Drill torque change self-adjusting device

Abstract

The invention belongs to the technical field of oil and gas drilling, and particularly relates to a drill torque change self-adjusting device. The drill torque change self-adjusting device comprises a cylinder body, a piston rod is movably arranged in the cylinder body in a sealed mode in the axial direction, the upper end of the piston rod extends out of the cylinder body, a piston body is fixedly arranged at the lower end of the piston rod, and the cylinder body is divided into an upper cavity and a middle cavity through the piston body. The piston body is provided with at least one check valve and at least one damping hole, the upper cavity and the middle cavity are communicated through the check valve and the damping hole, and the check valve allows fluid to flow downwards. The change amplitude of the depth of the drill bit penetrating into the rock can be controlled, so that the torque stability of the drill bit is improved, the stability of the drill bit in the drilling process is improved, and the service life of the drill bit is prolonged.

Description

Technical Field

[0001] The invention belongs to the technical field of oil and gas drilling, and in particular relates to a drill bit torque change self-adjusting device. Background Art

[0002] PDC drill bits can achieve good results in soft to medium-hard formations and are widely used in oil and geological drilling. However, in some medium to hard formations, especially in heterogeneous formations, the depth of the PDC drill bit's cutting teeth into the formation rock will vary greatly due to different formation lithology and drilling pressure. This large change in penetration depth will lead to a sharp change in the drill bit torque, which will cause the drill bit's speed to increase or decrease significantly, or even stagnate and reverse. This unstable working state will cause serious impact damage to the drill bit's cutting teeth, which will lead to the drill bit being scrapped and seriously affect the drill bit's service life.

[0003] Therefore, improving the torque stability of the drill bit during the drilling process is of great significance to improving the stability of the drill bit and the service life of the drill bit. Summary of the invention

[0004] In response to the technical problems mentioned above, the present invention aims to propose a self-adjusting device for drill bit torque variation, which can control the variation amplitude of the drill bit's penetration depth into the rock, thereby improving the stability of the drill bit torque, and further improving the stability of the drill bit during the drilling process and the service life of the drill bit.

[0005] According to the present invention, a drill bit torque change self-adjusting device is provided, including a cylinder body, in which a piston rod is provided with an axially movable seal, the upper end of the piston rod extends out of the cylinder body, and a piston body is fixedly provided at the lower end of the piston rod, the piston body divides the cylinder body into an upper cavity and a middle cavity, and at least one one-way valve and at least one damping hole that connect the upper cavity and the middle cavity are provided on the piston body, and the one-way valve allows the fluid to flow downward.

[0006] The drill bit torque change self-adjusting device provided by the present invention is installed on the top of the drill bit. During the drilling process, the piston head at the top of the piston rod can contact the rock. As the depth of the drill bit entering the rock is different, the degree of expansion and contraction of the piston rod is different. When the depth of the drill bit entering the rock increases, the rock will push the piston rod to move in the direction of the middle cavity, thereby increasing the volume of the upper cavity and reducing the volume of the middle cavity. After the volume of the upper cavity increases, negative pressure is generated, and after the volume of the middle cavity decreases, positive pressure is generated. The fluid in the middle cavity will have a tendency to flow toward the upper cavity. Since the one-way valve on the piston body hinders the flow of the fluid in this direction, the fluid can only flow from the middle cavity to the upper cavity through the damping hole on the piston body. The resistance of the damping hole will generate a force opposite to the direction of movement of the piston body to the middle cavity, thereby hindering the movement of the piston body, and then reducing the depth change of the drill bit entering the rock. The depth change amplitude of the drill bit entering the rock is reduced, which can reduce the amplitude of the change of the drill bit torque, thereby increasing the service life of the drill bit. In this embodiment, the area of ​​the upper end of the piston body that is subjected to the fluid pressure is smaller than the area of ​​the lower end that is subjected to the fluid pressure. When the rock no longer pushes the piston rod, the piston body will move upward and reset under the pressure difference of the fluid. During the reset process, the excess fluid in the upper cavity can flow to the middle cavity through the one-way valve on the piston body.

[0007] In a preferred embodiment, a middle valve assembly is fixedly provided in the cylinder body, a lower piston is axially movably provided in the cylinder body via an elastic member, the middle cavity is between the middle valve assembly and the piston body, a lower cavity is formed between the lower part of the middle valve assembly and the lower piston, at least one one-way valve and at least one damping hole connecting the middle cavity and the lower cavity are provided on the middle valve assembly, and the one-way valve allows the fluid to flow upward.

[0008] In a preferred embodiment, the piston body includes a tapered cylinder and a cylinder body, wherein the cylinder body is fixedly arranged at the lower end of the tapered cylinder, and an outer wall of the cylinder body is sealed with an inner wall of the cylinder body.

[0009] In a preferred embodiment, at least one damping hole and at least one one-way valve connecting the upper cavity and the middle cavity are provided on the conical cylinder.

[0010] In a preferred embodiment, the middle valve assembly comprises:

[0011] A valve seat sealingly fixed in the cylinder body;

[0012] A one-way valve core is arranged in the valve seat by a valve core spring; and

[0013] A damping hole is arranged on the valve seat and connects the middle cavity and the lower cavity.

[0014] In a preferred embodiment, the one-way valve core is arranged along the central axis of the valve seat.

[0015] In a preferred embodiment, a spring pressure cover is arranged below the lower piston, the spring pressure cover is fixedly connected to the cylinder body, and an energy storage spring is coaxially arranged between the spring pressure cover and the lower piston, and the axial ends of the energy storage spring contact the lower piston and the spring pressure cover respectively.

[0016] In a preferred embodiment, the energy storage spring includes a plurality of disc springs arranged axially in sequence.

[0017] In a preferred embodiment, a spring core shaft is coaxially fixedly arranged at the lower part of the lower piston, the lower part of the spring core shaft is movably arranged in the spring pressure cover, and the energy storage spring is sleeved on the spring core shaft.

[0018] In a preferred embodiment, a sealing plug is fixedly provided on the inner side of the upper portion of the cylinder body, and the piston rod is sealingly and slidingly connected to the sealing plug.

[0019] Compared with the prior art, the present application has the following advantages.

[0020] The present invention is arranged at the top of the drill bit. During the drilling process, the top of the piston rod will contact the rock. The depth of the drill bit penetrating into the rock will affect the movement of the piston rod. When the penetration depth increases, the rock will push the piston rod to move downward. During the movement of the piston rod, the upper cavity increases to generate negative pressure, and the middle cavity decreases to generate positive pressure. However, the fluid in the middle cavity can only flow through the damping hole on the piston body, thereby generating a force that hinders the downward movement of the piston rod, thereby hindering the further increase of the penetration depth of the drill bit.

[0021] After the cavity is reduced in the present invention, a portion of the fluid flows to the lower cavity through the middle valve assembly, so that the lower piston moves downward, compresses the energy storage spring, stores a portion of energy, and can accelerate the reset of the piston rod. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] The present invention will be described below with reference to the accompanying drawings.

[0023] Figure 1 A schematic diagram showing an embodiment of a drill bit torque variation self-adjusting device according to the present invention;

[0024] Figure 2 A cross-sectional schematic diagram showing an embodiment of a drill bit torque variation self-adjusting device according to the present invention being installed on a drill bit;

[0025] Figure 3 A schematic top view showing an embodiment of a drill bit torque variation self-adjusting device according to the present invention being installed on a drill bit.

[0026] In the figure:

[0027] 1. Cylinder body;

[0028] 21. Piston rod;

[0029] 22, piston body; 221, tapered cylinder; 222, cylinder body;

[0030] 23. Piston head;

[0031] 24. Upper valve assembly;

[0032] 31. upper cavity; 32. middle cavity; 33. lower cavity;

[0033] 4. Middle valve assembly; 41. Valve seat; 42. One-way valve core; 43. Valve core spring;

[0034] 5. Lower piston; 51. Spring gland; 52. Energy storage spring; 53. Spring mandrel;

[0035] 61. Sealing thread plug; 62. Bottom thread plug;

[0036] 7. Drill bit; 71. Cutting teeth;

[0037] 8. Rocks;

[0038] 100. Drill bit torque change self-adjusting device.

[0039] In the present application, all drawings are schematic drawings, which are only used to illustrate the principles of the present invention and are not drawn according to the actual scale. DETAILED DESCRIPTION

[0040] The present invention will be described below with reference to the accompanying drawings.

[0041] It should be noted that the directional terms or qualifiers "upper", "lower", "front", "back", "left", "right", etc. used in this application are all relative to the referenced Figure 1 They are not intended to define the absolute positions of the components involved, but may vary depending on the specific circumstances.

[0042] Figure 1 The structure of the drill bit torque change self-adjusting device 100 provided according to the present invention is shown. Figure 1 As shown, the drill bit torque variation self-adjusting device 100 comprises a cylinder body 1, and the cylinder body 1 is configured in a cylindrical barrel shape.

[0043] A piston rod 21 is provided in the cylinder body 1 in an axially movable and sealed manner. The upper end of the piston rod 21 extends out of the cylinder body 1, and the upper end of the piston rod 21 is used to contact the rock during drilling. A piston body 22 is fixedly provided at the lower end of the piston rod 21, and the outer wall of the piston body 22 is movably and sealedly connected to the inner wall of the cylinder body 1, so that the piston body 22 divides the cylinder body 1 into an upper cavity 31 and a middle cavity 32, that is, the upper part of the piston body 22 is the upper cavity 31, and the lower part of the piston body 22 is the middle cavity 32. At least one check valve (not shown in the figure) and at least one damping hole (not shown in the figure) are provided on the piston body 22 to connect the upper cavity 31 and the middle cavity 32. The check valve allows the fluid to flow downward, that is, the fluid in the upper cavity 31 can flow into the middle cavity 32 through the check valve.

[0044] Figure 1 The upper valve assembly 24 includes at least one one-way valve and at least one damping hole, and its specific structure is similar to that of the middle valve assembly 4.

[0045] In a preferred embodiment, a piston head 23 is coaxially fixedly disposed on the top of the piston rod 22 .

[0046] Combination Figure 2 and Figure 3 As shown, the drill bit torque change self-adjusting device 100 provided by the present invention is installed on the top of the drill bit 7. During the drilling process, the piston head 23 on the top of the piston rod 22 can contact the rock 8. As the depth of the drill bit 7 entering the rock 8 is different, the degree of expansion and contraction of the piston rod 22 is different. When the depth of the drill bit 7 entering the rock 8 increases, the rock 8 will push the piston rod 22 to move in the direction of the middle cavity 32, thereby increasing the volume of the upper cavity 31 and reducing the volume of the middle cavity 32. After the volume of the upper cavity 31 increases, negative pressure is generated, and after the volume of the middle cavity 32 decreases, positive pressure is generated. The fluid in the middle cavity 32 will have a tendency to flow toward the upper cavity 31. Since the one-way valve on the piston body 22 hinders the flow of the fluid in this direction, the fluid can only flow from the middle cavity 32 to the upper cavity 31 through the damping hole on the piston body 22. The resistance of the damping hole will generate a force opposite to the direction of the piston body 22 moving toward the middle cavity 32, thereby hindering the movement of the piston body 22, and then reducing the change in the depth of the drill bit 7 entering the rock 8. The depth variation of the drill bit 7 into the rock 8 is reduced, which can reduce the variation of the torque of the drill bit 7, thereby increasing the service life of the drill bit 7. In this embodiment, the area of ​​the upper end of the piston body 22 that bears the fluid pressure is smaller than the area of ​​the lower end that bears the fluid pressure. When the rock 8 no longer pushes the piston rod 22, the piston body 22 will move upward and reset under the pressure difference of the fluid. During the reset process, the excess fluid in the upper cavity 31 can flow to the middle cavity 32 through the one-way valve on the piston body 22.

[0047] According to the present invention, in a preferred embodiment, a middle valve assembly 4 is fixedly arranged in the cylinder body 1, and at the same time, a lower piston 5 is movably arranged in the cylinder body 1 along the axial direction through an elastic member, and the lower piston 5 is located below the middle valve assembly 4. A middle cavity 32 is formed between the middle valve assembly 4 and the piston body 22, and a lower cavity 33 is formed between the lower part of the middle valve assembly 4 and the lower piston 5. At least one check valve and at least one damping hole (not shown in the figure) are arranged on the middle valve assembly 4 to connect the middle cavity 32 and the lower cavity 33. The check valve allows the fluid to flow upward, that is, the fluid in the lower cavity 33 can flow into the middle cavity 32 through the check valve.

[0048] In this setting, when the piston rod 21 moves downward, part of the fluid in the middle cavity 32 flows to the upper cavity 31 through the damping hole on the piston body 22, and part of the fluid flows to the lower cavity 33 through the damping hole on the middle valve assembly 4. The increase in the fluid in the lower cavity 33 will push the lower piston 5 to move downward, thereby increasing the elastic potential energy of the elastic member connected to the lower piston 5. During the drilling process, the downward movement and reset process of the piston rod 21 needs to be very rapid. During the reset process of the piston rod 21, the lower piston 5 is quickly reset under the elastic force of the elastic member, so that the fluid in the lower cavity 33 quickly flows to the middle cavity 32 through the one-way valve on the middle valve assembly 4. The pressure of the middle cavity 32 increases, which can speed up the reset of the piston rod 21.

[0049] In a preferred embodiment, the piston body 22 includes a tapered cylinder 221 and a cylinder body 222. The upper tip of the tapered cylinder 221 is coaxially fixedly connected to the piston rod 21. The cylinder body 222 is cylindrical and coaxially fixedly arranged at the lower end of the tapered cylinder 221. The outer wall of the cylinder body 222 is connected to the inner wall of the cylinder body 1 in a sliding sealing manner.

[0050] At least one damping hole and at least one one-way valve of the piston body 22 for connecting the upper cavity 31 and the middle cavity 32 are both arranged on the conical cylinder 221 , so that the central axes of the damping hole and the one-way valve are inclined relative to the piston rod 21 .

[0051] In a specific embodiment, the middle valve assembly 4 includes a valve seat 41, a one-way valve core 42 and a valve core spring 43. The outer wall of the valve seat 41 is sealed and fixed to the inner wall of the cylinder body 1, and the one-way valve core 42 is arranged in the valve seat 41 through the valve core spring 43. The valve core spring 43 and the one-way valve core 42 play the role of a one-way valve. The damping hole connecting the middle cavity 32 and the lower cavity 33 of the middle valve assembly 4 is arranged on the valve seat 41.

[0052] It should be noted that the middle valve assembly 4 in this embodiment only provides a schematic structure of a one-way valve, and is not intended to limit the structural protection scope of the middle valve assembly 4 of the present invention.

[0053] In a preferred embodiment, the one-way valve core 42 is disposed along the central axis of the valve seat 41 .

[0054] According to the present invention, in a specific embodiment, a spring pressure cover 51 is provided below the lower piston 5, the spring pressure cover 51 is provided in a cylindrical shape, and the outer wall of the spring pressure cover 51 is fixedly connected to the cylinder body 1. An energy storage spring 52 is coaxially provided between the spring pressure cover 51 and the lower piston 5, and the axial ends of the energy storage spring 52 contact the lower piston 5 and the spring pressure cover 51 respectively.

[0055] In a preferred embodiment, the energy storage spring 52 includes a plurality of disc springs arranged in sequence in the axial direction. Under this arrangement, a plurality of disc springs arranged in sequence can store sufficient elastic potential energy.

[0056] According to the present invention, in a preferred embodiment, a spring mandrel 53 is coaxially fixedly arranged at the lower part of the lower piston 5, and the spring mandrel 53 is arranged in a cylindrical shape. The upper end of the spring mandrel 53 extends into the interior of the lower piston 5 and is fixedly connected. The lower part of the spring mandrel 53 is movably arranged in the spring gland 51, and the energy storage spring 52 is sleeved on the spring mandrel 53. The spring mandrel 53 can play a guiding role for the lower piston 5, and can keep the energy storage spring 52 and the lower piston 5 coaxial.

[0057] In a specific embodiment, a sealing plug 61 is fixedly arranged on the inner side of the upper part of the cylinder body 1, the outer wall of the sealing plug 61 is sealed and fixed to the inner wall of the cylinder body 1, the piston rod 21 is coaxially inserted into the sealing plug 61, and the piston rod 21 is sealed and slidably connected to the sealing plug 61. A bottom plug 62 is arranged on the inner side of the lower part of the cylinder body 1, the outer wall of the bottom plug 62 is sealed and fixed to the inner wall of the cylinder body 1, and the upper end surface of the bottom plug 62 contacts the lower end surface of the spring pressure cover 51.

[0058] The working principle of the drill bit torque variation self-adjusting device 100 provided according to the present invention is as follows.

[0059] The drill bit torque variation self-adjusting device 100 is arranged inside the top end of the drill bit 7, and the central axis of the drill bit torque variation self-adjusting device 100 can be inclined relative to the central axis of the drill bit 7. Preferably, the central axis of the drill bit torque variation self-adjusting device 100 is parallel to the central axis of the drill bit 7. In the absence of external force, at least part of the length of the piston head 23 is located outside the drill bit 7, and preferably, the upper end of the piston head 23 is flush with the upper end of the cutting tooth 71.

[0060] When the drill bit 7 starts to drill, as the drill bit 7 eats into the rock 8, the rock 8 begins to generate thrust on the piston head 23, and the piston rod 21 moves downward to drive the piston body 22 downward. The downward movement of the piston body 22 changes the volume of the upper, middle and lower cavities in the cylinder body 1, and there is hydraulic oil in the three cavities.

[0061] The volume of the upper cavity 31 increases, a negative pressure is formed in the cavity, and the volume of the middle cavity 32 decreases to form a positive pressure, and the hydraulic oil in the middle cavity 32 flows into the upper cavity 31 through the damping hole of the upper valve assembly 24. At the same time, the hydraulic oil in the middle cavity 32 flows into the lower cavity 33 through the damping hole of the middle valve assembly 4 under high pressure. Under the action of hydraulic pressure, the hydraulic oil in the lower cavity 33 pushes the lower piston 5 downward, and the lower piston 5 compresses the energy storage spring 52. Since the hydraulic oil is limited by the size of the damping hole of the upper valve assembly 24 and the pressure of the energy storage spring 52, the greater the downward speed of the piston rod 21, the greater the damping. Therefore, the greater the pressure at the top of the piston rod 21, the greater the reaction force of the hydraulic oil on its piston body 22. Through this damping effect, the downward speed of the piston rod 21 is controlled, thereby slowing down the depth change of the drill bit 7.

[0062] When there is no pressure on the top of the piston rod 21, the energy storage spring 52 pushes the lower piston 5 upward, the volume of the lower cavity 33 decreases, the pressure in the lower cavity 33 increases, forming high pressure, and the hydraulic oil quickly flows into the middle cavity 32 through the large channel of the one-way valve core 42 of the middle valve assembly 4. The pressure in the middle cavity 32 increases, and the piston body 22 is pushed upward under the action of pressure, thereby reducing the volume of the upper cavity 31. The pressure in the upper cavity 31 increases, and the hydraulic oil quickly flows back to the middle cavity 32 from the upper cavity 31 through the large channel of the one-way valve of the upper valve assembly 24, pushing the piston body 22 to drive the piston rod 21 upward, so that the piston rod 21 quickly returns to its initial height.

[0063] In the description of the present invention, it should be understood that the terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of the features. In the description of the present invention, the meaning of "plurality" is two or more, unless otherwise clearly and specifically defined.

[0064] In the present invention, unless otherwise clearly specified and limited, the terms "installed", "connected", "connected", "fixed" and the like should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be an indirect connection through an intermediate medium, or it can be the internal communication of two components. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0065] In the description of this specification, the description with reference to the terms "one embodiment", "some embodiments", "examples", "specific examples", or "some examples" means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representation of the above terms does not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described may be combined in any one or more embodiments or examples in a suitable manner.

[0066] Finally, it should be noted that the above is only a preferred embodiment of the present invention and does not constitute any limitation to the present invention. Although the present invention has been described in detail with reference to the aforementioned embodiments, it is still possible for a person skilled in the art to modify the technical solutions described in the aforementioned embodiments or to replace some of the technical features therein by equivalents. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A drill bit torque change self-adjusting device, It is characterized in that The invention comprises a cylinder body (1), a piston rod (21) is provided in the cylinder body (1) in an axially movable sealing manner, the upper end of the piston rod (21) protrudes out of the cylinder body (1), a piston body (22) is fixedly provided at the lower end of the piston rod (21), the piston body (22) divides the cylinder body (1) into an upper cavity (31) and a middle cavity (32), and at least one one-way valve and at least one damping hole are provided on the piston body (22) for connecting the upper cavity (31) and the middle cavity (32), and the one-way valve allows the fluid to flow downward.

2. The drill bit torque change self-adjusting device according to claim 1, It is characterized in that A middle valve assembly (4) is fixedly arranged in the cylinder body (1), and a lower piston (5) is axially movably arranged in the cylinder body (1) via an elastic member. The middle cavity (32) is between the middle valve assembly (4) and the piston body (22), and a lower cavity (33) is formed between the lower part of the middle valve assembly (4) and the lower piston (5). At least one check valve and at least one damping hole are arranged on the middle valve assembly (4) to connect the middle cavity (32) and the lower cavity (33), and the check valve allows fluid to flow upward.

3. The drill bit torque change self-adjusting device according to claim 1 or 2, It is characterized in that The piston body (22) comprises a conical cylinder (221) and a cylinder body (222), wherein the cylinder body (222) is fixedly arranged at the lower end of the conical cylinder (221), and an outer wall of the cylinder body (222) is sealed with an inner wall of the cylinder body (1).

4. The drill bit torque change self-adjusting device according to claim 3, It is characterized in that At least one damping hole and at least one one-way valve connecting the upper cavity (31) and the middle cavity (32) are provided on the conical cylinder (221).

5. The drill bit torque change self-adjusting device according to claim 2, It is characterized in that The middle valve assembly (4) comprises: A valve seat (41) sealed and fixed in the cylinder body (1); A one-way valve core is arranged in the valve seat (41) via a valve core spring; and A damping hole is arranged on the valve seat (41) and connects the middle cavity (32) and the lower cavity (33).

6. The drill bit torque change self-adjusting device according to claim 5, It is characterized in that The one-way valve core is arranged along the central axis of the valve seat (41).

7. The drill bit torque change self-adjusting device according to claim 2, It is characterized in that A spring pressure cover (51) is arranged below the lower piston (5), the spring pressure cover (51) is fixedly connected to the cylinder body (1), and an energy storage spring (52) is coaxially arranged between the spring pressure cover (51) and the lower piston (5), with the axial ends of the energy storage spring (52) contacting the lower piston (5) and the spring pressure cover (51) respectively.

8. The drill bit torque change self-adjusting device according to claim 7, It is characterized in that The energy storage spring (52) comprises a plurality of disc springs which are arranged in sequence in the axial direction.

9. The drill bit torque change self-adjusting device according to claim 8, It is characterized in that A spring core shaft (53) is coaxially fixedly arranged at the lower part of the lower piston (5), the lower part of the spring core shaft (53) is movably arranged in the spring pressure cover (51), and the energy storage spring (52) is sleeved on the spring core shaft (53).

10. The drill bit torque change self-adjusting device according to claim 1 or 2, It is characterized in that A sealing plug (61) is fixedly arranged on the inner side of the upper portion of the cylinder body (1), and the piston rod (21) is sealingly slidably connected to the sealing plug (61).

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