A self-vibrating PDC drill bit for directional deflection

Abstract

The present invention relates to the technical field of oil and gas exploration and development, and in particular to a self-vibrating PDC drill bit for directional deflection, comprising a joint body, a drill bit body and a vibration unit located inside the joint body; the vibration unit comprises a moving valve, a static valve, a rotating shaft, a bearing, a support ring and a driving member for driving the rotating shaft to rotate; the joint body is threadedly connected to the drill bit body; the outer ring of the bearing is clearance-matched with the joint body, and the inner ring of the bearing is transitionally matched with the rotating shaft; the support ring is threadedly connected to the joint body for supporting the bearing; the moving valve and the static valve are both eccentric valve bodies of the flow channel; the moving valve is fixed in the upper inner flow channel of the rotating shaft, and the static valve is fixed inside the flow channel of the joint body; when the rotating shaft rotates, relative rotation occurs between the moving valve and the static valve, and the flow channel area between the moving valve and the static valve changes periodically. The self-vibrating PDC drill bit can effectively solve the support pressure problem that occurs during the directional drilling process of conventional PDC drill bits.

Description

Technical Field

[0001] The invention relates to the technical field of oil and gas exploration and development, in particular to a self-vibrating PDC drill bit for directional deflection. Background Art

[0002] During the oil drilling process, directional drilling is sometimes performed due to engineering needs. Figure 8 , at this time, the upper part of the wellbore trajectory is a straight line, while the lower part has a certain curvature. When the angle between the well section with curvature and the straight well section, that is, the well deviation, becomes larger and larger, contact between the drill bit and the well wall is inevitable. PDC drill bit is a rock breaking tool widely used in the oil and gas exploration and development industry today. It effectively improves the mechanical drilling tool and shortens the drilling cycle. At present, in the process of directional drilling using conventional PDC drill bits, there are problems such as large friction and torque fluctuation, and auxiliary operations such as short-circuit start are required for multiple times, resulting in low stroke drilling speed and short drill bit life. Although PDC drill bits have a certain speed-up effect when used in directional bend sections with tools such as hydraulic oscillators, there is still a pressure-supporting phenomenon due to insufficient vibration force transmitted to the drill bit, which is difficult to fully meet the on-site needs. In engineering, roller bits are generally used for drilling in bend sections, but due to the presence of active components such as rolling bearings, the service life of roller bits is short, and sometimes it may take multiple trips to complete the drilling of the bend section, which is not conducive to reducing drilling costs. After analyzing the working principle of the roller drill bit, it was found that the axial vibration generated by the roller drill bit during the rock breaking process can relieve the support pressure. Therefore, in order to reduce the drilling cost, the PDC drill bit can be given axial impact capability to replace the roller drill bit in drilling the deflection section. At present, in the field of drilling, the hydraulic oscillator can generate axial hydraulic impact, but its equipment is long and cannot meet the requirements of higher deflection rate when used with the PDC drill bit. Summary of the invention

[0003] In order to solve the above technical problems, the present invention proposes a self-vibrating PDC drill bit for directional drilling, which can effectively solve the support pressure problem occurring during directional drilling of conventional PDC drill bits, reduce the number of tripping and drilling, improve drilling efficiency, and reduce drilling costs.

[0004] The present invention is achieved by adopting the following technical solutions:

[0005] A self-vibrating PDC drill bit for directional deflection, characterized in that it includes a joint body, a drill bit body and a vibration unit located inside the joint body; the vibration unit includes a movable valve, a static valve, a rotating shaft, a bearing, a support ring and a driving member for driving the rotating shaft to rotate; the joint body is threadedly connected to the drill bit body; the outer ring of the bearing is clearance-matched with the joint body, and the inner ring of the bearing is transitionally matched with the rotating shaft; the support ring is threadedly connected to the joint body for supporting the bearing; the movable valve and the static valve are both eccentric valve bodies of the flow channel; the movable valve is fixed in the upper inner flow channel of the rotating shaft, and the static valve is fixed inside the flow channel of the joint body; the driving member drives the rotating shaft and the movable valve to rotate, and relative rotation occurs between the movable valve and the static valve, and the flow channel area between the movable valve and the static valve changes periodically, and a periodic axial vibration force is formed through the water hammer impact effect, and the vibration force is transmitted to the support ring through the rotating shaft, and the support ring is transmitted to the joint body, and then transmitted to the drill bit body by the joint body.

[0006] The utility model also comprises a retaining spring, wherein the retaining spring is used for limiting the axial displacement of the static valve.

[0007] The driving member is an impeller, which is connected to the rotating shaft. The rotation of the impeller drives the rotating shaft to rotate.

[0008] The impeller is formed by machining high-strength stainless steel, and the surface of the joint inner hole of the joint body matching the impeller is provided with a wear-resistant material coating.

[0009] The wear-resistant material is cobalt-based WC alloy powder, and the coating is processed by laser cladding or thermal spraying.

[0010] The blade inclination angle of the impeller is 30°~60°.

[0011] The fluid channel in the middle of the rotating shaft adopts a grid design to form a grid-shaped channel, and the width of the grid-shaped channel matches the minimum passing size of the impeller.

[0012] The channel width of the grid shape is at least 2 mm smaller than the minimum passage dimension of the impeller.

[0013] The lower part of the joint body is also connected with a guide plate for guiding flow.

[0014] The length of the installed self-vibrating PDC drill bit is 450mm-600mm.

[0015] The impeller and the rotating shaft are connected by a clearance fit combined with a keyway.

[0016] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0017] 1. In the present invention, the limited space of the drill bit body is fully utilized, and the drilling fluid can be used as a power source. The axial vibration impact force is generated by changing the flow channel area of ​​the drill bit cavity, etc. The axial vibration impact force will convert static friction into dynamic friction, relieve the friction resistance of the drill tool near the drill bit, and can effectively alleviate the support pressure problem, improve the rock breaking efficiency of the drill bit in the directional section, thereby replacing the roller drill bit for drilling in the beveling section, avoiding the safety risks of loosening and falling of the roller parts, reducing the number of tripping and drilling, improving the drilling efficiency, and reducing the drilling cost. At the same time, periodic vibration will also play a role in assisting rock breaking.

[0018] Furthermore, compared with the prior art, the present invention adopts hydraulic impact, which is a flexible impact. Compared with mechanical impact, it has no mechanical collision and has better protection for the drill bit.

[0019] In the present invention, since both the moving valve and the static valve are eccentric valve bodies of the flow channel, the relative rotation between the moving valve and the static valve will cause the flow channel area between the moving valve and the static valve to change periodically, and the valve will open and close instantly with frequency, causing the fluid pressure in the inner flow channel to change. According to different formations, well depths and build-up rates under actual working conditions, the moving valve and the static valve can adopt a combination of different cut-off areas. With the increase of formation difficulty, well depth and build-up rate, the combination of the cut-off area between the moving valve and the static valve can be appropriately adjusted to increase the axial vibration force, and the vibration force can vary in the range of 10%-20% of the drilling pressure.

[0020] 2. It also includes a retaining spring, which can limit the axial displacement of the static valve, so that the coordination effect between the dynamic valve and the static valve is better.

[0021] 3. Since a complete axial vibration is generated every time the impeller rotates one circle, the rotation speed of the impeller is equivalent to the vibration frequency. Therefore, the vibration force type generated by the drill bit in the present invention can be high-frequency low-amplitude vibration. The period of high frequency and flow area change can be obtained through the structural design of the impeller, that is, by designing the blade inclination angle of the impeller. The blade inclination angle of the impeller can be modified accordingly according to the working environment. The axial high-frequency low-amplitude vibration generated by the self-vibrating drill bit under the water hammer effect can reduce the harmful axial vibration generated by the drill bit in the process of cutting the formation, thereby protecting the cutting teeth and obtaining a higher comprehensive footage.

[0022] 4. When the mud fluid passes through the vibration unit, due to the presence of a certain proportion of micro solid particles in the mud fluid, erosion will occur on the surface of the parts under the high-speed flow and the rapid scouring effect of the solid particles. The faster the mud fluid speed, the more obvious the erosion will be. When the key parts are severely eroded, it will affect the working parameters, causing performance degradation and even abnormal aging of the entire drill bit. In order to protect the normal working life of the drill bit, the impeller is machined from high-strength stainless steel, and the surface of the inner hole of the joint body that matches the impeller is coated with a wear-resistant material to increase the life of the parts.

[0023] 5. The fluid channel in the middle of the rotating shaft adopts a grid design, and the width of the grid-shaped channel matches the minimum passing size of the impeller, so as to avoid the impeller stopping due to blockage by large particles of solids, and at the same time, it can also achieve a good diversion effect.

[0024] 6. The lower part of the joint body is also connected with a guide plate, which has a good guide effect.

[0025] 7. Through the coordination of various structures, the length of the installed self-vibrating PDC drill bit is 450mm-600mm without reducing its function. Compared with the roller bit, it has a higher comprehensive footage during directional drilling, which can reduce the number of times to replace the drill bit. Compared with the traditional technical solution of hydraulic vibrator plus drill bit to solve the decompression problem, its length is much shorter, which can meet the directional drilling with higher slope rate. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] The present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments, wherein:

[0027] Figure 1 An exploded view of the present invention;

[0028] Figure 2 It is a schematic diagram of the exterior facade of the present invention;

[0029] Figure 3 It is a schematic diagram of the cross-sectional structure of the present invention;

[0030] Figure 4 It is a top view schematic diagram of the present invention;

[0031] Figure 5 It is a schematic diagram of the cross-sectional structure of the rotating shaft and the grid in the present invention;

[0032] Figure 6 It is a schematic diagram of the working principle of the vibration unit in the present invention;

[0033] Figure 7 A diagram showing the change in flow channel area between the dynamic valve and the static valve in the present invention;

[0034] Figure 8 It is a schematic diagram of directional drilling in the present invention;

[0035] Markings in the figure:

[0036] 1. Connector body, 2. Drill bit body, 3. Moving valve, 4. Static valve, 5. Rotating shaft, 6. Bearing, 7. Support ring, 8. Impeller, 9. Guide plate. DETAILED DESCRIPTION

[0037] Example 1

[0038] As a basic embodiment of the present invention, the present invention includes a self-vibrating PDC drill bit for directional deflection, including a joint body 1, a drill bit body 2 and a vibration unit located inside the joint body 1. The vibration unit includes a dynamic valve 3, a static valve 4, a rotating shaft 5, a bearing 6, a support ring 7 and a driving member for driving the rotating shaft 5 to rotate. The joint body 1 is threadedly connected to the drill bit body 2. The outer ring of the bearing 6 is clearance-fitted with the joint body 1, and the inner ring of the bearing 6 is transitionally fitted with the rotating shaft 5. The support ring 7 is threadedly connected to the joint body 1 for supporting the bearing 6. The dynamic valve 3 and the static valve 4 are both eccentric valve bodies of the flow channel. The dynamic valve 3 is fixed in the upper inner flow channel of the rotating shaft 5, and the static valve 4 is fixed inside the flow channel of the joint body 1. The driving member drives the rotating shaft 5 and the movable valve 3 to rotate, and the movable valve 3 and the static valve 4 rotate relative to each other. The flow channel area between the movable valve 3 and the static valve 4 changes periodically, and a periodic axial vibration force is formed through the water hammer impact effect. The vibration force is transmitted to the support ring 7 through the rotating shaft 5, and the support ring 7 is transmitted to the joint body 1, and then transmitted to the drill bit body 2 by the joint body 1.

[0039] Example 2

[0040] As a preferred embodiment of the present invention, the present invention includes a self-vibrating PDC drill bit for directional deflection, including a joint body 1, a drill bit body 2 and a vibration unit located inside the joint body 1. The vibration unit includes a dynamic valve 3, a static valve 4, a rotating shaft 5, a bearing 6, a support ring 7 and a driving member for driving the rotating shaft 5 to rotate. The joint body 1 is threadedly connected to the drill bit body 2.

[0041] The outer ring of the bearing 6 is in clearance fit with the joint body 1, and the inner ring of the bearing 6 is in transition fit with the rotating shaft 5. The support ring 7 is threadedly connected to the joint body 1 for supporting the bearing 6. The movable valve 3 and the static valve 4 are both eccentric valve bodies of the flow channel. The movable valve 3 is fixed in the upper inner flow channel of the rotating shaft 5, and the specific fixing method can be an interference fit connection. The static valve 4 is fixed inside the flow channel of the joint body 1, and further, the axial displacement of the static valve 4 can be limited by setting a retaining spring.

[0042] The driving member is an impeller 8, and the impeller 8 is connected to the rotating shaft 5, and specifically can be connected by interference fit. The drilling fluid impacts the impeller 8 through the flow channel in the moving valve 3, the static valve 4, and the rotating shaft 5, and the impeller 8 rotates, driving the rotating shaft 5 and the moving valve 3 to rotate, so that the moving valve 3 and the static valve 4 rotate relative to each other, and the flow channel area between the moving valve 3 and the static valve 4 changes periodically. In order to increase the service life of the impeller 8 and the joint body 1, the impeller 8 is machined with high-strength stainless steel, and the surface of the joint inner hole of the joint body 1 matching the impeller 8 is provided with a wear-resistant material coating.

[0043] The new type of PDC drill bit is more popular with people, more popular with locals, and has a very low maintenance, low-friction effect.It has a lot of advantages, being very easy to get stuck in a drill hole.The PDC drill bit is very good at drilling, but it can also be used to drill deeper into the wellhead, so it is more likely to get stuck in a hole.

[0044] Example 3

[0045] As another preferred embodiment of the present invention, the present invention includes a self-vibrating PDC drill bit for directional deflection, including a joint body 1, a drill bit body 2, and a vibration unit located inside the joint body 1. The vibration unit includes a dynamic valve 3, a static valve 4, a rotating shaft 5, a bearing 6, a support ring 7, a guide plate 9, and a driving member for driving the rotating shaft 5 to rotate.

[0046] The joint body 1 is threadedly connected to the drill body 2. The outer ring of the bearing 6 is clearance-fitted with the joint body 1, and the inner ring of the bearing 6 is transitionally fitted with the rotating shaft 5. The support ring 7 is threadedly connected to the joint body 1 for supporting the bearing 6. The movable valve 3 and the static valve 4 are both eccentric valve bodies for the flow channel. The movable valve 3 is fixed in the upper inner flow channel of the rotating shaft 5, and the specific fixing method can be a brazing connection. The static valve 4 is fixed inside the flow channel of the joint body 1. The guide plate 9 is connected to the lower part of the joint body 1 for achieving diversion.

[0047] The driving member may be a turbine, which is connected to the rotating shaft 5, so that the rotation of the turbine drives the rotating shaft 5 to rotate. The fluid channel in the middle of the rotating shaft 5 adopts a grid design.

[0048] After the drilling fluid passes through the flow channels in the dynamic valve 3, the static valve 4 and the rotating shaft 5, it drives the driving member to rotate, and further drives the rotating shaft 5 and the dynamic valve 3 to rotate. The dynamic valve 3 and the static valve 4 rotate relative to each other, and the flow channel area between the dynamic valve 3 and the static valve 4 changes periodically. A periodic axial vibration force is formed through the water hammer impact effect. The vibration force is transmitted to the support ring 7 through the rotating shaft 5, and the support ring 7 is transmitted to the joint body 1, and then transmitted to the drill bit body 2 by the joint body 1.

[0049] Example 4

[0050] As the best embodiment of the present invention, refer to the attached specification. Figure 1 The present invention includes a self-vibrating PDC drill bit for directional deflection, including a joint body 1, a drill bit body 2 and a vibration unit located inside the joint body 1. The vibration unit includes a moving valve 3, a static valve 4, a rotating shaft 5, a bearing 6, a support ring 7, a guide plate 9 and a driving member for driving the rotating shaft 5 to rotate. The driving member can be an impeller 8.

[0051] Refer to the instruction manual Figure 2 ~Instructions attached Figure 4, the movable valve 3 and the static valve 4 are both eccentric valve bodies of the flow channel. The movable valve 3 is fixed in the flow channel of the upper part of the rotating shaft 5, and the movable valve 3 is opposite to the rotating shaft 5. The fixing method can be threaded connection. The bearing 6, the support ring 7 and the impeller 8 are installed in sequence at the lower part of the rotating shaft 5. The outer ring of the bearing 6 is clearance-matched with the joint body 1, and the inner ring of the bearing 6 is transitionally matched with the rotating shaft 5. The support ring 7 is threadedly connected with the joint body 1. After the support ring 7 applies a certain buckling torque, the bearing 6 and the rotating shaft 5 are fixed axially inside the joint body 1, but the rotating shaft 5 can rotate freely. The impeller 8 and the rotating shaft 5 are connected by a clearance fit combined with a keyway. Specifically, it can be: the impeller 8 and the rotating shaft 5 are matched with a gap, and then the impeller 8 is fixed by a spline, so that the impeller 8 rotates with the rotating shaft 5. Further, the static valve 4 is fixed inside the flow channel of the joint body 1, and its axial displacement is limited by a retaining spring. A guide plate 9 for guiding flow is installed at the lower part of the joint body 1. Furthermore, the joint body 1 equipped with the vibration unit is connected to the drill bit body 2 through threads to form a self-vibrating PDC drill bit.

[0052] Refer to the instruction manual Figure 5 , the fluid channel in the middle of the rotating shaft 5 adopts a grid design to form a grid-shaped channel, and the width of the grid-shaped channel matches the minimum passing size of the impeller 8. The minimum width of the grid-shaped channel width is more than 2mm smaller than the minimum passing size of the impeller 8, so as to prevent the impeller 8 from stopping due to large solid particles blocking. When the mud fluid passes through the vibration unit, due to the presence of a certain proportion of micro solid particles in the mud fluid, erosion will occur on the surface of the parts under the effect of high-speed flow and rapid scouring of solid particles. The faster the mud fluid speed, the more obvious the erosion will be. When the key parts are severely eroded, it will affect the working parameters, cause performance degradation, and even cause abnormal aging of the entire drill bit. In order to protect the normal working life of the drill bit, special processes and materials are used to extend the life of the impeller 8 and the inner hole of the joint body 1 that matches the impeller 8. The impeller 8 is formed by machining with high-strength stainless steel, and the inner hole of the joint is reinforced with a surface wear-resistant material coating. The coating process can be laser cladding or thermal spraying. The wear-resistant material adopts cobalt-based WC alloy powder, wherein WC specifically refers to tungsten carbide.

[0053] Due to the exquisite coordination between the various structures in this embodiment, the length of the installed self-vibrating PDC drill bit is 450mm-600mm. Compared with the traditional technical solution of solving the decompression problem of a hydraulic oscillator plus a drill bit, its length is much shorter and can meet the requirements of directional drilling with a higher inclination rate.

[0054] During the actual operation of the self-vibrating drill, refer to the instructions attached. Figure 6 The drilling fluid impacts the impeller 8 through the flow channel inside the moving valve 3, the static valve 4 and the rotating shaft 5. The rotation of the impeller 8 drives the rotating shaft 5 and the moving valve 3 to rotate. Figure 7 , the relative rotation between the moving valve 3 and the static valve 4 will cause the flow channel area between the moving valve 3 and the static valve 4 to change periodically, and the valve will open and close instantly with a certain frequency, causing the fluid pressure in the inner flow channel to change, thereby forming a periodic axial vibration force through the water hammer impact effect. Further, the vibration force is transmitted to the support ring 7 through the rotating shaft 5, and the support ring 7 is transmitted to the joint body 1, and then transmitted to the drill bit body 2 by the joint body 1, so as to achieve the purpose of axial vibration of the drill bit. The axial vibration force will convert static friction into dynamic friction, relieve the friction resistance of the drill tool near the drill bit, thereby solving the pressure support problem. At the same time, the periodic vibration will also play a role in assisting rock breaking.

[0055] In order to make the axial vibration force finally form high-frequency low-amplitude vibration, the blade inclination angle of the impeller 8 can be designed. The blade inclination angle of the impeller 8 can be 30°~60°, and the specific angle can be modified accordingly according to the actual working environment, for example, according to the working displacement.

[0056] According to different formations, well depths and build-up rates under actual working conditions, the dynamic valve 3 and the static valve 4 can adopt different combinations of cut-off areas. With the increase of formation difficulty, well depth and build-up rate, the combination of cut-off areas between the dynamic valve 3 and the static valve 4 can be appropriately adjusted to increase the axial vibration force, and the vibration force varies within a range of 10%-20% of the drilling pressure. The type of vibration force generated by the drill bit in the present invention is high-frequency low-amplitude vibration, and the period of high frequency and flow channel area change can be obtained through the structural design of the impeller 8. The axial high-frequency low-amplitude vibration generated by the self-vibrating drill bit under the water hammer effect can reduce the harmful axial vibration generated by the drill bit in the process of cutting the formation, thereby protecting the cutting teeth and obtaining a higher comprehensive footage.

[0057] In summary, after reading the present invention document, ordinary technicians in this field can make various other corresponding transformation schemes based on the technical scheme and technical concept of the present invention without creative mental labor, which all fall within the scope of protection of the present invention.

Claims

1. A self-vibrating PDC drill bit for directional deflection, Features: The invention comprises a joint body (1), a drill body (2) and a vibration unit located inside the joint body (1); the vibration unit comprises a movable valve (3), a static valve (4), a rotating shaft (5), a bearing (6), a support ring (7) and a driving member for driving the rotating shaft (5) to rotate; the joint body (1) is threadedly connected to the drill body (2); the outer ring of the bearing (6) is clearance-fitted with the joint body (1), and the inner ring of the bearing (6) is transitionally fitted with the rotating shaft (5); the support ring (7) is threadedly connected to the joint body (1) for supporting the bearing (6); the movable valve (3) and the static valve (4) are both eccentric valve bodies; the movable valve (3) is fixed in the upper inner flow channel of the rotating shaft (5), and the static valve (4) is fixed inside the flow channel of the joint body (1). The driving member drives the rotating shaft (5) and the movable valve (3) to rotate, and the movable valve (3) and the static valve (4) rotate relative to each other, and the flow channel area between the movable valve (3) and the static valve (4) changes periodically, and a periodic axial vibration force is formed through the water hammer impact effect. The vibration force is transmitted to the support ring (7) through the rotating shaft (5), and the support ring (7) is transmitted to the joint body (1), and then transmitted to the drill bit body (2) by the joint body (1); the driving member is an impeller (8), and the impeller (8) is connected to the rotating shaft (5). The rotation of the impeller (8) drives the rotating shaft (5) to rotate; the fluid channel in the middle of the rotating shaft (5) adopts a grid design to form a grid-shaped channel, and the width of the grid-shaped channel matches the minimum passing size of the impeller (8).

2. A self-vibrating PDC drill bit for directional deflection according to claim 1, Features: It also includes a retaining spring, which is used to limit the axial displacement of the static valve (4).

3. A self-vibrating PDC drill bit for directional deflection according to claim 1, Features: The impeller (8) is formed by machining high-strength stainless steel, and the surface of the joint inner hole of the joint body (1) matching the impeller (8) is provided with a wear-resistant material coating.

4. A self-vibrating PDC drill bit for directional deflection according to claim 3, Features: The wear-resistant material is cobalt-based WC alloy powder, and the coating is processed by laser cladding or thermal spraying.

5. A self-vibrating PDC drill bit for directional deflection according to claim 4, Features: The blade inclination angle of the impeller (8) is 30° to 60°.

6. A self-vibrating PDC drill bit for directional deflection according to claim 1, Features: The width of the grid-shaped channel is at least 2 mm smaller than the minimum passage dimension of the impeller (8).

7. A self-vibrating PDC drill bit for directional deflection according to claim 1, Features: The lower part of the joint body (1) is also connected to a guide plate (9) for guiding flow.

8. A self-vibrating PDC drill bit for directional deflection according to claim 1, Features: The length of the installed self-vibrating PDC drill bit is 450mm-600mm.

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