the cutting teeth. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art.

[0024] Figure 1 A front view of a shock-absorbing PDC drill bit.

[0025] Figure 2 Schematic diagram of the shock-absorbing PDC flat teeth.

[0026] Figure 3 Schematic diagram of the shock-absorbing PDC module.

[0027] Figure 4 Schematic diagram of shock-absorbing PDC ridge teeth.

[0028] Figure 5 Schematic diagram of the shock-absorbing PDC ridge tooth module.

[0029] Figure 6 Schematic diagram of the shock-absorbing PDC Mercedes-Benz gear.

[0030] Figure 7 Schematic diagram of the shock-absorbing PDC Mercedes-Benz gear module.

[0031] Figure 8 Schematic diagram of the bushing.

[0032] Fig. 9 Schematic diagram of the overall structure of the shock-absorbing PDC tooth.

[0033] Fig.10 It is a schematic diagram of the shock-absorbing PDC teeth when cutting rock formations normally.

[0034] Fig.11 It is a schematic diagram of the shock-absorbing PDC tooth when it is impacted.

[0035] Fig.12 This is the bottom hole coverage diagram of the shock-absorbing PDC tooth module in the drill bit axis plane.

[0036] In the figure, 1- shock-absorbing PDC tooth; 11- polycrystalline diamond layer; 12- first supporting substrate; 13- second supporting substrate; 14- limiting groove; 15- second supporting substrate axis; 151- tooth hole axis; 16- first supporting substrate axis; 2- shock-absorbing PDC drill bit; 21- drill bit blade; 22- drill bit water hole, 23- shock-absorbing PDC drill bit rotation center line, 3- shock-absorbing PDC module, 4- elastic element, 5- bushing, 51- limiting hole, 6- limiter, 7- homogeneous rock formation, 71- inhomogeneous rock formation, 8- conventional PDC tooth, 9- drill bit cutting profile normal, 10- cutting profile. DETAILED DESCRIPTION

[0037] For this specific implementation mode, Figure 1 The shock-absorbing tooth PDC drill bit comprises a shock-absorbing PDC drill bit 2, on which a drill blade 21 and a drill water hole 22 are arranged; at least one shock-absorbing PDC module 3 is installed on the drill blade 21.

[0038] Fig. 9 The schematic diagram of the shock-absorbing PDC module 3 is shown. The shock-absorbing PDC module 3 includes a shock-absorbing PDC tooth 1, a bushing 5, an elastic element 4, and a stopper 6. The shock-absorbing PDC tooth 1 is composed of a polycrystalline diamond layer 11, a first support substrate 12, and a second support substrate 13. A limit groove 14 is arranged on the second support substrate 13. The axis 16 of the first support substrate and the axis 15 of the second support substrate are L-shaped, and the angle α is 90°-180°. Different angles α can make the cutting teeth effectively contact the rock at different rake angles. The second support substrate 13 is provided with a limit groove 14 that cooperates with the stopper 6, so that the shock-absorbing PDC tooth 1 cannot fall out of the bushing 5, and plays an anti-falling role. The axial extension and retraction stroke of the shock-absorbing PDC tooth depends on the length of the limit groove 14. An elastic element 4 is arranged between the bushing 5 and the shock-absorbing PDC tooth 1. The elastic element 4 is a spring. Compared with other elastic elements such as rubber, the spring has greater rigidity and is not easy to be damaged.

[0039] More detailed, such as Fig. 9As shown, an elastic element 4 is arranged between the shock-absorbing PDC tooth 1 and the bushing 5 to form a sliding connection, the limiter 6 cooperates with the limit groove 14 on the second supporting base 13 through the limit hole 51 of the bushing 5, and the drill blade 21 is connected to the bushing 5 by welding or interference fit; the elastic element 4 is one or two of a spring, rubber, and a disc spring and is arranged between the bushing 5 and the second supporting base 13.

[0040] like Figure 8 The figure shows a schematic diagram of the structure of the bushing 5. The bushing 5 supports the shock-absorbing PDC teeth 1 and connects the shock-absorbing PDC module 3 with the drill blade 21. The side wall of the bushing 5 is provided with a limiting hole 51 corresponding to the limiting groove 14.

[0041] The specific working principle of the shock-absorbing PDC module is as follows: during drilling, when the shock-absorbing PDC tooth 1 is drilling in the normal homogeneous rock formation 7, Fig.10 As shown, the elastic element 4 is compressed under the axial force generated by the interaction between the shock-absorbing PDC tooth 1 and the rock, and the rebound force generated by the compression reaches a balance with the axial force on the shock-absorbing PDC tooth 1. The shock-absorbing PDC tooth 1 scrapes the rock at a fixed penetration depth, thereby maintaining the stability of the drill bit during drilling; Fig.11 When the shock-absorbing PDC tooth 1 is subjected to a large load in the heterogeneous rock layer 71, the shock-absorbing PDC tooth 1 is subjected to the axial force component and compresses the elastic element 4. At the same time, the axial force component pushes the shock-absorbing PDC tooth 1 to shrink into the drill blade 21, thereby reducing the depth of the shock-absorbing PDC tooth 1 penetrating into the rock, and ultimately plays a role in reducing the impact and maintaining stable drilling of the drill bit.

[0042] The higher the drilling pressure, the lower the PDC teeth will be able to penetrate into the rock, but the longer it penetrates, the deeper the PDC teeth will penetrate.

[0043] like Figure 2 and Figure 3 They are respectively a shock-absorbing PDC plane tooth and a shock-absorbing PDC plane tooth module formed by a polycrystalline diamond layer 11 as a plane; Figure 4 and Figure 5 They are respectively a shock-absorbing PDC ridge tooth and a shock-absorbing PDC ridge tooth module in which the polycrystalline diamond layer 11 is ridge-shaped; Figure 6 and Figure 7They are shock-absorbing PDC Mercedes-Benz teeth and shock-absorbing PDC Mercedes-Benz tooth modules with a Mercedes-Benz-shaped polycrystalline diamond layer 11. The polycrystalline diamond layer 11 is one of plane, ridge, and Mercedes-Benz shapes or a combination thereof, and cutting teeth of different shapes match different strata, thereby broadening the application range of the drill bit.

[0044] like Fig.12 The drill blade 21 is provided with a tooth hole, and the tooth hole axis 151 coincides with the drill cutting profile normal 9. The tooth hole can be directly processed by drilling, which changes the conventional PDC drill bit tooth hole milling processing method, reduces the difficulty of PDC drill bit tooth hole processing, and improves the drill bit manufacturing efficiency.

[0045] The present invention is particularly suitable for use in oil and gas drilling. The shock-absorbing PDC drill bit 2 improves the PDC cutting teeth, which not only increases the service life of the drill bit, but also reduces the frequency of drilling, thereby greatly improving the economic benefits of the drill bit. The present invention has a simple structure and aims to achieve the stability of the penetration depth of the cutting teeth when scraping the formation through elastic elements and a special base shape (L-shape), which can reduce the instability of the drill bit working torque caused by the frequent changes in the penetration depth of the cutting teeth due to the fluctuation of the drilling pressure, and reduce the impact load on the cutting teeth when breaking heterogeneous formations, thereby improving the rock breaking efficiency of the drill bit and extending the life of the drill bit.

Claims

1. A PDC drill bit with damping teeth, comprising a drill bit body, blades and PDC teeth arranged on the blades, a water hole being arranged on the drill bit body, characterized in that: At least one of the PDC teeth is a shock-absorbing PDC module, which includes a shock-absorbing PDC tooth, a bushing, an elastic element, and a limiter. The shock-absorbing PDC tooth is composed of a polycrystalline diamond layer, a first supporting substrate and a second supporting substrate, the axes of the first supporting substrate and the second supporting substrate are L-shaped, an elastic element is arranged between the shock-absorbing PDC tooth and the bushing to form a sliding connection, the limiter is arranged between the bushing and the shock-absorbing PDC tooth, a tooth hole is opened on the blade, the axis of the tooth hole coincides with the normal of the cutting profile of the drill bit, and the blade and the bushing are connected by welding or interference fit.

2. A PDC drill bit with damping teeth according to claim 1, characterized in that: The axes of the first supporting base and the second supporting base are L-shaped, and the included angle α thereof is in the range of 90°<α<180°.

3. A PDC drill bit with damping teeth according to claim 1, characterized in that: The elastic element is one or two of a spring, rubber, and a disc spring.

4. A PDC drill bit with damping teeth according to claim 1, characterized in that: The polycrystalline diamond layer is in one of the following shapes: a plane shape, a roof shape, and a Mercedes-Benz shape.

5. A PDC drill bit with damping teeth according to claim 1, characterized in that: The shock-absorbing PDC teeth are arranged on a PDC-cone composite drill bit, a cross-scraping composite drill bit or an impact-scraping composite drill bit.

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